JPH06333848A - Plasma generating device - Google Patents

Abstract

PURPOSE:To control the conditions of microwave incidence on plasma by a simple structure and provide plasma uniformity by covering the part of a plasma container with a microwave shielding wall and controlling the plasma distributing conditions in the plasma container by the position of the microwave shielding wall. CONSTITUTION:Microwave generated by a microwave generating source 8 is transmitted to an external container 10 through a waveguide 9, is directed into a plasma container which allows electromagnetic wave permeation so as to be absorbed by plasma on an ECR plane 14 and plasma is formed. When plasma density becomes high, the quantity of reflecting microwave becomes higher than the quantity absorbed. The reflecting microwave passes through a space 15 by repeating reflection between the external container and the microwave shielding wall 12. The ratio of the incidence quantity from the plasma container top plane 7 to the incidence quantity from the plasma container side plane 7a can be varied by permitting the microwave shielding wall 12 to be vertically movable, and plasma density distribution can be controlled.

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 equipped with a plasma generator, and more particularly to a plasma processing apparatus suitable for fine processing of semiconductor elements.

[0002]

2. Description of the Related Art Various inventions have been made to generate uniform and high density plasma in a dry etching apparatus and a chemical vapor deposition (CVD) apparatus using plasma. For example, in JP-A-3-229859, a rotating magnetic field is applied to homogenize the plasma, and in JP-A-2-139924, the magnetic field is also varied to homogenize the plasma. Further, in Japanese Patent Laid-Open No. 3-79771, an electrode is inserted into the plasma to make the plasma uniform. However, none of these controls how microwaves are incident on the plasma, and in particular, the conventional microwave plasma devices are those in which microwaves are incident only from one side of the ECR surface.

[0003]

In the existing plasma generator, the state of incidence of microwaves on the plasma is not controlled in order to apply the microwaves to the plasma as much as possible.

The above-mentioned prior art also controls the absorption distribution of microwaves by changing the magnetic field distribution in the plasma. At present, the mechanism for absorbing microwaves into the plasma is not completely understood, but the plasma is controlled. Is not enough for.

It is an object of the present invention to control the state of microwave incidence on plasma with a simple structure and realize uniform plasma.

[0006]

In order to achieve the above object, the present invention provides a plasma source, a plasma holding container for holding the plasma generated by the plasma source, a microwave source, and the plasma. In a plasma generation device comprising an outer container surrounding a holding container and enclosing the microwave generated by the microwave generation source inside, a part of the plasma holding container is covered with a microwave blocking wall, and depending on the position of the microwave blocking wall. Means are provided for controlling the distribution of plasma within the plasma container.

[0007]

The microwave generated by the microwave source is incident on the plasma holding container which transmits the electromagnetic wave. Since a part of the plasma holding container is covered with the microwave blocking wall, the microwave does not enter from the covering portion. If the microwave blocking wall is not fixed, the state of the microwave incident on the plasma holding container can be changed by changing its position. The reflected microwaves are reflected by an outer container surrounding the plasma holding container and enter the plasma holding container again.

Further, when the electron cyclotron (ECR) resonance is used, the electron cyclotron resonance surface (E
There is a CR side). Microwaves are absorbed near the ECR surface in plasma, but pass through the ECR surface in the atmosphere. Therefore, part of the microwave generated by the microwave generation source is directly incident on the plasma holding container and absorbed by the ECR surface, and part of the microwave is propagated between the microwave blocking wall and the outer container in the atmosphere, Once passing through the ECR surface, it is then incident on the plasma holding container and microwaves are introduced from the opposite direction to the ECR surface. A high-density plasma can be obtained by applying microwaves from both sides of the ECR surface, and the density distribution of the plasma can be controlled by adjusting the position of the microwave blocking wall.

[0009]

EXAMPLE FIG. 1 shows a microwave plasma etching apparatus as an example of a plasma processing apparatus.

A sample 2 to be etched is formed in the center of the apparatus.
Is installed on the sample table 3. The sample table also serves as an electrode, and a high-frequency bias current may be applied between the sample table and the ground electrode 11. The sample and the sample stage are installed inside a cylindrical plasma holding container 7 made of, for example, quartz. The plasma holding container has various shapes such as a hemispherical shape and a cylindrical shape. The processing chamber 1 inside the plasma holding container is connected to a gas introduction part 4 and a gas discharge part 5. The plasma holding container is further housed in an outer container 10, and a microwave generation source 8 is attached to the upper part of the outer container via a waveguide 9. A coil 6 is attached to the outside of the external container, and the ECR
Forming a surface.

Generated by the microwave source 8, for example,
The 2.45 GHz microwave propagates through the waveguide 9 and enters the outer container 10. Further, the microwave passes through the plasma holding container 7 that transmits the electromagnetic wave, enters the processing chamber, and is absorbed by the plasma in the vicinity of the ECR surface. The absorbed energy converts the etching gas flowing from the gas introducing portion toward the gas discharging portion into a plasma in the processing chamber, and the generated plasma further uses the etching gas as an active reactive species for etching.

Next, an embodiment of the present invention will be described with reference to FIG. FIG. 2 is an embodiment in which the present invention is applied to the microwave etching apparatus for processing a semiconductor wafer shown in FIG. 1, and is a sectional view of the apparatus. The operation of the device is basically as shown in FIG.
It is the same as the device.

