Microwave plasma CVD device

Abstract

A microwave plasma CVD apparatus (1) is provided with: a chamber (10A); a mounting table (110A) provided in the center of the chamber (10A) when the chamber (10A) is viewed in plan; a coaxial structure part (80A) including a center conductor (81) positioned in the center of the chamber (10A) in plan view of the chamber (10A) and parallel to the axial direction of the axis of symmetry of the internal resonance mode of the chamber (10A), and an outer conductor (82) positioned around the center conductor (81); a plurality of microwave introduction ports (20), (20),..., which are provided in a coaxial structure part (80A) of the chamber (10A), and which are coupled so as to match the internal resonance mode of the chamber (10A); and a microwave introduction window (30A) that transmits microwaves while pressure-isolating the chamber (10A) from the waveguide section (40A).

Description

Technical Field

[0001] The invention relates to a microwave plasma CVD device. This application claims priority based on Japanese Patent Application No. 2022-092952 and Japanese Patent Application No. 2022-092953 filed in Japan on June 8, 2022, and the contents of which are incorporated herein by reference. Background Art

[0002] Artificial diamonds used as raw materials for machining tools and abrasive particles in industry are almost all produced by ultra-high pressure synthesis, but in recent years, the use of gas phase synthesis has become popular. Diamonds produced by gas phase synthesis are mainly used for window materials, radiators, semiconductors, and quantum applications. In these applications, large areas and / or high purity are required.

[0003] As devices for gas phase synthesis, hot filament CVD (Chemical Vapor Deposition) devices and microwave plasma CVD devices are mainly used in industry. Among them, in the microwave plasma CVD device, microwaves with a frequency of 2.45 GHz or 915 MHz are used to induce microwave discharge in a gas mainly composed of methane and hydrogen at a pressure (vacuum degree) of 10 to 300 Torr, and diamond can be grown on a substrate by forming plasma. When the microwave plasma CVD device is used for diamond synthesis, it can achieve about 10 times higher growth speed than the hot filament CVD device, and it can be expected that the manufacturing cost will be reduced. In addition, since there is no filament material mixed in the film, it is possible to grow high-purity films required for semiconductor applications.

[0004] There are various methods for microwave plasma CVD devices, and the plasma shape is controlled by studying the shape of the chamber as a discharge vessel and the method of introducing microwaves. The main chamber shapes include the NIRIM type designed at the former Inorganic Materials Research Institute (now the National Research and Development Corporation Material Research Institute) (non-patent document 1), the ASTeX type developed by the American ASTeX company (patent document 1), the device called CYRANNUS commercialized by the German iPlas company (patent document 2), the device called AIXTRON developed by the German Fraunhofer Institute (non-patent document 2) and its variations (non-patent documents 3 to 5), etc. As another microwave introduction method, there is a method of supplying microwaves to the chamber from multiple waveguides at staggered irradiation times (patent document 3).

[0005] In addition, a mode converter for converting the mode of microwaves transmitted into the chamber is provided in the microwave plasma CVD apparatus. For example, there is a mode converter having a TE mode square waveguide and a TM mode cylindrical waveguide (Patent Documents 4 to 6). In addition, in the mode converter from the TE square waveguide to the TE cylindrical waveguide, there is a mode converter that converts once into a TM cylindrical waveguide and divides it into four parts, and then converts it into a large-diameter cylindrical waveguide by resynthesizing (Patent Documents 4 and 5). Prior art literature Patent Literature Patent Document 1: Japanese Patent No. 3483147 Patent Document 2: Japanese Patent Publication No. 2000-515296 Patent Document 3: Japanese Patent Application Laid-Open No. 4-144992 Patent Document 4: Japanese Patent Application Laid-Open No. 02-009202 Patent Document 5: Japanese Patent Application Laid-Open No. 10-126101 Patent Document 6: Japanese Patent Application Publication No. 2017-5533 Non-patent literature

[0007] Non-patent document 1: Journal of Crystal Growth, 62 (1983), 642-644. Non-patent document 2: Applied Physics Letters, 72, 1149, 1998 Non-patent document 3: Diamond & Related Materials, 30, (2012), 15-19 Non-patent document 4: Diamond & Related Materials, 51, (2015), 24-29 Non-patent document 5: Vacuum, 117, (2015), 112-120 Summary of the invention Technical problem to be solved by the invention

[0008] The microwave plasma CVD device is composed of at least a microwave power supply for generating microwaves, a chamber for synthesizing diamonds, and a waveguide for introducing microwaves from the microwave power supply to the chamber. In the high-speed growth of large-area diamonds using a microwave plasma CVD device, it is necessary to introduce high-power microwaves. However, in this case, abnormal discharges sometimes occur in the waveguide. In particular, in a high humidity environment, the generation of abnormal discharges becomes significant in the waveguide for introducing microwaves into the chamber, in the applicator formed by connecting a square waveguide and a cylindrical waveguide used in the ASTeX type and the like in the above-mentioned microwave plasma CVD device, etc.

[0009] In addition, when manufacturing large gemstones or semiconductor diamond ingots, sufficient space is required near the processed object (crystal) to provide mechanisms for cooling the crystal, automatically lifting and lowering the crystal, and managing the temperature distribution. Specifically, when the crystal is placed on a mounting table, it is preferred that there is no component below it that would obstruct the installation of the above-mentioned mechanisms, such as a microwave introduction unit.

[0010] Furthermore, in the NIRIM type, CYRANNUS, and AIXTRON of the above-mentioned microwave plasma CVD apparatus, since there is a microwave introduction window made of quartz or the like provided as a vacuum partition wall between the chamber and the outside on or near the extension line in the in-plane direction relative to the upper surface (growth plane) of the crystal, it is etched by plasma, and the quartz components floating due to etching are mixed into the diamond on the substrate, which may cause the quality of the processed body such as the bulk to be reduced. Such a phenomenon is considered to become more significant because the plasma diffuses and approaches the microwave introduction window when a high-power microwave is input.

[0011] In addition, in the high-speed growth of large-area diamond using a microwave plasma CVD device, it is necessary to introduce high-power microwaves. However, in the microwave mode converter as described above, when high-power microwaves are introduced, abnormal discharge may sometimes occur in the waveguide. In particular, the occurrence of abnormal discharge in the waveguide becomes significant in a high-humidity environment. In addition, in Patent Document 4, the waveguide has a multi-stage structure of square → cylinder → 4 square → 4 twisted tubes → 4 square → cylinder, which becomes a large and complex mode converter. In Patent Document 5, although it has the advantage of being able to increase the diameter without using a tapered tube, the mode converter is still large and complex. Furthermore, in recent years, in order to meet the demand for larger blocks, research and development of the structure and shape of the mode converter have been continuously advanced, but in Patent Document 6, the diameter of the cylindrical waveguide is about the long side of the square waveguide. In order to increase the diameter, it is necessary to further connect a tapered tube of a specified length, which leads to the complexity of the structure. Thus, when high-power microwaves are introduced into a microwave plasma CVD device, a chamber of an etching device, a radar antenna, etc., it is required to suppress abnormal discharge in the mode converter and to simplify and miniaturize the mode converter.

