JPH053098A - Plasma generator - Google Patents

Abstract

PURPOSE:To make the generation of plasma easier by increasing the intensity of the electric field in a plasma generating space when the plasma is started to generate. CONSTITUTION:At the part positioned closer to an oscillator from the connection of a waveguide circuit and a plasma generating space 4, a movable stub 11 to move in and out to the waveguide 2g penetrating the tube wall of the waveguide 2g is provided. And, under the condition the movable stub 11 is advanced in the waveguide, a cavity resonator is composed by the part between the movable stub 11 and the plasma generating space 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma generator which supplies microwaves to a plasma generating space to generate plasma.

[0002]

2. Description of the Related Art CVD, which is one of the devices for forming a thin film
Plasma generated by microwaves is used in an apparatus, an etching apparatus for manufacturing a semiconductor, and the like. FIG. 7 shows a configuration example of a plasma CVD apparatus. In FIG. 7, 1 is a microwave oscillator, and 2 is a waveguide for supplying microwaves generated by the microwave oscillator to a plasma generation space 4 in a quartz tube 3. The waveguide circuit 2 is a circuit and is configured by a plurality of waveguides 2a to 2g. In the middle of the waveguide circuit 2, an isolator 5 for protecting the oscillator 1 from reflected waves and a power monitor 6 for measuring incident waves and reflected waves.
And an impedance matching device 7 for matching impedance in order to effectively transmit power to the load. The quartz tube 3 is provided in a state of penetrating the waveguide 2g at the end of the waveguide circuit. At the end of the waveguide 2g, the peak point of the electric field in the quartz tube 3 is adjusted. A termination mechanism 8'having a movable short-circuit plate is provided.

A substrate holder 9 is arranged in the quartz tube 3,
A substrate 10 is held on the holder 9. Quartz tube 3
Is connected to an exhaust device (not shown), and the inside of the quartz tube 3 is evacuated by the exhaust device.

The operating procedure for forming a thin film by the above CVD apparatus is as follows. First, after evacuating the inside of the quartz tube 3, a predetermined reaction gas (for example, CH4 + H2) is supplied from the inlet 3a of the quartz tube 3 into the quartz tube. Then, the plunger 8a 'provided on the terminal end mechanism 8'is manually operated to set the movable short-circuit plate in the terminal end mechanism at a predetermined position. After that, the microwave oscillator 1 is oscillated to generate a microwave having a predetermined frequency (usually 2.45 GHz). This microwave is a waveguide circuit 2
The plasma P is generated in the space 4 because it is supplied to the plasma generation space 4 inside the quartz tube 3.

[0005]

As described above, in the plasma generator for generating the plasma by supplying the microwave from the microwave oscillator 1 to the plasma generating space 4 through the waveguide circuit 2, the plasma generating space 4 is Depending on the process conditions such as the type and pressure of the gas supplied, it is difficult for the gas in the plasma generation space to be turned into plasma, and it may be difficult to start the plasma. Further, even if the plasma is once generated, the plasma may be biased or unstable in the plasma generation space, and the plasma may fail to start.

It is an object of the present invention to provide a plasma generator capable of facilitating plasma activation.

[0007]

The present invention relates to a plasma generator for generating a plasma by supplying a microwave generated by a microwave oscillator to a plasma generation space through a waveguide circuit.

According to the present invention, the wall of the waveguide is penetrated between the plasma generation space of the waveguide circuit and the first flange for mounting the waveguide on the oscillator side of the plasma generation space, and the drive machine is used. A movable stub that moves in and out of the waveguide is provided,
With the movable stub inserted into the waveguide, the cavity resonator is constituted by the portion of the waveguide circuit closer to the plasma generation space than the movable stub.

[0009]

As described above, the movable stub is provided in the portion located on the oscillator side of the coupling portion of the waveguide circuit with the plasma generation space, and the movable stub is introduced into the waveguide while being guided. If the cavity resonator is configured by the portion of the wave tube circuit that is closer to the plasma generation space than the movable stub,
When the plasma is started, the movable stub is allowed to enter the waveguide, so that a resonance state can be generated in the circuit on the plasma generation space side, so that the electric field in the plasma generation space can be sufficiently strengthened and the plasma It can be easily generated.

[0010]

EXAMPLE FIG. 5 shows an overall structure of an example in which the present invention is applied to the CVD apparatus shown in FIG. 7. In this example, the endmost portion where the quartz tube 3 is penetrated is shown. Waveguide 2
A movable stub 11 capable of moving in and out of the waveguide 2g is provided in a portion of g located closer to the oscillator than the quartz tube (plasma generation space).

