JPH06151092A - Microwave plasma treatment device - Google Patents

Abstract

PURPOSE:To provide a microwave plasma treatment device capable of uniformly treating a sample, enhancing the utilizing efficiency of microwave power, and easily generating a plasma even under a low pressure. CONSTITUTION:In a microwave plasma treatment device having a microwave oscillator 24, a waveguide 23 for transmitting a microwave; a dielectric line 20, and a reactor 10 having a microwave guide window 13 arranged opposite to the dielectric line 20, a magnet 31 is arranged around the reactor 10. According to this constitution, since the permanent magnet 31 is arranged around the reactor 10, a magnetic field can be formed near a reaction chamber wall 12a to prevent the contact or collision of a plasma to the reaction chamber wall 12a, and the overall reduction or uneven distribution of the energy and density of the plasma can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave plasma processing apparatus, and more particularly to a microwave plasma processing apparatus used as an etching apparatus for a semiconductor element substrate or the like, a thin film forming processing apparatus, or the like.

[0002]

2. Description of the Related Art In the manufacturing process of LSI, various processes are often performed by using plasma.
Especially dry etching technology using plasma
It has become a basic technology indispensable to the manufacturing process.

Plasma is generated by externally applying energy to the reaction gas. As the main plasma excitation means, the case of using microwaves and the case of RF (Radio
Frequency) may be used. Compared to the case of using RF, the advantage of using microwave is as follows.
(1) High-density plasma can be obtained at a lower temperature, (2)
There are no pollutions due to electrodeless discharge, and (3) the device configuration and its operation are simple. However, the conventional plasma processing apparatus using microwave as the excitation means also has the following drawbacks. That is, (1) the plasma generation region is small, (2) it is difficult to uniformly generate plasma, and (3) it is difficult to uniformly process a large-diameter semiconductor substrate.

As a device having a wide plasma generation region and capable of uniformly generating microwave plasma,
A method using a dielectric line is disclosed (Japanese Patent Laid-Open Nos. 62-5600 and 62-99481). FIG. 5 is a vertical cross-sectional view schematically showing this type of microwave plasma processing apparatus, and 10 in the figure shows a hollow rectangular parallelepiped reactor. The reactor 10 is formed using a metal such as stainless steel or aluminum, and the peripheral wall of the reactor 10 has a double structure, inside which a cooling water passage 11 through which cooling water flows is formed. Passage 11
A reaction chamber 12 is formed inside the. The upper portion of the reactor 10 is hermetically sealed by a microwave introduction window 13, and the microwave introduction window 13 has a small dielectric loss and is a dielectric plate such as quartz glass or alumina having heat resistance and microwave transparency. Is formed by using. In the reaction chamber 12, a sample S is placed at a position facing the microwave introduction window 13.
Is provided with a sample table 14 for mounting the
An exhaust port 15 connected to an exhaust device (not shown) is formed on the lower wall or side wall of the reactor 10, and a gas supply pipe for supplying a required reaction gas into the reaction chamber 12 is provided on one side wall of the reactor 10. 16 are connected.

On the other hand, the dielectric line 2 is provided above the reactor 10.
0 is arranged, and the dielectric line 20 is formed using fluororesin, polyethylene, polystyrene, or the like, which has a small dielectric loss. A frame body 21 is provided on the upper surface and the outer peripheral portion of the dielectric line 20, and the frame body 21 is formed into a rectangular parallelepiped lid shape using a metal plate such as aluminum. Further, a waveguide 23 is connected to the dielectric line 20, and a microwave oscillator 24 is connected to the waveguide 23, and the microwave oscillated from the microwave oscillator 24 is introduced into the dielectric line 20. It is like this.