[0012] The present invention is proposed in view of such previous situations, and its purpose is to provide a microwave plasma CVD device that can suppress abnormal discharge even when high-power microwaves are introduced. In addition, by ensuring good access to the crystal, the crystal quality can be improved, thereby enabling the manufacture of high-purity diamonds.

[0013] In addition, another object of the present invention is to provide a microwave mode converter that can suppress abnormal discharge even when high-power microwaves are introduced, and can arbitrarily expand the diameter of the cylindrical waveguide or coaxial waveguide in the conversion part while achieving simplification and miniaturization. Solutions for solving technical problems

[0014] In order to achieve the above-mentioned object, the present invention provides the following means. [1] A microwave plasma CVD device, wherein the microwave plasma CVD device comprises: a chamber; a mounting table disposed at the center of the chamber when the chamber is viewed from above; a raw material gas inlet portion for introducing raw material gas into the chamber; a gas exhaust portion for exhausting gas from the chamber; a plurality of microwave introduction ports coupled in a manner matching an internal resonance mode of the chamber; one or more microwave introduction windows for isolating the chamber from a waveguide portion under pressure while allowing microwaves to pass therethrough; a waveguide portion connected to the plurality of microwave introduction ports; and a microwave oscillation source connected to the waveguide portion.

[0015] [2] According to the microwave plasma CVD device described in [1] above, the microwave plasma CVD device also has a coaxial structure, which includes a central conductor located in the center of the chamber when looking down at the chamber and parallel to the axial direction of the symmetry axis of the internal resonance mode of the chamber, and an external conductor located around the central conductor, and the multiple microwave introduction ports are arranged in the coaxial structure of the chamber.

[0016] [3] A microwave plasma CVD device according to [1] or [2] above, wherein the introduction direction of the microwaves introduced from the multiple microwave introduction ports is parallel to the axial direction of the symmetry axis of the internal resonance mode of the chamber or the axial direction of the central conductor.

[0017] [4] A microwave plasma CVD device according to the above [2], wherein the introduction direction of the microwaves introduced from the multiple microwave introduction ports is perpendicular to the axial direction of the symmetry axis of the internal resonance mode of the chamber or the axial direction of the central conductor.

[0018] [5] The microwave plasma CVD device according to [2] above, wherein the opening surfaces of the plurality of microwave introduction ports are arranged around the central conductor when looking down at the chamber, and are arranged parallel to the axial direction of the central conductor.

[0019] [6] The microwave plasma CVD device according to [2] above, wherein the opening surfaces of the plurality of microwave introduction ports are arranged around the central conductor when looking down at the chamber, and are set perpendicularly to the axial direction of the central conductor.

[0020] [7] A microwave plasma CVD device according to any one of [1] to [6] above, wherein the opening surfaces of the multiple microwave introduction ports are arranged along the circumference of the chamber based on the symmetry axis of the internal resonance mode of the chamber or the central axis of the central conductor when looking down at the chamber.

[0021] [8] A microwave plasma CVD device according to the above [2], wherein the waveguide portion has a square-shaped waveguide tube, and a ring-shaped resonator coupled to the square-shaped waveguide tube and arranged in the coaxial structure portion of the chamber, the ring-shaped resonator is coupled to the coaxial structure portion via the plurality of microwave introduction ports arranged in the resonator, and the TE mode of the microwave transmitted in the square-shaped waveguide tube is converted into a TEM mode transmitted in the coaxial structure portion via the ring-shaped resonator.

[0022] [9] A microwave mode converter, wherein the microwave mode converter comprises a square waveguide, a ring-shaped resonator coupled to the waveguide, and a coaxial structure coupled to the resonator, wherein the TE mode of microwaves propagating in the square waveguide is converted into a TEM mode propagating in the coaxial structure via the ring-shaped resonator.

[0023]

[10] The microwave mode converter according to [9] above, wherein the resonator has an outer peripheral side wall and an inner peripheral side wall, and has a plurality of microwave introduction ports arranged along the circumferential direction of the inner peripheral side wall.

[0024]

[11] A microwave mode converter according to the above

[10] , wherein the opening surfaces of the plurality of microwave introduction ports are arranged parallel to the axial direction of the symmetry axis of the resonator, and are arranged rotationally symmetrically along the circumferential direction of the inner circumferential side wall with respect to the symmetry axis of the resonator.

[0025]

[12] A microwave mode converter according to the above-mentioned

[10] or

[11] , wherein the microwave introduction port is a linear or rectangular slit, and the slit is configured corresponding to the resonant mode in the resonator so that its long side is parallel to the direction of the magnetic field in the slit, and the direction of the magnetic field formed by the slit in the coaxial structure is the same as the direction of the magnetic field in the coaxial structure. Effects of the Invention

[0026] According to the present invention, abnormal discharge can be suppressed even when high-power microwaves are introduced, and by ensuring good access to the crystal, the crystal quality can be improved, thereby enabling the manufacture of high-purity diamond.

[0027] In addition, according to the present invention, a microwave mode converter can be realized that can suppress abnormal discharge even when high-power microwaves are introduced. In addition, the diameter of the cylindrical waveguide or coaxial waveguide in the conversion part can be arbitrarily enlarged while realizing the simplification and miniaturization of the microwave mode converter. When it is applied to a microwave plasma CVD device, sufficient space required for manufacturing a large block or other processed body can be ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a partially cutaway perspective view showing an example of the structure of a microwave plasma CVD device according to an embodiment of the present invention. Figure 2 Yes means Figure 1 A side view of the structure of a microwave plasma CVD apparatus. Figure 3 (A) is a rough representation of Figure 1 A cross-sectional view of an example of the structure of a microwave plasma CVD device, Figure 3 (B) is a cross-sectional view along line AA. Figure 4 It means that it is located at Figure 1 A three-dimensional diagram of the structure of a microwave mode converter of a coaxial structure portion. Figure 5 (A) is Figure 4 Top view of the microwave mode converter. Figure 5 (B) is a cross-sectional view along line BB. Figure 6 (A) and Figure 6 (B) is a rough representation of Figure 3 (A) is a cross-sectional view of a modified example of the microwave plasma CVD apparatus. Figure 7 (A)~ Figure 7 (C) is a rough representation of Figure 3(A) is a cross-sectional view of another modified example of the microwave plasma CVD device. Figure 8 (A) is a general representation of Figure 7 (A) is a side view of an example in which the annular resonator is changed to a plurality of waveguides, Figure 8 (B) is a cross-sectional view along line CC. Fig. 9 This is a diagram showing the distribution of electric field intensity based on simulation in Example 1. Fig.10 (A) is a diagram showing the distribution of electric field intensity based on simulation of Example 2, Fig.10 (B) is a diagram showing the distribution of magnetic field intensity in the cross section along line DD. Fig.11 This is a perspective view showing the structure of a microwave mode converter in a conventional microwave plasma CVD apparatus. Fig.12 This is a diagram showing the distribution of electric field intensity according to Comparative Example 1 based on simulation. DETAILED DESCRIPTION

[0029] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0030] In addition, in the drawings used in the following description, in order to facilitate observation of each component, the scale of the size is sometimes expressed differently according to the component, and the size ratio of each component is not necessarily the same as the actual one. In addition, the materials and the like exemplified in the following description are just one example, and the present invention is not necessarily limited to these, and can be appropriately changed and implemented within the scope of not changing its purpose.

