JP2016173924A - Tuner and microwave plasma source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tuner capable of ensuring a required matching range even if a slug moving shaft is thin, and to provide a microwave plasma source having such a tuner.SOLUTION: A tuner includes a first slug moving section 51 having a power supply section 64, a first slug 63 constituting a coaxial transmission path consisting of a first outer conductor 61 and a first inner conductor 62, and moving between the first outer conductor 61 and the first inner conductor 62, and a first slug moving shaft 65 provided in the first inner conductor 62, and having the first slug moving shaft 65 for moving the first slug, and a second slug 73 having an output end for outputting microwaves to a planar antenna 101, and constituting a coaxial transmission path consisting of a second outer conductor 71 and a second inner conductor 72, and moving between the second outer conductor 71 and the second inner conductor 72, and including a second slug movement section 52 having a second slug moving shaft 75 provided in the second inner conductor 72. The slug movable ranges of the first slug moving section 51 and the second slug movement section 52 are the 1/2 wavelength of microwaves.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a tuner and a microwave plasma source that perform automatic impedance matching in a microwave plasma processing apparatus.

  In the manufacturing process of a semiconductor device or a liquid crystal display device, plasma processing such as a plasma etching apparatus or a plasma CVD film forming apparatus is performed in order to perform a plasma process such as an etching process or a film forming process on a target substrate such as a semiconductor wafer or a glass substrate. A device is used.

  Recently, as such a plasma processing apparatus, an RLSA (registered trademark) microwave plasma processing apparatus capable of uniformly forming high-density and low-electron temperature plasma has attracted attention (for example, Patent Document 1).

  The RLSA (registered trademark) microwave plasma processing apparatus is provided with a planar antenna having a number of slots formed in a predetermined pattern at the top of a chamber, and radiates a microwave guided from a microwave generation source from the slot of the planar antenna. In addition, the gas is radiated into a chamber held in a vacuum through a microwave transmission plate made of a dielectric material provided under the dielectric, and the gas introduced into the chamber is converted into plasma by the microwave electric field. An object to be processed such as a semiconductor wafer is processed by the formed plasma.

  There is also a microwave plasma processing apparatus having a microwave plasma source that divides microwaves into a plurality of channels and guides the microwaves into the chamber through the plurality of antenna modules having the planar antenna and spatially synthesizes the microwaves in the chamber. It has been proposed (Patent Document 2).

  In this type of microwave plasma processing apparatus, a tuner is required to match (tune) the impedance of the load (plasma). As a tuner, a slag tuner is known in which a pair of slags are movably provided in a coaxial transmission line, and impedances are matched by moving them. Patent Document 3 discloses that, in a slag tuner, when the wavelength of the microwave in the tube is λ, the pair of slags are moved within a length range of (½) λ while maintaining the same interval, and By controlling the movement of the slag so that either one of the pair of slags is moved within the length range of (1/4) λ with respect to the other, the total movement range of the pair of slags is (3/4) A technique is disclosed that can perform impedance matching in all regions on the Smith chart while being compact with λ.

  On the other hand, in Patent Document 4, two slag moving shafts (lead screws) made of screw rods for moving a pair of slags are provided inside the inner conductor of the coaxial transmission line, and these slag moving shafts are used as motors. An extremely compact tuner is disclosed in which the slag is moved by rotating the slag.

JP 2000-294550 A International Publication No. 2008/013112 Pamphlet International Publication No. 2011/040328 Pamphlet International Publication No. 2010/110256 Pamphlet

  By the way, when transmitting a microwave, if a higher order mode other than the TEM mode is generated, the propagation characteristics of the microwave are deteriorated. Therefore, the diameters of the outer conductor and the inner conductor are reduced so as not to be a higher order mode. Inevitably, an extremely thin slag moving shaft of about 4 mm is required. For this reason, it becomes difficult to ensure the length of (3/4) λ as the total movement range of the pair of slags. In particular, when the frequency of the microwave is set to 1 GHz or less, for example, 860 MHz in order to obtain a high-power microwave, the length of (3/4) λ becomes 261 mm, and the length is secured by a thin slag moving shaft. This becomes even more difficult.

  Therefore, although the total movement range of the pair of slags is set to λ / 2, in this case, a range that cannot be matched is generated.

  The present invention has been made in view of the above points, and provides a tuner capable of ensuring a necessary matching range even if the slag movement axis is thin, and a microwave plasma source having such a tuner. Is an issue.

  In order to solve the above-described problems, a first aspect of the present invention is that a microwave transmitted from a microwave power source is fed, and the microwave is transmitted to a planar antenna that radiates the microwave, and the impedance of the load is set to A tuner that matches the characteristic impedance of a wave power source, has a power feeding portion to which microwaves are fed, and constitutes a coaxial transmission line including a cylindrical first outer conductor and a cylindrical first inner conductor And a first slag movement for moving the first slag provided in the first inner conductor, the first slag moving between the first outer conductor and the first inner conductor. A coaxial transmission line having a first slag moving part having an axis, an output end for outputting microwaves to the planar antenna, and comprising a cylindrical second outer conductor and a cylindrical second inner conductor; And a second slag that moves between the second outer conductor and the second inner conductor, and that is provided inside the second inner conductor and moves the second slag. A second slag moving part having a slag moving shaft, and the movable range of the first slag of the first slag moving part and the movable range of the second slag of the second slag moving part are both Provided is a tuner characterized by having a length of 1/2 wavelength of a microwave.

