JPH0536635A - Plasma treatment method and equipment - Google Patents

Abstract

PURPOSE:To generate stable plasma in a plasma treatment chamber when gases to be used are different in kind. CONSTITUTION:A permanent magnet 7 which is a magnetic field generating means for assisting plasma generation is fixed to a slide base 8 constituting a magnetic field intensity adjusting means, said slide base 8 is moved with a screw 9, and it is made able to move the permanent magnet 7 in the direction where the permanent magnet Y approaches the outer wall surface of a plasma treatment chamber 1 or separates therefrom.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing method and apparatus used for etching, plasma CVD and the like in the process of manufacturing a semiconductor element, and particularly to a plasma suitable for stable and reproducible plasma processing. A processing method and apparatus.

[0002]

2. Description of the Related Art In recent years, in order to achieve high integration of semiconductors,
The dimensions of semiconductor elements have been reduced from 0.5 μm to 0.3 μm. In order to accurately etch such a fine pattern, dry etching using plasma is used.

In the processing using plasma like the dry etching, there is a problem that the characteristics of the semiconductor element are affected when the plasma becomes unstable. Therefore, in order to form a semiconductor element having a thickness of 0.3 to 0.5 μm with good performance, it is important to generate stable plasma.

By the way, as a conventional technique for generating plasma, there is a technique described in Japanese Patent Application No. 1-27406. In this conventional technique, microwaves are supplied from a slot antenna to generate plasma.

On the other hand, in dry etching, it is necessary to change the etching gas as a processing gas depending on the target film. However, as the processing gas is changed, the situation of plasma generation varies greatly. This is because the ionization energy and collision cross section differ depending on the characteristics of the processing gas. Therefore, in order to form stable plasma, it is necessary to generate plasma according to the characteristics of these processing gases.

[0006]

However, the prior art does not take into consideration the fact that the intensity of the magnetic field is changed according to the characteristics of the processing gas used to generate stable plasma. Therefore, there is a problem that stable plasma cannot be generated depending on the type of processing gas.

A first object of the present invention is to provide a plasma processing method which can be adjusted so that stable plasma can be generated even if the type of processing gas used is different.

A second object of the present invention is to provide a plasma processing apparatus capable of accurately carrying out the plasma processing method.

[0009]

The first object is achieved by changing the strength of the magnetic field that assists the generation of plasma in accordance with the characteristics of the processing gas used.

The first object is to provide a plasma processing method in which different kinds of processing gases are supplied into the plasma processing chamber at a predetermined time interval and the processing is performed. It is achieved by changing the characteristics of the processing gas of

Further, the second object is achieved by attaching magnetic field intensity adjusting means for changing the intensity of the magnetic field according to the characteristics of the processing gas to the magnetic field generating means for assisting the generation of plasma.

A second object of the present invention is to provide a plasma processing apparatus using a permanent magnet as the magnetic field generating means, wherein the magnetic field strength adjusting means separates the position of the permanent magnet from the outer wall surface of the plasma processing chamber. It is more achieved by being configured to be movable in any direction, and further, in a plasma processing apparatus using a solenoid as the magnetic field generating means, the magnetic field strength adjusting means being configured to be able to control the electric power supplied to the solenoid. To be done.

[0013]

In general, when a processing gas that requires a large ionization energy is used, it is necessary to increase the magnetic flux density, prolong the life of electrons, and increase the probability of ionization.

On the other hand, when a processing gas having a low ionization energy is used, if the magnetic flux density is too high, the probability of ionization becomes high, so that the plasma density is partially increased and the microwave absorption is increased. Etc. changes, and an unstable state occurs such that a region with high plasma density moves. As described above, in the case of using the processing gas having a small ionization energy, the probability of ionization is reduced by decreasing the magnetic flux density, the plasma density is not partially increased, and stable plasma can be obtained. .

Therefore, in the invention according to the first aspect of the present invention, the strength of the magnetic field for assisting the generation of plasma is changed in accordance with the characteristics of the processing gas used.
That is, when a processing gas requiring a large ionization energy is used, the strength of the magnetic field that assists the generation of plasma is increased, the magnetic flux density is increased, the life of electrons is lengthened, and the probability of ionization is increased. On the contrary, when a processing gas that requires a small ionization energy is used, the strength of the magnetic field that assists the generation of plasma is reduced, the magnetic flux density is lowered, and the probability of ionization is lowered.

