JPH08264515A - Plasma processing apparatus, processing apparatus, and etching processing apparatus - Google Patents

Abstract

(57) [Abstract] [Purpose] Diffusion of plasma generated between opposed electrodes is prevented, its density is increased, and high fine processing of an object to be processed is enabled. [Structure] High frequency from a high frequency power source 51 is applied to the upper electrode 21.
The high frequency of the high frequency power source 52 is applied to the susceptor 5. A substantially cylindrical ground electrode 27 is provided near the periphery of the upper electrode 21 so as to surround the inter-electrode space. The phase controller 57 controls each high frequency power source to apply high frequencies having different current phases of 180 ° to the upper electrode 21 and the susceptor 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus, a processing apparatus and an etching processing apparatus.

[0002]

2. Description of the Related Art For example, regarding a plasma processing apparatus, it has been widely used to perform a surface treatment of a semiconductor wafer (hereinafter referred to as a "wafer") in a semiconductor manufacturing process. A so-called parallel plate type plasma processing apparatus has many advantages because it has advantages such as excellent uniformity and capable of processing a large-diameter wafer, and the apparatus configuration is relatively simple.

In the conventional general parallel plate type plasma processing apparatus, electrodes are provided parallel to each other in the upper and lower parts of a processing chamber, and a wafer to be processed is mounted on, for example, a lower electrode. For example, in the case of etching treatment, while introducing an etching gas into this treatment chamber, applying high frequency power to the electrodes to generate plasma between the electrodes, and by etchant ions generated by dissociation of the etching gas, It is configured to etch the wafer. In such a case, the etching gas is directly discharged toward the wafer from a large number of holes of a gas diffusion plate forming a discharge portion provided on the surface of the upper electrode facing the wafer.

By the way, the processing by plasma processing is
As semiconductor devices become highly integrated, finer processing, higher processing speed, and more uniform processing are required.
Therefore, it is necessary to increase the density of the plasma generated between the electrodes. Furthermore, the silicon oxide film (S
When forming a contact hole in iO ₂ ), extremely high selectivity is required.

With respect to the above points, for example, JP-A-57-15
No. 9026 “Dry etching method” discloses a magnetron type plasma processing apparatus using a magnetron as a new plasma generating method, and Japanese Patent Publication No. 58-12346 “Plasma etching apparatus” discloses a conventional electrode. Besides, a configuration in which a common anode electrode having a grid shape or the like is adopted between the upper and lower electrodes is disclosed. In the conventional electrode of this type, the lower electrode is generally made of aluminum, while the upper electrode is made of carbon.

[0006]

However, in the above-mentioned magnetron type plasma processing apparatus, it is possible to obtain a high density plasma in a relatively high vacuum, but the change of the magnetic field is much slower than the frequency of the high frequency electric field. Therefore, the plasma state changes in accordance with the change in the magnetic field, and this change gives rise to changes in the ion energy and directionality, which may cause element damage or deterioration of the processed shape.
Also, the common anode configuration has the advantage that the ion energy and current density can be controlled independently, but the plasma diffuses through the grid, the ion current density incident on the wafer becomes low, and the processing rate decreases. There is a risk that the process may be lost or the treatment may not be uniform. When high-frequency, high-vacuum atmosphere is created with high fine processing, the impedance between the electrode and the inner wall of the processing container is lowered, and the environment in which plasma is more likely to diffuse becomes.

When the plasma diffuses in the processing chamber as described above, not only the plasma density is lowered, but also metal contamination occurs on the inner wall of the processing chamber to contaminate the wafer to be processed. I will end up. Such a tendency becomes more remarkable in the plasma processing under the high decompression degree required for high fine processing which will be required more and more in the future.

In the above-mentioned conventional gas diffusion plate, when there is, for example, a quartz shield ring or other member around the gas diffusion plate, it hinders the improvement of the etching rate, and the concentration distribution of the processing gas varies. There is a risk of delicate effects and impeding the uniformity of the etching process.

By the way, when, for example, CHF ₃ is used as the etching treatment gas, C is directly generated by plasma.
Fluorine radicals (F ^* ) excessively generated due to the progress of dissociation of HF ₃ may cause etching up to the base of silicon and reduce the selection ratio. Therefore, conventionally, CO was added to the processing gas, whereby A carbon-rich depot (a kind of protective film) is formed on the surface of the underlayer to prevent the fluorine radical from excessively etching the underlayer of silicon, thereby increasing the selection ratio of the oxide film to the underlayer. I had no choice but to do it.

The present invention has been made in view of the above point, and in order to satisfactorily carry out high-fine plasma processing as described above, the first purpose thereof is a relatively simple parallel plate type. While adopting the above apparatus configuration, plasma is not diffused in the processing chamber, is confined in the inter-electrode space to achieve a high plasma density, and contamination is not generated on the inner wall of the processing chamber. A second object of the present invention is to uniformize the plasma density in the processing space and prevent unevenness in processing. A third object of the present invention is to maintain a stable plasma even at a high pressure reduction degree. A fourth object of the present invention is to provide an etching processing apparatus capable of improving a selection ratio by forming a carbon-rich depot on, for example, a silicon base surface without adding CO to a processing gas in the etching processing. To provide a solution to the above problems.

[0011]

In order to achieve the above object, according to claim 1, a plasma is generated by a high frequency power between a first electrode and a second electrode provided opposite to each other in a processing chamber. In the plasma processing apparatus configured to process the object to be processed in the processing chamber under the plasma atmosphere, the plasma is generated in the space between the electrodes in the vicinity of the space between the electrodes in the processing chamber. A plasma processing apparatus is provided, which is provided with a plasma confinement means for confining.

In this case, the plasma confinement means itself may be an insulator surrounding the space between the electrodes, or may be an insulator having a plurality of through holes. The confinement means may be a grounded third electrode. The third electrode has a substantially annular shape surrounding the inter-electrode space, and the inner circumference thereof may be convexly curved toward the inter-electrode space. Of course, a plurality of through holes are formed. May be.

According to the second aspect of the present invention, plasma is generated by the high frequency power between the first electrode and the second electrode, which are provided to face each other in the processing chamber, and the plasma is generated with respect to the object to be processed in the processing chamber. In the plasma processing apparatus configured to perform the processing under the plasma atmosphere, a substantially annular third electrode is provided in the vicinity of the outer periphery of the first electrode, and the third electrode is provided in the vicinity of the outer periphery of the second electrode. Is provided with a substantially annular fourth electrode,
A plasma processing apparatus is provided, in which the third electrode and the fourth electrode are grounded.

In this case, the third electrode arranged in the vicinity of the first electrode and the fourth electrode arranged in the vicinity of the second electrode are opposed to each other, and their outer peripheral edge portions are overlapped with each other. It is more preferable to arrange them so that the outer peripheral edge portions of the two electrodes facing each other when viewed from the plane are aligned with each other.

According to the third aspect of the present invention, plasma is generated by the high frequency power and the object to be processed in the processing chamber is
In a plasma processing apparatus configured to perform processing in the plasma atmosphere, the first,
A plurality of magnets are arranged in a substantially annular shape in the vicinity of the periphery of each of the second electrodes, and the magnets arranged on the first electrode side and the magnets arranged on the second electrode side are opposed to each other and face each other. Characterized in that the magnetic poles of the respective magnets are different from each other,
A plasma processing apparatus is provided.

A plasma processing apparatus according to a fourth aspect of the present invention relates to the arrangement of the magnets in the plasma processing apparatus according to the third aspect, wherein the magnet is disposed on the first electrode side and the magnet is disposed on the second electrode side. It is characterized in that not only the side facing the magnet but also the magnetic poles between the adjacent magnets are different from each other.

When the magnets are arranged in a substantially annular shape, the magnetic field strength at the peripheral portion of the object to be processed generated by the magnets is 1
It is preferably 0 Gauss or less. Further, in each plasma processing apparatus configured as described above, high frequency power for generating plasma may be applied to the first electrode and the second electrode, respectively.

According to a fifth aspect of the present invention, plasma is generated by high-frequency power between the first electrode and the second electrode that are provided facing each other in the processing chamber, and the plasma is generated on the object to be processed in the processing chamber. On the other hand, in the plasma processing apparatus configured to perform the processing under the plasma atmosphere, the frequencies of the respective high frequency powers applied to the first electrode and the second electrode are the same, and the two high frequency powers Current phase difference,
A plasma processing apparatus is provided, which is provided with means for controlling to approximately 180 °.

In this case, the means for controlling the current phase difference to approximately 180 ° are, as described in claim 15, a detecting means for detecting the phase of the high frequency current flowing through each electrode and outputting a phase signal, and these detecting means. And a means for detecting and outputting the phase difference from the phase signal. And the detection means for detecting the phase of the high frequency current and outputting the phase signal is
It may be a current transformer, and the means for detecting and outputting the phase difference from the phase signal may be configured based on the heterodyne system.

Further, in each plasma processing apparatus,
The processing container having the processing chamber formed therein is grounded, and the first and second electrodes are insulated from the processing container.
High-frequency power from two high-frequency power sources is configured to be switchably applied to either the first electrode or the second electrode,
Further, the first and second electrodes may be configured to be freely grounded. In this case, either one of the first electrode and the second electrode is used as the high frequency power application side electrode by the switching. At this time, the other electrodes may be grounded at the same time.

In each of the above plasma processing apparatuses,
The output of the high frequency power may be periodically modulated, and the output modulation width in such a case is such that the output at the minimum is in the range of 1/2 to 1/5 of the output at the maximum. It is possible to obtain a more preferable result by setting.

According to a sixth aspect of the present invention, there is an upper electrode and a lower electrode which face each other vertically in a depressurizable processing chamber, and plasma is generated between the upper and lower electrodes so that the object on the lower electrode is processed. In the plasma processing apparatus configured to perform processing under the plasma atmosphere, relative high frequency power is applied to the upper electrode, relative low frequency power is applied to the lower electrode, and There is provided a plasma processing apparatus, characterized in that a gap (gap) length between an upper electrode and a lower electrode is set to 10 to 40 mm.

Also, in the plasma processing apparatus according to the above-mentioned claims 1, 2, 3, and 4, the first electrode is the upper electrode,
The second electrode constitutes a lower electrode, a relative high frequency power is applied to the upper electrode, a relative low frequency power is applied to the lower electrode, and a space between the upper electrode and the lower electrode is further applied. The interval (gap) length may be set to 10 to 40 mm.

In the sixth aspect, the relative high frequency power refers to power having a frequency of 10 to 40 MHz, and the relative low frequency power refers to power having a frequency of 300 kHz to 3 MHz. Further, the interval (gap) length in the plasma processing apparatus according to claim 6 may be set to 15 to 30 mm, and according to the knowledge of the inventors, particularly preferable setting is about 25 mm to obtain a more preferable result. .

When applied to both upper and lower sides,
It is preferable to configure the upper electrode so that it is applied before the lower electrode, or to stop the power application, if the lower electrode is configured so that it is stopped before the upper electrode. can get.

By the way, in this type of plasma processing apparatus, a matching means such as a matching device or a matching device, which is usually called a matching device, is provided. In such a matching means, impedance and phase are independently controlled. By doing so, favorable results are obtained.

In each of the above plasma processing apparatuses, the processing chamber pressure may be freely set to 5 mTorr to 100 mTorr.

According to a seventh aspect, the processing chamber can be decompressed freely,
A processing unit having a discharge unit located above the processing chamber, configured to discharge a processing gas from the discharge unit into the processing chamber and perform a predetermined process on an object to be processed in the processing chamber. In the above, there is provided a processing apparatus, characterized in that a gas diffusion guide that is opened in a tapered shape toward the object to be processed is provided at the peripheral edge of the discharge part.

In this case, it is more preferable to set the taper angle of the gas diffusion guide and the angle formed by the tapered surfaces of the gas diffusion guide in the horizontal direction to 25 to 35 °, and in the peripheral portion of the object to be processed, A gas diffusion exhaust guide having an inverse taper shape to the gas diffusion guide may be provided. The tapered portion of the gas diffusion exhaust guide does not necessarily have to have an angle facing the tapered portion of the gas diffusion guide. That is, the tapered portions do not necessarily have to be parallel to each other.