  The tuner according to the first aspect further includes an intermediate coaxial transmission line provided between the first slag moving unit and the second slag moving unit, and the first slag moving unit and the intermediate coaxial transmission. The path and the second slag moving part can be integrated to form a microwave transmission path.

  The first slag moving unit, the intermediate coaxial transmission line, and the second slag moving unit may be arranged in a straight line.

  The first slag moving unit and the second slag moving unit may be provided perpendicular to the intermediate coaxial transmission line. In this case, the first slag moving unit and the second slag moving unit are connected perpendicularly to the intermediate coaxial transmission line and arranged so that the overall shape is π-shaped. can do.

  A second aspect of the present invention is a microwave plasma source used in a plasma processing apparatus for performing plasma processing by forming microwave plasma in a chamber, and has a microwave power source and outputs a microwave. A microwave output unit, and a microwave supply unit for transmitting the microwave output from the microwave output unit and radiating the microwave into the chamber, wherein the microwave supply unit is a tuner according to the first aspect. And a microwave plasma source, and a planar antenna that radiates the transmitted microwave toward the chamber. A microwave plasma source is provided.

  In the microwave plasma source according to the second aspect, the microwave output unit includes a distributor that distributes the microwaves into a plurality of portions, and the microwave supply unit transfers the distributed microwaves into the chamber. A plurality of antenna modules are provided, and each of the antenna modules may include the tuner and the antenna unit.

  According to the present invention, the first slag moving part and the second slag moving part both having a coaxial structure are provided, and the first slag is first driven by the first slag moving shaft in the first inner conductor. The second slag is moved in the slag moving part, and the second slag is moved by the second slag moving shaft in the second inner conductor, and the slag movable range of the first slag moving part and the second slag moving part is increased. Since λ / 2 is used, impedance matching can be performed in the entire range on the Smith chart even if the slug movement axis is thin.

It is sectional drawing which shows schematic structure of the plasma processing apparatus used for 1st Embodiment. It is a block diagram which shows the structure of the microwave plasma source in the plasma processing apparatus of FIG. It is sectional drawing which shows the structure of the tuner used for the microwave plasma source of FIG. FIG. 4 is a sectional view taken along line AA ′ in FIG. 3. It is BB 'sectional drawing of FIG. It is CC 'sectional drawing of FIG. It is sectional drawing which shows schematic structure of the tuner of the conventional structure which can perform the impedance matching in all the points on a Smith chart. It is sectional drawing which shows schematic structure of the tuner of the conventional structure from which the range which can perform impedance matching becomes a partial range of a Smith chart. It is a figure which shows the matching possible range on a Smith chart in the tuner of FIG. It is a Smith chart for demonstrating the movable range of the slag in the case of impedance adjustment in 1st Embodiment. It is sectional drawing which shows the tuner used for a microwave plasma source in 2nd Embodiment.

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

<First Embodiment>
(Plasma processing equipment)
FIG. 1 is a sectional view showing a schematic configuration of the plasma processing apparatus used in the first embodiment, and FIG. 2 is a configuration diagram showing a configuration of a microwave plasma source in the plasma processing apparatus of FIG.

  The plasma processing apparatus 100 is configured as a plasma etching apparatus that performs, for example, an etching process on a wafer, and is a substantially cylindrical grounded chamber made of a metal material such as aluminum or stainless steel that is hermetically configured. 1, a microwave plasma source 2 for forming microwave plasma in the chamber 1, and an overall control unit 3. An opening 1 a is formed in the upper part of the chamber 1, and the microwave plasma source 2 is provided so as to face the inside of the chamber 1 from the opening 1 a.

  In the chamber 1, a susceptor 11 for horizontally supporting a wafer W as an object to be processed is supported by a cylindrical support member 12 erected at the center of the bottom of the chamber 1 via an insulating member 12 a. Is provided. Examples of the material constituting the susceptor 11 and the support member 12 include aluminum whose surface is anodized (anodized).

  Although not shown, the susceptor 11 includes an electrostatic chuck for electrostatically attracting the wafer W, a temperature control mechanism, a gas flow path for supplying heat transfer gas to the back surface of the wafer W, and the wafer. In order to convey W, elevating pins and the like that elevate and lower are provided. Furthermore, a high frequency bias power supply 14 is electrically connected to the susceptor 11 via a matching unit 13. By supplying high frequency power from the high frequency bias power source 14 to the susceptor 11, ions in the plasma are attracted to the wafer W side.

