JP5382958B2 - Plasma generator and plasma processing apparatus - Google Patents

Description

  The present invention relates to a plasma generation apparatus and a plasma processing apparatus, and more particularly to a plasma generation apparatus capable of forming plasma having an arbitrary distribution inside a plasma generation chamber, and a plasma processing apparatus such as an etching apparatus including the plasma generation apparatus.

  The dry process using plasma is used in a wide range of technical fields such as semiconductor manufacturing equipment, surface hardening of metal parts, surface activation of plastic parts, and non-chemical sterilization. For example, in manufacturing semiconductors and liquid crystal displays, various plasma treatments such as ashing, dry etching, thin film deposition, or surface modification are used. The dry process using plasma is advantageous in that it is low-cost, high-speed, and can reduce environmental pollution because it does not use chemicals.

  As a typical apparatus for performing such plasma processing, there is a “microwave excitation type” plasma processing apparatus that excites plasma with microwaves having a wavelength of several hundred MHz to several tens GHz. A microwave excitation type plasma source has a lower plasma potential than a high-frequency plasma source, and is therefore widely used for resist ashing without damage and anisotropic etching with a bias voltage applied.

  Semiconductor wafers to be processed and glass substrates for liquid crystal displays have been increasing in area year by year, so that a plasma generating apparatus having a high density and a uniform density over a large area is required to perform plasma processing on these.

  In response to such a requirement, a configuration in which an annular waveguide is disposed around the plasma generation chamber is disclosed (Patent Documents 1 and 2).

  27 and 28 are schematic views showing the annular waveguide disclosed in Patent Document 1. FIG. In the configuration shown in the figure, a plasma generation chamber (not shown) is arranged at the center of the annular waveguide 503. Microwaves 523 introduced from the microwave power source are distributed to the left and right by the distribution block 521 and propagate with a longer in-tube wavelength than free space. The microwave propagating in this way is emitted as a leaky wave 525 from a slot 522 installed every 1/2 or 1/4 of the guide wavelength. And it introduce | transduces through a dielectric permeation | transmission window etc. in the plasma generation chamber arrange | positioned inside this annular waveguide.

  FIG. 29 is a schematic diagram showing the main part of the microwave introduction device disclosed in Patent Document 2. As shown in FIG. That is, in the figure, reference numeral 101 denotes a cylindrical waveguide, and reference numeral 102 denotes a plurality of slots formed on the inner side wall of the cylindrical waveguide 101 in order to introduce microwaves from the cylindrical waveguide 101 into the plasma processing chamber. , 103 are microwave introduction portions for introducing microwaves into the cylindrical waveguide 101.

  A plasma generation chamber (not shown) for generating plasma is installed at the center of the cylindrical waveguide, and microwaves are introduced from slots 102 provided on the inner side wall of the waveguide.

  When an annular waveguide as illustrated in FIGS. 27 to 29 is used, there is a possibility that plasma can be generated over a larger area as compared with a conventional antenna type plasma generator.

Japanese Patent Laid-Open No. 9-306900 Japanese Patent No. 2886752

  However, in any of the plasma generators illustrated in FIGS. 27 to 29, the microwaves formed in the annular waveguide form a standing wave field, and leakage from the standing wave field is caused. Based on the idea of extracting waves. This is apparent from a configuration in which microwaves are taken out from a plurality of narrow slots 102 and 522 provided at intervals of 1/4 of the guide wavelength, for example.

  When a wave field due to standing waves is formed, there is a problem that a “standing wave mode jump” in which the microwave mode suddenly changes occurs. “Standing wave mode jump” occurs spontaneously, and even if external conditions (for example, gas pressure, microwave power, etc.) are reproduced, the plasma density cannot be reproduced and changes spontaneously or suddenly. There is. As a result, it becomes difficult to form a uniform plasma over a large area.

  On the other hand, as illustrated in FIGS. 27 to 29, when microwaves are introduced into the chamber through a plurality of slots, the impedance of these slots varies depending on the electron density of the plasma. is there. That is, in order to form a uniform plasma in the chamber, it is necessary to distribute the microwaves equally to each of the plurality of slots. To equalize the microwave, the impedance of all loads (ie, slots) must be the same. However, in the case of plasma, since the impedance to the microwave also changes depending on the increase / decrease of the electron density, there arises a phenomenon that the microwave cannot be divided even if the microwave distributor is completely symmetric. That is, the plasma density has “fluctuations”. The plasma spontaneously enters a state in which microwaves are most easily absorbed in total, but this is not necessarily the state in which the power of the microwaves is equally divided, and in most cases, the electron density of the plasma differs from slot to slot. That is, the impedance to the microwave fluctuates for each slot, and the microwave cannot be divided equally. As a result, the microwave cannot be uniformly introduced into the chamber, and it becomes difficult to form a uniform plasma.

  The present invention has been made on the basis of recognition of such problems, and an object thereof is to provide a plasma generator capable of forming plasma with a uniform distribution over a large area based on an idea different from the conventional one, and the plasma generator having the same. It is to provide a plasma processing apparatus.

が実質的に成立するようにしたことにより、
前記導入導波管から前記方向性結合器を介して前記環状共振器を励振させて前記環状共振器において前記マイクロ波の進行波を形成し、
前記複数のアプリケータは前記プラズマ発生室にマイクロ波を導入する誘電体から形成された導波体をそれぞれ有し、前記導波体から前記プラズマ発生室に導入されたマイクロ波によりプラズマを生成可能としたことを特徴とする。
In order to achieve the above object, the plasma generator of the present invention comprises:
A plasma generation chamber capable of maintaining an atmosphere depressurized from the atmosphere;
An introduction waveguide;
An annular resonator that resonates the traveling wave of the microwave;
A directional coupler for coupling the introduction waveguide and the annular resonator;
A plurality of couplers for distributing microwaves from the annular resonator;
A plurality of applicators coupled to each of the plurality of couplers and spaced apart from each other for introducing microwaves into the plasma generation chamber;
With
When the amplitude coupling coefficient of the directional coupler is C ₀ , the coupling coefficient of each of the plurality of couplers is C _i , and the propagation coefficient of the microwave that goes around the annular resonator is T,

By making it substantially hold,
Wherein the introduction waveguide via the directional coupler by exciting the annular cavity to form a traveling wave of the microwave in the annular resonator,
The plurality of applicators each have a waveguide formed of a dielectric material that introduces microwaves into the plasma generation chamber, and plasma can be generated by the microwaves introduced from the waveguide into the plasma generation chamber. It is characterized by that.

  According to the said structure, the plasma generator which can form the plasma of uniform distribution over a large area can be provided.

The waveguide further includes an introduction waveguide, and a directional coupler that couples the introduction waveguide and the annular resonator, and the annular resonator passes through the directional coupler from the introduction waveguide. If the microwave traveling wave is formed in the annular resonator by exciting the traveling wave, a wave field due to the traveling wave can be reliably formed in the annular resonator.

