Silicon electrode plate and silicon ring for plasma processing apparatus, and manufacturing method thereof

Abstract

To provide a silicon electrode plate for a plasma processing apparatus.SOLUTION: A silicon electrode plate for a plasma processing apparatus comprises: a plate central part 31 and a plate peripheral part 32 provided around the central part. The silicon electrode plate includes: a first surface 301 which is circularly formed by one surface 32A of the plate peripheral part 32 and one surface 31A of the plate central part 31 provided with an inlet 111 of a gas flow path 11, arranged flush with each other; a second surface 302 which is circularly formed by the other surface 31B of the plate central part 31, and provided with an outlet 112 of the gas flow path 11; and an annular surface 303 which is annularly formed by the other surface 32B of the plate peripheral part 32, located opposite the first surface 301. In an observation of ten areas of a top surface cross-section of the annular surface 303 under a scanning electron microscope with a field of view of 12.80 μm×9.60 μm, the total number of microcracks with a size of 1.0 μm or more is two or fewer, or the total number of foreign substances with a size of 1.0 μm or more is two or fewer. Furthermore, the average value of the arithmetic mean roughness Ra of the annular surface 303 is 0.40 μm or less.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a silicon electrode plate and a silicon ring for a plasma processing apparatus, and a method for manufacturing the same. [Background technology]

[0002] In plasma processing apparatuses such as plasma etching apparatuses and plasma CVD apparatuses used in semiconductor device manufacturing processes, an upper electrode and a lower electrode connected to a high-frequency power source are arranged opposite each other in a chamber, and a substrate to be processed is placed on the lower electrode.A process gas for generating plasma is passed through through holes formed in the upper electrode toward the substrate to be processed, and a high-frequency voltage is applied between the two electrodes to generate plasma and perform processing such as etching on the substrate to be processed.

[0003] A conventional disk-shaped silicon electrode plate (upper electrode) is placed in a chamber of a plasma processing apparatus with its stepped peripheral area abutting against an electrode support member.

[0004] Patent Document 1 discloses a silicon electrode plate in which the stepped peripheral region is in contact with an electrode support portion. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-85027 Figure 3 Summary of the Invention [Problem to be solved by the invention]

[0006] A conventional method for manufacturing a silicon electrode plate includes a processing step of forming gas through-holes from a first processed surface to a second processed surface in a plate material obtained by slicing a silicon ingot and cutting the peripheral area of ​​the plate-shaped member into a stepped shape to form an annular surface, an etching step of etching the plate material obtained by the processing step with a mixed acid aqueous solution, and a polishing step of polishing the etched first processed surface, etc. The polishing step reduces the roughness Ra of the plasma surface of the silicon electrode plate, thereby suppressing the generation of particles when the silicon electrode plate is used.

[0007] In Patent Document 1, in order to reduce particle generation, the center line surface roughness Ra of the plasma surface of the silicon electrode plate is set to 1 μm or less, and the center line surface roughness Ra of the annular surface that corresponds to the electrode support part is formed to be more than 1 μm to 1.6 μm.

[0008] In plasma processing, it is desirable to further reduce particle generation. This applies not only to silicon electrode plates but also to silicon rings, such as electrode support members, provided in the chamber of a plasma processing apparatus.

[0009] Therefore, the present invention has been created to solve the above-mentioned problems, and an object of the present invention is to provide a silicon electrode plate for a plasma processing apparatus, a silicon ring for a plasma processing apparatus, and methods for manufacturing the same. [Means for solving the problem]

[0010] The present invention provides a silicon electrode plate for a plasma processing apparatus, which is formed in a disk shape and includes a central portion in which a plurality of gas flow paths are formed, and a peripheral portion that is disposed around the central portion and is thinner than the central portion. The silicon electrode plate has a first surface formed in a circle, where one surface of the peripheral portion is flush with one surface of the central portion where the gas flow path inlets are provided, a second surface formed in a circle, which consists of the other surface of the central portion located opposite the first surface and where the gas flow path outlets are provided, and an annular surface formed in a circle, which consists of the other surface of the peripheral portion located opposite the first surface. The annular surface is characterized in that, when observed with a scanning electron microscope at 10 points on the outermost surface cross section of the annular surface within a field of view of 12.80 μm x 9.60 μm, there are a total of two or less microcracks having a size of 1.0 μm or more, or a total of two or less foreign matter having a size of 1.0 μm or more, and the average value of the arithmetic mean roughness Ra of the annular surface is 0.40 μm or less.

