JP2552140B2 - Plasma generation reactor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention, in the fields of electronics, chemical industry, etc., makes a reaction gas into plasma under a relatively low vacuum and brings it into contact with a solid surface (substrate) or the like. The present invention relates to a plasma generation reaction device for forming a thin film or the like, and more particularly to a plasma generation reaction device capable of forming a uniform wide range carbon thin film.

[Prior Art] Conventionally, as a plasma generation reaction device of this type, for example, there is one shown in FIG. The microwave oscillated by the microwave oscillator 1 propagates in the rectangular waveguide 3 through the isolator 2 and reaches the applicator 4. Reference numeral 5 is an absorber for absorbing reflected waves, and 6 is a stub tuner for impedance matching. A quartz pipe 7 is inserted into the applicator 4, and a substrate holder 8 is provided at the intersection of the applicator 4 and the rectangular waveguide 3. Reference numeral 9 is a variable short-circuiting plate for generating a standing wave at the crossing portion thereof, and a substrate 10 as a base material for forming a thin film or the like is placed on the substrate holder 8. Reference numeral 11 denotes a quartz pipe and a holder of a holding table, which are attached to the lower end of the quartz pipe 7, and one end of which is connected to an exhaust pump, whereby the inside of the quartz pipe 7 is depressurized. The reaction gas and the carrier gas are injected into the inside of the quartz pipe 7 from above.

As another plasma generation reaction device, for example, as shown in FIG. 12, a cylindrical or rectangular resonator 21 for introducing microwaves from an inlet 21a, and a variable short-circuit plate 22 provided in the opposite direction of the inlet 21a, A substrate holder 24 on which the substrate 23 should be placed,
Some have a bell jar 25 that is provided in the resonator 21 and holds a vacuum.

[Problems to be Solved] However, the above-described conventional plasma generation reaction device has the following problems.

In the former plasma generation reactor, the substrate 10 is located near the end of the rectangular waveguide 3, and the distance between the center of the substrate 10 and the variable short-circuit plate 9 is (1/4 + n / 2) of the guide wavelength. The plasma is generated around the substrate 10 after being adjusted to double, but the energy intensity of that portion is determined by the mode of the rectangular waveguide 3,
As shown in FIG. 11, since the energy intensity in the applicator 4 is proportional to the square of the electric field E, the central portion of the substrate 10 is strong,
The surrounding area has a sharply attenuated distribution. Therefore, the central part of plasma is also intensively strong, and the surroundings are weak,
The thin film, crystal, etc. formed in the central part of the substrate 10 is thick, and the periphery thereof is thin, non-uniform thin film, crystal, etc. are formed, and the generation area is small.

Especially, microwave output: 200 ~ 600W, frequency: 2450Μ H _Z ,
Deposition time: 6 to 10 hours, gas: mixed gas of methane and hydrogen (20 to 50 torr) and the ratio of methane to hydrogen is 0.5 to 1.5
%, Long side of waveguide a = 109.2mm, short side of waveguide b = 54.6m
m, applicator diameter c = 54.0 mm, diameter is about 20 m
A carbon-based thin film is deposited in a narrow range of m.

In the latter plasma generation reaction device, the plasma region 26 is locally generated in the vicinity of the side of the bell jar 25, which is closer to the intake 21a than the substrate 23, so that the thin film formed on the substrate 23 becomes non-uniform.

This is because when a carbon-based thin film is formed, plasma is generated under a low vacuum of 20 to 50 torr.

[Object of the Invention] The present invention is to solve the above-mentioned problems, and an object thereof is to provide a plasma generation reaction device capable of forming a uniform thin film, crystal or the like in a wide range.

[Means for solving problems]

In order to achieve the above object, the present invention is to introduce a microwave into a mixed gas of hydrogen gas and an organic compound that decomposes and produces carbon by plasma, and a carbon-based thin film on the surface of an object on a holding table in an applicator. In the plasma generation reactor for generating crystals, a TE _11n resonance mode cylindrical resonator or a TE _m0n resonance mode rectangular resonator having a plurality of microwave inlets is used as the applicator, and each microwave inlet is used. Is provided with a phase shifter capable of interlocking with each other.