が実質的に成立するものとすれば、導入導波管におけるマイクロ波の反射を解消できる。 On the other hand, when the coupling coefficient of the directional coupler is C ₀ and each coupling coefficient of the plurality of couplers is C _i ,

Is substantially satisfied, the reflection of microwaves in the introduction waveguide can be eliminated.

  Further, if the amplitude coupling coefficient of each of the plurality of couplers is set low so that the impedance to the microwave does not substantially change even if the electron density of the plasma changes, an annular resonance The fluctuation of the resonance condition and the distribution balance of the microwave can be suppressed.

  Further, if the total power coupling coefficient of each of the plurality of couplers is 20% or less, even if the electron density of the plasma fluctuates, the change in impedance with respect to the microwave is suppressed to be substantially low. It is possible to suppress fluctuations in resonance conditions and microwave distribution balance in the annular resonator.

  Further, if the pipe and the internal part of the annular resonator are formed so that the round-trip phase difference of the traveling wave propagating through the inside is substantially equal to an integral multiple of 360 degrees, It is possible to excite resonance by waves.

  If the coupling coefficient between the applicator and the plasma is larger than the coupling coefficient between the coupler and the annular resonator, the microwave distributed by the coupler is introduced into the plasma generator with low loss. can do.

  Further, if the plurality of couplers are directional couplers, it is possible to perform extraction that matches the directionality of the traveling wave excited by the annular resonator.

  On the other hand, the plasma processing apparatus of the present invention includes any one of the above plasma generators, and enables plasma processing of an object to be processed by the plasma generated by the microwave introduced through the applicator. It is characterized by that.

As described above in detail, according to the present invention, a plasma generator and a plasma processing apparatus capable of forming a uniform plasma over a large area can be realized at low cost.
Therefore, for example, it is possible to easily form a uniform plasma treatment over a large area, or conversely form a strong plasma treatment locally.
As a result, plasma processing such as etching, ashing, thin film deposition, surface modification or plasma doping can be carried out uniformly and quickly on large-area semiconductor wafers, liquid crystal display substrates, etc. It is also possible to perform local plasma processing on the object to be processed, which has a great industrial advantage.

It is a conceptual diagram for demonstrating the principal part basic composition of the plasma generator concerning embodiment of this invention. FIG. 4 is a conceptual diagram for explaining the operation of a directional coupler 20. It is a conceptual diagram for comparing and explaining “traveling wave distribution” and “standing wave distribution”. It is a conceptual diagram which illustrates the principal part basic composition of the plasma generator concerning the 2nd Embodiment of this invention. It is a conceptual diagram which illustrates the principal part basic composition of the plasma generator concerning the 3rd Embodiment of this invention. It is a conceptual diagram which illustrates the principal part basic composition of the plasma generator concerning the 3rd Embodiment of this invention. It is a conceptual diagram which illustrates the principal part basic composition of the plasma generator concerning the 4th Embodiment of this invention. It is a conceptual diagram which illustrates the principal part basic composition of the plasma generator concerning the 4th Embodiment of this invention. It is a schematic plan view showing the plasma generator of the Example of this invention. FIG. 10 is a sectional view taken along line AA in FIG. 9. It is the BB sectional view taken on the line of FIG. It is a schematic diagram showing the directional coupler couple | bonded by the single hole. It is a schematic diagram showing the directional coupler couple | bonded by the bete hole. It is a schematic diagram showing the directional coupler couple | bonded by two holes. It is a schematic diagram showing the directional coupler couple | bonded by the cross-shaped slit. It is a schematic diagram showing the directional coupler couple | bonded by the loop. It is a schematic cross section which illustrates the structure of the plasma processing apparatus of this invention. It is a conceptual diagram showing the introduction part of the microwave to the annular traveling wave resonator in this embodiment. It is a conceptual diagram showing the applicator which made output variable using reflected wave R2. It is a schematic diagram showing the specific example of the AA line cross-section of the part of an applicator. It is a schematic diagram showing the BB sectional structure of FIG. It is a schematic plan view for demonstrating arrangement | positioning of the applicator in the plasma generator of the Example of this invention. It is a schematic cross section showing the structure of the plasma generator of the Example of this invention. It is a schematic diagram which illustrates distribution of ashing speed in case the power distribution of six applicators is not uniform. It is a schematic diagram which illustrates distribution of ashing speed in case the power distribution of six applicators is not uniform. It is a schematic diagram showing the distribution of the ashing speed obtained when the variable short plunger 58 of No. 1 applicator is adjusted to an optimal position. 10 is a schematic diagram showing an annular waveguide disclosed in Patent Document 1. FIG. 10 is a schematic diagram showing an annular waveguide disclosed in Patent Document 1. FIG. FIG. 10 is a schematic diagram illustrating a main part of a microwave introduction device disclosed in Patent Document 2.

  Hereinafter, embodiments of the present invention will be described in detail with reference to specific examples.

  FIG. 1 is a conceptual diagram for explaining a basic configuration of a main part of a plasma generator according to an embodiment of the present invention.

  The plasma generator of this embodiment includes an introduction waveguide 70, a directional coupler 20, an annular traveling wave resonator 10, a plurality of couplers 42, and an applicator coupled to each of these couplers 42. 50 and a plasma generation chamber 60 connected to the applicator 50. A microwave M output from a microwave power source (not shown) is introduced from the introduction waveguide 70 through the directional coupler 20 to the annular traveling wave resonator 10 to excite traveling wave resonance.

  The directional coupler 20 is connected to the introduction waveguide 70 in an annular manner so that only a propagation component in one of two opposite directions that can circulate and propagate through the annular traveling wave resonator 10 is excited. The wave resonator 10 is coupled. That is, the microwave power is supplied from the introduction waveguide 70 to the annular traveling wave resonator 10 via the directional coupler 20 and excites a propagation component circulating in the annular traveling wave resonator 10 in one direction.

FIG. 2 is a conceptual diagram for explaining the operation of the directional coupler 20.
That is, the directional coupler 20 has, for example, an input port 21 and an output port 22. The microwave component M 2 is input from the input port 21 to the annular traveling wave resonator 10, and the microwave component M 3 is output from the annular traveling wave resonator 10 to the output port 22. The output from the output port 22 of the directional coupler 20 is absorbed by a matched dummy load 72.

  In the directional coupler 20 and the annular traveling wave resonator 10, the amplitudes of the microwave component M 1 propagating through the introduction waveguide 70 and the microwave component M 3 output from the annular traveling wave resonator 10 to the waveguide 70. And the phases of the microwave component M2 input from the introduction waveguide 70 to the annular traveling wave resonator 10 and the microwave component M4 propagating through the annular traveling wave resonator 10 are the same. The phase condition is adjusted so that When such a matching is formed, the microwave components M1 and M3 are out of phase and cancel each other, so that the microwave power in the dummy load 72 is the lowest, and the reflected wave in the introduction waveguide 70 is substantially reduced. not exist.