  An exhaust pipe 15 is connected to the bottom of the chamber 1, and an exhaust device 16 including a vacuum pump is connected to the exhaust pipe 15. Then, by operating the exhaust device 16, the inside of the chamber 1 is exhausted, and the inside of the chamber 1 can be decompressed at a high speed to a predetermined degree of vacuum. Further, on the side wall of the chamber 1, a loading / unloading port 17 for loading / unloading the wafer W and a gate valve 18 for opening / closing the loading / unloading port 17 are provided.

  A shower plate 20 that discharges a processing gas for plasma etching toward the wafer W is horizontally provided above the susceptor 11 in the chamber 1. The shower plate 20 has a gas flow path 21 formed in a lattice shape and a large number of gas discharge holes 22 formed in the gas flow path 21. It is a space part 23. A pipe 24 extending outside the chamber 1 is connected to the gas flow path 21 of the shower plate 20, and a processing gas supply source 25 is connected to the pipe 24.

  On the other hand, a ring-shaped plasma gas introduction member 26 is provided along the chamber wall above the shower plate 20 of the chamber 1, and the plasma gas introduction member 26 has a number of gas discharge holes on the inner periphery. Is provided. A plasma gas supply source 27 for supplying plasma gas is connected to the plasma gas introduction member 26 via a pipe 28. Ar gas or the like is preferably used as the plasma generating gas.

  The plasma gas introduced into the chamber 1 from the plasma gas introduction member 26 is turned into plasma by the microwave introduced into the chamber 1 from the microwave plasma source 2, and this Ar plasma passes through the space 23 of the shower plate 20. Then, the processing gas discharged from the gas discharge holes 22 of the shower plate 20 is excited to form plasma of the processing gas. Note that the plasma generation gas and the processing gas may be supplied by the same supply member.

  A top plate 110 is provided on the upper portion of the chamber 1 through a support ring 29, and the microwave plasma source 2 is disposed on the top plate 110.

  The overall control unit 3 includes a controller (computer) including a microprocessor, and each component (microwave plasma source 2, high frequency power source 14, gate valve 18, gas supply sources 25, 27, etc.) in the plasma processing apparatus 100. ) To control. The control unit 3 includes a storage unit storing a process sequence of the plasma processing apparatus 100 and a process recipe that is a control parameter, an input unit, a display, and the like, and controls a process in the plasma processing apparatus 100 according to the selected process recipe. It is like that.

(Microwave plasma source)
Next, the microwave plasma source 2 will be described.
As shown in FIG. 2, the microwave plasma source 2 includes a microwave output unit 30 that distributes the microwaves to a plurality of paths and outputs microwaves, and transmits the microwaves output from the microwave output unit 30 to enter the chamber 1. And a microwave supply unit 40 for radiating.

  The microwave output unit 30 includes a microwave power source 31, a microwave oscillator 32, an amplifier 33 that amplifies the oscillated microwave, and a distributor 34 that distributes the amplified microwave into a plurality of parts. .

  The microwave oscillator 32 causes, for example, a PLL oscillation of a microwave having a predetermined frequency (for example, 860 MHz). The distributor 34 distributes the microwave amplified by the amplifier 33 while matching the impedance between the input side and the output side so that the loss of the microwave does not occur as much as possible. In addition, as a frequency of the microwave, a range from 700 MHz to 3 GHz can be used in addition to 860 MHz.

  The microwave supply unit 40 includes a plurality of antenna modules 41 that guide the microwaves distributed by the distributor 34 into the chamber 1. Each antenna module 41 includes an amplifier unit 42 that mainly amplifies the distributed microwave, a tuner 43 that performs impedance matching of the microwave amplified by the amplifier unit 42, and a planar slot antenna provided at the tip of the tuner 43. The antenna unit 44 has 101. The tuner 43 and the antenna unit 44 are provided integrally. A microwave is radiated from the antenna portion 44 in each antenna module 41 into the chamber 1.

  The amplifier unit 42 includes a phase shifter 46, a variable gain amplifier 47, a main amplifier 48 constituting a solid state amplifier, and an isolator 49.

  The phase shifter 46 is configured to change the phase of the microwave, and by adjusting this, the radiation characteristic can be modulated. For example, the plasma distribution can be changed by controlling the directivity by adjusting the phase for each antenna module. Further, circularly polarized waves can be obtained by shifting the phase by 90 ° between adjacent antenna modules. The phase shifter 46 can be used for the purpose of spatial synthesis in the tuner by adjusting the delay characteristics between components in the amplifier. However, the phase shifter 46 does not need to be provided when such modulation of the radiation characteristics and adjustment of the delay characteristics between the components in the amplifier are unnecessary.

  The variable gain amplifier 47 is an amplifier for adjusting the power level of the microwave input to the main amplifier 48, adjusting the variation of individual antenna modules, or adjusting the plasma intensity. By changing the variable gain amplifier 47 for each antenna module, the generated plasma can be distributed.

  The main amplifier 48 constituting the solid state amplifier can be configured to include, for example, an input matching circuit, a semiconductor amplifying element, an output matching circuit, and a high Q resonance circuit.

