JP6700128B2 - Microwave plasma processing equipment - Google Patents

Description

  The present invention relates to a microwave plasma processing device.

  The microwave plasma processing apparatus is capable of uniformly forming high-density surface wave plasma having a low electron temperature as compared with a parallel plate type plasma processing apparatus. In the microwave plasma processing apparatus, microwaves are radiated from the ceiling of the chamber into the chamber via a plurality of microwave introduction mechanisms. Surface wave plasma is generated on the surface of the chamber-side ceiling portion by the radiated microwaves, and the substrate is subjected to plasma treatment by the surface wave plasma (see, for example, Patent Documents 1 and 2). In Patent Documents 1 and 2, a microwave transmission window made of a dielectric is provided for each microwave introduction mechanism at the ceiling of the chamber, and microwaves are radiated into the chamber through the microwave transmission window.

International Publication No. 2008/013112 Pamphlet JP 2012-216745 A

  However, in such a configuration, there may be a problem that the plasma does not spread sufficiently in the circumferential direction and the plasma becomes nonuniform.

  With respect to the above-mentioned problem, in one aspect, the present invention aims to enhance controllability of electric field intensity distribution in a chamber.

  In order to solve the above problems, according to one aspect, a chamber that accommodates a substrate and a microwave radiating member that radiates microwaves in the chamber are provided, and the substrate is plasma-treated by surface wave plasma. In the microwave plasma processing apparatus, the microwave radiating member is a metal main body portion, and a dielectric slow-wave member that is formed on the side of the main body portion where microwaves are introduced and that transmits microwaves. A plurality of slots that are formed on the lower surface of the wave retarding material and radiate the microwaves that have propagated through the wave retarding material, and are formed in a ring-shaped exposure on the chamber surface in the main body, and the microwaves are introduced into the chamber. A dielectric microwave transmitting member to be transmitted, and a dielectric layer provided between the plurality of slots and the microwave transmitting member for propagating the microwave radiated from the plurality of slots to the microwave transmitting member. And a microwave plasma processing apparatus in which the inner edge of the microwave transmitting member is arranged on the outer peripheral side of the outer edges of the plurality of slots.

  According to one aspect, the controllability of the electric field intensity distribution in the chamber can be enhanced.

The figure which shows an example of the vertical cross section of the microwave plasma processing apparatus which concerns on one Embodiment. The figure which shows an example of a structure of the microwave plasma source which concerns on one Embodiment. The enlarged view which shows an example of the microwave radiating member which concerns on one Embodiment. FIG. 4 is a sectional view taken along line AA of FIG. The figure which shows the modification of FIG. BB sectional drawing of FIG. The figure for demonstrating distribution of the microwave electric power by the slow wave material which concerns on one Embodiment. The figure which shows typically an example of the electric field intensity distribution by the microwave transmission member which concerns on one Embodiment. The figure which shows an example of arrangement|positioning of the microwave transmission member and electric field intensity distribution which concern on one Embodiment. 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 vertical cross section of the microwave plasma processing apparatus which concerns on the modification 2 of one Embodiment.

  Embodiments for carrying out the present invention will be described below with reference to the drawings. In this specification and the drawings, substantially the same configurations will be denoted by the same reference numerals, and redundant description will be omitted.

[Whole structure of microwave plasma processing apparatus]
FIG. 1 shows an example of a cross-sectional view of a microwave plasma processing apparatus 100 according to an embodiment of the present invention. 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 processing apparatus 100 forms surface wave plasma by microwaves and performs predetermined plasma processing on a semiconductor wafer W (hereinafter, referred to as “wafer W”) which is an example of a substrate. A film forming process or an etching process is exemplified as an example of the plasma process.

  The microwave plasma processing apparatus 100 has a chamber 1 that houses a wafer W therein. The chamber 1 is a substantially cylindrical container made of an airtight metal material such as aluminum or stainless steel, and is grounded. The microwave plasma source 2 is provided so as to face the inside of the chamber 1 through 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 the wafer W is mounted is provided in the chamber 1. The mounting table 11 is supported by a cylindrical support member 12 which is erected at the center of the bottom of the chamber 1 via an insulating member 12a. Examples of the material of the mounting table 11 and the support member 12 include a metal such as aluminum whose surface is anodized (anodized), or an insulating member (ceramics or the like) having a high-frequency electrode inside. 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 a gas for heat transfer to the back surface of the wafer W, and the like.

  A high frequency bias power supply 14 is electrically connected to the mounting table 11 via a matching unit 13. By supplying high-frequency power to the mounting table 11 from the high-frequency bias power source 14, the ions in the plasma are attracted to the wafer W side. The high frequency bias power source 14 may not be provided depending on the characteristics of plasma processing.

  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, so that the inside of the chamber 1 is quickly depressurized to a predetermined degree of vacuum. The sidewall of the chamber 1 is provided with a loading/unloading port 17 for loading/unloading the wafer W and a gate valve 18 for opening/closing the loading/unloading port 17.

  The microwave plasma source 2 has a microwave output unit 30, a microwave transmission unit 40, and a microwave radiating member 50. The microwave output unit 30 outputs microwaves by dividing the microwaves into a plurality of paths.