According to claim 8, a decompression-free processing chamber;
An upper electrode and a lower electrode are provided above and below the processing chamber so as to face each other, and a processing gas is discharged into the processing chamber from a discharge portion provided on the upper electrode side, and plasma is generated between the upper electrode and the lower electrode. In a plasma processing apparatus configured to perform processing on an object to be processed on the lower electrode, a gas diffusion guide that is opened in a taper shape toward the object to be processed is provided at the peripheral edge of the discharge part. A plasma processing apparatus is provided.

Also in this case, it is more preferable to set the taper angle in the gas diffusion guide and the angle formed by the tapered surfaces of the gas diffusion guide in the horizontal direction to 25 to 35 °, and in the peripheral portion of the object to be processed, A gas diffusion exhaust guide having an inverse taper shape to the gas diffusion guide may be provided. The tapered portion of the gas diffusion exhaust guide does not necessarily have to be parallel to the tapered portion of the gas diffusion guide.

A gas diffusion exhaust guide having an inverse taper shape to the gas diffusion guide may be provided on the lower electrode side of the plasma processing apparatus according to claim 8.
Further, the gas diffusion guide is arranged so as to surround the upper electrode, the gas diffusion guide is electrically conductive and is grounded, and a ground electrode facing the gas diffusion guide is provided on the lower electrode side. May be. The gas diffusion guide may be arranged so as to surround the upper electrode, and both the gas diffusion guide and the gas diffusion exhaust guide may be electrically conductive and grounded.

According to the ninth aspect, the upper electrode and the lower electrode are opposed to each other in the processing chamber where the pressure can be freely reduced, and C is provided in the processing chamber.
In the etching processing apparatus configured to introduce a processing gas containing (carbon) and F (fluorine) and generate plasma between these electrodes to perform etching processing on the object to be processed on the lower electrode, There is provided an etching processing apparatus characterized in that at least a part of the upper electrode is made of SiO ₂ .

According to the tenth aspect of the present invention, the upper electrode and the lower electrode are opposed to each other in the depressurizable processing chamber, the processing gas containing C and F is introduced into the processing chamber, and the plasma is generated between these electrodes. In the etching processing apparatus configured to perform the etching process on the object to be processed on the lower electrode, a focus ring is installed around the lower electrode so as to surround the object to be processed, and at least the focus ring There is provided an etching processing apparatus, characterized in that a part thereof is made of a material containing BN (boron nitride).

According to a third aspect of the present invention, the upper electrode and the lower electrode are opposed to each other in a depressurizable processing chamber, a processing gas containing C and F is introduced into the processing chamber, and a plasma is generated between these electrodes. In an etching processing apparatus configured to generate and perform etching processing on the object to be processed on the lower electrode, at least a part of the upper electrode is made of SiO.
_A focus ring is provided around the lower electrode so as to surround the object to be processed, and the focus ring is made of a material containing BN (boron nitride). Provided.

The processing gas used in each of these etching processing apparatuses is, for example, CF ₄ , C ₂ F ₆ , C ₃
It may be a fluorocarbon-based gas typified by F ₈ , C ₄ F ₈ and CHF ₃ .

[0037]

When the plasma confinement means for confining the plasma in the inter-electrode space is provided in the vicinity of the inter-electrode space in the processing chamber as in claim 1, the plasma stays in the inter-electrode space and is surrounded. It does not spread. Therefore, the plasma density in the processing region becomes high, and on the other hand, contamination does not occur on the inner wall of the processing chamber. When the plasma confinement means is an insulator surrounding the inter-electrode space, diffusion of ions in the plasma is directly regulated by this insulator, and when the plasma confinement means is the third electrode grounded. The ions that try to diffuse positively move to the side of the third electrode, and in any case, the diffusion of plasma is eventually prevented.

Considering only the purpose of preventing such plasma diffusion, the shape of the plasma confinement means is preferably, for example, a cylindrical shape capable of enclosing the interelectrode space, but considering the exhaust of the etching gas introduced into the interelectrode space, As described above, by providing a plurality of through holes, it is possible to prevent the diffusion of plasma at the same time without damaging the exhaust.

Further, when the grounded third electrode is provided as described above, since ions are positively attracted so to speak, it has a substantially annular shape surrounding the inter-electrode space,
When the inner circumference is convexly curved toward the inter-electrode space, the surface area exposed to the plasma side becomes large, and it is possible to achieve the intended purpose even for plasma generated by a large power. It is possible.

As described in claim 2, when the ground electrodes having the substantially annular shape are arranged near the first electrode and near the second electrode, respectively, the first electrodes on the opposite side are provided. And ions from each of the second electrodes can be attracted, respectively, thereby preventing plasma diffusion. That is, the third electrode can attract the corresponding ions from the second electrode and the fourth electrode from the first electrode, respectively, thereby preventing plasma diffusion. In this case, if the two electrodes that are grounded, that is, the third electrode and the fourth electrode are arranged so that the outer peripheral edge portions thereof overlap, plasma diffusion can be further prevented.

According to the third aspect, a plurality of magnets are arranged in a substantially annular shape in the vicinity of the periphery of each of the first and second electrodes in the processing chamber, and a magnet arranged on the first electrode side, Since the magnets arranged on the second electrode side are opposed to each other and the magnetic poles of the magnets opposed to each other are different from each other, a local area is formed around the space between the circumferences of the first and second electrodes. A strong magnetic field is formed, which makes it possible to trap charged particles in the plasma and prevent plasma diffusion.

According to a fourth aspect of the present invention, regarding the arrangement of the magnets, not only the magnets arranged on the first electrode side and the magnets arranged on the second electrode side are opposed to each other but also adjacent magnets. Since the magnetic poles are also different from each other, the trapped structure of the charged particles by the magnetic field becomes dense, and the plasma diffusion preventing effect higher than that of the third aspect can be obtained.

The magnetic field strength at the peripheral portion of the object to be processed generated by the magnets arranged as described above is set to 10 Gauss.
When the following settings are made, the desired plasma processing can be performed without affecting the plasma in the plasma processing region of the object to be processed such as a wafer.

If the high frequency power is applied to each of the first electrode and the second electrode in each of the plasma processing apparatuses configured as described above, the voltage of each high frequency power is independently variable. Is easy to do.

According to the fifth aspect, the current phase difference between the high frequency powers applied to the first electrode and the second electrode is about 180.
The high frequency power can be efficiently supplied to the plasma regardless of the degree of pressure reduction in the processing chamber and the type of processing gas introduced into the processing chamber. Therefore, the plasma density near the object to be processed increases, and the current density of the ions incident on the object to be processed increases.

In this case, as described above, the means for controlling the current phase difference to approximately 180 ° detects the phase of the high frequency current flowing through each electrode and outputs the phase signal, and from these phase signals. Such control can be performed smoothly by adopting a configuration including means for detecting and outputting the phase difference. If the detecting means for detecting the phase of the high frequency current and outputting the phase signal is a current transformer, the device configuration is simplified. In this case, from the viewpoint of suppressing the influence of the phase shift in the transmission line or the matching device and performing accurate detection, it is preferable to arrange the current transformer as close to the electrode as possible.

By the way, as described above, the processing container having the processing chamber formed therein is grounded, and the first and second electrodes are insulated from the processing container, so that high-frequency power from one high-frequency power source is supplied. The first electrode or the second electrode is configured to be switchably applied to either the first electrode or the second electrode.
If the second electrode is configured to be freely grounded, the mode in which the second electrode is grounded while the voltage is applied to the first electrode, and vice versa, the first electrode is grounded and the second electrode is Two plasma processing modes are obtained, a mode for applying electric power. Therefore, two different plasma processing modes can be obtained in one processing chamber. For example, when the object to be processed is placed on the first electrode and the object to be processed is etched, the former mode is used. In the latter mode, it is possible to perform an etching treatment with a large DC bias, and in the latter mode, an etching treatment with a small DC bias can be performed. Therefore, it is possible to continuously perform different processes in the same processing chamber and to expand the application of the process.

In this case, when the electrode on the high frequency power application side is switched, the other electrode is switched and grounded at the same time, so that the switching between the two modes can be performed by switching one relay system, for example.

Further, in each of the above plasma processing apparatuses, if the high frequency power output is periodically modulated,
It is possible to repeat high and low plasma densities, and to control dissociation of gas components in plasma.For example, in contact hole etching treatment, etching proceeds at high output, while at low output, the inside of the hole is advanced. It is possible to adopt a process of discharging the etching reaction product of. Therefore, it is possible to perform etching with excellent vertical anisotropy while increasing the etching rate and suppressing the difference in size between the hole bottom and the hole entrance. In such output modulation, if the output at the minimum is set to be in the range of 1/2 to 1/5 of the output at the maximum, it is possible to maintain the plasma state and to discharge the etching reaction products as such. It can be in a preferable state.

According to a sixth aspect of the present invention, the gap length between the upper electrode and the lower electrode is set to 10 to 40 mm, and relative high frequency power and relative low frequency power are applied to the vertically opposed electrodes, respectively. When the plasma is generated, it is possible to perform a well-balanced process with respect to the etching rate, the uniformity, and the stability of the plasma, as will be described in detail in Examples below. In addition, the gap length is 15 to 30 m
Even better results are obtained by setting m, especially around 25 mm.

In the case of applying to both the upper electrode and the lower electrode, the upper electrode is applied first, and the lower electrode is applied later than that to generate the plasma. An excessive voltage is not applied to the object to be processed placed on the electrode, plasma is easily generated, and there is little risk of damaging the object to be processed. Also, when the plasma is extinguished, if the applied power on the lower electrode side is stopped first, and then the applied power on the upper electrode side is stopped with a delay, the deposition does not proceed and damage to the target object is prevented. It becomes possible to do. In short, if such an application and stop sequence is adopted, the state in which the voltage is applied only to the lower electrode on which the object to be processed is placed is avoided.
The object to be processed is protected from excessive voltage. If the timing of delaying is set to, for example, 1 second or less, the desired effect can be obtained.

As described above, if the matching means is configured to control the impedance and the phase independently,
It is less susceptible to disturbances and more easily matched to load fluctuations.

Then, the processing chamber pressure is set to 5 mTorr-100
Highly fine processing can be performed under a high degree of vacuum by configuring mTorr freely.

According to the processing apparatus of the seventh aspect, the gas diffusion guide opened in a taper shape toward the object to be processed,
Since it is provided at the periphery of the discharge part for discharging the processing gas into the processing chamber, the gas flow conductance is reduced, and the processing gas is discharged toward the object to be processed more favorably. Therefore,
Accordingly, the object can be processed under a more preferable atmosphere of the processing gas. If the taper angle in this gas diffusion guide is set to 25 to 35 °, a more preferable result can be obtained. Further, when a gas diffusion exhaust guide is further provided, the gas diffusion guide is combined with the gas diffusion guide to further improve the gas level. Distribution is smooth and favorable processing results are obtained.

According to the plasma processing apparatus of the eighth aspect, the action of the seventh aspect can be obtained when the object to be processed is processed in a plasma atmosphere. If the gas diffusion guide constitutes a ground electrode, and a ground electrode facing the gas diffusion guide is provided on the lower electrode side, plasma generated between the electrodes is confined between the ground electrodes. As a result, the plasma density is improved. Further, if the gas diffusion guide is arranged so as to surround the upper electrode, and both the gas diffusion guide and the gas diffusion exhaust guide are electrically conductive and grounded, the gas diffusion on the lower electrode side Since the exhaust guide constitutes the ground electrode, not only is the plasma confined,
The flow of processing gas becomes smoother.

In the etching treatment apparatus of the ninth aspect, since at least a part of the upper electrode is made of SiO ₂ , when a treatment gas containing C and F is introduced and dissociated by plasma, SiO ₂ A reaction such as + Cx · Fy → XSiF ₄ + YCO ₃ occurs, and the same result is obtained as when CO is added to the processing chamber. Therefore, for example, it becomes possible to form a carbon-rich deposit on the surface of the silicon underlayer, and the selectivity with respect to the silicon underlayer is improved.