Referring to FIGS. 1-4, the structure of the end of the waveguide circuit provided with the movable stub is shown in detail. In these figures, 2g is a rectangular waveguide arranged at the end of the waveguide circuit, and a quartz tube 3 is provided so as to penetrate almost the central portion in the longitudinal direction of the waveguide 2g.
An end plate 800 is attached to the end portion of the waveguide 2g, and the rod 8 is inserted into a hole 800a provided at the center of the end plate 800.
01 is movably inserted. At the end portion of the rod 801 located inside the waveguide 2g, the cylinder mounting plate 8
02 is fixed, and the air cylinder 80 is attached to the mounting plate 802.
3 is attached. The piston rod 804 of the air cylinder 803 is coupled to a movable short-circuit plate 805 that is movably provided in the waveguide 2g, and the piston rod 804 is
The movable short-circuit plate 805 reciprocates in the axial direction of the waveguide 2g with the displacement.

As shown in FIG. 3, guide bars 806 and 806 are fixed to the end plate 800, and these guide bars 806 and 806 slide with guide holes 802a and 802a formed in the mounting plate 802. The cylinder mounting plate 802 is movably fitted and movably supported in the axial direction of the waveguide 2g. Reference numeral 807 denotes a positioning member having a hole for sliding the rod 801 in the shaft center portion, and the positioning member 807 is fixed to the end plate 800. Also, this positioning member 80
7 is formed in a half-divided shape, and the diameter of the half-divided portion is reduced by a tightening tool so that the rod 801 can be supported by the end plate 800 integrally with the positioning member 807. That is, by integrally adjusting the rod 801 and the positioning member 807 with the rod 801 and the mounting plate 802 being properly adjusted in the axial direction of the waveguide 2g, the mounting position of the cylinder 803 is set to a desired position. be able to.

Further, in FIG. 3, reference numerals 808 and 808 denote stroke adjusting rods slidably fitted in through holes 800b and 800b provided in the end plate 800, and the end portions of the stroke adjusting rods 808 and 808 are Each is fixed to the movable short-circuit plate 805. Stroke adjusting rod 808,
The free end side of 808 is inserted into the holes provided in the adjusting tools 809 and 809. As shown in FIG. 4, a part of each of the adjusting tools 809 and 809 is formed in a half-divided shape, and the stroke-adjusting rods 808 and 808 are inserted by tightening the respective half-divided portions with a tightening tool. By reducing the diameter of the holes, the adjusting tools 809, 809 can be fixed to predetermined positions of the stroke adjusting rods 808, 808. That is, the adjusting tool 809
The position of the cylinder 803 on the protruding side of the piston rod 804 can be set by adjusting the fixed position of the cylinder. For example, with the cylinder 803 operated so that the piston rod 804 is pulled in, the movable short-circuit plate 80 is
The position of the rod 801 is adjusted so that the position of the front surface of 5 becomes the position of X2 in FIG. 1, and in this state, the rod 801 and the positioning member 807 are integrally fixed. Next, the cylinder 803 is operated so that the piston rod 804 projects, and the position of the adjusting tool 809 is adjusted so that the position of the front surface of the movable short-circuit plate 805 becomes the position of X1, and the adjusting tool 809 is moved to the stroke adjusting rod 808. Fixed to.

In this embodiment, the end plate 800 and the rod 80
1, mounting plate 802, cylinder 803, movable short-circuit plate 80
5, the positioning member 807, the stroke adjusting rod 808, and the adjusting tool 809 constitute the end portion mechanism 8.

According to the present invention, the wall of the waveguide is penetrated between the plasma generation space of the waveguide circuit and the first flange for mounting the waveguide on the oscillator side of the plasma generation space, and the drive machine is used. A movable stub is provided that moves in and out of the waveguide. In this embodiment, a hole 200a is provided by penetrating a tube wall of a portion of the waveguide 2g located on the oscillator side of the quartz tube 3, and a movable stub 11 is provided through the hole 200a. The movable stub 11 is adapted to be linearly moved by an air cylinder 13 fixed to a mounting block 12 fixed to the tube wall of the waveguide 2g, and the hole provided in the mounting block 12 and the waveguide. Hole 2 in the tube wall
It goes into and out of the waveguide 2g through 00a. The movable stub 11 is driven by the cylinder 13 and enters the waveguide 2g by a length E as shown in FIG.
It is adapted to be displaced between the inner surface of the cylinder 13 and the retracted position where it retracts to the same position, that is, between both ends of the stroke of the cylinder 13.