[0011] In the above-mentioned silicon electrode plate, preferably, when observed with a scanning electron microscope at 10 locations on the outermost cross section of the annular surface within a field of view of 12.80 μm × 9.60 μm, the total number of microcracks having a size of 1.0 μm or more is 2 or less, and the total number of foreign matter having a size of 1.0 μm or more is 2 or less. The arithmetic mean roughness Ra is measured at multiple locations on the annular surface, for example, at six locations. The annular surface of a silicon electrode plate for a plasma processing device is located in a location that cannot be polished by, for example, contacting a polishing table. The annular surface has low roughness and is formed with few microcracks and few foreign particles, thereby suppressing particle generation caused by cracks or foreign particles on the annular surface. Foreign particles include, for example, cutting oil, cutting chips, and polishing grains.

[0012] The silicon electrode plate of the present invention preferably comprises a first outer peripheral surface connecting the periphery of the first surface and the outer peripheral edge of the annular surface, and a second outer peripheral surface connecting the periphery of the second surface and the inner peripheral edge of the annular surface, wherein at least one of the first outer peripheral surface and the second outer peripheral surface has a total of two or less microcracks or a total of two or less foreign matter when observed with a scanning electron microscope at 10 locations on the outermost surface cross section within a field of view of 12.80 μm × 9.60 μm, and further characterized in that at least one of the first outer peripheral surface and the second outer peripheral surface has an average value of 0.40 μm or less of arithmetic mean roughness Ra.

[0013] In the above-mentioned silicon electrode plate, preferably, when observed with a scanning electron microscope at 10 locations on the outermost cross section of at least one of the first outer peripheral surface and the second outer peripheral surface within a field of view of 12.80 μm x 9.60 μm, the total number of microcracks having a size of 1.0 μm or more is 2 or less, and the total number of foreign matter having a size of 1.0 μm or more is 2 or less. The first outer peripheral surface and the second outer peripheral surface are provided in locations where polishing cannot be performed, like the annular surface, and the roughness of the first outer peripheral surface and the second outer peripheral surface are small, and the number of microcracks on these outer peripheral surfaces is small, thereby making it possible to suppress the generation of particles during plasma processing.

[0014] The silicon electrode plate of the present invention is preferably characterized in that the second surface has an average value of arithmetic mean roughness Ra of 0.40 μm or less.

[0015] The arithmetic mean roughness Ra is measured at a plurality of locations on the second surface, for example, six locations. By forming the second surface with a small roughness, particle generation can be suppressed.

[0016] The present invention provides a silicon ring for use in a plasma processing apparatus, comprising an outer ring portion and an inner ring portion concentrically disposed within the outer ring portion, the outer ring portion and the inner ring portion constituting a first annular surface disposed on an imaginary plane perpendicular to a central axis, the outer ring portion having a second annular surface positioned opposite the first annular surface and formed annularly, the inner ring portion having a third annular surface positioned opposite the first annular surface, the thickness from the first annular surface to the second annular surface being greater than the thickness from the first annular surface to the third annular surface, and the third annular surface having an outer ring portion and an inner ring portion concentrically disposed within the outer ring portion and formed annularly, the third annular surface having an outer ring portion and an inner ring portion concentrically disposed within the outer ring portion and formed annularly, the thickness from the first annular surface to the second annular surface being greater than the thickness from the first annular surface to the third annular surface, the third annular surface having an outer ring portion and an inner ring portion concentrically disposed within the outer ring portion and formed annularly, the third annular surface having an outer ring portion and an inner ring portion concentrically disposed within the outer ring portion and formed annularly, the thickness from the first annular surface to the second annular surface being greater than the thickness from the first annular surface to the third annular surface being greater than the thickness from the first annular surface to the third annular surface, and the third annular surface having an outer ring portion and an inner ring portion concentrically disposed within the outer ring portion and formed annularly, the third annular surface having an outer ring portion and an inner ring portion concentrically disposed within the outer ring portion and formed annularly, the thickness from the first annular surface to the second annular surface being greater than the thickness from the first annular surface to the third annular surface being greater than the thickness from the first annular surface to the third annular surface, the third annular surface having an outer ring portion and an outer ring portion concentrically disposed within the outer