[0031] Figure 1 is a partially cutaway perspective view showing an example of the structure of a microwave plasma CVD device according to an embodiment of the present invention. Figure 2 Yes means Figure 1 A microwave plasma CVD device 1 is a device for generating plasma to deposit or accumulate a substance such as diamond on a workpiece such as a substrate.

[0032] like Figure 1 as well as Figure 2As shown, the microwave plasma CVD device 1 comprises: a chamber 10A; a mounting table 110A, which is arranged at the center of the chamber 10A when the chamber 10A is viewed from above; a coaxial structure 80A, which is located at the center of the chamber 10A when the chamber 10A is viewed from above, and includes a central conductor 81 parallel to the axial direction of the symmetry axis Z1 of the internal resonance mode of the chamber 10A and an external conductor 82 located around the central conductor 81; a plurality of microwave introduction ports 20, 20, ..., which are arranged in the coaxial structure 80A of the chamber 10A and coupled in a manner matching the internal resonance mode of the chamber 10A; a microwave introduction window 30A, which allows microwaves to pass through while isolating the chamber 10A from a waveguide part described later under pressure; a waveguide part 40A, which is connected to the plurality of microwave introduction ports 20, 20, ...; and a microwave oscillation source 50, which is connected to the waveguide part 40A.

[0033] The mounting table 110A can be arranged at the upper end of the center conductor 81 in the axial direction, for example, it can also be arranged on the upper surface of the chamber 10A opposite to the upper end of the center conductor 81 in the axial direction. From the viewpoint that the microwave introduction window 30A is not exposed to the plasma, it is preferred that the upper end of the center conductor 81 in the axial direction is located above the bottom surface of the chamber 10A. The mounting table 110A is not particularly limited as long as it can stably mount the workpiece W. From the viewpoint that it is a conductive material and a heat-resistant material and is difficult to be etched by plasma, it is preferably composed of molybdenum (Mo) and the like. In addition, the mounting table 110A can also have a multilayer structure composed of multiple layers including different materials. As a multilayer structure, there is no particular limitation, for example, it can be a 2-layer structure, the lower layer is composed of copper (for water cooling), and the upper layer is composed of molybdenum. In addition, it can also be a 3-layer structure, the bottom layer is composed of copper (for water cooling), the middle layer is composed of SUS, and the top layer is composed of molybdenum.

[0034] The chamber 10A has at least Figure 2 as well as Figure 3 The bottom wall 11 and the side wall 12 shown have Figure 1 to Figure 3 The chamber 10A is a sealed container of the sealed space S1 shown. The chamber 10A is made of metal such as stainless steel or aluminum alloy, and has an observation window (quartz, heat-resistant glass) as required. In the present embodiment, the chamber 10A has a uniaxially symmetrical shape, which is a rotationally symmetrical shape with the symmetry axis Z1 parallel to the z direction as a reference. The chamber 10A is, for example, roughly cylindrical in a top view, but is not limited to this.

[0035] The microwave plasma CVD device 1 includes a raw material gas inlet 60 for introducing a raw material gas into the chamber 10A and a gas exhaust part 70 for exhausting the gas from the chamber 10A. The raw material gas inlet 60 supplies the raw material gas, which is the raw material of the film formed on the workpiece W, into the closed space S1 of the chamber 10A. The raw material gas is, for example, a mixed gas with methane (CH4) and hydrogen (H2) as main components. The above-mentioned raw material gas may further contain argon (Ar) and oxygen (O2). In addition, for the purpose of intentionally doping as impurities, it may further contain compounds containing nitrogen (N2), phosphorus (P), boron (B), etc. The gas exhaust part 70 has a pump for exhausting the gas in the closed space S1 and an exhaust resistance controller not shown in the figure. By driving the pump, the closed space S1 can be maintained in a reduced pressure state (preferably a vacuum state) with a constant pressure.

[0036] Figure 3 (A) is a rough representation of Figure 1 A cross-sectional view of an example of the structure of a microwave plasma CVD device, Figure 3 (B) is a cross-sectional view along line AA.

[0037] In the present embodiment, a coaxial opening 13 is provided on the bottom wall 11 of the chamber 10A, which is connected to a plurality of microwave introduction ports 20, 20, ... provided on the coaxial structure 80A. When the chamber 10A is viewed from above, the opening surface of the coaxial opening 13 is arranged around the central conductor 81 and is provided perpendicularly to the axial direction (z direction) of the central conductor 81. The coaxial opening 13 has, for example, an annular shape and is provided in a manner such that the axial direction is parallel to the axial direction (z direction) of the central conductor 81.

[0038] When the chamber 10A is viewed from above, the opening surface of the coaxial opening 13 is arranged coaxially with respect to the central axis of the central conductor 81 of the chamber 10A. The coaxial opening 13 has a circumferential direction and a radial direction, and is provided so that the circumferential direction is along the circumferential direction of the chamber 10A.

[0039] In this embodiment, the microwave introduction window 30A is placed on the bottom wall 11 of the chamber 10A so as to cover the coaxial opening 13. The microwave introduction window 30A is provided between the chamber 10A (decompression region) and the waveguide 40A (atmospheric pressure region) (see Figure 1 as well as Figure 2 The microwave introduction window 30A is preferably made of a material (dielectric) that transmits microwaves without loss, such as quartz.

[0040] The microwave introduction window 30A is also provided in parallel with the axial direction of the symmetry axis of the internal resonance mode of the chamber 10A or the axial direction of the central conductor 81 when the chamber 10A is viewed from above, similarly to the coaxial opening 13. The microwave introduction window 30A is not limited to an annular shape as long as it is axially symmetrical and can close the coaxial opening 13, and may have other shapes than the annular shape.

[0041] Figure 2 The waveguide portion 40A shown transmits microwaves from the microwave oscillation source 50 to the chamber 10A via a plurality of microwave introduction ports 20, 20, ... Figure 3 As shown, the waveguide portion 40A is coupled to a square waveguide tube 411 and has a ring-shaped resonator 412 provided in a coaxial structure 80A of the chamber 10A. The coaxial structure 80A and the ring-shaped resonator 412 constitute a microwave mode converter 41. The ring-shaped resonator 412 is coupled to the coaxial structure 80A via a plurality of microwave introduction ports 20, 20, ... provided in the resonator.

