JPH07230897A - Microwave plasma processing device - Google Patents

Abstract

PURPOSE:To uniformly process a sample even if the sample or a sample stand is a circular shape in a plan view, and enhance utilization efficiency of microwave electric power. CONSTITUTION:Permanent magnets 31 are arranged on a side surface 10b sandwiching corner parts of a reactor vessel 10 so that different polarities N and S turn inside of the reactor vessel 10, and plasma can be uniformly generated in a reaction chamber 12, and a magnetic field can be also formed in the corner parts 10a of the.reactor vessel 10 being an almost rectangular solid shape. The plasma in the vicinity of the corner parts of the reaction chamber 12 can be pushed away inside of the reaction chamber 12 by this line 31a of magnetic force, and a plasma generating area of an almost circular shape in a plan view can be formed.

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 which is suitable for performing processing such as etching, ashing, and CVD on a semiconductor element substrate using plasma. Wave plasma processing apparatus.

[0002]

2. Description of the Related Art In an LSI manufacturing process, plasma generated when energy is externally applied to a reaction gas is widely used, and a dry etching technique using plasma is an indispensable basic technique.

Generally, RF (high frequency) of 13.56 MHz is used as an excitation means for generating plasma. However, the use of microwave can obtain high-density plasma at low temperature and There are advantages such as simple configuration and operation. However, in the conventional plasma processing apparatus using microwaves, it is difficult to uniformly generate plasma in a large area, and thus it is difficult to uniformly process a semiconductor substrate having a large diameter.

In order to deal with this problem, as a microwave plasma processing apparatus capable of uniformly generating plasma in a large area, a method using a dielectric line proposed by the present applicant is known. (JP-A-62-56
No. 00, JP-A-62-99481). FIG. 5 is a vertical cross-sectional view schematically showing a conventional microwave plasma processing apparatus of this type, and 10 in the figure shows a reaction container having a substantially hollow rectangular parallelepiped shape. The entire reaction vessel 10 except the upper wall is formed of a metal such as Al, and the side wall has a double structure, and the inside of this has a cooling water passage 11 through which cooling water flows.
Has become. A reaction chamber 12 having a substantially rectangular parallelepiped shape is formed inside the cooling water passage 11, and an upper portion of the reaction chamber 12 is hermetically sealed by a heat-resistant plate 13, and the heat-resistant plate 13 does not transmit microwaves. It is made of quartz glass, Al ₂ O ₃ or the like, which is possible and has a small dielectric loss.
A sample stage 14 for mounting the sample S is arranged at a position facing the heat resistant plate 13 inside the reaction chamber 12, and an exhaust device (not shown) is connected to a lower wall of the reaction chamber 12. An exhaust port 15 is formed, and a gas supply pipe 16 for supplying a desired reaction gas into the reaction chamber 12 is connected to one side wall of the reaction chamber 12.

On the other hand, above the reaction vessel 10, there is disposed a dielectric line 20 formed into a substantially rectangular parallelepiped shape by using fluororesin, polyethylene, polystyrene or the like having a small dielectric loss, and outside the dielectric line 20. A covering the dielectric line 20
A lid 21 formed using a metal plate such as 1 is provided. A waveguide 22 is connected to the dielectric line 20,
A microwave oscillator 23 is connected to the waveguide 22, and the microwave oscillated from the microwave oscillator 23 is introduced into the dielectric line 20 via the waveguide 22.

When the surface of the sample S is subjected to etching treatment or the like by using the microwave plasma processing apparatus thus constructed, the sample S is first placed on the sample table 14 and then cooled in the cooling water passage 11. After circulating water and exhausting it from the exhaust port 15 to set the reaction chamber 12 to a required degree of vacuum, the reaction gas is supplied from the gas supply pipe 16. Then, the microwave is oscillated by the micro oscillator 23 and introduced into the dielectric line 20 through the waveguide 22. Then, an electric field is formed below the dielectric line 20, the formed electric field passes through the heat resistant plate 13, reaches the reaction chamber 12, and generates plasma, and the plasma is subjected to a treatment such as etching. It

[0007]

In the above-mentioned microwave plasma processing apparatus, in order to uniformly generate plasma, the reaction chamber 12 is considered in consideration of microwave propagation characteristics and the like.
Has a substantially rectangular parallelepiped shape. However, if the reaction chamber 12 has a substantially rectangular parallelepiped shape, plasma is also generated at the corners of the reaction chamber 12. Therefore, when the sample S is a circular Si wafer, the plasma at the corners of the reaction chamber 12 can be processed. There was a problem that it could not be directly involved and wasted.

