JP2649914B2 - Microwave plasma generator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a microwave plasma generator, and more particularly to a microwave plasma generator used for a plasma CVD method and a plasma etching method using microwaves.

[Description of Prior Art]

In recent years, in plasma CVD and plasma etching, a method of generating plasma using microwave energy has been proposed and put to practical use.

For example, a plasma CVD method using a microwave (hereinafter, referred to as “MW-PCVD method”) is a semiconductor device, a photosensitive device for electrophotography, a line sensor for image input, an imaging device, a photovoltaic device, and others. It has been put to practical use as a method for forming a functional deposited film as an element member used for various electronic elements, optical elements, and the like.

Specifically, for example, when an amorphous silicon deposition film is formed on a substrate, a microwave is introduced into a vacuum vessel into which a source gas such as a silane gas or a hydrogen gas has been introduced, and the vacuum vessel is activated by microwave energy. Is dissociated to generate neutral radical particles, ionic particles, electrons, and the like, and these are alternately reacted to form an amorphous silicon deposited film on the surface of the substrate.

And conventionally, this kind of plasma using microwave
A microwave plasma generator used for the CVD method or the plasma etching method typically has an apparatus configuration shown in the schematic diagram of FIG.

In FIG. 3, 1 is a microwave generator such as a magnetron, 2 is a circulator, 3 is a non-reflection load, 4 is a microwave detector, 5 is a tuner, 6 is a plasma generation chamber, 7 is a gas inlet, 8 is an air core coil, 9 is a sample to be processed, 10 is a sample holder, and 11 is an exhaust system.

The generation of microwave plasma by such a device is performed as follows. In other words, the microwave of a frequency of 2.45 GHz generally used is the microwave generator 1
Using a circulator 2 and a non-reflective load 3,
The reflected microwave is supplied to the plasma generation chamber 6 through the tuner while preventing the reflected wave of the microwave from returning to the microwave generation source 1. In order to promote ionization, a magnetic field is applied to the plasma generating chamber 6 by an air-core coil 8 so as to cause electron cyclotron resonance, a processing gas is introduced through a gas inlet 7, and a proper pressure is maintained by an exhaust system 11. And generate plasma. The generated plasma is supplied to the sample 9 placed on the sample holding table 10, and predetermined processing is performed.

However, when microwaves are applied using the microwave plasma generator having the above configuration, most of the supplied microwave power is reflected because no plasma is present in the plasma generation chamber 6 in the initial state, and the microwave power is supplied to the microwave generator 1 side. Where the light is reflected. Therefore, when the pressure in the plasma generation chamber is 10 ⁻³ Torr or less, plasma is hardly generated,
It is necessary to increase the pressure of the plasma generation chamber in the initial state. That is, there is a problem that it is difficult to keep the pressure of the plasma generation chamber in a steady state.

[Object of the invention]

The present invention overcomes the above-mentioned problems in the microwave plasma generator and makes it possible to form a deposited film by the microwave plasma CVD method and perform etching using the microwave plasma constantly and efficiently. It is intended to provide a device.

That is, the main object of the present invention is to perform a stable deposition film formation by a microwave CVD method and an etching using a microwave plasma from an initial state by using an auxiliary microwave generator in a microwave plasma generator. It is an object of the present invention to provide a device which enables the above.

[Configuration of the invention]

The inventor of the present invention has conducted intensive studies to achieve the object of the present invention, and has found that the problem in the conventional microwave plasma generator can be solved by using an auxiliary microwave plasma generator. .

The present invention has been completed based on this finding. The present invention is a microwave plasma generator that supplies a microwave generated from a microwave generator to a plasma generation chamber and generates plasma in the plasma generation chamber,
The present invention relates to a microwave plasma generator having an auxiliary plasma generator for supplying plasma into the plasma generation chamber using microwaves reflected from the plasma generation chamber.

 Hereinafter, the apparatus of the present invention will be described in detail with reference to the drawings.

FIG. 1 schematically shows an apparatus according to an embodiment of the present invention. In the figure, 1 is a microwave generator such as a magnetron, 2 is a circulator, 31 is a non-reflection load, 4 is a microwave detector, 5 is a tuner, 6 is a plasma generation chamber, 8
Is an air-core coil, 9 is a sample to be processed, 10 is a sample holder, 11 is an exhaust system, 12 is an auxiliary plasma generator, 21 is a circulator, 41 is a microwave detector, 51 is a tuner including an attenuator, 71 is gas. Each entry is shown.