  As described above, by exciting the traveling traveling wave resonator 10 via the directional coupler 20, only the unidirectional microwave component is supplied to the traveling traveling wave resonator 10, and the wave field caused by the traveling wave is supplied. Is formed. In other words, in the traveling wave resonator 10, the formation of a standing wave due to the introduction of the reflected wave can be prevented.

  Further, in the present invention, the condition that the traveling wave introduced in this way resonates in the annular traveling wave resonator 10 is satisfied. Specifically, the pipe and internal components of the annular traveling wave resonator 10 are formed such that the round-trip phase difference of the traveling wave propagating through the inside is substantially equal to an integral multiple of 360 degrees. The in-tube wavelength of the microwave traveling wave propagating through the annular traveling wave resonator 10 can be appropriately determined according to the size of the plasma generation chamber 60 and the conditions such as the plasma generated in the discharge space. That is, the annular traveling wave resonator 10 has a path length that is an integral multiple of the in-tube wavelength when the microwave resonates in the state attached to the plasma generation chamber 60, and the microwave passes through the annular traveling wave resonator 10. It is only necessary to make a round so that the phase of the wave does not change.

  Then, when the microwave propagates as a traveling wave in the annular traveling wave resonator 10 having such a path length, resonance occurs and its strength increases. By introducing a microwave into the plasma generation chamber 60 from such a traveling wave in a resonance state, it is possible to form a uniform and high-strength plasma. As will be described in detail later, when the resonance frequency of the annular traveling wave resonator 10 deviates due to factors such as mechanical accuracy, a phase adjuster and an intensity monitor are provided, and the resonance frequency is adjusted by adjusting the phase difference. Can also be adjusted.

  Resonant excitation of traveling waves formed according to the present invention cannot be obtained with a conventional plasma generator using an annular waveguide as illustrated in FIGS. For example, in the case of the annular waveguide 503 shown in FIGS. 27 and 28, the microwave 523 introduced into the waveguide is divided into two by the distribution block 521 provided at the entrance, and proceeds in the opposite directions. To do. Therefore, these distributed waves interfere with each other to form a standing wave. In order to extract such a standing wave, the interval between the slots (522) provided in the annular waveguide (503) must be 1/2 or 1/4 of the wavelength of the standing wave. When such a standing wave is formed, the intensity of the plasma also becomes non-uniform corresponding to the magnitude of the amplitude.

  Also, in the case of the annular waveguide 101 illustrated in FIG. 29, the microwaves introduced from the introduction unit 103 are divided into left and right and propagate in opposite directions, so that they do not become traveling waves. In more detail, in the case of the waveguide 101, among the microwaves introduced from the introduction unit 103 and divided into left and right, the intensity of the wave traveling leftward (counterclockwise) toward the drawing is higher. However, even with the structure shown in FIG.

  For example, in the case of the waveguide 503 shown in FIG. 27 and FIG. 28, the microwave is distributed by the distribution block 521 to the left and right at an intensity ratio of approximately 50%: 50%. On the other hand, in the case of the waveguide 101 of FIG. 29, the left / right distribution ratio of the microwave introduced from the introducing portion 103 is about 60%: 40% at most. As a result, a standing wave is formed in the annular waveguide 101, and the intensity of the microwave is not uniform. That is, unless the directional coupler 20 is arranged at the introduction portion of the annular traveling wave resonator 10 as in the present invention, it is difficult to form a microwave traveling wave field in the annular waveguide. .

  According to the present invention, the microwave is supplied to the annular traveling wave resonator 10 via the matched directional coupler 20, thereby eliminating the influence of the reflected wave and the annular traveling wave resonator. 10, a microwave wave field can be formed by traveling waves. Furthermore, the annular traveling wave resonator 10 is configured so that the traveling wave of the microwave formed in this way resonates.

  The microwave component M2 input from the introduction waveguide 70 to the annular traveling wave resonator 10 has a role of a “spring” of a pendulum type timepiece. That is, it has a role of compensating for a loss component that is emitted to the plasma generation chamber among the traveling waves propagating through the annular traveling wave resonator 10 and contributes to the formation of the plasma. Thus, in the annular traveling wave resonator 10, a wave field is always formed by a traveling wave of a microwave having a constant intensity.

  Returning to FIG. 1 and continuing the description, in the present embodiment, a plurality of couplers 42 are coupled to the annular traveling wave resonator 10, and the plasma generation chamber 60 is coupled from the coupler 42 via the applicator 50. Microwave is introduced in That is, a waveguide space is formed inside the annular traveling wave resonator 10, and a traveling wave of the microwave propagates under a resonance condition. A part of the microwave is taken out through the coupler 42 and introduced into the plasma generation chamber 60 through the applicator 50, and the plasma P is generated and maintained.

In other words, in the present invention, the traveling wave power formed in the annular traveling wave resonator 10 can be distributed to the plurality of couplers 42 and extracted.
FIG. 3 is a conceptual diagram for comparing and explaining “traveling wave distribution” and “standing wave distribution”.
That is, FIG. 6A shows “traveling wave distribution”, where the coupler 42 is coupled to the waveguide 100 through which the traveling wave of the microwave propagates, and the microwave is distributed. In the case of a traveling wave, the intensity of the microwave propagating through the waveguide 100 is uniform with respect to the traveling direction, so that the intensity is almost constant regardless of where it is taken out, and the balance of distribution is maintained. Is easy.
On the other hand, in the case of “standing wave distribution”, the intensity of the microwave is expressed by the standing wave intensity distribution, that is, the antinodes and “nodes” of the standing wave, as shown in FIG. It is uneven. Therefore, the intensity of the microwave changes depending on the position of the coupler 42. Conversely, in order to maintain a constant intensity, the arrangement of the couplers 42 must be determined according to the wavelength of the standing wave.

  According to the present invention, as illustrated in FIG. 3A, the microwave is extracted (distributed) from the wave field of the resonant traveling wave, so that the extraction position can be set freely. As a result, it is possible to obtain an effect that the coupler 42 and the applicator 50 can be arranged at optimum positions in accordance with the shape of the plasma generation chamber 60 and the distribution of gas pressure.

On the other hand, another important numerical value in the present invention is a coupling coefficient C _i of the coupler 42 for extracting microwaves. In short, this corresponds to the ratio of the intensity of the microwave extracted from the coupler 42 to the intensity of the microwave propagating in the annular traveling wave resonator 10 toward the coupler 42. Therefore, the higher the coupling coefficient C _i is, the more efficiently the microwave is extracted from the annular traveling wave resonator 10.

In the present invention, the coupling coefficient C _i of the coupler 42 is lowered. By reducing the coupling coefficient C _i , it is possible to make it less susceptible to changes in the impedance of the applicator 50 due to the state of the plasma P. That is, as described above, the plasma P has “fluctuations”, and its electron density varies spatially and temporally. When the electron density of the plasma P changes, the impedance to the microwave also changes. The change in the state of the plasma P in the vicinity of a specific applicator 50 changes the resonance condition of the annular traveling wave resonator 10 and also affects the microwave extraction balance in the other applicators 50. That is, the microwave concentrates on the portion where the electron density of the plasma P is high, and it becomes difficult to maintain the uniform plasma P.

