JPH0794475A - Plasma surface processing device - Google Patents

Abstract

PURPOSE:To provide a plasma surface processing device such that the self-bias voltage can be controlled suppressing fluctuation of a plasma condition. CONSTITUTION:This plasma surface processing device is provided with a vacuum container 1 for processing the surface of a substrate 3 to be processed by a plasma, a lower part electrode 2 provided inside this vacuum container 1 for loading a substrate 3 to be processed, the high-frequency power supply 5 for controlling the potential of this lower part electrode 2 and a dipole ring magnet 8 for producing a magnetic field inside the vacuum container 1 and controlling the angle formed by magnetic line of force incident on the surface of the substrate 3 to be processed and the surface of the substrate 3 to be processed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma surface treatment apparatus using plasma such as a plasma etching apparatus and a plasma CVD apparatus.

[0002]

2. Description of the Related Art In recent years, a large-scale integrated circuit formed by integrating a large number of transistors, resistors, etc., on one chip in an important part of a computer or communication equipment so as to achieve an electric circuit ( LSI) is frequently used. Therefore, the performance of the entire device is largely linked to the performance of the LSI alone.

The performance improvement of the LSI itself can be realized by increasing the degree of integration, that is, by miniaturizing the elements. For this reason, various fine processing techniques have been conventionally developed,
One of them is magnetron RIE (Reactive Ion Etchin
There is g).

FIG. 14 is a schematic diagram showing a schematic structure of a conventional magnetron RIE apparatus. In the figure, reference numeral 81 denotes a vacuum container, and the upper wall of this vacuum container 81 is an upper electrode 82.
Has become. Below the upper electrode 82, a lower electrode 84, which also serves as a substrate support of the substrate 83 to be processed, is arranged so as to face it. The lower electrode 84 is a matching circuit 85.
Is connected to a high frequency power source 86 via an electric field 87, and an electric field 87 can be formed between the upper electrode 82 and the lower electrode 84.

A rotatable magnet 88 is provided above the outside of the vacuum container 81. As a result, a magnetic field is applied to the plasma 89 in the vacuum container 81, and the electrons are confined in the plasma 89. As a result, the plasma density increases.

As described above, the magnetron RIE apparatus can increase the plasma density as compared with the normal RIE apparatus, and thus can increase the etching rate. Further, even when the gas pressure is lowered for the purpose of increasing the directionality of ions or suppressing the reaction (isotropic reaction) between the neutral species and the film to be etched, the cause of damage and selection ratio reduction It is possible to keep sufficiently low ion energy.

However, the conventional magnetron RIE
The device had the following problems. The ions in the plasma 89 are accelerated by the self-bias voltage of the substrate 83 to be processed and enter the substrate 83 to be processed. Therefore, in order to control the motion of ions, it is necessary to control the self-bias voltage.

However, in order to change the self-bias voltage, parameters that affect the plasma state, that is, the pressure inside the vacuum container 81, the magnetic field strength inside the vacuum container 81, the input power of the high frequency power supply 86, and the high frequency power are used. The conditions such as the frequency of the power supply 86 had to be changed.

For this reason, the plasma state greatly changes with the change of the self-bias voltage, and when the plasma state greatly changes in this way, it is very difficult to find the optimum plasma condition.

[0010]

As described above, in the conventional magnetron RIE device, in order to obtain a desired self-bias voltage, conditions such as the pressure in the vacuum container which influences the plasma state and the frequency of the high frequency power source. Had to change. Therefore, if the self-bias voltage is changed,
There is a problem that the plasma state changes greatly.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a plasma surface treatment apparatus capable of suppressing fluctuations in the plasma state and controlling the self-bias voltage.

[0012]

In order to achieve the above object, the surface treatment apparatus of the present invention (Claim 1) forms a treatment chamber in which a substrate to be treated is accommodated and an electric field in the treatment chamber. An electric field forming means, a magnetic field forming means for forming a magnetic field in the processing chamber, and a gas introducing means for introducing a gas for plasmaizing the surface of the substrate to be processed into the processing chamber,
A means for controlling an angle formed by the magnetic force line of the magnetic field on the surface of the substrate to be processed and the surface of the substrate to be processed is provided.