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

  The peripheral microwave introducing mechanism 43a and the center microwave introducing mechanism 43b coaxially arrange the cylindrical outer conductor 52 and the rod-shaped inner conductor 53 provided at the center thereof. Microwave power is supplied to the space between the outer conductor 52 and the inner conductor 53, and serves as a microwave transmission path 44 through which microwaves propagate toward the microwave radiating member 50.

  The peripheral microwave introducing mechanism 43a and the central microwave introducing mechanism 43b are provided with a slug 61 and an impedance adjusting member 140 located at the tip thereof. By moving the slug 61, it has a function of matching the impedance of the load (plasma) in the chamber 1 with the characteristic impedance of the microwave power source in the microwave output section 30. The impedance adjusting member 140 is made of a dielectric material, and adjusts the impedance of the microwave transmission path 44 by its relative permittivity.

  The microwave radiating member 50 is provided in an airtightly sealed state on a support ring 29 provided on the upper portion of the chamber 1, and radiates the microwave transmitted from the microwave transmitting unit 40 into the chamber 1. The microwave radiating member 50 constitutes the ceiling portion of the chamber 1.

The microwave radiating member 50 is provided with a first gas introduction part 21 having a shower structure, and the first gas introduction part 21 is connected to a first gas supply source 22 via a gas supply pipe 111. The first gas supplied from the first gas supply source 22 passes through the first gas introduction part 21 and is supplied into the chamber 1 in a shower shape. The first gas introduction unit 21 is an example of a first gas shower head that supplies the first gas at a first height from a plurality of gas holes formed in the ceiling of the chamber 1. Examples of the first gas include a gas for plasma generation such as Ar gas and a gas to be decomposed with high energy such as O ₂ gas and N ₂ gas.

  The microwave radiating member 50 has a main body 120, a slow wave material 121, a microwave transmitting member 122, a slot 123, and a dielectric layer 124. The body 120 is made of metal. The slow wave material 121 is formed of a dielectric, is formed on the side of the main body 120 into which the microwave is introduced, and transmits the microwave. The slot 123 is a slit formed on the lower surface of the slow wave material 121, and radiates the microwave propagated through the slow wave material 121. The microwave transmission member 122 is formed of a dielectric material, is exposed in a ring shape on the surface of the chamber 1 in the main body 120, and transmits microwaves into the chamber 1. The dielectric layer 124 propagates the microwave radiated from the plurality of slots 123 to the microwave transparent member 122 between the plurality of slots 123 and the microwave transparent member 122. The inner edge of the microwave transmitting member according to the present embodiment is arranged on the outer peripheral side of the outer edges of the plurality of slots 123.

A second gas introducing unit 23 configured as a shower plate is horizontally provided in the chamber 1 at a position between the mounting table 11 and the microwave radiating member 50 in the chamber 1. The second gas introducing unit 23 has a gas passage 24 formed in a lattice shape and a large number of gas holes 25 formed in the gas passage 24. It is a space 26. A gas supply pipe 27 extending to the outside of 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. From the second gas supply source 28, a processing gas to be supplied without being decomposed as much as possible during plasma processing such as film forming processing and etching processing, for example, a second gas such as SiH ₄ gas or C ₅ F ₈ gas is supplied. It is being supplied. The 2nd gas introduction part 23 is an example of the 2nd gas shower head which supplies the 2nd gas from a plurality of gas holes with the 2nd height lower than the 1st height which supplies the 1st gas. The first gas introducing unit 21 and the second gas introducing unit 23 are an example of a gas supply mechanism that supplies gas from the gas shower head into the chamber 1. As the gas supplied from the first gas supply source 22 and the second gas supply source 28, various gases can be used according to the content of the plasma processing.

  Each unit 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, a RAM (Random Access Memory) 6, and the like. The ROM 5 and the RAM 6 store a process sequence of the microwave plasma processing apparatus 100 and a process recipe that is a control parameter. The microprocessor 4 is an example of a control unit that controls each unit of the microwave plasma processing apparatus 100 based on the process sequence and the process recipe. Further, the control device 3 has a touch panel 7, a display 8 and the like, and is capable of inputting and displaying results when performing predetermined control according to the process sequence and process recipe.

  When performing the plasma processing in the microwave plasma processing apparatus 100 having such a configuration, first, the wafer W is loaded into the chamber 1 from the opened gate valve 18 through the loading/unloading port 17 while being held on the transport arm. To be done. The gate valve 18 is closed after the wafer W is loaded. The wafer W is transferred from the transfer arm to the pusher pin, and the pusher pin descends to place it on the mounting table 11. The pressure in the chamber 1 is maintained at a predetermined vacuum degree by the exhaust device 16. The first gas is introduced into the chamber 1 in a shower shape from the first gas introducing section 21, and the second gas is introduced into the chamber 1 in a shower shape from the second gas introducing section 23. The surface waves generated on the surface of the chamber by the first and second gases being decomposed by the microwaves radiated from the microwave radiating member 50 via the peripheral microwave introducing mechanism 43a and the central microwave introducing mechanism 43b. Plasma processing is performed on the wafer W by plasma.