By the way, the focus ring itself in claim 10 is known and has a function of efficiently injecting ions such as radical components into the object to be processed.
In the tenth aspect, at least a part of the focus ring is made of a material containing BN (boron nitride). Therefore, when a processing gas containing C and F is introduced and dissociated by plasma, excess fluorine radicals (F ^* ) are combined with B and become 2BN + 6F → 2BF ₃ ↑ + N ₂ ↑, which is exhausted. Fluorine radicals that excessively etch the silicon underlayer are reduced, and as a result, the selectivity to the underlayer is improved.

According to the eleventh aspect, since the two actions of the ninth and tenth aspects are performed, the selection ratio is further improved. In addition, as processing gas, CF ₄ , C ₂ F ₆ , C
With the _{3 F 8, C 4 F 8} , CHF 3 fluorocarbon gas typified by such essentially claim 9-1
The same effect as in the case of 1 can be obtained, excessive etching due to fluorine radicals can be prevented, and etching treatment with a high selection ratio can be performed. Then, by setting the pressure in the processing chamber to 5 mTorr to 100 mTorr, it becomes possible to perform high-precision processing under a high degree of vacuum.

[0059]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 schematically shows a cross section of an etching processing apparatus 1 of the first embodiment.
Is configured as a so-called parallel plate type etching device in which the electrode plates face each other in parallel.

The etching processing apparatus 1 has a processing container 2 which is formed into a cylindrical shape and is made of, for example, aluminum whose surface is anodized, and which is grounded. At the bottom of the processing chamber formed in the processing container 2, a substantially cylindrical column for mounting an object to be processed, for example, a semiconductor wafer (hereinafter referred to as “wafer”) W via an insulating plate 3 made of ceramic or the like. The susceptor support base 4 is housed therein, and the susceptor 5 forming a lower electrode is provided on the susceptor support base 4.

A coolant chamber 6 is provided inside the susceptor support 4, and a coolant for temperature control such as perfluoropolyether can be introduced into the coolant chamber 6 through a coolant introduction pipe 7. The introduced cooling medium circulates in the cooling medium chamber 6, and the cold heat generated during the cooling medium is transferred from the cooling medium chamber 6 to the wafer W via the susceptor 5, so that the processing surface of the wafer W is desired. It is possible to cool to temperature.

The center of the upper surface of the susceptor 5 is formed in a convex disk shape, and an electrostatic chuck 11 having substantially the same shape as the wafer W is provided thereon. This electrostatic chuck 11
Has a structure in which the conductive layer 12 is sandwiched between two polymer polyimide films, and the conductive layer 12 is supplied from the DC high-voltage power supply 13 installed outside the processing container 2 to, for example, 1 By applying a DC high voltage of 0.5 kV, the wafer W placed on the upper surface of the electrostatic chuck 11 is attracted and held at that position by the Coulomb force.

An annular focus ring 15 is arranged around the upper edge of the susceptor 5 so as to surround the wafer W placed on the electrostatic chuck 11. The focus ring 15 is made of an insulating material that does not attract reactive ions, and is configured so that the reactive ions generated by the plasma are effectively incident only on the wafer W inside thereof.

The upper electrode 21 of the processing container 2 is disposed above the susceptor 5 so as to face the susceptor 5 in parallel and to be spaced apart from the susceptor 5 by about 15 to 20 mm, with the insulating material 22 interposed therebetween. It is supported at the top. The upper electrode 21 has a large number of diffusion holes 2 on the surface facing the susceptor 5.
3, an electrode plate 24 made of, for example, SiC or amorphous carbon, and an electrode support 25 made of a conductive material that supports the electrode plate 24, for example, aluminum whose surface is anodized.

A ground electrode 27, which serves as a third electrode as shown in FIG. 2, is provided on the outer periphery of the electrode support 25 via an annular insulating material 26. As shown in FIG. 1, the lower end of the ground electrode 27 is installed with a gap between the lower end of the ground electrode 27 and the upper end of the focus ring 15 so that the wafer W can pass therethrough. As shown in FIG. 1 and FIG. 2, it has a form protruding inward.
The ground electrode 27 is used for the susceptor 5 and the electrode plate 2.
4 is arranged so as to surround the space area between the side and the side.

A gas introduction port 28 is provided at the center of the support plate 25 of the upper electrode 21, and a gas introduction pipe 29 is connected to the gas introduction port 28. A gas supply pipe 30 is connected to the gas introduction pipe 29,
Further, the gas supply pipe 30 is branched into three and communicates with the corresponding process gas supply sources 37, 38 and 39 via valves 31, 32 and 33 and mass flow controllers 34, 35 and 36, respectively. . In this embodiment, the processing gas supply source 37 supplies CF ₄ gas, the processing gas supply source 38 supplies Cl gas, and the processing gas supply source 39 supplies N ₂ gas which is an inert purge gas. Has been done.

An exhaust pipe 41 is connected to the lower portion of the processing container 2, and an exhaust pipe 44 of a load lock chamber 43 adjacent to the processing container 2 via a gate valve 42, a turbo molecular pump, and the like. It communicates with the vacuum evacuation means 45, and is configured to be capable of evacuation to a predetermined reduced pressure atmosphere. The wafer W, which is the object to be processed, is configured to be transferred between the processing container 2 and the load lock chamber 43 by the transfer means 46 such as a transfer arm provided in the load lock chamber 43. ing.

The high frequency power for generating plasma in the processing container 2 of the etching processing apparatus 1 is supplied by two high frequency power supplies 51 and 52 which oscillate a high frequency of 13.56 MHz, for example. That is, high frequency power source 5
1 is configured to apply high frequency power to the upper electrode 21 via the matching unit 53, and the high frequency power supply 52 is configured to apply high frequency power to the susceptor 5 via the matching unit 54. There is. In addition, the upper electrode 21,
Since high frequency power is applied to the susceptor 5 by independent high frequency power sources, the voltages applied to the upper electrode 21 and the susceptor 5 are independently variable.

Further, between the matching unit 53 and the upper electrode 21, and between the matching unit 54 and the susceptor 5, phase detecting means 55, 56 for detecting the phase signal of the current of the high frequency power applied respectively. Are provided respectively. The phase signals detected by the phase detecting means 55 and 56 are input to the phase controller 57, and the phase controller 57 supplies the high frequency power sources 51 and 52 described above based on the detected phase signals. On the other hand, they are so controlled as to oscillate high frequencies whose phases are different by 180 °.

The etching processing apparatus 1 according to this embodiment is configured as described above. For example, the etching processing apparatus 1 is used to etch a silicon oxide film (SiO ₂ ) on a wafer W having a silicon substrate. The case of carrying out
After the gate valve 42 is opened, the carrier is carried into the processing container 2 from the load lock chamber 43 by the carrying means 46 and placed on the electrostatic chuck 11. Then, the wafer W is attracted and held on the electrostatic chuck 11 by the application of the high-voltage DC power supply 13. After that, the transport means 46 retracts into the load lock chamber 43, and then the inside of the processing container 2 is evacuated by the exhaust means 45.

On the other hand, while the valve 31 is opened and the flow rate thereof is adjusted by the mass flow controller 34, the CF ₄ gas from the processing gas supply source 37 is supplied to the gas supply pipe 30,
Upper electrode 21 through gas inlet pipe 29 and gas inlet 28
And is uniformly discharged onto the wafer W through the diffusion holes 23 of the electrode plate 24, as indicated by the arrow in FIG.

The pressure inside the processing container 2 is, for example, 1 Pa.
After being set and maintained at a high frequency, the high frequency power sources 51 and 52 are activated, and high frequency powers having current phases different from each other by 180 ° are applied to the upper electrode 21 and the susceptor 5, respectively. Plasma is generated between
The wafer W is subjected to a predetermined etching by the radical component generated by dissociating the CF ₄ gas introduced into the processing container 2.

The plasma in the etching process is generated between the upper electrode 21 and the susceptor 5 as described above, but as described above, the ground electrode 27 forms the space region between the upper electrode 21 and the susceptor 5. Are arranged so as to surround from the side portion, so that the ions that try to diffuse from the space area are attracted by the ground electrode and do not diffuse to the outside of the space area, for example, the inner wall of the processing container 2. Therefore, the plasma density in the space area, that is, the processing area for the wafer W can be maintained high, which enables highly fine processing of the wafer W.

Moreover, since the diffusion of the ions to the inner wall of the processing container 2 is suppressed, during the processing, the processing container 2
The inner wall is not etched and the reaction product is attached, so that the inner wall is not contaminated and the inside of the processing container 2 is not contaminated. Therefore, the yield does not decrease from this point.

The high-frequency power applied to the upper electrode 21 and the susceptor 5 to generate plasma is
Since the current phases are different by 180 °, high-frequency power can be applied to the plasma regardless of the type of processing gas and the degree of pressure reduction, and the ion current density incident on the wafer W can be increased.

That is, when the phase difference of the frequency of the high frequency power applied between the electrodes facing each other is changed, the state of plasma changes (for example, Japanese Patent Laid-Open No. 2-224239). For example, when the voltage phases of the two high frequency powers are almost the same, the plasma spreads, the density becomes low, and the processing speed decreases. On the other hand, when the voltage phase difference is shifted by 180 °, the plasma density becomes high. However, when the frequencies are 380 kHz and 13.56 MHz, for example, the voltage phase difference at which the plasma density is highest is different. It is considered that this is because the impedance of plasma changes. Similarly, when the composition of the processing gas is changed, the impedance of the plasma also changes due to the difference in the ionization cross-sectional area of the gas or the difference in the dissociation characteristics, and the optimum voltage phase difference also changes. Therefore, in the conventional method of controlling the voltage phase and applying the high frequency power, there is a voltage relationship in which the current flowing from one electrode due to the change in the plasma impedance flows into the counter electrode due to the phase difference. If it is not present, it is difficult to realize the state with the highest plasma density, because it diffuses to the inside wall of the processing container other than the counter electrode.

In this respect, by controlling the current phases to be different by 180 ° as described above, one electrode, for example, the upper electrode 21 is changed from the upper electrode 21 to the susceptor 5 which is the other counter electrode, regardless of the change in the plasma impedance. When attempting to flow in, the phase of the susceptor 5 has a relationship that allows the current to flow, so the current flows efficiently, and as a result, the plasma is confined between the upper electrode 21 and the susceptor 5 and its density is high. It will be.

Moreover, in the present embodiment, as described above, the plasma can be confined by the ground electrode 27 as well, so that they can work together to realize extremely high plasma density, and high fine processing is possible. I am trying.

The ground electrode 27 used in the above embodiment is used.
Had a form in which it was formed to be convex inside, but instead of this, as shown in FIG. 3, for example, a simple cylindrical ground electrode 61 was used, and this was supported via an insulating material 62 as an electrode support. It is also possible to arrange it on the outer periphery of the body 25 and to fix the grounded processing container 2 and the ground electrode 61 to each other.

Further, in order to make the space between the opposed electrodes more closed, the height of the ground electrode may be further increased to form a cylindrical shape. In such a case, a plurality of through holes 64 are formed around the ground electrode 63 as shown in FIG. 4 in order to ensure sufficient exhaust of the processing gas introduced into the space between the counter electrodes. Preferably.

Further, as another example of the ground electrode which confines the plasma between the opposed electrodes and does not diffuse it to the surroundings, the ground electrodes 65 and 66 as shown in FIG. 5 may be used.
As can be seen from the figure, the ground electrodes 65 and 66 each have a substantially ring shape, the ground electrode 65 is arranged on the outer circumference of the upper electrode 21, and the ground electrode 66 is arranged on the outer circumference in the vicinity of the upper end of the susceptor 5. It is arranged (in this case, the so-called upper part of the exhaust ring may be provided). As a result, the charged particles that try to diffuse from the upper electrode 21 are attracted to the ground electrode 66, and the charged particles that try to diffuse from the susceptor 5 are attracted to the ground electrode 65. As a result, the upper electrode 21 and the susceptor 5 are attracted. The plasma generated during this period does not diffuse to the inner wall of the processing container 2.