[Action]

According to the present invention, since a plurality of microwave inlets are provided in the cylindrical resonator or the rectangular resonator, a strong electric field region of a predetermined mode can be formed, and a single wide area or a plurality of dispersed plasma areas can be formed. Can be generated. Furthermore, since a phase shifter that can be interlocked with each other is provided for each microwave inlet, it is possible to reliably generate a strong electric field region of a predetermined mode and move the position of the strong electric field region. Can be made. As a result, it becomes possible to match the spatial relationship between the generated plasma region of a single wide range or a plurality of dispersed regions and the substrate, and it is possible to generate a thin film, crystal, etc. of a uniform wide range.

[Embodiment] Next, an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a first diagram of a plasma generation reaction device according to the present invention.
It is a block diagram which shows an Example.

In FIG. 1, 31 is a single microwave oscillator such as a magnetron, which has an isolator 3 having a wave absorber 32a.
2 is connected. The isolator 32 is necessary to absorb the reflected wave and stably oscillate the microwave oscillator 31. Reference numeral 33 is a T-shaped branch pipe which divides the microwave into two. The waveguide system branched into two systems is connected to opposite microwave inlets 34a and 34b of the applicator 34, and a waveguide between the T-shaped branch pipe 33 and the microwave inlet 34a. The system has a power monitor 35a for monitoring incident power and reflected power and a stub tuner 36a as an impedance matching device, and a waveguide between another T-shaped branch pipe 33 and a microwave inlet 34b. The system is also provided with a power monitor 35b and a stub tuner 36b.

The microwave oscillated by the single microwave oscillator 31 is divided into two systems by the T-shaped branch pipe 33 via the isolator 32 and supplied to the microwave inlets 34a and 34b, respectively.
As the applicator 34, for example, a cylindrical resonator shown in FIG.
40 is used.

The cylindrical resonator 40 as the applicator 34 has a cylindrical conductor 41.
A closed conductor 42a, 42b having microwave inlets 34a, 34b opposed to each other in the axial direction and closing both ends of the cylindrical conductor 41, a lower cylindrical body 43 and an upper cylindrical body 44 orthogonally penetrating the cylindrical conductor 41, A lower plunger 46 in a lower cylindrical body 43 that supports a vacuum-holding quartz tube 45 that should pass through the cylindrical conductor 41 at right angles, and a cylindrical conductor
The upper plunger 47 in the upper cylinder 44 that closes 41 and the substrate
A substrate holder 49 that can move vertically and rotate on which 48 should be placed,
A gas introduction pipe 50 for introducing a gas into the quartz tube 45 on the rotation center line of the substrate holding base 49, an exhaust pipe 51 connected to an exhaust pump communicating with a gap along the shaft of the substrate holding base 49, and a cylinder. conductor
A water cooling tube 52 wound around 41 and the like, and an internal observation window 53 for observing a plasma region generated in the quartz tube 45 are provided. In addition, 54 is a packing, 55 is an O-ring, and 56 is a choke.

Microwaves are introduced into the cylindrical resonator 40 from both of them via axially opposed microwave inlets 34a and 34b, where the axial length of the resonator is l and the diameter is D.
As shown in FIG. 7, the inside is in a resonance state of the TE ₁₁₃ resonance mode. As a result, a relatively wide range of plasma region is generated in the cylindrical resonator 40. It was confirmed that the plasma was brought into more contact with the surface of the substrate 48 by adjusting the substrate holder 49 so that the electric field E and the surface of the substrate 48 were orthogonal to each other.