The present invention has been made in view of the above problems, and it is possible to uniformly generate plasma and to eliminate the waste of plasma involved in the processing, thereby making effective use of plasma and uniform processing. It is an object of the present invention to provide a microwave plasma processing apparatus that can be designed.

[0009]

In order to achieve the above object, a microwave plasma processing apparatus according to the present invention is provided with a dielectric line for forming a microwave waveguide and a dielectric line so as to face the dielectric line. A microwave plasma processing apparatus provided with a metal reaction container provided with one end facing the dielectric line and sealed with a heat-resistant plate that transmits microwaves, and having a sample stage provided therein. The present invention is characterized in that permanent magnets are arranged on the side surfaces of the reaction vessel, which sandwich the corners, so that different polarities are directed to the inside of the reaction vessel.

[0010]

In the above microwave plasma processing apparatus, when the microwave propagates through the dielectric line, which usually has a substantially rectangular parallelepiped shape, an electric field is formed in the vertical direction with respect to the dielectric line. This electric field causes plasma to be generated below the heat-resistant plate in parallel with the dielectric line. Therefore, in order to uniformly generate the plasma in the upper part of the reaction chamber, the shape of the upper part of the reaction chamber is preferably a substantially rectangular parallelepiped shape. It will be.

On the other hand, a Si wafer which is a semiconductor element substrate is often used as a sample, and this Si wafer is usually circular. Therefore, in the conventional apparatus, of the plasma generated in the entire upper portion of the reaction chamber having a substantially rectangular parallelepiped shape, the plasma at the corners is extinguished at the inner wall of the reaction container or is exhausted as it is, and thus it is difficult to supply the Si wafer. Plasma is wasted.

However, according to the microwave plasma processing apparatus having the above-mentioned structure, since the permanent magnets are arranged on the side surfaces sandwiching the corners of the reaction container so that the different polarities are directed to the inside of the reaction container, the reaction chamber is placed inside the reaction chamber. Plasma can be generated uniformly, and a magnetic field can be formed at the corner of the reaction container, which is usually a substantially rectangular parallelepiped shape, and the magnetic field lines push the plasma near the corner of the reaction chamber to the inside of the reaction chamber. This means that the plasma generation region having a substantially circular shape in plan view can be formed. Therefore, even if the sample or the sample table has a circular shape in plan view, the sample can be uniformly processed, and the utilization efficiency of microwave power can be improved.

If the distance between the permanent magnets sandwiching the corners is set smaller than the distance between the permanent magnets disposed on one side surface of the reaction vessel, Since the plasma in the vicinity of the corner portion is easily pushed to the inside of the reaction chamber, uniform treatment and improved utilization efficiency can be further achieved.

[0014]

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 an embodiment of a microwave plasma processing apparatus according to the present invention, and 10 in the drawing shows a reaction vessel. A plurality of permanent magnets 31 are arranged near the upper portion of the side surface 10b of the reaction container 10. As shown in FIG. 2, the permanent magnets 31 have different polarities on the side surfaces 11b sandwiching the corner portion 10a of the reaction container 10. The N and S are arranged so as to face the inside of the reaction container 10.
The distance A between the permanent magnets 31 arranged with the corner portion 10a sandwiched therebetween is set to be smaller than the distance B between the permanent magnets 31 arranged on the one side surface 10b of the reaction vessel 10.
Other configurations are the same as those shown in FIG. 4, and therefore detailed description thereof is omitted here.

When the surface of the sample S is subjected to etching treatment or the like by using the microwave plasma processing apparatus thus constructed, the sample S is first placed on the sample table 14 and then cooled in the cooling water passage 11. After circulating water and exhausting it from the exhaust port 15 to set 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 micro oscillator 23 and introduced into the dielectric line 20 through the waveguide 22, and an electric field is formed below the dielectric line 20. Then, this electric field passes through the heat resistant plate 13 and generates plasma in the entire upper part of the reaction chamber 12. Then, the magnetic force lines 31a and 31b generated between the permanent magnets 31 are formed.
(FIG. 2), the plasma is pushed to the inside of the reaction chamber 12 by the magnetic force lines 31a in the vicinity of the corner 10a (FIG. 2),
The plasma generation region 32 (FIG. 2) has a substantially circular shape in plan view, and the surface of the sample S is subjected to a treatment such as etching by the plasma from the plasma generation region 32.

