WO2004032219A1

WO2004032219A1 - Plasma processing system

Info

Publication number: WO2004032219A1
Application number: PCT/JP2003/012792
Authority: WO
Inventors: Shigeru Kasai; Yuki Osada; Takashi Ogino
Original assignee: Tokyo Electron Limited
Priority date: 2002-10-07
Filing date: 2003-10-06
Publication date: 2004-04-15
Also published as: JP4159845B2; CN1692476A; JP2004128385A; CN101320679A; KR100719639B1; CN100416772C; KR20050050116A; CN101320679B

Abstract

A plasma processing system comprising a chamber for containing a substrate being processed, a unit for supplying processing gas into the chamber, and a unit for introducing a microwave for generating plasma into the chamber. The microwave introducing unit comprises an oscillator delivering a plurality of microwaves having specified outputs, and an antenna section having a plurality of antennas transmitting the plurality of microwaves delivered from the microwave oscillator.

Description

Description Plasma processing equipment Technical field

The present invention relates to a plasma processing apparatus that performs a plasma process such as etching on a substrate to be processed. Background technology

In the manufacturing process of semiconductor devices and liquid crystal display devices, in order to perform plasma processing such as etching and film formation on substrates to be processed, such as semiconductor wafers and glass substrates, plasma etching equipment, plasma CVD film deposition equipment, etc. The plasma processing apparatus is used.

As a method of generating plasma in a plasma processing apparatus, a processing gas is supplied into a chamber in which parallel plate electrodes are arranged, and a predetermined power is supplied to the parallel plate electrodes to generate plasma by capacitive coupling between the electrodes. The method accelerates the electrons by an electric field generated by a microwave introduced into the chamber and a magnetic field generated by a magnetic field generator disposed outside the chamber, and the electrons collide with neutral molecules of the processing gas to generate neutral molecules. There is known a method of generating plasma by ionizing a gas.

In the latter method using the magnetron effect of an electric field generated by a microwave and a magnetic field generated by a magnetic field generator, a microwave having a predetermined power is supplied to an antenna disposed in a chamber through a waveguide Z coaxial tube. Microwaves are radiated from the antenna to the processing space in the chamber.

FIG. 8 is an explanatory diagram showing a schematic configuration of a conventional general microwave introduction device. The microwave introduction device 90 generally includes a magnetron 91 a that outputs a microwave adjusted to a predetermined power and a microwave generation power supply 91 b that supplies an anode current of a predetermined frequency to the magnetron 91 a. A microwave oscillator 91, an antenna 94 that radiates the microwave output from the microphone mouth wave oscillator 91 to the processing space in the chamber, and a reflection from the antenna 94 to return to the microwave oscillator 91. An isolator 92 that absorbs the microphone mouth wave, and a matcher 93 that has a tuner that matches the antenna 94 so as to reduce the power of the reflected microwave and that connects the waveguide to the coaxial waveguide. (See, for example, Japanese Patent No. 2722070 and Japanese Patent Application Laid-Open No. 8-306319). Summary of the invention

However, the microwave oscillator 91 using the magnetron 91a has a problem that the life of the magnetron 91a is short, about half a year, so that the equipment cost and the maintenance cost are increased. The oscillation stability of the magnetron 91a was about 1%, and the output stability was as large as about 3%. Therefore, it was difficult to transmit a stable microphone mouth wave.

The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a plasma processing apparatus including a long-life microwave oscillator. Another object of the present invention is to provide a plasma processing apparatus including a microwave oscillator capable of stably supplying a microwave.

As means for solving such a problem, the present inventors have previously proposed a plasma processing apparatus that amplifies a microwave to a predetermined output using a semiconductor amplifier (Japanese Patent Application No. 2002-28). 8769, hereinafter referred to as “prior application”). FIG. 7 is an explanatory diagram showing a schematic configuration of a microwave introduction device provided with a microwave oscillator using a semiconductor amplifying element according to the prior application.

