JP2018101587A - Microwave plasma processing device and microwave introduction mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the radiant quantity of electromagnetic waves which contributes to plasma processing.SOLUTION: Provided is a microwave plasma processing device operable to produce plasma of a gas by microwaves to perform a plasma process in a process chamber. The microwave plasma processing device comprises three or more microwave introduction mechanisms in a ceiling portion of the process chamber. Each microwave introduction mechanism has: a dielectric wave-delay material which allows microwaves to transmit therethrough; an antenna of a conductive member having a slot in a lower face of the wave-delay material; and a dielectric microwave transmission window for introducing microwaves having passed through the slot into the process chamber. In the case of the microwave introduction mechanism provided on an outer edge with respect to a center portion of the process chamber, the slot of the antenna is in a circular arc form, and has an opened portion where the slot partially opens toward the center portion at a predetermined angle.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a microwave plasma processing apparatus and a microwave introduction mechanism.

  Compared with a parallel plate type plasma processing apparatus, the microwave plasma processing apparatus can form surface wave plasma with high density and low electron temperature. In the microwave plasma processing apparatus, microwaves are radiated from the ceiling of the chamber into the chamber through a plurality of microwave introduction mechanisms (see, for example, Patent Document 1). In Patent Document 1, a microwave transmission window made of a dielectric is provided for each microwave introduction mechanism provided on the ceiling of the chamber, and microwaves are radiated into the chamber through the microwave transmission window. Surface wave plasma is generated at the ceiling portion on the chamber side by the radiated microwave, and the substrate is subjected to plasma processing by the surface wave plasma.

JP 2012-216745 A

  However, if a microwave introduction mechanism is provided on the outer peripheral side of the central part of the ceiling part on the chamber side, a part of the radiated microwave is consumed by plasma in the chamber wall or in the vicinity of the chamber wall, and the wafer It does not contribute to plasma processing such as film formation or etching.

  In one aspect, the present invention is directed to increasing the radiation amount of electromagnetic waves that contribute to plasma processing.

  In order to solve the above-described problem, according to one aspect, a microwave plasma processing apparatus that converts a gas into a plasma by microwaves and performs plasma processing in the processing container, wherein three are provided on the ceiling of the processing container. The microwave introduction mechanism includes the dielectric slow wave material that transmits microwaves, the conductive member antenna having a slot on the lower surface of the slow wave material, and the slot. When the microwave introduction mechanism is provided at an outer edge than the central portion of the processing container, the slot of the antenna is There is provided a microwave plasma processing apparatus that has an arc shape and has an opening that opens at a predetermined angle toward a central portion of the slot.

  According to one aspect, it is possible to increase the radiation amount of electromagnetic waves that contribute to plasma processing.

The figure which shows an example of the longitudinal cross-section of the microwave plasma processing apparatus which concerns on one Embodiment. The figure which shows an example of a structure of the control part which concerns on one Embodiment. The enlarged view which shows an example of the microwave introduction apparatus which concerns on one Embodiment. The figure which shows an example of the microwave introduction mechanism of the center part shown in FIG. The perspective view which shows an example of the antenna of the microwave introduction mechanism shown in FIG. The figure which shows an example of the shape of the slot of the antenna shown in FIG. The figure which shows an example of the microwave introduction mechanism of the outer peripheral part shown in FIG. The perspective view which shows an example of the antenna of the microwave introduction mechanism shown in FIG. The figure which shows an example of the slot shape of the antenna shown in FIG. The figure which shows an example of the bottom face of the ceiling part of the processing container shown in FIG. The figure which shows an example of the result of the electric field simulation when changing the shape of the slot which concerns on one Embodiment. The figure which shows an example of the bottom face of the ceiling part of the processing container shown in FIG. The figure which shows an example of the result of the electric field simulation when changing the opening and diameter of the slot which concern on one Embodiment. The figure which shows an example of the result of the electric field simulation when changing the shape, opening, and diameter of the slot which concerns on one Embodiment. The figure which shows an example of the result of the electric field simulation when changing the shape, opening, and diameter of the slot which concerns on 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.
[Microwave plasma processing equipment]
Hereinafter, an example of a microwave plasma processing apparatus 1 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 shows an example of a longitudinal section of a microwave plasma processing apparatus 1 according to an embodiment. FIG. 2 shows an example of the configuration of the control unit 8 shown in FIG. The microwave plasma processing apparatus 1 according to the present embodiment performs predetermined plasma processing such as film formation processing, diffusion processing, etching processing, and ashing processing on a semiconductor wafer (hereinafter referred to as “wafer”) W, for example. Device.

  The microwave plasma processing apparatus 1 includes a processing container 2 that houses a wafer W that is an example of a substrate. Inside the processing container 2, a mounting table 21 for mounting the wafer W on the mounting surface 21a is disposed. The microwave plasma processing apparatus 1 also includes a gas supply mechanism 3 that supplies a gas into the processing container 2 and an exhaust device 4 that exhausts the processing container 2 under reduced pressure. Further, the microwave plasma processing apparatus 1 generates a microwave for generating plasma in the processing container 2 and introduces a microwave into the processing container 2 and the microwave plasma processing apparatus 1. The control part 8 which controls each structure part of FIG.

