CN1164122A - Plasma processor and its treating method - Google Patents

Abstract

The invention relates to a plasma treatment device and a plasma treatment method for performing fine pattern precision machining on a large-diameter sample, and improving the selectivity ratio during micromachining. In a plasma processing device with a vacuum processing chamber, a sample stage, and a plasma generating device, there is also a high-frequency power supply of 50 to 200 MH _Z VHF power between a pair of electrodes, and a static electricity of 10 gauss or more and 110 gauss or less A magnetic field forming device for a magnetic field or a low frequency magnetic field. In order to make the largest portion of the magnetic field along the direction of the lower electrode be located on the upper electrode surface or be biased toward the upper electrode side, the above-mentioned magnetic field forming device is properly set to form an electron cyclotron resonance region between the above-mentioned pair of electrodes.

Description

Plasma processor and its processing method

The present invention relates to a plasma processing machine and a processing method, in particular to a plasma processing machine and a processing method suitable for forming fine patterns in a semiconductor manufacturing process.

With the improvement of the integration level of semiconductor devices, it is required to further improve the efficiency and processing speed of microfabrication. For this reason, it is necessary to reduce the pressure of plasma processing and increase the plasma density.

There are many ways to reduce the pressure and increase the plasma density, such as: (1) using the cyclotron resonance phenomenon (ECR) of microwave (2.45GHz) electromagnetic field and static magnetic field (875 Gauss); (2) using RF (radio frequency) A power supply is used to excite the coil to generate an induced electromagnetic field and generate plasma (ICP for short).

However, when using fluorocarbon (fluorocarbon)-based gases to etch oxide films, the ECR method of (1) and the ICP method of (2) are currently used, and the gas dissociation is excessive, and it is difficult to improve the Si or SiN of the bottom layer. selection ratio.

On the other hand, in the conventional method of generating plasma by applying a radio frequency voltage between parallel plates, it is difficult to discharge stably at a pressure below 10 Pa.

There are two ways to solve the above difficulties:

(3) The dual-frequency excitation method shown in JP-A-7-297175 and JP-A-3-204925, that is, a high-frequency voltage above tens of MHz is used to generate plasma, and a low frequency below several MHz is used to carry out the sample bias control;

(4) The magnetron RIE (abbreviated as M-RIE) method shown in JP-A-2-312231, that is, a magnetic field B is applied in a direction intersecting with the self-bias electric field (E) induced on the surface of the sample , using electron suppression by the electron Lorentz force.

In addition, the method described in JP-A-56-13480 is to increase plasma density under low pressure. This is a flexible use of electron cyclotron resonance (ECR) formed by microwave (2.45GHz) of electromagnetic waves and static magnetic field (875 Gauss), and can obtain high plasma density even at a low pressure of 0.1-1Pa.

On the other hand, in the technical aspect of semiconductor etching treatment and film formation treatment using plasma, such a processing device is used, which is used for placing a sample to be processed (for example, a semiconductor wafer substrate, hereinafter referred to as a sample). A high-frequency power supply for accelerating ions in the plasma and an electrostatic adsorption film for fixing the sample on the sample stage by electrostatic attraction are prepared.

For example, the device described in the USP5,320,982 specification uses microwaves to generate plasma, uses electrostatic adsorption to fix the sample on the sample stage, and controls the sample to be controlled by a heat-conducting gas between the sample and the sample stage. On the other hand, the high-frequency power supply with sine wave output is used as a bias power supply, and the power supply is connected to the sample stage to control the ion energy injected into the sample.

In addition, as described in JP-A-62-280378, a pulsed ion control bias waveform is generated to keep the electric field strength between the plasma electrodes constant, and the bias voltage is applied to the sample stage, thus That is to say, the distribution width of the ion energy injected into the sample can be narrowed, and the dimensional accuracy of the etching process and the etching speed ratio between the treated film and the underlying material can be increased several times.

Furthermore, as described in JP-A-6-61182, electron cyclotron resonance is used to generate plasma, and a pulse bias voltage with a pulse duty factor of 0.1% or more is applied to the sample to prevent the occurrence of "grooves". "(notch).

Among the conventional technologies described above, the plasma generating methods described in JP-A-7-288195 and JP-A-7-297175 generate plasma using high frequencies of 13.56 MHz and tens of MHz. With a gas pressure of tens of −5 Pa (Pascal), good plasma suitable for oxide film etching can be generated. However, with the miniaturization of the pattern size (less than 0.2 μm), it is more urgent to make the lines of the processed pattern vertical. Therefore, the air pressure must be reduced.

However, it is difficult to generate plasma with a required density of 5×10 ¹⁰ cm ^-3 or higher at 4 Pa or lower (0.4-4 Pa) using the above-mentioned dual-frequency excitation method and M-RIE method. For example, using the above-mentioned dual-frequency excitation method, even if the plasma excitation frequency is increased, the plasma density cannot be increased above 50MHz, but it will decrease. It is difficult to achieve a plasma density of 5×10 ¹⁰ cm at a low pressure of 0.4-4Pa ^-3 or more.

Furthermore, when using the M-RIE method, the electronic Lorentz force generated on the surface of the sample causes electron suppression, and the plasma density generated by this effect should be uniform throughout the sample. However, its disadvantage is that the drift of E×B generally causes the plasma density to shift in the plane. The shift of plasma density formed directly on the surface of the sample under the suppression of electrons occurs near the sheath near the sample with high electric field intensity, so it cannot be corrected by methods such as diffusion.

The solution is as described in JP-A-7-288195, by placing a magnet in the direction of electron drift caused by E×B to weaken the magnetic field strength, so that the maximum value of the magnetic field parallel to the sample, even with the addition of 200 Gauss, a uniform plasma without offset can also be obtained. However, its disadvantage is that once the electric field intensity distribution is fixed, the conditions for forming uniform plasma are limited to a specific narrow range, so it is not easy to make necessary adjustments according to changes in processing conditions. Especially for large samples with Ф300mm or more, the distance between the electrodes is very narrow. When it is less than 20mm, the pressure on the center of the sample is more than 10% greater than the pressure on the end of the sample. In order to avoid the pressure difference on the sample, It is even more difficult to set the distance between the sample stage and the opposite electrode at 30 mm or more.

In this way, using the above-mentioned dual-frequency excitation method and M-RIE method, it is difficult to achieve a uniform plasma density of 5×10 ¹⁰ cm ^-3 in the sample plane of Ф300 mm at a low pressure of 0.4-4 Pa. Therefore, using the dual-frequency excitation method and the M-RIE method, it is difficult to uniformly and efficiently process large wafers larger than Ф300mm with a process with a line width below 0.2μm, and it is difficult to increase the selectivity ratio to the bottom layer (Si or SiN).

On the other hand, in order to significantly increase the plasma density under low pressure, the method described in Japanese Patent Application Laid-Open No. Sho 56-13480, which is the above-mentioned prior art, can be used. However, its disadvantages are: excessive (fast) gas dissociation, when using gas containing fluorine and carbon to etch silicon oxide and silicon nitride films, etc., a large number of fluorine atoms/molecules and fluorine ions are produced, which cannot reach the desired level of the bottom layer. (Si, etc.) selection ratio. The ICP method using the induced electromagnetic field of radio frequency power also has the disadvantage of too fast dissociation like the above-mentioned ECR method.

Furthermore, the generally adopted structure is that the processing gas is discharged from the periphery of the sample. At this time, the density of the central part of the sample is high, and the density of the peripheral part is low. The disadvantage is that the processing uniformity on the entire sample surface is affected. To overcome this shortcoming, an annular dike (gathering ring) is set up around the sample to stop the airflow. But the disadvantage is that the reaction product is attached to the embankment, which forms the source of impurities and reduces the qualified rate of the product.

On the other hand, in order to control the ion energy injected into the sample, a sine wave RF bias is applied to the electrode where the sample is placed. Its frequency ranges from hundreds of KHz to 13.56MHz. When using this frequency band, since the ions change with the electric field in the outer membrane (sheath), the energy of the injected ions is double-peaked, that is, there are two peaks on the low-energy side and the high-energy side. Its disadvantages are: the ion processing speed on the high-energy side is fast, causing damage to the sample; the ion processing speed on the low-energy side is slow. To eliminate damage, reduce speed; to increase processing speed, damage is caused. On the other hand, if the RF bias frequency is increased to more than 50MHz, the injected energy distribution is neat and close to a single peak, most of the energy is used to generate plasma, and the voltage applied on the sheath is large. The amplitude drops, so it is difficult to control the energy of the injected ions alone.

In the above-mentioned prior art, in the pulse bias power supply method described in JP-A-62-280378 and JP-6-61182, if an electrostatic adsorption medium layer is used between the sample stage electrode and the sample, Adding a pulse bias voltage to the sample has not been fully explored and researched. If it is used in the electrostatic adsorption method intact, as the ion current flows in, the voltage between the two ends of the electrostatic adsorption film will increase, resulting in plasma and test. The ion acceleration voltage applied between the sample surfaces decreases, and the ion energy distribution expands. Therefore, its disadvantage is that it cannot adapt to the required fine pattern processing by fully controlling the sample temperature.

In addition, when using the original sine wave output bias power supply method described in USP5,320,982, if the frequency is increased, the impedance of the outer membrane (sheath) is close to or lower than the impedance of the plasma itself. Therefore, its disadvantages are : Under the action of the bias power supply, unnecessary plasma is generated near the outer layer near the sample, which cannot be effectively used to accelerate ions, and the plasma distribution is also deteriorated, and the ion energy cannot be controlled by the bias power supply.

Furthermore, in plasma processing, proper control of the amount of ions, the amount of radicals, and the type of radicals is important to improve performance. However, in the past, gas which is a source of ions and radicals is fed into a processing chamber, plasma is generated in the processing chamber, and ions and radicals are simultaneously generated. Therefore, with the miniaturization of the processed sample, the limitation of the above-mentioned control becomes more and more obvious.

The purpose of the present invention is to provide such a plasma processing device and processing method, that is, no excessive gas dissociation phenomenon occurs, and uniform plasma can be obtained in the range of large wafers above Ф300mm, so that it is easy to process the fine patterns of large wafer samples. Precision Machining.

Another object of the present invention is to provide a plasma processor and a processing method that can uniformly and efficiently process an oxide film over an entire large wafer.

Another object of the present invention is to provide a plasma treatment machine and a treatment method for improving the selectivity of plasma treatment of insulating films (such as SiO ₂ , SiN, BPSG, etc.) in samples.

Another object of the present invention is to provide a plasma processor and method with narrow ion energy distribution, stability, low damage, easy control, and improved plasma treatment selectivity.

Another object of the present invention is to provide a plasma processor and a method for improving temperature controllability through electrostatic adsorption of a sample and processing required fine patterns precisely and stably.

Another object of the present invention is to provide a plasma processor and method capable of independently controlling ions and radicals.

The present invention is characterized in that it has the following contents:

The plasma processing machine has a vacuum processing chamber, a plasma generating device including a pair of electrodes, a sample stage with a placement surface (for placing a sample to be processed in the vacuum processing chamber), and a pressure reducer for decompressing the above-mentioned vacuum processing chamber. pressure device. In the plasma processor, there is also a high-frequency power supply and a magnetic field forming device.

A high-frequency power supply for adding high-frequency power in the VHF frequency band of 30MHz to 300MHz between the above-mentioned pair of electrodes;

a magnetic field forming device for forming a static magnetic field or a low-frequency magnetic field in a direction intersecting with the electric field generated by the high-frequency power supply between or near the pair of electrodes,

Thus, an electron cyclotron resonance region generated by the interaction of the above-mentioned magnetic field and the above-mentioned electric field is formed between the above-mentioned pair of electrodes.

The present invention is also characterized by the following content:

The plasma processing machine has a vacuum processing chamber, a plasma generating device comprising a pair of electrodes, which is also used as one of the above-mentioned electrodes, and is also used to place a sample table for processing samples in the vacuum chamber; and evacuate the above-mentioned vacuum processing chamber decompression device. In the plasma processor, there is also a high-frequency power supply and a magnetic field forming device.

A high-frequency power supply for applying a power supply in the VHF band of 50MHz to 200MHz between the above-mentioned pair of electrodes; and

A magnetic field forming device for forming a static magnetic field or a low-frequency magnetic field of 17 Gauss or more and 72 Gauss or less in a direction intersecting with the electric field generated by the above-mentioned high-frequency power supply between the above-mentioned pair of electrodes or in the vicinity thereof,

The largest part of the magnetic field along the direction of the sample table surface is set on the opposite side of the sample table so that it is away from the center of the two electrodes, and the interaction between the above-mentioned magnetic field and the electric field is used to create a gap between the pair of electrodes. An electron cyclotron resonance region is formed.

Another feature of the present invention is that it has the following contents:

The plasma processing machine has a vacuum processing chamber, a plasma generating device including a pair of electrodes, a sample stage that is also used as one of the electrodes, and is used to place samples processed in the vacuum chamber, and a decompression device that decompresses the above-mentioned vacuum chamber. device.

Using the above-mentioned plasma treatment device, the method for performing plasma treatment on its sample includes the following steps:

Using a decompression device to decompress the above-mentioned vacuum processing chamber;

A portion where a static magnetic field or a low-frequency magnetic field of 10 gauss to 110 gauss is formed in the direction intersecting the electric field between the above-mentioned pair of electrodes by a magnetic field forming device;

Using a high-frequency power supply to add a 30MHz to 300MHz VHF frequency band power supply between the above-mentioned pair of electrodes, using the interaction of the above-mentioned magnetic field and the electric field generated by the high-frequency power supply to form an electron cyclotron resonance region between the two electrodes;

The above-mentioned sample was treated with plasma generated by the above-mentioned electron cyclotron resonance.

If the present invention is adopted, in order not to cause excessive gas dissociation and to obtain a uniform plasma in which the saturated ion current distribution is less than ±5% for large wafers larger than Ф300mm, the high-frequency power supply used for plasma generation adopts 30MHz to 300MHz, the most Preferably a VHF power supply from 50MHz to 200MHz. On the other hand, a static magnetic field or a low-frequency magnetic field is formed in a direction intersecting the electric field generated between the pair of electrodes by the high-frequency power supply. In this way, between a pair of electrodes, along the sample placement surface of the sample stage, away from the center of the two electrodes on the opposite side of the sample stage, an electron cyclotron resonance region is formed by the interaction of the magnetic field and the electric field. The sample is treated with plasma generated by electron cyclotron resonance.

