JP2018006718A - Microwave plasma processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microwave plasma processing device capable of suppressing interference of a microwave.SOLUTION: A microwave plasma processing device is provided on a microwave radiation member in a circumferential direction as a center of a central axis of the microwave radiation member while having an equivalent interval, includes a plurality of microwave introduction mechanisms formed by a microwave waveguide introducing the microwave to the microwave radiation member, and includes: a slow-wave material 121 formed by a dielectric body corresponded and provided to a region where the plurality of microwave introduction mechanisms is arranged; and a slot 123 radiating the microwave covered by the slow-wave material and introduced through the slow-wave material. The slot has a circular form as a center of the central axial of the microwave radiation member, and is formed on any one of an inner peripheral side and an outer peripheral side from the circle coupled by each central axis of the microwave waveguide with an intersection point of the microwave radiation member.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a microwave plasma processing apparatus.

  Microwaves that can adjust the phase and intensity of the microwaves introduced from each microwave introduction mechanism and adjust the plasma distribution by spatially synthesizing the microwaves using multiple microwave introduction mechanisms A wave plasma source is known (see, for example, Patent Document 1).

JP 2012-216745 A

  When the above microwave plasma source is used, if the number of microwave introduction mechanisms is small, the plasma does not spread sufficiently in the circumferential direction, and it is difficult to obtain a uniform plasma. Therefore, it is conceivable to increase the number of microwave introduction mechanisms.

  However, when the number of microwave introduction mechanisms is increased, the distance between adjacent microwave introduction mechanisms is shortened, so that the microwaves introduced from the respective microwave introduction mechanisms may interfere with each other.

  In view of the above, an object of one embodiment of the present invention is to provide a microwave plasma processing apparatus capable of suppressing microwave interference.

  In order to achieve the above object, a microwave plasma processing apparatus according to one aspect of the present invention is a microwave plasma processing apparatus that forms a surface wave plasma by radiating microwaves into a chamber that accommodates a substrate. A microwave radiating member that radiates microwaves into the chamber, and is provided on the microwave radiating member at equal intervals in the circumferential direction around the central axis of the microwave radiating member. A plurality of microwave introduction mechanisms formed by a waveguide for introducing a microwave, and the microwave radiation member includes a main body made of metal, and a side of the main body on which the microwave is introduced A slow wave material made of a dielectric material provided corresponding to a region where the plurality of microwave introduction mechanisms are disposed, and is covered with the slow wave material and introduced through the slow wave material A slot for radiating microwaves, and a microwave transmitting member made of a dielectric provided so as to cover a region where the slot is formed on the side of radiating microwaves of the main body, and the slot , A circle centering on the central axis of the microwave radiating member, the inner peripheral side and the outer peripheral side of a circle connecting the intersection of each central axis of the waveguide and the microwave radiating member At least one of them is formed.

  According to the disclosed microwave plasma processing apparatus, microwave interference can be suppressed.

The figure which shows an example of the longitudinal cross-section of the microwave plasma processing apparatus which concerns on one Embodiment The block diagram which shows an example of a structure of the microwave plasma source which concerns on one Embodiment Schematic perspective view showing an example of a peripheral microwave introduction mechanism according to an embodiment Schematic perspective view showing another example of the peripheral microwave introduction mechanism according to one embodiment The enlarged view which shows an example of the microwave radiation member which concerns on one Embodiment The figure for demonstrating an example of arrangement | positioning of a slow wave material The figure for demonstrating an example of arrangement | positioning of a slot The figure for demonstrating the other example of arrangement | positioning of a slot The figure for demonstrating the further another example of arrangement | positioning of a slot The figure which shows an example of the longitudinal cross-section of the microwave plasma processing apparatus which concerns on the modification 1 of one Embodiment. The figure which shows an example of the longitudinal cross-section of the microwave plasma processing apparatus which concerns on the modification 2 of one Embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In addition, in this specification and drawing, about the substantially same structure, the duplicate description is abbreviate | omitted by attaching | subjecting the same code | symbol.

(Overall configuration of microwave plasma processing equipment)
The microwave plasma processing apparatus 100 will be described. FIG. 1 is a diagram illustrating an example of a longitudinal section of a microwave plasma processing apparatus 100 according to an embodiment of the present invention.

  The microwave plasma processing apparatus 100 forms surface wave plasma by microwaves and performs predetermined plasma processing on a semiconductor wafer (hereinafter referred to as “wafer W”) which is an example of a substrate. As an example of the plasma process, a film forming process or an etching process is exemplified.

  The microwave plasma processing apparatus 100 includes a chamber 1 that accommodates a wafer W. The chamber 1 is a substantially cylindrical container made of a metal material such as aluminum or stainless steel that is hermetically configured and is grounded. The microwave plasma source 2 is provided so as to face the inside of the chamber 1 from an opening 1 a formed in the upper portion of the chamber 1. When microwaves are introduced into the chamber 1 by the microwave plasma source 2, surface wave plasma is formed in the chamber 1.

  A mounting table 11 on which a wafer W is mounted is provided in the chamber 1. The mounting table 11 is supported by a cylindrical support member 12 erected at the center of the bottom of the chamber 1 via an insulating member 12a. Examples of the material constituting the mounting table 11 and the support member 12 include metals such as aluminum whose surfaces are anodized (anodized) and insulating members (ceramics and the like) having high-frequency electrodes therein. The mounting table 11 may be provided with 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 like.

  A high frequency bias power source 14 is electrically connected to the mounting table 11 via a matching unit 13. By supplying high-frequency power from the high-frequency bias power source 14 to the mounting table 11, ions in the plasma are attracted to the wafer W side. Note that the high-frequency bias power source 14 may not be provided depending on the characteristics of the plasma processing. In this case, an electrode is not required even if an insulating member made of ceramics such as AlN is used as the mounting table 11.