  On the other hand, according to the present invention, first, the wave field of the resonant traveling wave is formed, so that the microwave mode is single and the concentration on the specific applicator 50 is suppressed. Furthermore, in the present invention, the coupling coefficient of the coupler 42 that extracts the microwave from the annular traveling wave resonator 10 is kept low, so that the influence of fluctuations in the impedance of the plasma P does not affect the annular traveling wave resonator 10. To do. That is, by suppressing the coupling coefficient of the coupler 42 to be low, the fluctuation of the resonance condition of the annular traveling wave resonator 10 due to the change of the impedance of the plasma P and the fluctuation of the distribution balance among the plurality of couplers 42 are suppressed. Can do. As a result, a wave field caused by resonance of the traveling wave is always formed under a predetermined condition regardless of the state of the plasma P, and a microwave can be distributed from the wave field to the plurality of applicators 50 with a predetermined balance. it can.

According to the study of the present inventor, by suppressing the coupling coefficient C _i in the coupler 42 to several percent or less, it becomes difficult to receive a change in the impedance of the plasma P, and sufficiently stable microwave excitation can be achieved. I understood. This point will be described below with reference to FIG.

The annular traveling wave resonator 10 is adjusted so as to satisfy the resonance condition (that is, adjusted so that the phase difference before and after the microwave goes around the annular traveling wave resonator 10 is an integral multiple of 360 degrees). ) Here, the intensity of the microwave M, the propagation coefficient of the microwave around the annular traveling wave resonator 10 (transmission coefficient) T, the coupling coefficient of the directional coupler 20 and C ₀ to be input.

Then, the microwave intensity M _dummy in the dummy load 72 is given by the following equation.

It is desirable that all the microwave power is input to the annular traveling resonator 10, and at this time, the microwave power in the dummy load 72 becomes zero. That is, it is desirable that the condition of M _dummy = 0 is satisfied. Therefore, it is desirable that the following equation is satisfied.

The following equation is obtained from the equation (2).

  The propagation coefficient T when the microwave goes around the annular traveling wave resonator 10 depends on a loss generated on the inner wall of the waveguide portion and a loss caused by the power being emitted from the coupler 42 to the plasma. The loss caused on the inner wall of the waveguide is very small and can be ignored. Accordingly, the propagation coefficient T is substantially determined solely by the release of power to the plasma via the coupler 42.

Here, the total transmission coefficient T is an integration of the propagation coefficients T ₁ , T ₂ ,... In each coupler 42 as represented by the following equation.

When the reflection at the coupler 42 is very small and the loss is small, the propagation coefficient T _i in each coupler 42 can be expressed by the following equation using the coupling coefficient C _i .

  Substituting equation (5) into equation (4) and combining with equation (3) yields the following conditions.

Therefore, when the coupling coefficient C ₀ of the directional coupler 20 is set as shown in equation (6), the microwave power introduced from the introduction waveguide 70 into the annular traveling wave resonator 10 and the annular traveling wave resonator 10 The amount of attenuation is balanced, and the reflected wave in the introduction waveguide 70 can be almost eliminated.

Here, if the coupling coefficient C _i is kept low, the radio wave intensity in the annular traveling wave resonator 10 is increased, and the effect of being less susceptible to plasma is obtained.
That is, the intensity of the microwave in the annular traveling wave resonator 10 is determined by the total transmission coefficient T expressed by the equation (4). As the total propagation coefficient T approaches 1 (that is, attenuation is suppressed), the intensity of the microwave in the annular traveling wave resonator 10 increases. When the expression (3) is satisfied and the coupling is good, the intensity of the microwave in the annular traveling wave resonator 10 is given by the following expression.

Therefore, it is necessary to make (1-T ² ) ^1/2 as small as possible. In other words, this means that the total coupling coefficient T needs to be as close to 1 as possible. Considering the equation (6), it can be seen that in order to bring the total coupling coefficient T close to 1, all (1-C _i ² ) ^1/2 need to be close to 1. This means that all coupling coefficients C _i need to be kept as low as possible.

  In summary, the intensity of the microwave in the annular traveling wave resonator 10 of the present invention can be expressed by the following equation.

(8) In order to increase the strength M ₄ in formula, it is necessary to reduce the respective coupling coefficients C _i. When each of the coupling coefficients C _i is sufficiently smaller than 1, Equation (8) can be approximated by the following equation.

倍である」ことを表している。
ちなみに、複数の結合器４２のパワー結合係数の合計が２０パーセントの場合、環状進行波共振器１０内を伝搬しているマイクロ波のパワーは、導入パワーの５倍にもなる。以上、環状進行波共振器１０内でのマイクロ波の強度について説明した。 Here, since the coupling coefficient C _i is a coefficient representing the ratio of the amplitude, it is more precisely called “amplitude coupling coefficient” and is usually represented by “decibel (dB)”. . On the other hand, C _i ² is called a “power coupling coefficient” and is usually represented by “percent (%)”. The power coupling coefficient represents what percentage of the microwave power branches from the main waveguide to the coupled port. Equation (9) is “the power in the annular traveling wave resonator 10 is the input power.

Is doubled. "
Incidentally, when the sum of the power coupling coefficients of the plurality of couplers 42 is 20%, the power of the microwave propagating in the annular traveling wave resonator 10 is five times the introduced power. The microwave intensity in the annular traveling wave resonator 10 has been described above.

パーセントになる（（９）式参照）。 Next, the influence of plasma will be described.
The above explanation is a theory when there is no reflection in each applicator 50. In practice, some applicator 50 produces some reflection. The total power input to all applicators 50 is equal to the introduced power, and the microwave power in the annular traveling wave resonator 10 is

It becomes a percentage (see equation (9)).

In the worst case, if all the microwaves are reflected by all the applicators 50 due to plasma fluctuations and they travel in the opposite direction to the traveling wave, it will occur in the annular traveling wave resonator 10. The ratio of microwave reflection power / incident power is expressed by the following equation.

が小さければ、プラズマの揺らぎによる反射が生じた場合でも、環状進行波共振器１０内でのマイクロ波の伝搬状態は殆ど変化せず、マイクロ波の分配を維持できる。つまり、結合係数Ｃ _i を小さくすると、プラズマの揺らぎが生じてもマイクロ波の反射の増大を抑制できる。実用的には、環状進行波共振器１０内でのマイクロ波の反射波パワーが入射波パワーの２０パーセントを超えないようにするために、結合器４２のそれぞれのパワー結合係数の合計が２０パーセント以下となるように調整することが望ましい。 On the contrary,

Is small, the propagation state of the microwave in the annular traveling wave resonator 10 hardly changes even when the reflection due to the fluctuation of the plasma occurs, and the distribution of the microwave can be maintained. That is, if the coupling coefficient C _i is reduced, an increase in microwave reflection can be suppressed even if plasma fluctuation occurs. In practice, the total power coupling coefficient of each coupler 42 is 20 percent so that the reflected microwave power in the annular traveling wave resonator 10 does not exceed 20 percent of the incident wave power. It is desirable to adjust so that it becomes the following.