The microwave introduction device 80 includes a microwave oscillator 80 a that oscillates microwaves of a predetermined power, and a microwave oscillator 80 a from the antenna 87 to the microwave oscillator 80 a among the microwaves output from the microwave oscillator 80 a. An isolator 85 that absorbs the reflected microwaves that are going to return, an antenna 87 that is provided in the chamber and oscillates the microphone mouth wave output through the isolator 85 toward the processing space of the chamber, and an antenna 87 And a matcher 86 that matches the antenna 87 so as to reduce reflected microwaves.

The microwave oscillator 80a includes a microwave generator 81 for generating microwaves and a plurality of microwaves output from the microwave generator 81 (four in FIG. 7). And the four soli- cers that amplify each of the four-path microphone mouth waves output from the splitter 82 to predetermined power individually. And a combiner 84 that combines microwaves amplified by the solid state amplifiers 83.

The microwave generator 81 includes a microwave generator (generator) 81 a for generating a microwave of a predetermined frequency (for example, 2.45 GHz), and a microwave generated by the microwave generator 81 a. And a variable attenuator 81b that attenuates the power of the wave to a predetermined level.

The solid-state amplifier 83 is composed of a sub-distributor 83 a that distributes the input microwave to a plurality of microphone mouth waves (a case where the microwave is distributed to four systems) and a sub-divider 83. a semiconductor amplifying element 83 b for amplifying the microwave output from a to a predetermined power, and a sub-combiner 83 c for synthesizing the amplified microwave output from each semiconductor amplifying element 83 b. Have.

According to such a microwave introduction device, since the semiconductor amplifying element 83b performs power amplification, the lifetime of the device is semi-permanent, and a microwave with stable output can be radiated into the chamber. it can.

However, in such a microwave introduction device 80, in addition to the impedance matching in the solid state pump 83, it is necessary to perform the impedance matching in the distributor 82 and the combiner 84. In the case of impedance mismatch, power loss can be large. In particular, in a plasma processing apparatus, for example, it is necessary to transmit a microwave of 2 to 3 kW to the antenna 87, and in the microwave introducing apparatus 80, such high-power microwaves are Must be synthesized in 4. For this reason, in the combiner 84 in particular, more precise impedance matching is required in order to suppress microwave power loss.

Furthermore, since the high-power microwave output from the combiner 84 is transmitted to the isolator 85, the isolator 85 also needs to be a large-sized device of several kilobits. Therefore, there arises a problem that the degree of freedom of an installation place of the isolator 85 is reduced and a problem that the isolator 85 itself becomes expensive. Furthermore, since the synthesized microwave is transmitted to the antenna 87 by one coaxial tube, the antenna is It is not possible to adjust the power distribution of the microwaves output from the antenna 87.

The present invention relates to these problems that occur in the microwave introduction device according to the above-mentioned prior application, namely, a problem of an increase in transmission loss, a problem of an increase in the size of a device for supplying microwaves, and a problem of radiated microwave power It solves the problem of non-adjustable distribution and.

According to the present invention, a chamber accommodating a substrate to be processed;

A gas supply device for supplying a processing gas into the chamber;

A microwave introduction device for introducing a microwave for plasma generation into the chamber;

With

The microwave introduction device,

A microwave oscillator that outputs a plurality of microwaves having a predetermined output,

An antenna unit having a plurality of antennas to which a plurality of microwaves output from the microwave oscillator are respectively transmitted;

have

A plasma processing apparatus characterized by the above-mentioned features.

According to the present invention, since each microwave is transmitted to each of the plurality of antennas constituting the antenna unit, it is not necessary to combine high-power microwaves on the transmission line up to the antenna unit. Therefore, since a combiner becomes unnecessary, it is possible to completely avoid the occurrence of power loss due to the combiner. Further, since the output of each microwave transmitted to each antenna unit can be reduced, it is not necessary to use a high power isolator. As a result, it is possible to avoid an increase in the size of the microwave oscillator. Further, a plurality of antennas constituting the antenna unit can be supplied with microwaves having different powers, whereby the output distribution of the microphone mouth wave radiated from the antenna unit can be adjusted.

