JP2607832B2 - Microwave plasma processing method - Google Patents

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 method, and more particularly to a microwave plasma processing method suitable for manufacturing semiconductor devices and optical parts.

[0002]

2. Description of the Related Art A conventional apparatus is disclosed in JP-A-63-72123.
Publication No. JP-A-63-72124, a metal phase shifter is provided in a microwave waveguide, or a part of the waveguide is protruded to improve the processing speed. The processing unevenness is eliminated.

Further, as described in JP-A-63-73624, the plasma density is homogenized by adjusting the dielectric constant distribution of the bell jar corresponding to the surface to be processed of the sample, and the uniformity of the processing is improved. Had improved.

[0004]

In the above-mentioned prior art, the technology described in JP-A-63-72123 and JP-A-63-72124 does not take into account the objectivity of microwave propagation. Therefore, every time the processing conditions change, it is necessary to change the phase shifter and its equivalent.

In Japanese Patent Application Laid-Open No. 63-73624, although the symmetry is ensured, it is necessary to process the bell jar itself, and a change in the dielectric constant due to consumption of the bell jar during the processing cannot be guaranteed. There was a problem.

An object of the present invention is to provide a microwave plasma processing method capable of stably generating uniform gas plasma and improving processing uniformity.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to evacuate a plasma generation region, introduce a plasma processing gas into the plasma generation region, and oscillate a microwave to propagate in a waveguide. And generating a plasma by dividing the propagating microwave in the waveguide and introducing a stable uniform mode microwave into a plasma generation region, and processing the sample with the plasma. By doing so.

[0008]

The microwave oscillated by the microwave oscillating means propagates in the waveguide by the microwave propagating means.
The microwave being propagated is divided by the dividing means in the waveguide, and becomes a uniform mode microwave in the waveguide.
The gas for plasma processing is injected into the plasma generation region where the pressure is maintained at a predetermined pressure by the gas introduction unit and the vacuum exhaust unit, and the plasma processing gas is turned into plasma.
Thereby, the plasma for processing the sample is stably and uniformly generated, and the uniformity of the processing can be improved.

[0009]

An embodiment of the present invention will be described below with reference to FIG. In this case, as a microwave plasma processing apparatus for carrying out the present invention, a bell jar 5 is provided in a vacuum vessel in an airtight manner so as to cover a sample table 7 on which a sample 6 is placed. A vacuum exhaust device (not shown) is connected to the vacuum container, and a plurality of gas supply nozzles 8 are provided evenly so as to surround the sample table 7 toward the inside of the bell jar 5 . The outer periphery of the bell jar 5, the circular waveguide 4 is provided to surround the bell jar 5. In the circular waveguide 4, the cylinder 9 and the partition plate 1
The microwave composed of zeros is divided to form a uniform mode microwave , that is, the microwave is directly affected by the microwave electric field.
The cylinder 9 and the partition plate 10 are provided in
To a mode with a uniform electric field against the range of
And a phase shifter for generating a microwave . The cylinder 9 is supported in the circular waveguide 4 by a plurality of partition plates 10 arranged symmetrically so as to be arranged concentrically with the circular waveguide 4. The upper portion of the phase shifter of the circular waveguide 4 is formed in a tapered shape, and the rectangular waveguide 2 is connected to the opening end narrowed in the tapered shape via the conversion waveguide 3. 2
The magnetron 1 is attached to the end of the.

In the apparatus configured as described above, the plasma processing gas is introduced into the bell jar 5 by the gas supply nozzle 8, and is kept at a predetermined processing pressure by the vacuum exhaust device. The microwave is generated by the magnetron 1, propagates in the short waveguide 2, the conversion waveguide 3, and the circular waveguide 4, and is introduced into a bell jar 5 constituting a plasma generation chamber. A sample 6 and a sample stage 7 for holding the sample 6 are provided below the bell jar 5, and reaction products, unreacted gas, and the like in the plasma generation chamber are evacuated through a gap around the sample stage 7.

In this case, a phase shifter in which a metal cylinder 9 is fastened to each other by a plurality of partition plates 10 is formed in the circular waveguide 4, and the partition plates 10 are perpendicular to the microwave propagation direction. Are symmetrically installed including the cylinder 9 and the circular waveguide 4 in a simple plane. The number of the partition plates 10 is set according to the dimensions of the circular waveguide 4 and the cylinder 9 so that a uniform mode of microwaves is generated. Ie, circular waveguide
Sample 6 from microwave modes that can be generated in
Mode with a substantially uniform electric field facing the surface
To match the microwave electric field of the mode so that
And set the quantity at a position orthogonal to the electric field.
It is. Thereby, the cylinder 9 and the partition plate 10 are orthogonal to each other.
The microwave having an electric field that does not pass through the cylinder 9 and the partition plate 1
Cannot propagate in the space divided by 0,
Only the microwave having the mode of
Propagate. As a result, the microwave introduced into the circular waveguide 4 is split by the fixed phase shifter, becomes a uniform mode microwave, and enters the bell jar 5. This prevents the generation of microwaves in unnecessary modes.
Since the microwave in a uniform mode is always stably incident on the bell jar 5, a uniform plasma is formed in the plasma generation chamber, and a uniform plasma processing of the sample can be performed. As described above, the propagating microwave
Dividing within a waveguide means that space is divided into divided waveguides.
Introduces microwaves to separate cylinders and partitions that divide the space.
To propagate only microwaves with orthogonal electric fields.
That is, the electric field is divided by orthogonal members
Is done.

As described above, according to the present embodiment, a gas plasma capable of performing uniform plasma processing is generated using a microwave, that is, a phase shifter in which the mode of the microwave before entering the plasma generation chamber is fixed. Can be introduced into the plasma generation chamber by limiting to a uniform mode.
Stable uniform mode microwaves can be introduced into the plasma generation chamber, and uniform plasma is generated, preventing sample processing unevenness. In other words, it has the effect of improving processing uniformity, improving plasma processing productivity. it can. Although the present embodiment has been described using a cylinder and a circular waveguide, a short tube and a circular waveguide, a short tube and a short waveguide, or a combination of a cylinder and a short waveguide may be used. Needless to say, this is not a problem.

[0013]

According to the present invention, there is an effect that a uniform gas plasma can be generated stably and the uniformity of processing can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional perspective view showing an embodiment of a microwave plasma processing apparatus for carrying out the present invention.

[Explanation of symbols]

1: magnetron, 2: short waveguide, 3: conversion waveguide,
4: circular waveguide, 5: bell jar, 6: sample, 7: sample stage, 8: gas supply nozzle, 9: cylinder, 10: partition plate.

Claims (1)

(57) [Claims] A step of evacuating a plasma generation region;
A step of introducing a plasma processing gas into the plasma generation region, a step of oscillating microwaves and propagating in the waveguide, and a step of dividing the propagating microwaves in the waveguide to obtain a stable uniform mode microwave. A microwave plasma processing method, comprising: introducing a wave into the plasma generation region to generate plasma; and processing a sample by the plasma.