(Microwave plasma source)
The microwave plasma source 2 has a microwave output unit 30, a microwave transmission unit 40, and a microwave radiating member 50. As shown in FIG. 2, the microwave output unit 30 includes a microwave power supply 31, a microwave oscillator 32, an amplifier 33 that amplifies the oscillated microwave, and a distributor that distributes the amplified microwave into a plurality of parts. 34 and.

  The microwave oscillator 32 oscillates a microwave of a predetermined frequency (for example, 860 MHz), for example, PLL (Phase Locked Loop). In the distributor 34, the microwaves amplified by the amplifier 33 are distributed while impedance matching between the input side and the output side is ensured so that microwave loss does not occur as much as possible. As the microwave frequency, other than 860 MHz, various frequencies such as 915 MHz in the range of 700 MHz to 3 GHz can be used.

  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 center microwave introduction mechanism 43 b provided corresponding to the amplifier units 42. The peripheral microwave introducing mechanism 43a is provided in a plurality (for example, six) along the circumferential direction on the peripheral portion of the microwave radiating member 50, and the central microwave introducing mechanism 43b is the center of the microwave radiating member 50. One is provided on the section. The number of peripheral microwave introduction mechanisms 43a may be two or more, but is preferably three or more, and may be, for example, 3 to 6.

  As shown in FIG. 2, the amplifier section 42 guides the microwaves distributed by the distributor 34 to the peripheral microwave introducing mechanism 43a and the central microwave introducing mechanism 43b. The amplifier section 42 includes a phase shifter 46, a variable gain amplifier 47, a main amplifier 48 that constitutes 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, the directivity can be controlled and the plasma distribution can be changed by adjusting the phases of the microwaves introduced into the peripheral microwave introduction mechanism 43a and the central microwave introduction mechanism 43b. Further, circularly polarized waves can be obtained by shifting the phases by 90° in the adjacent microwave introduction mechanisms. Further, the phase shifter 46 can be used for the purpose of adjusting the delay characteristic between the components in the amplifier and for spatial synthesis in the tuner. However, the phase shifter 46 may not be provided when it is not necessary to modulate the radiation characteristic or adjust the delay characteristic between the components in the amplifier.

  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, a distribution can be generated in the generated plasma.

  The main amplifier 48 forming the solid-state amplifier has, 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 reflected by the slot antenna section toward the main amplifier 48, and has a circulator and a dummy load (coaxial terminator). The circulator guides the reflected microwaves to the dummy load, which converts the reflected microwaves guided by the circulator into heat. The peripheral microwave introducing mechanism 43a and the central microwave introducing mechanism 43b introduce the microwave output from the amplifier section 42 into the microwave radiating member 50.

(Microwave radiating member)
Next, the microwave radiating member 50 will be described with reference to FIGS. 3 and 4. FIG. 3 shows an example of a cross section showing a main part of the microwave radiating member 50. FIG. 4 shows a cross section taken along the line AA of FIG.

  The microwave radiating member 50 radiates the microwave output from the microwave output unit 30 and transmitted by the microwave transmission unit 40 into the chamber 1. The microwave radiating member 50 has a metal main body 120. The body 120 is preferably formed of a metal having a high thermal conductivity such as aluminum or copper.

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

On the upper part of the peripheral portion of the main body portion 120 (on the side where the microwave is introduced in the main body portion 120), a ring-shaped peripheral microwave introduction mechanism arrangement region including the arrangement portion of the peripheral microwave introduction mechanism 43a is formed. The slow wave material 121 forming the is fitted. The slow wave material 121 is formed of a dielectric that transmits microwaves. The slow wave material 121 has a relative dielectric constant larger than that of vacuum, and is formed of, for example, quartz, ceramics such as alumina (Al ₂ O ₃ ) or the like, fluorine resin such as polytetrafluoroethylene, or polyimide resin. obtain. That is, since the wavelength of microwaves becomes longer in vacuum, the slow wave material 121 is made of a material having a relative dielectric constant larger than that of vacuum, thereby shortening the wavelength of microwaves and including the slot 123. Has the function of reducing

  A ring-shaped microwave transmitting member 122 provided along the peripheral microwave introducing mechanism arrangement region is fitted to the lower surface (surface on the chamber 1 side) of the peripheral edge of the main body 120. A plurality of slots 123 and a dielectric layer 124 are formed in a portion of the main body 120 between the slow wave material 121 and the microwave transmission member 122.

The microwave transmitting member 122 is made of a dielectric material that is a material that transmits microwaves, is exposed to the chamber 1 side in a ring shape, and is a dielectric window for forming uniform surface wave plasma in the circumferential direction. Has the function of. The microwave transmitting member 122 may be formed of, for example, a ceramic such as quartz or alumina (Al ₂ O ₃ ), a fluorine resin such as polytetrafluoroethylene, or a polyimide resin, like the slow wave material 121. The microwave transmission member 122 may be divided into a plurality along the circumferential direction.

  As shown in FIG. 3, the slot 123 extends from a position in contact with the lower surface of the slow wave material 121 of the main body 120 to the upper surface of the dielectric layer 124, and radiates the microwave transmitted from the peripheral microwave introducing mechanism 43a. Determine the characteristics. A region between the slow wave material 121 and the dielectric layer 124 of the main body portion 120 is a slot antenna portion including the slot 123. The inner edge of the microwave transmitting member 122 is arranged on the outer peripheral side of the outer edges of the plurality of slots 123.