Preferably, the microwave oscillator is a microphone mouth wave generator that generates a low-power microwave, a distributor that distributes the microwave generated from the microphone mouth wave generator to a plurality of microphone mouth waves, And a plurality of amplifier units for amplifying the microwave output from the distributor to a predetermined power, and output from the plurality of amplifier units. A plurality of microwaves are respectively transmitted to the plurality of antennas.

In this case, each of the plurality of amplifier units includes a variable attenuator that attenuates each microwave output from the distributor to a predetermined level, and amplifies the microwave output from the variable attenuator to a predetermined power. A solid-state amplifier, an isolator for separating reflected microwaves to be returned to the solid-state amplifier from microphone mouth waves output from the solid-state amplifier to the antenna, and adjusting the power of the reflected microwaves By adjusting the attenuation rate of each variable attenuator, it is possible to supply microwaves with different powers to a plurality of antennas, respectively. This makes it possible to adjust the distribution of plasma generated in the champer.

The isolator includes a dummy load that converts the reflected microwave into heat, and a circuit that guides the microwave output from the solid state amplifier to the antenna and guides the reflected microwave from the antenna to the dummy load. , May be

In this case: 1. Since the power of the microwave output from one solid-state amplifier is not extremely large, a small isolator can be used, and therefore the equipment cost can be reduced.

The solid-state amplifier includes: a sub-divider that distributes an input microwave to a plurality of microwaves; and a plurality of semiconductor amplifying elements that amplify a plurality of microphone mouth waves output from the sub-divider to predetermined power, respectively. And a synthesizer for synthesizing microwaves power-amplified by the plurality of semiconductor amplifying elements. As this semiconductor amplifying element, a power MOS FET, a GaAs FET, a GeSi transistor, or the like is preferably used.

Since the low-power microwave is amplified by the semiconductor amplifying element without using the magneto port, the life of the amplifier section can be made semi-permanent. As a result, equipment costs and maintenance costs can be kept low. Further, since the semiconductor amplifier has excellent output stability, it is possible to radiate microwaves having stable characteristics into the chamber. As a result, the state of plasma generation is maintained well, and Processing quality can be improved. Further, in this case, the output adjustment range of the amplifier section is as wide as 0 ° / ₀ to: L 0%, and the adjustment is easy.

The antenna section includes a circular antenna provided at the center, a plurality of substantially sector-shaped antennas surrounding the outside of the circular antenna, and a separation plate separating the circular antenna and the substantially sector-shaped antenna. Can be used. Each antenna may have a slow wave plate, a cooling plate, and a slot plate. It is preferable that the separation plate is a metal member and is grounded.

In this case, the slot plate of the circular antenna is provided with a first slot of a predetermined length on the circumference inside by λ g Z4 from the outer periphery of the circular antenna, and g / 2 from the first slot. Preferably, a second slot of a predetermined length is provided on each of the inner concentric circles. In addition, a third slot of a predetermined length is provided on the slot plate of the substantially fan-shaped antenna from the boundary between the substantially fan-shaped antennas; g / 4 inside and λ g Z 2 from the third slot. It is preferable that a fourth slot having a predetermined length is provided in the second slot. This allows the microphone mouth wave to be efficiently radiated into the chamber. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a sectional view showing a schematic configuration of a plasma etching apparatus according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a configuration of a microwave introduction device provided in the plasma etching device of FIG.

FIG. 3 is an explanatory diagram showing a planar structure of the antenna.

FIG. 4 is a schematic cross-sectional view showing the structure of the disk antenna.

FIG. 5 is a diagram illustrating an example of an equivalent circuit used for impedance matching. FIG. 6 is an explanatory diagram (smith chart) showing the impedance change during plasma ignition and during the process.