In the apparatus shown in FIG. 1, when microwave power is supplied from the microwave generator 1 to the plasma generation chamber 6 via the circulator 2, the microwave detector 4, and the tuner 5, the plasma is not supplied in the initial state. Most of the generated microwave power is reflected to the microwave generator 1 side. The reflected microwave enters the circulator 21 by the circulator 2. Here, the circulator 21 functions as a microwave supply unit for supplying the microwave entering the circulator 21 to the auxiliary plasma generator 12. That is, the traveling direction of the microwave entering the circulator 21 is defined, and then the microwave detector 41, a tuner and an attenuator for attenuating the microwave and adjusting the microwave supplied to the auxiliary plasma generation chamber 12 are provided. It is supplied to the auxiliary plasma generator 12 via 51. When a microwave reflected on the circulator 21 side is generated by the auxiliary plasma generator 12, the microwave is attenuated by the tuner and the attenuator 51.
The direction in which the light enters the circulator 21 through 41 is defined, and is absorbed by the non-reflective load 31.

FIG. 2 is a schematic diagram showing details of the auxiliary plasma generator 12, in which FIG. 13 is a microwave supply coaxial cable, 14 is an antenna, 15 is a plasma generation chamber, 16 is an orifice, and 81 is an orifice. Each of the permanent magnets is shown.

In the auxiliary plasma generator shown in FIG. 2, microwaves are supplied to an antenna 14 by a coaxial cable 13,
A microwave electric field is generated in the plasma generation chamber 15. A magnetic field (875 Gauss when microwave frequency is 2.45 GHz) generated by the permanent magnet 81 is applied to the plasma generation chamber 15 by the permanent magnet 81, and the interaction between the electric field of the microwave and the magnetic field effectively increases the magnetic field. Plasma is generated. The raw material gas or the processing gas supplied into the plasma generation chamber 15 is supplied from the gas inlet 71, and the inside of the plasma generation chamber 15 is maintained at about 1 × 10 ^{-2 to} 1 Torr, which is a pressure at which plasma is easily generated. The exhaust conductance is appropriately adjusted by the orifice 16. The plasma containing charged particles generated in the plasma generation chamber 15 has an orifice
The plasma particles 16 are supplied to the main plasma generation chamber 6, and plasma is generated in the main plasma generation section 6 using the charged particles as seeds. Similarly, the reflected microwaves from the main plasma generation chamber are drastically reduced.
The microwave supplied to 12 decreases, and the plasma in the plasma generation chamber 15 of the device 12 disappears.

When the plasma is generated in the plasma generation chamber 6 and the plasma becomes unstable for some reason and disappears, and the reflected microwaves increase again, the plasma is generated in the auxiliary plasma generator 12 in the same manner as described above. Auxiliary operation can be automatically performed by generating plasma in the main plasma generation chamber 6 using the plasma as a seed.

Although the auxiliary plasma generator shown in FIG. 1 uses a coaxial cable and an antenna, a waveguide may be used for supplying microwaves. The use of an antenna can be eliminated by using a body resonator. Further, the plasma generation chamber can be covered with quartz, alumina, or the like to prevent contamination of metal or the like. Further, similar effects can be obtained by using an electromagnet such as an air-core coil instead of the permanent magnet as the magnetic field generating means.

〔The invention's effect〕

The apparatus of the present invention facilitates the generation of plasma by using an auxiliary microwave generator using reflected microwaves, and the plasma generation auxiliary operation can be automatically performed by the feedback configuration.

[Brief description of the drawings]

FIG. 1 is a schematic view schematically showing an embodiment of the present invention, and FIG. 2 is a schematic view showing details of the auxiliary plasma generating apparatus of the present invention. FIG. 3 is a schematic diagram of a conventional apparatus. Regarding the figure, 1 ... microwave generator, 2 ... circulator, 3
… Non-reflective load, 4… Microwave detector, 5… Tuner, 6… Plasma generation chamber, 7… Gas inlet, 8
... air-core coil, 9 ... sample to be processed, 10 ... sample holder, 11 ... exhaust system, 12 ... auxiliary plasma generator, 13 ...
… Microwave supply coaxial cable, 14 …… Antenna, 15
... plasma generation chamber, 16 ... orifice, 21 ... circulator, 31 ... non-reflective load, 41 ... microwave detector, 51 ... tuner and attenuator, 71 ... gas inlet,
81 ... permanent magnet

Claims (3)

(57) [Claims] 1. A microwave plasma generator for supplying a microwave generated from a microwave generator to a plasma generation chamber (A) to generate plasma in the plasma generation chamber (A), A microwave plasma generator comprising an auxiliary plasma generator for supplying plasma into the plasma generation chamber (A) using microwaves reflected from the chamber. 2. The plasma generating chamber according to claim 2, wherein the auxiliary plasma generating apparatus is different from the plasma generating chamber (A).
Claims: It has a microwave supply means for supplying microwaves reflected from the plasma generation chamber (A), and a gas introduction means for supplying gas into the plasma generation chamber (B). Item 2. The microwave plasma generator according to Item 1. 3. The microwave plasma generator according to claim 2, wherein said gas introduction means communicates with said plasma generation chamber (A) through said auxiliary plasma generator.