  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. When the exhaust device 16 is operated, the inside of the chamber 1 is exhausted, and thereby the inside of the chamber 1 is depressurized at a high speed to a predetermined vacuum level. 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.

  The microwave plasma source 2 includes a microwave output unit 30, a microwave transmission unit 40, and a microwave radiation member 50. The microwave output unit 30 outputs the microwaves distributed to a plurality of paths.

  The microwave transmission unit 40 transmits the microwave output from the microwave output unit 30. The peripheral microwave introduction mechanism 43a and the central microwave introduction mechanism 43b have a function of introducing the microwave output from the amplifier unit 42 into the microwave radiation member 50 and a function of matching impedance.

  In the peripheral microwave introduction mechanism 43a and the center microwave introduction mechanism 43b, a cylindrical outer conductor 52 and a rod-shaped inner conductor 53 provided at the center thereof are arranged coaxially. Microwave power is supplied to the space between the outer conductor 52 and the inner conductor 53, and the microwave propagates toward the microwave radiating member 50.

  The peripheral microwave introduction mechanism 43a and the central microwave introduction mechanism 43b are provided with a slag 61 and an impedance adjustment member 140 located at the tip thereof. By moving the slag 61, the impedance of the load (plasma) in the chamber 1 is matched with the characteristic impedance of the microwave power source in the microwave output unit 30. The impedance adjusting member 140 is formed of a dielectric, and adjusts the impedance of the microwave transmission path 44 by its relative dielectric constant.

  The microwave radiating member 50 is provided in a state of being hermetically sealed to a support ring 29 provided at the upper portion of the chamber 1, and radiates the microwave transmitted from the microwave transmission unit 40 into the chamber 1. The microwave radiation member 50 constitutes the ceiling portion of the chamber 1.

The microwave radiation member 50 is provided with a first gas introduction part 21 having a shower structure, and a first gas supply source 22 is connected to the first gas introduction part 21 via a gas supply pipe 111. A gas for plasma generation, such as Ar gas or a gas to be decomposed with high energy, such as O ₂ gas or N ₂ gas, supplied from the first gas supply source 22 is a first gas introduction unit. 21 is supplied into the chamber 1 as a shower.

  The microwave radiation member 50 includes a main body 120, a slow wave material 121, a microwave transmission member 122, a slot 123, and a dielectric layer 124. The detailed structure of the microwave radiating member 50 will be described later.

A second gas introduction portion 23 configured as a shower plate is horizontally provided at a position between the mounting table 11 and the microwave radiation member 50 in the chamber 1. The second gas introduction part 23 has a gas flow path 24 formed in a lattice shape and a large number of gas holes 25 formed in the gas flow path 24. The space 26 is a space. A gas supply pipe 27 extending outside the chamber 1 is connected to the gas flow path 24, and a second gas supply source 28 is connected to the gas supply pipe 27. A second gas such as SiH ₄ gas or C ₅ F ₈ gas is supplied from the second gas supply source 28 to be supplied without being decomposed as much as possible during plasma processing such as film formation or etching. It comes to be supplied. In addition, as gas supplied from the 1st gas supply source 22 and the 2nd gas supply source 28, the various gas according to the content of the plasma processing can be used.

  Each part of the microwave plasma processing apparatus 100 is controlled by the control device 3. The control device 3 includes a microprocessor 4, a ROM (Read Only Memory) 5, and a RAM (Random Access Memory) 6. The ROM 5 and the RAM 6 store a process recipe that is a process sequence and control parameters of the microwave plasma processing apparatus 100. The microprocessor 4 is an example of a control unit that controls each unit of the microwave plasma processing apparatus 100 based on a process sequence and a process recipe. The control device 3 includes a touch panel 7, a display 8, and the like, and can perform input and display of results when performing predetermined control according to a process sequence and a process recipe.

  When plasma processing is performed in the microwave plasma processing apparatus 100 having such a configuration, first, the wafer W is held on the transfer arm, and then enters the chamber 1 from the opened gate valve 18 through the loading / unloading port 17. It is brought in. The gate valve 18 is closed after the wafer W is loaded. The wafer W is transferred from the transfer arm to a lift pin (not shown), and is placed on the mounting table 11 as the lift pin is lowered. The pressure in the chamber 1 is maintained at a predetermined degree of vacuum by the exhaust device 16. Gas is introduced into the chamber 1 from the first gas introduction part 21 and the second gas introduction part 23 in the form of a shower. Microwaves are introduced from the ceiling of the chamber 1 and high frequency power is applied to the mounting table 11.

  The wafer W is subjected to plasma processing by surface wave plasma generated on the surface on the chamber 1 side by the microwave radiated from the ceiling portion of the chamber 1 through the peripheral microwave introduction mechanism 43a and the central microwave introduction mechanism 43b. .

(Microwave plasma source)
The microwave plasma source 2 will be described. FIG. 2 is a block diagram showing an example of the configuration of the microwave plasma source 2 used in the microwave plasma processing apparatus 100 of FIG.

  The microwave plasma source 2 includes a microwave output unit 30, a microwave transmission unit 40, and a microwave radiation member 50. As shown in FIG. 2, 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 distribution that distributes the amplified microwave into a plurality of parts. And 34.

  The microwave oscillator 32 oscillates a microwave having a predetermined frequency (for example, 860 MHz), for example, by PLL (Phase Locked Loop). 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. As the microwave frequency, various frequencies in the range of 700 MHz to 3 GHz such as 915 MHz can be used in addition to 860 MHz.

