JP2012089334A - Microwave plasma source and plasma processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microwave plasma source and a plasma processing apparatus using the same capable of suppressing influence by a standing wave of a microwave in a processing container as much as possible and increasing plasma density uniformity in a chamber.SOLUTION: A microwave plasma source 2 comprises a microwave supply part 40. The microwave supply part 40 comprises: a plurality of microwave introduction mechanisms 43 which introduce the microwave into the processing container; and a plurality of phase shifters 46 which adjust the phases of microwaves input to each of the plurality of microwave introduction mechanisms 43. For the plurality of microwave introduction mechanisms 43 adjacent to each other, the microwave plasma source 2 adjusts the phases of the microwaves input to a plurality of adjacent microwave introduction mechanisms 43 with the plurality of phase shifters 46 so that the input phase of one microwave is fixed and the input phase of the other microwave is changed by a periodic waveform.

Description

  The present invention relates to a microwave plasma source and a plasma processing apparatus using the same.

  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 (Radial Line Slot Antenna) microwave plasma processing apparatus capable of uniformly forming a high-density, low electron temperature surface wave plasma has been attracting attention (for example, a patent). Reference 1).

  The RLSA microwave plasma processing apparatus is provided with a planar antenna (Radial Line Slot Antenna) in which slots are formed in a predetermined pattern at the upper part of a chamber (processing vessel), and is guided from a microwave source through a coaxial waveguide. The microwave is radiated into the chamber from the slot of the planar antenna, the gas introduced into the chamber is converted into plasma by the microwave electric field, and the object to be processed such as a semiconductor wafer is subjected to plasma processing.

  In such an RLSA microwave plasma apparatus, when adjusting the plasma distribution, it is necessary to prepare a plurality of antennas having different slot shapes, patterns, etc., and to exchange the antennas, which is extremely complicated.

  On the other hand, Patent Document 2 discloses a microwave plasma source that divides microwaves into a plurality of components, radiates the microwaves into the chamber through a plurality of antenna modules, and synthesizes the microwaves in the chamber space. ing.

  Thus, by spatially synthesizing microwaves using a plurality of antenna modules, the plasma distribution can be adjusted by adjusting the phase and intensity of the microwaves radiated from the antennas of the respective antenna modules.

JP 2000-294550 A International Publication No. 2008/013112 Pamphlet

  However, when plasma is formed by radiating microwaves into the chamber using a plurality of antenna modules in this way, the antinodes and nodes of standing waves generated when microwaves are radiated into the chamber are generated. There is a problem that it becomes apparent, which causes localization of the electron density distribution in the plasma and deteriorates the uniformity of the plasma density distribution.

  The present invention has been made in view of such circumstances, and it is possible to suppress as much as possible the fixing of the positions of the antinodes and nodes of the microwave standing wave in the processing container, and to reduce the plasma density in the chamber. It is an object of the present invention to provide a microwave plasma source capable of increasing uniformity and a plasma processing apparatus using the same.

  According to a first aspect of the present invention, there is provided a plasma source for generating microwaves by introducing a microwave into a processing vessel for performing plasma processing and converting the gas supplied into the processing vessel into plasma. A generation mechanism; and a microwave supply unit that supplies the generated microwave into the processing container, wherein the microwave supply unit includes a plurality of microwave introduction mechanisms that introduce microwaves into the processing container; A plurality of phase shifters for adjusting the phase of the microwaves input to each of the plurality of microwave introduction mechanisms, and one of the plurality of microwave introduction mechanisms adjacent to the input phase of one of the microwaves Is fixed and the other microwave input phase is changed by a periodic waveform, or the microwave input phases of both adjacent microwave introduction mechanisms are mutually overlapped. As varied by et no periodic waveform to provide a microwave plasma source and adjusts the phases of microwaves inputted to the plurality of microwave introduction mechanism by said plurality of phase shifters.

  In the first aspect, any one of a sine wave, a triangular wave, a trapezoidal wave, and a sine wave waveform can be used as the periodic waveform.