The magnetic field has more than 10 gauss and less than 110 gauss, preferably a static magnetic field or a low frequency (below 1KHz) magnetic field part of more than 17 gauss and less than 72 gauss, and the air pressure is set as a low pressure of 0.4Pa to 4Pa. And, the distance between the two electrodes is set to be 30 to 100 mm, preferably 30 to 60 mm. In addition, it goes without saying that the area of a pair of electrodes should be larger than the area of the sample to be processed, respectively.

The frequency f of the high-frequency power supply adopts VHF with 50MHz≤f≤200MHz, so that the plasma density is 1-2 orders of magnitude lower than that of microwave ECR. Furthermore, gas dissociation is also reduced, and the generation of unnecessary oxygen atoms/molecules and ions is also reduced by about one order of magnitude. Due to the use of VHF frequency and cyclotron resonance, appropriate high-density plasma can be obtained, with an absolute density value of 5×10 ¹⁰ cm ^-3 , and high-speed processing can be performed at a low pressure of 0.4-4Pa. Since the gas dissociation is not excessive, it does not significantly deteriorate the selectivity with an underlayer such as Si or SiN.

Compared with conventional 13.56MHz parallel plate electrodes, gas dissociation is less. In this way, the slight increase of fluorine atoms/molecules and ions can be alleviated by taking the following measures, that is, setting silicon and carbon-containing substances on the electrode surface and the wall surface of the processing chamber, and further applying a bias voltage on it, using hydrogen-containing gas to combine the hydrogen with the fluorine, which is then emitted.

Furthermore, if the present invention is adopted, then the maximum part of the magnetic field component parallel to the sample stage can be set on the opposite side of the sample stage from the center of the two electrodes, and on the sample placement surface of the sample stage. The strength of the magnetic field parallel to the sample is set below 30 Gauss, preferably below 15 Gauss, so that the Lorentz force (E×B) acting on electrons near the sample placement surface is set to be small The value of , can prevent the uneven plasma density caused by the ion drift effect caused by the Lorentz force on the sample mounting surface.

If another feature of the present invention is adopted, the electron cyclotron resonance effect can be amplified, so that the effect of the surrounding portion of the sample and its outer side is greater than that of the center, so that the surrounding portion of the sample and the vicinity of its outer side are larger than the central portion of the sample. Generate more plasma nearby. The method to reduce the electron cyclotron resonance effect is: to expand the distance between the cyclotron resonance region and the sample; to cancel the cyclotron resonance region; to reduce the degree of orthogonality between the magnetic field and the electric field.

In addition, if the gradient of the magnetic field near the cyclotron resonance magnetic field Bc is increased to narrow the ECR resonance region, the cyclotron resonance effect can be reduced. The ECR resonance region is Bc(1-a)≤B≤Bc(1+a), but the range of the magnetic field strength B becomes 0.05≤a≤0.1.

Due to the strong dissociation force in the ECR resonance region, ion generation is particularly strong. On the other hand, outside the ECR resonance region, the dissociation force is weaker than that of the ECR resonance region, and the formation of atomic groups is vigorous. By adjusting the width of the ECR resonance area and the high-frequency power applied to the upper electrode, the generation of ions and atomic groups can be controlled more independently, making it more suitable for sample processing requirements.

Another feature of the present invention is following structure:

The plasma processing machine has a vacuum processing chamber; a sample stage for placing a sample to be processed in the vacuum processing chamber; and a plasma generating device including a high-frequency power supply. In the plasma treatment device, there is also:

An electrostatic adsorption device, which uses electrostatic adsorption to fix the sample on the sample stage; and

A pulse bias voltage device is used to apply pulse bias voltage to the sample;

As a high-frequency power supply, a high-frequency voltage of 10MHz-500MHz is added, and the pressure of the vacuum processing chamber is reduced to 0.5-4.0Pa at the same time.

Another feature of the present invention is that it has a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating device. In this plasma processor there is also:

The electrostatic adsorption device is used to fix the sample on the sample stage by relying on the electrostatic adsorption force;

A pulse biasing device, which is connected to the sample stage, is used to apply a pulse bias voltage on the sample stage; and

The voltage control device is used for suppressing the change of the voltage and preventing it from correspondingly changing according to the electrostatic adsorption capacity of the electrostatic adsorption device as the pulse bias voltage is applied.

Another feature of the present invention is to provide such a plasma treatment method, which includes the following treatment program steps:

Place the sample on one of a pair of electrodes facing each other in the vacuum processing chamber;

Use electrostatic adsorption to fix the sample on the electrode;

Send the corrosive gas into the processing chamber where the sample has been placed;

Vacuum the processing chamber to reduce the air pressure to 0.5-4.0Pa;

Add 10MHz-500MHz high-frequency voltage to make the corrosive gas into plasma under the above pressure;

using plasma to etch the sample; and

A pulse bias is applied to one of the above electrodes.

Another feature of the present invention is to carry out plasma treatment to the insulating film (such as SiO ₂ , SiN, BPSG, etc.) in the above-mentioned sample according to the following program steps, these steps are:

Place the sample on one of the two electrodes facing each other;

Use electrostatic adsorption to fix the placed sample on the above electrode;

Sending the corrosive gas into the ambient gas in the processing chamber where the sample has been placed;

Turn the fed corrosive gas into plasma;

Etching the above sample with the plasma;

During etching, the above-mentioned pulse bias voltage is applied to the above-mentioned one electrode, and the bias voltage has a pulse width of 250V-800V and a duty ratio of 0.05-0.4.

If another feature of the present invention is adopted, a pulse bias power supply with specified characteristics can be added to the sample stage. The sample stage has an electrostatic adsorption device, and the electrostatic adsorption device has an electrostatic adsorption medium layer, so that the sample can be fully controlled. temperature, and stably process the required fine graphics. That is to say, the processor has an electrostatic adsorption device for fixing the sample on the sample stage by electrostatic adsorption force and a pulse biasing device for connecting the sample stage and applying a pulse bias voltage to the sample stage, and the period is The 0.2-2μs forward pulse part has a pulse bias voltage with a duty ratio of 1/2, which is applied to the sample through a capacitive element.

If another feature of the present invention is adopted, the voltage suppressing device is used to suppress the voltage change, that is, to prevent the voltage from changing correspondingly with the electrostatic adsorption capacity of the electrostatic adsorption device as the pulse bias is applied, and its composition method is: The electrostatic adsorption in one cycle of the pulse makes the voltage change on both ends of the dielectric layer less than half of the pulse bias strength. Specifically, such a method may also be adopted, that is, reducing the thickness of the dielectric chuck film on the surface of the lower electrode, and using a material with a large dielectric constant as the medium. Alternatively, the period of the pulse bias voltage is shortened to suppress the voltage rise at both ends of the dielectric layer.

If adopt another feature of the present invention, then further add the pulse width of 250V-1000V and the pulse bias of 0.05-0.4 duty ratio on an electrode when sample corrosion, can improve like this to the insulating film in the sample ( For example, the selectivity of plasma treatment of SiO ₂ , SiN, BPSG, etc.).

Another feature of the present invention is to have the following structure:

The plasma processing machine has a vacuum processing chamber, a sample table for placing a sample to be processed in the vacuum processing chamber, and a plasma generating device.

In the plasma processing plant, there are also:

Electrostatic adsorption device, which fixes the sample on the sample stage by means of electrostatic adsorption force;

A biasing device is used to apply a bias voltage to the sample;

A radical supply device, which has a device for decomposing the gas used for generating radicals in advance, and is used to supply the required number of radicals;

a gas supply device for supplying ion generating gas to the vacuum processing chamber; and

A plasma generating device for generating plasma in a vacuum processing chamber,

_SiO2 was used as a sample.

Another feature of the present invention is that, in a plasma processing apparatus having a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating apparatus including a high-frequency power supply, further comprising :

An electrostatic adsorption device is used to fix the sample on the sample stage by means of electrostatic adsorption force;

A pulse bias voltage device is used to apply pulse bias voltage to the sample;

A plasma supply device for generating radicals, which is used to change the gas for generating radicals into plasma in advance in the above-mentioned vacuum processing chamber, and supply a required amount of radicals; and

The above-mentioned plasma generating device is used for supplying ion generating gas to generate plasma,

Apply a high-frequency voltage of 10MHz-500MHz to the above-mentioned high-frequency power supply, and reduce the pressure of the vacuum processing chamber to 0.5-4.0Pa at the same time.

If another feature of the present invention is adopted, then the quantity and quality of ions and atomic groups can be controlled independently, and a pulse-shaped pulse power supply with prescribed characteristics is added on the sample stage with an electrostatic adsorption device (wherein there is an electrostatic adsorption medium layer), Therefore, the temperature of the sample can be fully controlled, and the required fine graphics can be stably processed.

It can further independently control the quantity and quality of ions and atomic groups, obtain narrow ion energy distribution, and can stably and accurately improve the selectivity of plasma treatment, etc.

Furthermore, the voltage control device can independently control the quantity and quality of ions and atomic groups, and can suppress the voltage from changing correspondingly with the electrostatic adsorption capacity of the electrostatic adsorption device as the pulse voltage is applied. The electrostatic adsorption in the cycle makes the voltage change on both ends of the dielectric layer less than half of the pulse bias voltage. Specifically, the thickness of the electrostatic adsorption film of the medium on the surface of the lower electrode can be reduced, and the medium is made of a material with a large dielectric constant. Or shorten the pulse bias cycle to suppress the voltage rise at both ends of the dielectric layer.

If another feature of the present invention is adopted, the quantity and quality of ions and atomic groups can be independently controlled. When the sample is corroded, a pulse with a pulse width of 250V-1000V and a duty cycle of 0.05-0.4 is added to an electrode The bias voltage is used to improve the selectivity of the plasma treatment of the insulating film (such as SiO ₂ , SiN, BPSG, etc.) and the bottom layer in the sample.

If another feature of the present invention is adopted, then the quantity and quality of ions and atomic groups can be independently controlled, and the high-frequency power supply used for plasma generation adopts a high-frequency voltage of 10MHz-500MHz, and the air pressure in the processing chamber is set at 0.5-4.0Pa . In this way a stable plasma can be obtained. Moreover, the use of this high-frequency voltage can improve the ionization of gas plasma, which is convenient for controlling the selectivity ratio during sample processing.

[figure 1]

It is a longitudinal sectional view of a two-electrode type plasma etching apparatus as an embodiment of the present invention.

[ Fig. 2] Fig. 2 shows an example of changes in plasma density when the frequency of a high-frequency power source for generating plasma is changed in a state where a magnetic field capable of generating cyclotron resonance is applied.

[image 3]

It shows the state of the energy gain K obtained by electrons from the high-frequency electric field at the time of cyclotron resonance and no resonance.

[Figure 4]

Indicates that the upper electrode of the magnetron discharge electrode is grounded, the magnetic field strength when the magnetic field B is applied to the lower electrode and high-frequency power is applied, the ion acceleration voltage VDC induced on the sample, and the induced voltage in the sample The relationship between the error ΔV.

[Figure 5]

It is an explanatory diagram of the magnetic field characteristics of the plasma etching apparatus in FIG. 1 .

[Figure 6]

It is an explanatory diagram of the ECR region of the plasma etching apparatus in FIG. 1 .

[Figure 7]

It is an example of an ideal output waveform used in the pulse bias power supply of the present invention.

[Figure 8]

It is the probability distribution diagram of the potential waveform and ion energy on the surface of the sample when the pulse duty ratio (T ₁ /T ₀ ) is constant and T ₀ is changed.

[Figure 9]

It is the probability distribution diagram of the potential waveform and ion energy on the surface of the sample when the pulse duty ratio is constant and T ₀ is changed.

[Figure 10]

It is a relationship graph of the maximum voltage V _cm in one cycle of the voltage generated between the two ends of the electrostatic adsorption film during the pulse off (T ₀ -T ₁ ).

[Figure 11]

is the relationship between pulse duty cycle and (V _DC /V _p ).

[Figure 12]

It shows the dependence of the etching rate ESi of silicon and oxide film and the ion energy of _ESiO2 when ionized with chlorine gas or the like.

[Figure 13]

The relationship between the etching rate ESiO ₂ and ESi of the oxide film and silicon, and the ion energy distribution is shown when CF ₄ gas is plasmaized as an example of etching an oxide film.

[Figure 14]

It is a longitudinal sectional view of a two-electrode plasma etching apparatus as another embodiment of the present invention.

[Figure 15]

It is a longitudinal sectional view of a two-electrode plasma etching apparatus as another embodiment of the present invention.

[Figure 16]

It is an explanatory diagram of the magnetic field distribution characteristic of the plasma etching apparatus of FIG. 15 .

[Figure 17]

It is an explanatory diagram of the ECR region of the plasma etching apparatus of FIG. 15 .

[Figure 18]

It is a longitudinal sectional view of a plasma etching apparatus as another embodiment of the present invention.

[Figure 19]

It is an explanatory diagram of the magnetic field distribution characteristic of the plasma etching apparatus of FIG. 18 .

[Figure 20]

It is a longitudinal sectional view of a two-electrode plasma etching apparatus as another embodiment of the present invention.

[Figure 21]

It is a vertical cross-sectional view of a two-electrode plasma etching apparatus according to another embodiment of the present invention.

[Figure 22]

It is an explanatory diagram of the magnetic field distribution characteristic of the plasma etching apparatus of FIG. 21 .

[Figure 23]

It is a cross-sectional view of an important part of a two-electrode type plasma etching apparatus as another embodiment of the present invention.

[Figure 24]

is a longitudinal sectional view of the plasma etching apparatus in FIG. 23 .

[Figure 25]

It is a diagram of another embodiment of the magnetic field forming device.

[Figure 26]

It is a longitudinal sectional view of a two-electrode plasma etching apparatus as another embodiment of the present invention.

[Figure 27]

It is a longitudinal sectional view of a two-electrode type plasma etching apparatus as another embodiment of the present invention.

[Figure 28]

It is a longitudinal sectional view of a two-electrode plasma etching apparatus as another embodiment of the present invention.

[Figure 29]

It is an explanatory diagram of the magnetic field distribution characteristic of the plasma etching apparatus of FIG. 28 .

[Figure 30]

It is a longitudinal sectional view of a two-electrode plasma etching apparatus as another embodiment of the present invention.

[Figure 31]

It is a vertical cross-sectional view of another embodiment of the improved two-electrode type plasma etching apparatus shown in FIG. 1 .