[0017] In the above-mentioned silicon ring, preferably, when observed with a scanning electron microscope at 10 locations on the outermost cross section of the third annular surface within a field of view of 12.80 μm × 9.60 μm, the total number of microcracks having a size of 1.0 μm or more is 2 or less, and the total number of foreign matter having a size of 1.0 μm or more is 2 or less. The arithmetic mean roughness Ra is measured at multiple locations on the third annular surface, for example, at six locations. The third annular surface of the silicon ring for plasma processing equipment is provided in a location where polishing processing cannot be performed, for example, by contacting it with a polishing platen, and the third annular surface has small roughness and is formed with few microcracks, etc., so that the generation of particles due to cracks and foreign matter on the third annular surface during plasma processing can be suppressed.

[0018] The silicon ring of the present invention preferably comprises an inner ring inner peripheral surface connecting the inner peripheral edge of the first annular surface and the inner peripheral edge of the third annular surface, and an outer ring inner peripheral surface connecting the inner peripheral edge of the second annular surface and the outer peripheral edge of the third annular surface, wherein at least one of the inner ring inner peripheral surface and the outer ring inner peripheral surface has a total of two or less microcracks having a size of 1.0 μm or more or a total of two or less foreign matter having a size of 1.0 μm or more, when observed with a scanning electron microscope at 10 locations on the outermost surface cross section within a field of view of 12.80 μm × 9.60 μm, and further wherein at least one of the inner ring inner peripheral surface and the outer ring inner peripheral surface has an average value of 0.40 μm or less of arithmetic mean roughness Ra.

[0019] In the above-mentioned silicon ring, preferably, when observed with a scanning electron microscope at 10 locations on the outermost cross section of at least one of the inner circumferential surface of the inner ring and the inner circumferential surface of the outer ring within a field of view of 12.80 μm × 9.60 μm, the total number of microcracks having a size of 1.0 μm or more is 2 or less, and the total number of foreign matter having a size of 1.0 μm or more is 2 or less. The inner peripheral surface of the inner ring and the inner peripheral surface of the outer ring are located in areas that cannot be polished, like the third annular surface, and the roughness of the inner peripheral surface of the inner ring and the inner peripheral surface of the outer ring is small, and the number of microcracks on these inner peripheral surfaces is small, thereby suppressing particle generation.

[0020] The method for manufacturing a silicon electrode plate for a plasma processing apparatus of the present invention comprises a slicing step of slicing a silicon ingot to form a plate-shaped member, a processing step of forming a plurality of through holes in the plate-shaped member and forming a ring-shaped processed annular surface, and an etching step of immersing the plate-shaped member having the processed annular surface and the through holes in a mixed acid solution of hydrofluoric acid (HF), nitric acid (HNO3), and acetic acid (CH3COOH) to etch the plate-shaped member, wherein the average etching amount of the processed annular surface by the etching step is between 60 μm and 300 μm.

[0021] For example, by etching the annular surface of the processed wafer, which cannot be polished by contacting it with a polishing platen, by etching it by 60 μm or more, preferably by etching it by 120 μm or more, it is possible to substantially remove microcracks or foreign particles of 1 μm or more. Conventional manufacturing methods are thought to be insufficient in treating microcracks and foreign particles on the annular surface of the processed wafer. For example, even when an etching process with an etching depth of about 20 μm is performed, microcracks and foreign particles remain. This results in a significant increase in the amount of particles generated during plasma etching.

[0022] The present invention is a method for manufacturing a silicon ring for a plasma processing apparatus, comprising a slicing step of slicing a silicon ingot to form a plate-shaped member, a processing step of processing the plate-shaped member into a ring plate having a stepped inner peripheral surface, and an etching step of etching the ring plate by immersing it in a mixed acid aqueous solution of hydrofluoric acid (HF), nitric acid (HNO3), and acetic acid (CH3COOH), wherein the average etching amount of the inner peripheral surface by the etching step is 60 μm or more and 300 μm or less.

[0023] For example, by etching the stepped inner peripheral surface, which cannot be polished by contacting it with a polishing platen, to a depth of 60 μm or more, preferably 120 μm or more, microcracks of 1 μm or more and foreign matter of 1 μm or more can be almost completely removed. [Effects of the Invention]

[0024] According to the present invention, the annular surface of the silicon electrode plate and the third annular surface of the silicon ring are formed with fewer microcracks and foreign matter than conventional silicon electrode plates, which reduces the occurrence of abnormal discharge when used in a plasma processing apparatus, allowing for normal plasma processing. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a diagram showing a plasma etching apparatus according to an embodiment of the present invention; [Figure 2]FIG. 2 is a plan view showing a first surface side of a silicon electrode plate according to an embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view of the silicon electrode plate taken along line A1-A1 in FIG. 2. [Figure 4] FIG. 1 shows a scanning electron microscope image. [Figure 5] 1A to 1C are diagrams illustrating a method for manufacturing a silicon electrode plate according to an embodiment of the present invention. [Figure 6] FIG. 6 is a cross-sectional view of a plate-shaped member formed in the processing step of FIG. 5. [Figure 7] 3 is a diagram for explaining how to use the silicon electrode plate of FIG. 2. FIG. [Figure 8] 10A to 10C are diagrams for explaining processing steps in a method for manufacturing a shield ring. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0027] As shown in FIG. 1, a plasma etching apparatus 1 according to an embodiment of the present invention has a silicon electrode plate (hereinafter referred to as the electrode plate) 3 serving as an upper electrode provided at the top of a vacuum chamber 2, and a vertically movable stand 4 serving as a lower electrode provided at the bottom parallel to and spaced from the electrode plate 3.

[0028] The upper electrode plate 3 is supported by an insulator 5 in an insulated state relative to the wall of the vacuum chamber 2, and an electrostatic chuck 6 and a silicon support ring 7 surrounding the electrostatic chuck 6 are provided on the pedestal 4. A wafer (substrate to be processed) 8 is placed on the electrostatic chuck 6 with its peripheral region supported by the support ring 7. An etching gas supply pipe 9 is provided at the top of the vacuum chamber 2. The etching gas sent from this etching gas supply pipe 9 is diffused by a diffusion member 10, then flows through an upstream gas flow path 15 provided in a cooling plate 14 made of aluminum or the like with excellent thermal conductivity and a gas flow path 11 provided in the electrode plate 3, toward the wafer 8, and is discharged to the outside from an exhaust port 12 on the side of the vacuum chamber 2.

[0029] This plasma etching apparatus 1 is provided with a high-frequency power supply 13 that applies a high-frequency voltage between the electrode plate 3 and the stand 4. When etching gas is released into the space S between the electrode plate 3 and the stand 4 and a high-frequency voltage is applied from the high-frequency power supply 13, the etching gas turns into plasma in this space S and impinges on the wafer 8. The surface of the wafer 8 is etched by sputtering, i.e., a physical reaction, caused by this plasma and a chemical reaction of the etching gas.

[0030] Furthermore, in order to perform uniform etching of the wafer 8, the generated plasma is concentrated at the center of the wafer 8 and prevented from diffusing to the periphery, thereby generating uniform plasma between the electrode plate 3 and the wafer 8. In this manner, the plasma generation region 16 is usually surrounded by a silicon shield ring 17.

[0031] (electrode plate 3) 2 and 3, the electrode plate 3 is formed in a disk shape, including a plate central portion 31 in which a plurality of gas flow paths 11 are formed, and a plate peripheral portion 32 provided around the plate central portion 31. In FIG. 2, the position of the dashed line indicating a second outer peripheral surface 305 (described later) corresponds to the position of the boundary between the plate central portion 31 and the plate peripheral portion 32.

[0032] Furthermore, as shown in Figure 3, the electrode plate 3 has a first surface 301 formed in a circular shape by one surface 31A of the plate central portion 31 and one surface 32A of the plate peripheral portion 32 being flush with each other, a second surface 302 formed in a circular shape with a smaller diameter than the first surface 301 and consisting of the other surface 31B of the plate central portion 31 located opposite the first surface 301, and an annular surface 303 formed in a ring shape and consisting of the other surface 32B of the plate peripheral portion 32 located opposite the first surface 301.