  In addition, a top plate that constitutes an upper wall of the processing container and transmits microwaves radiated from the plurality of microwave introduction mechanisms is provided with a plurality of dielectrics provided at positions corresponding to the plurality of microwave introduction mechanisms. The structure may include a body member and a metal frame that supports the dielectric member, and the frame may have a honeycomb structure. In this case, the frame has a gas flow path and a plurality of gas discharge holes, and a gas necessary for plasma processing can be discharged from the gas discharge holes toward the processing container. .

In a second aspect of the present invention, a processing container that accommodates a substrate to be processed, a mounting table on which the substrate to be processed is placed in the processing container, a gas supply mechanism that supplies gas into the processing container, The microwave plasma source according to the first aspect is provided, plasma is generated by the microwave introduced from the microwave plasma source into the processing container, and the substrate is processed by the plasma. A plasma processing apparatus is provided.

  According to the present invention, for the adjacent ones of the plurality of microwave introduction mechanisms, the input phase of one microwave is fixed and the input phase of the other microwave is changed by a periodic waveform, or adjacent The phase of the microwaves input to the plurality of microwave introduction mechanisms by the plurality of phase shifters is changed so that the input phases of both microwaves of the microwave introduction mechanism are changed by a periodic waveform that does not overlap each other. Since the adjustment is performed, the positions of the nodes and the antinodes of the standing wave in the microwave radiated into the processing container are continuously changed to average the electric field strength, thereby improving the in-plane uniformity of the electric field strength. Therefore, uniform plasma processing can be performed with uniform electron density in the processing vessel, that is, plasma density.

It is sectional drawing which shows schematic structure of the surface wave plasma processing apparatus which has a microwave plasma source which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the structure of a microwave plasma source. It is a top view which shows typically the microwave supply part in a microwave plasma source. It is a figure which shows the example of a circuit structure of the main amplifier used for the antenna module in a microwave plasma source. It is sectional drawing which shows the microwave introduction mechanism used for the antenna module in a microwave plasma source. It is a cross-sectional view by the AA 'line of FIG. 5 which shows the electric power feeding mechanism of a microwave introduction mechanism. It is a cross-sectional view by the BB 'line of FIG. 5 which shows the slag and sliding member in a tuner. It is a schematic diagram for demonstrating what changed the input phase of the microwave with the periodic waveform among the seven microwave introduction mechanisms mounted in the microwave plasma source. It is a figure which shows the time change of an input phase when one phase of an adjacent microwave introduction mechanism is fixed at 0 degree, and the other input phase is made into a sine wave. It is a figure which shows an example other than the sine wave of a periodic waveform. Using a plasma source with seven microwave introduction mechanisms as shown in FIG. 3, the microwave input phase of all microwave introduction mechanisms is 0 °, and the input of the three microwave introduction mechanisms on the outer periphery. It is a chart which shows the result of grasping | ascertaining the electric field distribution in a chamber when changing a phase to 180 degrees. It is a top view which shows typically the microwave supply part and top plate of a plasma source in the 2nd Embodiment of this invention. It is sectional drawing by CC 'line of FIG. It is a top view which shows typically the modification of the structure of a top plate. It is a bottom view which shows the other modification of the structure of a top plate.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
<First Embodiment>
FIG. 1 is a sectional view showing a schematic configuration of a surface wave plasma processing apparatus having a microwave plasma source according to a first embodiment of the present invention, and FIG. 2 is a configuration diagram showing the configuration of the microwave plasma source. 3 is a plan view schematically showing a microwave supply unit in the microwave plasma source, FIG. 4 is a diagram showing an example of a circuit configuration of a main amplifier used in an antenna module in the microwave plasma source, and FIG. FIG. 6 is a cross-sectional view of the microwave introduction mechanism used in the antenna module in the plasma source, FIG. 6 is a cross-sectional view taken along line AA ′ of FIG. 5 showing the power supply mechanism of the microwave introduction mechanism, and FIG. It is a cross-sectional view by the BB 'line of FIG. 5 shown.

  The surface wave plasma processing apparatus 100 is configured as a plasma etching apparatus that performs, for example, an etching process as a plasma process on a wafer, and is grounded in a substantially cylindrical shape made of an airtight metal material such as aluminum or stainless steel. A chamber 1 and a microwave plasma source 2 for forming microwave plasma in the chamber 1. 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. Elevating pins and the like that move up and down to convey W are provided as necessary. 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. As the plasma gas, a rare gas such as Ar gas is preferably used.