  As shown in FIG. 1, the microwave transmission unit 40 includes a plurality of amplifier units 42, and a peripheral microwave introduction mechanism 43 a and a central microwave introduction mechanism 43 b provided corresponding to the amplifier unit 42. A plurality of peripheral microwave introduction mechanisms 43 a are provided along the circumferential direction on the peripheral portion of the microwave radiating member 50, and the central microwave introduction mechanism 43 b is provided on the central portion of the microwave radiating member 50. One is provided. The number of peripheral microwave introduction mechanisms 43a may be two or more, but is preferably three or more, for example, 3-6.

  As shown in FIG. 2, the amplifier unit 42 guides the microwave distributed by the distributor 34 to the peripheral microwave introduction mechanism 43a and the central microwave introduction mechanism 43b. 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 can modulate the radiation characteristic by changing the phase of the microwave. For example, by adjusting the phase of the microwaves introduced into the peripheral microwave introduction mechanism 43a and the central microwave introduction mechanism 43b, the directivity can be controlled to change the plasma distribution. Further, circularly polarized waves can be obtained by shifting the phase by 90 ° between adjacent microwave introduction mechanisms. 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 may not be provided when such modulation of radiation characteristics and adjustment of delay characteristics between components in the amplifier are unnecessary.

  The variable gain amplifier 47 adjusts the power level of the microwave input to the main amplifier 48 and adjusts 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 includes, for example, an input matching circuit, a semiconductor amplifying element, an output matching circuit, and a high Q resonance circuit. The isolator 49 separates the reflected microwaves that are reflected by the slot antenna portion and travel toward the main amplifier 48, and includes a circulator and a dummy load (coaxial terminator). The circulator guides the reflected microwave to the dummy load, and the dummy load converts the reflected microwave guided by the circulator into heat.

  The peripheral microwave introduction mechanism 43 a and the central microwave introduction mechanism 43 b introduce the microwave output from the amplifier unit 42 into the microwave radiation member 50.

  FIG. 3 is a schematic perspective view showing an example of the peripheral microwave introduction mechanism 43a according to the embodiment. In FIG. 3, the central microwave introduction mechanism 43b is not shown for convenience.

  As shown in FIG. 3, a plurality of peripheral microwave introduction mechanisms 43a are provided on the microwave radiating member 50 at equal intervals in the circumferential direction around the central axis C1 of the microwave radiating member 50 (chamber 1). It has been. The peripheral microwave introduction mechanism 43a includes a coaxial waveguide (hereinafter referred to as “coaxial waveguide”) that transmits microwaves. The coaxial waveguide has a cylindrical inner conductor 53 and a cylindrical outer conductor 52 provided on the outer peripheral side of the inner conductor 53 via a dielectric. In the coaxial waveguide, the inner conductor 53 is a feeding side and the outer conductor 52 is a ground side. A microwave radiation member 50 is provided at the lower end of the coaxial waveguide. The microwave is transmitted through the coaxial waveguide and guided to the microwave radiating member 50.

  FIG. 3 shows an example in which twelve peripheral microwave introduction mechanisms 43a are provided, but the number of peripheral microwave introduction mechanisms 43a is not limited to this. It is preferable that six or more peripheral microwave introduction mechanisms 43a are provided from the viewpoint that the plasma can be sufficiently spread in the circumferential direction and uniform plasma can be obtained. It is more preferable.

  FIG. 4 is a schematic perspective view showing another example of the peripheral microwave introduction mechanism 43a according to the embodiment. As shown in FIG. 4, the peripheral microwave introduction mechanism 43 a has a coaxial distributor 71 that distributes the microwaves into a plurality at the lower end portion. The coaxial distributor 71 has a cylindrical inner conductor and an outer conductor provided on the outer peripheral side of the inner conductor via a dielectric. The inner conductor and the outer conductor of the coaxial distributor 71 are electrically connected to the inner conductor 53 and the outer conductor 52 of the coaxial waveguide, respectively. The outer conductor of the coaxial distributor 71 is covered with a dielectric member 72 such as Teflon (registered trademark). The coaxial distributor 71 distributes a plurality of microwaves introduced from the amplifier unit 42 and transmitted through the coaxial waveguide 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. . The shape of the coaxial distributor 71 is not particularly limited as long as the microwave can be evenly distributed, and is appropriately set according to the wavelength of the microwave, for example. FIG. 4 shows the coaxial distributor 71 that distributes the microwaves into four. However, the present invention is not limited to this. For example, 2 can be used as long as the microwaves can be evenly distributed. You may distribute to one. As shown in FIG. 4, the peripheral microwave introduction mechanism 43 a includes the coaxial distributor 71, whereby the number of the amplifier units 42 and the like can be reduced, and the cost can be reduced.

(Microwave radiation member)
The microwave radiation member 50 will be described. FIG. 5 is an enlarged view showing an example of the microwave radiating member 50 according to the embodiment. FIG. 6 is a diagram for explaining an example of the arrangement of the slow wave material 121.

  The microwave radiating member 50 radiates the microwave output from the microwave output unit 30 and transmitted through the microwave transmission unit 40 into the chamber 1. The microwave radiating member 50 has a metal main body 120. As a metal which comprises the main-body part 120, a metal with high heat conductivity like aluminum and copper is preferable.

  The main body 120 has a peripheral portion where the peripheral microwave introduction mechanism 43a is disposed and a central portion where the central microwave introduction mechanism 43b is disposed. The peripheral portion corresponds to the peripheral region of the wafer W, and the central portion corresponds to the central region of the wafer W.