[0042] exist Figure 3 In the structure shown, the internal resonance mode is axisymmetric, and the introduction direction of the microwave introduced from the plurality of microwave introduction ports 20, 20, ... is perpendicular to the axial direction of the symmetry axis of the internal resonance mode of the chamber 10A or the axial direction of the central conductor 81. In other words, the normal line of the center of the opening surface of the plurality of microwave introduction ports 20, 20 is perpendicular to the above-mentioned symmetry axis. In addition, the opening surfaces of the plurality of microwave introduction ports 20, 20, ... are arranged around the central conductor 81 when looking down at the chamber 10A, and are set parallel to the axial direction of the central conductor 81. When the microwaves are introduced from the plurality of microwave introduction ports 20, 20, ... to the coaxial structure 80A described later in the direction perpendicular to the above-mentioned symmetry axis, the microwaves then pass through the microwave introduction window 30A of the coaxial opening 13 and travel to the upper part of the chamber 10A.

[0043] Figure 4 It means that it is located at Figure 1 A perspective view of the structure of the microwave mode converter 41 of the coaxial structure portion 80A, Figure 5 (A) is Figure 4 A top view of the microwave mode converter 41, Figure 5 (B) is a cross-sectional view along line BB. The microwave mode converter 41 has a square waveguide 411, a ring-shaped resonator 412 coupled to the waveguide 411, and a coaxial structure 413 coupled to the resonator 412. The microwave mode converter 41 has the square waveguide 411 and the coaxial structure 413, so it can also be called a mode conversion joint, i.e., an applicator. However, the applicator of this embodiment is very different from the conventional applicator in that it has a ring-shaped resonator.

[0044] One end 411a of the waveguide 411 is connected to the circulator 90 (microwave oscillation source 50 side), and the other end 411b is connected to the resonator 412. The waveguide 411 has a rectangular shape in a cross-section perpendicular to the microwave propagation direction and a straight shape in a plan view.

[0045] The resonator 412 has an outer peripheral side wall 412A and an inner peripheral side wall 412B, and the other end 411b of the waveguide 411 is connected to the outer peripheral side wall 412A. The resonator 412 is rectangular in cross-section in a direction perpendicular to the propagation direction of the microwave, and has a perfect circular shape when viewed from above. In addition, the resonator 412 has a plurality of microwave introduction ports 412C, 412C, ... arranged along the circumferential direction of the inner peripheral side wall 412B. In the present embodiment, the plurality of microwave introduction ports 412C, 412C, ... constitute a plurality of microwave introduction ports 20, 20, ..., but it is not limited thereto, and a plurality of microwave introduction ports 412C, 412C, ... and a plurality of microwave introduction ports 20, 20, ... may also be provided separately and directly connected.

[0046] The opening surfaces of the plurality of microwave introduction ports 412C, 412C, ... are arranged parallel to the axial direction (z direction) of the symmetry axis of the resonator 412, for example, the axial direction of the central conductor 81, and are arranged to be rotationally symmetrical along the circumferential direction of the inner peripheral side wall 412B with the symmetry axis of the resonator 412 as a reference. For example, the opening surfaces of the four microwave introduction ports 412C, 412C are arranged in a manner of 90° rotational symmetry along the circumferential direction of the inner peripheral side wall 412B. The opening surfaces of the plurality of microwave introduction ports 412C, 412C, ..., for example, have long sides and short sides, the long sides are arranged along the circumferential direction of the inner peripheral side wall 412B, and the short sides are arranged along the axial direction of the central conductor 81. The opening surfaces of the plurality of microwave introduction ports 412C, 412C, ... are preferably of the same shape, but may also be of different shapes within a range that does not affect the radiation of microwaves.

[0047] The microwave introduction port 412C is typically a linear or rectangular slit. The slit is arranged corresponding to the resonance mode in the resonator 412 so that its long side is parallel to the direction of the magnetic field in the slit or the vicinity of the slit, and the direction of the magnetic field formed by the slit in the coaxial structure 413 is the same as the direction of the magnetic field in the coaxial structure 413. The slit is, for example, rectangular, but may also have a long hole shape or the like.

[0048] The coaxial structure 413 has an outer peripheral side wall 413A and an inner peripheral side wall 413B, forming the coaxial structure 80A of the chamber 10A. One end 413a of the coaxial structure 413 is connected to the resonator 412 via a plurality of microwave introduction ports 20, 20, ..., and the other end 413b becomes the coaxial opening 13 of the chamber 10A (see Figure 3(A)). In the present embodiment, the inner side wall 413B constitutes the central conductor 81, and the outer side wall 413A constitutes the outer conductor 82. The coaxial structure 413 has a ring shape when viewed in a cross-section in a direction perpendicular to the propagation direction of the microwave. In addition, in the present embodiment, the outer side wall 413A of the coaxial structure 413 forms the same surface as the inner side wall 412B of the resonator 412. Therefore, in other words, it can also be said that a plurality of microwave introduction ports 412C, 412C, ... are provided on the outer side wall 413A of the coaxial structure 413, and are arranged along its circumferential direction.

[0049] In the microwave mode converter 41 constructed as described above, the microwave introduced from one end 411a of the waveguide 411 is introduced into the resonator 412 from the other end 411b, and then transmitted from a plurality of microwave introduction ports 412C, 412C, ... provided on the inner peripheral side wall 412B of the resonator 412 to the coaxial structure 413. Thus, the TE (Transverse Electric) mode of the microwave transmitted in the square-shaped waveguide 411 is converted into the TEM (Transverse Electromagnetic) mode transmitted in the coaxial structure 413 via the annular resonator 412. In addition, the TE mode generally refers to a propagation mode in which the electric field direction is orthogonal to the direction of travel of the electromagnetic wave, and the TEM mode generally refers to a propagation mode in which both the electric field direction and the magnetic field direction are orthogonal to the direction of travel of the electromagnetic wave. In the case of the present embodiment, the TE mode refers to the basic mode TE10, for example. In this case, the magnetic field distribution in the chamber 10A becomes axisymmetric (circular).

[0050] In this way, the microwave mode converter 41 has a ring-shaped resonator 412, and the resonator 412 has a plurality of microwave introduction ports 412C, 412C, ... arranged in a circumferential direction of the inner peripheral side wall 412B, so that the microwaves in the resonance mode are introduced into the coaxial structure 413 from the plurality of microwave introduction ports 412C, 412C, .... Thus, the concentration of the electric field intensity in the microwave mode converter 41 can be suppressed, and the probability of abnormal discharge in the waveguide can be reduced. In addition, compared with the existing microwave mode converter, the structure of the microwave mode converter 41 can be simplified and miniaturized. Furthermore, since the microwave mode converter 41 has a ring-shaped resonator 412, the coaxial structure 413 (particularly the inner peripheral side wall 413B) can be enlarged in diameter, and as a result, sufficient space can be ensured below the processed object for a mechanism that can cool the processed object (crystal), automatically lift and lower, and manage the temperature distribution, etc., which is required when manufacturing a large block or other processed object.