  The isolator 49 separates reflected microwaves reflected by the antenna unit 44 and directed to the main amplifier 48, and includes a circulator and a dummy load (coaxial terminator). The circulator guides the microwave reflected by the antenna unit 44 to the dummy load, and the dummy load converts the reflected microwave guided by the circulator into heat.

  Each component of the microwave plasma source 2 is controlled by the overall control unit 3.

(Tuner)
Next, the tuner 43 will be described.
FIG. 3 is a cross-sectional view showing the tuner 43.
The tuner 43 is fed with the microwave transmitted from the microwave power source 31 and transmits the microwave to the planar slot antenna 101 that radiates the microwave, and matches the impedance of the load with the characteristic impedance of the microwave power source 31. It is configured as a slag tuner that performs impedance matching with two slags. As shown in FIG. 3, the tuner 43 has a first slag moving part 51 and a second slag moving part 52, both of which have a coaxial structure, and an intermediate coaxial transmission line provided therebetween. 53. These are arranged in a straight line from the top in the order of the first slag moving part 51, the intermediate coaxial transmission line 53, and the second slag moving part 52, and constitute a microwave transmission line together.

  The first slag moving part 51 includes a cylindrical first outer conductor 61, a cylindrical first inner conductor 62 provided coaxially within the first outer conductor 61, and a first outer conductor 61, The power supply mechanism 64 includes a first slag 63 made of a dielectric material such as alumina that moves up and down in the space between the first inner conductor 62 and microwave power is supplied from the power supply mechanism 64.

  In the internal space of the first inner conductor 62 of the first slag moving part 51, a first slag moving shaft 65 for moving the first slag 63 is provided, for example, formed of a screw rod formed with a trapezoidal screw along its longitudinal direction. It has been. A first motor 67 is connected to the upper portion of the first slag moving shaft 65 via an appropriate transmission mechanism.

  As shown in FIG. 4 which is an AA ′ sectional view of FIG. 3, the first slag 63 has an annular shape, and a first sliding member 66 made of a resin having sliding property is fitted therein. The first sliding member 66 is screwed to the first slag moving shaft 65. The first inner conductor 62 is formed with three slits 62a at equal intervals along the longitudinal direction. The first sliding member 66 has three protrusions 66a at equal intervals so as to correspond to the slits 62a. The first sliding member 66 is fitted into the first slag 63 with the protrusions 66 a being in contact with the inner periphery of the first slag 63. The outer peripheral surface of the first sliding member 66 is in contact with the inner peripheral surface of the first inner conductor 62 without play, and the first sliding member 66 is moved in the first slag movement shaft 65 by rotating the first slag moving shaft 65. 1 The inner conductor 62 is slid up and down. That is, the inner peripheral surface of the first inner conductor 62 functions as a sliding guide for the first slug 63. Thus, the first slag 63 is moved up and down by rotating the first slag moving shaft 65 by the first motor 67. The movable range of the first slag 63 in the first slag moving unit 51 is λ / 2 where λ is the in-tube wavelength of the microwave. A bottom plate 68 is provided at the lower end of the first slag moving shaft 65. The first slag moving shaft 65 and the bottom plate 68 are separated by about 2 to 5 mm in order to absorb vibration during driving. The bottom plate 68 may function as a bearing portion for the first slag moving shaft 65.

  The second slag moving part 52 includes a cylindrical second outer conductor 71, a cylindrical second inner conductor 72 provided coaxially in the second outer conductor 71, and a second outer conductor 71. A second slug 73 made of a dielectric material such as alumina that moves up and down in a space between the second inner conductor 72 and a lower end thereof connected to the antenna unit 44.

  In the internal space of the second inner conductor 72 of the second slag moving part 52, there is provided a second slag moving shaft 75 for moving the second slag 73 made of, for example, a screw rod formed with a trapezoidal screw along its longitudinal direction. It has been. A second motor 77 is connected to the upper part of the second slag moving shaft 75 via an appropriate transmission mechanism.

  As shown in FIG. 5 which is a BB ′ sectional view of FIG. 3, the second slag 73 has an annular shape like the first slag 63, and a second sliding member 76 made of a resin having slipperiness is fitted inside the second slag 73. ing. The second sliding member 76 is screwed to the second slag moving shaft 75. Three slits 72a are formed in the second inner conductor 72 at equal intervals along the longitudinal direction. The second sliding member 76 has three protrusions 76a at equal intervals so as to correspond to the slits 72a. The second sliding member 76 is fitted into the second slag 73 in a state where the protrusions 76 a are in contact with the inner periphery of the second slag 73. The outer peripheral surface of the second sliding member 76 comes into contact with the inner peripheral surface of the second inner conductor 72 without play, and the second sliding member 76 is moved in the first direction by rotating the second slug moving shaft 75. 2 The inner conductor 72 is slid up and down. That is, the inner peripheral surface of the second inner conductor 72 functions as a sliding guide for the second slug 73. Accordingly, the second slag 73 is moved up and down by rotating the second slag moving shaft 75 by the second motor 77. The movable range of the second slag 73 in the second slag moving part 52 is λ / 2 where λ is the in-tube wavelength of the microwave. A bottom plate 78 is provided at the lower end of the second slag moving shaft 75. The second slag moving shaft 75 and the bottom plate 78 are separated from each other by about 2 to 5 mm in order to absorb vibration during driving. Note that the bottom plate 78 may function as a bearing portion of the second slag moving shaft 75.

