JP2627526B2 - Plasma generator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma generation apparatus that generates plasma by microwaves supplied from a microwave oscillator via a waveguide system in a plasma generation container.

[Conventional technology]

Plasma generators generate plasma in a low-pressure gas to form a thin film of plasma polymerization on the surface of a sample,
This device is used for plasma treatment of the surface.It is used for improving the adhesive strength of polymer materials, dyeing, improving hygroscopicity, and modifying the metal surface. And contribute to lowering the temperature of the process.

FIG. 5 shows the structure of an example of this type of conventional plasma generator.

In the figure, 1 is a plasma generating vessel having a quartz tube 11 as a main body, 12 is a gas introduction pipe, 13 is an exhaust pipe, 14 is a sample table, 18 is a vacuum gauge, 21 is a microwave oscillator, 22 is an isolator, and 23 is power A monitor, 24 is a stub tuner (matching element), 25 is an applicator, 26 is a variable short circuit, 30 is a sample, and 40 is a plasma generation region.

The microwave oscillated by the microwave oscillator 21 is guided to the applicator 25 via a waveguide system such as an isolator 22, a power monitor 23, and a stub tuner 24.

The microwave oscillator 21 is blocked by the isolator 22 so that the microwave reflected from the applicator 25 does not return. The power monitor 23 detects the incident power P _i and the reflected power P _γ.
Can be monitored, and the microwave can be matched by adjusting the stub insertion depth of the stub tuner 24.

The applicator 25 is formed such that a hole is formed at the center position of the H plane of the rectangular waveguide, that is, the maximum position of the electric field, and the quartz tube 11 passing through the hole is perpendicular to the H plane.

By introducing a gas from the gas introduction pipe 12 and discharging the gas from the exhaust pipe 13, a low-pressure gas flows in the quartz tube 11, and the variable short circuit device 26 is adjusted to generate plasma at the center position of the quartz tube 11. Then, the surface of the sample 30 placed on the sample stage 14 is subjected to plasma processing or a thin film is formed.

At this time, while monitoring the incident power _Pi and the reflected power _Pγ by the power monitor 23, the stub tuner 24 adjusts to a state where the microwave is efficiently used.

[Problems to be solved by the invention]

In a conventional microwave plasma generator, for example, when the microwave is in the 2450 MHz band, the thin film has a diameter of about
There is a problem that plasma is generated only in a 2.5 cm area, and the plasma generation area 40 is small.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problem, and has as its object to provide a plasma generator in which a thin film is generated in a wider area.

[Means for Solving the Problems] The plasma generating apparatus of the present invention includes a plasma generating container,
A microwave oscillator having a comb-shaped slow-wave circuit on an inner wall surface facing the surface of the sample stage, and a microwave supply hole at a position where microwaves from the microwave oscillator are supplied to the slow-wave circuit; From the microwave supply hole of the container through the waveguide system to the plasma generating container.

[Action]

With this configuration, the wavelength of microwaves is shortened, the pitch of the electric field is narrowed, the microwaves radiated directly into the gas are reduced, and most of the microwaves are slow wave circuits. , And is radiated into the gas, so that the microwave is transmitted over a wide area, and the plasma generation region is widened.

〔Example〕

 1 and 2 show the configuration of one embodiment of the present invention.

In the figure, 12, 13, 14, 30, and 40 indicate the same or corresponding parts as those shown by the same reference numerals in FIG. 5, 1a is a plasma generation vessel, 11a is a wall of the main body of the plasma generation vessel 1a, and 15 is Comb-shaped slow-wave circuit provided in a partial area of the inner wall surface, 16 is a microwave supply hole, 17 is a low-loss material for making the microwave supply hole 16 airtight, 27 is a waveguide, and 28 is a microwave. The branch hole 29 is a microwave supplier.

By introducing gas from the gas introduction pipe 12 and discharging the gas from the exhaust pipe 13, a low-pressure gas flows into the airtight area surrounded by the wall 11a.

On the other hand, the microwave oscillated by the microwave oscillator is guided to a waveguide 27 through a waveguide system such as an isolator, a power monitor, and a stub tuner, is branched into a microwave branch hole 28, and is supplied to a microwave supply unit 29. Through microwave supply hole
From 16 is supplied into the plasma generating vessel 1a.

The wavelength of the microwave supplied into the container 1a is shortened by the slow-wave circuit 15 and spread, the plasma is generated in a wide area 40, and a thin film is formed on a wide surface of the sample 30.

FIG. 3 shows an example of a comb-type slow wave circuit. The TM mode electromagnetic field distribution of this slow wave circuit is expressed by the following equation.

E _X = Aexp [-αy + j (ωt-βz)] ... (1) α is an attenuation constant, β is a phase constant, and β is obtained by the following equation.

l: tooth height, P: tooth pitch, b: tooth spacing, :frequency, μ _o = 4π × 10 ⁻⁷ [H / m] From equation (4), it can be seen that the value of β changes when the tooth height l, the pitch P, and the interval b are changed. When the value of β changes, the electromagnetic field distribution changes, and the state of plasma generation changes.

FIG. 4 shows an example of a slow wave circuit having different tooth heights and intervals depending on locations.

By decreasing b or increasing l, the wavelength shortening rate of the microwave can be increased. If the value of b is 1/20 of the free space wavelength, the wavelength is reduced to 1/10. In the case of = 2450 MHz, the wavelength can be 12.2 mm.

Increasing the number of the microwave supply holes 16 reduces the power of the microwave supplied from one supply hole, and has the advantage that the generation of sparks near the supply hole 16 is reduced.

1 and 2, four slow wave circuits are arranged in parallel,
Although an example is shown in which three microwave supply holes 16 are provided per row, these are not limited, and a configuration suitable for the purpose of use can be adopted.

〔The invention's effect〕

As described above, according to the present invention, there is an effect that a plasma generation region can be expanded and a thin film can be formed on a wide surface.

[Brief description of the drawings]

1 and 2 are explanatory diagrams showing the configuration of one embodiment of the present invention, FIG. 3 is an explanatory diagram showing an example of a comb-shaped slow wave circuit, and FIG. 4 is another example of a comb-shaped slow wave circuit. FIG. 5 is an explanatory view showing a configuration of an example of a conventional plasma generator of this type. 1a: Plasma generating container, 11a: Wall, 12: Gas introduction pipe, 13: Exhaust pipe, 14: Sample stage, 15: Comb-shaped slow wave circuit, 16: Microwave supply hole, 17 ... Low-loss material, 27... Waveguide, 28... Microwave branch hole, 29... Microwave supply device, 30... Sample, 40... Plasma generation region. In the drawings, the same reference numerals indicate the same or corresponding parts.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H01L 21/3065 H01L 21/302 A

Claims (2)

(57) [Claims] In a plasma generating apparatus for generating plasma by a microwave supplied from a microwave oscillator via a waveguide system in a plasma generating vessel, a gas introducing pipe for introducing a gas and discharging the gas are provided. And a sample stage for mounting a sample inside the sample stage, and a single row or a plurality of rows of comb-shaped microwave slow-wave circuits are provided on an inner wall facing the surface of the sample base. A plasma generating vessel provided with a microwave supply hole at each position where microwaves from the wave oscillator are supplied to the above-mentioned slow wave circuit, and microwaves from the microwave oscillator are guided to the microwave feeder through the waveguide system. A microwave supply system for supplying from the microwave supply device into the plasma generation container from the respective microwave supply holes of the plasma generation container. That the plasma generating device. 2. The plasma generator according to claim 1, wherein the size of the teeth of the slow-wave circuit and the distance between the teeth differ depending on the location.