The ground electrodes 67 and 68 shown in FIG.
Instead of the shape of the electrode, the electrode has a ring shape and the cross section is formed into a substantially triangular shape so as to form an inclined surface. According to the ground electrodes 67 and 68 having such a configuration, for example, the upper ground electrode 67 has an inner sloped surface facing the direction of the susceptor 5, so that it is more effective than the ground electrode 65 shown in FIG. You can efficiently attract charged particles,
Further, the plasma diffusion preventing effect is improved.

The ground electrode shown in FIGS. 5 and 6 is
Both of them have a vertically opposed structure, but the plasma diffusion preventing effect can be obtained without necessarily having such a structure.

In the above-mentioned example, as the means for preventing the plasma diffusion, the upper electrode 21 and the third electrode other than the susceptor 5 are provided, but instead of this, for example, FIG.
As shown in, the magnets may be arranged to face each other around the vicinity of the upper electrode 21 and the susceptor 5. That is, the upper electrode 21 has an annular insulating member 7 on the outer periphery of the lower end of the electrode support 25.
1 is provided, and substantially cylindrical permanent magnets 72 shown in FIG. 8 are provided inside the insulating member 71 in an annular shape at equal intervals. In this embodiment, as shown in FIG. 7, the lower surface side, that is, the susceptor 5
When the N poles of all the permanent magnets 72 are located on the side and are arranged in a ring shape, as shown in FIG. 9, the central angle θ formed by another adjacent permanent magnet is 10 degrees.
It is set so that it becomes ゜.

On the other hand, as shown in FIG. 7, an annular insulating member 73 is also provided on the outer circumference of the upper end portion of the susceptor 5, and the insulating member 73 has the same shape, the same size, and the same magnetic force as the permanent magnet 72. The permanent magnets 74 are arranged in the same number and at the same intervals so as to face the permanent magnets 72. The magnetic poles of the permanent magnets 74 arranged on the susceptor 5 side are different from the magnetic poles of the facing portion of the permanent magnet 72, that is, the S poles are located on the upper electrode 21 side. Therefore, the relationship between the magnetic poles of the permanent magnets 72 and 74 is
It is as shown in FIG.

By arranging the magnets in this way, a local magnetic field is generated between the peripheral portion of the upper electrode 21 and the peripheral portion of the susceptor 5, and the magnetic field causes charging in the space between the upper electrode 5 and the susceptor 5. Particles can be trapped from jumping outside, and the plasma can be confined in the inter-electrode space. If the strength of the magnetic field is too large, the plasma itself may be biased and may affect the plasma processing itself. Therefore, the magnetic field strength in the peripheral portion of the wafer W, which is the object to be processed, should be 10 Gauss or less. It is desirable to set.

In order to make the above-mentioned local magnetic field form more preferable, as shown in FIG.
For example, a magnetic body 75 may be provided on the upper end of the permanent magnet 72 to be used together with the permanent magnet 72.

Further, in the example shown in FIGS. 7 and 10, the permanent magnet 72 arranged on the upper electrode 21 side and the permanent magnet 74 arranged on the susceptor 5 side are different from each other in the vertical direction. Although the magnetic poles have the same magnetic poles, the adjacent magnets have the same magnetic poles. Instead, as shown in FIG. 12, the adjacent magnets are arranged so that the magnetic poles are different from each other. If so, a further preferable effect can be obtained. That is, by arranging as shown in FIG. 12, magnetic flux is generated not only in the vertically opposed portions but also in the adjacent opposed portions,
This makes the trap system for charged particles more dense.
Therefore, the plasma confinement action is further improved as compared with the case of FIG.

By the way, as described above, finer processing is now required in the manufacturing process of semiconductor devices as they are highly integrated. For example, even when a contact hole is formed by etching, fine processing is required so that the hole diameter is 0.3 μm and the hole depth is 1 to 2 μm. However, in the conventional parallel plate type plasma device, since the high frequency power of a constant output is always applied, when the hole diameter becomes small like this, as shown in FIG.
It becomes difficult for the etching reaction product Z to be discharged, and the etching reaction product Z is deposited on the bottom of the hole 81 and in the vicinity of the bottom, and the replacement with the etching gas cannot be performed smoothly. As a result, as shown in FIG. 13, the shape of the hole 81 is reversed. There has been a problem that the shape of the cone is truncated or the etching rate is lowered, so that fine processing corresponding to high integration cannot be performed.

In order to deal with such a problem, for example, by controlling the outputs of the high frequency power supplies 51 and 52 in the plasma processing apparatus 1, as shown in the graph of FIG. 14, for example,
The output may be applied to the upper electrode 21 and the susceptor 5 by repeating the magnitude of the output every 10 ms. In FIG. 14, the maximum output is controlled to 1000 w, and the minimum output is controlled to ⅕ that of 200 w. By controlling in this manner, the plasma density is increased when the power is high to advance the etching, and the plasma density is decreased when the power is low to discharge the etching reaction products generated in the holes 82 shown in FIG. It is possible to facilitate the replacement of the etching gas with the etching gas, and to form a hole having the same diameter at the inlet and the bottom as shown in FIG. The maximum and minimum of the power and the cycle thereof may be appropriately selected according to the size of the target hole, the material, the type of processing gas, and the like.

The above-mentioned etching processing apparatus 1 uses two high frequency power supplies for generating plasma, and uses the upper electrode 21.
And a high frequency is applied to the susceptor 5, but if one of the electrodes is always grounded by switching and only the other electrode is applied, it is possible to use one device. The configuration makes it possible to carry out two different modes of etching.

It is also possible to perform such switching using one high frequency power source. The example shown in FIG. 16 is an etching processing apparatus 9 capable of performing such two different modes of etching processing using one high frequency power supply 91.
2 is shown, and an upper electrode 94 and a lower electrode 95 are vertically opposed to each other in a grounded processing container 93 that can be decompressed. And on the upper part of this processing container 93,
The first vacuum relay 96 is housed in the shield box 97, and is responsible for switching connection between the upper electrode 94 and the high frequency power supply 91 or the processing container 93. Also, a second vacuum relay 99 is housed in the matching box 98, the lower electrode 95 is switched to the high frequency power source 91 or the ground side, and the path of the high frequency power source 91 leading to the first vacuum relay 96 is turned on. It is responsible for switching off.

Etching processing apparatus 9 having such a configuration
According to 2, R in which the DC bias is large in the state of FIG.
In the IE (Reactive Ion Etching) mode, the upper electrode 94 is grounded, and the high frequency power from the high frequency power supply 91 is applied to the lower electrode 95 to the object to be processed such as a wafer existing between the electrodes. It is possible to carry out fine processing in a high vacuum region and etching treatment with a high controllability in a vertical shape.

When the first vacuum relay 96 and the second vacuum relay 99 are switched to the PE (plasma etching) mode having a small DC bias shown in FIG. 17, the lower electrode 95 is grounded and the upper electrode 94 is supplied with a high frequency power source. By applying high-frequency power from 91, it is possible to carry out an etching process with high dimensional control with little damage to the object to be processed such as a wafer existing between the electrodes. Therefore, the first
By simply switching between the vacuum relay 96 and the second vacuum relay 99, it is possible to successively perform two different etching processes on the same target object in the same processing chamber, expanding the application of the process. Can be achieved.

Explaining still another embodiment, FIG. 18 schematically shows a cross section of an etching processing apparatus 101 of a second embodiment having a structure for applying high frequency power having different frequencies to the upper and lower opposing electrodes. A processing chamber 102 in this etching processing apparatus 101 is formed in a processing container 103 formed into a cylindrical shape made of aluminum which has been airtightly closed and which can be oxidized and anodized, and the processing container 103 itself is grounded. . At the bottom of the processing chamber 102 formed in the processing container 103, an object to be processed, for example, a semiconductor wafer (hereinafter, referred to as “wafer”) W is mounted via an insulating plate 104 such as ceramics. A columnar susceptor support 105 is housed, and a susceptor 106 that constitutes a lower electrode is provided on the susceptor support 105.

A refrigerant chamber 107 is provided inside the susceptor support 105, and the refrigerant chamber 107 includes:
Similar to the etching processing apparatus 1 described above, a coolant for temperature control can be introduced through the coolant introduction pipe, and the introduced coolant circulates in this coolant chamber 107, and the cold heat generated during that time is from the coolant chamber 107 Heat is transferred to the wafer W via the susceptor 106, and the processing surface of the wafer W can be cooled to a desired temperature. Further, a heating means 108 such as a ceramic heater is provided between the susceptor 106 and the refrigerant chamber 107, and by the cold heat of the refrigerant chamber 107 and the heating means 108,
The wafer W can be set and maintained at a predetermined temperature.

Further, the susceptor 106 is provided with an electrostatic chuck 111, and by applying a high DC voltage from a high DC power source 112 installed outside the processing container 103, the wafer W is placed on the upper surface of the electrostatic chuck 111. Adsorbed and held. An annular focus ring 113 is arranged on the upper edge of the susceptor 106 with an insulating material 113 interposed therebetween.
Further, an annular ground electrode 115 is provided.

Above the susceptor 106, the upper electrode 121 is opposed to the susceptor 106 in parallel with the gap length of about 25 mm, and the upper electrode 121 is interposed via the insulating support material 122.
It is supported on the upper part of 03. This upper electrode 121 is
Similar to the upper electrode 21 in the etching processing apparatus 1 described above, a large number of diffusion holes 123 are formed on the surface facing the susceptor 106.
have. An annular ground electrode 124 is provided on the outer circumference of the insulating support material 122 so as to further surround the upper electrode 121. The outer peripheral edge portions of the ground electrode 124 and the ground electrode 115 are shown in FIG.
As shown in, they are installed so as to overlap each other in the vertical direction.

A gas inlet 125 is provided at the center of the upper electrode 121, and an etching gas such as CF ₄ gas from a processing gas supply source 127 is passed through the mass flow controller 126 through the diffusion hole 123 to the processing chamber 1.
02 can be supplied freely. On the other hand, an exhaust pipe 128 leading to a vacuuming means (not shown) such as a vacuum pump is connected to the lower portion of the processing chamber 103, and the processing chamber 102
The inside can be evacuated to any degree of reduced pressure within 5 mTorr to 100 mTorr.

Next, the structure for applying high-frequency power to the susceptor 106 and the upper electrode 121, which are the lower electrode, in the etching processing apparatus 101 will be described. First, to the susceptor 106, the electric power of the relative low frequency power source 131 that outputs the relative low frequency of 800 kHz, for example, is applied via the matching unit 132. This matching device 132
18, the induction coil 133 and the variable capacitor 133 are connected in series, and the other end of the variable capacitor 134 whose one end is grounded is connected in parallel. With this configuration, the impedance of the electric power from the relative low frequency power source 131 is individually controlled by the induction coil 133 and the variable capacitor 133, and the phase thereof is individually controlled by the variable capacitor 134 to achieve matching. It is possible. On the other hand, a high frequency is applied to the upper electrode 121 from a relative high frequency power source 142 that outputs a relative high frequency power having a frequency of 27 MHz, for example, via a matching unit 141.

Etching treatment apparatus 1 according to the second embodiment
The main part of 01 is configured as described above. For example, the operation of etching the oxide film of the silicon wafer W will be described. CF ₄ from the processing gas supply source 127 in the processing chamber 102 will be described. After the gas is supplied and the pressure in the processing chamber 102 is set and maintained at, for example, 10 mTorr, first, the relative high frequency power source 142 applies a relative high frequency of 27 MHz to the upper electrode 121. Then, at a timing of 1 second or less, a relative low frequency of 800 kHz is applied to the susceptor 106 from the relative low frequency power source 131, and plasma is generated between the upper electrode 121 and the susceptor 106. By delaying the application on the susceptor 106 side in this way, there is no possibility that the wafer W is damaged by an excessive voltage.

Then, the silicon oxide film (SiO ₂ ) on the surface of the wafer W is etched by radical components of CF ₄ gas dissociated by the generated plasma. In this case, first, the ground electrode 1 located around the upper electrode 121.
24 and the ground electrode 11 located around the susceptor 106
5, the generated plasma is confined, its diffusion is prevented, and high density is maintained.