As described above, in the present invention, if the coupling coefficient C _i in the coupler 42 is kept low, the radio wave intensity in the annular traveling wave resonator 10 is increased and the effect of being less susceptible to plasma. Is obtained.

As a method of adjusting the coupling coefficient C _i , for example, in the case of a configuration having an opening among various types of directional couplers described later, there is a method of adjusting the size and position of the opening. Of course, besides this, the coupling coefficient C _i can be adjusted to the optimum range by various methods according to the form of the directional coupler.

If the coupling coefficient C _i of the coupler 42 is lowered, the power of the extracted microwave is also reduced. However, by setting the number of couplers 42 and applicators 50 appropriately, a sufficiently strong and uniform plasma P can be increased. It can be excited over the area.

In the present invention, the coupling coefficients C _i of the plurality of couplers 42 need not all be the same. For example, when it is desired to provide a distribution in the intensity of microwaves to be introduced according to the gas flow and pressure distribution in the plasma generation chamber 60 or the shape and size of the workpiece, the coupling coefficient C of the coupler 42 is used. _i may be appropriately changed for each place. In this case as well, the coupling coefficient C _i may be set within a range that is not easily affected by the change in the impedance of the plasma P.

Here, in the present invention, the coupling coefficient C _i of the coupler 42 is an element that determines the attenuation coefficient of the traveling wave propagating in the annular traveling wave resonator 10. That is, when the traveling wave of the microwave makes a round around the annular traveling wave resonator 10, the intensity is attenuated by the accumulated amount of the coupling coefficients C _i of all the couplers 42. This attenuated amount is introduced into the plasma generation chamber 60 and contributes to the generation of the plasma P. Then, the microwave power absorbed during one round of the traveling wave resonator 10 is replenished from the introduction waveguide 70 via the directional coupler 20.

Therefore, when the coupling coefficient C ₀ of the directional coupler 20 is set as described above with respect to the expression (6), the microwave power introduced from the introduction waveguide 70 to the annular traveling wave resonator 10 and the annular traveling wave resonance are set. The amount of attenuation in the vessel 10 is balanced.

That is, if the coupling coefficient C ₀ of the directional coupler 20 is set as shown in equation (6), the microwave power in and out of the annular traveling wave resonator 10 is balanced, and the reflected wave in the introduction waveguide 70 is completely transmitted. Can be eliminated.

Next, another embodiment of the present invention will be described.
FIG. 4 is a conceptual diagram illustrating the basic configuration of the main part of the plasma generating apparatus according to the second embodiment of the invention. In this figure, the same elements as those described above with reference to FIGS. 1 to 3 are denoted by the same reference numerals, and detailed description thereof is omitted.
In the present embodiment, a directional coupler 40 is provided as a coupler for taking out the microwave from the annular traveling wave resonator 10. Since the microwave propagating in the annular traveling wave resonator 10 is composed only of the traveling direction wave, the same result can be obtained when the microwave is extracted by the directional coupler 40. However, it is desirable that the coupling coefficient C _i of the coupler 40 be suppressed to several percent or less, as in the case described above with reference to FIG. By keeping the coupling coefficient of the coupler 40 low, fluctuations in the resonance conditions of the annular traveling wave resonator 10 due to changes in the impedance of the plasma P and fluctuations in the distribution balance among the plurality of couplers 40 can be suppressed. . As a result, a wave field caused by resonance of the traveling wave is always formed under a predetermined condition regardless of the state of the plasma P, and a microwave can be distributed from the wave field to the plurality of applicators 50 with a predetermined balance. it can.

5 and 6 are conceptual diagrams illustrating the basic configuration of the main part of the plasma generating apparatus according to the third embodiment of the invention. Also in these drawings, the same elements as those described above with reference to FIGS. 1 to 4 are denoted by the same reference numerals, and detailed description thereof is omitted.
In the present embodiment, the annular traveling wave resonator 10 is provided with a power monitor 80 and a phase shifter 90. That is, in the present invention, the annular traveling wave resonator 10 excites resonance due to the traveling wave of the microwave. For this purpose, as described above with reference to FIG. 1, the annular traveling wave resonator 10 and its internal components are such that the round-trip phase difference of the traveling wave propagating through the interior is substantially equal to an integral multiple of 360 degrees. Need to be generated. Further, the in-tube wavelength varies depending on the size of the plasma generation chamber 60 and the conditions such as the plasma generated in the discharge space.

On the other hand, according to the present embodiment, the intensity of the microwave propagating through the annular traveling wave resonator 10 is measured by the power monitor 80, and the phase is adjusted by the phase adjuster 90. The resonance condition can be adjusted to an optimum range. That is, adjustment may be made by the phase adjuster 90 so that the microwave travels around the annular traveling wave resonator 10 and the phase of the wave does not change. In this case, the number of phase adjusters 90 may be one as illustrated, or a plurality of phase adjusters 90 may be provided.
In addition, as illustrated in FIG. 6, a dummy load 72 may be provided at the end of the introduction waveguide 70, and a power monitor 82 may be provided along with the dummy load 74 in the midway path to monitor the microwave power.
In any case, when the microwave resonance condition is satisfied, the reflected power Pr is significantly reduced with respect to the incident power Pf.
7 and 8 are conceptual diagrams illustrating the basic configuration of the main part of the plasma generating apparatus according to the fourth embodiment of the invention. Also in these drawings, the same elements as those described above with reference to FIGS. 1 to 6 are denoted by the same reference numerals, and detailed description thereof is omitted.
In the present embodiment, a directional coupler 40 is provided as a coupler for extracting the microwave from the annular traveling wave resonator 10, and the phase with the power monitor 80 is adjusted in order to adjust the resonance condition of the microwave. A regulator 90 is provided. The functions and effects relating to these elements are as described above with reference to FIGS.

FIG. 9 is a schematic plan view showing the plasma generator of the embodiment of the present invention.
FIG. 10 is a cross-sectional view taken along the line AA.
Moreover, FIG. 11 is the BB sectional drawing.

That is, in the plasma generator of this embodiment, the microwave M is introduced from the introduction waveguide 70 to the annular traveling wave resonator 10 through the directional coupler 20. In FIG. 9, the annular traveling wave resonator 10 is shown in a hexagonal shape, but the present invention is not limited to this, and various annular shapes such as an annular shape, an elliptical shape, and a polygonal shape may be used. The directional coupler 20 is provided with two openings 21 and 22 for introducing microwaves, and the interval L is expressed by the following equation when the guide wavelength of the annular traveling wave resonator 10 is λ _g. Is set to a value.

  In this way, only the microwave component in the traveling direction can be introduced from the introducing waveguide 70 into the annular traveling wave resonator 10. The microwave introduced into the annular traveling wave resonator 10 forms a traveling wave resonant wave field and is taken out by the coupler 44 having a low coupling coefficient. In the case of the present embodiment, these couplers 44 also have two openings, respectively, and can extract microwaves of traveling direction components.