As a result, in the invention according to the first aspect, even in the plasma processing using the processing gas having different characteristics, stable plasma can be generated according to the characteristics of the processing gas used.

By the way, a plasma treatment is carried out in which two or more layers of films having different properties are formed on a single substrate, and each film is etched by using etching gases having different properties to continuously etch the multilayer film. There is. In such plasma processing, processing gases having different characteristics are supplied into the plasma processing chamber at time intervals.

Therefore, in the invention according to claim 2 of the present invention, whenever the processing gas supplied to the plasma processing chamber changes, the strength of the magnetic field for assisting the generation of plasma is optimized in accordance with the characteristics of the processing gas. Change to.

As a result, stable plasma can be generated even in the case of plasma processing using different kinds of processing gases at time intervals.

According to the third aspect of the present invention, the magnetic field intensity adjusting means is attached to the magnetic field generating means for assisting the generation of plasma. Then, the state of the magnetic field generating means is changed through the magnetic field strength adjusting means according to the characteristics of the processing gas to be used, and the strength of the magnetic field for assisting the generation of plasma is appropriately changed.

As a result, stable plasma can be generated according to the characteristics of the processing gas to be used, and the method of the present invention can be carried out accurately.

According to the invention of claim 4 of the present invention,
In the plasma processing apparatus using a permanent magnet as the magnetic field generating means, the magnetic field strength adjusting means is configured so that the position of the permanent magnet can be moved in a direction of approaching or separating from the outer wall surface of the plasma processing chamber. According to a fifth aspect of the invention, in the plasma processing apparatus using a solenoid as the magnetic field generating means, the magnetic field strength adjusting means is
It is configured to control the power supplied to the solenoid,
It becomes possible to carry out the above-mentioned method of the present invention more accurately.

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical sectional view showing a first embodiment of a plasma processing apparatus for carrying out the method of the present invention.

In the plasma processing apparatus shown in FIG. 1, a stage electrode 2 is installed inside a plasma processing chamber 1, and a quartz window 3 for radiating a microwave is installed on a surface facing the stage electrode 2. There is. The quartz window 3 has a vacuum seal structure. The inside of the plasma processing chamber 1 is connected to an exhaust system (not shown) through an exhaust pipe 5 and is evacuated to a vacuum.

A substrate 4 to be processed is placed on the stage electrode 2. Also, the stage electrode 2
A high frequency power source 6 is connected to the high frequency power source 6, and a high frequency bias is applied by the high frequency power source 6 during plasma processing.

Around the quartz window 3, a plurality of permanent magnets 7 are provided as magnetic field generating means for assisting plasma generation. In this embodiment, twelve permanent magnets 7 are arranged with alternating polarities and are evenly spaced on the circumference. The permanent magnet 7 is fixed on a slide base 8. The slide base 8 can be slid by a screw 9. The slide base 8 and the screw 9 constitute magnetic field strength adjusting means for moving the permanent magnet 7 in a direction of approaching and separating from the outer wall surface of the plasma processing chamber 1. Also, the plasma processing chamber 1
The permanent magnets 17 are also attached in two steps on the outer wall surface of the. The permanent magnet 7 and the permanent magnet 17 form a multi-pole cusp magnetic field to prevent the generated plasma from diffusing out of the plasma processing chamber 1 and form a uniform plasma.

A buffer chamber 10 of a processing gas supply unit is formed below the row of the permanent magnets 7. A processing gas is supplied to the buffer chamber 10 through a processing gas supply source (not shown) and a processing gas supply pipe 12. The buffer chamber 10 has a blowout port 11
Through, the processing gas is evenly supplied into the plasma processing chamber 10.

Above the quartz window 3, a cavity resonator 13 is provided.
Is installed. This cavity resonator 13 is made in the TM01 mode. A coaxial waveguide 15 is connected to the cavity resonator 13 so that the electric field direction is aligned with the mode. The coaxial waveguide 15 is connected to a microwave power source (not shown). The slot 1 of the slot antenna is provided on the surface of the cavity resonator 13 on the quartz window 3 side.
A plurality of 4 are provided. Each slot 14 is provided in a direction perpendicular to the electric field in the cavity resonator 13 so that microwaves can be efficiently radiated from the cavity resonator 13 into the plasma processing chamber 1.