  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 plasma passes through the space 23 of the shower plate 20. The processing gas discharged from the gas discharge hole 22 of the shower plate 20 is excited to form plasma of the processing gas.

  The microwave plasma source 2 is provided on a top plate 110 supported by a support ring 29 provided at the top of the chamber 1. A space between the support ring 29 and the top plate 110 is hermetically sealed. As shown in FIG. 2, the microwave plasma source 2 includes a microwave output unit 30 that outputs the microwaves distributed to a plurality of paths, and a microwave output from the microwave output unit 30 is guided to the chamber 1. 1 and a microwave supply unit 40 for radiating into the inside.

  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, 2.45 GHz). 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. Note that as the frequency of the microwave, in addition to 2.45 GHz, 8.35 GHz, 5.8 GHz, 1.98 GHz, 915 MHz, or the like can be used.

  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 and a microwave introduction mechanism 43. The microwave introduction mechanism 43 includes a tuner 60 for matching impedance and an antenna unit 45 that radiates the amplified microwave into the chamber 1. A microwave is radiated into the chamber 1 from the antenna portion 45 of the microwave introduction mechanism 43 in each antenna module 41. As shown in FIG. 3, the microwave supply unit 40 has seven antenna modules 41, and six microwave introduction mechanisms 43 of each antenna module 41 have a circumferential shape and one at the center thereof. It arrange | positions on the top plate 110 which makes | forms a circle. The top plate 110 functions as a vacuum seal and a microwave transmission plate, and includes a metal frame 110a, and a dielectric member 110b made of a dielectric material such as quartz fitted in a portion where the microwave introduction mechanism 43 is disposed. have.

  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. In this embodiment, as will be described later, the standing wave of the microwave is suppressed by fixing the phase of a predetermined antenna module and continuously changing the phase of the antenna module adjacent thereto.

  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 has, for example, an input matching circuit 131, a semiconductor amplifying element 132, an output matching circuit 133, and a high Q resonance circuit 134 as shown in FIG. Can do.

  The isolator 49 separates the reflected microwaves reflected by the antenna unit 45 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 45 to the dummy load, and the dummy load converts the reflected microwave guided by the circulator into heat.

Next, the microwave introduction mechanism 43 will be described.
As shown in FIGS. 5 and 6, the microwave introduction mechanism 43 includes a coaxial waveguide 44 that transmits microwaves and an antenna unit 45 that radiates the microwaves transmitted through the waveguide 44 into the chamber 1. Have. The microwaves radiated from the microwave introduction mechanism 43 into the chamber 1 are combined in the space in the chamber 1, and surface wave plasma is formed in the chamber 1.

  The waveguide 44 is formed by coaxially arranging a cylindrical outer conductor 52 and a rod-shaped inner conductor 53 provided at the center thereof, and an antenna portion 45 is provided at the tip of the waveguide 44. In the waveguide 44, the inner conductor 53 is a power supply side, and the outer conductor 52 is a ground side. The upper end of the outer conductor 52 and the inner conductor 53 is a reflection plate 58.

  A power feeding mechanism 54 that feeds microwaves (electromagnetic waves) is provided on the proximal end side of the waveguide 44. The power feeding mechanism 54 has a microwave power introduction port 55 for introducing microwave power provided on a side surface of the waveguide 44 (outer conductor 52). A coaxial line 56 including an inner conductor 56 a and an outer conductor 56 b is connected to the microwave power introduction port 55 as a feed line for supplying the microwave amplified from the amplifier unit 42. A feeding antenna 90 extending horizontally toward the inside of the outer conductor 52 is connected to the tip of the inner conductor 56 a of the coaxial line 56.

  The feed antenna 90 is formed, for example, as a microstrip line on a PCB substrate that is a printed circuit board. A slow wave material 59 made of a dielectric material such as Teflon (registered trademark) for shortening the effective wavelength of the reflected wave is provided between the reflector 58 and the feeding antenna 90. In the case of using a microwave with a high frequency such as 2.45G, the slow wave material 59 may not be provided. At this time, the electromagnetic wave radiated from the power feeding antenna 90 is reflected by the reflection plate 58, so that the maximum electromagnetic wave is transmitted into the waveguide 44 having the coaxial structure. In that case, the distance from the feeding antenna 90 to the reflector 58 is set to a half wavelength multiple of about λg / 4.