  The processing container 2 has a substantially cylindrical shape, for example, and is formed of a metal material such as aluminum and an alloy thereof. The processing container 2 is formed of a conductive member, and includes a plate-like ceiling portion 11, a bottom portion 13, and a side wall portion 12 that connects the ceiling portion 11 and the bottom portion 13. The ceiling part 11 has seven openings. The ceiling portion 11 is provided with seven microwave introduction mechanisms 63 for closing the seven openings, and microwaves (electromagnetic waves) are introduced into the processing container 2 to generate plasma in the processing container 2. In the present embodiment, seven microwave introduction mechanisms 63 are disposed in the seven openings of the ceiling portion 11. However, the number of openings may be three or more, and the same number of microwave introduction mechanisms as the number of openings. 63 is disposed on the ceiling 11.

  The side wall portion 12 has a loading / unloading port 12a for loading / unloading the wafer W. The loading / unloading port 12a is opened and closed by a gate valve G. The gate valve G hermetically seals the processing container 2 in the closed state, and loads and unloads the wafer W from the processing container 2 in the open state.

  The bottom 13 has a plurality of exhaust ports 13a. The plurality of exhaust ports 13 a are respectively connected to the plurality of exhaust devices 4 through the exhaust pipe 14. The exhaust device 4 includes an APC valve and a high-speed vacuum pump that can depressurize the internal space of the processing vessel 2 at a high speed to a predetermined degree of vacuum. Examples of such a high-speed vacuum pump include a turbo molecular pump. By operating the high-speed vacuum pump of the exhaust device 4, the internal space of the processing container 2 is depressurized to a predetermined degree of vacuum, for example, 0.133 Pa.

  The microwave plasma processing apparatus 1 includes a support member 22 that supports the mounting table 21 in the processing container 2, and an insulating member 23 provided between the support member 22 and the bottom portion 13 of the processing container 2. The mounting table 21 mounts the wafer W horizontally. The mounting table 21 and the support member 22 are made of, for example, aluminum whose surface is anodized (anodized).

  The microwave plasma processing apparatus 1 includes a high frequency power supply 25 that supplies high frequency power to the mounting table 21, and a matching unit 24 provided between the mounting table 21 and the high frequency power supply 25. The high frequency power supply 25 supplies high frequency power to the mounting table 21 in order to draw ions into the wafer W.

  The microwave plasma processing apparatus 1 may have a temperature control mechanism. For example, the temperature control mechanism controls the temperature of the wafer W within a range of 25 ° C. (room temperature) to 900 ° C. The microwave plasma processing apparatus 1 further includes a gas introduction part 15 provided in the ceiling part 11 of the processing container 2. The gas introduction part 15 has a plurality of nozzles 16 having a cylindrical shape. A gas hole 16 a is formed on the lower surface of the nozzle 16.

  The gas supply mechanism 3 includes a gas supply source 31 and a pipe 32 that connects the gas supply source 31 and the gas introduction unit 15. In addition, the gas supply source 31 may be one or plural. The gas supply source 31 supplies, for example, a rare gas for plasma generation or a gas used for oxidation treatment, nitridation treatment, film formation treatment, etching treatment, and ashing treatment. The flow rate of the gas supplied from the gas supply source 31 is controlled by a mass flow controller and an open / close valve.

  Each component of the microwave plasma processing apparatus 1 is connected to the control unit 8 and controlled by the control unit 8. As shown in FIG. 2, the control unit 8 includes a process controller 81 having a CPU, a user interface 82 connected to the process controller 81, and a storage unit 83.

  In the microwave plasma processing apparatus 1, the process controller 81 is a control unit that controls each component related to process conditions such as temperature, pressure, gas flow rate, high-frequency power for bias application, microwave output, and the like. is there. Examples of each component include a high-frequency power source 25, a gas supply source 31, an exhaust device 4, a microwave introduction device 5, and the like.

  The user interface 82 includes a keyboard and a touch panel on which an administrator inputs commands to manage the microwave plasma processing apparatus 1, a display that visualizes and displays the operating status of the microwave plasma processing apparatus 1, and the like.

  The storage unit 83 stores a control program (software) for realizing various processes executed by the microwave plasma processing apparatus 1 under the control of the process controller 81, a recipe in which processing condition data, and the like are recorded. ing. The process controller 81 calls and executes an arbitrary control program or recipe from the storage unit 83. Further, the process controller 81 performs processing in accordance with an instruction from the user interface 82. Thereby, desired processing is performed in the processing container 2 of the microwave plasma processing apparatus 1 under the control of the process controller 81.