  The power feeding mechanism 64 has a microwave power introduction port 81 for introducing microwave power provided on a side surface of the first outer conductor 61 of the first slag moving unit 51. A coaxial line 82 including an inner conductor 82a and an outer conductor 82b is connected to the microwave power introduction port 81 as a feed line for supplying the microwave amplified from the amplifier unit 42. A feeding antenna 90 that extends horizontally toward the inside of the first outer conductor 61 of the first slag moving part 51 is connected to the tip of the inner conductor 82 a of the coaxial line 82.

  The feed antenna 90 is formed, for example, by cutting a metal plate such as aluminum and then fitting it on a dielectric member such as Teflon (registered trademark). The upper end surface of the first slag moving part 51 is a reflector, and a portion between the reflector and the feeding antenna 90 is made of a dielectric material such as Teflon (registered trademark) for shortening the effective wavelength of the reflected wave. A slow wave material 69 is provided. In addition, when a microwave with a high frequency such as 2.45 GHz is used, the slow wave material 69 may not be provided. At this time, the distance from the feeding antenna 90 to the reflecting plate is optimized, and the electromagnetic wave radiated from the feeding antenna 90 is reflected by the reflecting plate, so that the maximum electromagnetic wave is transmitted into the tuner 43 having the coaxial structure.

  The feed antenna 90 is connected to the inner conductor 82a of the coaxial line 82 at the microwave power introduction port 81 as shown in FIG. 6 which is a CC ′ sectional view of FIG. An antenna body 91 having a second pole 93 that radiates the supplied electromagnetic wave, and a reflection that extends from both sides of the antenna body 91 along the outside of the first inner conductor 62 of the first slag moving portion 51 and forms a ring shape. And a standing wave is formed by the electromagnetic wave incident on the antenna body 91 and the electromagnetic wave reflected by the reflecting part 94. The second pole 93 of the antenna body 91 is in contact with the first inner conductor 62.

  When the feeding antenna 90 radiates microwaves (electromagnetic waves), microwave power is fed to the space between the first outer conductor 61 and the first inner conductor 62 of the first slag moving part 51. Then, the microwave power supplied from the power feeding mechanism 64 is transmitted from the space between the first outer conductor 61 and the first inner conductor 62 of the first slag moving unit 51 to the outer conductor and the inner conductor of the intermediate coaxial transmission line 53. And the space between the second outer conductor 71 and the second inner conductor 72 of the second slag moving part 52 are propagated toward the antenna part 44.

  The positions of the first slag 63 and the second slag 73 are controlled by the slag controller 70. Specifically, based on the impedance value of the input end detected by an impedance detector (not shown) and the positional information of the first slag 63 and the second slag 73 detected by an appropriate sensor (not shown), the slag The controller 70 sends control signals to the first motor 67 and the second motor 77 to control the positions of the first slug 63 and the second slug 73, thereby adjusting the impedance. The slag controller 70 performs impedance matching so that the termination is 50Ω. When only one of the two slugs is moved, a trajectory passing through the origin of the Smith chart is drawn, and when both are moved simultaneously, only the phase rotates.

(Antenna part)
The antenna unit 44 is described together with the tuner in FIG. The antenna unit 44 functions as a microwave radiating antenna, is a planar slot antenna 101 having a planar shape and having a slot 101a, a slow wave member 102 provided on the upper surface of the planar slot antenna 101, and a front end side of the planar slot antenna 101. And a microwave transmission plate 103 made of a dielectric material.

  The shape of the slot 101a is set as appropriate so that microwaves can be radiated efficiently. A dielectric may be inserted into the slot 101a.

  A cylindrical member 102 a made of a conductor passes through the center of the slow wave member 102 to connect the bottom plate 78 of the second slag moving part 52 in the tuner 43 and the planar slot antenna 101. Therefore, the second inner conductor 72 of the second slag moving part 52 in the tuner 43 is connected to the planar slot antenna 101 via the bottom plate 78 and the cylindrical member 102a.

  The slow wave material 102 and the microwave transmission plate 103 are made of a dielectric having a dielectric constant larger than that of a vacuum, for example, a fluorine resin such as quartz, ceramics, polytetrafluoroethylene, or a polyimide resin. Since the microwave wavelength becomes longer in vacuum, the wavelength of the microwave is shortened by configuring the slow wave material 102 and the microwave transmitting plate 103 with a dielectric having a dielectric constant larger than that of the vacuum. The antenna can be made smaller. The slow wave material 102 can adjust the phase of the microwave according to its thickness, and the thickness thereof is adjusted so that the junction between the microwave transmitting plate 103 and the planar slot antenna 101 becomes a “wave” of standing waves. adjust. Thereby, reflection can be minimized and the radiation energy of the planar slot antenna 101 can be maximized.