Next, an example of the plasma processing method of the present invention will be described with reference to the operation of the plasma processing apparatus of the first embodiment.

CL ₂ as an etching gas is supplied from the processing gas supply pipe 12 and exhausted from the exhaust pipe 5 to set the pressure in the plasma processing chamber 1 to 0.5 Pa.

The substrate 4 to be processed is placed on the stage electrode 2, and a high frequency bias is applied to the stage electrode 2 through a high frequency power source 6.

Then, a microwave of 2.45 GHz is generated from a microwave power source (not shown), the microwave is oscillated by the coaxial waveguide 15 and supplied to the cavity resonator 13, and the microwave is slotted. The energy density is increased by the slot 14 of the antenna and is uniformly radiated into the plasma processing chamber 1 to generate plasma.

Then, the screw 9 is rotated to move the slide base 8 so that each permanent magnet 7 approaches and separates from the outer wall surface of the plasma processing chamber 1 in accordance with the characteristics of the etching gas CL ₂ used. And is adjusted so that stable plasma can be generated in the plasma processing chamber 1.

As a result of the experiment, when the etching gas is CL ₂ and the position of each permanent magnet 7 is set to a position about 100 mm away from the outer wall surface of the plasma processing chamber 1, the magnetic flux density in the plasma processing chamber 1 is determined by the plasma processing. It becomes 0.09 T or less near the inner wall surface of the chamber 1, and in this state, the multipole cusp magnetic field formed by the permanent magnets 7 and 17 prevents the diffusion of plasma to the outside of the plasma processing chamber 1, A uniform plasma could be formed on the substrate 4 placed on the electrode 2, and stable plasma could be generated.

On the other hand, when the position of the permanent magnet 7 is set to a position separated from the outer wall surface of the plasma processing chamber 1 by about 2 to 3 mm, the magnetic flux density near the inner wall surface of the plasma processing chamber 1 is about 0.13T. Becomes In this state, of the slots 14 of the slot antenna, a part where only some of the slots 14 emit light brightly appears, and the light emission position moves to below the other slots 14.

On the other hand, when the etching gas is SF ₆ , the pressure of the etching gas in the plasma processing chamber 1 is 1 Pa or less when the permanent magnet 7 is set at a position 10 mm away from the outer wall surface of the plasma processing chamber 1. Almost no plasma was generated. On the other hand, when the permanent magnet 7 was set at a position 2 to 3 mm away from the outer wall surface of the plasma processing chamber 1, stable plasma could be generated up to an etching gas pressure of 0.3 Pa.

As described above, when the permanent magnet 7 is used as the magnetic field generating means for assisting the plasma generation, the permanent magnet 7 approaches the outer wall surface of the plasma processing chamber 1 according to the characteristics of the processing gas used. By moving in the separating direction, stable plasma can be generated in the plasma processing chamber 1.

Next, when etching a multi-layered film on a single substrate 4, different kinds of etching gases are supplied at time intervals and processed. In the case of etching gas that requires a large ionization energy during such plasma processing, the permanent magnet 7 is moved in a direction approaching the outer wall surface of the plasma processing chamber 1 via the slide base 8 and the screw 9. Increase the magnetic flux density and increase the probability of ionization. On the other hand, in the case of an etching gas that requires only a small ionization energy, the permanent magnet 7 is moved in a direction away from the outer wall surface of the plasma processing chamber 1 via the slide base 8 and the screw 9 to lower the magnetic flux density and to reduce the ionization. Lower the probability.

As a result, the multilayer film can be continuously etched.

In the first embodiment, the screw 9
May be connected to a reversible motor and automatically rotated.

Next, FIG. 2 is a vertical sectional view showing a second embodiment of the plasma processing apparatus for carrying out the plasma method of the present invention.

In the plasma processing apparatus of the second embodiment, a solenoid 18 is provided as the magnetic field generating means in place of the permanent magnet 7 described above.

The solenoid 18 is connected to a power source 19. The power supply 19 is provided with a controller 20 as a magnetic field strength adjusting means.

In the second embodiment, the controller 20 controls the electric power supplied from the power source 19 to the solenoid 18 in accordance with the characteristics of the processing gas to be used to generate stable plasma in the plasma processing chamber 1. I am trying to let you.