  These couplers 44 may be directional couplers. For example, as shown in FIGS. 10 and 11, the couplers 44 may have two slit-shaped openings inclined with respect to the traveling direction of the microwave M. it can. The microwave M can be taken out from the annular traveling wave resonator 10 through these two openings. The microwave M taken out through the coupler 44 propagates through the introduction waveguide 52 of the applicator 50 and is introduced into the plasma generation chamber 60 through the waveguide 54 of the applicator 50.

  As a material for the waveguide 54, it is necessary to transmit microwaves with low loss and to maintain airtightness by partitioning the introduction waveguide 52 and the plasma generation chamber 60. Examples of such a material include a dielectric such as quartz, alumina, or sapphire. These dielectrics have a low power factor for microwaves, have mechanical strength that can withstand the pressure difference between vacuum and atmospheric pressure, have good heat resistance, and even when sputtered or etched by plasma, There is also a low risk of contaminating the workpiece in the chamber.

  As described above, by suppressing the coupling coefficient of the coupler 44 to be low, fluctuations in the resonance conditions of the annular traveling wave resonator 10 due to changes in plasma impedance and fluctuations in the distribution balance among the plurality of couplers 44 are suppressed. can do. On the other hand, the coupling coefficient when the microwave M thus extracted from the annular traveling wave resonator 10 to the introduction waveguide 52 of the applicator is introduced into the plasma generation chamber 60 through the waveguide 54 is as follows. It should be high enough. That is, by increasing the coupling coefficient of the applicator 50, it is possible to suppress the loss and increase the plasma generation efficiency. In this manner, plasma of a predetermined gas can be generated by the microwave M introduced into the plasma generation chamber 60 via the waveguide 54.

  9 to 11 exemplify the waveguide space of the annular traveling wave resonator 10 having a substantially rectangular cross section, but the present invention is not limited to this. That is, the cross-sectional shape of the waveguide space of the annular traveling wave resonator 10 is circular, elliptical in consideration of the arrangement relationship with the plasma generation chamber, the connection relationship with the introduction waveguide 70, or the plasma distribution. They can be semicircular, polygonal, symmetric or asymmetrical indeterminate.

  Next, some specific examples of the directional couplers 20 and 40 that can be used in the plasma generator of the present invention will be introduced.

  FIG. 12 is a schematic diagram illustrating a directional coupler coupled by a single hole. That is, as illustrated in the figure, a structure in which the waveguide 1 and the waveguide 5 overlap with each other on the H plane and are coupled by a relatively small single hole A can be exemplified. In such a case, the waveguide 1 is excited by the electric field leaking from the waveguide 5 to the waveguide 1 through the single hole A, and an electric dipole exists at the center point of the single hole A. A similar distribution is formed. On the other hand, a magnetic field distribution similar to the presence of a magnetic dipole at the center point of the single hole A is also formed by the magnetic field leaking from the waveguide 5 to the waveguide 1. As an effect of superimposing these electric dipoles and magnetic dipoles, a microwave propagating in only one direction in the waveguide 1 is excited.

FIG. 13 is a schematic diagram showing a directional coupler coupled by Bethe holes. As illustrated in the figure, when the waveguide 5 and the waveguide 1 are coupled via the Bethe hole A, the electric dipole is proportional to the TE ₁₀ mode electric field of the waveguide 5 and perpendicular to the hole. A magnetic dipole in the opposite direction in proportion to the magnetic field of the child and the waveguide 5 is formed in the waveguide 1. The wave due to the electric dipole and the wave due to the magnetic dipole have the same phase in one direction of the waveguide 1 and are added to each other, but are reversed and subtracted in the opposite direction. Therefore, the wave in the reverse direction can be made zero by adjusting the position of the hole.

  FIG. 14 is a schematic diagram showing a directional coupler coupled by two holes. That is, the waveguide 5 and the waveguide 1 are coupled by two small holes A and B separated by a distance L on the side wall or the H plane. Here, the distance L is defined by the above-described equation. A wave traveling in the waveguide 5 excites the waveguide 1 through these two small holes. At this time, the waves excited through the two small holes A and B proceed with the same amplitude and the same phase in the same direction as the wave traveling direction in the waveguide 5, but the same amplitude in the opposite direction. , They are out of phase and cancel each other. Therefore, only a wave in one direction is excited in the waveguide 1.

  FIG. 15 is a schematic diagram illustrating a directional coupler coupled by a cross-shaped slit. That is, the waveguide 5 and the waveguide 1 are orthogonal to each other, and one or a plurality of cross-shaped slits S are formed on the diagonal line of the overlapping surface. When the slit S is provided in this manner, the coupling by the electric field is so small that it can be ignored, and the coupling by the magnetic field becomes dominant. Then, a magnetic dipole is formed on the long axis of the slit by Ht and Hz of the waveguide 5, thereby exciting the waveguide 1 and causing directionality.

  FIG. 16 is a schematic diagram illustrating a directional coupler coupled by a loop. That is, the coaxial line 1 is coupled within the waveguide of the waveguide 5 by a loop, and the coupling from the waveguide 5 to the coaxial line 1 is performed by an electric field and a magnetic field passing through the loop. The wave excited by the electric field travels in the same direction in both directions of the coaxial line 1 with the same amplitude and phase. On the other hand, the current induced by the magnetic field is given by Faraday's electromagnetic sensitivity law, and waves traveling in both directions of the coaxial line 1 have the same amplitude but opposite phases. Therefore, when the wave due to the electric field and the wave due to the magnetic field are appropriately combined, the output of one of the waves traveling along the coaxial line 1 becomes zero, and the directionality can be obtained.

  Specific examples of directional couplers that can be used in the present invention have been given above with reference to FIGS. However, the present invention is not limited to those using these specific examples. For example, in addition to these, the introduction waveguide 70 and the annular traveling wave resonator 10 are coupled to each other, and a slot is provided in the common wall, and further, a mode adjusting conductor rod (post) is provided in the slot. Any other directional coupler may be used, and any one that provides directionality for the excitation of the annular traveling wave resonator 10 is included in the scope of the present invention.

  Next, a specific example of the plasma generator of the present invention will be described.

  FIG. 17 is a schematic cross-sectional view illustrating the structure of the plasma processing apparatus of the present invention. This apparatus includes a processing chamber 60, a waveguide (transmission window) 54 made of a flat dielectric plate provided on the upper surface of the processing chamber 60, and an introduction waveguide provided outside the waveguide 54. It has a tube 52 and an annular traveling wave resonator 10 coupled via a coupler 40. The processing chamber 60 includes a stage 16 for mounting and holding a workpiece W such as a semiconductor wafer in a processing space below the waveguide 54.

  The processing chamber 60 can maintain a reduced pressure atmosphere formed by the evacuation system E, and is appropriately provided with a gas introduction pipe (not shown) for introducing a processing gas into the processing space.