  As shown in FIG. 5 and FIG. 6, an area where a plurality of peripheral microwave introduction mechanisms 43 a are arranged on the upper part of the peripheral part of the main body part 120 (the side where the microwaves in the main body part 120 are introduced). Correspondingly, a plurality of slow wave members 121 are provided at equal intervals along the circumferential direction.

The slow wave material 121 has a dielectric constant larger than that of a vacuum, and can be formed of, for example, ceramics such as quartz and alumina (Al ₂ O ₃ ), fluorine resin such as polytetrafluoroethylene, and polyimide resin. That is, since the wavelength of the microwave becomes longer in the vacuum, the slow wave material 121 is made of a material having a dielectric constant larger than that of the vacuum, so that the wavelength of the microwave is shortened and the slot 123 is formed. It has a function to make the antenna including it small.

  On the lower surface (surface on the chamber 1 side) of the peripheral edge of the main body 120, as shown in FIG. 5, there is a microwave transmitting member 122 that forms an annular shape along a region where a plurality of slow wave members 121 are provided. Is provided. A portion of the main body 120 between the slow wave material 121 and the microwave transmitting member 122 is a slot antenna portion in which a plurality of slots 123 and a dielectric layer 124 are formed vertically.

The microwave transmitting member 122 is made of a dielectric material that is a material that transmits microwaves, and has a function of forming uniform surface wave plasma in the circumferential direction. The microwave transmitting member 122 can be formed of ceramics such as quartz and alumina (Al ₂ O ₃ ), a fluorine resin such as polytetrafluoroethylene, and a polyimide resin, as with the slow wave material 121. In addition, the microwave transmission member 122 may be divided | segmented into plurality along the circumferential direction.

  As shown in FIG. 5, the slot 123 extends from the upper surface position of the main body 120 in contact with the slow wave material 121 to the upper surface of the dielectric layer 124, and the microwave transmitted from the peripheral microwave introduction mechanism 43 a is transmitted. Determine the radiation characteristics. A region between the slow wave material 121 and the dielectric layer 124 of the main body 120 is configured as a slot antenna unit including a slot 123.

  A cylindrical member 82 is provided on the bottom plate at the tip of the microwave transmission path 44. The slot 123 has a function of mode-converting microwaves transmitted as TEM waves from the peripheral microwave introduction mechanism 43a through the cylindrical member 82 into TE waves. The microwave radiated from the slot 123 is radiated into the chamber 1 through the dielectric layer 124 and the microwave transmission member 122.

  The slot 123 may be vacuum, but is preferably filled with a dielectric. By filling the slot 123 with a dielectric, the effective wavelength of the microwave is shortened, and the thickness of the slot 123 can be reduced. As the dielectric filling the slot 123, for example, a fluorine resin such as quartz, ceramics, polytetrafluoroethylene, or a polyimide resin can be used.

  As shown in FIG. 6, the slot 123 is centered on the central axis C1 of the microwave radiating member 50 and passes through the inner conductor 53 (cylindrical member 82) at a position in contact with the microwave radiating member 50 of the coaxial waveguide. It is formed on at least one of the inner circumference side and the outer circumference side of the circle. Thereby, it can suppress that the microwave introduce | transduced from the periphery microwave introduction mechanism 43a radiates | emits to the circumferential direction of the circle | round | yen which passes the cylindrical member 82 centering on the central axis C1 of the microwave radiation member 50. FIG. That is, it can suppress that the microwave introduced from one peripheral microwave introduction mechanism 43a radiates | emits in the direction in which the other peripheral microwave introduction mechanism 43a adjacent in the circumferential direction was provided. For this reason, even if it is a case where the distance of the peripheral microwave introduction mechanism 43a adjacent in the circumferential direction is short, it can suppress that the microwaves introduced from each peripheral microwave introduction mechanism 43a mutually interfere. FIG. 6 shows a case where one slot 123 is formed around the central axis C1 of the microwave radiating member 50, one on the inner peripheral side and one on the outer peripheral side with respect to a circle passing through the cylindrical member 82. Yes.

  Hereinafter, a specific example of the slot 123 will be described.

  FIG. 7 is a view for explaining an example of the arrangement of the slots 123, and is a top view showing the arrangement of the slots 123 at the position A in FIG. In FIG. 7, the inner peripheral side is the upward direction, and the outer peripheral side is the downward direction.

As shown in FIG. 7, the slot 123 includes an inner peripheral slot 123 a formed on the inner peripheral side with respect to a circle passing through the cylindrical member 82, and an outer peripheral side formed on the outer peripheral side with respect to a circle passing through the cylindrical member 82. And a slot 123b. The inner circumferential slot 123a and the outer circumferential slot 123b are formed in an arc shape along the circumferential direction of a circle centered on the central axis C2 of the cylindrical member 82, and are symmetrical with respect to the central axis C2 of the cylindrical member 82. Has been placed. That is, the inner circumferential slot 123a and the outer circumferential slot 123b are not formed on the circumference of a circle passing through the cylindrical member 82 with the central axis C1 of the microwave radiating member 50 as the center. Thereby, the microwave introduced from the peripheral microwave introduction mechanism 43a is hardly radiated in the circumferential direction of the circle passing through the cylindrical member 82 with the central axis C1 of the microwave radiating member 50 as the center. That is, the microwave is hardly propagated in the direction of the adjacent peripheral microwave introduction mechanism 43a. As a result, the microwaves introduced from the peripheral microwave introduction mechanisms 43a can be prevented from interfering with each other. In addition, as a shape of the slow wave material 121, it can be set as a disk shape, for example. The circumferential lengths of the inner circumferential slot 123a and the outer circumferential slot 123b are preferably λg / 2 from the viewpoint of increasing the electric field strength and obtaining good efficiency. Note that λg is the effective wavelength of the microwave and can be expressed as λg = λ / ε _s ^1/2 . ε _s is the dielectric constant of the dielectric filled in the slot 123, and λ is the wavelength of the microwave in vacuum.