The other structure and operation of the second embodiment are the same as those of the first embodiment.

[0047]

According to the invention described in claim 1 of the present invention described above, the strength of the magnetic field for assisting the generation of plasma is
Since it is changed according to the characteristics of the processing gas used, there is an effect that stable plasma can be generated in the plasma processing chamber even if the type of processing gas used is different.

According to the second aspect of the present invention, in the plasma processing method of supplying and processing different kinds of processing gas into the plasma processing chamber at a predetermined time interval, Since the strength of the magnetic field is changed according to the characteristics of each processing gas, even when etching a multi-layer film formed on a single substrate with etching gases having different characteristics, It becomes possible to generate stable plasma in accordance with the characteristics of the etching gas which is the processing gas of (3), and therefore, it is possible to continuously process a multilayer film.

Further, according to the third aspect of the present invention, the magnetic field strength adjusting means for changing the strength of the magnetic field according to the characteristics of the processing gas is attached to the magnetic field generating means for assisting the generation of plasma. Therefore, the strength of the magnetic field can be changed in accordance with the characteristics of the processing gas to be used, and stable plasma can be generated in the plasma processing chamber. Therefore, the method of the present invention can be carried out appropriately.

According to a fourth aspect of the present invention, in the plasma processing apparatus using a permanent magnet as the magnetic field generating means, the magnetic field strength adjusting means is arranged so that the position of the permanent magnet is outside the plasma processing chamber. It is configured to be movable in a direction of approaching and separating from a wall surface, and the invention according to claim 5
According to the invention described above, in the plasma processing apparatus using a solenoid as the magnetic field generating means, the magnetic field strength adjusting means is configured to be able to control the electric power supplied to the solenoid. There is an effect that can be implemented more accurately.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a first embodiment of a plasma processing apparatus for carrying out the method of the present invention.

FIG. 2 is a longitudinal sectional view showing a second embodiment of the plasma processing apparatus for carrying out the method of the present invention.

[Explanation of symbols]

1 ... Plasma processing chamber, 2 ... Stage electrode, 3 ... Quartz window,
4 ... Substrate, 6 ... High frequency power source, 7 ... Permanent magnet which is a magnetic field generating means for assisting plasma generation, 8 ... Slide base which constitutes magnetic field strength adjusting means of permanent magnet, 9 ... Screw for moving the slide base 10 ... buffer room, 11
... Processing gas outlet, 12 ... Processing gas supply pipe, 13
… Cavity resonator, 14… Slot antenna slot, 1
5 ... Coaxial waveguide, 17 ... Permanent magnet, 18 ... Solenoid as magnetic field generating means for assisting plasma generation, 19 ... Solenoid power supply, 20 ... Controller as magnetic field strength adjusting means.

Claims (5)

[Claims] 1. A plasma processing method in which microwaves are radiated from a slot antenna into a plasma processing chamber to generate plasma and a processing gas is supplied into the plasma processing chamber to perform plasma processing on a substrate to assist plasma generation. A plasma processing method characterized in that the strength of a magnetic field is changed according to the characteristics of a processing gas to be used. 2. In a plasma processing method, wherein different kinds of processing gases are supplied into a plasma processing chamber at predetermined time intervals to process the plasma, the strength of the magnetic field is adjusted to the characteristics of each processing gas. 2. The plasma processing method according to claim 1, wherein the plasma processing method is changed. 3. A plasma generating means for generating a plasma by radiating a microwave into the plasma processing chamber from a slot antenna, a magnetic field generating means for assisting the generation of the plasma, and a processing gas supply for supplying a processing gas into the plasma processing chamber. A plasma processing apparatus having a section, wherein the magnetic field generating means is equipped with magnetic field strength adjusting means for changing the strength of the magnetic field according to the characteristics of the processing gas. 4. A plasma processing apparatus using a permanent magnet as the magnetic field generating means, wherein the magnetic field strength adjusting means controls the position of the permanent magnet to approach an outer wall surface of the plasma processing chamber,
The plasma processing apparatus according to claim 3, wherein the plasma processing apparatus is configured to be movable in a direction of separating from each other. 5. The plasma processing apparatus according to claim 3, wherein in the plasma processing apparatus using a solenoid as the magnetic field generating means, the magnetic field strength adjusting means is configured to control the electric power supplied to the solenoid. .