  A columnar 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 the microwave transmitted as the TEM wave from the peripheral microwave introducing mechanism 43a through the cylindrical member 82 into the TE wave. Then, the microwave radiated from the slot 123 is radiated into the chamber 1 through the dielectric layer 124 and the microwave transmitting member 122 in a single mode of TE wave.

  Referring to FIG. 4 showing the AA cross section of FIG. 3, the plurality of slots 123 are separated by the metal portion 120 a of the main body 120 and are evenly arranged in an arc shape having the same diameter. The microwave radiation characteristics are determined by the shape and arrangement of the slots 123. By thus providing the plurality of arc-shaped slots 123 in a circular shape as a whole, an electric field is made uniform. It can be dispersed.

  Although FIG. 4 shows an example in which twelve arc-shaped slots 123 are provided in a line on the circumference, the shape and number of the slots 123 are not limited to this, and the size and the microwave of the microwave transmission member 122 are not limited thereto. Is appropriately set according to the wavelength of. For example, FIG. 5 shows, as a modified example, an example in which six arcuate slots 123 are circumferentially provided in a row.

  The inside of the slot 123 may be vacuum or may be filled with a Teflon (registered trademark) dielectric. By filling the slot 123 with a dielectric, the effective wavelength of the microwave can be shortened, and the thickness of the slot can be reduced.

  The length of one slot 123 in the circumferential direction (longitudinal direction) is preferably slot λg/2 from the viewpoint of increasing the electric field strength and obtaining good efficiency. Here, λg is the effective wavelength of the microwave and can be expressed by the following equation (1).

ε_ｓはスロット１２３に充填される誘電体の比誘電率であり、λは真空中のマイクロ波の波長である。また、λｃはカットオフ波長であり、ＴＥ０１モードで給電する場合、空洞共振器の長手方向の長さをａとして、
λ_ｃ＝２ａ
と表される。

ε _s is the relative permittivity of the dielectric filled in the slot 123, and λ is the wavelength of the microwave in vacuum. Further, λc is a cutoff wavelength, and when feeding in the TE01 mode, the length of the cavity resonator in the longitudinal direction is a,
λ _c =2a
Is expressed as

  Considering the fine adjustment component δ (including 0) that finely adjusts so that the electric field strength becomes higher in the circumferential direction, the circumferential length of the slot 123 is preferably (λg/2)−δ. .

  The slot 123 is provided in the radial center of the slow wave material 121 and the microwave transmitting member 122, but the peripheral microwave introduction mechanism 43a is provided inside the radial center. This is because the electric field is evenly distributed on the inner side and the outer side in consideration of the difference in length between the inner circumference and the outer circumference of the slow wave material 121.

  Referring to FIG. 6 showing a cross section taken along the line BB of FIG. 4, the dielectric layers 124 are provided under the slots 123 in a one-to-one correspondence. In the example of FIG. 4, 12 dielectric layers 124 are provided for each of the 12 slots 123. Adjacent dielectric layers 124 are separated by a metal portion 120a of the metal body 120. In the dielectric layer 124, a magnetic field of a single loop can be formed by the microwave radiated from the corresponding slot 123, and the coupling of the magnetic field loop does not occur in the microwave transmitting member 122 thereunder. Is becoming This can prevent a plurality of surface wave modes from appearing and realize a single surface wave mode. The length in the circumferential direction 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. Further, the thickness of the dielectric layer 124 is preferably 1 mm to 5 mm.

  The dielectric layer 124 may be air (vacuum), or may be a dielectric material such as dielectric ceramics or resin. Examples of the dielectric material include quartz, ceramics, and fluorine such as polytetrafluoroethylene. Resins and polyimide resins can be used. The microwave plasma processing apparatus 100 processes a wafer having a diameter of 300 mm, the wavelength of the microwave is 860 MHz, and the slow wave material 121, the microwave transmission member 122, or alumina having a relative dielectric constant of about 10 is used as the dielectric in the slot 123. When used, an air layer (vacuum layer) can be preferably used as the dielectric layer 124.

  Returning to FIG. 3, the disc-shaped slow-wave member 131 is fitted in the central microwave introduction mechanism arrangement region corresponding to the central microwave introduction mechanism 43b at the upper part of the central portion of the main body 120, and the slow-wave member 131 is inserted. A microwave transmitting member 132 having a disk shape is fitted in a portion corresponding to. The portion of the main body portion 120 between the slow wave material 131 and the microwave transmitting member 132 is a slot antenna portion having the slot 133. The shape and size of the slot 133 are appropriately adjusted so as to suppress the occurrence of mode jump and obtain uniform electric field strength. For example, the slot 133 is formed in a ring shape. As a result, there is no joint between slots, 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 material. The same dielectric material as that used for the slot 123 can be used as the dielectric material with which the slot 133 is filled. Further, as the dielectric material forming the slow wave material 131 and the microwave transmission member 132, the same materials as the slow wave material 121 and the microwave transmission member 122 described above can be used.