In the apparatus shown in FIG. 2, the plasma holding container has a cylindrical shape, and the outer circumference thereof is covered with a microwave blocking wall 12. The microwave blocking wall may be a conductor tube or a conductor mesh tube. A wide gap 15 is provided between the plasma holding container 7 and the outer container 10. The microwave generated by the microwave generation source 8 travels through the waveguide 9 and enters the external container 10, and then enters the plasma holding container 7 that transmits electromagnetic waves, and is sucked into the plasma at the ECR surface 14 to generate plasma. . However, as the plasma density becomes higher, the amount of reflected microwaves becomes greater than the amount of absorbed microwaves. The reflected microwaves pass through the gap 15 while being repeatedly reflected between the outer container and the microwave blocking wall 12. Microwaves must pass through the ECR surface in the gap 15, but can easily pass because there is no plasma. The microwaves that have passed through the gap are re-incident from the portion 7a of the plasma holding container, strike the ECR surface from the side opposite to the microwaves that have entered from the portion 7 of the plasma holding container, and generate absorbed plasma. Since the microwaves are mainly absorbed in the vicinity of the ECR surface and the microwave incident side, the microwaves are incident from both sides of the ECR surface, so that the microwave absorption region is expanded and a high plasma density can be obtained. In addition, the microwave blocking wall 1
By making 2 variable up and down, the ratio of the incident amounts from the upper surface 7 and the side surface 7a of the plasma holding container can be changed, so that the plasma density distribution in the plasma holding container can be controlled.

FIG. 3 shows another embodiment in which the present invention is applied to a microwave etching apparatus. The basic operation principle is the same as that of the embodiment of FIG. 2, and the shape of the microwave blocking wall 12 is different from that of the embodiment of FIG. 2, and the width of the gap 15 is changed to change the amount of microwaves passing through the gap 15. The feature is that it can be adjusted.

FIG. 4 shows another embodiment in which the present invention is applied to a microwave etching apparatus. The basic operation principle is the same as that of the embodiment of FIG. 2, and the shape of the microwave blocking wall 12 is different from the embodiment of FIG. 2 and is a donut-shaped disk, so that the microwave blocking wall can be made very simple. Is characteristic.

FIG. 5 shows another embodiment in which the present invention is applied to a microwave etching apparatus. The basic operating principle is the same as that of the embodiment of FIG. 2, but in this embodiment, the microwave blocking wall 12a is also provided on the upper part of the plasma holding container. In the present embodiment, the microwave blocking wall 12a is fixed in a conical shape, but may be asymmetrical, or may be moving such as rotating. The microwave blocking wall reflects a part of the microwave that is directly incident on the plasma holding container 7 from the waveguide 9 and holds the reflected microwave through the gap 15 between the outer container 10 and the microwave blocking wall 12. It is made incident from the 7a portion of the container. Therefore, the amount of microwaves incident from above and below the ECR surface 14 can be adjusted by the shape of the microwave blocking wall 12a, and the plasma distribution in the plasma holding container can be adjusted.

[0017]

According to the present invention, since the incident state of microwaves on plasma can be adjusted with a simple structure, a uniform and high-density plasma can be obtained. Therefore, high-speed and highly uniform plasma treatment can be achieved. It can be carried out.

[Brief description of drawings]

FIG. 1 is a perspective view of a conventional microwave plasma etching apparatus.

FIG. 2 is a vertical sectional view of an embodiment of the present invention.

FIG. 3 is a vertical sectional view of another embodiment of the present invention.

FIG. 4 is a vertical sectional view of still another embodiment of the present invention.

FIG. 5 is a vertical cross-sectional view of still another embodiment of the present invention.

[Explanation of symbols]

1 ... Processing chamber, 2 ... Sample, 3 ... Sample stand, 6 ... Coil, 7 ...
Plasma holding container, 8 ... Microwave source, 9 ... Waveguide, 10 ... External container, 12 ... Microwave blocking wall, 13 ...
Gap, 14 ... ECR surface.

Claims (7)

[Claims] 1. A plasma generation source, a plasma holding container for holding plasma generated by the plasma generation source, a microwave generation source, and a microwave generated by the microwave generation source surrounding the plasma holding container. A plasma generating apparatus having an external container for enclosing the plasma in the plasma holding container, wherein a part of the plasma holding container is covered with a microwave blocking wall, and a plasma distribution state inside the plasma holding container is controlled by the position of the microwave blocking wall. A plasma generation device comprising: 2. The plasma generator according to claim 1, wherein the plasma holding container is made of quartz glass, and the microwave blocking wall is made of a conductor. 3. The plasma generating apparatus according to claim 1, wherein the plasma holding container is cylindrical, and the microwave blocking wall is concentrically arranged on a side surface of the cylindrical plasma holding container. 4. A plasma generator according to claim 2, which has the same features as in claim 3. 5. The magnetic field generation source according to claim 1, wherein the magnetic field generation source forms an ECR surface that is a uniform magnetic flux density surface of 875 Gauss in the inside of the plasma holding container, and the microwave blocking wall is the same. A plasma generation device arranged so that the microwave generated by the microwave generation source enters from both sides of the ECR surface. 6. A plasma generator according to claim 5, which has the features of claim 2. 7. A plasma generator according to claim 6, which has the features of claim 3.