  FIG. 8 is a diagram for explaining another example of the arrangement of the slots 123, and is a top view showing the arrangement of the slots 123 at the position A in FIG. In FIG. 8, the inner peripheral side is the upward direction and the outer peripheral side is the downward direction.

  As shown in FIG. 8, the slot 123 includes an inner peripheral side slot 123 a formed on the inner peripheral side with respect to a circle passing through the cylindrical member 82, and an outer peripheral side formed on the outer peripheral side with respect to the circle passing through the cylindrical member 82. And a slot 123b. The inner peripheral side slot 123a and the outer peripheral side slot 123b are formed in an arc shape along the circumferential direction of a circle centering on the central axis C1 of the microwave radiating member 50. That is, the inner circumferential slot 123a and the outer circumferential slot 123b are not formed on the circumference of a circle passing through the cylindrical member 82 with the central axis C1 of the microwave radiating member 50 as the center. Thereby, the microwave introduced from the peripheral microwave introduction mechanism 43a is hardly radiated in the circumferential direction of the circle passing through the cylindrical member 82 with the central axis C1 of the microwave radiating member 50 as the center. That is, the microwave is hardly propagated in the direction of the adjacent peripheral microwave introduction mechanism 43a. As a result, the microwaves introduced from the peripheral microwave introduction mechanisms 43a can be prevented from interfering with each other. In addition, as a shape of the slow wave material 121, it can be set as a fan shape, for example. The lengths of the inner circumferential slot 123a and the outer circumferential slot 123b in the longitudinal direction are preferably λg / 2 from the viewpoint of increasing the electric field strength and obtaining good efficiency.

  FIG. 9 is a view for explaining still another example of the arrangement of the slots 123, and is a top view showing the arrangement of the slots 123 at the position A in FIG. In FIG. 9, the inner peripheral side is the upward direction and the outer peripheral side is the downward direction.

  As shown in FIG. 9, the slot 123 includes an inner peripheral slot 123 a formed on the inner peripheral side with respect to a circle passing through the cylindrical member 82, and an outer peripheral side formed on the outer peripheral side with respect to a circle passing through the cylindrical member 82. And a slot 123b. The inner peripheral side slot 123a and the outer peripheral side slot 123b are formed in a rectangular shape whose longitudinal direction is the circumferential direction of the circle centering on the central axis C1 of the microwave radiating member 50, and the central axis C2 of the cylindrical member 82 They are arranged symmetrically. That is, the inner circumferential slot 123a and the outer circumferential slot 123b are not formed on the circumference of a circle passing through the cylindrical member 82 with the central axis C1 of the microwave radiating member 50 as the center. Thereby, the microwave introduced from the peripheral microwave introduction mechanism 43a is hardly radiated in the circumferential direction of the circle passing through the cylindrical member 82 with the central axis C1 of the microwave radiating member 50 as the center. That is, the microwave is hardly propagated in the direction of the adjacent peripheral microwave introduction mechanism 43a. As a result, the microwaves introduced from the peripheral microwave introduction mechanisms 43a can be prevented from interfering with each other. In addition, as a shape of the slow wave material 121, it can be made into a rectangular shape. The lengths of the inner circumferential slot 123a and the outer circumferential slot 123b in the longitudinal direction are preferably λg / 2 from the viewpoint of increasing the electric field strength and obtaining good efficiency.

  The slot 123 only needs to be formed on at least one of the inner circumference side and the outer circumference side of the circle passing through the cylindrical member 82, and the shape and the number thereof are not limited to the above. The shape and number of the slots 123 are appropriately set according to the size of the microwave transmitting member 122 and the wavelength of the microwave.

  The plurality of dielectric layers 124 are provided corresponding to the slots 123, respectively. In the present embodiment, twelve dielectric layers 124 are provided corresponding to the twelve slots 123, respectively. Adjacent dielectric layers 124 are separated by a metal body 120. A single loop magnetic field can be formed in the dielectric layer 124 by the microwave radiated from the corresponding slot 123, so that coupling of the magnetic field loop does not occur in the microwave transmission member 122 below the dielectric layer 124. It has become. Thereby, the appearance of a plurality of surface wave modes can be prevented, and a single surface wave mode can be realized. The circumferential length of the dielectric layer 124 is preferably λg / 2 or less from the viewpoint of preventing the appearance of a plurality of surface wave modes. The thickness of the dielectric layer 124 is preferably 1 to 5 mm.

The dielectric layer 124 may be air (vacuum) or a dielectric material such as dielectric ceramics or resin. As the dielectric material, for example, ceramics such as quartz and alumina (Al ₂ O ₃ ), fluorine resins such as polytetrafluoroethylene, and polyimide resins can be used. For example, when the microwave plasma processing apparatus 100 processes a 300 mm wafer and uses alumina having a microwave wavelength of 860 MHz, a slow wave material 121, a microwave transmitting member 122, and a dielectric in the slot 123, a dielectric constant of about 10. Air (vacuum) can be suitably used as the dielectric layer 124.

  Returning to FIG. 5, a slow wave member 131 having a disk shape is provided at a portion corresponding to the central microwave introduction mechanism 43 b at the upper portion of the central portion of the main body 120, and a circular portion is provided at a portion corresponding to the slow wave member 131. A plate-shaped microwave transmitting member 132 is provided. Further, a portion of the main body 120 between the slow wave member 131 and the microwave transmitting member 132 is a slot antenna portion having a slot 133. The shape and size of the slot 133 are appropriately adjusted so as to suppress the occurrence of mode jump and to obtain a uniform electric field strength. For example, the slot 133 is formed in an annular shape. As a result, there is no seam between the slots 133, a uniform electric field can be formed, and mode jumps are less likely to occur.

