JPH07114998A - Plasma generator - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize high-density plasma in a plasma generator used for CVD (chemical vapor deposition), etching, an ion source, and the like. [Structure] The gas inlet 11 is connected to a high-speed valve 12, and the orifice 13 of the high-speed valve 12 is attached to a quartz glass cylinder 14. The tip of the cylinder 14 is connected to a vacuum chamber 15 having an exhaust port 16. The opening time of the high speed valve 12 is 0.5 ms
ec, the repetition rate is set to 60 Hz, and a supersonic flow gas is ejected from the orifice 13 into the vacuum chamber 15. A rectangular waveguide 17 is provided between the high speed valve 12 and the vacuum chamber 15 so as to surround the cylinder 14. The cylinder 14 is inserted into the center of the widthwise surface of the waveguide 17, and the protrusions 22 are provided on both sides of the cylinder 14 on the longitudinal surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to CVD (chemical vapor deposition),
The present invention relates to a plasma generator for processing used for etching, an ion source and the like.

[0002]

2. Description of the Related Art Conventionally, as a plasma generator, for example, a microwave exciter manufactured by EWIG is known. Hereinafter, based on this, a conventional plasma generator will be described.

FIG. 4 is a sectional view of a conventional microwave plasma generator. In FIG. 4, 1 is 96 mm inside
27 mm rectangular waveguide, 2 is a quartz glass cylinder having an outer diameter of 40 mm and an inner diameter of 36 mm inserted in the center of the longitudinal surface of the waveguide 1, and 3 is for adjusting the impedance of the waveguide 1. It is a plunger.

In the plasma generator having the above structure, 1 Torr is filled by introducing argon gas into the cylinder 2 from the Y ₁ direction and exhausting it in the Y ₂ direction, and a microwave of 2.45 GHz, 100 W is applied. Waveguide 1
It is introduced from the X direction. Then, by moving the plunger 3 to bring the place where the electric field of the microwave becomes strong to the cylinder 2, the argon plasma 4 is generated inside the cylinder 2.

[0005]

However, in the above-mentioned conventional plasma generator, when the plasma diffused in the Y ₂ direction is used, the excited state is lowered due to collision with residual gas. There was a point.

In order to solve the above-mentioned problems of the prior art, it is an object of the present invention to provide a plasma generator having a high density of ions or excitons of diffusion plasma.

[0007]

In order to achieve the above object, the first structure of the plasma generator according to the present invention comprises a high-speed valve for introducing a gas for generating a shock wave, and a high-speed valve before the high-speed valve. At least the attached dielectric cylinder, a vacuum chamber connected to the cylinder and provided with at least an exhaust port, and a microwave radiation means provided around the cylinder between the high-speed valve and the vacuum chamber. Be prepared.

In the first construction, it is preferable that the high speed valve is opened and closed by an electromagnetic valve, and in this case, it is preferable that the high speed valve is operated by a pulse voltage or an AC voltage.

Further, in the first construction, it is preferable that the outlet of the high speed valve is composed of a nozzle and a skimmer. Further, in the first configuration, it is preferable that the dielectric tube is made of quartz glass, Pyrex glass, or boron nitride.

Further, in the first structure, the microwave is preferably 2.45 GHz. Further, in the first configuration, it is preferable that the microwave radiating means is a rectangular waveguide. In this case, a dielectric tube is further inserted in the center of the rectangular waveguide, and protrusions are formed on both sides. It is preferably provided.

In the first structure, it is preferable that the velocity of the gas blown out from the high speed valve is equal to or higher than the sonic velocity. A second configuration of the plasma generator according to the present invention is a plurality of high-speed valves for introducing a gas for generating a shock wave, a dielectric cylinder attached to the tip of the high-speed valve, and the cylinder. And a microwave chamber provided around the cylinder between the high-speed valve and the vacuum chamber, and at least a vacuum chamber provided with at least a reactive gas inlet and an exhaust port. is there.