Another surface treatment apparatus of the present invention (claim 2) is a treatment chamber in which the substrate to be treated is accommodated, an electric field forming means for forming an electric field in the treatment chamber, and a magnetic field in the treatment chamber. Magnetic field forming means for forming, gas introducing means for introducing a gas that is turned into plasma to treat the surface of the substrate to be treated into the processing chamber, magnetic force lines of the magnetic field on the surface of the substrate to be treated and the substrate to be treated. And a means for rotating the line of magnetic force around an axis perpendicular to the surface of the substrate to be processed while maintaining the angle formed with the surface of the substrate.

[0014]

The plasma surface treatment apparatus of the present invention (claim 1,
According to 2), the angle formed by the magnetic force line incident on the surface of the substrate to be processed and the surface of the substrate to be processed can be changed. When this angle changes, the electron density near the surface of the substrate to be processed changes and the self-bias voltage changes. Further, even if the angle is changed, the plasma state does not change significantly. Therefore, the self-bias voltage can be controlled while suppressing the fluctuation of the plasma state.

[0015]

Embodiments will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing a schematic structure of an etching apparatus according to the first embodiment of the present invention.

In the figure, 1 indicates a vacuum container, and the upper wall of this vacuum container 1 is an upper electrode 7. Below the upper electrode 7, a lower electrode 2 which also serves as a substrate support of the substrate 3 to be processed is arranged oppositely. The lower electrode 2 is connected to a high frequency power source 5 via a matching circuit 9 so that an electric field can be formed between the upper electrode 7 and the lower electrode 2.

A rotatable dipole ring magnet 8 is provided around the vacuum container 1, and a magnetic field is applied to the plasma in the vacuum container 1 to trap electrons in the plasma. The plasma is formed by the electric field formed between the upper electrode 7 and the lower electrode 2 by the gas introduction port 4
Is performed by discharging the reactive gas introduced into the vacuum container 1.

The dipole ring magnet 8 is shown in FIG.
As shown in (a), sixteen magnet elements 30 arranged so as to concentrically surround the cylindrical vacuum container 1 (see FIG. 15).
(B)), and the magnet element in the position rotated by θ about the central axis from the magnet element 30 magnetized in the magnetic field direction 35 is rotated in the direction 35 ′ by 2θ with respect to the magnetic field direction 35. The magnet elements, which are magnetized and are located 180 degrees from the magnet element 30, are arranged in an annular shape so as to face the magnetic field direction 35 again.

FIG. 2 shows the magnetic field distribution in the vacuum container 1 formed by the dipole ring magnet 8. In this case, the z axis is selected in the direction perpendicular to the surface of the substrate 3 to be processed, the x axis is parallel to the surface of the substrate 3 to be processed, and the x axis is y in the directions orthogonal to each other.
FIG. 2A shows the magnetic field distribution when the axis is selected,
The magnetic field distribution on the y plane is shown, and FIG. 2B shows the magnetic field distribution on the xz plane.

As shown in FIG. 2, the difference in the magnetic field strength from the magnetic field strength at the center in the vicinity of the center inside the dipole ring magnet 8 is less than 20%, and in the xy plane with respect to the magnetic field direction at the center. Inclination of magnetic field direction is ± 7
It can be seen that a uniform magnetic field can be obtained within 0 ° and within ± 9 ° of inclination in the magnetic field direction in the xz plane.

According to this embodiment, the angle between the magnetic force line of the magnetic field formed by the dipole ring magnet 8 and the surface of the substrate 3 to be processed can be changed, and the self-bias voltage can be controlled.

As an example of means for changing the inclination of the magnetic force line incident on the substrate to be processed, there is a method of moving only the dipole ring magnet 8, for example. this is,
By supporting the magnet at a position (EW direction) perpendicular to the N-S direction of polarity in the outer peripheral portion of the dipole ring magnet 8 and gradually raising the N-pole side, for example, with the support being the center, It is possible to gradually increase the inclination of the magnetic force line that is incident on the substrate to be processed. In this way, it is possible to control the inclination of the magnetic force lines that enter the substrate to be processed.

Next, the reason why the self-bias voltage changes when the angle changes will be described with reference to FIG. When a uniform magnetic field B exists in the vacuum container, the electrons in the sheath 11 receive a force defined by the outer product of the electric field E and the magnetic field B, and enter the substrate 3 to be processed while making a spiral motion.