[0051] In addition, the microwave plasma CVD device 1 includes a circulator 90 and an EH tuner 100 provided in the waveguide portion 40A. The circulator 90 has a first port 91 coupled to the microwave oscillation source 50 side, a second port 92 coupled to the chamber 10A side, and a third port 93 different from the first port 91 and the second port 92. The circulator 90 receives microwaves from the microwave oscillation source 50 through the first port 91, and propagates the microwaves to the second port 92. In addition, the circulator 90 propagates the microwaves received through the second port 92, that is, the microwaves reflected from the microwave propagation component connected to the second port 92, to the third port 93. A non-reflection absorption end called a dummy load is connected to the third port 93, and the microwaves propagated to the third port 93 are completely absorbed and converted into heat. As a result, the microwaves reflected from the microwave propagation component connected to the second port 92 are completely absorbed by the dummy load, so that the microwaves do not return to the microwave oscillation source 50 side. As a method of using such a circulator 90 and a dummy load, a common method for preventing a microwave oscillator (magnetron, etc.) from being thermally damaged by reflecting microwaves can be used. Thus, the microwave generated by the microwave oscillator 50 is supplied to the waveguide portion 40A in one direction. The EH tuner 100 includes an E tuner portion 101 and an H tuner portion 102, and the impedance is adjusted by moving the plungers of the E tuner portion 101 and the H tuner portion 102 in and out. The EH tuner 100 is an example of a method for adjusting impedance, and other methods, such as a three-stub tuner, can be used.

[0052] The microwave oscillator 50 oscillates a predetermined frequency, for example, a microwave of 2.45 GHz or 915 MHz as an ISM band. As the microwave oscillator 50, for example, a magnetron or a semiconductor oscillator is used. In addition, in the microwave plasma CVD device 1 of the present embodiment, a cooling path using a medium such as cooling water or air may be provided above, on the side, and below the chamber 10A.

[0053] In the microwave plasma CVD device 1 configured as described above, microwaves supplied from the microwave oscillation source 50 are introduced into the chamber 10A through the plurality of microwave introduction ports 20, 20, ... provided in the coaxial structure 80A of the chamber 10A. The microwaves are irradiated to the raw material gas in the chamber 10A to discharge it, thereby generating plasma in the chamber 10A. Then, a coating of diamond or the like is formed on the surface of the workpiece W provided near the plasma by the raw material gas decomposed by the plasma.

[0054] As described above, according to the present embodiment, the plurality of microwave introduction ports 20, 20, ... are provided in the coaxial structure 80A of the chamber 10A, and are coupled in a manner matching the internal resonance mode of the chamber 10A including the coaxial structure 80A. Therefore, by introducing microwaves from the plurality of microwave introduction ports 20, 20, ... into the chamber 10A, the waveguide 40A ( Figure 2 ) and the electric field concentration in the coaxial structure 80A can suppress abnormal discharge and the accompanying heating even when high-power microwaves are introduced, thereby improving power efficiency.

[0055] In addition, the central conductor 81 at the bottom of the workpiece W can be thickened as needed, so that the mechanisms required for managing the crystal growth environment such as lifting, cooling / heating, and temperature (distribution) control of the large-area workpiece W can be assembled at the bottom of the substrate electrode, thereby improving the crystal quality and achieving uniform synthesis of large-area substrates and synthesis of thicker block crystals.

[0056] In addition, since plasma is generated above the mounting table 110A, the microwave introduction window 30A is provided at a position not exposed to the plasma generated in the chamber 10A, and thus the microwave introduction window 30A can be prevented from being etched by plasma. As a result, it is possible to prevent silicon and other elements constituting the microwave introduction window from being mixed into the workpiece W, and for example, a high-purity thin film of diamond and the like can be synthesized, and the quality of a bulk or other processed object can be improved. Furthermore, even if a high-power microwave is supplied, the plasma does not approach the microwave window, and thus a high-power microwave can be supplied, and the film forming area of ​​the workpiece W can be expanded, and thus a large-scale bulk or other processed object can be manufactured while suppressing the enlargement of the device.

[0057] Figure 6 (A) and Figure 6 (B) is a rough representation of Figure 3 (A) is a cross-sectional view of a modified example of the microwave plasma CVD apparatus 1 . Figure 7 (A)~ Figure 7 (C) is a rough representation of Figure 3 (A) is a cross-sectional view of another modified example of the microwave plasma CVD apparatus 1 . Figure 6 (A) and Figure 6 The microwave introduction method in the structure of (B) and Figure 1 to Figure 5 The microwave introduction method in the structure is the same, that is, the microwave introduction direction from the annular resonator 412 provided in the coaxial structure 80B or the coaxial structure 80C is perpendicular to the axis of each coaxial structure. In addition, Figure 7 (A)~ Figure 7(C) shows a structure in which the microwave introduction direction from the annular resonator 412 provided in the coaxial structure 80D, the coaxial structure 80E, or the coaxial structure 80F is parallel to the axis of each coaxial structure.

[0058] like Figure 6 As shown in (A), the microwave introduction window 30A is arranged below the mounting table 110B. That is, it is preferred that the mounting surface of the mounting table 110B, that is, the mounting position of the workpiece W and the installation position of the microwave introduction window 30A are offset in the axial direction (z-axis direction) of the symmetry axis of the chamber 10B.

[0059] In addition, you can also Figure 6 As shown in (B), the stage 110C has an outer diameter larger than the outer diameter of the central conductor 81 of the coaxial structure 80C of the chamber 10C, and the microwave introduction window 30B is arranged below the stage 110C and extends along the axial direction of the symmetry axis of the chamber 10C. In this case, the microwave introduction window 30B has, for example, a cylindrical shape, and the closed space S1 of the chamber 10C and the lower space S2 of the stage 110C are isolated by pressure through the microwave introduction window 30B. Plasma is generated above the stage 110C, and the microwave introduction window 30B is arranged below the stage 110C and is shielded by the stage 110C and not exposed to the plasma, so that the microwave introduction window 30B can be prevented from being etched by the plasma.

[0060] Figure 7 In (A), a plurality of microwave introduction ports 20, 20, ... are provided in the coaxial structure 80D of the chamber 10D, and are coupled in a manner matching the internal resonance mode of the chamber 10D. The introduction direction of the microwaves introduced from the plurality of microwave introduction ports 20, 20, ... is parallel to the axial direction of the symmetry axis of the internal resonance mode of the chamber 10D or the axial direction of the central conductor 81. At this time, the opening surfaces of the plurality of microwave introduction ports 20, 20, ... are arranged around the central conductor 81 when looking down at the chamber 10D, and are arranged perpendicular to the axial direction of the central conductor 81. The plurality of microwave introduction ports 20, 20, ... are provided in a part of the coaxial structure 80, that is, the bottom wall 11 of the chamber 10D. The plurality of microwave introduction ports 20, 20, ... are provided directly above the plurality of microwave introduction ports 412C, 412C, ... provided at the annular resonator 412. A mounting table 110D is provided at the upper end of the central conductor 81.