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

  Further, the main body part 120 is provided with the above-described first gas introduction part 21. The first gas introduction part 21 is formed in an annular shape between a peripheral part having a peripheral microwave introduction mechanism arrangement region and a central part having a central microwave introduction mechanism arrangement region, and is formed as a concentric outer gas diffusion space 141. And an inner gas diffusion space 142. A gas introduction hole 143 is formed on the upper surface of the outer gas diffusion space 141 and connected to the upper surface of the main body 120, 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. Has been 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.

(Distribution of microwave power)
FIG. 7 shows the arrangement of the slots 123 and the distribution of microwave power in the peripheral portion of the microwave radiating member 50. As shown in FIG. 7, the peripheral microwave introducing mechanism 43 a is arranged so as to straddle between the two slow wave materials 121. That is, in the example of FIG. 4, the twelve slow wave materials 121 are arranged so as to extend to both sides from the positions corresponding to the six peripheral microwave introducing mechanisms 43a, respectively. In the example of FIG. 5, the six slow-wave members 121 are arranged so as to extend to both sides from the positions corresponding to the three peripheral microwave introducing mechanisms 43a.

  As described above, since the metal portion 120a of the main body 120 is arranged immediately below the peripheral microwave introducing mechanism 43a, the microwave power transmitted through the peripheral microwave introducing mechanism 43a is separated by the metal portion 120a. And is equally distributed to the slow wave material 121 on both sides thereof. As a result, microwaves, to which electric power is evenly distributed, are radiated from each slot 123.

  The microwave transmitted as the TEM wave from the peripheral microwave introducing mechanism 43a is mode-converted into the TE wave in the slot 123, is transmitted through the dielectric layer 124 as the transmission path, and is transmitted from the microwave transmitting member 122 into the chamber 1. Is emitted.

(Dielectric layer)
When the effective wavelength of the microwave of the dielectric layer 124 (vacuum) is λ, the dielectric layer 124 has a length of (λ/2)×n (n≧1) in the circumferential direction. It is preferable that n is 1 because the presence of a plurality of “waves” or “brains” of standing waves in the dielectric layer 124 makes it easier to generate a plurality of modes and makes it difficult to achieve uniformity in the circumferential direction. Further, since the plurality of slots 123 are arranged circumferentially, microwaves can be radiated circumferentially, and the uniformity of plasma in the circumferential direction can be improved.

  The dielectric layer 124 is an air layer. Referring to FIG. 3, the upper surface of the microwave transmitting member 122 is in contact with the dielectric layer 124 on the outer peripheral side of the outer edges of the plurality of slots 123. In the present embodiment, the microwave transmission member 122 is arranged on the outer peripheral side of the outer edges of the plurality of slots 123. Therefore, the dielectric layer 124 is formed between each of the plurality of slots 123 and the microwave transmission member 122 as a transmission path connecting the plurality of slots 123 and the microwave transmission member 122.

  With such a configuration, the microwaves radiated from the plurality of slots 123 become standing waves in the dielectric layer 124, are transmitted to the microwave transparent member 122, and are radiated from the microwave transparent member 122 into the chamber 1.

  In this way, the air layer of the dielectric layer 124 serves as a microwave transmission path and propagates the microwaves to the microwave transmission member 122, so that the microwave transmission member 122 having a large diameter is uniformly distributed in the circumferential direction. And stable plasma can be generated.

  FIG. 8A schematically shows an example of the electric field intensity in the plasma of the microwave radiated into the chamber 1 in the case of the comparative example in which the microwave transmission member 122 is provided directly below the slot 123. The peak of the electric field intensity in the plasma due to the microwaves radiated from the microwave transmitting member 122 is below the inner edge of the microwave transmitting member 122. As a result, the peak of the electric field strength in the plasma is located below the inner edge of the ring-shaped microwave transmission member 122. In the case of the comparative example of FIG. 8A, the peaks of the electric field strength in the plasma overlap at the center of the chamber 1. If there is a portion where the electric field strengths overlap on both sides in this way, the controllability of the electric field strengths deteriorates, which may hinder stable plasma generation.

  On the other hand, the inner edge of the microwave transmission member 122 according to the present embodiment is arranged on the outer peripheral side of the outer edges of the plurality of slots 123, as shown in FIG. 8B. As a result, the microwave transmission member 122 has a larger diameter than the comparative example, and the microwave is radiated from the outer peripheral side as compared with the comparative example. Thereby, the peaks of the electric field strength do not overlap in the central portion of the chamber 1 or the overlapping range can be reduced. This makes it possible to improve the controllability of the electric field strength in the central portion of the chamber 1.

  Further, as shown in FIG. 9A, in the case of the comparative example in which the microwave transmitting member 122 is provided just below the slot 123, a peak of the electric field intensity P1 in the plasma occurs near the edge of the wafer having a diameter of 300 mm. .. On the other hand, in the case of the present embodiment in which the microwave transmitting member 122 is provided on the outer peripheral side of the slot 123, the inner diameter of the microwave transmitting member 122 is 300 mm or more, and the electric field strength in the plasma on the outer peripheral side of the wafer. The peak of P2 occurs. As a result, the electric field strength can be made uniform and flat in the space above the wafer, and plasma can be generated more uniformly.