[Figure 32]

Fig. 32 is a relationship diagram between the frequency of plasma power generation and the minimum air pressure for stable discharge.

[Figure 33]

is a graph showing the relationship between the frequency of the pulsed bias power supply and the accumulated power.

[Figure 34]

It is a longitudinal sectional view of an example in which the present invention is applied to an inductively coupled discharge method non-magnetic field type plasma etching apparatus among external energy supply discharge methods.

[Figure 35]

It is a longitudinal sectional view of a plasma etching apparatus as another embodiment of the present invention.

[Figure 36]

It is a front view of a partial longitudinal section when the present invention is used in a microwave plasma processing device.

[Figure 37]

It is a longitudinal sectional view of a plasma etching apparatus as another embodiment of the present invention.

[Figure 38]

It is a front view of a longitudinal section of a part of a plasma processing apparatus as another embodiment of the present invention.

[Figure 39]

It is a vertical cross-sectional view of a two-electrode type plasma etching apparatus capable of independently controlling ions and atomic groups as another embodiment of the present invention.

[Figure 40]

It is a partial detailed view of a two-electrode type plasma etching apparatus capable of independently controlling ions and atomic groups as another embodiment of the present invention.

According to the present invention, it is possible to provide a plasma processing device and a plasma processing method which can easily process fine and precise patterns on a large diameter sample of φ300 mm or more, and which can also improve the selectivity during micro processing. It is also possible to provide a plasma processing apparatus capable of performing uniform and high-speed processing, especially oxide film processing, on the entire surface of a large-diameter sample, and a processing method thereof.

According to the present invention, it is also possible to provide a plasma processing apparatus and a plasma processing method capable of improving the selectivity of plasma processing of an insulating film (for example, SiO ₂ , SiN, BPSG, etc.) in a sample.

In addition, it is possible to provide a plasma processing apparatus and a plasma processing method having good controllability, narrow energy distribution, and high plasma processing selectivity.

It is also possible to provide a plasma processing apparatus and a plasma processing method having good controllability, narrow ion energy distribution, and high plasma processing selectivity when using a sample stage having a dielectric layer for electrostatic adsorption.

Furthermore, it is also possible to provide a plasma processing device and a plasma processing device that can reduce the pressure in the processing chamber of the plasma processing device by independently controlling the quality and quantity of ions and atomic groups, easily perform fine processing of fine patterns, and improve the selectivity ratio during fine processing. Plasma treatment method.

Furthermore, it is also possible to provide a plasma processing device and a plasma processing device capable of improving the selectivity of plasma processing of an insulating film (such as SiO ₂ , SiN, BPSG, etc.) in a sample by independently controlling the quality and quantity of ions and atomic groups. method.

Examples of the present invention are described below. First, FIG. 1 shows a first embodiment, that is, the present invention is applied to a counter electrode type plasma etching machine.

In FIG. 1 , a processing chamber 10 serving as a vacuum container has a pair of opposing electrodes composed of an upper electrode 12 and a lower electrode 15 . A sample 40 is placed on the lower electrode 15 . In order to make the pressure difference on the surface of the sample not exceed 10% when processing a large sample of Ф300 mm or more, the gap between the two electrodes 12 and 15 is preferably set at more than 30 mm. And, in order to reduce fluorine atoms, molecules and ions, the gap is preferably set to be less than 100mm, preferably less than 60mm, from the consideration of effectively utilizing the reaction on the surface of the upper and lower electrodes. A high-frequency power source 16 is connected to the upper electrode 12 to supply high-frequency energy through a matching box 162 . 161 is a high-frequency power modulation signal source. A filter 165 is connected between the upper electrode 12 and the ground, and the filter 165 has low impedance to the frequency components of the bias power supply 17 and high impedance to the frequency components of the high-frequency power supply 16 .

The surface area of the upper electrode 12 is larger than the area of the sample 40 to be processed, and the voltage can be efficiently applied to the outer membrane on the sample surface by applying the bias power supply 17 .

On the lower side surface of the upper electrode 12 is provided an upper electrode cover 30 as a fluorine removal plate, which is composed of silicon, carbon or SiC. In addition, a gas introduction chamber 34 is provided on the upper part of the upper electrode 12, which includes a gas diffusion plate 32 for diffusing the gas in a predetermined distribution state. The gas required for processing such as sample corrosion is sent from the gas supply unit 36 into the processing chamber 10 through the gas diffusion plate 32 of the gas introduction chamber 34 , the upper electrode 12 and the holes 38 on the upper electrode cover 30 . The vacuum pump 18 connected to the outer chamber 11 through the valve 14 evacuates the outer chamber 11 to adjust the air pressure of the processing chamber 10 to the pressure required for sample processing. In order to increase the plasma density and make the reaction in the processing chamber uniform, a circular ring 37 for suppressing discharge is provided around the processing chamber 10 . A gap for exhaust is provided in the ring 37 for suppressing discharge.

A magnetic field forming device 200 is provided above the upper electrode 12 for forming a magnetic field parallel to the surface of the sample 40 and perpendicular to the electric field E formed between the electrodes. The magnetic field forming device 200 has a magnetic core 201 , an electromagnetic coil 202 and an insulator 203 . The structural material of the upper electrode 12 is a non-magnetic conductor such as aluminum and aluminum alloy. The structural material of the processing chamber 10 is a non-magnetic material, such as aluminum and aluminum alloys, alumina, quartz, SiC, and the like. The magnetic core 201 adopts an axially rotationally symmetrical structure, and its section is generally E-shaped, and is divided into magnetic core parts 201A and 201B. The magnetic field B formed is that the magnetic flux shoots from the central upper part of the processing chamber 10 to the upper electrode 12, and flows along the upper electrode 12. extending substantially parallel to the outer circle. The magnetic field generated between the two electrodes by the magnetic field forming device 200 has a static magnetic field of 10 Gauss to 110 Gauss, preferably a static magnetic field of 17 Gauss to 72 Gauss, or a low frequency magnetic field (below 1KHz) that produces cyclotron resonance.

It is well known that the magnetic field strength Bc (Gauss) at which cyclotron resonance occurs has a relationship of Bc=0.357×f (MHz) to the plasma generation high-frequency frequency f (MHz).

The two electrodes 12 and 15 in the present invention are a pair of electrodes facing each other. In essence, it is sufficient that the two electrodes are parallel to each other. According to the requirements of plasma generation characteristics, the electrodes 12 and 15 can also have certain concave or convex surfaces. It is characterized in that such double electrodes can easily make the distribution of the electric field between the electrodes uniform, and by improving the uniformity of the magnetic field perpendicular to the electric field, it is relatively easy to uniformly generate plasma by means of cyclotron resonance.

The lower electrode 15 on which the sample 40 is placed and fixed has a bipolar electrostatic chuck 20 . That is to say, the lower electrode 15 is composed of the first lower electrode 15A on the outer side and the second lower electrode 15B provided on the upper part of the inner side through the insulator 21, and static electricity is provided on the upper surfaces of the first and second lower electrodes. Adsorption medium layer (hereinafter referred to as electrostatic adsorption film) 22 . Between the first and second lower electrodes, a DC power supply 23 is connected through coils 24A and 24B for filtering high-frequency components. A DC voltage is applied between the two lower electrodes so that the side of the second lower electrode 15B is positive. In this way, the Coulomb force acting between the sample 40 and the two lower electrodes through the electrostatic adsorption film 22 can adsorb and fix the sample 40 on the lower electrode 15 . For the electrostatic adsorption film 22, aluminum oxide, a medium in which aluminum oxide is mixed with titanium oxide, or the like can be used. Also, the power supply 23 uses a DC power supply of several hundred volts.

Also, a pulse bias power supply 17 for supplying a pulse bias voltage with a width of 20V-1000V is connected to the lower electrode 15 (15A, 15B) through DC blocking capacitors 19A, 19B for eliminating DC components, respectively.

Heretofore, the bipolar electrostatic chuck has been described, but other electrostatic chucks, such as unipolar and n-polar (n≧3), can also be used.

During the etching process, the sample 40 to be processed is placed on the lower electrode 15 of the processing chamber 10 and is attracted by the electrostatic chuck 20 . On the other hand, the gas required for the etching process of the sample 40 is sent into the processing chamber 10 from the gas supply unit 36 through the gas introduction chamber 34 . The outer chamber 11 is evacuated by a vacuum pump 18 to reduce the pressure of the processing chamber 10 to, for example, 0.4-4.0 Pa (Pascal). Then, 30MHz-300MHz, preferably 50MHz-200MHz high-frequency power is output from the high-frequency power supply 16 to make the processing gas in the processing chamber 10 into plasma.

Using 30-300MHz high-frequency power and the static magnetic field of 10 gauss or more and 110 gauss or less generated by the magnetic field forming device 200, an electron cyclotron resonance is generated between the upper electrode 12 and the lower electrode 15. At this time, 0.4-4.0 Pa low pressure high density plasma.

In addition, a pulse bias voltage is applied to the lower electrode 15 from the pulse bias power supply 17, the bias voltage is a voltage of 20V-1000V, the period is 0.1μs-10μs, preferably 0.2μs-5μs, and the duty ratio of the positive pulse part is 0.05 -0.4, in order to control the electrons and ions in the plasma, etch the sample 40.

The corrosive gas is injected into the processing chamber 10 through the holes 38 formed in the upper electrode 12 and the upper electrode cover 30 after being distributed in a desired manner by the gas diffusion plate 32 .

Furthermore, the upper electrode cover 30 is made of carbon or silicon, or a material containing carbon or silicon, in order to eliminate fluorine and oxygen components, and to increase the selectivity ratio of photoresist or silicon to the bottom layer.

In order to improve the microfabrication efficiency of large samples, the high frequency power source 16 for plasma generation can adopt a higher frequency to improve the stability of the discharge in the low pressure area. In order to obtain a uniform plasma for a large sample at a low pressure of 0.4Pa-4Pa with a plasma density of 5×10 ¹⁰ -5×10 ¹¹ cm ^-3 without excessive gas dissociation, A high-frequency power source 16 for plasma generation is connected to the upper electrode 12 . On the other hand, the ion energy control bias power supply 17 is connected to the lower electrode 15 on which the sample is placed, and the distance between these two electrodes is set to 30-100 mm.

The high-frequency power supply 16 for plasma generation adopts 30MHz-300MHz, preferably VHF of 50MHz-200MHz, and utilizes a static magnetic field or a low-frequency (below 1KHz) magnetic field of more than 10 Gauss and less than 110 Gauss, preferably more than 17 Gauss and less than 72 Gauss Partial interaction generates electron cyclotron resonance between the upper electrode 12 and the lower electrode 15 .

FIG. 2 shows an example of changes in plasma density when the frequency of a high-frequency power source for generating plasma is changed while a magnetic field for generating electron cyclotron resonance is applied. The supply gas is argon plus C ₄ F ₈ 2-10% gas, and the pressure of the processing chamber is 1Pa. The plasma density is 1 at the time of f=2450MHz microwave ECR, which is a standard value. The dotted line in the figure represents the result obtained when there is no magnetic field.

When 50MHz≤f≤200MHz, the plasma density is 1-2 orders of magnitude lower than that of microwave ECR. And there is less gas dissociation, and the occurrence of unwanted fluorine atoms/molecules and ions is also more than 1 order of magnitude lower. Utilizing the frequency in the VHF band and cyclotron resonance, it is possible to obtain a suitable high-density plasma with an absolute value of plasma density of 5×10 ¹⁰ cm ^-3 or more, and high-speed processing can be performed at a low pressure of 0.4-4 Pa. Moreover, since the gas dissociation is not excessive, the selectivity ratio to the underlayer such as Si and SiN is not significantly lowered for insulating films such as SiO ₂ .

At 50MHz≤f≤200MHz, compared with the past 13.56MHz parallel plate electrode, the gas dissociation is slightly more, but the fluorine atoms/molecules and ions formed thereby increase very little, which can be passed on the surface of the electrode and the wall of the container. It is improved by placing silicon and carbon-containing substances on it. Alternatively, a bias voltage is further applied to the surface of the electrode and the wall surface of the container to combine fluorine with carbon and silicon and then discharge it, or use hydrogen-containing gas to combine hydrogen with fluorine and discharge it, which can be improved.

If the frequency of the high-frequency power supply is above 200MHz, especially above 300MHz, the plasma density increases, but the gas dissociation is excessive, the fluorine atoms/molecules and ions increase too much, and the selectivity ratio of Si and SiN to the bottom layer is significantly reduced, so it is not necessary Hope to do so.

Fig. 3 shows the energy gain K obtained by electrons from a high-frequency electric field at cyclotron resonance and without resonance. When there is no magnetic field, it is assumed that the energy obtained by electrons in one cycle of high frequency is e0, and when the cyclotron resonant magnetic field Bc=2πf (m/e) is added, the energy obtained by electrons in one cycle of high frequency is e1, At this time, e1 and e0 can be calculated according to formula 1. $e_0=\frac{{\mathrm{<figure-callout\; id="2"\; label="e"\; filenames="A97103106.100581.png,A97103106.100751.png"\; state="\{\{state\}\}">e</figure-callout>}}^2{\mathrm{E.}}^2}{2m}\left(\frac{\mathrm{\&gamma;}}{{\mathrm{\&omega;}}^2+{\mathrm{\&gamma;}}^2}\right)$ ${\mathrm{<figure-callout\; id="1"\; label="e"\; filenames="A97103106.100571.png,A97103106.100581.png"\; state="\{\{state\}\}">e</figure-callout>}}_1=\frac{{\mathrm{<figure-callout\; id="2"\; label="e"\; filenames="A97103106.100581.png,A97103106.100751.png"\; state="\{\{state\}\}">e</figure-callout>}}^2{\mathrm{E.}}^2\mathrm{\&gamma;}}{4m}(\frac{1}{{\mathrm{\&gamma;}}^2+{(\mathrm{\&omega;}-\mathrm{\&omega;\; c})}^2}+\frac{1}{{\mathrm{\&gamma;}}^2+{(\mathrm{\&omega;}+\mathrm{\&omega;\; c})}^2})$ ...Formula 1

In the formula: E is the electric field strength

When K is assumed as its ratio (=e1/e0), K can be represented by the following formula. In the formula, m: the mass of the electron, e: the charge of the electron, f: the applied frequency

K＝(1/2)(γ ² +ω ² ){1/(γ ² +(ω-ωc) ² )+(1/(γ ² +(ω+ωc) ² ))}

Where: γ: collision frequency,

ω: excitation angular frequency

ωc: cyclotron angular frequency Generally speaking, the K value increases as the air pressure decreases and the frequency increases. Fig. 3 shows the situation of Ar (argon) gas, when the pressure=1Pa, f≥50MHz, K≥150, compared with no magnetic field, the dissociation can also be promoted under low pressure. The cyclotron resonance effect decreases sharply at frequencies below 20 MHz at pressure = 1 Pa. Even from the characteristics shown in Fig. 2, it can be seen that at frequencies below 30 MHz, there is little difference from the time when there is no magnetic field, and the cyclotron resonance effect is small.