FIG. 7 is an explanatory diagram showing a schematic configuration of a microphone mouth wave introducing device provided with a microwave oscillator using a semiconductor amplifying element.

FIG. 8 is an explanatory diagram showing a configuration of a conventional microwave introduction device. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing a schematic configuration of a plasma etching apparatus 1 which is an example of a plasma processing apparatus. FIG. 2 is an explanatory diagram showing a more detailed configuration of the microwave introduction device 50 provided in the plasma etching device 1. The substrate to be processed in the plasma etching apparatus 1 is a semiconductor wafer W.

Plasma etching measures 1 consist of a chamber 11 for accommodating the wafer W and a chamber

A gas inlet 26 provided in 11 and a gas supply device 27 for supplying a processing gas for plasma generation (for example, chlorine (C 1 ₂ )) to the inside of the chamber 11 through the gas inlet 26. And an exhaust port 24 provided in the chamber 11, an exhaust device 25 for exhausting the inside of the chamber 11 through the exhaust port 24, and holding the wafer W in the chamber 11. A substrate holding stage 23, an air-core coil 21 for generating a magnetic field in a processing space 20 inside the chamber 11, and a microphone mouth wave introducing device 50 for supplying a microwave into the chamber 11 are provided. I have.

The microwave introduction device 50 includes a microwave oscillator 30 that outputs a plurality of microwaves having predetermined outputs (FIGS. 1 and 2 show four paths), and a microwave oscillator.

Antennas 13a, 13b · to which each microwave output from 30 is fed separately

And an antenna section 13 composed of 13 c · 13 d (13 d is not shown in FIG. 1).

The microwave oscillator 30 is composed of a microwave generator 31 that generates a low-power microwave, and a distributor 3 2 that distributes the microwave output from the microwave generator 31 to a plurality of microwaves (see FIG. 2 shows the case where the signal is divided into four), and a plurality of amplifiers 3 3 that amplify each microwave output from the distributor 32 to a predetermined power (four amplifiers 3 3 are shown in Figure 2) Is provided. The microphone mouth waves output from these four amplifier sections 33 are respectively supplied to feed points 60a'60b'60c.60d provided in antennas 13a to 13d, respectively. Transmitted (see Figure 3).

The microwave generator 31 generates a microwave having a predetermined frequency (for example, 2.45 GHz). Distributor 32 should minimize the microwave loss Then, the microphone mouth wave is distributed while impedance matching between the input side and the output side is maintained.

As shown in FIG. 2, each of the amplifier sections 33 includes a variable attenuator 41 for attenuating the microwave output from the distributor 32 to a predetermined level, and a predetermined output from the variable attenuator 41. A solid-state amplifier 42 that amplifies the power of the antenna and a microphone that is output from the solid-state amplifier 42 to each of the antennas 13a to 13d. It has an isolator 43 for separating the waves, and a matcher 44 for adjusting the power of the reflected microwave.

The variable attenuator 41 adjusts the power level of the microphone wave input to the solid state amplifier 42. Therefore, by adjusting the attenuation level in the variable attenuator 41, the power of the microwave output from the solid state amplifier 42 can be adjusted.

Each of the four amplifier sections 33 is individually provided with a variable attenuator 41. Therefore, the power of the microwaves output from the four amplifier sections 33 can be made different from each other by individually changing the attenuation rates of the variable attenuators 41. That is, in the microwave oscillator 30, the antennas 13a to 1

3d can be supplied with microwaves of different power. Thus, in addition to generating uniform plasma in the chamber 11, various distributions of plasma can be generated.

The solid-state amplifier 42 includes a sub-divider 42 a that distributes the input microwave to a plurality of microphone mouth waves (in FIG. 2, a case where the microwave is divided into four systems) and a sub-divider 42. Semiconductor amplifying device that amplifies microwaves output from a to predetermined power

42 b and a combiner 42 c for combining amplified microwaves output from each semiconductor amplifying element 42 b.