In the case of the second embodiment, as shown in FIG. 19 in particular, since the outer peripheral edge portions of the ground electrode 124 and the ground electrode 115 are arranged so as to vertically overlap with each other, the effect of confining the plasma is obtained. Is extremely large.
That is, as shown in FIG. 20, for example, unless the ground electrode 124 is located on the outer periphery and the outer peripheral portions of the ground electrode 124 overlap in the vertical direction, the plasma diffuses to some extent. When the outer peripheral edge portions are vertically overlapped with each other, there is no room for the plasma to diffuse to the outside, and an extremely high density can be secured. Therefore, from this point of view, first, a fine etching process is possible.

According to the inventors, the upper electrode 12
1 and the gap length between 1 and the susceptor 106, the etching rate, the uniformity of the etching rate (distribution of the etching rate on the wafer W), and the stability of the plasma (stability in terms of starting, maintaining, and diffusion of the plasma). It has been confirmed that the relationships shown in FIG.

That is, the longer the gap length, the lower the etching rate (E / R) and the uniformity (U), but the stability (S) of the plasma is improved. In order to realize a high yield and fine etching process, these 3
The two elements need to be secured in a balanced manner,
According to the results obtained by the inventors, as shown in the graph of FIG. 21, it was found that these three elements can be obtained in the most balanced manner when the gap length is around 25 mm.

Regarding this point, in the second embodiment, as described above, the gap length between the upper electrode 121 and the susceptor 106 is set to 25 mm, so that a fine etching process with a high yield is realized for the wafer W. Is possible. Since there are various kinds of desired etching treatment, it is not always necessary to set this to 25 mm, and as can be seen from the graph of FIG.
10 well-balanced etching treatments even in the 35 mm range
A relatively well-balanced etching process can be realized even between mm and 40 mm.

Conventionally, in a plasma processing apparatus using a high frequency of this kind, in order to obtain a high frequency matching, a high frequency power source and an applied electrode, for example, a lower electrode are arranged as shown in FIG. A matching unit 151 is provided. In the conventional matching device 151, variable coils 154 and 155 are arranged in series between a lower electrode 152 and a high frequency power source 153, and a capacitance 156 to be grounded is connected between the variable coils 154 and 155. Had. This allows a wide range of adjustment (matching), but on the other hand, it has a problem that the impedance and the phase cannot be controlled independently, and is easily influenced by the frequency from the upper electrode, for example.

In this respect, in the etching processing apparatus 101 according to the second embodiment, as described above, the induction coil 133 and the variable capacitor 133 are connected in series, and one end of the variable capacitor 134 is grounded. Since the other ends are connected in parallel and the impedance and phase of the power from the relative low frequency power source 131 can be controlled independently, adjustment is easy and the relative high frequency from the upper electrode 121 is high. Are less affected by. Therefore, the generated plasma is extremely stable, and the desired etching treatment can be realized also from this point.

In the etching processing apparatus 101 according to the second embodiment, both the upper electrode 121 and the susceptor 106 are fixed type, and therefore the gap between these electrodes is fixed to 25 mm. In view of the characteristics of 21, the gap length may be variable. For example, as shown in FIG. 23, the gap length d between the upper electrode 121 and the susceptor 106 ′ can be arbitrarily changed if the susceptor 106 ′ is configured to be vertically movable by an appropriate adjusting mechanism 161. It will be possible.

Next, a third embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 24 schematically shows a cross section of an etching processing apparatus 201 according to the third embodiment. The processing chamber 202 is formed in a cylindrical processing container 203 made of aluminum or the like which has been airtightly closed and which can be anodized and oxidized, and the processing container 203 itself is grounded. A substantially cylindrical susceptor 205 for mounting an object to be processed, for example, a semiconductor wafer (hereinafter, referred to as a “wafer”) W is housed in the bottom of the processing chamber 202 via an insulating support plate 204 such as ceramics. The susceptor 205 constitutes a lower electrode.

An annular refrigerant chamber 206 is provided inside the susceptor 205.
Refrigerant for temperature control is introduced through the refrigerant introduction pipe 207, circulates in the refrigerant chamber 206, and is discharged from the refrigerant discharge pipe 208. The cold heat generated during that time is transferred from the coolant chamber 206 to the wafer W via the susceptor 205, and the processing surface of the wafer W can be cooled to a desired temperature. Further, the susceptor 205 is provided with a heating means 209 such as a ceramic heater, and is configured to heat the susceptor 205 to a desired temperature by supplying power from a power source 210 installed outside the processing container 203. Has been done. Therefore, by the cold heat of the coolant chamber 206 and the heating means 209, the wafer W can be set and maintained at a predetermined temperature.

Further, the susceptor 205 is provided with an electrostatic chuck 211, and by applying a DC high voltage from a DC high voltage power source 212 installed outside the processing container 203, the wafer W is placed on the upper surface of the electrostatic chuck 211. Adsorbed and held. In addition, the peripheral edge of the upper end of the susceptor 205 surrounds the wafer W held on the electrostatic chuck 211.
An annular focus ring 213 made of SiO ₂ is arranged. The focus ring 213 is tapered so as to descend from the inner side to the outer side as shown in the drawing.

Above the susceptor 205, facing the susceptor 205 in parallel with a gap length of about 25 mm,
The upper electrode 221 is provided with the processing container 2 via the insulating material 222.
It is supported on the upper part of 03. The upper electrode 221 has a hollow structure, and has a large number of diffusion holes 223 on the surface facing the susceptor 205 and also serves as a discharge portion. An annular gas diffusion guide 224 is provided around the surface of the upper electrode 221 facing the susceptor 205.
The gas diffusion guide 224 is made of SiO ₂ and is supported so as to surround the upper electrode 221.
The opening is tapered toward the susceptor 205 side. Further, in the third embodiment, the taper angle, that is, the angle (angle formed with the horizontal direction) θ formed by the tapered portion 224a as the surface facing the susceptor 205 of the upper electrode 221 is 30 as shown in FIG. It is set to °.

A gas inlet 225 is provided at the center of the upper electrode 221, and is connected to a processing gas supply source via a valve 226. In this embodiment, the valve 22
7. CF ₄ gas from the processing gas supply source 292 via the mass flow controller 228 passes through the valve 230 and the mass flow controller 231 to the processing gas supply source 23.
CHF ₃ gas from each of the 2 is diffused through the diffusion holes 223.
It can be freely supplied to the inside of the processing chamber 202 through.

Exhaust pipes 242, 243, etc. leading to a vacuuming means 241 such as a vacuum pump are connected to the periphery of the lower portion of the susceptor 205 in the processing chamber 202, and the inside of the processing chamber 202 is within 5 mTorr to 100 mTorr. It is possible to evacuate to an arbitrary degree of reduced pressure.

Next, the high frequency power applying system of the etching processing apparatus 201 will be described. First, for the susceptor 205 serving as the lower electrode, for example, the frequency is 800.
Relative low frequency power supply 25 that outputs a relative low frequency of kHz
Power from unit 1 is applied via matcher 252. On the other hand, for the upper electrode 221, through the matching unit 253,
A high frequency is applied from a relative high frequency power source 254 that outputs a relative high frequency power having a frequency of 27 MHz, for example.

A load lock chamber 262 is adjacent to a side portion of the processing container 203 via a gate valve 261. Then, in the load lock chamber 262, the wafer W to be processed is placed in the processing chamber 202 in the processing container 203.
A transporting means 263 such as a transporting arm for transporting between and is provided.

The main part of the etching processing apparatus 201 of the third embodiment is configured as described above. For example, the operation of etching the oxide film of the silicon wafer W will be described. First, the gate valve will be described. After the opening 261 is opened, the wafer W is loaded into the processing chamber 202 from the load lock chamber 262 by the transfer means 263, and is placed on the electrostatic chuck 211 of the susceptor 205.
The transport means 263 is retracted, and the gate valve 261 is closed. Next, the inside of the processing chamber 202 is decompressed by the evacuation means 241, and after a predetermined degree of decompression is reached, CF ₄ gas is supplied from the processing gas supply source 229 and CHF ₃ gas is supplied from the processing gas supply source 232. Supply, processing chamber 2
A pressure of 02 is set and maintained at 10 mTorr, for example.

The relative high frequency power source 254 applies a relative high frequency of 27 MHz to the upper electrode 221, and the relative low frequency power source 251 applies a relative low frequency of 800 kHz to the susceptor 205. Then, plasma is generated between the upper electrode 221 and the susceptor 205, and the generated plasma dissociates the processing gas in the processing chamber 202, and fluorine radicals generated at that time dissociate the silicon oxide film on the surface of the wafer W. (SiO ₂ ) is being etched.

Next, the result of actually etching the oxide film (SiO ₂ ) on the surface of the 6-inch silicon wafer W using the etching processing apparatus 201 will be described. First, the pressure in the processing chamber 202 is 10 mT as described above.
set to orr. The flow rate ratio between CF ₄ gas and CHF ₃ gas was 25/75 sccm. For temperature,
The inside of the processing chamber 202 was set at 20 ° C, the upper portion was set at 30 ° C, and the side portion was set at 40 ° C. Electric power of 2000 W was applied to the upper electrode 221, and electric power of 800 W was applied to the susceptor 205.

As a result of etching the wafer W under such conditions, the results shown in the graph of FIG. 26 were obtained. The graph of FIG. 26 shows the etching rate at a position shifted outward in the diameter direction (X direction, Y direction) from the center of the wafer W. As can be seen from the graph, a position 50 mm away from the center However, the etching rate exceeded 4000 angstroms / min in both the X and Y directions, and the average of the measurement points was 4072 angstroms / min. Regarding the etching rate uniformity (U), U (%) = (ERma
x-ERmin) / 2 · ERave × 100,
U was 6.3 (%). Here, ERmax is the maximum etching rate on the wafer W, ERmin is the minimum etching rate on the wafer W, and ERave is the average etching rate.

In order to compare the above results with those of the prior art, an etching treatment apparatus having a constitution in which only the gas diffusion guide 224 is removed from the etching treatment apparatus 201 of the third embodiment while leaving the other constitutions unchanged, is used under the various conditions described above. The wafer W was etched under exactly the same conditions as above, and the results are shown in the graph of FIG. Comparing the graph of FIG. 26 with the graph of FIG. 27, first, the etching rate of the present embodiment is improved as compared with the conventional one, and the etching rate of about 1000 Å / min is obtained over the entire wafer W. You can see that it is getting higher. By the way, the average etching rate of the measurement points in FIG. 26 is 3142 angstroms / min, and in practice, this example has an average of about 1000 angstroms / m.
The etching rate is high.

As can be seen at a glance about the uniformity, the graph of FIG. 26 has a gentler slope than that of the graph of FIG. 27, and the uniformity of the above-described embodiment is superior. You can confirm that. In fact, the uniformity (U) obtained by the definition of the uniformity (U) in the etching by the conventional etching processing apparatus was 12.3%. Since it was 6.3% in this example as described above, it can be confirmed from this point that the uniformity was improved by this example. Further, the difference in the etching rates at the positions deviated in the X direction and the Y direction is smaller than that in the conventional example, and it is understood that the uniformity of the entire wafer W is improved. Further, since only the gas diffusion guide 224 is provided, the above-mentioned etching rate and uniform processability can be improved, so that the present invention can be carried out by simply modifying the existing device. There is.

Although the etching processing apparatus 201 according to the third embodiment has a structure in which high frequency power having different frequencies is applied to the upper electrode 221 and the susceptor 205 serving as the lower electrode, the present invention is not limited to this. Of course, the present invention can be applied to the etching processing apparatus of. For example, FIG.
As shown in FIG. 7, the processing container 271 and the susceptor 272 are grounded, and the high frequency, for example, 1
A so-called plasma etching (PE) type etching processing apparatus 274 for applying 3.56 MHz, FIG.
, The upper electrode 281 and the processing container 282 are grounded, and the high frequency power is applied to the susceptor 283. Reactive ion etching (RIE)
Type etching processing apparatus 284, and further, as shown in FIG. 30, only the processing container 291 is grounded, and the upper electrode 2
92, a single high-frequency power source 29 for the lower electrode 293
Also for a so-called power split type etching processing apparatus 296 in which electric power of the same frequency from 4 is alternately applied with a phase shifted by 180 ° via a transformer 295,
From the processing gas supply source G, the processing containers 271, 282,
If a tapered annular gas diffusion guide H is provided around each upper electrode 273, 281, 292 having a discharge portion for discharging the processing gas inside 291, the etching rate and uniformity can be improved. is there.