When the surface of the sample S mounted on the sample table 14 is etched using the microwave plasma processing apparatus having the above-described structure, first, the cooling water is circulated in the cooling water passage 11, Next, after exhausting from the exhaust port 15 to set the inside of the reaction chamber 12 to a required degree of vacuum, the reaction gas is supplied from the gas supply pipe 16. Next, the microwave is oscillated by the microwave oscillator 24, and the waveguide 23
It is introduced into the dielectric line 20 via. Then, an electric field is formed below the dielectric line 20, the formed electric field passes through the microwave introduction window 13 and is supplied into the reaction chamber 12 to generate plasma, and the generated plasma is guided to the surface of the sample S. Then, the surface of the sample S is etched.

[0007]

In the microwave plasma processing apparatus described above, there is a problem that when the generated plasma comes into contact with the side wall of the reaction chamber 12, a part of the plasma disappears. There was a problem that the energy and density distribution became non-uniform, the uniform treatment of the sample S was hindered, and the plasma energy and density were lowered overall, and the utilization efficiency of microwave power was low.

The present invention has been made in view of the above problems, and can prevent the plasma from coming into contact with the side wall of the reaction chamber, while the plasma is sufficiently diffused in the confined plasma generation region. It is possible to prevent the plasma energy and density from being lowered as a whole or to have a non-uniform distribution, so that the sample can be uniformly processed, and the microwave power utilization efficiency can be improved. It is an object of the present invention to provide a microwave plasma processing apparatus capable of increasing the temperature.

[0009]

In order to achieve the above object, a microwave plasma processing apparatus according to the present invention comprises a microwave oscillator, a waveguide for transmitting microwaves, and a waveguide connected to the microwave oscillator. In a microwave plasma processing apparatus comprising a dielectric line and a reactor having a microwave introduction window arranged opposite to the dielectric line, a magnet is arranged around the reactor. There is.

[0010]

The plasma generated in the reaction chamber diffuses, and a part of the plasma also diffuses near the wall of the reaction chamber. When the plasma diffuses near the wall of the reaction chamber, the charged particles recombine and collide with the wall of the reaction chamber, resulting in loss of plasma energy and reduction of plasma density.

As a result of many experiments conducted by the present inventor, as shown in FIG.
When 1 is provided, a magnetic field is formed along the wall surface of the reaction chamber 12, and this magnetic field prevents the plasma from coming into contact with or colliding with the reaction chamber wall 12a, and the plasma is generated at a predetermined distance from the reaction chamber wall 12a. It was found that the plasma generation region 32 as shown by the diagonal lines in FIG. Further, it has been found that the magnetic field in this case has an effect only in the vicinity of the reaction chamber wall 12a, and the plasma can easily diffuse in the plasma generation region 32.

According to the microwave plasma processing apparatus of the present invention, since the magnet is arranged around the reactor,
A magnetic field is formed in the vicinity of the wall of the reaction chamber, plasma is prevented from contacting or colliding with the wall of the reaction chamber, and the energy and density of the plasma are prevented from being lowered and the plasma is prevented from becoming nonuniform. Therefore, the sample S is uniformly processed, the utilization efficiency of microwave power is improved, and plasma can be easily generated at a low pressure.

[0013]

EXAMPLES AND COMPARATIVE EXAMPLES Examples of a microwave plasma processing apparatus according to the present invention will be described below with reference to the drawings. It should be noted that components having the same functions as those of the conventional example are designated by the same reference numerals. FIG. 1 is a vertical sectional view schematically showing the microwave plasma processing apparatus according to the present embodiment.
2 is a sectional view taken along the line AA ′ of FIG. However, since the configuration of the apparatus shown in FIGS. 1 and 2 is the same as that of the conventional microwave plasma processing apparatus shown in FIG. 5 except for the magnet 31, detailed description thereof is omitted here. The configuration will be described only for the points different from the above.

Reference numeral 10 in the drawing shows a reactor having a substantially hollow rectangular parallelepiped shape. The reactor 10 is made of a paramagnetic material such as stainless steel or aluminum.
A permanent magnet 31 having a magnetic flux density of about 2000 G is disposed around 0, and the permanent magnet 31 is 1 of the rectangular parallelepiped reactor 10.
Twelve pieces are attached to each side, and a total of twelve pieces are attached at substantially equal intervals. Further, the cross-sectional shape of the reaction chamber 12 has a length L of 300 mm and a width W of 300 mm. When the microwave plasma processing apparatus configured as described above is used and, for example, the surface of the sample S mounted on the sample table 14 is subjected to etching processing, the sample is subjected to a procedure similar to the procedure described in the section of the prior art. The S surface is etched.