  Like the slot 123, the slot 133 is preferably filled with a dielectric. As the dielectric filled in the slot 133, the same one as that used for the slot 123 can be used. In addition, as the dielectric constituting the slow wave material 131 and the microwave transmission member 132, the same materials as the above-described slow wave material 121 and the microwave transmission member 122 can be used.

  An annular groove 126 is formed on the upper surface of the main body 120 between a region where the peripheral microwave introduction mechanism 43a is provided and a region where the central microwave introduction mechanism 43b is provided. Thereby, the microwave interference between the peripheral microwave introduction mechanism 43a and the center microwave introduction mechanism 43b can be suppressed.

  The main body 120 is provided with the first gas introduction part 21 described above. The first gas introduction part 21 is formed in a concentric shape between a peripheral part having a region where the peripheral microwave introduction mechanism 43a is provided and a central part having a region where the central microwave introduction mechanism 43b is provided. The outer gas diffusion space 141 and the inner gas diffusion space 142 are provided. A gas introduction hole 143 connected to the upper surface of the main body 120 is formed on the upper surface of the outer gas diffusion space 141, and a plurality of gas holes 144 reaching the lower surface of the main body 120 are formed on the lower surface of the outer gas diffusion space 141. Is formed. On the other hand, a gas introduction hole 145 connected to the upper surface of the main body 120 is formed on the upper surface of the inner gas diffusion space 142, and a plurality of gas holes reaching the lower surface of the main body 120 are formed on the lower surface of the inner gas diffusion space 142. 146 is formed. A gas supply pipe 111 for supplying the first gas from the first gas supply source 22 is connected to the gas introduction holes 143 and 145.

(Operation of plasma processing equipment)
An operation in the microwave 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 mounting table 11. Then, a plasma generation gas such as Ar gas or a first gas to be decomposed with high energy is supplied from the first gas supply source 22 through the gas supply pipe 111 and the first gas introduction part 21 of the microwave radiating member 50. Introduce into 1.

  Plasma generation gas and processing gas are supplied from the first gas supply source 22 to the outer gas diffusion space 141 and the inner gas diffusion space 142 of the first gas introduction part 21 through the gas introduction holes 143 and 145 through the gas supply pipe 111. Then, the gas is introduced into the chamber 1 through the gas holes 144 and 146.

  On the other hand, the microwaves transmitted from the microwave output unit 30 of the microwave plasma source 2 through the plurality of amplifier units 42 and the plurality of microwave introduction mechanisms 43a and 43b of the microwave transmission unit 40 are microwave radiation members 50. Through the chamber 1. The first gas is turned into plasma by the high electric field energy of the microwave radiated to the surface of the ceiling, and surface wave plasma is generated.

  Further, a second gas such as a processing gas to be supplied from the second gas supply source 28 without being decomposed as much as possible is introduced into the chamber 1 through the gas supply pipe 27 and the second gas introduction unit 23. The second gas introduced from the second gas introduction unit is excited by the plasma of the first gas. At this time, since the second gas introduction position is a position where the energy is lower than the position away from the surface of the microwave radiating member 50, the second gas is excited in a state where unnecessary decomposition is suppressed. Then, plasma processing, for example, film formation processing or etching processing is performed on the wafer W by the plasma of the first gas and the second gas.

  At this time, the peripheral microwave introduction mechanism 43a is oscillated from the microwave oscillator 32 of the microwave output unit 30, amplified by the amplifier 33, distributed to a plurality by the distributor 34, and passed through the amplifier unit 42. Electric power is supplied. The microwave power fed to the peripheral microwave introduction mechanism 43 a is transmitted through the microwave transmission path 44 and introduced into the peripheral portion of the microwave radiation member 50. At that time, the impedance is automatically matched by the slag 61, and the microwave is introduced with substantially no power reflection. The introduced microwave passes through the slow wave material 121 and is radiated into the chamber 1 through the slot 123 of the slot antenna unit and the microwave transmitting member 122. As a result, a surface wave is formed in a corresponding portion of the lower surface of the microwave transmitting member 122 and the main body 120, and surface wave plasma is generated in a portion immediately below the microwave radiating member 50 in the chamber 1 by this surface wave.

  At this time, the slot 123 is formed on at least one of the inner peripheral side and the outer peripheral side with respect to the circle passing through the cylindrical member 82 with the central axis C1 of the microwave radiating member 50 as the center. Thereby, it can suppress that the microwave introduce | transduced from the periphery microwave introduction mechanism 43a radiates | emits to the circumferential direction of the circle | round | yen which passes the cylindrical member 82 centering on the central axis C1 of the microwave radiation member 50. FIG. That is, it can suppress that the microwave introduced from one peripheral microwave introduction mechanism 43a radiates | emits in the direction in which the other peripheral microwave introduction mechanism 43a adjacent in the circumferential direction was provided. For this reason, even if it is a case where the distance of the peripheral microwave introduction mechanism 43a adjacent in the circumferential direction is short, it can suppress that the microwaves introduced from each peripheral microwave introduction mechanism 43a mutually interfere.

  Further, on the upper surface of the main body 120, a ring-shaped groove 126 is formed between a region where the peripheral microwave introduction mechanism 43a is provided and a region where the central microwave introduction mechanism 43b is provided. Thereby, the microwave interference and mode jump between the peripheral microwave introduction mechanism 43a and the center microwave introduction mechanism 43b can be suppressed.