  The second outer conductor 71 of the second slag moving part 52 extends to the periphery of the slow wave material 102 and covers the outside of the slow wave material 102. Further, the periphery of the planar slot antenna 101 is covered with a covered conductor 104.

  The microwave transmitting plate 103 is provided so as to be in contact with the planar slot antenna 101 and is fitted into the top plate 110. Then, the microwave amplified by the main amplifier 48 passes through the coaxial line 82 and is fed to the tuner 43 by the feeding mechanism 64, and the first slag moving unit 51 and the intermediate coaxial transmission line 53 constituting the microwave transmission path of the tuner 43. The second slag moving part 52 is transmitted in the TEM mode, reaches the planar slot antenna 101, radiates from the slot 101a, passes through the microwave transmitting plate 103, reaches the space in the chamber 1, and forms surface wave plasma. The

  In the present embodiment, the main amplifier 48, the tuner 43, and the planar slot antenna 101 are arranged close to each other. The tuner 43 and the planar slot antenna 101 constitute a lumped constant circuit existing within a half wavelength, and the planar slot antenna 101, the slow wave plate 102, and the microwave transmission plate 103 have a combined resistance of 50Ω. Since it is set, the tuner 43 is directly tuned with respect to the plasma load, and can efficiently transmit energy to the plasma.

(Operation of plasma processing equipment)
Next, the operation in the plasma processing apparatus 100 configured as described above will be described.
First, the wafer W is loaded into the chamber 1 and placed on the susceptor 11. Then, while introducing a plasma generation gas, for example, Ar gas, from the plasma generation gas supply source 27 through the pipe 28 and the plasma generation gas introduction member 26 into the chamber 1, microwaves from the microwave plasma source 2 are introduced into the chamber 1. Radiates to generate surface wave plasma.

Then, a processing gas, for example, an etching gas such as Cl ₂ gas is discharged from the processing gas supply source 25 into the chamber 1 through the pipe 24 and the shower plate 20. The discharged processing gas is excited by plasma that has passed through the space 23 of the shower plate 20 to be converted into plasma, and plasma processing, for example, etching processing is performed on the wafer W by the plasma of the processing gas.

  When generating the surface wave plasma, in the microwave plasma source 2, the microwave power oscillated from the microwave oscillator 32 of the microwave output unit 30 is amplified by the amplifier 33 and then distributed to a plurality by the distributor 34. The distributed microwave power is guided to the microwave supply unit 40. In the microwave supply unit 40, the microwave power distributed in plural is individually amplified by the main amplifier 48 constituting the solid-state amplifier, and is supplied to each tuner 43, so that the microwave passes through the tuner 43. Is transmitted. Specifically, power is supplied from the coaxial line 82 to the first slag moving unit 51 via the power supply mechanism 64, and the microwave is transmitted downward from the first slag moving unit 51 to the intermediate coaxial transmission line 53 and the second slag moving unit 52. Is transmitted to. At that time, the impedance is automatically matched by the first slag 63 and the second slag 73 of the tuner 43 and the planar slot antenna 101 passes from the tuner 43 through the slow wave member 102 of the antenna unit 44 in a state where there is substantially no power reflection. Are transmitted through the microwave transmission plate 103 and transmitted through the surface (lower surface) of the microwave transmission plate 103 in contact with the plasma to form a surface wave. Then, the electric power in each antenna unit 44 is spatially synthesized in the chamber 1, whereby surface wave plasma is generated in the space in the chamber 1, and the wafer W as the object to be processed is subjected to plasma processing.

  In this way, the microwaves distributed to a plurality of parts are individually amplified by the main amplifier 48 constituting the solid state amplifier, and individually introduced into the chamber 1 from the plurality of antenna units 44 to form surface waves. Since the space is synthesized in space, a large isolator or synthesizer is not required. In addition, the tuner 43 and the antenna unit 44 are provided as a single unit, so that the unit is compact. Further, the main amplifier 48, the tuner 43, and the planar slot antenna 101 are provided close to each other, and the tuner 43 and the planar slot antenna 101 constitute a lumped constant circuit and function as a resonator, so that impedance mismatch exists. Thus, the tuner 43 can be tuned with high accuracy including the plasma at the portion where the planar slot antenna is attached, and the influence of reflection can be reliably eliminated.

  Further, the tuner 43 and the planar slot antenna 101 are close to each other, constitute a lumped constant circuit, and function as a resonator, thereby eliminating the impedance mismatch up to the planar slot antenna 101 with high accuracy. In addition, since the mismatched portion can be substantially used as a plasma space, the tuner 43 can perform high-precision plasma control.

  By the way, as shown in FIG. 7, the conventional tuner 200 has a configuration in which two slugs 204 and 205 move between the outer conductor 202 and the inner conductor 203 of a single coaxial transmission line 201. When the in-tube wavelength is λ, the phase of the reflection coefficient at a certain point on the Smith chart can be changed by 360 ° by simultaneously moving the slugs 204 and 205 within the range of λ / 2. By moving only one slag within the range of λ / 4 with respect to the other slag, a point on the Smith chart can be moved to the origin, and by combining these, the total movement of the slags 204 and 205 is possible. By setting the range to (3/4) λ, impedance matching can be performed at all points on the Smith chart.