  The inner diameter of the microwave transmitting member 122 needs to be equal to or longer than a predetermined length according to the wavelength (frequency) of the microwave in terms of design. For example, when the frequency of the microwave is 500 MHz to 3 GHz, the inner diameter of the microwave transmitting member 122 needs to be 300 mm or more in design.

  Further, as shown in FIG. 9B, in the circumferential direction having a diameter of 150 mm from the center of the chamber 1, the electric field strength P2 in the plasma according to the present embodiment is higher than the electric field strength P1 in the plasma according to the comparative example. It has a uniform distribution. As described above, by making the diameter of the microwave transmission member 122 according to the present embodiment larger than the diameter of the wafer, the peak of the electric field strength in the plasma is moved to the outside of the wafer, and the electric field strength distribution in the chamber 1 is reduced. The controllability can be enhanced. As a result, the wafer W can be subjected to uniform plasma processing.

<Operation of plasma processing apparatus>
Next, the operation of the microwave plasma processing apparatus 100 configured as above will be described.

  First, the wafer W is loaded into the chamber 1 and mounted on the mounting table 11. Then, a plasma generating gas such as Ar gas or a gas to be decomposed with high energy is supplied from the first gas supply source 22 as the first gas. The first gas is introduced into the chamber 1 from the first gas introduction part 21 of the microwave radiating member 50.

  The microwaves transmitted from the microwave output unit 30 to the plurality of amplifier units 42 of the microwave transmission unit 40 and the plurality of microwave introduction mechanisms 43a and 43b are radiated into the chamber 1 via the microwave radiation member 50. .. The high electric field energy of the microwave radiated on the surface of the ceiling part turns the first gas into plasma, and surface wave plasma is generated.

  The processing gas to be supplied without being decomposed as much as possible is supplied from the second gas supply source 28 as the second gas. The second gas is introduced into the chamber 1 via the second gas introduction part 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 located away from the surface of the microwave radiating member 50 and has a lower energy, the second gas is excited in a state where unnecessary decomposition is suppressed. Then, the wafer W is subjected to plasma treatment, for example, film formation treatment or etching treatment, by the plasma of the first gas and the second gas.

  At this time, the six peripheral microwave introduction mechanisms 43a are oscillated from the microwave oscillator 32 of the microwave output unit 30, amplified by the amplifier 33, and then distributed by the distributor 34 into a plurality of amplifier units 42. The passed microwave power is supplied. The microwave power supplied to the peripheral microwave introducing mechanism 43a is transmitted through the microwave transmission path 44 and introduced to the peripheral edge of the microwave radiating member 50. At that time, the impedance is automatically matched by the slug 61, and the microwave is introduced in a state where there is substantially no power reflection. The introduced microwaves pass through the slow wave material 121, pass through the slots 123 of the slot antenna section, pass through the dielectric layer 124, and are radiated into the chamber 1 through the microwave transmission member 122. As a result, surface waves are formed on the corresponding portions of the lower surfaces of the microwave transmission member 122 and the main body 120, and the surface waves generate surface wave plasma in the chamber 1 immediately below the microwave radiating member 50.

  At this time, twelve arc-shaped slow wave materials 121 are arranged along the peripheral microwave introducing mechanism arrangement area so as to form a ring shape as a whole. The 12 slow wave materials 121 are separated by a metal portion 120a forming a part of the main body 120, and the peripheral microwave introducing mechanism 43a is arranged so as to straddle between the two slow wave materials 121, respectively. Has been done. That is, the 12 slow-wave members 121 are arranged so as to extend from the positions corresponding to the six peripheral microwave introducing mechanisms 43a to both sides. In this way, the metal portion 120a of the main body 120 is arranged immediately below the peripheral microwave introducing mechanism 43a. Therefore, the microwave transmitted through the peripheral microwave introducing mechanism 43a is separated by the metal portion 120a, and the electric field strength of the portion directly below the peripheral microwave introducing mechanism 43a where the normal microwave electric field becomes large does not increase, and It is equally distributed to the slow wave material 121 on both sides.

  Then, the microwave is radiated from the slot 123 provided along the peripheral microwave introduction mechanism arrangement region so as to have a circular shape as a whole. Since the microwave transmitting member 122 is provided on the outer peripheral side of the slot 123, the microwave power evenly distributed by the slow wave material 121 is uniformly radiated by the slot 123, and the microwave transmitting member 122 having a large diameter. Can be spread in a circle. For this reason, a uniform microwave electric field can be formed immediately below the microwave transmitting member 122 along the peripheral microwave introducing mechanism arrangement region, and a uniform surface wave plasma is formed in the chamber 1 in the circumferential direction, which is stable. Plasma can be generated.

  Since the microwave power can be spread in the circumferential direction in this way, the peripheral microwave introducing mechanism 43a can be reduced from six to three, and the device cost can be reduced.

  In addition, the number of surface acoustic wave modes can be reduced by adjusting the number, shape, and arrangement of the slots 123 arranged in a circumferential shape, and the mode can be reduced by optimizing the number, shape, and arrangement of slots. The number can be two, or even one. By reducing the number of surface wave modes in this way, stable plasma processing with few mode jumps can be performed. Further, by adjusting the number, shape, arrangement, etc. of the slots 123 in this way, the interference of microwaves from one peripheral edge microwave introducing mechanism 43a to the other peripheral edge microwave introducing mechanism 43a is suppressed. be able to.