  As shown in FIG. 6, the feed antenna 90 is connected to the inner conductor 56a of the coaxial line 56 at the microwave power introduction port 55, and the first pole 92 to which the electromagnetic wave is supplied and the second electromagnetic wave to radiate the supplied electromagnetic wave. The antenna main body 91 having the pole 93 and the reflection part 94 extending from both sides of the antenna main body 91 along the outside of the inner conductor 53 to form a ring shape, and the electromagnetic wave incident on the antenna main body 91 and the reflection part A standing wave is formed by the electromagnetic wave reflected at 94. The second pole 93 of the antenna body 91 is in contact with the inner conductor 53.

  When the feeding antenna 90 radiates microwaves (electromagnetic waves), microwave power is fed to the space between the outer conductor 52 and the inner conductor 53. Then, the microwave power supplied to the power feeding mechanism 54 propagates toward the antenna unit 45.

  The waveguide 44 is provided with a tuner 60. The tuner 60 matches the impedance of the load (plasma) in the chamber 1 with the characteristic impedance of the microwave power source in the microwave output unit 30, and moves up and down between the outer conductor 52 and the inner conductor 53 2. Two slags 61a and 61b, and a slag driving unit 70 provided on the outer side (upper side) of the reflection plate 58.

  Among these slags, the slag 61a is provided on the slag drive unit 70 side, and the slag 61b is provided on the antenna unit 45 side. Further, in the inner space of the inner conductor 53, two slag moving shafts 64a and 64b for slag movement are provided along a longitudinal direction of the inner conductor 53.

  As shown in FIG. 7, the slag 61a has an annular shape made of a dielectric, and a sliding member 63 made of a resin having slipperiness is fitted inside the slag 61a. The sliding member 63 is provided with a screw hole 65a into which the slag moving shaft 64a is screwed and a through hole 65b into which the slag moving shaft 64b is inserted. On the other hand, the slag 61b has a screw hole 65a and a through hole 65b as in the case of the slag 61a. On the contrary to the slag 61a, the screw hole 65a is screwed to the slag moving shaft 64b and is connected to the through hole 65b. The slag moving shaft 64a is inserted. Thereby, the slag 61a moves up and down by rotating the slag movement shaft 64a, and the slag 61b moves up and down by rotating the slag movement shaft 64b. That is, the slugs 61a and 61b are moved up and down by a screw mechanism including the slug moving shafts 64a and 64b and the sliding member 63.

  Three slits 53a are formed in the inner conductor 53 at equal intervals along the longitudinal direction. On the other hand, the sliding member 63 is provided with three protrusions 63a at equal intervals so as to correspond to the slits 53a. Then, the sliding member 63 is fitted into the slags 61a and 61b in a state where the protruding portions 63a are in contact with the inner circumferences of the slags 61a and 61b. The outer peripheral surface of the sliding member 63 comes into contact with the inner peripheral surface of the inner conductor 53 without play, and the sliding member 63 slides up and down the inner conductor 53 by rotating the slug movement shafts 64a and 64b. It is supposed to be. That is, the inner peripheral surface of the inner conductor 53 functions as a sliding guide for the slugs 61a and 61b. The width of the slit 53a is preferably 5 mm or less. Thereby, as will be described later, the microwave power leaking into the inner conductor 53 can be substantially eliminated, and the radiation efficiency of the microwave power can be kept high.

As the resin material constituting the sliding member 63, a resin having good sliding property and relatively easy processing, for example, polyphenylene sulfide (PPS) resin (trade name: BEAREE AS5000 (manufactured by NTN Corporation)) is suitable. Can be cited as a thing.

  The slag moving shafts 64 a and 64 b extend through the reflecting plate 58 to the slag driving unit 70. A bearing (not shown) is provided between the slug moving shafts 64a and 64b and the reflection plate 58. Further, a bearing portion 67 made of a conductor is provided at the lower end of the inner conductor 53, and the lower ends of the slag movement shafts 64 a and 64 b are pivotally supported by the bearing portion 67.