Here, the electric field E is divided into an electric field E _H parallel to the direction of the magnetic field B and an electric field E _v orthogonal to the direction of the magnetic field B, and the electrons move linearly by the electric field E _H , and the electric field E _{H v}
The straight motion is converted into a spiral motion by. The magnitude of the electric field E _v is determined by the angle θ formed by the magnetic force line of the magnetic field B and the surface of the substrate 3 to be processed.

The larger the component of the electric field E _v, the _smaller the component of the electric field E _H , the longer the time that electrons exist in the sheath 11, and the higher the electron density near the sheath 11. The density of the electron density determines the magnitude of the self-bias voltage. Therefore, when the gradient of the magnetic force line is set to an arbitrary θ with the conditions such as the gas introduction pressure kept constant,
This uniquely determines the self-bias voltage. For example, by plotting the relationship between θ and the self-bias voltage under a certain condition, θ for obtaining the desired self-bias voltage can be immediately known. In this way, the self-bias voltage can be controlled by the angle θ.

The plasma state does not change significantly even if the direction of the magnetic field changes. Therefore, according to the present embodiment, the magnitude of the self-bias voltage is not increased by the angle θ between the magnetic force line of the magnetic field formed by the dipole ring magnet 8 and the surface of the substrate 3 to be processed, without causing a large fluctuation in the plasma state. The precision can be controlled precisely, and the optimum self-bias voltage can be selected according to the material to be etched.

Further, if a strong magnetic field, that is, a magnetic field in which the radius of gyration of the spiral motion of the ions is sufficiently smaller than the electrode interval, the diameter of the vacuum container, etc. is used, not only electrons but also ions are confined in the plasma. And high density plasma can be formed.

By densifying the plasma in this way, in addition to simply increasing the etching rate, the directionality of ions is improved, and the reaction between the neutral species and the substrate 3 to be processed (isotropic reaction). Even if the gas pressure is reduced to suppress the above, the ion energy that causes damage and the selection ratio can be kept sufficiently low.

Further, according to the present embodiment, when the surface treatment of the substrate to be treated is performed, even if the optimum self-bias voltage varies depending on the material, the gas used, etc., complicated adjustment of plasma parameters is not required, In addition, even when performing sequential processing or the like, the surface processing can be efficiently performed with an optimum self-bias voltage.

Further, according to the present embodiment, since a uniform magnetic field can be formed by the dipole ring magnet 8, damage due to charge-up on the surface of the substrate to be processed can be reduced.

Various etching processes using the above etching apparatus will be described below. 4A to 4D are process cross-sectional views showing a method of forming a contact portion on the sidewall of the trench groove.

This is an example of an etching process in which ions are obliquely incident on the substrate to be processed from a certain direction to etch only a part of the step portion already formed.

As shown in FIG. 4A, the silicon substrate 2
A trench groove is formed on the surface of 0, and an insulating film 21 serving as a gate insulating film is deposited on the entire surface. The gate electrode 23 and the n ⁺ diffusion layer 2 are on the left side of the trench groove.
4 is formed, and the insulating film 22 is formed on the right side.

Here, the flow rate of CF ₄ gas is 50 cc / min,
Introduced at a pressure of 10 mTorr and high frequency power (13.56
MHz) of 2.7 W / cm ² , the temperature of the lower electrode 2 on which the substrate to be processed is placed is 20 ° C., the inclination angle θ is 10 °, and 3
The insulating film 21 was etched for 0 seconds. The etching rate was 200 to 300 nm / min.

By applying an oblique magnetic field 20 to such a substrate to be processed, ions can be obliquely incident on the substrate to be processed, and as shown in FIG. A part of the insulating film 21 on the side wall can be removed by etching. This is effective, for example, when it is desired to make a contact from the sidewall portion of the capacitor in the trench groove.

The reason why the ions are obliquely incident as described above is considered as follows.

That is, when an oblique magnetic field is applied to the substrate to be processed, the electrons incident on the substrate to be processed are also obliquely incident, and therefore more of the side surface of the etching groove facing the electron incident direction is more exposed. Of the electrons, which causes them to become slightly more negatively charged than the rest. As a result, the trajectories of the incident positive ions are bent, and the ions are also obliquely incident.