Further, in the etching processing apparatus 201 according to the third embodiment, the susceptor 2 which serves as the lower electrode.
Although the focus ring 213 is installed at the peripheral edge of 05, a gas diffusion exhaust guide 301 may be provided instead of this, as shown in FIG. 31, for example. The gas diffusion exhaust guide 301 has an annular shape as a whole, and has a configuration in which a taper portion 301a inclined downward toward the outer side is provided on the upper surface thereof, that is, on the side of the upper electrode 221. When the gas diffusion exhaust guide 301 having such a configuration is used, the gas conductance on the exhaust side is reduced, and in combination with the gas diffusion guide 224, the gas flow in the processing chamber 202 is further smoothed, and as a result, Further, it is possible to improve the etching rate and uniformity.

The gas diffusion exhaust guide 3 in FIG.
The taper portion 301a of 01 corresponds to the gas diffusion guide 224.
Although the taper angle is set to be parallel to the taper portion 224a, it is not always necessary to set the taper angle to be parallel to that. Further, the gas diffusion exhaust guide 301 may be used together with the focus ring 213. In that case, the gas diffusion exhaust guide may be grounded to the outer circumference of the focus ring. Further, the shape may be integrated with the focus ring.

Gas diffusion exhaust guide 301 as described above
Are not limited to the etching processing apparatus 201 according to the third embodiment, but are of course the plasma etching (PE) type etching processing apparatus 274 shown in FIG. 28 and the reactive ion etching (RIE) processing shown in FIG. It is of course applicable to the etching processing apparatus 284 of the system and further to the etching processing apparatus 296 of the power split method shown in FIG.

By the way, as the device is highly integrated, finer etching process is required, for example, a process of forming a contact hole having a hole diameter of 0.3 μm. In order to realize this, it is necessary to increase the plasma density,
According to the present invention, it is possible to easily realize the above-mentioned etching rate and uniformity while improving the etching rate.

That is, the gas diffusion guide 224 in the etching processing apparatus 201 of the third embodiment is made of a conductive material and is insulated from the upper electrode 221 to be grounded. The gas diffusion exhaust guide 301 shown in FIG. 31 is also made of a conductive material and insulated from the susceptor 205 to be grounded. With this structure, the plasma generated between the upper electrode 221 and the susceptor 205 is confined between the gas diffusion guide 224 and the gas diffusion exhaust guide 301, and its diffusion is prevented. Therefore, the plasma density is improved correspondingly, and a finer etching process becomes possible. Note that such a plasma confinement configuration is also applicable to the plasma etching (PE) type etching processing apparatus 274, the reactive ion etching (RIE) type etching processing apparatus 284, and the power split type etching processing apparatus 296 described above. Of course, it can be applied.
Further, although the etching processing apparatus 201 is configured to apply high frequencies to the upper and lower electrodes, respectively, the etching processing apparatus may be configured to apply high frequency to either the upper or lower electrodes.

Next, a fourth embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 32 schematically shows a cross section of an etching processing apparatus 401 of the fourth embodiment, and a processing chamber in the etching processing apparatus 401. 402 is formed in a cylindrical processing container 403 made of aluminum or the like which is airtightly closable and which is anodized aluminum oxide,
The processing container 403 itself is grounded. An insulating support plate 404 made of ceramic or the like is provided at the bottom of the processing chamber 402.
A substantially columnar susceptor 405 for mounting an object to be processed, for example, a semiconductor wafer (hereinafter, referred to as “wafer”) W, is accommodated via this, and this susceptor 405 constitutes a lower electrode.

An annular coolant chamber 406 is provided inside the susceptor 405, and the coolant chamber 406 includes:
Refrigerant for temperature control is introduced through the coolant introduction pipe 407, circulates in the coolant chamber 406, and is discharged from the coolant discharge pipe 408. The cold heat generated during that time is transferred from the coolant chamber 406 to the wafer W via the susceptor 405, and the processing surface of the wafer W can be cooled to a desired temperature. Furthermore, the susceptor 405 is provided with a heating means 409 such as a ceramic heater, and is configured to heat the susceptor 405 to a desired temperature by supplying power from a power source 410 installed outside the processing container 403. Has been done. Therefore, by the cold heat of the coolant chamber 406 and the heating means 409, the wafer W can be set and maintained at a predetermined temperature.

Further, the susceptor 405 is provided with an electrostatic chuck 411, and by applying a high DC voltage from a high voltage DC power source 412 installed outside the processing container 403, the wafer W is placed on the upper surface of the electrostatic chuck 411. Adsorbed and held. In addition, the upper edge of the susceptor 405 surrounds the wafer W held on the electrostatic chuck 411.
An annular focus ring 413 made of an insulating material is arranged.

Above the susceptor 405, facing the susceptor 405 in parallel, with a gap length of about 25 mm,
The upper electrode 421 is supported on the upper portion of the processing container 403 via the insulating support material 422. This upper electrode 421
Has a thickness of SiO _{2 having} a thickness sufficient to transmit the applied RF power, and has a large number of diffusion holes 423 on the surface facing the susceptor 5.

A gas inlet 424 is provided at the center of the upper electrode 421, and an etching gas such as CF ₄ gas from a processing gas supply source 427 is passed through the diffusion hole 423 through a valve 425 and a mass flow controller 426. It can be freely supplied into the processing chamber 402.

An exhaust pipe 429 communicating with a vacuuming means 428 such as a vacuum pump is connected to the lower portion of the processing container 403, and the inside of the processing chamber 402 is 5 mTorr-10 m.
It is possible to evacuate to any degree of reduced pressure within 0 mTorr.

Next, the high frequency power application system of the etching processing apparatus 401 will be described. First, for the susceptor 405 serving as the lower electrode, for example, the frequency is 800.
Relative low frequency power source 43 that outputs a relative low frequency of kHz
Power from unit 1 is applied via matcher 432. On the other hand, for the upper electrode 421, through the matching unit 434,
A high frequency is applied from a relative high frequency power source 433 that outputs a relative high frequency power having a frequency of, for example, 27.12 MHz.

A load lock chamber 442 is adjacent to a side portion of the processing container 403 via a gate valve 441. In the load lock chamber 442, a transfer unit 443 such as a transfer arm that transfers the wafer W to be processed with the processing chamber 402 in the processing container 403 is provided.

Etching treatment apparatus 4 according to the fourth embodiment
The main part of 01 is configured as described above. For example, the operation when etching the oxide film of the silicon wafer W will be described. First, the gate valve 4 will be described.
After opening 41, the wafer W is transferred by the transfer means 443.
After being loaded into the processing chamber 402 and placed on the electrostatic chuck 411, the transporting means 443 retracts and the gate valve 441 is closed. Next, the inside of the processing chamber 402 is decompressed by the exhaust means 428, and after a predetermined degree of decompression is reached, CF ₄ gas is supplied from the processing gas supply source 427
The pressure of the processing chamber 402 is set to, for example, 10 mTorr,
Maintained.

A relative high frequency of 27.12 MHz is applied to the upper electrode 421 from the relative high frequency power source 433, and with a slight delay (timing delay of 1 second or less) from the relative high frequency power source 433, a relative high frequency is applied to the susceptor 405. And a relative low frequency of 800 kHz is applied from the relative low frequency power source 431, and the upper electrode 421 and the susceptor 40 are
Plasma is generated between 5 and 5. So susceptor 4
By delaying application on the 05 side, it is possible to prevent the wafer W from being damaged by an excessive voltage.

Then, by the generated plasma, the processing chamber 4
The CF ₄ gas in 02 dissociates, and the fluorine radicals generated at that time dissociate the silicon oxide film (SiO 2) on the surface of the wafer W.
₂ ) is etched. In this case, since the upper electrode 421 is made of SiO ₂ , the processing chamber 4
In 02, a reaction such as SiO ₂ + CF ₄ → SiF ₄ + CO 2 occurs, and an atmosphere similar to that in which CO is added to CF ₄ gas which is an etching gas is obtained. Therefore,
Even if the etching of SiO _{2 on} the surface of the wafer W proceeds and the silicon underlayer is exposed, the carbon-rich deposit is generated on the surface of the silicon underlayer by the CO, so that the etching of the silicon underlayer by the fluorine radicals is prevented. To be done. Therefore, the selection ratio is improved.

In the fourth embodiment, the susceptor 405 is used.
Since the focus ring 413 is installed so as to surround the wafer W on the upper surface of the wafer W, the fluorine radicals are efficiently incident on the wafer W during the etching process, and the etching rate of the silicon oxide film (SiO ₂ ) on the surface of the wafer W is It ’s higher, but this focus ring 413
If BN (boron nitride) is used as the material of the above, by the action different from the action of improving the selection ratio by CO,
It is possible to improve the selection ratio.

That is, the fluorine radical (F ^* ) is easily bonded to B of BN, and as a result, a reaction of 2BN + 6F → 2BF ₃ ↑ + N ₂ ↑ occurs, and excess fluorine radical is exhausted through the exhaust pipe 429 into the processing chamber. Since the gas is exhausted from 402, excess fluorine radicals that cause a decrease in the selection ratio are reduced, and as a result, the selection ratio with respect to the silicon underlayer is improved. B
Since N has an insulating property, there is no problem in using it as a material for this type of focus ring.

By the way, it has been conventionally pointed out that various depots that cause contamination adhere to the inner wall of the processing container when appropriate processing is performed on the object to be processed not only in the etching processing apparatus but also in the plasma atmosphere. ing. In view of this point, it has been conventionally performed to heat the processing container 403 itself and suppress the deposition of the depot as described above. However, conventionally, the heating means is provided directly on the outer wall of the processing container 403 to perform the processing. The container 403 was heated.

However, as such, the processing container 403
When it is heated directly from the outside, it conducts heat to the inner wall by conduction, resulting in a large heat loss due to radiation and other factors (ie, poor heat transfer efficiency), and even a very high temperature is required to achieve a given inner wall temperature. Since it is necessary to heat the processing container 403, the maintainability is poor, which is a problem.

As a countermeasure against such a case, it can be proposed to provide a heating member 451 as shown in FIG. 33, for example, along the inner wall of the processing container 403. This heating member 451
Has a substantially annular shape having an outer diameter slightly smaller than the inner wall of the cylindrical processing container 403, and its material is
For example, it is made of quartz or ceramics. A heating element 452 such as a resistance heating element or a ceramic heater is embedded inside the heating member 451, and the heating element 452 is not exposed from the heating member 451. Therefore, it can be used even at a high vacuum degree such as 10 mTorr as described above. The heating element 452 is heated by an appropriate power source 453, and the heating member 51 can be heated and maintained at an arbitrary temperature in the range of 40 ° C to 200 ° C.

The heating member 451 having such a structure is shown in FIG.
Although the inner wall of the processing container 403 can be heated by installing it in the area P shown by the broken line in 2, the heat transfer efficiency is better than that in the conventional case where the outer wall is directly heated, and the maintenance is easy. become.

When the heating member 451 is installed,
It may be hung on the ceiling of the processing container 403, or the susceptor 40
Various methods such as installation on the 5 can be adopted,
In order not to hinder the transfer of the wafer W, the susceptor 405 itself may be configured to be vertically movable, or the heating member 451 itself may be configured to be vertically movable. Further, the heating member 451 itself is not limited to the etching processing apparatus 401 as in the above-described fourth embodiment of the present invention, but can be applied to other plasma processing apparatuses such as a CVD apparatus and a sputtering apparatus.

In the above-mentioned embodiment, the susceptor 405 serving as the lower electrode is supplied with a power of, for example, 800 kHz from the relative low frequency power source 431 which outputs a relatively low frequency, while the upper electrode 421 is applied to the upper electrode 421. On the other hand, the relative high frequency power supply 433 is configured to apply a high frequency of, for example, 27.12 MHz, but when applying high frequencies of different frequencies to the upper and lower electrodes in this way,
As shown in FIG. 35, a high pass filter 461 and a low pass filter 462 may be provided. 35, the members referred to by the same reference numerals as those in FIG. 32 have the same member configurations as those in the fourth embodiment.