[0012]

According to the first structure, the microwave
Shock wave generated by gas discharged from a high-speed valve
Can be further heated by 10¹²cm
^-3The above high-density plasma can be generated.

Further, in the first structure, according to a preferable structure in which the outlet of the high speed valve is composed of the nozzle and the skimmer, the shock wave generating gas can be discharged as a supersonic pulse beam.

In the first structure, the microwave radiating means is a rectangular waveguide, a dielectric tube is inserted in the center of the rectangular waveguide, and projections are provided on both sides. , The characteristic impedance of the rectangular waveguide becomes low, and matching to the cylindrical plasma becomes easy.

Further, according to the second structure, the reaction product can be formed on the large-area substrate at a high speed.
Productivity can be improved.

[0016]

EXAMPLES The present invention will be described in more detail below with reference to examples. (Embodiment 1) FIG. 1 is a sectional view showing an embodiment of a plasma generator according to the present invention, and FIG. 2 is a sectional view of a waveguide in an embodiment of a plasma generator according to the present invention.

In FIGS. 1 and 2, 11 is a gas inlet, and the gas inlet 11 is connected to a high speed valve 12.
Here, the orifice 13 of the high speed valve 12 has an outer diameter of 28 m.
It is attached to a quartz glass cylinder 14 having a diameter of m and an inner diameter of 25 mm. The high-speed valve 12 is a system that opens and closes by an electromagnetic valve, and the diameter of the orifice 13 is 0.5 mm. The tip of the cylinder 14 is connected to a vacuum chamber 15, and the vacuum chamber 15 is provided with an exhaust port 16. Exhaust port 16
A turbo molecular pump (not shown) is attached to the pump and the pumping speed is about 500 l / sec. The high-speed valve 12 is connected to a power source 23. For example, if the opening time is 0.5 msec and the repetition rate is 60 Hz, the velocity of the gas ejected from the orifice 13 becomes several tens of times the sonic velocity, and the inside of the vacuum chamber 15 is increased. Can be ejected as a supersonic flow.

Further, between the high speed valve 12 and the vacuum chamber 15, the cylinder 14 is surrounded so that 109.2 mm × 5.
A 4.6 mm rectangular waveguide 17 is provided. A magnetron 18 is provided at one end of the waveguide 17, and a plunger 19 for adjusting the impedance of the waveguide 17 is provided at the other end. A circulator 20 and a stub 21 are provided between the magnetron 18 and the cylinder 14. The cylinder 14 is inserted in the center of the widthwise surface of the waveguide 17, and projections 22 are provided on both sides of the cylinder 14 on the longitudinal surface. As a result, the characteristic impedance is lowered, and matching with a cylindrical plasma is facilitated. In addition, in FIG. 1 and FIG.
24 is a non-reflection termination.

In the plasma generator having the above-mentioned structure, first, when, for example, 5 atmospheres of argon gas is introduced from the introduction port 11 in the X direction, the argon gas is ejected from the orifice 13 as a supersonic flow. At this time, a microwave of 2.45 GHz and 300 W from the magnetron 18 is introduced into the waveguide 17, and the plunger 19 and the stub 21 are adjusted so that a standing wave stands inside the waveguide 17 and the electric field strength is increased. Bringing the strong part into the cylinder 14 causes the discharge of argon by microwaves. The impedance inside the waveguide 17 changes depending on whether plasma is present or not, but this can be dealt with by adjusting the stub 21, and the reflected wave is separated by the circulator 20 and the non-reflection termination is performed. Guided to 24. At this time, the gas pressure in the vacuum chamber 15 is several tens Torr.
And the atom ejected from the orifice 13 and the vacuum chamber 15
Atom-atom collisions occur with the atoms remaining inside to heat the atoms, and the electrons in the atoms gain energy by the collisions and cause cumulative ionization. Then, electronic-
Shock wave plasma heating that ionizes the atoms occurs due to the inelastic collision of the atoms. High-density plasma can be generated in the vacuum chamber 15 by the action of the base plasma by the microwave and the plasma heating by the shock wave. Incidentally, when the plasma density was measured by the Langmuir probe method, it was 10 ¹² cm ^-3 or more.