  The slag drive unit 70 has a casing 71, slag movement shafts 64a and 64b extend into the casing 71, and gears 72a and 72b are attached to the upper ends of the slag movement shafts 64a and 64b, respectively. The slag drive unit 70 is provided with a motor 73a that rotates the slag movement shaft 64a and a motor 73b that rotates the slag movement shaft 64b. A gear 74a is attached to the shaft of the motor 73a, and a gear 74b is attached to the shaft of the motor 73b. The gear 74a meshes with the gear 72a, and the gear 74b meshes with the gear 72b. Accordingly, the slag movement shaft 64a is rotated by the motor 73a via the gears 74a and 72a, and the slag movement shaft 64b is rotated by the motor 73b via the gears 74b and 72b. The motors 73a and 73b are, for example, stepping motors.

  The slag moving shaft 64b is longer than the slag moving shaft 64a and reaches the upper side. Therefore, the positions of the gears 72a and 72b are vertically offset, and the motors 73a and 73b are also vertically offset. Thereby, the space of a power transmission mechanism such as a motor and gears can be reduced, and the casing 71 that accommodates them can have the same diameter as the outer conductor 52.

  Incremental encoders 75a and 75b for detecting the positions of the slugs 61a and 61b are provided on the motors 73a and 73b so as to be directly connected to these output shafts.

  The positions of the slags 61a and 61b are controlled by the slag controller 68. Specifically, the slag controller 68 controls the motors 73a and 73b based on the impedance value of the input end detected by an impedance detector (not shown) and the positional information of the slags 61a and 61b detected by the encoders 75a and 75b. The impedance is adjusted by sending a signal and controlling the positions of the slugs 61a and 61b. The slug controller 68 performs impedance matching so that the termination is, for example, 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.

  The antenna unit 45 has a planar slot antenna 81 that functions as a microwave radiation antenna and has a planar shape and has a slot 81a. The antenna unit 45 includes a slow wave material 82 provided on the upper surface of the planar slot antenna 81. A cylindrical member 82 a made of a conductor passes through the center of the slow wave member 82 to connect the bearing portion 67 and the planar slot antenna 81. Therefore, the inner conductor 53 is connected to the planar slot antenna 81 via the bearing portion 67 and the cylindrical member 82a. A slow wave member 83 is disposed on the front end side of the planar slot antenna 81. The lower end of the outer conductor 52 extends to the planar slot antenna 81, and the periphery of the slow wave material 82 is covered with the outer conductor 52. The periphery of the planar slot antenna 81 and the slow wave member 83 is covered with a covered conductor 84.

  The slow wave materials 82 and 83 have a dielectric constant larger than that of vacuum, and are made of, for example, fluorine resin or polyimide resin such as quartz, ceramics, polytetrafluoroethylene, etc. Therefore, the antenna has a function of shortening the wavelength of the microwave to make the antenna smaller. The slow wave members 82 and 83 can adjust the phase of the microwave depending on the thickness thereof, and the thickness thereof is adjusted so that the planar slot antenna 81 becomes a “wave” of a standing wave. Thereby, reflection can be minimized and the radiation energy of the planar slot antenna 81 can be maximized.

  The slow wave member 83 is provided in contact with the dielectric member 110b fitted into the frame 110a of the top plate 110. Then, the microwave amplified by the main amplifier 48 passes between the peripheral walls of the inner conductor 53 and the outer conductor 52, and passes through the slow wave member 83 and the dielectric member 110 b of the top plate 110 from the slot 81 a of the planar slot antenna 81. To the space in the chamber 1.

  In the present embodiment, the main amplifier 48, the tuner 60, and the planar slot antenna 81 are arranged close to each other. The tuner 60 and the planar slot antenna 81 constitute a lumped constant circuit existing within a half wavelength, and the combined resistance of the planar slot antenna 81 and the slow wave members 82 and 83 is set to 50Ω. Therefore, the tuner 60 is directly tuned with respect to the plasma load, and can efficiently transmit energy to the plasma.

  Each component in the surface wave plasma processing apparatus 100 is controlled by a control unit 120 including a microprocessor. The control unit 120 includes a storage unit that stores a process sequence of the surface wave plasma processing apparatus 100 and a process recipe that is a control parameter, an input unit, a display, and the like, and controls the plasma processing apparatus in accordance with the selected process recipe. It has become.