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

  Further, the microwave is introduced from the central microwave introducing mechanism 43b into the central portion of the microwave radiating member 50. The microwave introduced from the central microwave introducing mechanism 43b passes through the wave retarding material 131, is radiated into the chamber 1 through the slot 133 of the slot antenna section and the microwave transmitting member 132, and is centered in the chamber 1. Surface wave plasma is also generated. Therefore, uniform plasma can be formed in the entire wafer placement region in the chamber 1.

  Further, the microwave radiating member 50 is provided with the first gas introduction part 21, 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. This makes it possible to excite the first gas with high energy and decompose the gas to form surface wave plasma. In addition, by providing the second gas introduction unit 23 at a position lower than the first gas introduction unit 21 and supplying the second gas, the second gas is kept in a state where unnecessary decomposition is suppressed by lower energy. It can be turned into plasma. This makes it possible to form a preferable plasma state according to the required plasma treatment.

(Microwave plasma processing apparatus according to modification 1)
Next, a microwave plasma processing apparatus 100 to which the microwave radiating member 50 described above is applied according to the first modification of the embodiment will be described with reference to FIG. 10. FIG. 10 shows an example of a vertical cross section of the microwave plasma processing apparatus 100 according to Modification 1 of the present embodiment. The microwave plasma processing apparatus 100 according to Modification 1 is different from the microwave plasma processing apparatus 100 shown in FIG. 1 only in the mechanism of the second gas introduction unit 23. Therefore, only the mechanism of the second gas introduction unit 23 according to the first modification will be described here.

  In this modification, the microwave radiating member 50 is provided with the second gas introducing unit 23 having a ring-shaped shower structure. In the second gas introduction part 23, a plurality of nozzles 23a extending below the ceiling part are evenly arranged. A second gas supply source 28 is connected to the second gas introduction unit 23 via a gas supply pipe 112.

From the second gas supply source 28, a processing gas to be supplied without being decomposed as much as possible during plasma processing such as film forming processing and etching processing, for example, a second gas such as SiH ₄ gas or C ₅ F ₈ gas is supplied. It is being supplied. The second gas is supplied from the ring-shaped shower structure via the gas supply pipe 112 to the nozzle 23a extending toward the wafer W side to a position lower than the ceiling of the chamber 1. The 2nd gas introduction part 23 concerning a modification is the 2nd gas shower head which supplies the 2nd gas from a plurality of gas holes with the 2nd height lower than the 1st height which supplies the 1st gas. This is an example.

  By supplying the second gas to a position lower than the first gas introduction part 21 in this way, the second gas can be turned into plasma with lower energy while suppressing unnecessary decomposition. This makes it possible to form a preferable plasma state according to the required plasma treatment.

  Also in the modification 1, the inner edge of the microwave transmitting member 122 is arranged on the outer peripheral side of the outer edges of the plurality of slots 123. As a result, the microwave transmission member 122 has a large diameter, and microwaves are radiated from the outer peripheral side. Thereby, the peaks of the electric field strength do not overlap in the central portion of the chamber 1 or the overlapping range can be reduced. This makes it possible to improve the controllability of the electric field strength in the central portion of the chamber 1. Further, the diameter of the microwave transmission member 122 according to the present embodiment can be made larger than the diameter of the wafer of 300 mm. As a result, uniform plasma can be formed in the entire wafer arrangement area in the chamber 1. As a result, the wafer W can be subjected to uniform plasma processing.

(Microwave plasma processing apparatus according to modification 2)
Next, a microwave plasma processing apparatus 100 according to Modification 2 of the embodiment will be described with reference to FIG. 11. FIG. 11 shows an example of a vertical cross section of a microwave plasma processing apparatus 100 according to Modification 2 of the present embodiment.

  In the microwave plasma processing apparatus 100 of Modification 2, the central microwave introducing mechanism 43b is not provided, but the annular microwave radiating member 50 including the arrangement area of the peripheral microwave introducing mechanism 43a is provided. A conductive shower head 150 having a size substantially equal to that of the wafer W is provided in the central portion inside thereof through an insulating member 151.

  The shower head 150 has a disk-shaped gas diffusion space 152, a large 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 supply 156 for plasma generation 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. Gas necessary for plasma processing is supplied from the gas supply source 157 into the chamber 1 through the gas supply pipe 158 and the shower head 150. By supplying high frequency power to the shower head 150 from the high frequency power supply 156, a high frequency electric field is formed between the shower head 150 and the mounting table 11, and capacitively coupled plasma is formed in the space immediately above the wafer W.

  In the microwave plasma processing apparatus 100 having such a configuration, the configuration of the central portion is similar to that of a parallel plate type plasma etching apparatus that performs plasma etching on the wafer W. Therefore, for example, it can be used as a plasma etching apparatus that adjusts the plasma density of the periphery of the wafer with surface wave plasma using microwaves. It is also possible not to provide a mechanism for generating plasma in the central portion.