The results of measuring the ion current density of the generated plasma using the microwave plasma processing apparatus according to the embodiment will be described below. The measurement conditions are shown in Table 1 below. Further, as a comparative example, the apparatus shown in FIG. 1 in which the permanent magnet 31 is not provided was used and an experiment was conducted under the same conditions.

[0017]

[Table 1]

FIG. 3 shows the plasma generation region in the Z direction (FIG. 1).
4 is a curve diagram showing an ion current density distribution in relation to each other, and FIG. 4 is a curve diagram showing an ion current density distribution in a diagonal direction connecting the corner portions 10a.
Curve B shows the case of the comparative example. As is apparent from these figures, the average ion current density was 13 mA / cm ² in the case of the comparative example in which the permanent magnet 31 was not provided, but in the case of the example in which the permanent magnet 31 was provided, Is 1
It was as high as 6 mA / cm ² .

As is clear from the above description and measurement results, in the microwave plasma processing apparatus according to the embodiment,
Sides 10b sandwiching a corner 10a (Fig. 2) of the reaction vessel 10
In addition, since the permanent magnets 31 are disposed so that the different polarities N and S are directed to the inside of the reaction container 10, plasma can be uniformly generated in the reaction chamber 12 having a substantially rectangular parallelepiped shape, and at the same time, A magnetic field can be formed in the corner portion 10a, and the magnetic field lines 31a (FIG. 2) cause the reaction chamber 12 to move.
Plasma in the vicinity of the corners of the plasma can be pushed to the inside of the reaction chamber 12, and the plasma generation region 32 is substantially circular in plan view.
(FIG. 2) can be formed. Therefore, even if the sample S or the sample table 14 has a circular shape in plan view, the sample S can be uniformly processed, and the utilization efficiency of microwave power can be improved.

In the embodiment, the side surface 10 of the reaction vessel 10 is
In comparison with the distance B between the permanent magnets 31 arranged in b, the distance A between the permanent magnets 31 arranged so as to sandwich the corner portion 10a is set to be small, but in another embodiment, Distance A
And the distance B may be the same, or the distance A may be set larger than the distance B.

In the embodiment, the permanent magnet 31 is provided near the upper portion of the side surface 10b of the reaction vessel 10, but in another embodiment, the range from the upper portion of the side surface 10b of the reaction vessel 10 to the vicinity of the intermediate portion. The permanent magnet 31 may be disposed in the.

Although the reaction vessel 10 is made of Al in the embodiment, it may be made of stainless steel in another embodiment.

[0023]

As described above in detail, in the microwave plasma processing apparatus according to the present invention, the permanent magnets are provided on the side surfaces of the reaction vessel sandwiching the corners so that different polarities are directed to the inside of the reaction vessel. Since it is arranged, a plasma can be generated uniformly in the reaction chamber, and a magnetic field can be formed at the corner portion of the reaction container, which is usually a substantially rectangular parallelepiped shape. Plasma in the vicinity of the part can be pushed inside the reaction chamber,
It is possible to form a plasma generation region having a substantially circular shape in plan view. Therefore, even if the sample or the sample stage has a circular shape in plan view, the sample can be uniformly processed and the utilization efficiency of microwave power can be improved.

[Brief description of drawings]

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

FIG. 2 is a horizontal sectional view schematically showing a microwave plasma processing apparatus according to an embodiment.

FIG. 3 is a curve diagram showing an ion current density distribution in the plasma region in the Z direction, where curve A shows the case of the example and curve B shows the case of the comparative example.

FIG. 4 is a curve diagram showing an ion current density distribution in a diagonal direction connecting the corners 10a of the plasma region, where curve A shows the case of the example and curve B shows the case of the comparative example.

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

[Explanation of symbols]

 10 Reaction container 10b Side surface 13 Heat-resistant plate 14 Sample stage 20 Dielectric line 31 Permanent magnet

Claims (1)

[Claims] 1. A dielectric line for forming a microwave waveguide, and a heat-resistant plate which is arranged so as to face the dielectric line and has one end facing the dielectric line and which transmits microwaves. In a microwave plasma processing apparatus provided with a reaction container made of metal, which is stopped and provided with a sample table inside, in a side surface sandwiching the corner of the reaction container, different polarities are directed to the inside of the reaction container. A microwave plasma processing apparatus comprising a permanent magnet.