The sub distributor 42 has the same configuration as the distributor 32. As the semiconductor amplifying element 42b, for example, a power MOSFET is used. The maximum power of the microwave output from one semiconductor amplifying element 4 2 b is, for example, 100 W to 150 W _c. On the other hand, the microwave that must be supplied to the antenna unit 13 The total power of the wave is Generally, it is 100 000 to 300 OW. Therefore, the attenuation rate of the variable attenuator 41 of each amplifier unit 33 can be adjusted so that the average mouth wave of 250 W to 75 OW is transmitted to the antennas 13a to 13d. .

The combiner 42c combines the microwaves output from the semiconductor amplifying elements 42b while maintaining impedance matching. At this time, a circuit of a Wilkinson type, a branch line type, a sorter balun type, or the like can be used as the matching circuit. The microwave output from the solid state amplifier 42 is sent to each of the antennas 13a to 13d constituting the antenna unit 13 through the isolator 43 and the matcher 44. At this time, some of the microwaves return (reflect) from the antennas 13a to l3d to the solid state amplifier 42. The isolator 43 has a circulator 43 a and a dummy load (coaxial terminator) 43 b, and the circulator 43 a is connected to the solid state amplifier 42 from the antennas 13 a to 13 d. The reflected microwave which tries to go backward is directed to the dummy load 4 3 b. Dami bit by bit 43 b converts the reflected microphone mouth waves guided by the circulator 43 a into heat.

As described with reference to FIG. 7, when microwaves amplified to a predetermined power by the solid state amplifier 83 are combined and then passed through the isolator 84, the isolator 84 has a capacity of several kilobytes. It is necessary to withstand electric power, and the isolator 84 itself becomes large and expensive. However, in the microwave microphone 30 according to the present embodiment, the microwaves amplified to a predetermined power by the solid state amplifier 42 are passed through the isolator 43 without being synthesized, and the solid state amplifiers 4 2 Since the power of each microwave output from is not extremely large, a small isolator 43 can be used, and the device cost can be reduced.

The matcher 44 has a tuner that matches the antennas 13a to 13d so as to reduce the reflected microwave guided to the dummy load 43b. The microwaves are passed from the matcher 44 to the feed points 60a to 60d provided in the antennas 13a to l3d through the coaxial outer tube conductor 16a and the coaxial inner tube conductor 16b (Fig. See 1). The coaxial inner tube conductor 16 b is connected to the antenna 13 a to l 3 d side. The end portion has a tapered portion 22 for suppressing / reducing microwave reflection.

FIG. 3 is an explanatory diagram showing the structure of the antenna unit 13 in a plan view. The disc-shaped antenna section 13 includes a circular antenna 13 a provided at the center, three substantially fan-shaped antennas 13 b to l 3 d surrounding the outer circumference of the antenna 13 a, and each antenna 13 a to l 3 d, and a separation plate 19. In other words, the antenna section 13 has a structure in which a conventional disk-shaped antenna is divided into four antennas 13a to 13d by the separation plate 19. The power supply points 60a to 60d (the mounting portions of the coaxial outer tube conductor 16a and the coaxial inner tube conductor 16b) are provided for each of the antennas 13a to l3d. I have.

As shown in FIG. 1, the antenna 13a is composed of a metal slot plate 14a in which a slot (not shown in FIG. 1) for emitting microwaves is formed at a predetermined position, and aluminum nitride. (A 1 N) and the like. Similarly, the antennas 13b to 13d each include a slot plate 14b in which a slot (not shown in FIG. 1) is formed and a slow wave plate 17b. Each of the slow wave plates 17a and 17b also serves as a cooling plate. Further, the antenna section 13 has a microwave transmitting insulating plate 15 for preventing direct contact between the slot plates 14a and 14b and the plasma generated in the processing space 20.