In the first embodiment, the pulse voltage is used to operate the high speed valve 32. However, the present invention is not limited to this, and the same effect can be obtained even with an AC voltage. You can

Although quartz glass is used as the material of the cylinder 14 in the first embodiment, the material is not necessarily limited to this and any dielectric material may be used. In particular,
In addition to quartz glass, Pyrex glass or boron nitride is preferable.

(Embodiment 2) FIG. 3 is a sectional view showing another embodiment of the plasma generator according to the present invention. The difference from the first embodiment is that a plurality of high speed valves are arranged.

In FIG. 3, reference numeral 31 is an inert gas inlet, and the inert gas inlet 31 is connected to a high speed valve 32. The outlet of the high-speed valve 32 is composed of a nozzle 33 and a skimmer 34. From the general law of aerodynamics, for example, the L. Valyi ATOM AND IO
N SOURCES (JOHN WILEY & SO
NS Publishing, London, 1977), p. According to the design of 91, the atoms that have passed through the skimmer 34 are supersonic, and have sufficient velocity and directionality to form a beam. The high-speed valve 32 is an electromagnetic valve that opens and closes.
The nozzle 33 is a cone of 30 degrees and has a diameter of 0.3 mm and a length of 0.6.
The skimmer 34 is a conical tube having an inner inclination of 25 degrees and an outer inclination of 35 degrees, and has an opening diameter of 0.6 mm. In addition, the skimmer 34 includes
Is provided at a position separated by 2.6 mm from the tip of the.

The high speed valve 32 has an outer diameter of 28 mm and an inner diameter of 25 m.
It is attached to a quartz glass cylinder 35 of m. The tip of each cylinder 35 is connected to a vacuum chamber 36, and the vacuum chamber 36 is provided with a reactive gas introduction port 37 and an exhaust port 38. A turbo molecular pump (not shown) is provided at the exhaust port 38.
Is installed and the pumping speed is about 1000 l / se
c. Further, between the high speed valve 32 and the vacuum chamber 36,
109.2 mm × 54. So as to surround the cylinder 35.
A 6 mm rectangular waveguide 39 is provided. Here, the cylinder 35 is inserted in the center of the surface of the waveguide 39 in the width direction. In FIG. 3, 40 is a glass substrate and 41 is a heating means.

In the plasma generator having the above-mentioned structure, for example, argon gas is introduced at 5 atm from each inert gas inlet 31 in the X direction. And the high speed valve 32
When the opening time is 0.5 msec and the repetition rate is 30 Hz, the velocity of the gas ejected from the orifice 33 is several tens of times the sonic velocity, and the gas is ejected into the vacuum chamber 34 as a supersonic flow. At this time, if, for example, monosilane gas (SiH ₄ ) is introduced from the reactive gas introduction port 37 in the Y direction so that the pressure in the vacuum chamber 36 becomes 10 Torr, the skimmer 34
Atom-atom collision occurs between the atom ejected from the atom and the atom remaining in the vacuum chamber 36 to heat the atom, and the electron in the atom obtains energy by this collision to cause cumulative ionization. Thereafter, shock wave plasma heating that ionizes the atoms occurs due to inelastic electron-atom collisions. still,
In order to smoothly perform the initial discharge by the shock wave, a microwave of 2.45 GHz is introduced into the waveguide 39 to generate a base plasma of argon. In the mixed gas plasma of monosilane and argon thus generated, only the argon gas flows through the high speed valve 32, so that the corrosion due to the monosilane gas can be suppressed.
Here, the glass means 40 is heated to 300 by the heating means 41.
When heated to ° C, amorphous silicon is deposited on the glass substrate 40. As described above, in the plasma generator according to the second embodiment, the plurality of high-speed valves 32 are arranged, so that amorphous silicon can be formed on a large-area substrate at high speed, resulting in high productivity. It is possible to improve.