That is, one end of a high-pass filter 461 that blocks the intrusion of power of 800 kHz and passes a high frequency of 27.12 MHz is connected in parallel to the application path from the relative low frequency power supply 431 to the susceptor 405, and Ground the ends. On the other hand, in the application path applied from the relative high frequency power supply 433 to the upper electrode 421, 27.12.
One end of a low-pass filter 462 that blocks the intrusion of MHz power and allows a relatively low-frequency power of 800 kHz to pass is connected in parallel, and the other ends are grounded.

With this structure, the 800 kHz power from the relative low frequency power source 431 is input to the susceptor 405 → upper electrode 421 → low pass filter 462, while the 27.1 from the relative high frequency power source 433.
The high frequency power of 2 MHz is supplied from the upper electrode 421 to the susceptor 4.
05 → high-pass filter 461. Therefore, the mutual interference of these two different frequencies of power is prevented, the matching by the matching units 432 and 434 is easily performed, the power loss is reduced, and the upper electrode 421 is reduced.
Power can be efficiently supplied between the susceptor 405 and the susceptor 405.

As described above, power of, for example, 800 kHz is applied to the susceptor 405, while the upper electrode 42
1 is applied with a high frequency of 27.12 MHz,
Ions in the plasma generated at a high frequency of 2 MHz,
The incident velocity is controlled at a relative low frequency of 800 kHz, and in this case, the frequency at which the ions thus etched are controlled, that is, the frequency of the relative low frequency applied to the susceptor 405 is determined. The following points need to be kept in mind.

That is, when a frequency close to the frequency of the relative high frequency applied to the upper electrode 421 side is applied to the susceptor 405, since both frequencies are close to each other, the functions of the high-pass filter 461 and the low-pass filter 462 are hard to exert, and as a result, , Matching may not be performed properly, or power loss may occur. On the other hand, a frequency considerably lower than the frequency of the relative high frequency applied to the upper electrode 421 side,
For example, when an extremely low relative low frequency of 10 kHz is applied to the susceptor 405, the energy width becomes large and the number of ions having high energy increases. As a result, the wafer may be damaged, which is not preferable.

Therefore, in view of the above points, the susceptor 4 is
The frequency of the relative low frequency applied to
It is necessary to select a frequency that is relatively far from the frequency on the one side and does not become extremely low.

In this regard, the inventor has found that the susceptor 405
Vpp in the voltage application path to Vp (the relationship between the plasma voltage and Vpp on the wafer W is determined for each frequency, and the relationship between Vpp on the wafer W and Vdc (self-bias voltage) on the wafer W is determined for each frequency. As a result of considering these characteristics and the energy width of ions at each frequency, 27.12M is applied to the upper electrode 421 of the etching processing apparatus 401.
When applying a high frequency of Hz, considering the impedance of the device, etc., as shown in FIG.
It has been found that it is preferable to supply electric power having a frequency of 800 kHz. According to this, 800 kHz
The relative low-frequency power of is a frequency at which the wafer is less likely to be damaged and is easily matched.
Therefore, the high pass filter 461 and the low pass filter 462 are used, and the upper electrode 421 has 2
When frequency power of 7.12 MHz and 800 kHz is applied to the susceptor 405, the wafer W can be etched without power loss and without damage.

Next, in the etching processing apparatus according to the embodiment of the present invention, the deterioration of the etching processing container can be prevented, and the semiconductor wafer (hereinafter referred to as "wafer") and the like can be surely prevented from being contaminated. 37 and 38 show the technical idea of applying carbon so that
It will be described based on.

The cylindrical etching processing container 501 is made of a material such as aluminum whose surface is anodized, and has a bottomed cylindrical etching processing container 501a.
And an upper portion 501b of the etching processing container, which is arranged in a disk shape and is made of the same material so as to hermetically close the upper opening of the lower portion 501a of the etching processing container. In addition, an O-ring 502 for keeping the inside airtight is appropriately provided at these contact portions.

As shown in FIG. 38, openings 503 and 504 for loading / unloading the wafer W are formed on both sides of the side wall of the lower portion 501a of the etching processing container so as to face each other. Outside the openings 503 and 504, the corresponding gate valves 505 and 506 are provided.
Corresponding load lock chambers 507 and 508 are arranged via the. These load lock chambers 507 and 508
A transfer mechanism 511 for loading and unloading the wafer W is disposed therein (only one is shown in the figure), and usually one load lock chamber, for example, the load lock chamber 50.
7 is dedicated to carry-in, and the other load lock chamber 508 is dedicated to carry-out. In the figure, reference numerals 509 and 510 are gate valves for shutting off and opening the load lock chambers 507 and 508 from the outside.

In the etching processing container 501, an insulating support member 51 made of, for example, ceramics is used.
As shown in FIG. 2, a disk-shaped susceptor, that is, a lower electrode 513, made of, for example, aluminum whose surface is anodized, is provided. The lower electrode 513 is connected to a high frequency power supply 515 via a matching circuit 514, and a cooling medium circulation path 516 for cooling is arranged in the lower electrode 513. The upper surface of the lower electrode 513 is formed in a flat shape so that the wafer W can be attracted and held by, for example, an electrostatic chuck (not shown).

On the other hand, the portion of the etching processing container upper part 501b facing the lower electrode 513 constitutes the upper electrode 521. A gas supply pipe 522 derived from a gas supply source (not shown) is connected to the upper electrode 521, and the predetermined etching gas supplied from the gas supply pipe 522 is a gas formed in the upper electrode 521. A wafer placed on the lower electrode 513 is diffused in the diffusion space 523 by a gas diffusion plate having a large number of through holes, and the multiple through holes 524 formed on the lower surface of the upper electrode 521. It is configured to be uniformly supplied toward W.

An exhaust pipe 532 connected to an exhaust pump 531 is connected to a lower portion of the etching processing container 501, and the lower electrode 5 is provided around the lower electrode 513.
As shown in FIG. 38, a baffle plate 533 having a large number of through holes is horizontally arranged so that the air can be uniformly exhausted from around the area 13.

The baffle plate 533 is made of carbon, and the exhaust pipe 532 is a predetermined distance from the etching processing container 501, for example, about several tens of centimeters to 1 meter, and the inside thereof is a carbon coating film 532.
It is covered with a. The lower surface of the upper electrode 521 is covered with a carbon plate 525, and the inside of the through hole 524 of the upper electrode 521 is covered with a carbon coating film 524a. Further, in the etching processing container 501, a carbon cylinder 534 is arranged so as to cover the inner wall surface thereof.

In the carbon cylinder 534, the above-mentioned 2
Openings 535 corresponding to the two openings 503 and 504, respectively.
Are formed, and carbon shutter plates 536 are provided so as to cover the openings 535 so as to be openable and closable. As shown in FIG. 38, these shutter plates 536 are arc-shaped plate bodies having substantially the same curvature as the inner wall surface of the etching processing container 501. It is connected to an air cylinder 538 provided outside the 501, and is configured to move up and down by the expansion and contraction operation of the air cylinder 538. In addition, for example, a bellows mechanism (not shown) is provided in a penetrating portion of the shaft 537 of the etching processing container 501 as a mechanism for maintaining airtightness between these members.

The carbon members, that is, the baffle plate 533, the plate 525, the cylinder 534, and the shutter plate 536.
Is set to have a thickness of, for example, 1 to 20 mm.

In the etching processing apparatus thus constructed, the exhaust pump 531 is operated in advance to set the inside of the etching processing container 501 to a predetermined degree of vacuum. Then, one of the load lock chambers, for example, the gate valve 509 of the load lock chamber 507 is opened, and the transfer mechanism 51 is opened.
1, the wafer W to be processed is loaded into the load lock chamber 5
07, and then the gate valve 509 is closed to set the inside of the load lock chamber 507 to a predetermined vacuum degree. Then, the gate valve 505 is opened and the shutter plate 536 is moved from the front of the opening 503. , Transport mechanism 5
The wafer W is placed on the lower electrode 513 by 11.

Next, the transport mechanism 511 is retracted from the inside of the etching processing container 501, the gate valve 505 is closed, and the shutter plate 536 is positioned in front of the opening 535. In this state, a predetermined etching gas is supplied from the gas supply pipe 522. For example, Cl ₂ + BCl ₃ is supplied, and together with this, high-frequency power of 515 is supplied from the high-frequency power source 515 to turn the etching gas into plasma, and the wafer W is etched by so-called reactive ion etching. Give.

At this time, all the portions of the etching processing container 501 exposed to the plasma are carbon except the surface of the wafer W. Therefore, for example, the opening 503
Since the gate valve 505 and the inside of the through hole 524 of the upper electrode 521 are prevented from being corroded, it is possible to prevent the wafer W, which is the object to be processed, from being contaminated with aluminum or the like. In addition, the carbon plate 525 and the cylinder 53
4, the shutter plate 536 and the like are etched and consumed, but can be dealt with by replacing these members that can be manufactured at a relatively low cost, and the deterioration of the etching process container lower part 501a, the etching process container upper part 501b, and the like. Can be prevented.

Further, when aluminum is etched, the selectivity of the wafer W can be improved by the action of carbon etched from the plate 525, the cylinder 534, the shutter plate 536 and the like. That is, the side wall protective film made of carbon polymer is easily formed on the side wall of the non-etched portion where the photoresist as the mask is formed on the upper side, so-called undercut of the side wall is suppressed, and the selection ratio is improved. be able to.

Moreover, since the shutter plate 536 is composed of an arc-shaped plate having a curvature substantially similar to the inner wall surface of the etching processing container 501, the etching processing container 5
The plasma generated in 01 is the etching treatment container 5
A uniform and uniform plasma density is obtained along the inner wall surface of 01, the processing of the wafer W is uniformed, and the yield is improved.

In each of the above-described embodiments, the object to be processed is a semiconductor wafer, but the present invention is not limited to this, and the present invention can also be applied to, for example, an LCD substrate to be processed. .

[0170]

According to the plasma processing apparatus of the first to fourth aspects, plasma can be prevented from diffusing to the surroundings from the inter-electrode space in the processing chamber, and the plasma density in the processing region can be improved. On the other hand, the contamination does not occur on the inner wall of the processing chamber. Especially claim 2
When ground electrodes are installed around the first electrode and the second electrode as described above, the effect of confining plasma is large.

When a plurality of magnets are arranged in a substantially annular shape in the vicinity of the periphery of each of the first and second electrodes in the processing chamber to prevent plasma diffusion, only the opposing portion side is set as in claim 4. Instead, by making the magnetic poles between the adjacent magnets different from each other, the plasma diffusion preventing effect can be further improved.

If the current phase difference between the high frequency powers applied to the first electrode and the second electrode is controlled to about 180 ° as in the fifth aspect, the degree of pressure reduction in the processing chamber and the processing can be improved. Regardless of the type of processing gas introduced into the chamber, high-frequency power can be efficiently applied to the plasma to increase the plasma density near the object to be processed.

By setting the gap length between the upper electrode and the lower electrode as in claim 6, for example, in the etching process, a process balanced in etching rate, uniformity, and plasma stability is executed. It is possible.

According to the processing apparatus of the seventh aspect, the gas flow conductance is reduced, the processing gas is more smoothly discharged toward the object to be processed, and the concentration distribution is made uniform.
It is possible to speed up and uniformize the processing.

According to the plasma processing apparatus of claim 8, the effect of claim 7 can be obtained when the object to be processed is processed in a plasma atmosphere. Can improve the etching rate and make the etching uniform. Moreover, the present invention can be applied to existing devices by a simple modification of the device.

According to the ninth aspect, the carbon-rich protective film can be formed on the surface of the underlayer without adding CO to the processing gas, and as a result, an etching process with a high selectivity to the underlayer can be performed. . According to the tenth aspect, excessive fluorine radicals are reduced, and as a result, an etching process having a high selectivity with respect to the underlying layer can be performed. Claim 1
In No. 1, it becomes possible to carry out an etching process with a higher selection ratio.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view of an etching processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a partially cutaway perspective view of a ground electrode used in the etching processing apparatus of FIG.