It is preferable that the separating plate 19 is a metal member and is grounded. The microphone mouth wave supplied to the antennas 13a to 13d through the power supply points 60a to 60d is rotated 180 degrees in phase by the separating plate 19 and totally reflected. That is, there is no microwave movement between the antennas 13a to 13d. Each of the antennas 13a to 13d independently emits microwaves to the processing space 20. Due to the reflection of the microwaves by the separating plate 19, standing waves are formed on the slow wave plates 17a and 17b. Therefore, if elongated slots perpendicular to the traveling direction of the standing wave are formed at the positions of the slot plates 14a and 14b corresponding to the antinodes of the standing wave, these slots can be efficiently used. Microphone Mouth waves can be emitted into the processing space 20.

FIG. 3 shows the slots 6 1 a-61 b provided on the slot plate 14 a of the antenna 13 a and the slots provided on the slot plate 14 b of the antennas 13 b-l 3 d. The positions of 6 1 c and 6 1 d are also listed. In FIG. 3, the slots 61 a to 61 d are indicated by solid lines for convenience, but the slots 61 a to 61 d are actually holes having a predetermined width.

As shown in FIG. 3, in the circular antenna 13 a, the wavelength of the microwave is i, the specific inductivity of the slow wave plates 17 a and 17 b is _£ r, and: / ^ r ¹ , ² , a slot 61 a of a predetermined length is provided on a concentric circle inside by an amount of Ig / 4, and is abbreviated from this slot 61 a. It is preferable that a slot 61b of a predetermined length is provided on the inner concentric circle (only for g / 2). In addition, in the substantially fan-shaped antennas 13b to 13d, a slot 61c of a predetermined length is provided inward from the boundary between the antennas 13b to 13d by approximately gZ4. c. Abbreviation of force; It is preferable to provide a slot 61 d of a predetermined length inside by g / 2. Such positions of the slots 61a to 61d almost coincide with the positions of the antinodes of the standing wave described above.

The microwaves radiated from the slots 61 a to 61 d formed in the slot plates 14 a and 14 b pass through the microwave transmission insulating plate 15 and reach the processing space 20, where the processing space is processed. A microwave electric field is formed in 20. At the same time, when the air-core coil 21 is operated to generate a magnetic field in the processing space, the plasma can be efficiently generated by the magnetron effect. However, the air-core coil 21 is not always necessary. Plasma can be generated only by the microwaves radiated from the antenna 13.

According to the plasma etching apparatus 1 of the present embodiment, in order to stable microwave power into Therefore treatment space 2 0 in a microwave introduction device ⁵ 0 may be supplied in a stable manner the plasma is generated in the processing spatial 20 As a result, the processing quality of the wafer W is improved. Also, by giving a distribution to the radiated microwave power, a plasma having a distribution can be generated. For example, processing can be performed with different plasma densities at the center and the outer periphery.

By the way, the outer diameter of the entire antenna 13, the shape of each of the antennas 13 a to 13 d, and the position of each slot are determined by the method used to design a general disk-shaped antenna. Can be referred to. Therefore, the disk antenna is described below. The design method will be described briefly.

FIG. 4 is a schematic sectional view of the disk-shaped antenna 70. The disc-shaped antenna 70 includes a slot plate 71, a slow wave plate 72, a cooling plate 73, and a coaxial tube 74. The cooling plate 73 covers the outer periphery of the slow wave plate 72 and reflects the microwaves reaching the periphery of the slow wave plate 72 inward.

The slow wave plate 72 has a flat ring shape with an inner diameter of 2 Xr, an outer diameter of 2 XR, and a thickness of h. Defining λ 8 = _£ r ^1/2 , where λ is the wavelength of the microwave and ε r is the specific induction factor of the slow wave plate 72, the width L (= R—r) of the slow wave plate 72 Is preferably substantially an integral multiple of λg. In this case, the periphery of the slow wave plate 72 becomes a node of the standing wave, from the periphery of the slow wave plate 72; on the concentric circle inside by g / 4, and further from this circle; The concentric circle corresponds to the position of the antinode of the standing wave. It is preferable that the position of the slot in the slot plate 71 is adjusted to the position of the antinode of the standing wave. Thus, even if the characteristic impedances of the coaxial waveguide 74 and the slow wave plate 72 do not match, the power of the reflected microwave returning from the antenna 70 to the matcher can be suppressed to a small level.