Further, as shown in FIG. 5, the substrate to be treated is
When the laminated structure of the lower electrode 26 and the upper electrode 27 is formed in the insulating layer 28, using the resist pattern 25 as a mask, ions are obliquely incident from one direction and etching is obliquely performed. As a result, a contact hole for the lower layer electrode 26 can be easily formed.

6A to 6D are process sectional views showing a method of forming a trench groove.

This is an example of an etching process in which the direction of the magnetic field is changed according to the progress of etching to change the amount of incident ions.

As shown in FIG. 6 (a), when etching is performed to form the trench groove, the deposit 22 adheres to the side wall of the trench groove, and the area of the opening into which the ions enter is narrowed. . Therefore, as the trench groove becomes deeper, the diameter of the trench groove becomes narrower. In order to prevent this, it is necessary to keep the deposit amount of the deposit 22 constant.

In order to realize this, the direction of the magnetic field is changed as the etching progresses, the amount of obliquely incident ions is appropriately selected, and the amount of the deposit 22 is kept constant. At this time, if the magnetic force lines are rotated around an axis perpendicular to the surface of the substrate to be treated while keeping the angle between the magnetic force lines and the surface of the substrate to be treated at a desired value, the magnetic force lines can be oriented in any direction. With respect to all the etched side surfaces, the amount of ions obliquely incident on the etched side surface can be controlled, and as shown in FIG. 6B, the trench groove having the same diameter can be surely formed deep.

The rotation of the magnetic field is carried out by rotating the magnetic field relative to the central axis of the substrate to be processed while keeping the incident angle of the magnetic field constant. The magnetic field can be rotated by rotating the dipole ring magnet, rotating the substrate to be processed, or rotating both the dipole ring magnet and the substrate to be processed. Also, these revolutions need not be at a constant speed.
Further, the angle formed by the substrate to be processed and the magnetic field does not always have to be kept constant during the processing, and may be changed during the processing depending on the processing conditions.

Further, if the incidence of ions is controlled so that the deposition occurs on one side of the etching side surface and the deposit is etched by the incidence of ions on the other side, the side surface of the groove will be partially etched. Only the film can be formed.

Further, by utilizing the oblique incidence of the ions described above, a groove having a larger diameter as it becomes deeper as shown in FIG. 7 or a groove having a smaller diameter as it becomes deeper as shown in FIG. 8 is formed. It can also be formed.

Further, as shown in FIG. 9, when the two trench grooves are arranged side by side, the insulating film on the sidewall of the trench groove in the portion where the n ⁺ diffusion layer 24 is formed is removed by etching, for example, 1 when etching each side wall
The rotation is stopped after every rotation of 80 °, etching is performed for a while, and then further rotated by 180 °. By repeating such etching, as shown in FIG.
A contact portion can be formed in the n ⁺ diffusion layer 24 portion of the two trench grooves.

Next, a method of forming high density plasma by confining electrons will be described.

First, the movement of electrons when the parallel magnetic force lines of the static magnetic field are perpendicularly incident on the surface of the substrate to be processed will be described.

Since there is no electric field in the bulk plasma, the electrons in the plasma make a spiral motion along the lines of magnetic force.

When the electrons reach the sheath, the electrons in the sheath receive a force in the opposite direction due to the electric field in the sheath, and most of the electrons having low energy are returned to the plasma.

When a magnetic field exists in the plasma as described above, the electrons in the plasma move along the lines of magnetic force, and when reaching the sheath, the direction of the movement of the electric field in the sheath is reversed. Change direction.

Therefore, as shown in FIG. 10, a sheath 11a formed between the plasma 10 and the upper electrode 7 and a sheath 11b formed between the plasma 10 and the substrate 2 to be processed.
Between them, electrons can be confined, the electron density can be maintained high, and high-density plasma can be formed. For example,
When an electron having a kinetic energy of 2 eV is moving perpendicularly to a magnetic field in plasma, the electron receives a force from the magnetic field and makes a rotational motion. Since the radius of gyration is inversely proportional to the magnetic field intensity, if the magnetic field intensity is 100 gauss, the radius of gyration of electrons is approximately 477 μm. For this reason,
If a vacuum container with a diameter of about 30 cm is used, the electrons do not collide with the side wall of the vacuum container even if the electrons make a rotational motion, and the spiral motion continues along the magnetic force lines, so that the above-mentioned confinement of electrons is realized. It is possible to form high density plasma.