Furthermore, if the gas pressure is lowered, the cyclotron resonance effect increases, but when the gas pressure is lower than 1 Pa, the electron temperature of the plasma rises, and the negative effect of excessive dissociation increases. In order to suppress excessive gas dissociation and increase the plasma density to above 5×10 ¹⁰ cm ^-3 , the gas pressure can be set at 0.4Pa-4Pa, preferably 1Pa-4Pa.

In order to exert the cyclotron resonance effect, it is necessary to set the K value above several tens. It can also be seen from Figures 2 and 3 that in order to avoid excessive gas dissociation and effectively utilize the cyclotron resonance effect, when the air pressure is 0.4Pa-4Pa, the high-frequency power supply for plasma generation must use 30-300MHz, and the most Preferably 50-200MHz VHF.

Fig. 4 shows the ion acceleration voltage induced by the sample when the upper electrode is grounded, a uniform transverse magnetic field B is applied to the lower electrode, and a high-frequency power of 68 MHz is applied at the same time in a conventional magnetron type container. The deviation ΔV between VDC and the induced voltage VDC in the sample. If the intensity of the magnetic field B is increased, the Lorentz force acting on the electrons will reduce the ion acceleration voltage VDC and increase the plasma density. However, in the conventional magnetron discharge type, since the intensity of the magnetic field B is as high as about 200 gauss, the disadvantages are that the in-plane uniformity of the plasma density is reduced, the deviation ΔV of the induced voltage is increased, and the damage of the sample is increased. .

From Fig. 4, compared with 200 Gauss in the conventional magnetron discharge type, in order to reduce ΔV to 1/5 to 1/10, the strength of the magnetic field B is set to 30 Gauss or less near the sample surface. , preferably below 15 Gauss. This is good for eliminating damage.

The cyclotron resonance region is formed in the middle of the upper electrode 12 and the lower electrode 15, and deviates slightly from the middle position of the two electrodes to the upper electrode side. FIG. 5 shows that the horizontal axis is the distance from the sample surface (lower electrode 15 ) to the upper electrode 12 and the vertical axis is the magnetic field. In the example of Fig. 5, the ECR region is formed at a position about 30 mm away from the sample surface under the conditions of applied frequency f1 = 100 MHz, Bc = 37.5 G, and electrode distance = 50 mm.

Thus, according to the present invention, between the upper electrode 12 and the lower electrode 15, the largest part of the magnetic field component parallel to the lower electrode 15 (sample placement surface) is set on the upper electrode surface, or away from both electrodes. The middle of the center is biased towards the upper electrode side. In this way, the magnetic field intensity parallel to the sample on the lower electrode surface is set to be less than 30 Gauss, preferably less than 15 Gauss, and the Lorentz force (E×B) acting on the electrons near the lower electrode surface Setting it to a small value can eliminate the in-plane inhomogeneity of the plasma density caused by the electron drift effect caused by the Lorentz force on the lower electrode surface.

If the magnetic field forming device 200 of the embodiment of Fig. 1 is adopted, as shown in Fig. 6, the ECR region is formed at substantially the same height from the lower electrode 15 (sample placement surface) except near the center of the sample. position. Therefore, for a large sample, plasma treatment can be uniformly performed. However, near the center of the sample, the ECR region is formed at a position higher than the surface on which the sample is placed. Since there is a distance of more than 30mm between the ECR area and the sample stage, ions and atomic groups diffuse in this space to form an averaged state, so there is no problem for normal plasma processing. However, in order to uniformly perform plasma treatment on the entire sample, the ECR region is preferably formed at the same height from the entire sample surface, or the ECR region on the outside of the sample is closer to the sample stage than the ECR region near the center Sideways. This measure will be described in detail later.

As mentioned above, in the embodiment of the present invention shown in FIG. 1, the high-frequency power source 16 for plasma generation uses a high-frequency power of 30 to 300 Mhz, and utilizes electron acceleration cyclotron resonance to perform gas dissociation. Stable plasma can be obtained even at a low pressure of 0.4 Pa to 4 Pa in the chamber 10 . In addition, since the collision of ions in the space charge layer is reduced, the directionality of ions can be improved when processing the sample 40, and the vertical microfabrication capability can be improved.

Around the processing chamber 10, the plasma is concentrated near the sample 40 by using the ring 37 for suppressing the discharge, so as to increase the plasma density, and at the same time reduce unnecessary deposits attached to the outer part of the ring 37 for suppressing the discharge to at the lowest limit.

Furthermore, the ring 37 for suppressing discharge is made of semiconductor and conductor materials such as carbon and silicon or SiC. If the circular ring 37 for suppressing discharge is connected to a high-frequency power source, and sputtering is generated by ions, the amount of deposition on the circular ring 37 can be reduced, and the effect of removing fluorine can also be obtained.

In addition, if carbon and silicon or a receiver cover 39 containing carbon and silicon are provided on the insulator 13 around the sample 40, fluorine can be removed when the insulating film such as SiO ₂ is subjected to plasma treatment with a fluorine-containing gas, so there is help to increase the selection ratio. In this case, if the thickness of the insulator 13 at the lower part of the receiver cover 39 is reduced to 0.5-5 mm, and a part of the power of the bias voltage 17 is applied to the receiver cover 39, the sputtering effect of ions can be utilized. to improve the above effect.

The dielectric electrostatic adsorption film 22 is sandwiched by the potential of the DC power supply 23, and an electrostatic adsorption circuit is formed through the lower electrodes 15 (15A, 15B). In this state, the sample 40 is fixed to the lower electrode 15 by the electrostatic force. A heat transfer gas such as helium, nitrogen, argon, etc. is supplied onto the back surface of the sample 40 fixed by electrostatic force. The heat transfer gas is filled into the concave portion of the lower electrode 15 . Its pressure is set at hundreds of Pascals to thousands of Pascals. The electrostatic attraction force can be considered to be almost zero between the concave portions provided with gaps, and the electrostatic attraction force is generated only at the convex portions of the lower electrode 15 . However, as described later, by properly setting the voltage in the DC power supply 23, an appropriate adsorption force can be set so that it can fully withstand the pressure of the heat transfer gas, so the heat transfer gas will not cause the sample 40 to move or fly out. .

However, the effect of the electrostatic adsorption film 22 will reduce the biasing effect of the pulse bias voltage on the ions in the plasma. Even the conventional method of biasing with a sine wave power supply has this effect. But not obvious. However, for the pulsed bias voltage, since the feature of narrow ion energy width is sacrificed, a great problem arises.

A feature of the present invention is that a voltage suppressing device is specially provided in order to suppress the voltage rise phenomenon between the two ends of the electrostatic adsorption film 22 as the pulse bias is applied and to improve the effect of the pulse bias.

As an example of the voltage suppressing means, there may be adopted a structure having the effect that the voltage change (V _cm ) in one cycle of the bias voltage generated between both ends of the electrostatic adsorption film as the pulse bias is applied is equivalent to that of the pulse bias. 1/2 or less of the pressure (V _p ). The specific method is to reduce the thickness of the electrostatic adsorption film made of medium on the surface of the lower electrode 15, or use a material with a large dielectric constant as the medium to increase the electrostatic capacity of the medium.

As another voltage suppressing device, the method may be to shorten the period of the pulse bias voltage so as to suppress the rise of the voltage Vcm. Furthermore, the electrostatic adsorption circuit and the pulse bias circuit can be separated and arranged in other positions, for example, on another opposite electrode other than the electrode where the sample is placed and fixed, or on an additional third electrode. superior.

The relationship between the voltage change and the pulse bias voltage generated between the two ends of the electrostatic adsorption film in one cycle of the pulse bias voltage formed by the voltage suppressing device of the present invention will be described in detail below using FIGS. 7 to 13 .

First, an example of a desired output waveform used in the pulse bias power supply 17 of the present invention is shown in FIG. 7 . In the figure, let the pulse width be Vp, the frequency period be T ₀ , and the forward pulse width be T ₁ .

When the waveform shown in Figure 7(A) is applied to the sample through the DC blocking capacitor and the dielectric layer for electrostatic adsorption (hereinafter referred to as the electrostatic adsorption film), the surface of the sample in a stable state where plasma is generated using another power source The potential waveform of is shown in Fig. 7(B).

In the figure, V _DC : DC component voltage of the waveform

V _f : Floating potential of the plasma

V _cm : The maximum voltage in one cycle generated between the two ends of the electrostatic adsorption film

In Figure 7(B), the part of voltage (1) that is positive than V _f is mainly the part that only _absorbs electron current; the part that is negative than V _f is the part that absorbs ion current; The part that balances with ions (V _f is usually a few V to ten-odd V).

In addition, in Fig. 7(A) and subsequent descriptions, it is assumed that the capacity of the DC blocking capacitor and the capacity of the insulator near the sample surface are much larger than the capacity of the electrostatic adsorption film (hereinafter referred to as the electrostatic adsorption capacity) .

The value of V _cm can be represented by the following formula (Expression 2).

In the formula, q: the ion current density (average value) flowing into the sample during (T ₀ -T ₁ )

C: Electrostatic adsorption capacity per unit area (average value)

i _i : ion current density

ε _r : Dielectric constant of the electrostatic adsorption film

d: Thickness of electrostatic adsorption film

ε ₀ : Dielectric constant (constant) in vacuum

K: Electrode coating (dressing) rate of electrostatic adsorption film (≤1)

Figure 8 and Figure 9 show the pulse duty ratio: (T _i /T ₀ ) is a certain value, when T ₀ is changed, the potential waveform on the sample surface and the probability distribution of ion energy. Among them, it is assumed that

T ₀₁ : T ₀₂ : T ₀₃ : T ₀₄ : T ₀₅ = 16:8:4:2:1

As shown in Figure 8(1), when the pulse period T ₀ is too large, the potential waveform on the surface of the sample deviates greatly from the rectangular wave and becomes a triangular waveform, and the ion energy shows a certain distribution from low to high as shown in Figure 9 ,Ineffective.

As shown in Fig. 8 (2) to (5), as the pulse period T ₀ decreases, (V _cm /V _p ) becomes a value smaller than 1, and the ion energy distribution becomes narrower.

In Fig. 8 and Fig. 9, T ₀ =T ₀₁ , T ₀₂ , T ₀₃ , T ₀₄ , T ₀₅ corresponds to (V _cm /V _p )=1.0, 0.63, 0.31, 0.16, 0.08.

The relationship between the off-circuit (T ₀ -T ₁ ) period of the pulse and the maximum voltage V _cm in one cycle of the voltage generated across the electrostatic adsorption film is shown in FIG. 10 .

As an electrostatic adsorption film, when titanium oxide-containing aluminum oxide (ε _r =10) with a thickness of 0.03 mm is used to coat about 50% of the surface of the electrode (K = 0.5), the ion current density i _i =5m A/cm The change of the V _cm value in the medium-density plasma of ² is shown by the thick line (the line of the standard condition) in FIG. 10 .

It can be seen from Figure 10 that as the off-circuit (T ₀ -T ₁ ) period of the pulse increases, the voltage V _cm generated between the two ends of the electrostatic adsorption film increases proportionally to it, exceeding the usual The pulse voltage V _p used.

For example, in a plasma etcher, the voltage is generally limited to the following ranges depending on damage, selectivity to the underlayer and mask, shape, etc.

When the gate is corroded 20V≤V _p ≤100V

When metal corrodes 50V≤V _p ≤200V

When the oxide film is corroded 250V≤V _p ≤1000V

If the following condition of (V _cm /V _p )≦0.5 is to be satisfied, the upper limit of (T ₀ −T ₁ ) in the standard state is as follows.

During gate corrosion (T ₀ -T ₁ )≤0.1 5μs

Metal corrosion (T ₀ -T ₁ )≤0.35μs

When corroding the oxide film, it is (T ₀ -T ₁ )≤1.2μs. However, if T ₀ is close to 0.1μs, the impedance of the outer ion layer will be close to or lower than the plasma impedance, so unwanted plasma is generated. At the same time, The bias power supply cannot be effectively used by ion acceleration, so the effect of using the bias power supply to control ion energy is reduced, so T ₀ should be higher than 0.1 μs. The most ideal is higher than 0.2μs.

Therefore, in the process of controlling _Vp at a lower level, such as gate corrosion, it is necessary to change the material of the electrostatic adsorption film to a material with a high dielectric constant of 10-100 (for example: Ta ₂ O ₃ , ε _r =25) , or make the film thickness thinner without lowering the insulation withstand voltage (for example, the film thickness of 10 μm to 400 μm is desired to be as thin as 10 μm to 100 μm).

Figure 10 also shows the V _cm values when the electrostatic capacitance C per unit area is increased to 2.5 times, 5 times, and 10 times respectively. Even if the electrostatic adsorption film is improved, from the current situation, the electrostatic capacitance C can only be increased by a few digits at most. times. If V _cm ≤ 300 volts, c ≤ 10c ₀ , then 0.1 μs ≤ (T ₀ −T ₁ ) ≤ 10 μs.

The portion (T ₀ −T ₁ ) effective for plasma processing by ion acceleration is desired to be as small as possible as the pulse duty ratio (T ₁ /T ₀ ).

Fig. 11 shows the results estimated as (V _DC /V _p ) as the efficiency of the plasma treatment with the time average added. It is desired to reduce (T ₁ /T ₀ ) and increase (V _DC /V _p ).

The efficiency of the plasma treatment is assumed to be 0.5≤(V _DC /V _p ), plus the following condition (V _cm /V _p )≤0.5, the pulse duty ratio is about (T ₁ /T ₀ )≤0.4.

In addition, the smaller the pulse duty ratio (T ₁ /T ₀ ), the more effective the control of ion energy is. However, if it is too small to exceed the necessary level, the value of the pulse width _T1 becomes small, which is about 0.05 μs. As a result, many frequency components of tens of MHz are included, and the separation of high-frequency components for generating plasma as described later is also difficult. It becomes difficult, as shown in Figure 11, (V _DC /V _p ) decreases very little between 0≤(T ₁ /T ₀ )≤0.05, and (T ₁ /T ₀ ) is higher than 0.05. A problem occurred.