  Further, a microwave is introduced from the central microwave introduction mechanism 43 b into the central portion of the microwave radiating member 50. The microwave introduced from the central microwave introduction mechanism 43b passes through the slow wave member 131 and is radiated into the chamber 1 through the slot 133 of the slot antenna part and the microwave transmitting member 132, and the central part in the chamber 1 is radiated. In addition, surface wave plasma is generated. For this reason, uniform plasma can be formed over the entire wafer arrangement region in the chamber 1.

  Further, the first gas introduction part 21 is provided in the microwave radiating member 50, and the first gas is supplied from the first gas supply source 22 to the upper surface region of the chamber 1 where the microwave is radiated. Thereby, the first gas can be excited with high energy, and plasma in a state where the gas is decomposed can be formed. Further, by providing the second gas introduction part 23 at a position lower than the ceiling part of the chamber 1 and supplying the second gas, the second gas can be converted into plasma without being decomposed with lower energy. Thereby, a preferable plasma state can be formed according to the required plasma treatment.

(Microwave plasma processing apparatus according to Modification 1)
A microwave plasma processing apparatus 100A according to Modification 1 of the embodiment will be described with reference to FIG. FIG. 10 is a diagram illustrating an example of a longitudinal section of a microwave plasma processing apparatus 100A according to the first modification of the present embodiment.

  The microwave plasma processing apparatus 100A according to Modification 1 is different from the microwave plasma processing apparatus 100 according to the embodiment shown in FIG. 1 only in the mechanism of the second gas introduction unit 23. Therefore, only the mechanism of the second gas introduction part 23 will be described.

  In the present modification, the microwave radiating member 50 is provided with a second gas introduction portion 23 having a ring-shaped shower structure. A second gas supply source 28 is connected to the second gas introduction part 23 via a gas supply pipe 112.

A second gas such as SiH ₄ gas or C ₅ F ₈ gas is supplied from the second gas supply source 28 to be supplied without being decomposed as much as possible during plasma processing such as film formation or etching. It comes to be supplied. The second gas passes through the nozzle 23 a extending from the ring-shaped shower structure to the wafer W side via the gas supply pipe 112 and is supplied to a position lower than the ceiling portion of the chamber 1.

A gas for plasma generation, such as Ar gas or a gas to be decomposed with high energy, such as O ₂ gas or N ₂ gas, supplied from the first gas supply source 22 is a first gas introduction unit. 21 is supplied into the chamber 1 as a shower. As a result, the second gas can be formed into plasma without being decomposed with lower energy. Thereby, a preferable plasma state can be formed according to the required plasma treatment.

(Microwave plasma processing apparatus according to Modification 2)
A microwave plasma processing apparatus 100B according to Modification 2 of the embodiment will be described with reference to FIG. FIG. 11 is a diagram illustrating an example of a longitudinal section of a microwave plasma processing apparatus 100B according to the second modification of the present embodiment.

  In the microwave plasma processing apparatus 100B of Modification 2, the central microwave introduction mechanism 43b is not provided, but an annular microwave radiation member 50 including an arrangement region of the peripheral microwave introduction mechanism 43a is provided. In addition, a conductive shower head 150 having a size substantially the same as that of the wafer W is provided via an insulating member 151 in the central portion inside the microwave radiating member 50.

  The shower head 150 has a gas diffusion space 152 formed in a disc shape, a number of gas holes 153 formed so as to face the chamber 1 from the gas diffusion space 152, and a gas introduction hole 154. . A gas supply source 157 is connected to the gas introduction hole 154 via a gas supply pipe 158. A high frequency power source 156 for generating plasma is electrically connected to the shower head 150 via a matching unit 155. The mounting table 11 has a conductive portion and functions as a counter electrode of the shower head 150. Gases necessary for plasma processing are collectively supplied from the gas supply source 157 into the chamber 1 through the gas supply pipe 158 and the shower head 150, and high frequency power is supplied from the high frequency power source 156 to the shower head 150. As a result, a high frequency electric field is formed between the shower head 150 and the mounting table 11, and capacitively coupled plasma is formed in a space immediately above the wafer W.

  The microwave plasma processing apparatus 100 </ b> B having such a configuration is the same as the parallel plate type plasma etching apparatus that performs plasma etching on the wafer W in the central portion. For this reason, for example, it can be used as a plasma etching apparatus that adjusts the plasma density at the periphery of the wafer with surface wave plasma using microwaves. It is also possible not to provide a mechanism for generating plasma at the center.

(Experimental result)
Experimental results showing the effectiveness of the present invention will be described.

In the example, the microwave reflection characteristics and the radiation efficiency in each peripheral microwave introduction mechanism 43a when the microwave is radiated from the ceiling portion of the chamber 1 using the microwave plasma processing apparatus 100 according to the present embodiment. Calculated. In the embodiment, twelve peripheral microwave introduction mechanisms 43a (see FIG. 3) are used, and the inner peripheral side formed in an arc shape along the circumferential direction of a circle centering on the central axis C2 of the cylindrical member 82. Slots 123a and outer peripheral slots 123b (see FIG. 7) were used. Further, the radiation efficiency P _rad (%) of the microwave was calculated by the following mathematical formula (1) by calculating the reflection coefficient S (dB) in each peripheral microwave introduction mechanism 43a by simulation.

P _rad = 100 × (1-10 ^{S / 10} ) (1)
In the example, the reflection coefficient S in the twelve peripheral microwave introduction mechanisms 43a was −16.2 dB to −12.4 dB, and the radiation efficiency P _rad was 94% to 98%.