  Also in the second modification, the inner edge of the microwave transmission member 122 is arranged on the outer peripheral side of the outer edges of the plurality of slots 123. As a result, the microwave transmission member 122 has a large diameter, and microwaves are radiated from the outer peripheral side. As a result, the peaks of the electric field strength do not overlap in the central portion of the chamber 1 or the overlapping range can be reduced. As a result, the controllability of the electric field strength can be improved in the central portion of the chamber 1. Further, the diameter of the microwave transmission member 122 according to the present embodiment can be made larger than the diameter of the wafer of 300 mm. As a result, uniform plasma can be formed in the entire wafer placement area in the chamber 1. As a result, the wafer W can be subjected to uniform plasma processing.

  As described above, according to the microwave plasma processing apparatus 100 according to the present embodiment and Modifications 1 and 2, the inner edge of the microwave transparent member 122 is arranged on the outer peripheral side of the outer edges of the plurality of slots 123. It The dielectric layer 124 that connects the plurality of slots 123 and the microwave transmission member 122 functions as a transmission path that transmits microwaves. As a result, the controllability of the electric field intensity distribution in the chamber 1 can be improved, and uniform and stable plasma can be generated in the circumferential direction.

  Although the microwave plasma processing apparatus has been described above with the above-described embodiment, the microwave plasma processing apparatus according to the present invention is not limited to the above-described embodiment and Modifications 1 and 2, and various modifications are possible within the scope of the present invention. Can be modified and improved. The matters described in the above-described embodiment and the modified examples 1 and 2 can be combined within a range that does not contradict.

  For example, in the above-described embodiment and Modifications 1 and 2, the configurations of the microwave output unit 30 and the microwave transmission unit 40 are not limited to the above-described embodiment, and for example, the microwave radiated from the slot antenna unit is used. If it is not necessary to control the directivity of the wave or make it circularly polarized, the phase shifter is not necessary.

  Furthermore, in the above-described embodiment, an example in which a plurality of microwave introduction mechanisms are used when introducing the microwave plasma source 2 into the microwave radiating member 50 has been described. However, according to the present invention, it is sufficient that a single surface wave mode can be obtained when microwaves are radiated from the slots arranged circumferentially and a surface wave plasma is generated. It may be provided and the introduction mode of the microwave is not limited. It is also possible not to provide a mechanism for generating plasma in the central portion.

  Further, in the above-described embodiment, the film forming apparatus and the etching apparatus are illustrated as the plasma processing apparatus, but the present invention is not limited to this, and the oxynitride film forming processing including the oxidation processing and the nitriding processing, other plasma processing such as ashing processing, etc. Can also be used.

  The substrate is not limited to the wafer W, and may be another substrate such as an FPD (flat panel display) substrate typified by a substrate for LCD (liquid crystal display) or a ceramic substrate.

DESCRIPTION OF SYMBOLS 1 chamber 2 microwave plasma source 3 control device 11 mounting table 21 first gas introduction part 22 first gas supply source 23 second gas introduction part 28 second gas supply source 30 microwave output part 40 microwave transmission part 43a peripheral microwave Wave introducing mechanism 43b Central microwave introducing mechanism 44 Microwave transmission line 50 Microwave radiating member 52 Outer conductor 53 Inner conductor 61 Slug 100 Microwave plasma processing apparatus 120 Main body 121 Slow wave material 122 Microwave transmitting member 123 Slot 124 Dielectric Layer 140 Impedance adjusting member

Claims (6)

A microwave plasma processing apparatus having a chamber for housing a substrate and a microwave radiating member for radiating a microwave in the chamber, wherein the substrate is plasma-treated by surface wave plasma.
The microwave radiating member,
A metal body,
A dielectric slow-wave member that is formed on the side of the main body where microwaves are introduced and that transmits microwaves,
A plurality of slots that are formed on the lower surface of the slow-wave material and radiate microwaves that have propagated through the slow-wave material,
A ring-shaped exposed microwave surface of the chamber in the main body, a microwave transmitting member made of a dielectric for transmitting microwaves into the chamber,
A dielectric layer provided between the plurality of slots and the microwave transmitting member, for propagating the microwaves radiated from the plurality of slots to the microwave transmitting member,
The inner edge of the microwave transmitting member is arranged on the outer peripheral side of the outer edges of the plurality of slots,
Microwave plasma processing equipment. The dielectric layer is an air layer,
The microwave plasma processing apparatus according to claim 1. The upper surface of the microwave transmitting member is in contact with the dielectric layer on the outer peripheral side of the outer edges of the plurality of slots,
The microwave plasma processing apparatus according to claim 1. When the effective wavelength of the microwave of the dielectric layer is λ, the dielectric layer has a length of (λ/2)×n (n≧1) in the circumferential direction.
The microwave plasma processing apparatus according to claim 1. The inner diameter of the microwave transmitting member is larger than the diameter of the substrate,
The microwave plasma processing apparatus according to claim 1. A gas supply mechanism for supplying gas from the gas shower head into the chamber,
The gas shower head is
A first gas showerhead for supplying a first gas at a first height from a plurality of gas holes formed in the microwave radiating member;
A second gas showerhead having a plurality of nozzles and supplying a second gas from the plurality of nozzles at a second height lower than a first height at which the first gas is supplied;
The microwave plasma processing apparatus according to claim 1.

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