  When transmitting a microwave, if a higher order mode other than the TEM mode is generated, the propagation characteristics of the microwave are deteriorated. Therefore, the diameters of the outer conductor 202 and the inner conductor 203 are reduced so as not to be a higher order mode. In the case where the slag moving shaft is accommodated in the inner conductor 203, an extremely thin slag moving shaft of about 4 mm is inevitably required. For this reason, it becomes difficult to ensure the length of (3/4) λ as the total movement range of the pair of slags. In order to avoid this, if the total movable range of the slugs 204 and 205 is λ / 2 as shown in FIG. 8, the range where impedance matching can be performed is a partial range of the Smith chart as shown in FIG. Thus, a range that cannot be matched is generated.

  Therefore, in the present embodiment, the tuner 43 includes a first slag moving part 51, a second slag moving part 52, and an intermediate coaxial transmission line 53 between them, all of which have a coaxial structure. The microwave transmission path is integrally formed, and the first slag 63 is moved in the first slag moving part 51 by the first slag moving shaft 65 in the first inner conductor 62, and the second slag 73 is The second slag moving part 52 is moved by the second slag moving shaft 75 in the second inner conductor 72, and the slag movable range of the first slag moving part 51 and the second slag moving part 52 is set to λ / 2. As a result, even if the slug movement axis is thin, impedance matching can be performed in the entire range on the Smith chart.

  That is, as shown in FIG. 10, for example, by moving the first slag 63 and the second slag 73 simultaneously within the range of λ / 2, the phase of the reflection coefficient at point A on the Smith chart is indicated by a circle indicated by a broken line. As shown in B, it is possible to change 360 °, and by moving only one slag within the range of λ / 2 with respect to the other, a circle C passing through the origin and the point A can be drawn. By these combinations, impedance matching can be performed at all points on the Smith chart. Moreover, since the slag movable range of the 1st slag movement part 51 and the 2nd slag movement part 52 may be (lambda) / 2, even if a slag movement axis is thin, a problem will not arise.

  Further, by moving the two slugs in different coaxial transmission lines in this way, the entire tuner can be made thinner. As a result, a material having a higher dielectric constant can be used for the slag, and the slag can be made thinner.

<Second Embodiment>
In the second embodiment, only the tuner structure is different from that of the first embodiment. Therefore, only the configuration of the tuner will be described, and the rest is the same as in the first embodiment, and the description thereof will be omitted.

(Tuner)
FIG. 11 is a cross-sectional view showing a tuner used for the microwave plasma source in the second embodiment.
The tuner 43 ′ in this embodiment is configured as a slag tuner that performs impedance matching with two slags, and includes a first slag moving unit 51 and a second slag moving unit 52 having the same structure as in the first embodiment. And an intermediate coaxial transmission line 53 ′ provided between them. The first slag moving part 51 and the second slag moving part 52 are connected to the side surface of the intermediate coaxial transmission line 53 ′ perpendicularly to the intermediate coaxial transmission line 53 ′. More specifically, the intermediate coaxial transmission line 53 ′ is arranged so that its axial direction is horizontal, and the first slag moving part 51 and the second slag moving part 52 are connected to the intermediate coaxial transmission line 53 ′. It is connected to the lower part of the side surface so as to extend downward, and the whole forms a π shape. And the 1st slag movement part 51, intermediate | middle coaxial transmission line 53 ', and the 2nd slag movement part 52 comprise the microwave transmission path integrally. The first slag moving unit 51 has the same structure as that of the first embodiment, but the arrangement is different, and the power feeding mechanism 64 is arranged below.

  In addition, since the structure of the 1st slag moving part 51, the 2nd slag moving part 52, and the antenna part 44 is the same as 1st Embodiment, description is abbreviate | omitted.

  In such a tuner 43 ′, the microwaves fed from the power feeding mechanism 64 below the first slag moving part 51 are transmitted upward through the first slag moving part 51 and reach the intermediate coaxial transmission line 53 ′. In the intermediate coaxial transmission line 53 ′, the signal is transmitted horizontally and reaches the second slag moving unit 52, and is transmitted downward through the second slag moving unit 52. At this time, as in the first embodiment, the impedance is automatically matched by the first slag 63 and the second slag 73 of the tuner 43, and the delayed wave from the tuner 43 to the antenna unit 44 is substantially absent in the state of power reflection. It is radiated from the slot 101a of the planar slot antenna 101 through the material 102, further passes through the microwave transmission plate 103, and is transmitted through the surface (lower surface) of the microwave transmission plate 103 in contact with the plasma to form a surface wave. Then, the electric power in each antenna unit 44 is spatially synthesized in the chamber 1, whereby surface wave plasma is generated in the space in the chamber 1, and the wafer W as the object to be processed is subjected to plasma processing.