As the control program and the recipe, for example, a program stored in a computer-readable storage medium such as a CD-ROM, a hard disk, a flexible disk, a flash memory, a DVD, or a Blu-ray disk can be used. Also, the above recipe can be transmitted from other devices as needed via, for example, a dedicated line and used online.
[Microwave introduction mechanism]
Next, the microwave introduction mechanism 63 will be described. FIG. 3 is an explanatory diagram showing an example of the configuration of the microwave introduction mechanism 63 common to the microwave introduction mechanism 63 in the central portion and the microwave introduction mechanism 63 in the outer peripheral portion.

  FIG. 4 is a cross-sectional view showing the microwave introduction mechanism 63 at the center. FIG. 7 is a cross-sectional view showing the microwave introduction mechanism 63 in the outer peripheral portion. FIG. 5 is a perspective view showing an antenna of the microwave introduction mechanism 63 shown in FIG. FIG. 6 shows an example of the shape of the slot of the antenna shown in FIG. FIG. 8 is a perspective view showing an antenna of the microwave introduction mechanism 63 shown in FIG. FIG. 9 shows an example of the shape of the slot of the antenna shown in FIG.

  As shown in FIGS. 1 and 3, the microwave introduction device 5 includes a microwave output unit 50 that distributes and outputs a microwave to a plurality of paths, and a microwave that is output from the microwave output unit 50. 2 has an antenna unit 60 to be introduced. The surface wave of the microwave introduced from the microwave introduction device 5 propagates to the ceiling portion 11 of the processing container 2.

  As shown in FIG. 3, the microwave output unit 50 includes a power supply unit 51, a microwave oscillator 52, an amplifier 53 that amplifies the microwave oscillated by the microwave oscillator 52, and a microwave amplified by the amplifier 53. And a distributor 54 that distributes the image to a plurality of paths. The microwave oscillator 52 oscillates microwaves (for example, PLL oscillation) at a predetermined frequency. The predetermined frequency may be, for example, 2.45 GHz, 8.35 GHz, 5.8 GHz, 1.98 GHz, or the like. Such a microwave output unit 50 can also be applied to a case where the frequency of the microwave is in the range of 800 MHz to 1 GHz. The distributor 54 distributes the microwave while matching the impedances of the input side and the output side.

  As shown in FIGS. 1 and 3, the antenna unit 60 includes a plurality of antenna modules 61. Each of the plurality of antenna modules 61 introduces the microwave distributed by the distributor 54 into the processing container 2. In the present embodiment, as shown in FIG. 3, the configurations of the plurality of antenna modules 61 are all the same. Each antenna module 61 includes an amplifier unit 62 that mainly amplifies and outputs the distributed microwave, and a microwave introduction mechanism 63 that introduces the microwave output from the amplifier unit 62 into the processing container 2. The microwave introduction mechanism 63 is a general term for the seven microwave introduction mechanisms 63a to 63g. FIG. 1 shows three microwave introduction mechanisms 63a, 63b, and 63e.

  The amplifier unit 62 includes a phase shifter 62A that changes the phase of the microwave, a variable gain amplifier 62B that adjusts the power level of the microwave that is input to the main amplifier 62C, and a main amplifier 62C that is configured as a solid-state amplifier. Contains. The amplifier unit 62 includes an isolator 62D that separates reflected microwaves reflected by the antenna of the microwave introduction mechanism 63 and directed toward the main amplifier 62C.

  The phase shifter 62A is configured to change the microwave radiation characteristic by changing the phase of the microwave. The phase shifter 62A is used to change the plasma distribution by controlling the directivity of the microwave by adjusting the phase of the microwave for each antenna module 61, for example. If such adjustment of the radiation characteristics is not performed, the phase shifter 62A may not be provided.

  The variable gain amplifier 62B is used for adjusting variations of individual antenna modules 61 and adjusting plasma intensity. For example, by changing the variable gain amplifier 62B for each antenna module 61, the plasma distribution in the entire processing container 2 can be adjusted.

  The main amplifier 62C includes, for example, an input matching circuit, a semiconductor amplifying element, an output matching circuit, and a high Q resonance circuit. As the semiconductor amplifying element, for example, GaAs HEMT, GaN HEMT, and LD (Laterally Diffused) -MOS capable of class E operation are used.

The isolator 62D has a circulator and a dummy load (coaxial terminator). The circulator guides the reflected microwave reflected by the antenna of the microwave introduction mechanism 63 to the dummy load. The dummy load converts the reflected microwave guided by the circulator into heat. In the present embodiment, a plurality of antenna modules 61 are provided, and the plurality of microwaves introduced into the processing container 2 by the microwave introduction mechanisms 63 of the plurality of antenna modules 61 are stored in the processing container 2. Is synthesized. Therefore, each isolator 62D may be small, and the isolator 62D can be provided adjacent to the main amplifier 62C.
(Microwave introduction mechanism in the center)
The description will be further continued with reference to FIG. 4 showing an enlarged view of the microwave introduction mechanism 63a disposed at the center of the processing vessel 2 among the plurality of microwave introduction mechanisms 63 of FIG. The microwave introduction mechanism 63 a includes a tuner 64 that matches impedance, and an antenna 65 that radiates the amplified microwave into the processing container 2. The microwave introduction mechanism 63a is made of a metal material and has an outer conductor 66 having a cylindrical shape extending in the vertical direction in FIG. 4 and an inner conductor extending in the same direction as the direction in which the outer conductor 66 extends in the outer conductor 66. 67. The inner conductor 67 has a rod shape or a cylindrical shape. The outer conductor 66 and the inner conductor 67 constitute a coaxial tube. A space between the inner peripheral surface of the outer conductor 66 and the outer peripheral surface of the inner conductor 67 forms a microwave transmission path 68.