[0026]

As described above, according to the first configuration of the plasma generator of the present invention, the base plasma generated by the microwave can be further heated by the shock wave generated by the gas emitted from the high speed valve. 10 ¹² c
It is possible to generate high density plasma of m ⁻³ or more.

Further, in the first structure, according to the preferable structure in which the outlet of the high speed valve is composed of the nozzle and the skimmer, the shock wave generating gas can be emitted as a supersonic pulse beam.

In the first structure, the microwave radiating means is a rectangular waveguide, a dielectric tube is inserted in the center of the rectangular waveguide, and protrusions are provided on both sides. , The characteristic impedance of the rectangular waveguide becomes low, and matching to the cylindrical plasma becomes easy.

Further, according to the second structure, since the reaction product can be formed on the large-area substrate at a high speed,
Productivity can be improved. Therefore, according to the present invention, for example, a plasma having a number of excellent effects such as generation of high-purity and high-density plasma from a mixed gas of monosilane / argon, and high-speed formation of amorphous silicon on a quartz substrate. A generator can be realized.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a plasma generator according to the present invention.

FIG. 2 is a cross-sectional view of a waveguide in one embodiment of the plasma generator according to the present invention.

FIG. 3 is a sectional view showing another embodiment of the plasma generator according to the present invention.

FIG. 4 is a cross-sectional view showing a plasma generator according to a conventional technique.

[Explanation of symbols]

 11 Gas Inlet 12, 32 High Speed Valve 13 Orifice 14, 35 Cylinder 15, 36 Vacuum Chamber 16 Exhaust 17, 17 Rectangular Waveguide 18 Magnetron 19 Plunger 20 Circulator 21 Stub 22 Protrusion 23 Power Supply 24 Non-Reflective Termination 31 Inert Gas inlet port 33 Nozzle 34 Skimmer 37 Reactive gas inlet port 38 Exhaust port 40 Glass substrate 41 Heating means

Claims (13)

[Claims] 1. A high-speed valve for introducing a gas for generating a shock wave, a dielectric cylinder attached to the tip of the high-speed valve, a vacuum chamber connected to the cylinder and provided with at least an exhaust port. A plasma generator comprising at least a microwave radiating means provided around a cylinder between the high-speed valve and the vacuum chamber. 2. The plasma generator according to claim 1, wherein the high speed valve is opened and closed by an electromagnetic valve. 3. The plasma generator according to claim 2, wherein the high speed valve is operated by a pulse voltage. 4. The plasma generator according to claim 2, wherein the high speed valve is operated by an AC voltage. 5. The plasma generator according to claim 1, wherein the outlet of the high speed valve comprises a nozzle and a skimmer. 6. The dielectric cylinder is quartz glass.
The plasma generator described in 1. 7. The plasma generator according to claim 1, wherein the dielectric cylinder is Pyrex glass. 8. The dielectric cylinder is boron nitride.
The plasma generator described in 1. 9. The plasma generator according to claim 1, wherein the microwave is 2.45 GHz. 10. The plasma generator according to claim 1, wherein the microwave radiating means is a rectangular waveguide. 11. The plasma generator according to claim 10, wherein a dielectric tube is inserted in the center of the rectangular waveguide, and projections are provided on both sides. 12. The plasma generator according to claim 1, wherein the velocity of the gas blown out from the high speed valve is equal to or higher than the speed of sound. 13. A plurality of high-speed valves for introducing a shock wave-generating gas, a dielectric cylinder attached to the tip of the high-speed valve, and a reactive gas inlet and exhaust connected to the cylinder. A plasma generator comprising at least a vacuum chamber having at least a mouth and a microwave radiating means provided around a cylinder between the high-speed valve and the vacuum chamber.