  As a comparative example, a microwave plasma processing apparatus having a slot formed in an annular shape along the circumferential direction of a circle centered on the central axis C2 of the cylindrical member 82 was used. That is, in the comparative example, slots are also formed on the circumference of a circle passing through the cylindrical member 82 with the central axis C1 of the microwave radiating member 50 as the center. Other configurations are the same as those in the example. Similarly to the example, the microwave reflection characteristics and the radiation efficiency in each peripheral microwave introduction mechanism 43a when the microwave was radiated from the ceiling portion of the chamber 1 were calculated.

  In the comparative example, the reflection coefficient S in the twelve peripheral microwave introduction mechanisms 43a was −1.51 dB to −1.35 dB, and the radiation efficiency Prad was 27% to 29%.

  Thus, according to the microwave plasma processing apparatus 100 according to the present embodiment, the microwaves introduced from the peripheral microwave introduction mechanisms 43a can be prevented from interfering with each other, and the microwave radiation efficiency can be increased. it can.

  As described above, according to the microwave plasma processing apparatuses 100, 100 </ b> A, and 100 </ b> B of the present embodiment, the slot 123 is centered on the central axis C <b> 1 of the microwave radiating member 50 and is more than the circle passing through the column member 82. It is formed on at least one of the inner peripheral side and the outer peripheral side. Thereby, even if it is a case where the distance of the peripheral microwave introduction mechanism 43a adjacent in the circumferential direction is short, it can suppress that the microwaves introduced from each peripheral microwave introduction mechanism 43a mutually interfere.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims.・ Change is possible.

  In the above embodiment, the case where the peripheral microwave introduction mechanism 43a has a coaxial waveguide for transmitting microwaves has been described as an example. However, the present invention is not limited to this and is replaced with a coaxial waveguide. It may be a rectangular waveguide. In this case, the slot 123 is a circle centered on the central axis C1 of the microwave radiating member 50, and is inward of the circle formed by connecting the intersection of each central axis of the waveguide and the microwave radiating member 50. It is formed on at least one of the circumferential side and the outer circumferential side.

  In the above embodiment, the film forming apparatus and the etching apparatus are exemplified as the microwave plasma processing apparatus. However, the present invention is not limited thereto, and the oxynitride film forming process including the oxidation process and the nitriding process, the ashing process, etc. It can also be used for other plasma treatments.

  The substrate is not limited to the wafer W, 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 3 Control apparatus 11 Mounting stand 21 1st gas introduction part 22 1st gas supply source 23 2nd gas introduction part 28 2nd gas supply source 30 Microwave output part 40 Microwave transmission part 43a Perimeter micro Wave introduction mechanism 43b Central microwave introduction mechanism 44 Microwave transmission path 50 Microwave radiation member 52 Outer conductor 53 Inner conductor 61 Slag 71 Coaxial distributor 72 Dielectric member 100 Microwave plasma processing apparatus 120 Main body 121 Slow wave material 122 Micro Wave transmission member 123 Slot 123a Inner peripheral side slot 123b Outer peripheral side slot 124 Dielectric layer 140 Impedance adjusting member

Claims (8)

A microwave plasma processing apparatus that forms surface wave plasma by radiating microwaves into a chamber that accommodates a substrate,
A microwave radiating member that radiates microwaves into the chamber;
A plurality of waveguides that are provided on the microwave radiating member at equal intervals in the circumferential direction around the central axis of the microwave radiating member, and that introduce a microwave into the microwave radiating member. Microwave introduction mechanism,
Have
The microwave radiating member includes a main body made of metal and a dielectric provided corresponding to a region where the plurality of microwave introduction mechanisms are arranged on the side of the main body where the microwave is introduced. A slow wave material, a slot that is covered with the slow wave material and emits microwaves introduced through the slow wave material, and a region where the slot is formed on the microwave radiation side of the main body is covered. A microwave transmitting member made of a dielectric material provided as follows:
The slot is a circle having a central axis of the microwave radiating member as a center, and an inner peripheral side of a circle formed by connecting an intersection of each central axis of the waveguide and the microwave radiating member; Formed on at least one of the outer peripheral sides,
Microwave plasma processing equipment. The waveguide is a coaxial waveguide having an inner conductor and an outer conductor provided via a dielectric on the outer peripheral side of the inner conductor,
A circle centered on the central axis of the microwave radiating member is a circle passing through the inner conductor at a position in contact with the microwave radiating member of the coaxial waveguide.
The microwave plasma processing apparatus according to claim 1. The microwave introduction mechanism includes a distributor that distributes the microwaves to a plurality of waveguides.
The microwave plasma processing apparatus according to claim 1 or 2. The slot includes an inner peripheral slot formed on the inner peripheral side of a circle formed by connecting an intersection of each central axis of the waveguide and the microwave radiating member, and a center of each of the waveguides. An outer peripheral side slot formed on the outer peripheral side of the circle formed by connecting the intersection of the shaft and the microwave radiating member,
The microwave plasma processing apparatus according to any one of claims 1 to 3. The inner circumferential slot and the outer circumferential slot are arranged symmetrically with respect to the central axis of the waveguide.
The microwave plasma processing apparatus according to claim 4. The inner circumferential slot and the outer circumferential slot are formed in an arc shape along a circumferential direction of a circle centered on the central axis of the waveguide.
The microwave plasma processing apparatus according to claim 4 or 5. The inner peripheral side slot and the outer peripheral side slot are formed in a rectangular shape whose longitudinal direction is the circumferential direction of a circle centering on the central axis of the microwave radiating member,
The microwave plasma processing apparatus according to claim 4 or 5. The inner circumferential slot and the outer circumferential slot are formed in an arc shape along a circumferential direction of a circle centering on a central axis of the microwave radiating member,
The microwave plasma processing apparatus according to claim 4.

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