  The antenna module 61 includes a feed conversion unit provided on the base end side (upper end side) of the outer conductor 66. The power feeding conversion unit is connected to the main amplifier 62C via a coaxial cable. The isolator 62D is provided in the middle of the coaxial cable.

  The antenna 65 is provided on the opposite side of the outer conductor 66 from the feed conversion unit. A portion of the outer conductor 66 closer to the base end than the antenna 65 is an impedance adjustment range by the tuner 64. 4 and 5, the antenna 65 includes a planar antenna 71a connected to the lower end of the inner conductor 67, a microwave slow wave material 72 disposed on the upper surface side of the planar antenna 71a, and a planar antenna. And a microwave transmission plate 73A disposed on the lower surface side of 71a. The lower surface of the microwave transmission plate 73 </ b> A is exposed in the internal space of the processing container 2. The microwave transmission plate 73 </ b> A is fitted into the opening of the ceiling portion 11, which is a conductive member of the microwave introduction device 5, via the outer conductor 66.

  The planar antenna 71a has a disk shape and has a slot Sa penetrating through the inside. In the example shown in FIGS. 5 and 6, four slots Sa are provided in a circumferential shape, and each slot Sa has an arc shape that is equally divided into four. The number of slots Sa is not limited to four, but may be five or more, or may be one or more and three or less. The inside of the slot Sa may be filled with a dielectric such as alumina or quartz, or may be a space.

  The microwave slow wave material 72 is made of a material having a dielectric constant larger than that of vacuum. As a material for forming the microwave slow wave material 72, for example, fluororesin such as quartz, ceramics, polytetrafluoroethylene resin, polyimide resin, or the like can be used. Microwaves have a longer wavelength in vacuum. The microwave slow wave material 72 has a function of adjusting the plasma by shortening the wavelength of the microwave.

  The microwave transmission plate 73A is made of a dielectric material. As a dielectric material for forming the microwave transmitting plate 73A, for example, quartz or ceramics is used. The microwave transmission plate 73A has a shape capable of efficiently radiating microwaves in the TE mode. In the example shown in FIG. 5, the microwave transmission plate 73A has a rectangular parallelepiped shape. The microwave transmitting plate 73A may have a cylindrical shape.

  In the microwave introduction mechanism 63a having such a configuration, the microwave amplified by the main amplifier 62C passes between the inner peripheral surface of the outer conductor 66 and the outer peripheral surface of the inner conductor 67 (microwave transmission path 68) and is a planar antenna. 71a is reached. Then, the microwave passes through the slot Sa of the planar antenna 71a, passes through the microwave transmission plate 73A, and is radiated to the internal space of the processing container 2.

  The tuner 64 constitutes a slag tuner. Specifically, as shown in FIG. 4, the tuner 64 has two slugs 74 </ b> A and 74 </ b> B disposed on the base end side (upper end side) of the outer conductor 66 than the antenna 65. The tuner 64 includes an actuator 75 that operates the two slugs 74 </ b> A and 74 </ b> B, and a tuner controller 76 that controls the actuator 75.

  The slugs 74 </ b> A and 74 </ b> B have a plate shape and an annular shape, and are disposed between the inner peripheral surface of the outer conductor 66 and the outer peripheral surface of the inner conductor 67. The slugs 74A and 74B are made of a dielectric material. As a dielectric material for forming the slags 74A and 74B, for example, high-purity alumina having a relative dielectric constant of 10 can be used. High-purity alumina usually has a relative dielectric constant larger than that of quartz (relative dielectric constant 3.88) or Teflon (registered trademark) (relative dielectric constant 2.03), which is used as a material for forming slag. The thickness of 74A, 74B can be made small. In addition, high-purity alumina has a lower dielectric loss tangent (tan δ) than quartz or Teflon (registered trademark), and can reduce microwave loss.

  The tuner 64 moves the slugs 74 </ b> A and 74 </ b> B in the vertical direction by the actuator 75 based on a command from the tuner controller 76. Thereby, the tuner 64 adjusts the impedance.