FIG. 3 is a cross-sectional explanatory view of a processing container using a ground electrode having another structure.

FIG. 4 is a perspective view of a ground electrode having a through hole.

FIG. 5 is a cross-sectional explanatory view of a processing container using a facing type ground electrode.

FIG. 6 is a cross-sectional explanatory view of a processing container that uses a facing-type ground electrode having a sloped portion inside.

FIG. 7 is an enlarged cross-sectional view of essential parts near an upper electrode and a susceptor when a permanent magnet is used as a plasma diffusion preventing means.

FIG. 8 is a perspective view of the permanent magnet shown in FIG.

9 is a bottom view of the insulating member showing how the permanent magnets of FIG. 7 are arranged.

10 is an explanatory diagram showing a state of magnetic pole arrangement of the permanent magnet of FIG. 7. FIG.

11 is a cross-sectional explanatory view showing a state in which a magnetic body is attached to the permanent magnet of FIG.

FIG. 12 is an explanatory diagram showing another magnetic pole arrangement state of a permanent magnet.

FIG. 13 is a cross-sectional explanatory view of a contact hole formed by etching according to a conventional technique.

FIG. 14 is a graph showing a state of output modulation of high-frequency power applied in another example.

FIG. 15 is an explanatory cross-sectional view of a contact hole formed according to the example of the present invention.

FIG. 16 is an explanatory diagram of another embodiment of the present invention in the RIE mode.

FIG. 17 is an explanatory diagram of another embodiment of the present invention in PE mode.

FIG. 18 is an explanatory diagram of an etching processing apparatus of a second embodiment having a configuration for applying high-frequency power having different frequencies to the upper and lower counter electrodes.

FIG. 19 is an explanatory view of a main part of the etching processing apparatus of FIG.

FIG. 20 is an explanatory diagram showing a state where the outer peripheral edge portions of the ground electrode on the upper electrode side and the ground electrode on the lower electrode side do not overlap each other.

FIG. 21 is a graph showing the relationship between the gap length between the upper and lower opposed electrodes, the etching rate, the uniformity, and the plasma stability.

FIG. 22 is an explanatory diagram showing a configuration of a conventional matching device.

FIG. 23 is an explanatory diagram of another embodiment in which the gap length between the upper and lower opposed electrodes is variable.

FIG. 24 is a cross-sectional explanatory view of the etching processing apparatus according to the third embodiment.

25 is an enlarged explanatory view of a main part of a gas diffusion guide in the etching processing apparatus of FIG.

26 is a graph showing the relationship between the position shifted in the radial direction of the wafer and the etching rate when the oxide film of the silicon wafer is etched using the etching processing apparatus of FIG. 24.

FIG. 27 is a graph showing the relationship between the position displaced in the radial direction of the wafer and the etching rate when the oxide film of the silicon wafer is etched using the conventional etching processing apparatus having no gas diffusion guide. .

FIG. 28 is a cross-sectional explanatory view of an embodiment in which a gas diffusion guide is provided around the upper electrode of a plasma etching (PE) type etching processing apparatus.

FIG. 29: Reactive ion etching (RI
It is a cross-sectional explanatory drawing of the Example which provided the gas diffusion guide in the circumference | surroundings of the upper electrode of the E) type etching processing apparatus.

FIG. 30 is a cross-sectional explanatory view of an embodiment in which a gas diffusion guide is provided around the upper electrode of a power split type etching apparatus.

31 is a cross-sectional explanatory view showing a state in which a gas diffusion exhaust guide is installed instead of the focus ring on the susceptor in the etching processing apparatus of FIG. 24.

FIG. 32 is an explanatory cross-sectional view of the etching processing apparatus of the fourth embodiment of the present invention.

FIG. 33 is a perspective view showing an overview of a heating member applicable to the etching processing apparatus of FIG. 32.

34 is a cross-sectional explanatory view of the heating member of FIG. 33.

35 is a cross-sectional explanatory view showing an example in which a high-pass filter and a low-pass filter are used in the etching processing apparatus of FIG. 32.

FIG. 36 is a graph showing the relationship between the energy of incident ions on a wafer and the number of incident ions for each frequency of relative low-frequency power.

FIG. 37 is a cross-sectional explanatory diagram of an etching processing apparatus for explaining a technology for preventing deterioration of a processing container applicable to an embodiment of the present invention.

38 is a cross-sectional view of the etching apparatus of FIG. 37 as seen from a plane.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Etching processing apparatus 2 Processing container 5 Susceptor 15 Focus ring 21 Upper electrode 27 Grounding electrodes 51, 52 High frequency power supply 55, 56 Phase detection means 57 Phase controller W Wafer

 ─────────────────────────────────────────────────── ─── Continuation of front page (31) Priority claim number Japanese Patent Application No. 6-252963 (32) Priority date Hei 6 (1994) September 20 (33) Priority claiming country Japan (JP) (31) Priority Claim number Japanese patent application No. 7-29940 (32) Priority date Hei 7 (1995) January 25 (33) Priority claiming country Japan (JP) (72) Inventor Kazuhiro Tahara 2381 Kitashitajo, Fujii-cho, Nirasaki-shi, Yamanashi No. 1 Tokyo Electron Yamanashi Co., Ltd. (72) Inventor Hiroshi Tsuchiya 2381 Kitashitajo, Fujii-cho, Nirasaki-shi, Yamanashi No. 1 Tokyo Electron Yamanashi Co., Ltd. (72) Inventor Masayuki Tomoyasu 2381 Kitashitajo, Fujii-cho, Nirasaki-shi, Yamanashi Prefecture No. 1 at Tokyo Electron Yamanashi Co., Ltd. (72) Inventor Yukio Naito 2381 Kitashitajo, Fujii-cho, Nirasaki City, Yamanashi Prefecture No. 1 at Tokyo Electron Yamanashi Co., Ltd. (72) Inventor Kazuya Nagaseki Fujii, Nirasaki City, Yamanashi Prefecture Machikitashitajo 1238-1 Tokyo Electron Yamanashi Co., Ltd. (72) Inventor Ryu Nonaka Fujii-cho, Nirasaki-shi, Yamanashi Prefecture 1238 Kitashitajo 1 Tokyo Electron Yamanashi Ltd. (72) Inventor Keise Hirose Fujii Narasaki-shi, Yamanashi Prefecture Machikitashitajo 1238-1 Tokyo Electron Yamanashi Co., Ltd. (72) Inventor Yoshio Fukasawa Fujii Nirasaki-shi Yamanashi Prefecture Fujiicho Kitashitajo 1238-1 Tokyo Electron Yamanashi Co., Ltd. (72) Inventor Koshiishi Fujii Nirasaki Yamanashi 1238 Tokyo Electron Yamanashi Co., Ltd. at 2381 Machikita Shimojo (72) Inventor Isao Kobayashi 1238-1 Kitashitajo Kitashitajo at Fujii-cho, Nirasaki City, Yamanashi Prefecture Tokyo Electron Yamanashi Co., Ltd.

Claims (11)

[Claims] 1. A plasma atmosphere is generated between a first electrode and a second electrode, which are provided facing each other in a processing chamber, by high-frequency power, and the plasma atmosphere is applied to an object to be processed in the processing chamber. In the plasma processing apparatus configured to perform the processing below, a plasma confinement means for confining the plasma in the inter-electrode space is provided around the inter-electrode space in the processing chamber. Plasma processing equipment. 2. A plasma atmosphere is generated between the first electrode and the second electrode, which are provided facing each other in the processing chamber, by high-frequency power, and the plasma atmosphere is applied to an object to be processed in the processing chamber. In the plasma processing apparatus configured to perform the treatment under the first electrode, a substantially annular third electrode is provided near the outer periphery of the first electrode, and a substantially annular first electrode is provided near the outer periphery of the second electrode. The plasma processing apparatus is characterized in that four electrodes are provided, and the third electrode and the fourth electrode are grounded. 3. Plasma is generated between the first electrode and the second electrode facing each other in the processing chamber by high-frequency power, and the plasma atmosphere is applied to the object to be processed in the processing chamber. In a plasma processing apparatus configured to perform a process under a plurality of magnets, a plurality of magnets are arranged in a substantially annular shape in the vicinity of each of the first and second electrodes in the processing chamber, and the magnets are further provided on the first electrode side. A plasma processing apparatus, characterized in that the arranged magnet and the magnet arranged on the second electrode side are opposed to each other, and the magnetic poles of the opposed magnets are different from each other. 4. A plasma atmosphere is generated between the first electrode and the second electrode, which are provided facing each other in the processing chamber, by high-frequency power, and the plasma atmosphere is applied to the object to be processed in the processing chamber. In the plasma processing apparatus configured to perform the processing under a plurality of magnets, a plurality of magnets are arranged in a substantially annular shape in the vicinity of the first and second electrodes in the processing chamber,
Further, the magnet arranged on the side of the first electrode and the magnet arranged on the side of the second electrode are made to face each other, and the magnetic poles of the facing portions of the facing magnets are made different from each other, and The plasma processing apparatus is characterized in that the magnetic poles of the facing portions of the magnets that match each other are also different from each other. 5. Plasma is generated by high-frequency power between a first electrode and a second electrode provided facing each other in the processing chamber, and the plasma atmosphere is applied to an object to be processed in the processing chamber. In the plasma processing apparatus configured to perform the treatment under the following conditions, the high frequency powers applied to the first electrode and the second electrode have the same frequency, and
A plasma processing apparatus comprising means for controlling a current phase difference between two high frequency powers to approximately 180 °. 6. An upper electrode and a lower electrode facing each other vertically in a depressurizable processing chamber, and plasma is generated between the upper and lower electrodes to generate a plasma atmosphere with respect to an object to be processed on the lower electrode. In the plasma processing apparatus configured to perform the treatment under the following conditions, relative high frequency power is applied to the upper electrode, relative low frequency power is applied to the lower electrode, and the upper electrode and the lower electrode are further applied. The plasma processing apparatus is characterized in that the interval length between and is set to 10 to 40 mm. 7. A processing chamber that can be decompressed, and a discharge section located above the processing chamber, discharges processing gas into the processing chamber from the discharge section, and discharges processing gas to an object to be processed in the processing chamber. A processing device configured to perform a predetermined process, characterized in that a gas diffusion guide that is opened in a tapered shape toward the object to be processed is provided at the periphery of the discharge part. 8. A processing chamber which can be decompressed, and an upper electrode and a lower electrode which face each other above and below the processing chamber are opposed to each other, and a processing gas is discharged into the processing chamber from a discharge portion provided on the upper electrode side, Plasma is generated between the upper electrode and the lower electrode,
A plasma processing apparatus configured to perform a process on an object to be processed on the lower electrode, characterized in that a gas diffusion guide that is opened in a tapered shape toward the object to be processed is provided at a peripheral edge of the ejection portion. And a plasma processing apparatus. 9. An upper electrode and a lower electrode are opposed to each other in a depressurizable processing chamber, a processing gas containing C and F is introduced into the processing chamber, and a plasma is generated between these electrodes to generate the plasma. An etching processing apparatus configured to perform etching processing on an object to be processed on an electrode, wherein at least a part of the upper electrode is made of SiO ₂ . 10. An upper electrode and a lower electrode are opposed to each other in a depressurizable processing chamber, a processing gas containing C and F is introduced into the processing chamber, and a plasma is generated between these electrodes to lower the lower electrode. In an etching apparatus configured to perform an etching process on an object to be processed on an electrode, a focus ring is installed around the lower electrode so as to surround the object to be processed, and at least a part of the focus ring is BN. Characterized by being made of a material containing
Etching processing equipment. 11. An upper electrode and a lower electrode are opposed to each other in a depressurizable processing chamber, a processing gas containing C and F is introduced into the processing chamber, and a plasma is generated between these electrodes to generate the plasma. In an etching apparatus configured to perform an etching process on an object to be processed on an electrode, at least a part of the upper electrode is made of SiO ₂ , and a focus is provided around the lower electrode so as to surround the object to be processed. An etching apparatus, wherein a ring is installed, and at least a part of the focus ring is made of a material containing BN.