The thickness h of the slow wave plate 72 can be obtained as follows. For example, when WX-39D is used as the coaxial waveguide 74, the inner diameter of the slow wave plate 72 is 2r = 38.8 mm. The characteristic impedance of the coaxial waveguide 74 is usually 50 Ω, while the characteristic impedance Z o of the parallel plate line is given by the following equation (1). Therefore, the thickness h of the slow wave plate 72 can be obtained as in the following equation (2). Here, ε is the average dielectric constant of aluminum nitride, and is the magnetic permeability of aluminum nitride. Here, since aluminum nitride is a dielectric material (insulating material), the relative magnetic permeability (^ r) is set to 1.

h β.h h 3 7 7

Z o =-3 7 7 (1)

2 π r 2 π r 2 π rrh = — ~ -x3 8.8x3.1 4x5 0 = 46.83 (mm) ' Next, a method of impedance matching in the antenna 70 will be described. In the circuit shown in Fig. 5, if the power supply voltage is Vg, the characteristic impedance of the line is Zo, and the load impedance is Ze, the voltage Vo at the load point is expressed by the following equation (3), and the reflection coefficient Γ is It is given by the following equation (4).

Z e— Z o

V o = Vg (3)

Z e + Ζ ο

Ζ e—n ο

Γ (4)

Ζ e + ο ο In order for the transmitted microwave energy to be effectively consumed by the load, it is necessary to set Ze = Zo. That is, it is necessary to match the combined impedance of the load and the matcher to the characteristic impedance of the transmission line. However, in order to ignite the plasma, the ignition voltage V s is represented by the following equation (5), which is the relational expression between the pressure P and the gap (discharge distance) L, according to the law of Paschen.

V s = f (pL) (5)

From equation (5), once the gap L is determined, the ignition voltage is uniquely determined. From equation (3), if Ze> Zo, the voltage Vo at the load point can be increased. Therefore, for example, in order to reduce the process time, as shown in the Smith chart of FIG. 6, the impedance is changed from the point A to the center point O through the inductive region so that an appropriate inductive reflection occurs at the time of plasma ignition. Should be maintained at the center point O (impedance matching position) during the process after plasma ignition.

The embodiments of the present invention have been described above, but the present invention is not limited to such embodiments. For example, the circuit configuration of the microwave oscillator 30 and the circuit configuration of the solid state amplifier 42 are not limited to the configuration shown in FIG. 2, and various modifications are possible. For example, if it is not necessary to provide a non-uniform distribution in the microwaves radiated from the antenna section 13, the microwave radiating areas of the antennas 13 a to l 3 d are made equal and each amplifier section 3 3 A structure in which a variable attenuator is provided between the microwave generator 31 and the distributor 32 without providing the variable attenuator 41 can be adopted. Thereby, the number of components of the variable attenuator can be reduced.

When transmitting microwaves having different powers to the antennas 13a to 13.d, it is also possible to use an amplifier section having a solid-state amplifier equipped with different numbers of semiconductor amplifying elements. is there. For example, for the antenna 13a, an amplifier unit having a solid state amplifier having four semiconductor amplifying elements is used to transmit a microphone aperture wave of 60 OW, while the antenna 13b to For 13 d, an amplifier unit having a solid-state amplifier having two semiconductor amplifying elements 42 for transmitting microwaves of 300 W can be used. The antenna section 13 is not limited to the form composed of the four antennas 13a to 13d, but may be composed of more or less antennas. Also, the shape of the antenna is not limited to a circle or a substantially fan shape as shown in FIG. If the antenna section is composed of more antennas, it is necessary to reduce the number of amplifier sections. However, since the power of the microphone mouth wave output from each amplifier section is further reduced, the amplifier section is further downsized. can do.