(Microwave introduction mechanism on the outer periphery)
Next, the microwave introduction mechanisms 63b to 63g in the outer periphery will be described in detail. The microwave introduction mechanisms 63b to 63g in the outer peripheral portion are evenly arranged in the circumferential direction and have the same structure. Here, the microwave introduction mechanism 63b will be described as an example. FIG. 7 is an explanatory diagram showing an example of the configuration of the microwave introduction mechanism 63b in the outer peripheral portion. FIG. 8 is a perspective view showing the microwave introduction mechanism 63b in the outer peripheral portion shown in FIG. FIG. 9 shows an example of the slot shape of the antenna shown in FIG.

  In the present embodiment, the seven microwave introduction mechanisms 63b to 63g are provided on the outer peripheral portion. However, the number of the microwave introduction mechanisms on the outer peripheral portion is any number of 3 to 10, and they are equally arranged. That's fine.

  The microwave introduction mechanism 63b in the outer peripheral portion is different from the microwave introduction mechanism 63a in the central portion in which the slot Sa of the planar antenna 71a has four arc shapes in that the shape of the slot Sb of the planar antenna 71b is one arc shape. .

That is, the slots Sb to Sf of the microwave introduction mechanisms 63b to 63g in the outer peripheral portion have an arc shape and open at a predetermined angle toward the central portion of the processing container 2 at one place. Hereinafter, the opening portion of the slot is referred to as “opening portion”. There is only one opening in each slot of the microwave introduction mechanisms 63b to 63g on the outer peripheral portion, and the angle is preferably about 60 °, but may be any angle within the range of 30 ° to 90 °.
[Microwave transmission plate]
Next, with reference to FIG. 10, the microwave transmission plates 73A to 73G exposed on the bottom surface of the ceiling portion 11 of the processing container 2 shown in FIG. 1 will be described. FIG. 10 shows an example of the inner side of the ceiling portion 11 of the processing container 2 shown in FIG. The microwave transmission plate 73 is a general term for the microwave transmission plates 73A to 73G.

  The microwave introduction device 5 includes a microwave transmission plate 73A at the center and microwave transmission plates 73B to 73G at the outer periphery. The microwave transmission plates 73A to 73G are examples of microwave transmission windows. The microwave transmission plates 73 </ b> A to 73 </ b> G are exposed to the ceiling surface facing the mounting surface 21 a of the mounting table 21 in a state where the microwave transmitting plates 73 </ b> A to 73 </ b> G are fitted in the plurality of openings of the ceiling portion 11 that is a conductive member of the microwave introduction device 5. To do. Further, the microwave transmission plates 73A to 73G are arranged so that the distances between the center points of the adjacent microwave transmission plates 73 are equal to or substantially equal to each other.

  In this embodiment, in all the microwave transmission plates 73, the distances between the center points of arbitrary three microwave transmission plates 73 adjacent to each other are equal to or substantially equal to each other.

In addition, the gas holes 16a are arranged substantially evenly in the circumferential direction between the microwave transmitting plate 73A in the central portion and the microwave transmitting plates 73B to 73G in the outer peripheral portion.
[Slot shape]
In the microwave plasma processing apparatus 1, the microwave is radiated from the ceiling portion 11 of the processing container 2 into the chamber via the microwave introduction apparatus 5. Microwave transmission plates 73A to 73G (microwave transmission windows) made of dielectric materials of the microwave introduction mechanisms 63a to 63g are provided on the ceiling portion 11 of the processing container 2, and the inside of the processing container 2 is interposed through the microwave transmission windows. A microwave is emitted.

  In particular, when microwaves radiated from the microwave introduction mechanisms 63 b to 63 g in the outer peripheral portion are radiated to the wall side of the processing container 2, they are consumed by plasma in the wall of the processing container 2 or in the vicinity of the wall of the processing container 2. Does not contribute to plasma treatment.

In addition, abnormal discharge may occur in the wall of the processing container 2 due to the propagation of the surface wave of the microwave radiated to the wall of the processing container 2 through the wall of the processing container 2 or the like. For example, the wall of the processing vessel 2 is coated by a thermal spraying of a dielectric such as alumina (Al ₂ O ₃ ), but there are portions that cannot be coated due to the structure. Since the impedance changes at the boundary portion of the presence or absence of coating by thermal spraying, the electric field strength increases at this boundary portion, multi-pactor discharge occurs, and abnormal discharge may occur in some cases. On the other hand, it is conceivable to prevent discharge from occurring at the wall of the processing container 2 by changing the material of the processing container 2, but considering the resistance to plasma and the like, the material of the processing container 2 can be easily changed. Changing is not realistic.

  In the present embodiment, the shape of the slot Sa provided in the microwave introduction mechanism 63a in the central portion is different from the shape of the slots Sb to Sg provided in the microwave introduction mechanisms 63b to 63g in the outer peripheral portion. Increase the amount of electromagnetic wave radiation that contributes to plasma treatment. Thereby, while being able to perform a plasma process efficiently, abnormal discharge can be suppressed by reducing the radiation amount of the microwave radiated | emitted to the wall side of the processing container 2. FIG.