Here, as an example of gate etching, FIG. 12 shows the dependence of the etching rate ESi of silicon and the underlying oxide film on the ion energy of ESiO ₂ after chlorine gas is plasmatized at 10 mT. The etching rate ESi of silicon is a certain value under the condition of low ion energy. When the ion energy is higher than 10V, ESi also increases with the increase of ion energy. On the other hand, the corrosion rate ESiO ₂ of the oxide film as the bottom layer is 0 when the ion energy is lower than 20V. If 20V is exceeded, ESiO ₂ and ion energy increase simultaneously. As a result, when the ion energy is 20 V or less, there is a region where the selectivity ratio ESi/ESiO ₂ to the bottom layer becomes ∞, and when the ion energy is 20 V or more, the selectivity ratio ESi/ESiO ₂ to the bottom layer increases with ion energy , falling rapidly.

Figure 13 shows an example of etching an oxide film (SiO ₂ , BPSG, HISO, etc.) which is a type of insulating film, showing the etching rate of the oxide film and silicon after plasmating C ₄ F ₈ gas at 1.0 Pa. ESiO ₂ and ion energy distribution of ESi .

The corrosion rate of the oxide film ESiO ₂ is negative in the case of low ion energy, resulting in deposits. When the ion energy is close to 400V, ESiO ₂ rapidly rises towards the positive direction. Then slowly increase. In addition, the etching rate ESi of the underlying silicon, compared with ESiO ₂ , gradually increases from (-) etching to (+) etching when the ion energy is high. As a result, near the position where ESiO ₂ changes from (-) to (+), the selectivity ratio ESiO ₂ /ESi to the bottom layer becomes ∞, and when the change continues, ESiO ₂ /ESi decreases rapidly with the increase of ion energy.

As shown in Fig. 12 and Fig. 13, for the applicable actual process, after considering the value of ESi and ESiO ₂ and the value of ESi/ESiO ₂ and ESiO ₂ /ESi, adjust the bias power supply to make the ion energy reach an appropriate value.

In addition, if the corrosion rate before the bottom film appears, the corrosion rate is given priority, after the bottom film is corroded, the selection ratio is given priority, and the ion energy is changed to before and after the bottom film corrosion, then a better result can be obtained. characteristics.

However, the characteristics shown in FIGS. 12 and 13 are characteristics limited to a portion where the ion energy distribution is narrow. When the energy distribution of ions is wide, each corrosion rate is its time average value, so it cannot be set to an appropriate value, and the selectivity drops significantly.

According to experiments, if (V _DC /V _p ) is 0.3 or less, then the ion energy distribution range is ±15% or less. A high selection ratio of 30 or more was obtained even for the characteristics shown in Fig. 12 and Fig. 13 . Furthermore, if (V _DC /V _p )≤0.5, the selection ratio and the like are improved compared with the conventional sine wave bias method.

In this way, as a voltage suppression device that suppresses the voltage change (V _cm ) of the pulse bias voltage generated between the two ends of the electrostatic adsorption film in one cycle, it is configured to reach 1/2 or less of the pulse bias voltage V _p at V _cm as well. Specifically, the capacitance of the dielectric can be increased by reducing the film thickness of the dielectric electrostatic adsorption film 22 provided on the surface of the lower electrode 15, changing the dielectric to a material with a high dielectric constant, or the like. Or shorten the pulse bias period to 0.1μs～10μs, and hope to shorten it to 0.2μs～5μs (repetition frequency: corresponding to 0.2MHz～5MHz), and set the pulse duty ratio (T ₁ /T ₀ ) to 0.05≤( T ₁ /T ₀ )≤0.4 to suppress the voltage change across the electrostatic adsorption film.

Also can combine factors such as the film thickness of the electrostatic adsorption film of above-mentioned dielectric and the dielectric constant of dielectric and the period of pulse bias voltage, make the change of the voltage V _cm that produces between above-mentioned electrostatic adsorption film two ends meet above-mentioned (V _cm /V _p )≤0.5 condition.

Next, an example in which the vacuum processing chamber of FIG. 1 is used for etching an insulating film (for example, SiO ₂ , SiN, BPSG, etc.) will be described.

Gas 19 adopts C ₄ F ₈ : 1-5%; Ar: 90-95%, O ₂ : 0-5%, or C ₄ F ₈ : 1-5%; Ar: 70-90%, O ₂ : 0 ~5%, CO: gas composed of 10~20%. The high-frequency power supply 16 for plasma generation adopts a higher frequency than before, for example, a frequency of 40 MHz, and seeks stable discharge in a low-pressure region of 1 to 3 Pa.

In addition, when dissociation occurs more than necessary due to the high frequency of the high frequency power supply 16 for the plasma source, the output of the high frequency power supply 16 is controlled on, off or level modulated by the high frequency power supply modulation signal source 161 . At high levels, ions are generated much (faster) than clusters. At low levels, more radicals are formed than ions. The turn-on (or high level during level modulation) time is about 5 to 50 μs, the off time (or low level during level modulation) is 10 to 100 μs, and the period is 20 μs to 150 μs. In this way, unnecessary dissociation can be prevented, and at the same time, a desired ion group ratio can be obtained.

In addition, the modulation period of the high-frequency power supply for the plasma source is generally longer than the pulse bias period. Therefore, by adjusting the modulation period of the high-frequency power supply for the plasma source to an integer multiple of the pulse bias period, the phase between the two can be optimized, and the selectivity can be improved.

In addition, the ions in the plasma are accelerated and vertically injected into the sample by applying a pulse bias voltage, so as to control the ion energy. Pulse bias voltage 17, using for example pulse period: T=0.65; pulse width: T1=0.15μs; pulse width: _Vp =800V power supply, the distribution range of ion energy can reach ±15% or less, and the Si Plasma treatment with excellent characteristics with a selectivity ratio of 20 to 50 to SiN.

Next, a two-electrode type plasma etching apparatus according to another embodiment of the present invention, which has the same structure as that shown in FIG. 1 , will be described with reference to FIG. 14 . However, the difference is that the lower electrode 15 holding the sample 40 has a monopolar electrostatic chuck 20 . The dielectric layer 22 for electrostatic adsorption is provided on the upper surface of the lower electrode 15, and the lower electrode 15 is connected to the positive side of the DC power supply 23 through the coil 24 for cutting off high-frequency components, and provides a pulse bias voltage of 20V to 1000V. voltage, the power supply 17 is connected through a DC blocking capacitor.

Rings 37A and 37B for suppressing discharge are provided around the processing chamber 10 . While seeking to increase the plasma density, adhesion of unwanted deposits on the outer portions of the discharge suppression rings 37A, 37B is minimized. Regarding the discharge suppression rings 37A and 37B of FIG. 14 , the diameter of the periphery of the discharge suppression ring 37A on the lower electrode side is smaller than the diameter of the periphery of the discharge suppression ring 37B on the top electrode side, so that the reaction around the sample The product distribution is the same.

In addition, as the material of the discharge suppressing rings 37A, 37B, at least the surface facing the processing chamber is made of a semiconductor or conductor such as carbon, silicon, or SiC. Moreover, the lower electrode side ring 37A utilizes a capacitor 19A to connect the 100K-13.56MHz discharge suppression ring with a bias power supply 17A, and the upper electrode side ring 37B can add part of the power of the high-frequency power supply 16 to reduce the impact caused by ion sputtering. effect and distribute to the deposits on the rings 37A, 37B, and also make it have the effect of removing fluorine.

13A and 13C in FIG. 14 are insulators made of materials such as alumina, and 13B is a conductive insulator such as SiC, glassy carbon, or Si.

When the conductivity of the rings 37A, 37B is low, the conductors such as metal are packed into the rings 37A, 37B, so that the distance between the surface of the rings and the built-in conductors is narrow. In this way, the high-frequency power is easily transferred from the rings 37A, 37B. Surface radiation, which can reduce the drop of sputtering effect.

The upper electrode cover 30 is usually fixed to the upper electrode 12 with bolts 250 only around its periphery. Gas is supplied from the gas supply unit 36 into the upper electrode cover through the gas introduction chamber 34 , the gas diffusion plate 32 , and the upper electrode 12 . In order to make it difficult for abnormal discharge to occur in the hole, the hole provided on the upper electrode cover 30 is made fine, with a diameter of 0.3 to 1 mm. The air pressure at the upper part of the upper electrode cover 30 ranges from a fraction of one air pressure to about one tenth. For example: for the upper electrode cover 30 with a diameter of 300 mm, a total force of 100 kg or more is applied. For this reason, the upper electrode cover 30 is formed in a convex shape with respect to the upper electrode 12 , and a gap of several hundred micrometers or more is formed near the center.

In this case, if the frequency of the high-frequency source 16 is increased above 30 MHz, the lateral resistance of the upper electrode cover 30 cannot be ignored, and the plasma density near the center partly decreases. In order to improve this situation, it is enough to fix the part of the upper electrode cover 30 near the center on the upper electrode. In the embodiment of FIG. Several parts in the center are fixed to the upper electrode 12 so that the distribution of the high frequency applied from the upper electrode 12 side becomes uniform.

In addition, the method of fixing at least the central part of the upper electrode cover 30 on the upper electrode 12 is not limited to the above-mentioned several fixing methods with bolts 251, and the upper electrode cover 30 and the upper electrode 12 can also be bonded together with a material having an adhesive effect. Glue all around or at least around the center.

In the embodiment of Fig. 14, the sample 40 as the object to be processed is installed on the lower electrode 15, and passes through the electrostatic chuck 20, that is, through the positive charge generated by the DC power supply 23 and the negative charge provided by the plasma on the electrostatic adsorption film 22. The Coulomb force generated between the two ends adsorbs the sample 40.

The function of this device is the same as that of the double-electrode plasma etching device shown in Fig. 1. When performing corrosion treatment, the sample 40 to be processed is placed on the sample table 15, fixed by electrostatic force, and the gas is supplied from the gas supply system 36. While supplying the processing gas to the processing chamber 10 at a predetermined flow rate, the vacuum pump 18 is used to evacuate the processing chamber 10 to reduce the pressure of the processing chamber 10 to a processing pressure of 0.5 to 4.0 Pa for the sample. Then turn on the high-frequency power supply 16, and apply a high-frequency voltage of 20 MHz to 500 MHz between the electrodes 12 and 15. It is best to apply a high frequency voltage of 30MHz to 100MHz to generate plasma. On the other hand, the pulse bias power supply 17 is applied to the lower electrode 15 with a positive pulse bias of 20V to 1000V with a period of 0.1 μs to 10 μs, preferably 0.2 μs to 5 μs, to control the plasma in the processing chamber 10 and to treat the sample. 40 for corrosion treatment.

By applying such a pulse bias voltage, the ions or ions and electrons in the plasma are accelerated and vertically injected into the sample to perform high-precision shape control or selectivity control. The characteristics required for the pulse bias power source 17 and the electrostatic adsorption film 22 are the same as those of the embodiment shown in FIG. 1, and the detailed description thereof will be omitted.

Other embodiments of the present invention will be described below based on FIGS. 15 to 17 . Although this embodiment is structurally the same as the two-electrode type plasma etcher shown in FIG. 1 , the structure of the magnetic field forming device 200 is different. The magnetic core 201 of the magnetic field forming device 200 is an eccentric type, and is driven by a motor 204 around an axis corresponding to the center position of the sample 40, and rotates at a speed of several tens of revolutions per minute. In addition, the magnetic core 201 is grounded.

In order to perform plasma treatment on the entire sample with high precision, so that the plasma generation near the periphery of the sample or its outer side is more than that near the center of the sample, the electron cyclotron resonance effect can be increased at the periphery or its outer side to make it more plasma than the central part. big. However, in the case of the embodiment of FIG. 1, as shown in FIG. 6, there is no ECR region near the center of the sample, and the plasma density is too low near the center.

In the embodiment of FIG. 15 , the distribution of the magnetic field changes with the rotation of the eccentric magnetic core 201 of the magnetic field forming device 200 . Near the center of the sample, if the time is t=0, t=T ₀ , the ECR zone is formed at a position lower than the sample surface, and when time T=1/2T ₀ , it is formed at a position higher than the sample surface formed at the position. The magnetic core 201 rotates at a speed of several to several tens of revolutions per minute. As a result, as shown in FIG. 17 , the average value of the magnetic field strength in the direction parallel to the sample surface between the two electrodes is approximately the same due to the time averaging effected by the rotation. , that is, the ECR region is formed at substantially the same height from the sample surface except for the peripheral portion of the sample.

In addition, in the magnetic core 201 part of Fig. 15, as shown by the dotted line, if the magnetic core forming the magnetic circuit on the side closer to the eccentric central core is reduced in thickness, and the magnetic core farther away from the eccentric central core is If the thickness of the magnetic core of the road is increased, the uniformity of the magnetic field will be further improved.

Further exemplary embodiments of the present invention are described below with reference to FIGS. 18 to 19 . The structure of this embodiment is the same as that of the two-electrode type plasma etching machine shown in FIG. However, the structure of the magnetic field forming device 200 is different. The magnetic core 201 of the magnetic field forming device 200 has a concave side 201A at a position corresponding to the center of the processing chamber, and has another side 201B at positions corresponding to both sides of the processing chamber. The magnetic flux B has an oblique direction component due to the side 201A of the concave surface. As a result, the distribution of the magnetic field changes. As shown in FIG. 19 , the magnetic field intensity of the component parallel to the sample surface is more uniform than that of the embodiment in FIG. 1 .

Next, other embodiments of the present invention will be described with reference to FIG. 20 . The structure of this embodiment is the same as that of the two-electrode type plasma etching machine shown in FIG. However, the structure of the magnetic field forming device 200 is different. The magnetic core 201 of the magnetic field forming device 200 is fixed, and forms a magnetic circuit together with the magnetic core 205 installed at a position corresponding to the center of the processing chamber. The magnetic core 205 and the insulator 203 rotate around the axis passing through the center of the side 201A simultaneously. Due to such a structure, it is the same as the embodiment of FIG. 15 . The average position of the ECR region near the center of the sample is formed at a position substantially at the same height as the sample surface. Right now. The ECR region is formed at substantially the same height as the sample surface over the entire surface of the sample.