In the above description, the etching process is taken as the plasma process. However, the present invention can be applied to other plasma processes such as a plasma CVD process (a film forming process and a film modification of an oxynitride film) and an ashing process. Can be. In this case, an appropriate processing gas may be supplied into the chamber 11 according to the processing purpose. The substrate to be processed is not limited to the semiconductor wafer W, and may be an LCD substrate, a glass substrate, a ceramic substrate, or the like.

Claims

The scope of the claims

1. Accommodate the substrate to be processed

A gas supply device for supplying a processing gas into the chamber;

With

The microwave introduction device,

A microphone mouth wave oscillator that outputs a plurality of microphone output waves of a predetermined output,

have

A plasma processing apparatus characterized by the above-mentioned.

2. The microwave oscillator comprises:

A microwave generator for generating low-power microwaves,

A distributor that distributes a microphone mouth wave generated from the microphone mouth wave generator to a plurality of microphone mouth waves;

A plurality of amplifiers for amplifying each microwave distributed by the distributor to a predetermined power;

Has,

A plurality of microwaves output from the plurality of amplifier units are respectively transmitted to the plurality of antennas

2. The plasma processing apparatus according to claim 1, wherein:

3. Each of the plurality of amplifier units includes:

A variable attenuator for attenuating each microwave output from the distributor to a predetermined level;

A solid-state amplifier that amplifies microwaves output from the variable attenuator to a predetermined power. A single-state amplifier,

An isolator for separating reflected microwaves returning to the solid-state amplifier from microwaves output from the solid-state amplifier to the antenna;

A matcher for adjusting the power of the reflected microwave;

have

3. The plasma processing apparatus according to claim 2, wherein:

4. The isolator is

A dummy load that converts the reflected microphone mouth waves into heat;

A circulator for guiding microwaves output from the solid state amplifier to the antenna, and guiding reflected microwaves from the antenna to the dummy load.

4. The plasma processing apparatus according to claim 3, wherein:

5. The solid state amplifier is

A sub-divider for distributing an input microwave to a plurality of microwaves,

A plurality of semiconductor amplifying elements for amplifying a plurality of microwaves output from the sub-divider to a predetermined power, respectively;

Synthesizing a microwave that has been power-amplified by the plurality of semiconductor amplifying elements;

have

5. The plasma processing apparatus according to claim 3, wherein:

6. The semiconductor amplifying element is composed of a power MOS FET or a GaAs FET or a GeSi transistor.

6. The plasma processing apparatus according to claim 5, wherein:

7. Each of the plurality of antennas A slow wave plate,

A slot plate,

have

7. The plasma processing apparatus according to claim 1, wherein:

8. The antenna section

A circular antenna provided in the center,

A plurality of substantially sector-shaped antennas surrounding the outside of the circular antenna;

A separation plate for separating the circular antenna and the plurality of substantially fan-shaped antennas.

8. The plasma processing apparatus according to claim 7, wherein:

9. The separation plate is a metal member and is grounded

9. The plasma processing apparatus according to claim 8, wherein:

10 · When the wavelength of the microphone mouth wave is λ t, the relative permittivity of the slow wave plate is ε r, and λ g is defined as: / ε r ^1/2 ,

The slot plate of the circular antenna is provided with a first slot of a predetermined length on the inner circumference only from the outer periphery of the circular antenna: gZ4, and from the first slot; A second slot of a predetermined length is provided on the concentric circle,

The slot plates of the plurality of substantially fan-shaped antennas each have a third slot of a predetermined length provided on the inner side by L g / 4 from the boundary between the substantially fan-shaped antennas. 10. The plasma processing apparatus according to claim 8, wherein a fourth slot having a predetermined length is provided inside each two.

1 1. A magnetic field generator for generating a magnetic field is further provided in the chamber.

The magnetron effect is caused by the electric field generated by the microwave introduced into the chamber and the magnetic field generated by the magnetic field generator. Is

The plasma processing apparatus according to any one of claims 1 to 10, wherein: