JPH0673320B2 - Microwave plasma generator - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improvement of a microwave plasma generator.

(Prior Art) Low-temperature plasma generated by the discharge of low-pressure gas promotes various chemical reactions while the entire system is at low temperature.
It can be applied to both inorganic and organic materials and has a very wide range of applications, and is used for semiconductor manufacturing processes, polymer materials, surface modification of metals, and the like.

However, in order to generate this low-temperature plasma, the method of exciting by RF (13.56MHz) was mainly used in the conventional R & D / practical machines, but the use of microwave is more efficient and more efficient. It is known to be advantageous (Hirose: Microwave discharge plasma and its equipment, coating technology, 1
9, [1], (1980), pages 100-105). The advantages are shown below.

The ratio Te / Tg of the electron temperature Te and the gas temperature Tg is large, and a lower temperature plasma can be obtained.

High density plasma can be generated.

Since no electrode is required, contamination from the electrode can be prevented.

The oscillator structure is simple.

Since microwaves are transmitted using a waveguide, there is no radiation loss and the structure can be easily matched.

By the way, many microwave plasma generators conventionally used have a structure in which a quartz tube is penetrated into a waveguide to generate plasma in the quartz tube.

However, in the case of such a structure, since the plasma generation part is limited by the size of the waveguide, a large amount of samples or large samples cannot be processed. Further, with this structure, since microwaves are vertically incident on the plasma, the microwaves are largely reflected by the plasma and the plasma is likely to be nonuniform.

On the other hand, a microwave plasma generator (RGBosisio, CFWeissfloch, M.
R. Wertheimer: The Large Volume Microwave Plasma Gen
erator, J. Microwave Power, 7 (4), P325-346, 1972)
Can generate a relatively large volume of plasma, but the structure becomes complicated.

Therefore, the applicant of the present invention has filed a patent application for a microwave plasma generator using a dielectric-coated line capable of stably generating a large-area and non-uniform plasma using microwaves with a relatively simple structure. No. 143036 and Japanese Patent Application No. 60-240
Proposed in No. 070. FIG. 2 shows a schematic configuration of the microwave plasma generator previously proposed by the applicant.

In FIG. 2, reference numeral 1 denotes a microwave oscillator, and the microwave generated from the microwave oscillator is transmitted by the waveguide 2.

Reference numeral 3 is a dielectric that is in communication with the waveguide 2, and a reaction container 5 having a closed structure having a quartz glass plate 4 as a ceiling wall surface is disposed below the dielectric.

In addition, 6 is a gas introduction device provided with the gas cylinder 7 and the flowmeter 8, and 9 is an exhaust device.

(Problems to be Solved by the Invention) By using the microwave plasma generator having the above-described structure, it is possible to generate uniform plasma over a wide area with a relatively simple structure.

However, since the dielectric covered line formed by the dielectric 3 and the region where plasma is generated, that is, the reaction container 5 are separated, plasma is generated using an electric field exponentially attenuated from the dielectric surface. It was Therefore, there is an inherent problem that the utilization efficiency of microwave power is poor.

The present invention has been made in view of the above circumstances, and similar to the device previously proposed by the applicant, a microwave is used to generate a large-area and uniform plasma, and the efficiency of use of power and the throughput are improved. It is intended to provide a microwave plasma generator capable of achieving the above.

(Means for Solving the Problems) The present invention relates to a microwave oscillator, a waveguide for transmitting microwaves from the microwave oscillator, and a dielectric for communicating with the waveguide to form a dielectric covered line. And a reaction container which is placed in communication with the dielectric and has a gas introduction device and an exhaust device. The dielectric is disposed so as to divide the reaction container into two parts, and the reaction container It is a microwave plasma generator characterized in that it has a resonator structure for surface waves on a dielectric covered line.