[0061] In addition, the annular resonator 412 is arranged directly below the chamber 10D. The annular resonator 412 has a plurality of microwave introduction ports 412C, 412C, ... provided on the upper surface of the annular resonator 412. The plurality of microwave introduction ports 412C, 412C, ... are directly connected to the plurality of microwave introduction ports 20. The opening surface of the microwave introduction port 412C of the annular resonator 412 and the opening surface of the microwave introduction port 20 are arranged perpendicularly to the axial direction (z direction) of the central conductor 81. In the present embodiment, the plurality of microwave introduction ports 412C, 412C, ... and the plurality of microwave introduction ports 20, 20, ... are provided separately, but the plurality of microwave introduction ports 412C, 412C, ... may also constitute the plurality of microwave introduction ports 20, 20, ...

[0062] In addition, if Figure 7 As shown in (B), the stage 110E may have an outer diameter larger than that of the central conductor 81, and the microwave introduction window 30B may be disposed below the chamber 10E and extend axially along the axis of symmetry of the chamber 10E. In this case, the microwave introduction window 30B may have a cylindrical shape, for example, and the closed space S1 of the chamber 10E and the lower space S2 of the stage 110E are pressure-isolated by the microwave introduction window 30B. Plasma is generated above the stage 110E, and the microwave introduction window 30B is disposed below the stage 110E and is shielded by the stage and not exposed to the plasma, so that the microwave introduction window 30B can be prevented from being etched by the plasma.

[0063] In addition, if Figure 7 As shown in (C), the central conductor 81 of the support stage 110F may also extend downwardly of the chamber 10F. In this case, the annular resonator 412 is disposed at the lower portion of the chamber 10F, and the microwave introduction port 20 is disposed on the radial (x-direction) side of the central conductor 81. By changing the length of the coaxial structure 80F extending downwardly, the resonance mode in the chamber 10F can be adjusted.

[0064] Thus, according to the above Figure 7 In the embodiment shown in (A), plasma is generated above the mounting table 110D, and the microwave introduction window 30A is provided below the mounting table 110D, so that the microwave introduction window 30B can be prevented from being etched by plasma. Figure 7 (B) and Figure 7In the embodiment shown in (C), plasma is generated above the stage 110E, and the microwave introduction window 30B is provided below the stage 110E and is shielded by the stage 110E and is not exposed to the above-mentioned plasma, so that the microwave introduction window 30B can be further suppressed from being etched by the plasma. In addition, similarly, plasma is generated above the stage 110F, and the microwave introduction window 30B is provided below the stage 110F and is shielded by the stage 110F and is not exposed to the above-mentioned plasma, so that the microwave introduction window 30B can be further suppressed from being etched by the plasma.

[0065] exist Figure 3 to Figure 6 In the microwave plasma CVD apparatus shown, a waveguide may be individually connected to each microwave introduction port instead of the ring-shaped resonator for introducing microwaves from a plurality of ports.

[0066] exist Figure 8 For example, Figure 7 (A) is an example in which the ring-shaped resonator is replaced with a plurality of waveguides.

[0067] Figure 8 (A) is a rough representation of Figure 6 (A) is a side view of a modified example of the microwave plasma CVD apparatus, Figure 8 (B) is a cross-sectional view along line CC. Figure 8 (A) and Figure 8 (B) The structure of the microwave plasma CVD device Figure 6 The structures of the microwave plasma CVD devices of (A) are basically the same, and the common parts are denoted by the same reference numerals and the description thereof is omitted, and the different parts are described below.

[0068] like Figure 8 (A) and Figure 8 As shown in (B), the microwave plasma CVD device 1 comprises: a plurality of microwave introduction ports 20, 20, ..., provided in a coaxial structure 80G of the chamber 10G, coupled in a manner matching the internal resonance mode of the chamber 10G; and a plurality of microwave introduction windows 30C, 30C, ..., which isolate the pressure between the chamber 10G and the waveguide portion 40B while allowing microwaves to pass through. The waveguide portion 40B is composed of, for example, a plurality of square waveguide tubes. In the present embodiment, four square waveguide tubes are arranged around the symmetry axis of the chamber 10G. Figure 8 (A) and Figure 8In the structure shown in (B), microwaves are introduced from the plurality of microwave introduction ports 20, 20, ... in parallel to the axial direction of the symmetry axis of the internal resonance mode of the chamber 10G. In the vicinity of the opening surface of the plurality of microwave introduction ports 20, 20, ..., the waveguide portion 40B is coupled to the chamber 10G in such a manner that the direction M of the magnetic field of the internal resonance mode of the chamber 10G matches the direction M of the magnetic field in each square waveguide of the waveguide portion 40B of the TE mode.

[0069] In the present embodiment, the internal resonance mode of the chamber 10G is axisymmetric, and the introduction direction of the microwaves introduced from the plurality of microwave introduction ports 20, 20, ... is parallel to the symmetry axis of the internal resonance mode of the chamber 10G. In other words, the normal to the center of the opening surface of the plurality of microwave introduction ports 20, 20 is parallel to the symmetry axis. At this time, the opening surfaces of the plurality of microwave introduction ports 20, 20, ... are arranged perpendicularly to the axial direction (z direction) of the symmetry axis of the internal resonance mode of the chamber 10G when the chamber 10G is viewed from above. The opening surfaces of the plurality of microwave introduction ports 20, 20, ... have, for example, long sides and short sides, and the in-plane direction of the opening surface defined by the long sides and the short sides is arranged perpendicularly to the axial direction (z direction) of the symmetry axis of the above-mentioned internal resonance mode. The plurality of microwave introduction ports 20, 20, ... are preferably of the same shape, but may also be of different shapes within a range that does not affect the radiation of the microwaves.

[0070] The opening surfaces of the plurality of microwave introduction ports 20, 20, ... are arranged along the circumferential direction of the chamber 10G with the symmetry axis of the internal resonance mode of the chamber 10G as a reference when looking down at the chamber 10G. For example, the opening surfaces of the four microwave introduction ports 20, 20, ... are arranged in a manner of 90° rotational symmetry along the circumferential direction of the chamber 10G. The opening surface of the microwave introduction port 20, for example, has a long side and a short side, and is arranged in a manner of the long side direction along the circumferential direction of the chamber 10G, and the short side is arranged along the axial direction of the symmetry axis of the above-mentioned internal resonance mode.

[0071] The microwave introduction port 20 is typically a linear or rectangular slit. The long side of the slit is arranged parallel to the direction of the magnetic field M near the slit. As a result, an electric field parallel to the short side of the slit is generated, and the slit functions as an antenna that radiates electromagnetic waves from its opening. The slit is, for example, in an arc shape, but may also have a rectangular shape, a long hole shape, etc.

[0072] In the present embodiment, a plurality of microwave introduction windows 30C, 30C, ... are placed on the bottom wall 11 of the chamber 10G so as to cover a plurality of microwave introduction ports 20, 20, .... The plurality of microwave introduction windows 30C, 30C, ... are provided between the chamber 10G (decompression region) and the waveguide 40B (atmospheric pressure region).

[0073] The plurality of microwave introduction windows 30C, 30C, ... are also arranged along the circumferential direction of the chamber 10G with the symmetry axis of the internal resonance mode of the chamber 10G as a reference when the chamber 10G is viewed from above, similarly to the plurality of microwave introduction ports 20, 20, ... For example, the four microwave introduction windows 30C, 30C, ... are arranged in a manner of 90° rotational symmetry along the circumferential direction of the chamber 10G. The microwave introduction window 30C is not limited to an arc shape as long as it can close the microwave introduction port 20, and may have a rectangular shape, a long hole shape, etc., or may have a single annular shape without being divided.

[0074] In this way, the microwave plasma CVD device 1 may also be configured to introduce microwaves into the chamber 10G through a waveguide portion 40B composed of, for example, a plurality of square waveguides. In this case, microwaves are introduced into each microwave introduction port at the same phase. According to this configuration, abnormal discharge in the waveguide portion 40B can also be suppressed, and the crystal quality can be improved by ensuring good access to the crystal, and a large bulk or other processed object can be manufactured.

[0075] Fig. 9 This is a diagram showing the distribution of electric field intensity based on the simulation of Example 1. Fig.10 (A) is a diagram showing the distribution of electric field intensity based on the simulation of Example 2, Fig.10 (B) is a diagram showing the distribution of magnetic field intensity in the cross section along line DD. Fig.11 This is a perspective view showing the structure of a microwave mode converter in a conventional microwave plasma CVD apparatus. Fig.12 This is a diagram showing the distribution of electric field intensity according to Comparative Example 1 based on simulation.

[0076] As Example 1, a simulation is performed to design Figure 6 The structure shown in (A) is the same as that shown in the figure, and numerical calculation is performed to calculate the electric field intensity distribution. The simulation software used is JMAG-Studio (made by JSOL). As the calculation method, the finite element method and the iteration method are used. The number of elements is about 1 million (tetrahedral mesh), the model size is 1m×0.4m×0.3m, the frequency of the microwave input is 2.45GHz, the mode is TE10, and the boundary conditions are that the input and output ports (rectangular waveguide ends) of the microwave input and the microwave introduction window are ideal conductors. exist Fig. 9 In the example, the electric field strength calculated by simulation is expressed as grayscale. In addition, the electric field strength corresponding to the substrate installation portion is calculated as the measurement area of ​​the electric field strength. Fig. 9 The electric field strength at area A in the figure and the electric field strength at area B corresponding to the waveguide or coaxial structure.

[0077] As Example 2, a structure is designed in which the radial width of the coaxial structure portion is larger than that of Example 1 ( Fig.10 (A)), numerical calculation is performed in the same manner as in Example 1 to calculate the electric field intensity distribution. In addition, Fig.10 In (B), the arrow indicates Fig.10 The calculation result of the magnetic field intensity distribution in the DD section of the annular resonator of (A) and the approximate direction of the magnetic field lines in the annular resonator and the coaxial structure. The microwave introduction port provided in the inner periphery of the annular resonator is arranged in a plurality of ways so that the directions of the respective magnetic field lines match at the boundary between the annular resonator and the coaxial structure. As a result, the TE mode of the microwave propagating in the square waveguide is converted into the TEM mode propagating in the coaxial structure via the annular resonator.

[0078] In addition, as Comparative Example 1, a microwave mode converter provided in a conventional microwave plasma CVD device was used. In the conventional ASTeX6500 type microwave plasma CVD device, microwaves are transmitted through the microwave mode converter 300 ( Fig.11 ) is introduced into the resonator-type cavity, and a predetermined electric field strength is obtained at the substrate setting portion. That is, the conventional microwave mode converter has a square-shaped waveguide and a coaxial line without a ring-shaped resonator. As a comparative example 1, a structure corresponding to the conventional microwave mode converter is designed ( Fig.12 ), perform numerical calculations, and calculate the electric field intensity distribution. Table 1 shows calculation results of the electric field intensity in region A and region B of Examples 1 to 2 and Comparative Example 1, and the ratio of the electric field intensity in region A to the electric field intensity in region B (specific intensity).

[0079] [Table 1]

[0080] According to the results in Table 1, in Example 1, when microwaves are introduced into the chamber from a square waveguide via a ring-shaped resonator having a plurality of slits on the side wall, a high electric field intensity equivalent to that of Comparative Example 1 can be obtained in region A, i.e., the substrate installation portion. In addition, the ratio (specific intensity) of the electric field intensity in region A to the electric field intensity in region B is 0.2 to 0.3, and it can be seen that the probability of occurrence of abnormal discharge in region B, i.e., the waveguide, can be reduced compared to Comparative Example 1.

[0081] In Example 2, even if the radial width of the coaxial structure is larger than that of Example 1, a higher electric field intensity can be obtained in region A, i.e., the substrate installation portion, which is equivalent to that in Comparative Example 1. In addition, the ratio (specific intensity) of the electric field intensity in region A to the electric field intensity in region B is 0.7 to 2.5, which is significantly larger than the specific intensity in Example 1, and it can be seen that the probability of occurrence of abnormal discharge in region B, i.e., the waveguide, can be further reduced.

[0082] On the other hand, in Comparative Example 1, if microwaves are introduced into the coaxial line from a square waveguide without passing through a resonator, the ratio of the electric field intensity in region A to the electric field intensity in region B (specific intensity) is 0.05 to 0.3. It can be seen that the probability of abnormal discharge is higher than that in either Example 1 or Example 2.

[0083] In addition, the present invention is not necessarily limited to the above-described embodiment, and various modifications can be added without departing from the gist of the present invention.

[0084] For example, in this embodiment, Figure 3 In the structure, the coaxial structure 80A is provided on the bottom wall 11 of the chamber 10A, but it is not limited to this. As long as the coaxial structure is coupled in a manner that matches the internal resonance mode of the chamber 10A, and the microwave introduction window 30A is provided at a position that is not exposed to the plasma generated in the chamber 10, there is no particular limitation on the setting position of the coaxial structure and the microwave introduction window 30A. The microwave introduction window 30A can also be provided at a position other than the extension line of the in-plane direction of the workpiece W and its vicinity. In addition, the microwave introduction window 30A can also be shown as being provided at a position of the bottom wall 11 that is visually undesirable from the workpiece W or a position of the bottom wall 11 that cannot be seen from the workpiece W. Thereby, the diamond deposited or grown on the workpiece W can be highly purified while suppressing the etching of the microwave introduction window by the plasma generated on the workpiece W.

[0085] The waveguide unit 40A may not have the coaxial structure 413, but may have a square waveguide 411 and a ring-shaped resonator 412 coupled to the waveguide 411. In this case, the resonator 412 may have one or more microwave introduction ports on the upper surface of the resonator 412, and may also function as a coaxial waveguide. More specifically, Figure 7 In the structure of (A), the microwave plasma CVD device 1 may not have the coaxial structure 80D, and the mounting table 110D may be provided on the bottom wall 11 of the chamber 10D. In this case, the microwave plasma CVD device 1 may also include: a raw material gas introduction part 60 for introducing the raw material gas into the chamber 10D (see Figure 1 , Figure 2); a plurality of microwave introduction ports 20, 20, ..., coupled in a manner matching the internal resonance mode of the chamber 10D; a microwave introduction window 30A, which isolates the chamber 10D from the waveguide pressure while allowing microwaves to pass through (refer to Figure 1 , Figure 2 ); waveguide portion 40A, connected to a plurality of microwave introduction ports 20, 20, ... (reference Figure 1 , Figure 2 ); and a microwave oscillator source 50, connected to the waveguide portion 40A (refer to Figure 1 , Figure 2 ).

[0086] Furthermore, the workpiece W is placed on both the bottom wall and the top wall of the chamber 10A, but the invention is not limited thereto, and the workpiece W may be placed on either the bottom wall or the top wall of the chamber 10A. Description of Reference Numerals

[0087] 1. Microwave plasma CVD device; 10A, chamber; 10B, chamber; 10C, chamber; 10D, chamber; 10E, chamber; 10F, chamber; 10G, chamber; 11. Bottom wall; 12. Side wall; 13. Coaxial opening; 20. Microwave introduction port; 30A, microwave introduction window; 30B, microwave introduction window; 30C, microwave introduction window; 40A, waveguide portion; 40B, waveguide portion; 41. Microwave mode converter; 50. Microwave oscillation source; 60. Raw material gas introduction part; 70. Gas discharge unit; 80A, coaxial structure; 80B, coaxial structure; 80C, coaxial structure; 80D, coaxial structure; 80E, coaxial structure; 80F, coaxial structure; 80G, coaxial structure; 81. Center conductor; 82. External conductor; 90. Circulator; 91. First port; 92. Second port; 93. Third port; 100, EH tuner; 101, E tuner unit; 102, H tuner unit; 110A, loading platform; 110B, loading platform; 110C, loading platform; 110D, loading platform; 110E, loading platform; 110F, loading platform; 110G, loading platform; 411. Waveguide; 411a, one end; 411b, the other end; 412. Resonator; 412A, peripheral side wall; 412B, inner peripheral side wall; 412C, microwave introduction port; 413, coaxial structure; 413A, peripheral side wall; 413B, inner side wall.

Claims

1. A microwave plasma CVD device, wherein: The microwave plasma CVD device comprises: Chamber; A mounting table is provided at the center of the chamber when looking down at the chamber; A raw material gas introduction part, for introducing a raw material gas into the chamber; a gas exhaust portion for exhausting gas from the chamber; a plurality of microwave introduction ports coupled in a manner matching an internal resonant mode of the chamber; One or more microwave introduction windows, isolating the chamber from the waveguide pressure while allowing microwaves to pass through; a waveguide portion connected to the plurality of microwave introduction ports; as well as The microwave oscillation source is connected to the waveguide portion.

2. The microwave plasma CVD device according to claim 1, wherein: The microwave plasma CVD device further includes a coaxial structure, which includes a central conductor located in the center of the chamber when the chamber is viewed from above and parallel to the axial direction of the symmetry axis of the internal resonance mode of the chamber, and an outer conductor located around the central conductor. The plurality of microwave introduction ports are provided in the coaxial structure portion of the chamber.

3. The microwave plasma CVD device according to claim 1 or 2, wherein: An introduction direction of the microwaves introduced from the plurality of microwave introduction ports is parallel to an axial direction of a symmetry axis of the internal resonance mode of the chamber or an axial direction of the central conductor.

4. The microwave plasma CVD device according to claim 2, wherein: The introduction direction of the microwaves introduced from the plurality of microwave introduction ports is perpendicular to the axial direction of the symmetry axis of the internal resonance mode of the chamber or the axial direction of the central conductor.

5. The microwave plasma CVD device according to claim 2, wherein: The opening surfaces of the plurality of microwave introduction ports are arranged around the central conductor in a plan view of the chamber, and are provided in parallel with the axial direction of the central conductor.

6. The microwave plasma CVD device according to claim 2, wherein: The opening surfaces of the plurality of microwave introduction ports are arranged around the central conductor in a plan view of the chamber, and are provided perpendicularly to the axial direction of the central conductor.

7. The microwave plasma CVD device according to claim 1 or 2, wherein: The opening surfaces of the plurality of microwave introduction ports are arranged along the circumferential direction of the chamber with reference to the symmetry axis of the internal resonance mode of the chamber or the central axis of the central conductor when the chamber is viewed from above.

8. The microwave plasma CVD device according to claim 2, wherein: The waveguide portion includes a square-shaped waveguide tube and a ring-shaped resonator coupled to the square-shaped waveguide tube and provided in the coaxial structure portion of the chamber. The annular resonator is coupled to the coaxial structure via the plurality of microwave introduction ports provided in the resonator. The TE mode of the microwaves propagating in the square waveguide is converted into the TEM mode propagating in the coaxial structure via the ring-shaped resonator.

9. A microwave mode converter, wherein: The microwave mode converter includes a square waveguide, a ring-shaped resonator coupled to the waveguide, and a coaxial structure coupled to the resonator. The TE mode of the microwaves propagating in the square waveguide is converted into the TEM mode propagating in the coaxial structure via the ring-shaped resonator.

10. The microwave mode converter according to claim 9, wherein: The resonator has an outer peripheral side wall and an inner peripheral side wall, and has a plurality of microwave introduction ports arranged in a row along the circumferential direction of the inner peripheral side wall.

11. The microwave mode converter according to claim 10, wherein: The opening surfaces of the plurality of microwave introduction ports are provided in parallel with the axial direction of the symmetry axis of the resonator, and are arranged rotationally symmetrically along the circumferential direction of the inner peripheral side wall with reference to the symmetry axis of the resonator.

12. The microwave mode converter according to claim 10 or 11, wherein: The microwave introduction port is a linear or rectangular slit, The slit is arranged corresponding to the resonance mode in the resonator so that its long side is parallel to the magnetic field direction in the slit, and the magnetic field direction formed by the slit in the coaxial structure is the same as the magnetic field direction in the coaxial structure.

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