Next, the operation in the surface wave 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 gas, for example, Ar gas, into the chamber 1 from the plasma gas supply source 27 through the pipe 28 and the plasma gas introduction member 26, a microwave is introduced into the chamber 1 from the microwave plasma source 2. A surface wave plasma is generated.

After generating the surface wave plasma in this manner, 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 the waveguide 44 of the microwave introduction mechanism 43, so that the tuner In the state where impedance is automatically matched at 60 and there is substantially no power reflection, the chamber is passed through the slow wave member 82 of the antenna unit 45, the planar slot antenna 81, the slow wave member 83, and the dielectric member 110b of the top plate 110. 1 is radiated into 1 and is spatially synthesized.

  At this time, when the input phases of the microwaves input to the plurality of microwave introduction mechanisms 43 are all fixed at, for example, 0 °, standing waves generated when the microwaves are radiated into the chamber 1. Since the positions of the antinodes and nodes of the substrate are fixed, this causes localization of the electron density of the plasma and deteriorates the uniformity of the plasma density distribution.

  For this reason, in the present embodiment, for the adjacent ones of the plurality of microwave introduction mechanisms 43, the input phase of one microwave is fixed, and the input phase of the other microwave is changed by a periodic waveform such as a sine wave. Let Alternatively, the microwave input phases of the adjacent microwave introduction mechanisms 43 are changed by a periodic waveform that does not overlap each other.

  For example, with respect to the three microwave introduction mechanisms 43 shown by hatching in FIG. 8, the input phase of the microwave is changed according to a periodic waveform, and the input phase of the remaining hollow microwave introduction mechanisms 43 is set to 0 °. Fix it. Accordingly, the microwave input phase in the adjacent microwave introduction mechanism 43 at that time is as shown in FIG. 9 when a periodic waveform is a sine wave. And the part which became the antinode of the standing wave when the input phases of the microwaves of the adjacent microwave introduction mechanisms 43 are both 0 ° becomes a node when one input phase is shifted by 180 °, and becomes a node. The part that was supposed to become belly. Therefore, by periodically changing the input phase in this way, the positions of the nodes and antinodes of the standing wave are continuously changed, the electric field strength is averaged, and the in-plane uniformity of the electric field strength can be improved. . Therefore, it is possible to perform uniform plasma processing by making the electron density in the chamber 1, that is, the plasma density uniform.

  At this time, the phase of the microwave input to each microwave introduction mechanism 43 is adjusted by the phase shifter 46 of each antenna module 41. Each phase shifter 46 is controlled by the control unit 120.

  The periodic waveform is not limited to a sine wave, and various waveforms such as a triangular wave shown in FIG. 10A and a trapezoidal wave shown in FIG. 10B can be used. Further, not only a perfect sine wave but, for example, when it is desired to increase the time when the phase is around 180 °, as shown in (c), the sine wave conforms to a sine wave flattened around the phase of 180 °. It can also be a waveform (sine waveform). Although a rectangular wave can also be applied, it is not preferable because there is a portion where the differential value becomes infinite.

  Using a plasma source in which seven microwave introduction mechanisms as shown in FIG. 3 are actually used, the microwave input phase of all microwave introduction mechanisms is set to 0 °, and the six microwave introduction mechanisms on the outer periphery. The electric field distribution in the chamber was grasped when the three input phases were changed to 180 °. Here, the pressure in the chamber was 0.5 Torr, and the microwave power was 200 W. The result is shown in FIG. FIG. 11A shows the electric field distribution when the microwave input phase of all the microwave introduction mechanisms is 0 °, and FIG. 11B shows the microwaves of the three microwave introduction mechanisms on the outer periphery. It shows the electric field distribution when the input phase is changed to 180 °. FIG. 11 is a monochrome representation of the magnitude of the electric field strength represented by the difference in color, and the thin annular portion in (a) is the electric field strength around the microwave introduction mechanism in the antenna module. Is the high part and corresponds to the belly of standing waves. The darker portion is a portion with a higher electric field strength. In addition, the electric field strength is low in the portion between adjacent microwave introduction mechanisms, which corresponds to a standing wave node. A region surrounded by a broken line is a portion corresponding to a node of a standing wave. It can be seen that by changing the input phases of the three microwave introduction mechanisms to 180 °, the electric field distribution is greatly changed as shown in FIG. In (a), the part surrounded by the broken line, which was the part corresponding to the node of the standing wave, in (b), one of the two microwave introduction mechanisms sandwiching that part has a microwave input phase of 180 °. As a result, the electric field strength is increased and changes to an antinode of a standing wave. That is, when all the input phases are 0 °, the portion between the adjacent microwave introduction mechanisms 43 becomes a node of the standing wave, but the input phases of the three outer microwave introduction mechanisms 43 are changed to 180 °. By doing so, those parts are changed to a standing wave belly. From this, it is understood that if the input phase is periodically changed, the positions of antinodes and nodes of the standing wave are continuously moved, and the electric field strength is averaged. Therefore, the density of the plasma obtained by the electric field is also made uniform.