  In particular, in this embodiment, the shape of the slot Sa provided in the microwave introduction mechanism 63a in the central portion is not changed, and the slots Sb to Sg provided in the microwave introduction mechanisms 63b to 63g in the outer peripheral portion (collectively, The shape of “slot S” is also optimized.

  FIG. 11 is an example of a result of calculation by simulation of the state of the electromagnetic field at the bottom of the ceiling 11 using four shapes as the slots S formed in the planar antenna 71 of the microwave introduction mechanism 63. The planar antenna 71 is a general term for the planar antennas 71a to 71g.

  In the simulation, as shown in the lower left of FIG. 11, for the sake of convenience, a microwave of 400 W is supplied to the microwave introduction mechanism 63 in the central portion, and the microwave is not supplied to the microwave introduction mechanism 63 in the outer peripheral portion. It was. For convenience, the simulation was performed by changing the shape of the slot S of the microwave introduction mechanism 63 in the center to the shape of the slot Sa.

  First, in the case of the leftmost triangular slot S in FIG. 11, it is understood from the result of the electric field strength distribution on the ceiling surface in the processing container 2 of the ceiling portion 11 that directivity cannot be obtained in the electric field strength distribution. . Next, in the case of the slot S that is the second annular shape from the left in FIG. 11 and has a cut in part, the distribution of the electric field intensity is close to a concentric circle on the ceiling surface and is almost directional. You can see that there is no. Similarly, in the case of the semicircular arc-shaped slot S having the third opening of 180 ° or more from the left in FIG. 11, the distribution of the electric field intensity on the ceiling surface has a little directivity, but the opening side and its slot It can be seen that there is a bias in plasma density on the opposite side.

  On the other hand, in the case of the arc-shaped slot S having the rightmost opening of about 60 ° in FIG. 11, the electric field strength on the opening side of the slot S is increased, and the electric field strength distribution is distributed over the entire ceiling surface. There is directivity.

  According to this, in the case of the arc-shaped slot S shown in the rightmost part of FIG. 11, the radiation amount of the electromagnetic wave contributing to the plasma processing can be increased by making use of the directivity of the electric field intensity distribution.

  Normally, the electric field strength is highest at the center of the slot S, but in the simulation results, the electric field strength on the side without the slot S (opening side) is higher than the electric field strength on the side with the slot S. The reason is that since the ceiling portion 11 of the processing container 2 is formed of a conductive member, the microwave passing through the slot S is reflected by the ceiling portion 11, so that the intensity of the electromagnetic wave on the side opposite to the slot S is high. This is because it becomes higher.

  The rightmost slot S has a notch S1 on the opposite side of the opening. When the cutout portion S1 is provided, the electric field strength at the center of the slot S is lower than when the cutout portion S1 is not provided. Thereby, it is possible to prevent the electric field intensity on the opening side opposite to the center of the slot S from being excessively increased. Thereby, the directivity becomes a more preferable level, the plasma density becomes uniform, and the uniformity of plasma processing is achieved.

In the present embodiment, the slot width of the notch S1 is about 25% of the width of the other slots. If the notch S1 completely divides the slot, the electric field strength becomes high at the line connecting the opposing openings, and the directivity of the desired electric field strength cannot be obtained.
[Slot Arrangement]
From the above results, an example in which the arc-shaped slot S shown in the rightmost part of FIG. 11 is formed in the planar antenna 71 of the microwave introduction mechanism 63 in the outer peripheral portion will be described with reference to FIG. FIG. 12A shows the microwave plasma processing apparatus 1 shown in FIG. 1, in which the planar antenna 71a of the microwave introduction mechanism 63 at the center has the four arc-shaped slots Sa described above. Therefore, the microwave which permeate | transmits the microwave permeation | transmission board 73A (microwave permeation | transmission window) does not have the directivity of electric field strength.

  On the other hand, the microwave introduction mechanism 63 in the outer peripheral portion has one arc-shaped slot Sb to Sg having an opening portion with a predetermined angle of around 60 °.

  In particular, the openings of the slots Sb to Sg are open toward the center of the processing container 2. That is, in the slots Sb to Sg, radial lines passing from the center point O of the ceiling portion 11 of the processing container 2 to the centers of the microwave transmission plates 73B to 73G of the microwave introduction mechanisms 63 pass through the centers of the openings. The planar antennas 71b to 71g are arranged so that each opening opens toward the center point O. Thereby, the electric field strength on the opening side of the slots Sb to Sg is increased. That is, the microwave radiated from the microwave introduction mechanism 63 on the outer peripheral portion is easily radiated to the center side of the processing container 2 and is not easily radiated to the wall side of the processing container 2. As a result, it is possible to make it difficult for the microwave to be consumed by plasma in the wall of the processing container 2 or in the vicinity of the wall of the processing container 2. In this way, by optimizing the shape and arrangement of the slots, it is possible to increase the amount of microwave radiation that contributes to the plasma processing by utilizing the directivity of the electric field strength.