  For example, when performing an etching process on the surface of the workpiece W using this plasma processing apparatus, first, the workpiece W is placed on the stage 16 with the surface facing upward. . Next, after the processing space is depressurized by the vacuum exhaust system E, an etching gas as a processing gas is introduced into the processing space. Thereafter, in a state where the atmosphere of the processing gas is formed in the processing space, for example, a 2.45 GHz microwave is introduced into the annular traveling wave resonator 10 through a directional coupler from an introduction waveguide (not shown), A traveling wave in one direction is excited in the annular traveling wave resonator 10, and the traveling wave is resonated. As a result, a microwave wave field is formed in the annular traveling wave resonator 10 by a uniform and continuous traveling wave.

  The microwave wave field is distributed to the introduction waveguide 52 by the coupler 40 and radiated toward the waveguide 54. The waveguide 54 is made of a dielectric such as quartz or alumina, and the microwave M propagates on the surface of the waveguide 54 and is radiated to the processing space in the chamber 60. The plasma P of the processing gas is formed by the energy of the microwave M radiated into the processing space in this way. When the electron density in the generated plasma becomes equal to or higher than the density (cutoff density) that can shield the microwave M supplied through the waveguide 54, the microwave is processed from the lower surface of the waveguide 54 in the chamber. A microwave standing wave is formed until a certain distance (skin depth) d enters the space, and a microwave standing wave is formed.

  Then, the microwave reflection surface becomes a plasma excitation surface, and the stable plasma P is excited on this plasma excitation surface. In the stable plasma P excited on this plasma excitation surface, ions and electrons collide with the molecules of the processing gas, thereby causing excited active species (plasma generation) such as excited atoms, molecules, and free atoms (radicals). Product) is generated. These plasma products diffuse in the processing space as indicated by arrow A and fly to the surface of the workpiece W to be subjected to plasma processing such as etching, ashing, thin film deposition, surface modification, and plasma doping. Can do.

  According to the present invention, a continuous and high-intensity microwave generated by a resonant traveling wave formed in the annular traveling wave resonator 10 is distributed by the coupler 40 and introduced into the chamber 60. A large area of uniform and high density plasma can be formed. As a result, it is possible to perform plasma processing on a large-area workpiece to be performed uniformly and at high speed.

  Furthermore, by keeping the coupling coefficient of the coupler 40 low, even if the plasma impedance changes, fluctuations in the resonance conditions of the annular traveling wave resonator 10 and fluctuations in the distribution balance among the plurality of couplers 40 are reduced. Can be suppressed. As a result, it is possible to always stably perform a large area plasma treatment.

Next, a specific example of a configuration for making the plasma density more uniform in the plasma generator of the present invention will be described.
For example, in the case of the plasma generator described above with reference to FIG. 9, there may be a difference in generated plasma density between the plurality of applicators 50 that are close to and far from the introduction waveguide 70. Typically, the applicator 50 close to the introduction waveguide 70 may have a high plasma density, and the applicator 50 far from the introduction waveguide 70 may have a low plasma density. In such a case, the degree of coupling of the applicator 50 close to the introduction waveguide 70 is low, and if the degree of coupling is set high in the applicator 50 far from the introduction waveguide 70, the plasma density can be made uniform. is there.

The microwave M introduced into the introduction waveguide 70 is introduced into the annular traveling wave resonator 10 via the directional coupler 20 to form a traveling wave M4. At this time, the power is balanced so that the attenuation amount of the microwave propagating through the annular traveling wave resonator 10 and the power introduced into the annular traveling wave resonator 10 through the directional coupler 20 are equal, and When the directional coupler 20 having high directivity is used, only the traveling wave M4 is excited in the annular traveling wave resonator 10, and the power is output from the output port of the directional coupler 20 to the fixed short plunger 73. Not.

FIG. 18 is a conceptual diagram showing a microwave introduction part to the annular traveling wave resonator in the present embodiment.
That is, the introduction waveguide 70 and the annular traveling wave resonator 10 are coupled by the directional coupler 20. The output port of the directional coupler 20 is terminated by a fixed short plunger 73 so that a reflected wave is generated.

  The microwave M introduced into the introduction waveguide 70 is introduced into the annular traveling wave resonator 10 via the directional coupler 20 to form a traveling wave M4. At this time, the power is balanced so that the attenuation amount of the microwave propagating through the annular traveling wave resonator 10 and the power introduced into the annular traveling wave resonator 10 through the directional coupler 20 are equal, and When the directional coupler 20 having high directivity is used, only the traveling wave M4 is excited in the annular traveling wave resonator 10, and power is output from the output port of the directional coupler 20 to the fixed short plunger 20. Not.

On the other hand, when the power balance between the power introduced into the annular traveling wave resonator 10 and the attenuation amount of the microwave is slightly shifted or the directionality of the directional coupler 20 is slightly decreased, the directional coupler A slight output is distributed from the 20 output ports to the fixed short plunger 73, and the reflected waves R1 and R2 are excited. The reflected wave R1 propagates through the introduction waveguide 70, but the reflected wave R2 is excited in the direction opposite to the traveling wave M4 in the annular traveling wave resonator 10.
That is, a weak reflected wave R2 in the opposite direction to the traveling wave M4 is excited in the annular traveling wave resonator 10.

FIG. 19 is a conceptual diagram showing an applicator in which the output is variable using such a reflected wave R2.
FIG. 20 is a schematic diagram showing a specific example of a cross-sectional structure taken along the line AA of the applicator portion.
FIG. 21 is a schematic diagram showing a cross-sectional structure taken along line BB in FIG.

  That is, power is output from the annular traveling wave resonator 10 to the applicator 50 via the directional coupler 40. The dummy output port 53 of the directional coupler 10 is provided with a variable short plunger (phase difference adjusting means) 58. As described above with reference to FIG. 18, the traveling wave M <b> 4 and the weak reflected wave R <b> 2 are excited in the annular traveling wave resonator 10. The traveling wave M4 is output from the directional coupler 40 as it is to the introduction waveguide 52 of the applicator 50, and the reflected wave R2 is output from the dummy output port 53 and reflected by the variable short plunger 58 to introduce and guide the applicator. It is supplied to the wave tube 52. Therefore, the power of the microwave radiated from the applicator 50 is determined by combining the traveling wave M4 and the reflected wave R2. However, the traveling wave M4 enters the applicator 50 as it is from the directional coupler 40, whereas the reflected wave R2 is reflected by the variable short plunger 58 and then enters the applicator 50. A phase difference occurs. This phase difference can be controlled by adjusting the variable short plunger 58. For example, in the case of the specific examples shown in FIGS. 20 and 21, the variable short plunger 58 is movable in the vertical direction, and the phase of the reflected wave R2 can be controlled by adjusting its height.

  According to this specific example, a weak reflected wave is excited in the annular traveling wave resonator 10 in this manner, and the phase of the reflected wave is controlled using the directional coupler and the variable short plunger to the applicator. By making it output, the output can be adjusted independently for every applicator.