  In the present embodiment, for the adjacent ones of the plurality of microwave introduction mechanisms 43, the input phase of one microwave is fixed, and the input phase of the other microwave is changed by a periodic waveform such as a sine wave. , Or the microwave input phase of both adjacent microwave introduction mechanisms 43 is changed by a periodic waveform that does not overlap each other, but it is not necessary for all adjacent ones to satisfy such a relationship, and adjacent microwave introduction Only a part of the combinations of the mechanisms 43 may satisfy such a relationship.

<Second Embodiment>
Next, a second embodiment of the present invention will be described.
In this embodiment, the basic configuration of the microwave plasma source and the plasma processing apparatus is the same as that of the first embodiment, but the configuration of the top plate is different.

  FIG. 12 is a plan view schematically showing the microwave supply section and the top plate of the plasma source in the present embodiment, and FIG. 13 is a sectional view taken along the line CC ′ of FIG. As shown in these drawings, in the present embodiment, a circular top plate 110 is made of quartz or the like fitted into a portion where a plurality of microwave introduction mechanisms 43 for radiating microwaves into the chamber 1 are arranged. The dielectric member 110b made of a dielectric material has a hexagonal shape, and adjacent dielectric members 110b are provided close to each other so that one side of the hexagonal surface is opposed. Therefore, the metal frame 110a that supports the dielectric member 110b has a thin linear shape in the portion between the adjacent dielectric members 110b, and has a honeycomb structure. The frame 110a has a support portion 110c that supports the dielectric member 110b.

  The top plate 110 has a function of transmitting microwaves as described above, and is preferably formed of a dielectric material from the viewpoint of efficiently transmitting microwaves. However, in the case where microwaves are radiated from a plurality of microwave introduction mechanisms 43 as in the plasma source of the present embodiment, if the top plate is all formed of a dielectric material such as quartz, the microwave introduction mechanism 43. Not all of the microwaves emitted from the chamber 1 are emitted into the chamber 1, but some of the microwaves may reach the other microwave introduction mechanisms 43 through the top plate 110. In such a case, the microwave radiated from the microwave introduction mechanism 43 interferes with the microwave radiated from the other microwave introduction mechanism 43. In addition, when the top plate is made entirely of a dielectric as described above, there are problems that a mode jump of plasma is likely to occur, and that the dielectric member has no strength.

  Therefore, as in the first embodiment, in the top plate 110, the dielectric member is provided only in the portion where the microwave introduction mechanism 43 of the antenna module 41 is disposed, and the other portion supports the dielectric member. It is made of a metal frame. The dielectric member can be circular as in the first embodiment, or can be rectangular or square.

  However, when the dielectric member is circular, the area of the frame portion between adjacent dielectric members must be increased, the area occupied by the dielectric member is reduced, and the microwave radiation area is reduced. It becomes difficult to generate plasma efficiently. Further, when the dielectric member is rectangular or square, the strength of the top plate is small.

  On the other hand, the area of the dielectric member 110b occupying the top plate 110 can be maximized by making the frame 110a of the top plate 110 into a honeycomb structure and making the dielectric member hexagonal as in this embodiment. Therefore, plasma can be generated efficiently by widening the microwave irradiation region. Moreover, the strength of the top plate 110 can be ensured by making the frame 110a into a honeycomb structure in this way.