  At this time, as in the first embodiment, the first slag 63 moves in the first slag moving portion 51 by the first slag moving shaft 65 in the first inner conductor 62, and the second slag 73 moves in the second inner conductor. 72, the second slag moving part 52 is moved by the second slag moving shaft 75, and the slag movable range of the first slag moving part 51 and the second slag moving part 52 is set to λ / 2. Even if is narrow, impedance matching can be performed in the entire range on the Smith chart. Moreover, since the slag movable range of the 1st slag movement part 51 and the 2nd slag movement part 52 may be (lambda) / 2, even if a slag movement axis is thin, a problem will not arise.

  In addition, the slag 43 ′ having such a structure can provide all the other effects of the slag 43, and has a merit that the height can be made lower than the slag 43, and there is no allowance in the height direction. Etc. are advantageous.

<Other applications>
The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the idea of the present invention.

  For example, the connection form of the first slag moving unit, the intermediate coaxial transmission line, and the second slag moving shaft is not limited to the above two embodiments, and the first slag moving unit and the second slag moving unit. If the slug movement shaft can be provided independently, the intermediate coaxial transmission line is not necessarily provided.

  Further, the circuit configuration of the microwave output unit 30, the circuit configuration of the microwave supply unit 40, the main amplifier 48, and the like are not limited to the above embodiment. Specifically, when it is not necessary to control the directivity of the microwave radiated from the planar slot antenna or to make it circularly polarized, the phase shifter is unnecessary.

  In addition, the microwave supply unit 40 does not necessarily need to be configured by a plurality of antenna modules, and there may be one antenna module. Furthermore, although the shape of the slot of the planar slot antenna is not clearly drawn in the above embodiment, various slot patterns can be adopted depending on conditions.

  Furthermore, in the above embodiment, the etching processing apparatus is exemplified as the plasma processing apparatus to which the microwave plasma source is applied. However, the plasma processing apparatus is not limited to this, and other plasma processing such as film formation processing, oxynitride film processing, and ashing processing is performed. Can also be used.

DESCRIPTION OF SYMBOLS 1; Chamber 2; Microwave plasma source 11; Susceptor 12; Support member 16; Exhaust device 20; Shower plate 30; Microwave output part 40; Microwave supply part 41; Antenna module 42; Amplifier part 43, 43 ';44; Antenna portion 51; First slag moving portion 52; Second slag moving portion 53, 53 ′; Intermediate coaxial transmission line 61, 71; Outer conductor 62, 72; Inner conductor 63, 73; Slag 64; Feed mechanism 65, 75; slag moving shaft 67, 77; motor 70; slag controller 100; plasma processing apparatus 101; planar slot antenna 110; top plate W;

Claims (7)

A microwave is fed from a microwave power source, transmits the microwave to a planar antenna that radiates the microwave, and matches the impedance of the load to the characteristic impedance of the microwave power source,
The first outer conductor and the first inner conductor have a power feeding portion to which microwaves are fed, and form a coaxial transmission line including a cylindrical first outer conductor and a cylindrical first inner conductor. And a first slag moving part having a first slag moving shaft for moving the first slag provided in the first inner conductor,
An output end for outputting microwaves to the planar antenna has a coaxial transmission line composed of a cylindrical second outer conductor and a cylindrical second inner conductor, and the second outer conductor and the first A second slag moving part having a second slag moving between the two inner conductors and having a second slag moving shaft for moving the second slag provided in the second inner conductor;
Comprising
The movable range of the first slag of the first slag moving unit and the movable range of the second slag of the second slag moving unit are both 1/2 wavelength in length of the microwave. Tuner to do.   And further comprising an intermediate coaxial transmission line provided between the first slag moving part and the second slag moving part, the first slag moving part, the intermediate coaxial transmission line, and the second slag moving part. The tuner according to claim 1, wherein a microwave transmission path is integrally formed.   3. The tuner according to claim 2, wherein the first slag moving unit, the intermediate coaxial transmission line, and the second slag moving unit are linearly arranged.   4. The tuner according to claim 3, wherein the first slag moving unit and the second slag moving unit are provided perpendicular to the intermediate coaxial transmission line. 5.   The first slag moving unit and the second slag moving unit are connected perpendicularly to the intermediate coaxial transmission line, and are arranged so that the overall shape is π-shaped. Item 5. The tuner according to item 4. A microwave plasma source used in a plasma processing apparatus for performing plasma processing by forming microwave plasma in a chamber,
A microwave output unit having a microwave power source and outputting a microwave;
A microwave supply unit for transmitting the microwave output from the microwave output unit and radiating the microwave into the chamber;
The microwave supply unit is
A tuner according to any one of claims 1 to 5, and an antenna unit having a planar antenna that transmits a microwave from the tuner and radiates the transmitted microwave toward the chamber. Microwave plasma source.   The microwave output unit has a distributor that distributes the microwaves into a plurality, and the microwave supply unit has a plurality of antenna modules that guide the distributed microwaves into the chamber, The microwave plasma source according to claim 6, wherein each antenna module includes the tuner and the antenna unit.

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