FIG. 6 shows another cylindrical resonator 60 used as the applicator 34. This cylindrical resonator 60 includes a cylindrical conductor 61,
Closed conductors 62a, 62b having microwave inlets 34a, 34b opposed to each other in the axial direction and closing both ends of a cylindrical conductor 61, and a quartz plate 63a as a partition for holding vacuum instead of the quartz tube 45 shown in FIG.
63b, a substrate holder 64 that can move up and down and on which the substrate 48 should be placed, and a quartz plate 63a on the rotation center line of the substrate holder 64,
The gas introduction pipe 65 for introducing gas into the 63b and the substrate holding table 6
An exhaust pipe 66 connected to an exhaust pump and communicating with a gap along the shaft of 4, a water cooling pipe 67 wound around a cylindrical conductor 61, and an internal observation window 68 for observing a generated plasma region. I have. Note that 69 and 70 are Ο rings.

The cylindrical resonator 60 also resonates in the TE ₁₁₃ mode shown in FIG. 7, and a plasma region covering the surface of the substrate 48 is generated. As a result, a thin film having a uniform and wide range is formed on the surface of the substrate 48.

FIG. 8 shows a rectangular resonator 80 used as the applicator 34. This rectangular resonator 80 has a length l, a long side a, and a short side b.
A rectangular conductor 81 having microwave inlets 34a, 34b opposed to each other in the longitudinal direction, a lower plunger 83 supporting a bell jar 82 in the rectangular conductor 81, and a vertically movable and rotatable substrate on which a substrate 48 should be placed. A holding base 84, a bell jar 82 having a gas introduction pipe 82a on the rotation center line of the substrate holding base 84, an exhaust pipe 85 communicating with a gap along the shaft of the substrate holding base 84 and connected to an exhaust pump, and a rectangular conductor. And a water cooling pipe 86 wound around 81 or the like. Note that 87 and 88 are Ο rings.

The rectangular resonator 80 resonates in the TE _mon mode by the microwaves introduced from opposite directions of the microwave inlets 34a and 34b. Therefore, in TE _mon mode, the substrate 48
Since there is no electric field of the surface tangent component of the plasma, the plasma makes more contact with the surface of the substrate 48. For example, as shown in FIG. 9, in the case of TE ₂₀₁ mode resonance, the theoretical resonance wavelength λ ₀ is Given in.

However, in the state where the substrate 48 is inserted, the wavelength is shortened due to its dielectric constant, and the microwaves are injected from both ends, so that mutual interference occurs, so that the resonance wavelength λ ₀ is slightly changed. Finally, the optimum dimensions of the rectangular resonator 80 are experimentally set. The same applies to the case of the cylindrical resonators 40 and 60.

FIG. 2 shows a second part of the plasma generation reaction device according to the present invention.
It is a block diagram which shows an Example. The same parts as those shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

The second embodiment relates to an improvement of the first embodiment, in which each branch waveguide system has a circulator 37a (37b) and a variable short circuit 38a (38).
b) is provided with a phase shifter 39a (39b). Both variable short-circuit devices 38a, 38b are interlocked, and the electric length of each branch waveguide system up to the microwave inlets 34a, 34b is changed by adjusting the variable short-circuit plate, and the microwave inlets 34a, 34b are
The coupling state of the microwaves injected into the applicator 34 via b changes, the resonance state, that is, the plasma generation range or generation region can be controlled relatively freely, and the resonator 40 as the applicator 34 can be controlled. The size of 60, 60, 80 can be designed relatively roughly, and various substrates can be
Optimal adjustment of the plasma generation state is also realized by the difference in dielectric constant of 48.

FIG. 3 is a third view of the plasma generation reaction device according to the present invention.
It is a block diagram which shows an Example. The same parts as those shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

The plasma generation reactor of the third embodiment is a dedicated microwave oscillator 31a corresponding to each microwave inlet 34a (34b).
(31b), and this microwave oscillator 31a (31b
b) isolators 32'a (32'b) with absorbers
Is connected.

According to this device, a plurality of microwave oscillators 31a, 31
Due to the presence of b, high-power microwaves can be injected into the applicator 34, and the plasma generation region can be expanded. Further, although microwaves are injected into the applicator 34 in opposite directions, interference can be reduced by selecting the frequencies of the microwave sources to be significantly different, and mutually independent resonance states can be obtained. As a result, it is easier to control the expansion and uniformity of plasma generation.

FIG. 4 is a fourth diagram of the plasma generation reaction device according to the present invention.
It is a block diagram which shows an Example. The same parts as those shown in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted.

The fourth embodiment relates to the improvement of the third embodiment, and a circulator 37'a (37'b) and a variable short circuit 38'a are provided in each waveguide system.
(38'b) is provided with a phase shifter 39'a (39'b), and the variable short-circuit devices 38'a and 38'b are interlocked with each other. The electrical length of the waveguide system up to the inlets 34a, 34b is variable, and thereby the plasma generation range or generation region can be controlled relatively freely.

In each of the above embodiments, the resonator has two microwave inlets 34a and 34b, but the present invention is not limited to this, and a resonator having three or more microwave inlets is used as the applicator. It goes without saying that it can be used.

[Effects of the Invention] As described above, according to the present invention, a plurality of microwave inlets are used as applicators in a plasma generation reaction apparatus that plasmaizes a reaction gas under a relatively low vacuum to generate a carbon-based thin film or the like. Since it has a TE _11n resonance mode cylindrical resonator or a TE _m0n resonance mode rectangular resonator, it has a feature in that a phase shifter that can interlock with each other is provided at each microwave inlet. , It has the following unique effects.

That is, when forming the strong electric field region of the predetermined resonance mode in the cylindrical resonator or the rectangular resonator, the predetermined resonance mode can be surely generated by adjusting the phase shifters in conjunction with each other. , The position of the strong electric field region can be moved. As a result, it is possible to match the spatial relationship between the generated plasma region having a single wide range or a plurality of dispersed distributions and the substrate. Can be generated.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a plasma generation reaction device according to the present invention. FIG. 2 is a configuration diagram showing a second embodiment of the plasma generation reaction device according to the present invention. FIG. 3 is a block diagram showing a third embodiment of the plasma generation reaction device according to the present invention. FIG. 4 is a block diagram showing a fourth embodiment of the plasma generation reaction device according to the present invention. FIG. 5 (A) is a vertical cross-sectional view showing a cylindrical resonator used in each example, and FIG. 5 (B) is a side view schematically showing the cylindrical resonator. FIG. 6 (A) is a longitudinal sectional view showing another cylindrical resonator used in each example, and FIG. 6 (B) is a side view schematically showing the cylindrical resonator. FIGS. 7A and 7B are schematic diagrams showing the resonance modes of the cylindrical resonators. FIG. 8 (A) is a longitudinal sectional view showing a rectangular resonator used in each example, and FIG. 8 (B) is a side view schematically showing the rectangular resonator. 9 (A) and 9 (B) are schematic diagrams showing the resonance modes of the rectangular resonator. FIG. 10 is a block diagram showing an example of a conventional plasma generation reaction device. FIG. 11 is a view taken along the line AA ′ in FIG. FIG. 12 is a configuration diagram showing another example of the conventional plasma generation reaction device. 31,31a, 31b ... Microwave oscillator, 32,32'a, 32'b ...
… Isolator, 33 …… T-shaped branch pipe, 34 …… Cavity resonator as applicator, 34a, 34b …… Microwave inlet, 35a, 35b …… Power monitor, 36a, 36b …… Stub tuner, 37a, 37b, 37'a, 37'b ... Circulator, 38a,
38b, 38'a, 38'b ... Variable short circuit, 39a, 39b ... Phase shifter, 40, 60 ... Cylindrical resonator, 48 ... Substrate, 49 ... Substrate holder, 80 ... Rectangular resonance vessel.

Claims (1)

(57) [Claims] 1. A microwave is introduced into a mixed gas of hydrogen gas and an organic compound that decomposes and produces carbon by plasma,
On the surface of the object on the holding table in the applicator, carbon thin film,
In a plasma generating reactor for producing crystals, etc., a TE having a plurality of microwave inlets as the applicator.
A plasma generation reaction device characterized in that a cylindrical resonator of _11n resonance mode or a rectangular resonator of TE _m0n resonance mode is used, and a phase shifter capable of interlocking with each other is provided at each of the microwave inlets.