According to the above method, the substrate to be processed comes into contact with the high density plasma, so that high speed etching can be performed. Furthermore, since the magnetic field strength is constant and the lines of magnetic force are parallel, it is possible to form a plasma with good uniformity, so that surface treatment with very good in-plane uniformity can be performed.

Further, as shown in FIG. 11, by making the magnetic field on the side wall of the vacuum vessel 1 stronger than the magnetic field on the central part of the vacuum vessel 1, the electrons escaping to the side wall of the vacuum vessel 1 can be efficiently confined. it can. Therefore, the plasma density can be further increased, and higher speed etching can be realized.

Furthermore, by using a stronger magnetic field,
Even ions can be confined between the electrodes. For example, when argon ions (Ar ⁺ ) are moving at a kinetic energy of 2 eV in a plasma perpendicular to a magnetic field, a vacuum container having a diameter of 30 cm is used and the magnetic field strength is 10 ⁴ gau.
With ss, the radius of gyration of argon ions is 1.27 m.
m. Therefore, even if the argon ions make a rotational motion, the argon ions do not collide with the side wall of the vacuum container or the like, so that the argon ions can be confined and high-density plasma can be formed.

Further, since the ions enter the substrate to be processed while making a spiral motion, as shown in FIG. 12, when the substrate to be processed is etched using the resist pattern 25 having irregularities on the side wall of the opening as a mask. Even if there is, the convex portion is also etched during the etching and the unevenness is relaxed, so that the unevenness of the resist pattern 15 is not transferred to the base.

Next, a method of forming a via hole capable of removing the deposits on the sidewall will be described.

FIGS. 13A and 13B are process sectional views showing a method of forming a via hole when a conventional etching apparatus is used. The layers below the insulating layer 28 and the substrate are omitted.

First, as shown in FIG. 13A, after forming a photoresist pattern 25 for forming a via hole of an Al wiring 29 on an insulating layer 28, for example, CHF ₃ or CF ₄ and H ₂ are mixed. The insulating layer 28 is etched using gas to expose the Al wiring 29.

At this time, the side wall deposit 30 is deposited on the side surface of the via hole. This is because, for example, ions bombard the surface of the Al wiring 29 and the Al wiring 29 is sputtered,
This is because Al adheres to the side surface of the via hole. The main component of the sidewall deposit 3 is Al or an oxide thereof, and as other components, a component of the photoresist pattern 25 (for example, carbon), a part of the component of the insulating film 28, and the like are included.

Next, when the photoresist pattern 25 is removed by resist stripping means such as O ₂ plasma ashing, as shown in FIG. 13B, the sidewall deposits 29a are left higher than the surface of the insulating film 29.

In this state, if the via hole is filled with W by the selective CVD method, for example, there is a problem that abnormal growth occurs on the surface of the side wall deposit 29a.

Such a problem can be solved by, for example, the etching apparatus shown in FIG.

To explain this concretely, first, CF ₄
Flow rate of 80 cc / min, H ₂ flow rate of 80 cc / min, O
Set the flow rate of ₂ to 1 cc / min and set the gas pressure to 50
mTorr, high frequency power (13.56MHz) 2.7W / cm
^2. The temperature of the lower electrode 2 on which the substrate to be treated is placed is 20 ° C.
The magnetic field strength is 400 gauss, the angle between the magnetic field and the substrate to be processed is 0 ° (that is, the substrate and the magnetic field are parallel to each other), and the insulating film 28 is etched to obtain the shape shown in FIG.

At this time, the etching rate is about 550 nm.
/ Min, and the film thickness to be etched is 1.2 μm,
50% over etching was performed. That is, the etching time was 3 minutes and 16 seconds.

Next, the angle between the magnetic field and the substrate to be treated is set to 60.
The magnetic field strength is set to 400 gauss, the H ₂ flow rate is 80 cc / min, and the O ₂ flow rate is 40 cc.
/ Min, gas pressure 100 mTorr, high frequency power (13.5
6 MHz) was set to 1 W / cm ² , the temperature of the lower electrode 2 on which the substrate to be processed was placed was set to 20 ° C., and etching was performed for 1 minute. In addition, at this time, the center of the axis perpendicular to the surface of the substrate to be treated
The magnetic field was rotated at a speed of 0 times / minute.