  The slot shape and arrangement of the microwave introduction mechanisms 63b to 63g in the outer peripheral portion of FIG. 12B are the same as those of the microwave introduction mechanisms 63b to 63g in the outer peripheral portion of FIG. A difference from the case of FIG. 12A is that the microwave introduction mechanism 63a at the center is not provided in FIG. However, also in the microwave introduction mechanism 63 shown in FIG. 12B, the microwave radiated from the microwave introduction mechanism 63 in the outer peripheral portion is easily radiated to the center side of the processing container 2. Therefore, even when the microwave introduction mechanism 63 is arranged as shown in FIG. 12B, the amount of microwave radiation that contributes to plasma processing can be increased.

As shown in FIG. 12C, three microwave introduction mechanisms 63a at the center may be provided. Also in this case, four arc-shaped slots Sa are arranged in the three microwave introduction mechanisms 63a in the central portion, and arcs that open toward the center point O in the microwave introduction mechanisms 63b to 63g in the outer peripheral portion. Shaped slots Sb to Sg are arranged. Even with such a configuration, the microwave radiated from the microwave introduction mechanism 63 in the outer peripheral portion is easily radiated to the center side of the processing container 2, and the amount of microwave radiation contributing to the plasma processing can be increased.
[Slot radius and opening angle]
Next, a simulation was performed to optimize the slot radius and opening angle. The simulation result will be described with reference to FIG. As shown in the upper left frame of FIG. 13, the angle of the opening of the slot S is θ, and the angle θ is changed by ± α ° with respect to 60 °. Specifically, on the horizontal axis of FIG. 13, the angle θ of the opening of the slot S is 30 ° (α = −30 °), 60 ° (α = 0 °), 90 ° with respect to 60 °. An example of the simulation result of the electric field strength when changing (α = 30 °) and 120 ° (α = 60 °) is shown.

  Further, as shown on the vertical axis of FIG. 13, the radius R on the inner peripheral side of the slot S is set to 7 mm (r = -5 mm), 12 mm (r = 0 mm), 17 mm (r = 5 mm) with R = 12 mm as a reference. ), And 22 mm (r = 10 mm), an example of the simulation result of the electric field strength when changed.

  As a result, as shown in the upper left frame of FIG. 13, (1) the circumferential length of the arc-shaped slot S is the same as or close to 1/2 of the wavelength λg of the microwave propagating in the slot S. (2) If the angle of the opening of the slot is in the range of 30 ° to 120 °, the directivity of the desired electric field strength can be obtained, as shown in the horizontal axis of FIG. I understand. That is, since the microwaves are spread from the slot S at an angle of 30 ° to 120 ° and spread toward the opening, the uniformity of the electric field strength in the circumferential direction can be ensured. In addition, by having the directivity of the electric field strength so that the opening side toward the center of the processing container 2 becomes strong, the amount of microwave radiation that contributes to the plasma processing can be increased.

  Moreover, as shown on the vertical axis of FIG. 13, (2) if the radius on the inner peripheral side of the arc-shaped slot is any length in the range of 7 mm to 22 mm, the directivity of the electric field strength can be obtained. It turns out that it is preferable.

  From the above results, in the present embodiment, the circumferential length of the arc-shaped slot S is set to a value that is the same as or close to 1/2 of the wavelength λg of the microwave propagating in the slot S, and the radius of the slot S And the angle of the opening is optimized to an angle in the range of 30 ° to 120 °. As a result, the amount of microwave radiation that contributes to the plasma treatment can be maximized. Further, the radius R on the inner peripheral side of the slot S is optimized to a length of 7 mm to 22 mm with R = 12 mm as a reference. As a result, the amount of microwave radiation that contributes to the plasma treatment can be maximized.

The length of the arc-shaped slot S in the circumferential direction is set to a value that is the same as or close to 1/2 of the wavelength λg of the microwave propagating in the slot S. This is because the propagation efficiency of the microwave propagating through the slot S is increased by the presence wave being maximized.
[Slot optimization]
Based on the above simulation results, optimization of the slot S will be described with reference to FIGS. In FIG. 14, the slots are optimized from left to right. First, there is no bias in the electric field intensity distribution between the case where the leftmost slot S shown in FIG. 14 is ◯ -shaped and the case where the slot S shown on the right is △ -shaped, and antenna directivity is not obtained. I understand.

  Further, when the slot S shown on the right is C-shaped, the inner diameter R of the slot is larger than 22 mm, and the opening is smaller than 30 °, there is no bias in the electric field strength distribution, and the antenna directivity is obtained. I can't.

  Further, when the slot S shown on the right side is C-shaped, the slot radius R is larger than 22 mm, and the opening is larger than 120 °, there is no bias in the electric field strength distribution, and the antenna directivity is obtained. I can't.

  When the slot S shown in the rightmost part of FIG. 14 is C-shaped, the radius R of the slot is larger than 22 mm, and the opening is in the range of 30 ° to 120 °, the electric field strength distribution is slightly biased. The antenna has a little directivity.