The movable stub 11 is approximately (1/2) .lambda.g1.n from the position X1 of the movable short-circuiting plate 805 where the gas inside the quartz tube 3 is easily turned into plasma when the tube wavelength is .lambda.g1.
(Where n is a positive integer).

For example, at the time of initial setting, the distance C between the movable short-circuit plate 805 and the movable stub 11 is C = λg1, and the movable short-circuit plate 80 is
5 is predicted to be (1/4) λg1 between the quartz tube 3 and the quartz tube 3, and the distance D between the movable stub 11 and the quartz tube 3 is D = (3 /
4) Let λg1. In this case, for example, 2.45GH
If the microwave of z is used, C in FIG.
The terminal position mechanism 8 is appropriately adjusted so that λg1 = 147.8 mm, and the front surface position of the movable short-circuit plate 805 is set to X1.

When the height of the waveguide 2g is F, the stroke E of the movable stub 11 is E = (0.4-0.
5) Set to F. For example, E when F = 54.6 mm
= 25mm is selected. The change of the position of the movable short-circuit plate 805 by the termination mechanism 8 will be described later.

Now, in the above plasma generator,
When activating the plasma, first the substrate 10 is placed in the quartz tube 3.
And the inside of the quartz tube 3 is evacuated. Then, a predetermined reaction gas is supplied into the quartz tube 3 to generate a microwave. Then, the cylinder 13 is operated to move the stub 11 into the waveguide 2g at a stretch by a predetermined length E. When the stub 11 is entered, the microwaves reflected and returned by the movable short-circuit plate 805 are reflected again at the stub 11 and travel to the movable short-circuit plate 805 side, so that the space between the stub 11 and the movable short-circuit plate 805 is reduced. Resonance occurs and the electric field in the quartz tube 3 becomes strong. Therefore, the gas in the quartz tube 3 is easily turned into plasma.

Once the plasma is generated, the stub 11
Is unnecessary, the cylinder 13 is operated in the reverse direction to retract the movable stub 11 as shown in FIG.

By the way, as described above, plasma is generated by adjusting the end portion mechanism 8 so that the distance between the stub 11 and the front surface of the movable short-circuit plate 805 becomes C. In some cases, the mounting state and the distance between the position X1 on the front surface of the terminal end mechanism 8 and the shaft core of the quartz tube 3 are not the desired value B, for example, (1/4) λg1. In this case, the plasma is biased in the quartz tube 3 and becomes unstable. In order to deal with this, the movable short-circuit plate 805 is moved by the termination mechanism 8 to adjust the plasma in the quartz tube 3 to a stable state. The position of the movable short-circuit plate 805 when the plasma is stable is the position of X2.

That is, as described above, the stub 11 is provided as shown in FIG.
Before and after the retreat, the position of the movable short-circuit plate 805 is displaced to the position of X2 by the terminal end mechanism 8. This maintains the plasma in a stable state.

In the above embodiment, the positional relationship between X1 and X2 may be reversed depending on the arrangement of each member of the waveguide 2g.

When the deviation of plasma occurs due to the type of reaction gas and the degree of vacuum in the quartz tube 3, the short-circuit plate 805 is movable in the axial direction of the waveguide 2g as described above. It is possible to stabilize the plasma, but when the type of gas in the quartz tube 3 does not change and the degree of vacuum etc. is maintained in a substantially steady state, or when the quartz tube 3, the movable stub 11, and the short-circuit plate are desired. If it is possible to arrange the short-circuit plate at the set position, the short-circuit plate can be fixed to the waveguide 2g.

In the above-mentioned embodiments, the CVD apparatus is taken as an example, but the present invention can be widely applied to a plasma generating apparatus which supplies a microwave to a plasma generating space through a waveguide to generate plasma. For example, a well-known ECR (Electron Cyclotron) as shown in FIG.
The present invention can be applied to an etching apparatus using a plasma generator of on-resonance type. In FIG. 6, 20 is a waveguide for supplying microwaves,
Reference numeral 21 is a plasma generation space formed of a quartz tube, 22 is a magnetic field generation coil, 23 is an ion extraction electrode, 24 is an etching deposition chamber, and 25 is a sample placed in the etching deposition chamber 24. In this case, a movable stub 11 that penetrates the tube wall of the waveguide 20 and goes in and out of the waveguide 20 by a driving machine such as an air cylinder 13 is attached to the waveguide 20, and the movable stub 11 and By forming a cavity resonator with the ion extraction electrode 23,
The electric field in the plasma generation chamber 21 can be enhanced to facilitate the generation of plasma.