At this time, as shown in FIG. 13C, the electrons travel along the magnetic field while being wrapped around the magnetic field, and enter the substrate to be processed. Some of the electrons that enter the substrate to be processed enter the sidewall of the via hole, so that the sidewall of the via hole is negatively charged. As a result, the side wall of the via hole is heavily bombarded with ions having a large mass, whereby the side wall deposition film 29a is removed by etching.

Al in the sidewall deposited film 29a is easily removed as an AlF compound having a high sputter yield due to F released from the inner wall of the vacuum container and the fluorocarbon film attached to the surface of the photoresist pattern.

Therefore, as a result of the above steps, FIG.
Etching without sidewall deposits is achieved as shown in (d).

As described above, according to the above embodiment,
It is possible to improve the film forming speed, the selectivity, the processing accuracy, and the damage. Furthermore, since high-density plasma can be formed, the decomposition and reaction of gas in the gas phase proceeds, so that the film quality can be improved.

Next, an example in which the present invention is applied to an ion implantation technique will be described.

First, a silicon substrate as a substrate to be processed is carried into a reaction chamber of a parallel plate type plasma apparatus, and then, for example, BF3 gas containing boron as a dopant is introduced to form plasma. BF ₃ molecules are dissociated in the plasma, and B ions among them are implanted into the substrate to be treated.

At this time, as in the previous embodiment, B ions are implanted with a dipole ring magnet used and a magnetic field formed in the reaction chamber. In addition to B ions, a large amount of neutral active F is also generated. Therefore, in order to prevent etching of the substrate to be processed, the above process is performed at 10 ⁻⁵ To
Processing is performed under high vacuum of rr level.

As described above, by applying a magnetic field, high-density plasma can be generated even under high vacuum as described above.
Ion implantation can be performed with a low ion energy of 0 to several 100 eV, so that an extremely shallow impurity layer can be formed.

By controlling the direction of the magnetic field,
By implanting ions at an angle of about 7 degrees with respect to the (100) plane of the silicon substrate, it is possible to prevent ion channeling. Furthermore, by rotating the dipole ring magnet while keeping the direction of the magnetic field constant, it is possible to prevent the mask from causing a shadow of the incident ions.

Further, for the purpose of implanting ions under the mask, it is possible to implant ions by intentionally making an incident angle with respect to the substrate to be processed. Also in this case, ion implantation can be performed from the optimum direction by arbitrarily setting the direction of the magnetic field.

The present invention can also be applied to a sputtering device.

In this case, for example, the sputtering rate of the target can be controlled by changing the angle between the surface of the target and the line of magnetic force. As a result, the film formation speed can be controlled, and the film formation can be performed at an optimum film formation speed for the film thickness.

The present invention can be applied to both a sputtering apparatus that applies high-frequency power and a sputtering apparatus that applies DC power.

Furthermore, the present invention can be applied to a plasma CVD apparatus.

In this case, for example, the self-bias voltage generated between the substrate to be processed and the plasma can be controlled by changing the angle between the surface of the substrate to be processed and the line of magnetic force.
The energy of the ions incident on the substrate to be processed can be controlled. That is, the deposition rate can be arbitrarily changed by the angle, and the film thickness can be precisely controlled.
Further, as shown in FIG. 11, if the magnetic field strength is selected, a high plasma density can be realized, and the film formation rate can be increased as compared with the conventional plasma CVD apparatus.

Although the embodiment in which the present invention is applied to the plasma etching apparatus, the plasma CVD apparatus, the sputtering apparatus, etc. has been described above, the present invention is not limited to the plasma surface reforming apparatus, the plasma ion source of the ion implantation apparatus,
It can also be applied to an ECR device and a device that forms a Whistler wave (helicon wave) plasma and uses it as a source of plasma, electrons, ions, and neutral active species.

The magnetic field strength varies depending on each process, but is preferably several Gauss or more. Also, the lower electrode 2,
High frequency or DC power may be supplied to the upper electrodes 7 individually. Furthermore, if the material of the surface of the upper electrode 7 is selected so that the potential of the surface of the upper electrode 7 which is in contact with the plasma becomes floating, the confinement of electrons and ions can be further enhanced, and high-density plasma can be formed. .