(Operation) A microwave plasma generation device according to the present invention includes a microwave oscillator, a waveguide that transmits microwaves from the microwave oscillator, and a dielectric that forms a dielectric covered line that is connected to the waveguide. And a reaction container which is placed in communication with the dielectric and has a gas introduction device and an exhaust device. The dielectric is disposed so as to divide the reaction container into two parts, and the reaction container Since it is a resonator structure for the surface wave on the dielectric covered line, it is possible to generate plasma on both sides of the dielectric and use the microwave propagating through the dielectric directly for plasma generation. it can.

(Example) The present invention will be described below based on an example shown in FIG. The same reference numerals as those in FIG. 2 in FIG. 1 indicate the same or corresponding portions, and detailed description thereof will be omitted.

In the apparatus of the present invention, a dielectric 3 such as quartz glass, Pyrex glass, or alumina is erected at approximately the center of the metal reaction container 5 to divide the reaction container 5 into two parts, left and right. Then, the waveguide 2 is installed to introduce the microwave from the side surface of the dielectric 3.

With such a configuration, the dielectric 3 serves as a microwave waveguide, and an electric field is applied to the left and right rooms A and B divided by the dielectric 3.

By the way, the length of the dielectric 3 in the microwave traveling direction is m times (m: an integer) the wavelength λ / 2 of the surface wave of the dielectric 3, and the reaction container 5 has a resonator structure. In this embodiment, in order to reduce the reflection of microwaves at the connecting portion with the waveguide 2, the formation of the dielectric 3 at the connecting portion is the first.
The taper shape is used as shown in FIG.

The chambers A and B on the left and right of the reaction vessel 5 in the microwave plasma generator according to the present invention configured as described above are evacuated, respectively, and the gas is introduced into the chambers A and B under a low pressure. When microwaves are introduced into the body 3, plasma can be generated in the two chambers A and B from the dielectric 3.

Next, a specific example will be described.

Use microwaves with a frequency of 2.45 GHz and use dielectric 3
Thickness: 20 mm, width (w): 200 mm, length (l): 44 in the central part of the reaction vessel 5 so as to form a resonator structure for the surface wave of
A 0 mm quartz glass plate was installed.

Using the apparatus having such a configuration, the reaction vessel 5 is evacuated,
SiH ₄ and N ₂ gas were introduced. And the microwave oscillator 1
Further, when microwaves are introduced into the dielectric covered line, plasma is generated substantially uniformly in both chambers A and B in the reaction vessel 5 along the quartz glass plate, and the SiN film is also deposited substantially uniformly on the Si wafer 10. .

The apparatus of the present invention can be applied to the epitaxial growth, the production of amorphous Si, the formation of an organic polymer film using an organic monomer, etc., in addition to the above-mentioned embodiments.

(Effects of the Invention) As described above, the microwave plasma generation device according to the present invention includes a microwave oscillator, a waveguide for transmitting microwaves from the microwave oscillator, and a dielectric that is connected to the waveguide. It comprises a dielectric body forming a body-covered line and a reaction vessel connected to the dielectric body and provided with a gas introduction device and an exhaust device, the dielectric body being arranged so as to divide the reaction vessel into two parts. At the same time, since the reaction vessel is a resonator structure for surface waves on the dielectric covered line,
Plasma can be generated on both sides of the dielectric, and the microwave propagating through the dielectric can be used directly for plasma generation. Therefore, the use efficiency of electric power is improved, and a large number of processes can be performed at one time.

[Brief description of drawings]

FIG. 1 is an explanatory view of a main part of the device of the present invention, (a) is a plan view showing a cross section, (b) is a sectional view taken along the line (a), and FIG. 2 is a schematic explanatory view of a conventional device. is there. 2 is a waveguide, 3 is a dielectric, and 5 is a reaction vessel.

Claims (1)

[Claims] 1. A microwave oscillator, a waveguide for transmitting microwaves from the microwave oscillator, a dielectric that is in communication with the waveguide to form a dielectric-coated line, and is disposed in communication with the dielectric. A reaction vessel provided with a gas introduction device and an exhaust device, wherein the dielectric is arranged so as to divide the reaction vessel into two parts, and the reaction vessel is provided with a surface wave on a dielectric covered line. On the other hand, a microwave plasma generator characterized by having a resonator structure.