Two-electrode plasma etching equipment according to other embodiments of the present invention will be described below with reference to FIG. 21 and FIG. 22 . The equipment of this embodiment is constituted like this, promptly the magnetic field forming device 200 has two pairs of coils 210 and 220 around the processing chamber 10, by sequentially switching the magnetic field on each pair of coils according to the directions of arrows 1, 2, 3, and 4 direction to form a rotating magnetic field. The center positions O-O of the coil 210 and the coil 220 are located on the side of the upper electrode 12 higher than the middle positions of the two electrodes 12 and 15 . In this way, the magnetic field intensity on the sample 40 is made to be 30 Gauss or less, preferably 15 Gauss or less.

The distribution of the magnetic field strength can be adjusted in order to increase the amount of plasma generated around the sample or its outer vicinity by appropriately selecting the positions and outer diameters of the coils 210 and 220 .

Two-electrode plasma etching equipment according to another embodiment of the present invention will be described with reference to FIG. 23 and FIG. 24. In this embodiment, as the magnetic field forming device 200, there are provided along the circumference of the circular processing chamber 10, in the horizontal plane by A pair of coils 210' arranged in an arc shape. Control the electric current flowing to the pair of coils 210' to (1) and (2) in the direction of the arrows shown in Figure 23, so that the polarity of the magnetic field changes in a certain period.

As shown by the dotted line in FIG. 24, in the vertical plane, since the magnetic flux B expands at the center of the processing chamber, the magnetic field intensity at the center of the processing chamber decreases. However, since the pair of coils 210' are bent along the processing chamber, the magnetic flux B is concentrated at the center of the processing chamber in the horizontal plane. Therefore, compared with the embodiment of Fig. 22, the magnetic field intensity at the central part of the processing chamber can be improved, that is, the embodiment of Fig. 23 can suppress the decline of the magnetic field strength at the central part of the processing chamber compared with the embodiment of Fig. 22, so that the The uniformity of the magnetic field intensity on the sample setting surface on the sample stage is further improved. And by changing the polarity of the magnetic field according to a certain period, the drift effect of E×B is reduced.

In addition, the same two pairs of coils as the embodiment of FIG. 22 may be used as the magnetic field forming device 200 .

The magnetic field forming device 200, as shown in FIG. 25, can also combine several linear coils arranged around the circular processing chamber 10 as a convex coil 210 "to replace the arc-shaped coil 210'. In this case , in the horizontal plane, the magnetic flux B is concentrated in the center of the processing chamber. The same effect as that of the embodiment in Fig. 23 can be obtained.

In order to make the central axes of the pair of coils close to the sample surface at the center of the processing chamber as in the embodiment of FIG. 26, the central axes of the coils can be placed obliquely. According to this embodiment, the magnetic field intensity at the central portion of the processing chamber can be increased and the magnetic field intensity at the peripheral portion of the processing chamber can be decreased, thereby improving the uniformity of the magnetic field on the sample placement surface of the sample stage. In addition, for the uniformity of the magnetic field intensity, a better method is to adjust the inclination angle θ of the central axis of the coil to a range of 5 to 25 degrees.

In addition, as shown in FIG. 27 , a coil 210B is attached next to a pair of coils 210A, and the currents of the two sets of coils are controlled. By doing so, the gradient of the magnetic field in the vicinity of the ECR resonance position is varied as the ECR resonance position changes, and the amplitude of the ECR resonance region is also varied. By optimizing the amplitude of the ECR resonance region for each process, an ion/atomic group ratio suitable for each process can be obtained.

In addition, the above-mentioned embodiments in FIGS. 23 to 27 can be properly combined as required, so that the uniformity and controllability of the magnetic field distribution can be further improved.

Next, a two-electrode plasma etcher according to another embodiment of the present invention will be described with reference to FIGS. 28 to 29 . In this embodiment, part of the process chamber wall is formed of semiconductor and is grounded. In addition, the magnetic field forming device 200 is provided with coils 230 and 240 around and above the processing chamber 10 . The direction of the magnetic flux B formed by the coil 230 and the direction of the magnetic flux B' formed by the coil 230 cancel each other at the center of the processing chamber 10 as indicated by the arrows, and overlap each other around and outside the processing chamber 10. As a result, the magnetic field intensity distribution on the sample surface becomes the state shown in FIG. 29 . Furthermore, in the portion of the surface on which the sample 40 is placed, the direction of the electric field component between the upper electrode 12 and the lower electrode 15 is parallel to the direction of the magnetic field component. On the other hand, a longitudinal magnetic field component perpendicular to the transverse electric field component is generated around the upper electrode 12 and at the portion between the upper electrode 12 and the processing chamber wall outside the surface where the sample 40 is placed.

Therefore, if the embodiment of Fig. 28 is used, the electron cyclotron resonance effect near the center of the sample can be reduced, thereby enhancing the plasma generation around the sample and its outer vicinity. In this way, by further increasing the plasma generation around the sample and its outer vicinity, the plasma density distribution can be made uniform.

Next, another embodiment of the present invention will be described with reference to FIG. 30 . On the two-electrode plasma etching machine shown in Fig. 1, when the high-frequency power f1 applied to the electrode 12 by the high-frequency power supply 16 cannot obtain sufficient ion energy, by adding, for example, a frequency below 1 MHz from the low-frequency power supply 163 to the upper electrode 12 The high frequency f3 is used as a bias voltage to increase the ion energy by about 100-200V. In addition, 164 and 165 are filters.

An example of the present invention in terms of a two-electrode plasma etching machine of a non-magnetic field type will be described below with reference to FIG. 31. FIG.

As mentioned above, in order to improve the microfabrication processability of the sample, it is better to use a higher frequency power supply as the high frequency power supply 16 for plasma generation, so as to achieve the stability of the discharge in the low pressure area. In the embodiment of the present invention, the sample processing pressure in the processing chamber 10 is set at 0.5-4.0 Pa. By changing the gas pressure in the processing chamber 10 to a low pressure below 40 mTorr, the impact of ions in the space charge layer is reduced, so when the sample 40 is processed, the directionality of ions is enhanced, and vertical microfabrication can be performed. In addition, if it is 5 mTorr or less, in order to obtain the same processing speed, the exhaust device and the high-frequency power supply must be enlarged, and at the same time, there is a tendency that the temperature of the electrons will rise and dissociate more than necessary, resulting in a decrease in characteristics.

In general, there is such a relationship between the frequency of a plasma generating power supply using a pair of two electrodes and the minimum air pressure at which discharge can be stably performed that, as shown in Fig. 32, the higher the frequency of the power supply, the closer the distance between the electrodes. The larger the pressure, the lower the minimum air pressure for stable discharge. In order to avoid the adverse effects of deposits on the surrounding walls and suppress the discharge ring 37 and effectively use the upper electrode cover 30, the receiver cover 39 and the photosensitive glue in the sample to remove Fluorine and oxygen are preferably not more than 25 times the mean free path at the maximum pressure of 40 mTorr, and the distance between electrodes is set to not more than 50 mm. Furthermore, if the distance between the electrodes is not more than 2 to 4 times (4 mm to 8 mm) the mean free path at the maximum gas pressure (40 mTorr), stable discharge becomes difficult.

In the embodiment shown in Fig. 31, since the high-frequency power supply 16 for plasma generation uses a high-frequency power of 20 MHz to 500 MHz, preferably a high-frequency power of 30 MHz to 200 MHz, even if the gas pressure in the processing chamber is changed to 0.5 to 4.0 The low pressure of Pa can also obtain stable plasma, and can improve the microfabrication process. Moreover, by using such high-frequency power, the dissociation of the plasma is improved, and the selection and control of the sample processing are easier.

In the embodiments of the present invention described above, it has also been considered that interference may also occur between the output of the pulse bias power supply and the output of the plasma generating power supply. Therefore, this countermeasure will be discussed below.

First, the pulse width is T ₁ , the pulse period is T ₀ , an ideal rectangular pulse with infinite rising/falling speed, as shown in Figure 33, within the frequency range of f≤3f ₀ (f ₀ =1/T ₁ ) Contains 70-80% power. The actually added waveform has limited rising/falling speed, and the power concentration has been further improved, and it can reach more than 90% power in the frequency range of _f≤3f0 .

In order to uniformly add the pulse bias voltage with 3f ₀ high frequency components to the sample surface. It is best to set the opposite electrode substantially parallel to the sample. For 3f ₀ obtained by the following equation 3, the frequency components in the range of f≤3f ₀ are grounded.

If T ₁ =0.2μs, then 3f ₀ =3·10 ⁶ /0.2=15MHz

If T ₁ =0.1μs, then 3f ₀ =30MHz...Formula 3

The embodiment shown in FIG. 31 takes countermeasures against the above-mentioned interference between the output of the pulse bias voltage power supply and the output of the plasma generating power supply. Namely on this plasma etcher. The plasma generating high-frequency power supply 16 is connected to the upper power supply 12 facing the sample. In order to make the upper electrode 12 reach the ground level of the pulse bias voltage, the frequency _f1 of the high-frequency power supply 16 for plasma generation is increased to the above-mentioned _3f0 or higher, and the frequency _f≤f1 is connected between the above-mentioned electrode 12 and the ground level. The band stopper 141 has a large impedance and a small impedance at other frequencies.

On the other hand, the impedance is low in the vicinity of f= _f1 , and the bandpass filter 142 with high impedance is provided between the sample stage 15 and the ground level at other frequencies. With this structure, the interference between the output of the pulse bias power supply 17 and the output of the plasma generating power supply 16 can be controlled to a level without any problem, and an appropriate bias voltage can be applied to the sample stage 40 .

Fig. 34 is an example of applying the present invention to an inductive coupling discharge method non-magnetic field type plasma etching machine in the external energy supply discharge method. 52 is a planar coil, and 54 is a high-frequency power supply for adding a 10MHz-250MHz high-frequency voltage to the planar coil. Compared with the method shown in Fig. 10, the inductive coupling discharge method can realize stable plasma generation under the condition of low frequency and low voltage. On the contrary, as shown in FIG. 1 , thus dissociation, so the output of the high-frequency power supply 1 is modulated by the high-frequency power supply modulation signal source 161, and unnecessary dissociation can be prevented. The processing chamber 10 as a vacuum container is provided with a sample stage 15 for placing a sample 40 on its electrostatic adsorption film 22 .

When performing etching treatment, the sample 40 to be processed is placed on the sample stage 15, fixed with electrostatic power, and the processing gas is introduced into the processing chamber 10 at a prescribed flow rate from the gas supply system (not shown). , while using a vacuum pump to depressurize the pressure of the processor 10 to 0.5-4Pa. Then, a high-frequency voltage of 13.56 MHz is applied to the high-frequency power supply 54 to generate plasma in the processing chamber 10, and the sample 40 is etched with the plasma. In addition, during etching, a pulse bias voltage with a period of 0.1 μs to 10 μs, preferably 0.2 μs to 5 μs is applied to the lower electrode 15 . The width of the pulse bias is as described in the embodiment of FIG. 1 due to the different ranges of the film types. By adding a pulse bias, the ions in the plasma are accelerated and incident vertically on the sample to control the high precision or selectivity of the shape. Thus, even if the photoresist mask pattern is extremely fine, it can be etched with high precision.

In addition, as shown in FIG. 35 , in an inductively coupled discharge type non-magnetic field plasma etching machine, a Faraday shielding plate 53 with a gap and a 0.5mm-5mm The insulating plate 54 for the protection of the thin shielding plate can also ground the Faraday shielding plate. Because the Faraday shielding plate 53 is set, the capacitance component between the coil and the plasma is reduced, the energy of the ions colliding with the quartz plate under the coil 52 in Fig. 34 and the insulating plate 54 for shielding plate protection can be reduced, and the quartz plate is reduced. The damage of the board and the insulation board, at the same time, it can also prevent the mixing of foreign matter in the plasma.

In addition, since the Faraday shield 53 also serves as the ground electrode of the pulse bias power supply 17, a pulse bias can be uniformly applied between the sample 40 and the Faraday shield 53. In this case, it is not necessary to install a filter on the upper electrode or the sample stage 15 .

Fig. 36 is a front view of a longitudinal section of a part of the apparatus when the present invention is applied to a microwave plasma processing apparatus. On the sample stage 15 that places the sample 40 on the electrostatic adsorption film 22, that is, on the lower electrode 15, a pulse bias power supply 17 and a DC power supply 13 are connected. 41 is a magnetron as a microwave oscillation source, 42 is a microwave waveguide, 43 is a quartz plate that vacuum-seals the processing chamber 10 and supplies microwaves to the processing chamber 10 . 47 is a first helical coil for providing a magnetic field, 48 is a second helical coil for providing a magnetic field, and 49 is a supply system for processing gas, which supplies the processing gas used for etching, film formation, etc. to the processing chamber 10 . The processing chamber 10 is evacuated by a vacuum pump (not shown). The necessary characteristics of the bias power supply 17 and the electrostatic chuck 20 are the same as those of the embodiment shown in FIG. 1 . Details are omitted.

When performing etching treatment, the sample 40 to be processed should be placed on the sample stage 15, fixed by electrostatic force, and the processing gas is introduced into the processing chamber 10 from the gas supply system 49 according to a predetermined flow rate, while using a vacuum pump Vacuuming is performed to reduce the pressure of the processing chamber 10 to 0.5-4.0Pa. Then, the magnetron 41 and the first and second helical coils 47 and 48 are switched on, and the microwave generated by the magnetron 41 is guided into the processing chamber 10 through the waveguide 42 to generate plasma. The sample 40 was subjected to etching treatment with this plasma. In addition, during etching, a pulse bias voltage with a period of 0.1 μs to 10 μs, preferably 0.2 μs to 5 μs should be applied to the lower electrode 15 .

Applying this kind of pulse bias can accelerate the ions in the plasma and incident them vertically on the sample, so as to achieve the purpose of controlling the shape or selection ratio with high precision. In this way, even if the photoresist mask pattern of the sample is extremely fine, high-precision etching processing corresponding to the mask pattern can be carried out through vertical incidence.

Furthermore, in the plasma etching apparatus of the present invention shown in FIG. 1, the DC voltage of the electrostatic adsorption circuit and the pulse voltage of the pulse bias power supply circuit can be superimposedly generated to form a general-purpose circuit. At the same time, the electrostatic adsorption circuit and the pulse bias power supply circuit can also be designed as separate electrodes, so that the pulse bias does not affect the electrostatic adsorption.