Hereinafter, an embodiment of the plasma generator described above with reference to FIGS. 18 to 21 will be described. FIG. 22 is a schematic plan view for explaining the arrangement of the applicators in the plasma generator of this embodiment.
FIG. 23 is a schematic cross-sectional view showing the configuration of the plasma generator of this example.
In this embodiment, the processing chamber 60 having a substantially cylindrical inner space with a diameter of 40 centimeters is used. Then, the annular traveling wave resonator 10 was disposed above the processing chamber 60, and six applicators 50 coupled via the directional coupler 40 were attached to the upper lid of the processing chamber 60 at equal intervals. Each applicator 50 is provided with a variable short plunger 58. Here, each of the six applicators 50 is numbered “No. 1” to “No. 6”. The first applicator 50 is disposed at a position farthest from the position where the microwave M is introduced by the introduction waveguide 70.

  On the stage 16 provided in the processing chamber 60, a wafer W having a diameter of 12 inches coated with a photoresist was placed. Then, the pressure of oxygen (O 2) in the processing chamber 60 is set to 15 pascals, the microwave M is introduced from the introduction waveguide 70, and ashing of the photoresist applied to the wafer W is performed. The distribution of ashing speed on W was measured. Here, the frequency of the introduced microwave M is 2.45 GHz and the output is 3 kW. The distance from the tip of the quartz waveguide 54 to the wafer W was 4.2 centimeters.

24 and 25 are schematic views illustrating the ashing speed distribution when the power distribution of the six applicators is not uniform.
That is, in the case illustrated in FIG. 24, the ashing speed in the vicinity of the first applicator 50 (the applicator farthest from the introduction waveguide 70) is much higher than the ashing speed in the vicinity of the other five applicators. Very low. That is, it can be seen that the microwave output from the first applicator 50 is much lower than the outputs from the other five applicators.

On the other hand, the ashing speed distribution illustrated in FIG. 25 is obtained by changing only the variable short plunger 58 of the first applicator 50 from the state described above with reference to FIG. The ashing speed in the vicinity of the first applicator is very high compared to the ashing speed in the vicinity of the other five applicators.
That is, comparing FIG. 24 with FIG. 25, it can be seen that the ashing speed can be controlled in a very wide range by adjusting the variable short plunger 58. In other words, according to the present embodiment, the microwave introduction power can be controlled independently for each applicator within a very wide range according to the arrangement of the equipment, process conditions, or usage history, and an extremely wide adjustment margin can be obtained. It is done.

FIG. 26 is a schematic diagram showing the distribution of the ashing speed obtained when the variable short plunger 58 of the first applicator is adjusted to the optimum position.
In the vicinity of the first to sixth applicators, a substantially uniform ashing speed is obtained, and it can be seen that a uniform plasma treatment can be performed over a large area.
22 to 26 show specific examples in which six applicators are provided and variable short plungers 58 are provided in each of them, but the present invention is not limited to this. That is, the number of applicators may be greater than at least 6, and all of these applicators may be provided with variable short plungers, or only some of these applicators may have variable short plungers. A plunger may be provided.

  The embodiments of the present invention have been described with reference to specific examples. However, the present invention is not limited to these specific examples.

  For example, the elements such as the introduction waveguide, the annular traveling wave resonator, the applicator, or the directional coupler used in the present invention are not limited to the illustrated shapes and sizes, but the cross-sectional shape, wall thickness, The shape and size of the opening are appropriately changed to obtain the same function and effect, and are included in the scope of the present invention.

  The introduction waveguide does not need to be a straight tube, and the annular traveling wave resonator does not need to be a perfect ring.

  Also, the shape and size of the plasma generation chamber, or the positional relationship with the annular traveling wave resonator and applicator are not limited to those shown in the figure, and should be appropriately determined in consideration of the contents and conditions of the plasma treatment. Can do. Further, the annular traveling wave resonator may be attached to the lower surface instead of the upper surface or the side surface of the plasma generation chamber, or a combination thereof. In other words, a plurality of annular traveling wave resonators may be attached to the plasma generation chamber. This makes it possible to form a large-area plasma having a uniform or predetermined density distribution according to the shape and size of the object to be processed.

  Furthermore, in the above-described specific examples, only the main configuration of the plasma generation unit has been described. However, the present invention includes all plasma processing apparatuses having such a plasma generation unit, for example, an etching apparatus and an ashing apparatus. Any plasma processing apparatus realized as a thin film deposition apparatus, a surface treatment apparatus, a plasma doping apparatus, and the like is included in the scope of the present invention.

1 Waveguide (coaxial line)
5 Waveguide 10 Annular Traveling Wave Resonator 16 Stage 20 Directional Coupler 21 Input Port 22 Output Port 40 Directional Coupler 42, 44 Coupler 50 Applicator 52 Introduction Waveguide 53 Dummy Output Port 54 Waveguide 58 Variable short plunger 60 Plasma generation chamber (processing chamber)
70 Introducing waveguides 72 and 74 Dummy loads 80 and 82 Power monitor 90 Phase adjuster 100 Waveguide 101 Waveguide 102 Slot 103 Introduction portion 503 Waveguide 521 Distribution block 522 Slot 523 Microwave 525 Wave M Microwave P Plasma W Workpiece

Claims (6)

A plasma generation chamber capable of maintaining an atmosphere depressurized from the atmosphere;
An introduction waveguide;
An annular resonator that resonates the traveling wave of the microwave;
A directional coupler for coupling the introduction waveguide and the annular resonator;
A plurality of couplers for distributing microwaves from the annular resonator;
A plurality of applicators coupled to each of the plurality of couplers and spaced apart from each other for introducing microwaves into the plasma generation chamber;
With
When the amplitude coupling coefficient of the directional coupler is C ₀ , the coupling coefficient of each of the plurality of couplers is C _i , and the propagation coefficient of the microwave that goes around the annular resonator is T,

By making it substantially hold,
Wherein the introduction waveguide via the directional coupler by exciting the annular cavity to form a traveling wave of the microwave in the annular resonator,
The plurality of applicators each have a waveguide formed of a dielectric material that introduces microwaves into the plasma generation chamber, and plasma can be generated by the microwaves introduced from the waveguide into the plasma generation chamber. A plasma generator characterized by that.   2. The amplitude coupling coefficient of each of the plurality of couplers is set to be low so that impedance to the microwave does not substantially change even if the electron density of the plasma changes. The plasma generator described.   3. The plasma generating apparatus according to claim 1, wherein a total value of power coupling coefficients of each of the plurality of couplers is 20% or less.   2. The pipe line and internal parts of the annular resonator are formed so that a round-trip phase difference of the traveling wave propagating through the inside is substantially equal to an integral multiple of 360 degrees. The plasma generator as described in any one of -3.   5. The plasma generation apparatus according to claim 1, wherein an n coupling coefficient between the applicator and the plasma is larger than a coupling coefficient between the coupler and the annular resonator. Comprising the plasma generator according to any one of claims 1 to 5,
A plasma processing apparatus characterized in that a plasma processing of an object to be processed can be performed by the plasma generated by the microwave introduced through the applicator.

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