In the following, the microwave plasma processing apparatus according to the embodiment is used, Ar is used as a reaction gas, and the pressure is 10
The result of measuring the ion current density of the generated plasma by setting mTorr will be described. In addition, the measurement point is set at a predetermined height on the sample table 14 with the center of the reaction chamber 12, that is, the plasma generation region 32 as the 0 (ZERO) point, and measured in the microwave traveling direction Z and the horizontal direction Y perpendicular thereto. Moved the points and did each. As a comparative example, an experiment was conducted under the same conditions using a device in which the permanent magnet 31 was not provided.

FIG. 3 is a graph showing the ion current density distribution of the plasma generation region 32 in the Y direction, and FIG. 4 is a graph showing the ion current density distribution of the plasma generation region 32 in the Z direction. As is clear from these figures, in the case of the embodiment in which the permanent magnet 31 is provided, the average ion current density is 24 mA / cm ² , the uniformity is ± 5%, and the permanent magnet 31 is provided. In the case of the non-comparative example, the average ion current density was 19 mA / cm ² and the uniformity was ± 10%. Therefore, it was confirmed that when the permanent magnet 31 is provided, a large ion current can be obtained and high-density plasma can be generated.

When an electromagnetic coil is provided as the magnet 31 instead of a permanent magnet, a strong magnetic field is formed even in the center of the reaction chamber 12, and plasma may be restricted by the magnetic field and diffusion may become difficult. At the same time, the device becomes larger. Therefore, it is preferable to use a permanent magnet for the magnet 31.

As is clear from these results, in the microwave plasma processing apparatus according to this embodiment, the permanent magnet 31 is arranged around the reactor 10, so that the reaction chamber wall 12 is provided.
A magnetic field can be formed in the vicinity of a, plasma can be prevented from coming into contact with or colliding with the wall of the reaction chamber 12a, and the energy and density of plasma can be reduced as a whole, or a non-uniform distribution can be achieved. Can be suppressed. Therefore, the sample S can be uniformly processed, the utilization efficiency of microwave power can be improved, and plasma can be easily generated even at a low pressure.

[0019]

As described in detail above, in the microwave plasma processing apparatus according to the present invention, since the magnet is arranged around the reactor, it is possible to form a magnetic field near the wall of the reaction chamber. Therefore, it is possible to prevent the plasma from coming into contact with or colliding with the reaction chamber wall, and it is possible to prevent the energy and the density of the plasma from being lowered as a whole and the uneven distribution. Therefore, the sample S can be uniformly processed, the utilization efficiency of microwave power can be improved, and plasma can be easily generated even at a low pressure.

[Brief description of drawings]

FIG. 1 is a vertical sectional view schematically showing a microwave plasma processing apparatus according to an embodiment of the present invention.

FIG. 2 is a horizontal cross-sectional view schematically showing a plasma generation region formed by a magnetic field of magnets arranged around the reactor in the microwave plasma processing apparatus according to the example.

FIG. 3 is a graph showing an ion current density distribution in the Y direction of a plasma generation region.

FIG. 4 is a graph showing an ion current density distribution in the Z direction of a plasma generation region.

FIG. 5 is a vertical sectional view schematically showing a conventional microwave plasma processing apparatus.

[Explanation of symbols]

 10 Reactor 13 Microwave Introducing Window 20 Dielectric Line 23 Waveguide 24 Microwave Oscillator 31 Magnet

Claims (1)

[Claims] 1. A reactor having a microwave oscillator, a waveguide for transmitting microwaves, a dielectric line connected to the waveguide, and a microwave introduction window arranged to face the dielectric line. A microwave plasma processing apparatus including: a microwave plasma processing apparatus, wherein a magnet is arranged around the reactor.