The electrostatic adsorption circuit in the embodiment of the plasma etching device shown in FIG. 1 can also be replaced by other devices, such as a vacuum adsorption device.

Equipped with the above-mentioned plasma processing apparatus of the electrostatic adsorption circuit and the pulse bias circuit of the present invention, if the CVD gas etc. are introduced instead of the etching gas, it is not only applicable to the above-mentioned etching processing apparatus but also applicable to CVD and other apparatuses. Plasma treatment device.

Next, introduce another embodiment of the plasma etching apparatus that utilizes other embodiments of the present invention shown in FIG. 37 to overcome the shortcomings of the examples, control the quality and quantity of ions and atomic groups generated, and be able to perform ultrafine plasma processing.

That is, on the upstream side of the vacuum processing chamber containing the sample, a place where the first plasma can be generated is set at a place different from the vacuum processing chamber, and the quasi-stable atoms generated at this place are injected into the vacuum processing chamber, and then A second plasma is generated by the vacuum processing chamber. In the plasma etching apparatus shown in FIG. 1, a gas supply unit 60 for ions and radical sources and a plasma generation chamber 62 for generating metastable atoms are separately prepared. In addition, on the upper electrode 12, in addition to the passage for introducing the gas containing quasi-stable atoms into the vacuum processing chamber, there is also an introduction passage connected to all the sources for ions and radicals.

The characteristics of this embodiment are as follows:

1. The gas provided by the gas supply unit 36 that produces quasi-stable atoms is applied to the plasma generation chamber 62 for producing quasi-stable atoms, and the high-frequency power is applied for plasmaization, and the predetermined quasi-stable atoms are generated in advance according to the required amount. It is injected into the processing chamber 10 . In order to make the plasma generating chamber 62 for producing quasi-stable atoms efficiently produce quasi-stable atoms, the pressure in the chamber should be set at a high pressure of hundreds of mTorr-tens of Torr.

② On the other hand, the gas supplied from the ion and radical source supply unit 60 is to flow into the processing chamber 10 .

③Use the power source 16 for plasma generation to output low-power high-frequency to generate plasma in the processing chamber 10. Due to the implantation of metastable atoms, ions can be efficiently generated even with low-energy electrons below 5eV, so a plasma with a low electron temperature (below 6eV, ideally 4eV or below) and a large reduction in high-energy electrons exceeding 15V can be obtained. Therefore, the gas for the radical source does not cause excessive dissociation, and the necessary quality and quantity can be ensured. On the other hand, the amount of ions can be controlled by the mass of metastable atoms generated in the plasma generation chamber 62 for generating metastable atoms and the gas beam for ion source supplied from the gas supply unit 60 for ion and radical source.

In this way, the quality and quantity of ions and atomic clusters can be controlled, so that it can also get good performance in extremely fine plasma treatment. As the gas used as the source of atomic groups, as needed, in CHF ₃ , CH ₂ F ₂ , C ₄ F ₈ or CF ₄ and other fluorocarbon gases, mix corresponding C, H-containing gases (C ₂ H ₄ , CH ₄ , CH ₃ OH, etc.). As the gas for generating quasi-stable atoms, one to two rare gases are used as the base gas. As the ion source gas, since a rare gas or the like having the following properties is used, ions can be efficiently generated.

As for the energy level of the gas used, the gas for the ion source has a lower ionization energy level than the energy level of the above-mentioned metastable atoms, or the ionization energy level of the gas for the ion source is higher but the difference is small (5 eV or less).

As the gas for the ion source, its kind may not be specially added, and the above-mentioned gas for generating metastable atoms and gas for radical source may be used instead, but the performance is reduced.

Next, shown in FIG. 38 is another embodiment of using the present invention to control the quality and quantity of ions and radicals generated. It is the same with the basic idea of Fig. 37, but in Fig. 37, the distance between the plasma chamber 62 and the vacuum processing chamber 10 that produces the quasi-stable atoms is very long, and the attenuation of the quasi-stable atoms therebetween is large, and Fig. 38 is Examples of countermeasures taken against this situation. 41 is a magnetron as a microwave oscillation source, 42 is a microwave waveguide, 43 is a quartz plate that vacuum-seals the first plasma generation chamber 45 and allows microwaves to pass therethrough, and 44 is a quartz plate for dispersing gas. In the first plasma generating chamber 45, plasma is generated at a gas pressure ranging from several hundreds of mTorr to several tens of Torr by using the above-mentioned microwaves, and metastable atoms are generated.

In Fig. 38, compared with Fig. 37, the distance between the place where the quasi-stable atoms are generated and the vacuum processing space can be shortened, so the quasi-stable atoms can be injected into the vacuum processing chamber in a high-density state, and the vacuum processing chamber can be increased by 10 The amount of ions in . The processing chamber 10 maintains a pressure of 5-50 mTorr, and a high-density, low-electron-temperature plasma of 10 ¹⁰ to 10 ¹¹ /cm ³ is generated by a high-frequency power supply 16 above 20 MHz, preferably below 3 eV, which can prevent the required dissociation energy CF ₂ dissociates at 8eV or higher to ionize the gas for the ion source. As a result, on the surface of the sample 40, after the ions accelerated by the bias power supply 17 at hundreds of volts were incident, the main reactions that occurred were as follows:

Si and SiN, which are the underlying materials, are not etched in CF ₂ , so it is possible to etch an oxide film with a high selectivity ratio.

Also, since a part of CF ₂ is dissociated, F increases, which can be reduced by the upper electrode cap 30 formed of silicon, carbon, or SiC (silicon carbide) or the like.

As described above, by adjusting the gas for the radical source and the gas for the ion source, the ratio of ions and radicals in the processing chamber 10 can basically be independently controlled, and the reaction on the surface of the sample 40 can be easily controlled to a desired level. .

In the present invention, the plasma processing device equipped with an electrostatic adsorption circuit and a pulse bias circuit adds changes such as replacing etching gas with CVD gas, so it is not only used for the above-mentioned etching processing, but also can be used for other plasma processing such as CVD devices. device.

Next, Fig. 39 is another embodiment of the present invention for independent control of ions and atomic groups. In Fig. 39, the gas containing C and H (C ₂ H ₄ , CH ₃ OH, etc.) is mixed into the fluorocarbon gas such as CHF ₃ , CH ₂ F ₂ , C ₄ F ₈ or CF ₄ as needed, From the part constituting FIG. 39A , it enters into the plasma generation chamber 62 for generating radicals through the valve 70 .

In the plasma generation chamber 62 that generates atomic radicals, the output of an RF (radio frequency) power supply 63 of several megahertz (MHz) or even tens of megahertz (MHz) is added to the coil 65, and the air pressure of hundreds of mTorr to tens of Torr is used to generate Plasma, mainly produces CF ₂ radicals. Simultaneously produced CF ₃ , F and other substances are reduced by the H component.

However, since it is difficult to greatly reduce components such as CF and O in the plasma generation chamber 62 where radicals are generated, an unnecessary component removal chamber 65 is provided behind it. The inner wall of the removal chamber is made of carbon and silicon (Si)-containing materials (carbon, silicon, silicon carbide, etc.) to reduce unnecessary components or convert them into other gases with less adverse effects. The outlet of component removal chamber 65 is not required, and valve 71 is connected to supply the main mixed gas with _CF2 component.

In addition, between the valve 70 and the valve 71, a lot of deposits such as deposits are accumulated, so it needs to be cleaned or replaced frequently. Therefore, an exhaust device 74 is connected via a valve 72 in order to facilitate the atmosphere release and replacement operations, and also to shorten the evacuation time at restart. The exhaust device 74 may also be used as an exhaust device for the processing chamber 10 or the like.

In addition, the gas (rare gas such as argon, xenon, etc.) B for the ion source is connected to the outlet of the aforementioned valve 71 through the valve 73, so that the gas is supplied into the processing chamber.

The processing chamber 10 maintains a pressure of 5-40 mT, and utilizes a modulated high-frequency power supply 16 above 20 MHz to generate high-density and low-electron temperature plasma of 10 ¹⁰ -10 ¹¹ /cm ³ at 5 eV, ideally below 3 eV. Dissociation of CF ₂ that requires 8eV or more is required to prevent dissociation energy, and ionization of the ion source gas can be performed. As a result, on the surface of the sample 40, after the ions accelerated by the bias power supply 17 at hundreds of volts were incident, the following reactions mainly occurred:

In this way, Si and SiN, which are the underlying materials, will not be etched by CF ₂ , so high-selectivity oxide film etching can be performed.

In addition, F (fluorine) increases due to the dissociation of a part of CF ₂ (carbon fluoride), but the upper electrode cover 30 formed of silicon, carbon, or silicon carbide (SiC) decreases F (fluorine) .

As described above, the gas A for regulating the radicals and the gas B for the ion source can generally independently control the ratio of ions and radicals in the processing chamber 10 . The reaction of the sample 40 surface is easily controlled at its desired level. In addition, unnecessary deposits and the like are removed by using the unnecessary component removal chamber 65, and these unnecessary components are not brought into the processing chamber 10 as much as possible, so the deposits in the processing chamber 10 are greatly reduced, and the processing chamber is opened as The frequency of atmospheric state sweeps has also been drastically reduced.

Next, shown in Fig. 40 are other examples of independent control of ions and atomic groups. Hexafluoropropylene gas (CF ₃ CFOCF ₂ , hereinafter abbreviated as HFPO), passes through the valve 70 from A, leads to the heating pipeline part 66, passes through the excess (unnecessary) component removal chamber 65 and the valve 71, mixes with the ion source gas B, and sends to Direction to the processing chamber 10. At the heating pipe part 66, HFPO is heated to 800°C-1000°C to decompose it to generate CF ₂ .

CF ₃ CFO is a relatively stable substance that is not easy to decompose, but it will partially decompose to generate unnecessary oxygen (O) and fluorine (F). Therefore, an excess component removal chamber 65 is installed behind the heating tube part 66 to remove excess ingredient, or convert it into a substance that has no adverse effects. A part of CF ₃ CFOCF ₂ that is not decomposed flows into the processing chamber 10 , but it is not a problem because it does not dissociate in plasma with a low electron temperature of 5 eV or less.

The usage of the valve 72 and the exhaust device 74 and the reaction in the processing chamber 10 are the same as those in the case of FIG. 39 .

The plasma processing device with the electrostatic adsorption circuit and the pulse bias circuit of the present invention, if the etching gas is replaced by CVD gas, is not only used for the above-mentioned etching treatment, but also can be used for other plasma treatments such as CVD. device.

Claims (31)

1. A plasma processor, comprising:

a vacuum processing chamber;

a plasma generating device comprising a pair of electrodes;

a sample stage having a sample placing surface for placing a sample to be processed in the vacuum processing chamber; and

the plasma processor of the pressure reducing device for vacuum-reducing the vacuum processing chamber is characterized by further comprising:

a high-frequency power supply for applying a high-frequency power of a VHF band of 30MHz to 300MHz between the pair of electrodes; and

a magnetic field forming device for forming a static magnetic field or a low-frequency magnetic field in a direction intersecting with an electric field generated between or in the vicinity of the pair of electrodes by the high-frequency power supply,

an electron cyclotron resonance region is formed between the two electrodes by the interaction between the magnetic field and the electric field.

2. A plasma processor, comprising:

a vacuum processing chamber;

a plasma generating device including a pair of electrodes;

a sample stage which also serves as one of the electrodes and on which a sample to be processed in the vacuum processing chamber is placed; and

the plasma processor of the pressure reducing device for vacuum-pumping and pressure-reducing the vacuum processing chamber is characterized by further comprising:

a high frequency power supply for applying a VHF band power supply of 50MHz to 200MHz between the pair of electrodes; and

a magnetic field forming device for forming a static magnetic field of 17 Gauss or more and 72 Gauss or less or a low-frequency magnetic field in a direction intersecting with an electric field generated between the pair of electrodes or in the vicinity thereof by the high-frequency power supply,

the magnetic field forming means is set so that the maximum component of the magnetic field in the direction along the surface of the sample stage is positioned on the opposite side of the sample stage, i.e., at a position exceeding the center of the two electrodes,

an electron cyclotron resonance region is formed between the pair of electrodes by the interaction between the magnetic field and the electric field.

3. The plasma processor according to claim 1 or 2, wherein the intensity of the magnetic field formed by the magnetic field forming means is adjusted so that a component of the magnetic field parallel to the surface of the sample is 30 gauss or less.

4. A plasma processor, comprising:

a vacuum processing chamber;

a plasma generating device including a pair of electrodes; and

in a plasma processing machine having a sample stage (which also serves as one of the electrodes and is used for placing a sample to be processed in the vacuum processing chamber),

the electrodes are composed of a 1 st electrode connected to a high frequency power supply and a 2 nd electrode, the 2 nd electrode is also used as the sample stage and is connected to a bias power supply for controlling ion energy, the distance between the pair of electrodes is 30-100mm,

further comprising:

a pressure reducing device for reducing the pressure in the vacuum processing chamber to 0.4Pa-4 Pa;

the high-frequency power supply is used for adding a VHF frequency band power supply of 30MHz-300MHz between the pair of electrodes; and

a magnetic field forming means for forming a static magnetic field or a low-frequency magnetic field portion of 10 Gauss or more and 110 Gauss or less in a direction intersecting with the electric field between the pair of electrodes or in the vicinity thereof,

an electron cyclotron resonance region is formed on the 1 st electrode surface or on the 1 st electrode side beyond the center position of the two electrodes by the interaction between the magnetic field and the electric field generated by the high-frequency power supply.

5. The plasma processor according to claim 1, 2 or 4, wherein the density or direction of said magnetic field formed by said magnetic field forming means is adjusted so that said electron cyclotron resonance effect is larger at the periphery and outside of the sample than at the center of said sample, and further, the plasma density is made uniform at positions corresponding to said entire sample placement surface.

6. The plasma processor according to claim 4, wherein the magnetic core in the magnetic field forming device is eccentrically rotated with respect to the center of the sample surface to change the magnetic field, thereby continuously changing the distance of the cyclotron resonance region from the sample.