  FIG. 12 shows the case where the frame 110a has a honeycomb structure. However, the frame 110a does not necessarily have a complete honeycomb structure, but may have a structure conforming to the honeycomb structure. For example, as shown in FIG. A structure in which the outer peripheral portion of the dielectric member 110b corresponding to the wave introduction mechanism 43 projects outward can be employed. In the case of such a structure, the area of the dielectric member 110b can be increased, which is preferable. As described above, in this embodiment, the frame 110a may have a honeycomb structure including a honeycomb structure and a structure according to the honeycomb structure.

  As shown in FIG. 15, a plurality of gas discharge ports 112 may be provided in the frame 110a of the top plate 110 so that plasma gas such as Ar is supplied in a shower shape. In this case, a gas flow path is formed inside the frame 110a of the top plate 110, and a plasma gas supply source 27 is connected to the gas flow path via, for example, a pipe 28 to discharge a plasma gas such as Ar gas. It discharges uniformly from the outlet 112. As a result, the Ar gas can be rapidly turned into plasma to generate uniform plasma.

  In addition, although this embodiment exhibits a bigger effect by combining with 1st Embodiment, of course, the said effect can be acquired even if it does not presuppose 1st Embodiment.

  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 circuit configuration of the microwave output unit, the microwave supply unit, the circuit configuration of the main amplifier, and the like are not limited to the above embodiment. Further, the microwave introduction mechanism is not limited to the structure of the above embodiment, and any structure that can appropriately radiate microwaves into the chamber may be used. Further, the number and arrangement of the microwave introduction mechanisms are not limited to the above embodiment.

  Furthermore, in the above-described embodiment, the etching processing apparatus is exemplified as the plasma processing apparatus. However, the present invention is not limited to this, and the plasma processing apparatus can be used for other plasma processing such as film formation processing, oxynitride film processing, and ashing processing. Further, the substrate to be processed is not limited to a semiconductor wafer, and may be another substrate such as an FPD (flat panel display) substrate typified by an LCD (liquid crystal display) substrate or a ceramic substrate.

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 43; 46; Phaser 52; Outer conductor 53; Inner conductor 54; Feed mechanism 60; Tuner 81; Planar slot antenna 100; Surface wave plasma processing apparatus 110; Top plate 110a; Frame 110b; Dielectric member 120;

Claims (5)

A plasma source that introduces microwaves into a processing vessel for performing plasma processing and converts the gas supplied into the processing vessel into plasma,
A microwave generation mechanism for generating a microwave;
A microwave supply unit for supplying the generated microwave into the processing container,
The microwave supply unit includes a plurality of microwave introduction mechanisms that introduce microwaves into the processing container, and a plurality of phase shifters that adjust the phases of microwaves input to the plurality of microwave introduction mechanisms, respectively. Have
Regarding the adjacent ones of the plurality of microwave introduction mechanisms, the input phase of one microwave is fixed and the input phase of the other microwave is changed by a periodic waveform, or the adjacent microwave introduction mechanisms The phase of the microwaves input to the plurality of microwave introduction mechanisms is adjusted by the plurality of phase shifters so that the input phases of both microwaves are changed by a periodic waveform that does not overlap each other. A microwave plasma source.   The microwave plasma source according to claim 1, wherein the periodic waveform is any one of a sine wave, a triangular wave, a trapezoidal wave, and a sine wave waveform.   It further comprises a top plate that constitutes the upper wall of the processing vessel and transmits microwaves radiated from the plurality of microwave introduction mechanisms, and the top plate is located at a position corresponding to the plurality of microwave introduction mechanisms. 3. A plurality of dielectric members provided, and a metal frame that supports the dielectric members, wherein the frame has a honeycomb structure. Microwave plasma source.   The said flame | frame has a gas flow path and several gas discharge holes, The gas required for a plasma process is discharged toward the said process container from the said gas discharge hole. Microwave plasma source. A processing container for storing a substrate to be processed;
A mounting table on which a substrate to be processed is mounted in the processing container;
A gas supply mechanism for supplying gas into the processing container;
A microwave plasma source according to any one of claims 1 to 4,
A plasma processing apparatus characterized in that plasma is generated by microwaves introduced into the processing container from the microwave plasma source, and processing is performed on a substrate to be processed by the plasma.