In the above-mentioned embodiment, 13.56 MHz is selected as the frequency of the high frequency power. However, depending on the material to be etched, for example, in the case of oxide film type etching requiring a high ion energy, the frequency is from 100 kHz. A relatively low frequency of about 1 MHz is effective. on the other hand,
When selectivity is required for the underlying substrate such as polycrystalline silicon added with phosphorus or aluminum alloy, and relatively low ion energy is required, 20 MH
A high frequency from z to several hundred MHz is effective.
In any case, the ion energy, plasma density, and other plasma parameters suitable for processing are controlled in combination with the magnetic field strength. As for the gas to be used, in the case of the trench groove, since the silicon substrate was assumed, chlorine-based gas was used as the etching gas, but fluorine-based gas or Cl-F-based gas may be used. Further, in the case of anisotropic etching of a silicon oxide film, a fluorocarbon (CF) -based gas, in the case of etching a silicon nitride film, a fluorine-based gas, and in the case of etching a metal used for wiring or the like, a chlorine-based gas. A gas such as a fluorine-based gas or a gas containing oxygen in the case of etching a resist may be appropriately selected according to the material to be etched. Further, an inert gas, hydrogen gas, nitrogen gas, oxygen gas or the like may be added.

In the above embodiment, a dipole ring magnet is used to form a magnetic field in the vacuum chamber and to control the angle between the magnetic force line incident on the surface of the substrate to be processed and the surface of the substrate to be processed. Although used, it may be realized by other means.

In addition, various modifications can be made without departing from the scope of the present invention.

[0088]

As described in detail above, according to the present invention, since the self-bias voltage can be controlled while suppressing the fluctuation of the plasma state, a favorable plasma surface treatment can be performed.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of an etching apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a magnetic field in a dipole ring magnet of the etching apparatus of FIG.

FIG. 3 is a diagram for explaining the reason why self-bias can be controlled.

FIG. 4 is a process sectional view showing a method of forming a contact portion on a sidewall of a trench.

FIG. 5 is a cross-sectional view illustrating a method of forming a contact hole.

FIG. 6 is a sectional view for explaining a method of forming a trench.

FIG. 7 is a cross-sectional view showing an inverted taper groove.

FIG. 8 is a cross-sectional view showing a forward tapered groove.

FIG. 9 is a sectional view for explaining a method of forming a contact portion on a sidewall of a trench.

FIG. 10 is another diagram for explaining the electron confinement method.

FIG. 11 is a diagram showing the magnetic field strength with which the plasma density is increased.

FIG. 12 is a diagram for explaining the reason why the unevenness of the resist pattern is alleviated.

FIG. 13 is a diagram for explaining a method of forming a via hole that can remove deposits on a sidewall.

FIG. 14 is a schematic diagram showing a schematic configuration of a conventional magnetron RIE device.

FIG. 15 is a diagram for explaining a dipole ring magnet.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Vacuum container 2 ... Lower electrode 3 ... Processed substrate 4 ... Gas inlet 5 ... High frequency power supply 6 ... Exhaust port 7 ... Upper electrode 8 ... Dipole ring magnet 9 ... Matching circuit 10 ... Plasma 11 ... Sheath 20 ... Silicon substrate 21 ... Insulating film 22 ... Insulating film 23 ... Gate electrode 24 ... N ⁺ diffusion layer 25 ... (Photo) resist pattern 26 ... Lower layer electrode 27 ... Upper layer electrode 28 ... Insulating layer 29 ... Al wiring 29a ... Side wall adhering matter

Claims (2)

[Claims] 1. A processing chamber in which a substrate to be processed is housed, an electric field forming means for forming an electric field in the processing chamber, a magnetic field forming means for forming a magnetic field in the processing chamber, and the substrate to be processed by plasma conversion. A gas introduction unit for introducing a gas for treating the surface into the treatment chamber; and a unit for controlling an angle formed by the magnetic force line of the magnetic field on the surface of the substrate to be treated and the surface of the substrate to be treated. A plasma surface treatment apparatus characterized by the following. 2. A processing chamber in which a substrate to be processed is housed, an electric field forming means for forming an electric field in the processing chamber, a magnetic field forming means for forming a magnetic field in the processing chamber; A gas introduction unit for introducing a gas for treating the surface into the treatment chamber; and the magnetic force line while maintaining an angle between the magnetic force line of the magnetic field on the surface of the substrate to be treated and the surface of the substrate to be treated. And a means for rotating the substrate about an axis perpendicular to the surface of the substrate to be treated.