7. A plasma processor, comprising:

a vacuum processing chamber;

a plasma generating device comprising a pair of electrodes;

a sample stage having a sample placing face for placing a sample to be processed in the vacuum processing chamber; and

in a plasma processor having a vacuum reducing device for vacuum-reducing the vacuum processing chamber, characterized in that,

the electrode comprises the following components: a 1 st electrode connected with a high-frequency power supply, a 2 nd electrode also used as a sample stage, and a processing chamber wall part which is positioned at the outer side of the periphery of the 1 st electrode and is grounded,

the plasma processor further has:

a high-frequency power supply for applying a high-frequency power of a VHF band of 30MHz to 300MHz between the pair of electrodes and between the 1 st electrode and the wall portion of the processing chamber; and

a magnetic field forming device for forming a static magnetic field or a low-frequency magnetic field portion of 10 Gauss to 110 Gauss, the magnetic fields being formed in such directions as to cancel each other near the center of the processing chamber and overlap each other around and outside the processing chamber,

an electron cyclotron resonance region is formed around the sample placement surface and in the vicinity of the outer side of the sample placement surface by the interaction between the magnetic field and the electric field generated by the high-frequency power supply.

8. The plasma processor according to claim 7, wherein the magnetic field forming means has a plurality of coils and is installed around the processing chamber so that magnetic fluxes are offset from each other in the vicinity of the center of the sample and overlap each other around the sample and outside thereof.

9. The plasma processor according to claim 4, wherein the pulse bias voltage having a period of 0.2 to 5 μ s and a duty ratio of the forward pulse portion of 0.4 or less is applied to the specimen through the capacitive element as the bias current for controlling the ion energy.

10. The plasma processor according to claim 1, 2 or 4, wherein:

an electrostatic adsorption device for fixing the sample on the sample stage by electrostatic adsorption force;

a pulse bias device connected to the sample stage for applying a pulse bias to the sample stage; and

and a voltage suppressing device for suppressing a voltage rise corresponding to the electrostatic adsorption capacity of the electrostatic adsorption device in response to the application of the pulse bias.

11. The plasma processor according to claim 10, wherein the voltage suppressing means is configured to suppress a voltage variation generated in an electrostatic adsorption film of the electrostatic adsorption device in one cycle of the pulse to be below 1/2 of the pulse bias voltage.

12. A plasma processing method is characterized by comprising the following steps:

a vacuum processing chamber;

a plasma generating device comprising a pair of electrodes;

a sample stage which also serves as one of the electrodes and on which a sample to be processed in the vacuum processing chamber is placed; and

the sample processing method of the plasma processor of the pressure reducing device (for reducing the pressure in the vacuum processing chamber) comprises the following program steps:

reducing the pressure in the vacuum processing chamber by using a pressure reducing device;

forming a static magnetic field or a low-frequency magnetic field portion of 10 gauss or more and 110 gauss or less in a direction intersecting the electric field between the pair of electrodes by a magnetic field forming means;

a VHF band power supply of 30MHz-300MHz is added between the pair of electrodes by a high frequency power supply, and an electron cyclotron resonance region is formed between the two electrodes by the interaction of the magnetic field and an electric field formed by the high frequency power supply;

the sample is processed by plasma generated by the electron cyclotron resonance.

13. A plasma processing method for a sample in a plasma processor having a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generator including a pair of electrodes,

the electrode is configured as a pair of electrodes, including: a 1 st electrode connected to the high-frequency power supply, and a 2 nd electrode also used as the sample stage and connected to a bias power supply for ion energy control, wherein the distance between the pair of electrodes is 30-100mm,

comprises the following steps:

reducing the pressure in the vacuum processing chamber to 0.4-4Pa by using a pressure reducing device;

forming a static magnetic field or a low-frequency magnetic field portion of 10 gauss to 110 gauss in a direction intersecting the electric field between the pair of electrodes by a magnetic field forming means;

applying a VHF power source of 30MHz to 300MHz between the pair of electrodes by a high frequency power source, and forming an electron cyclotron resonance region between the pair of electrodes by an interaction between the magnetic field and an electric field generated by the high frequency power source;

the sample is processed by plasma generated by the electron cyclotron resonance.

14. A plasma processor comprising a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generator including a high-frequency power source, the plasma processor comprising: an electrostatic adsorption device for fixing the sample on the sample stage by electrostatic adsorption force; and

a pulse bias device for applying a pulse bias to the sample,

further, a high-frequency voltage of 10MHz to 500MHz is applied as the high-frequency power source, and the pressure in the vacuum processing chamber is reduced to 0.5Pa to 4 Pa.

15. A plasma processor, comprising:

a pair of oppositely mounted electrodes, one of which is provided with a sample;

a gas introducing device for introducing an etching gas into the processing chamber (into the ambient gas) in which the sample is placed;

an exhaust device for reducing the pressure in the processing chamber to 0.5-4 Pa;

a high-frequency power supply for applying a high-frequency voltage of 10MHz to 500MHz to the pair of opposing electrodes;

a plasma generating device for converting the etching gas into plasma (plasmatizing) under the pressure;

a pulse bias device for applying a pulse bias to the 1 electrode when the sample is etched;

the insulating film in the sample is subjected to plasma treatment.

16. A plasma processor is provided, which is capable of processing a plurality of plasma,

a plasma processor comprising a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating device, the plasma processor comprising:

an electrostatic adsorption device for fixing the sample on the sample stage by electrostatic adsorption force;

a pulse bias device connected to the sample stage for applying a pulse bias to the sample stage;

a voltage suppressing device for suppressing a voltage rise corresponding to an electrostatic adsorption capacity of the electrostatic adsorption device in response to application of a pulse bias;

the voltage suppressing device is configured such that a voltage change generated in an electrostatic adsorption film of the electrostatic adsorption device in one cycle of a pulse is suppressed to 1/2 or less of the pulse bias.

17. A plasma processor characterized by comprising:

a pair of electrodes having a gap of 10-50mm and disposed facing each other;

electrostatic adsorption means for fixing a sample to one of the electrodes by means of electrostatic adsorption force;

a gas introducing device for introducing an etching gas into a gas around the sample in the processing chamber in which the sample is placed;

an exhaust means for reducing the air pressure around the sample to 0.5-4.0 Pa;

a plasma generating device for ionizing the etching gas under the pressure by using high-frequency power of 10MHz-500 MHz; and

a pulse bias means for applying a pulse bias to an electrode on which the sample is placed;

further, the insulating film in the sample is subjected to plasma treatment.

18. The plasma processor of claim 16 or 17,

a voltage suppressing means for suppressing a voltage rise generated corresponding to the electrostatic adsorption capacity of the electrostatic adsorption means with the application of the pulse bias,

the period of the pulse bias is set so that the voltage change caused by the electrostatic adsorption film of the electrostatic adsorption device in one period of the pulse is suppressed to 1/2 or less of the pulse bias by the voltage suppressing means.

19. A plasma processing method is characterized by comprising the following processing program steps:

placing the sample on an electrode in a vacuum processing chamber;

fixing the sample on the electrode by using electrostatic adsorption force;

introducing a process gas into the process chamber containing the sample;

reducing the gas pressure around the sample to a pressure required for sample processing;

plasmatizing the process gas at the pressure;

processing the sample with the plasma;

a pulsed bias is applied to the sample.

20. A plasma processing method is characterized by comprising the following processing program steps:

placing the sample on one of a pair of oppositely disposed electrodes having a gap of 10mm to 50 mm;

fixing the sample placed on the electrode to the electrode by using electrostatic adsorption force;

feeding an etching gas into the ambient gas in which the sample is placed;

reducing the pressure of said ambient gas to 0.5-4.0 Pa;

applying a high-frequency power of 10MHz to 500MHz to plasmatize the etching gas under the gas pressure;

etching the sample with the plasma;

a pulse bias is applied to the one electrode while the etching is performed,

thus, the insulating film in the sample is subjected to plasma treatment.

21. A plasma processing method is characterized by comprising the following processing program steps:

placing the sample on one of a pair of electrodes mounted in a vacuum processing chamber;

fixing the sample to the electrode by electrostatic attraction;

sending the corrosive gas into the ambient gas in which the sample is placed;

reducing the pressure of said ambient gas;

plasmatizing the etching gas at the low pressure;

etching the sample by using the plasma;

a pulsed bias voltage is applied to the sample,

in this way, the voltage variation of the electrostatic adsorption film of the electrostatic adsorption device in one pulse period when the pulse bias is applied is suppressed to 1/2 or less of the pulse bias.

22. A plasma processing method is characterized by comprising the following processing program steps;

placing the sample on one of two opposing electrodes;

fixing the placed sample on the electrode by using electrostatic adsorption force;

supplying an etching gas into the gas in the processing chamber containing the sample;

carrying out plasma treatment on the fed corrosive gas;

etching the sample by using the plasma;

when the etching is carried out, a pulse bias voltage of a pulse width of 250V-1000V and a duty ratio of 0.05-0.4 is applied to the one electrode,

thus, the insulating film in the sample is subjected to plasma treatment.

23. A plasma processor is provided, which is capable of processing a plurality of plasma,

the plasma processing apparatus includes a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating device, and further includes:

an electrostatic adsorption device for fixing the sample on the sample stage by electrostatic adsorption force;

a biasing device for applying a bias to the sample stage;

a radical supply device having a device for decomposing a gas for generating radicals in advance, and supplying a required number of radicals into the vacuum processing chamber;

a gas supply device for supplying a gas for generating ions into the vacuum processing chamber; and

a plasma generating device for generating plasma in the vacuum processing chamber,

and, using SiO₂The sample was obtained.

24. A plasma processing machine having a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating device, characterized by further comprising:

an electrostatic adsorption device for fixing the sample on the sample table by means of electrostatic adsorption force;

a pulse bias device for applying a pulse bias to the sample;

a plasma supply device for radical generation for plasmatizing a gas for radical generation in advance in the vacuum processing chamber and supplying a required number of radicals;

a plasma generator for generating plasma by supplying an ion generating gas into the vacuum processing chamber,

and, using SiO₂The samples were used as described above.

25. A plasma processing machine having a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating device including a high-frequency power source, characterized by further comprising:

an electrostatic adsorption device for fixing the sample on the sample stage by electrostatic adsorption force;

a pulse bias device for applying a pulse bias to the sample;

a plasma supply device for radical generation for plasmatizing a gas for radical generation in advance in the vacuum processing chamber and supplying a required number of radicals;

a plasma generator for generating plasma in the vacuum processing chamber by supplying a gas for generating ions,

and, a high frequency voltage of 10MHz to 500MHz is applied to the high frequency power source, and the pressure in the vacuum processing chamber is reduced to 0.5 to 4.0 Pa.

26. A plasma processing apparatus having a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating device, the plasma processing apparatus comprising:

an electrostatic adsorption device for fixing the sample on the sample table by means of electrostatic adsorption force;

a plasma supply device for radical generation for plasmatizing a gas for radical generation in advance in the vacuum processing chamber and supplying a required number of radicals;

a plasma generator for supplying a gas for generating ions and generating plasma in the vacuum processing chamber;

a pulse bias device connected with the sample platform for applying pulse bias to the sample platform; and

and a voltage suppressing device for suppressing a voltage rise corresponding to an electrostatic adsorption capacity of the electrostatic adsorption device with the application of the pulse bias.

27. A plasma processing machine having a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating device, characterized by further comprising:

an electrostatic adsorption device including an electrostatic adsorption film provided on the sample stage for fixing the sample to the sample stage by an electrostatic adsorption force;

a plasma supply device for radical generation for plasmatizing a gas for radical generation in advance in the vacuum processing chamber and supplying a required number of radicals;

a plasma generator for supplying a gas for generating ions and generating plasma in the vacuum processing chamber;

a pulse bias device connected to the sample stage for applying a pulse bias to the sample stage;

a voltage suppressing means for suppressing a voltage generated between both ends of the electrostatic adsorption film in accordance with the application of the pulse bias,

the voltage suppressing device suppresses a voltage generated by the electrostatic attraction film of the electrostatic attraction device to 1/2 or less of the pulse bias.

28. A plasma processing method is characterized by comprising the following processing program steps:

placing the sample on one of a pair of opposing electrodes;

fixing the sample on the electrode by electrostatic adsorption force;

preliminarily plasmatizing a radical generating gas in the ambient gas in which the position of the sample is placed and fixed, and supplying a required numberof radicals;

supplying an ion generating gas to the ambient gas at the position;

reducing the ambient air pressure at said location to 0.5-4.0 Pa;

applying a high-frequency voltage of 10MHz to 500MHz to the pair of opposing electrodes, and plasmatizing the supplied ion generating gas under the above-mentioned gas pressure;

carrying out corrosion treatment on the sample by using the plasma;

a pulse bias is applied to the one electrode while the etching treatment is performed,

and, the above sample uses SiO₂。

29. A plasma processing method is characterized by comprising the following processing program steps:

placing the sample on one of a pair of electrodes mounted in a vacuum processing chamber;

fixing the sample on the electrode by electrostatic adsorption force;

preliminarily plasmatizing a radical generating gas in the ambient gas in which the position of the sample is placed and fixed, and supplying a required number of radicals;

supplying an ion generating gas to the ambient gas at the position;

applying a high-frequency voltage of 30MHz to 100MHz to the ambient gas at the position, and plasmatizing the supplied ion generating gas under the gas pressure;

treating the sample with the plasma;

a pulse voltage is applied to the sample,

and, the above sample uses SiO₂。

30. A plasma processing method is characterized by comprising the following processing program steps:

placing the sample on one of a pair of electrodes in a vacuum processing chamber;

fixing the sample on the electrode by electrostatic adsorption force;

preliminarily plasmatizing a radical generating gas in the ambient gas in which the position of the sample is placed and fixed, and supplying a required number of radicals;

supplying an ion generating gas to the ambient gas at the position;

reducing the ambient air pressure at said location to a pressure required for processing said sample;

plasmatizing the supplied ion generating gas under the gas pressure;

the sample is treated with the plasma as described above,

a pulsed bias voltage is applied to the sample,

the voltage of the electrostatic adsorption device is set to 1/2 or less of the pulse bias.

31. A plasma processing method is characterized by comprising the following processing program steps:

placing the sample on one of a pair of opposing electrodes within a vacuum processing chamber;

fixing the sample on the electrode by using electrostatic adsorption force;

preliminarily plasmatizing a radical generating gas in the ambient gas in which the position of the sample is placed and fixed, and supplying a required number of radicals;

supplying an ion generating gas to the ambient gas at the position;

reducing the ambient gas at said location to 0.5-4.0 Pa;

applying a high-frequency voltage of 30MHz to 100MHz between the pair of opposing electrodes, and plasmatizing the supplied ion generating gas under the gas pressure;

treating the sample with the plasma;

a pulsed bias is applied to the sample.

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