  The rightmost state in FIG. 15 is exactly the same as the right end in FIG. The slot S shown on the rightmost left side of FIG. 15 has appropriate directivity. In this case, the slot S has a C shape, and the conditions (1) and (2) in the upper left of FIG. 13 are satisfied. In this case, there is an ideal bias in the electric field intensity distribution, and the directivity optimized for the antenna can be obtained. According to this, it is possible to increase the amount of microwave radiation that contributes to plasma processing by using the directivity of the antenna, and to improve the uniformity of the electric field strength. Further, the amount of microwave radiation consumed by the plasma in the wall of the processing container 2 or in the vicinity of the wall of the processing container 2 can be reduced, and abnormal discharge can be prevented.

  Each of the three slots S from the left in FIG. 15 is characterized by the shape on the opposite side of the opening of the slot S. In the central slot S of FIG. 15, the above-described notch S1 is formed on the opposite side of the opening. The second slot S from the left in FIG. 15 has a flat portion S2 on the opposite side of the opening. The flat portion S2 is narrower than the width of the slot S. Furthermore, the slot S shown in the leftmost part of FIG. 15 has a convex part S3. The convex portion S3 is larger than the width of the slot S. By forming the notch part S1, the flat part S2, and the convex part S3 on the opposite side of the opening part of the slot S, the electric field strength at the center of the slot S can be lowered and the directivity of the antenna can be further improved.

  Although the microwave plasma processing apparatus has been described in the above embodiment, the microwave plasma processing apparatus according to the present invention is not limited to the above embodiment, and various modifications and improvements can be made within the scope of the present invention. It is.

  For example, the arrangement of the microwave introduction mechanisms 63b to 63g in the outer peripheral portion may be a perfect circle or an ellipse. When the processing container 2 is an ellipse, it is preferable to arrange the microwave introduction mechanism 63 at the outer peripheral portion on the ellipse. On the other hand, when the processing container 2 is a perfect circle, it is preferable to arrange the microwave introduction mechanism 63 on the outer peripheral portion on the perfect circle. Thereby, it is possible to create a preferable bias toward the center side of the microwave electric field intensity distribution on the ceiling surface.

  In the above-described embodiment, the film forming apparatus and the etching apparatus are exemplified as the plasma processing apparatus. be able to.

  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 Microwave plasma processing apparatus 2 Processing container 3 Gas supply mechanism 4 Exhaust apparatus 5 Microwave introduction apparatus 8 Control part 11 Ceiling part 15 Gas introduction part 21 Mounting stand 25 High frequency power supply 31 Gas supply source 50 Microwave output part 60 Antenna unit 63 Microwave introduction mechanism 63a Microwave introduction mechanism 63b to 63g in the central portion Microwave introduction mechanism in the outer peripheral portion 65 Antenna 68 Microwave transmission path 71a Planar antenna 71b Planar antenna 72 Microwave slow wave material 73A to 73G Microwave transmission plate Sa slot Sb slot

Claims (8)

A microwave plasma processing apparatus that converts a gas into a plasma by using a microwave and performs plasma processing in a processing vessel,
Having three or more microwave introduction mechanisms on the ceiling of the processing vessel;
The microwave introduction mechanism is
A dielectric slow wave material that transmits microwaves;
An antenna of a conductive member having a slot on the lower surface of the slow wave material;
A dielectric microwave transmission window for introducing a microwave passed through the slot into the processing vessel;
When the microwave introduction mechanism is provided at the outer edge of the central portion of the processing container, the slot of the antenna has an arc shape, and an opening in which a part of the slot opens at a predetermined angle toward the central portion. Having a part,
Microwave plasma processing equipment. The predetermined angle of the opening of the slot is any angle in the range of 30 ° to 120 °.
The microwave plasma processing apparatus according to claim 1. The length in the circumferential direction of the slot is a value that is the same as or close to 1/2 of the wavelength λg of the microwave in the slot.
The microwave plasma processing apparatus according to claim 1 or 2. A radius on the inner peripheral side of the slot is any length in a range of 7 mm to 22 mm.
The microwave plasma processing apparatus as described in any one of Claims 1-3. The slot has a notch on the opposite side of the opening,
The microwave plasma processing apparatus as described in any one of Claims 1-4. The slot has a flat portion on the opposite side of the opening,
The microwave plasma processing apparatus as described in any one of Claims 1-4. The slot has a convex portion on the opposite side of the opening,
The microwave plasma processing apparatus as described in any one of Claims 1-4. A microwave introduction mechanism for introducing microwaves into a microwave plasma processing apparatus,
A dielectric slow wave material that transmits microwaves;
An antenna of a conductive member having a slot on the lower surface of the slow wave material;
A dielectric microwave transmission window for introducing a microwave passed through the slot into the processing container;
When provided at the outer edge than the central portion of the processing container, the slot of the antenna has an arc shape, and a part of the slot has an opening that opens at a predetermined angle toward the central portion.
Microwave introduction mechanism.