In this case, the distance C between the end of the plasma generation space of the waveguide circuit and the movable stub 11 is C = (1/2) .multidot. λg2
n (where n is a positive integer).

In general, the waveguides 2a to 2g are generally premised on functionally minimizing distortion and twist, and the waveguide is manufactured in accordance with this, but in the present situation, it is possible to produce a single conductor. The waveguide has a length of up to about 350 to 400 mm, and a waveguide circuit having a length longer than that is constituted by coupling a plurality of waveguides by so-called mating flange coupling. By the way, when the flange portion of the waveguide exists between the movable stub 11 and the plasma generation space, the loss of the waveguide current flowing through the wall surface of the waveguide at the resonance portion closer to the plasma generation space than the movable stub is caused by the flange portion. To be large,
It becomes difficult to obtain a desired resonance state. That is, the movable stub 1
If the flange portion of the waveguide exists between 1 and the plasma generation space, it becomes difficult to bring the gas in the plasma generation space into a plasma state. Therefore, the movable stub 11 is provided between the plasma generation space and the first waveguide mounting flange on the oscillator side of the plasma generation space.

On the other hand, inside the waveguide in the resonance state, a large current flows in the wall surface of the waveguide, so that power loss occurs in the wall surface of the waveguide. Therefore, if the length of the resonance portion is too long, it becomes difficult to obtain a desired resonance state due to power loss. Therefore, the movable stub 11 usually has the above C = (1 /
2) In the relationship of λg · n, it is arranged at a position where 1 ≦ n ≦ 5.

In the above embodiment, the air cylinder 13 is used as the driving device for driving the movable stub, but an electric linear driving device such as an electromagnetic plunger can be used instead of the air cylinder. When an air cylinder or an electromagnetic plunger is used as the drive device for the movable stub, the movable stub can be moved almost instantaneously from the retracted position to the approach position or from the approach position to the retracted position.
The position of the movable stub can be switched quickly. However, the present invention is not limited to the case where a linear drive device such as a cylinder or an electromagnetic plunger is used as the drive device for the movable stub, and the rotary motion of the electric motor is converted into the linear motion by a rack and pinion mechanism or the like. It is also possible to use the above-mentioned thing as a drive machine of a movable stub.

[0030]

As described above, according to the present invention, the movable stub is provided in the portion of the waveguide circuit located on the oscillator side of the coupling portion with the plasma generation space, and the movable stub is provided in the waveguide. The cavity resonator is configured by the part of the waveguide circuit that is closer to the plasma generation space than the movable stub in the state that the movable stub is inserted into the waveguide when plasma is started. By setting it, there is an advantage that a resonance state can be generated in the circuit on the side of the plasma generation space and the electric field in the space can be sufficiently strengthened to facilitate generation of plasma. Further, since the movable stub can be retracted from the inside of the waveguide after the plasma is activated, there is no hindrance to the supply of microwave power.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing a state in which a movable stub is inserted into a waveguide according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an essential part showing a state in which the movable stub is retracted in the embodiment of the present invention.

FIG. 3 is a top view of FIG. 1 with a part cut away.

FIG. 4 is a right side view of FIG.

FIG. 5 is a configuration diagram showing an embodiment in which the present invention is applied to a CVD apparatus.

FIG. 6 is a cross-sectional view of essential parts showing an embodiment in which the present invention is applied to an ECR type etching apparatus.

FIG. 7 is a configuration diagram showing a conventional example.

[Explanation of symbols]

2g ... Waveguide, 3 ... Quartz tube, 4 ... Plasma generation space, 8
... Termination mechanism, 805 ... Movable short-circuit plate, 11 ... Movable stub, 13 ... Air cylinder.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location // H01L 21/205 7739-4M

Claims (1)

Claim: What is claimed is: 1. A plasma generator for supplying microwaves generated by a microwave oscillator to a plasma generation space through a waveguide circuit to generate plasma. A movable stub is provided between the generating space and the first flange for mounting the waveguide on the oscillator side of the plasma generating space, the movable stub penetrating the waveguide wall and coming in and out of the waveguide by a driver. A plasma generator in which a cavity resonator is formed by a portion of the waveguide circuit closer to the plasma generation space than the movable stub in a state where the stub is inserted into the waveguide.