[0033] In the electrode plate 3, the peripheral portion 32 of the plate is formed thinner than the central portion 31 of the plate. Specifically, the thickness t12 from the first surface 301 to the annular surface 303 is set to be thinner (t12 < t11) compared to the thickness t11 from the first surface 301 to the second surface 302. Further, the electrode plate 3 includes a first outer peripheral surface 304 connecting the periphery of the first surface 301 and the outer peripheral edge of the annular surface 303, and a second outer peripheral surface 305 rising with respect to the annular surface 303 and connecting the periphery of the second surface 302 and the inner peripheral edge of the annular surface 303. The first outer peripheral surface 304 is formed such that the radius from the central axis C1 passing through the center of the first surface 301 and perpendicular to the first surface 301 is constant, and the second outer peripheral surface 305 is also formed such that the radius from the central axis C1 is constant.

[0034] Thus, in the electrode plate 3, around the second surface 302, the annular surface 303, the first outer peripheral surface 304, and the second outer peripheral surface 305 are arranged, and it is configured in a stepped shape from the periphery of the first surface 301 to the second surface 302. The annular surface 303 of the electrode plate 3 constitutes a stepped surface.

[0035] A plurality of gas flow paths 11 penetrate from the first surface 301 to the second surface 302. The inlet 111 of each gas flow path 11 is provided on the first surface 301, and the outlet 112 of each gas flow path 11 is provided on the second surface 302.

[0036] The inlets 111 and outlets 112 of the gas flow paths 11 are each formed in a circular shape, and further, the diameter φ (diameter) of the inlets 111 and outlets 112 is, for example, 0.3 mm or more and 1.0 mm or less. Each gas flow path 11 extends in a direction perpendicular to the first surface 301 and the second surface 302, that is, parallel to the central axis C1. On the first surface 301, the distance between the centers of the circles forming the inlets 111 is, for example, 4.0 mm or more and 50.0 mm or less. Similarly, the distance between the outlets 112 on the second surface 302 is, for example, 4.0 mm or more and 50.0 mm or less. Note that the number and arrangement of the gas flow paths 11 are not limited to the illustrated example.

[0037] The dimensions of the electrode plate 3 are not limited, but may be, for example, a diameter of the first surface 301 of 150.0 mm to 600.0 mm, a diameter of the second surface 302 of 148.0 mm to 598.0 mm, a thickness t11 of 5.0 mm to 25.0 mm, and a thickness t12 of 2.0 mm to 23.0 mm. The difference w (= r1 - r2) between the radius r1 of the first surface 301 and the radius r2 of the second surface 302 is 1.0 mm to 20.0 mm. The step between the first surface 301 and the annular surface 303, i.e., the difference Δt (= t11 - t12) between the thickness t11 and the thickness t12, is 2.0 mm to 23.0 mm.

[0038] The first surface 301 of the electrode plate 3 is preferably subjected to a mirror finish to improve adhesion and bonding with the cooling plate 14. The degree of mirror finish is, for example, such that the average value of the arithmetic mean roughness Ra is about 0.01 μm, and preferably the average value of the arithmetic mean roughness Ra is 0.02 μm or less, but it is sufficient if the average value of Ra is substantially 0.40 μm or less. The arithmetic mean roughness Ra of the first surface 301 is measured at multiple locations on the first surface 301, for example, six locations.

[0039] The average value of the arithmetic mean roughness Ra of the second surface 302 can be 0.10 μm or more, but like the first surface 301, it may be mirror-finished. The degree of mirror finish is, for example, approximately 0.01 μm, preferably 0.02 μm or less, but essentially, it is sufficient if the average value of Ra is 0.40 μm or less. The average value of the arithmetic mean roughness Ra of the annular surface 303 is 0.40 μm or less, preferably 0.35 μm or less, and more preferably 0.25 μm or less. The average values ​​of the arithmetic mean roughness Ra of the first outer peripheral surface 304 and the second outer peripheral surface 305 are 0.40 μm or less. The arithmetic mean roughness Ra of the second surface 302, the annular surface 303, the first outer peripheral surface 304, and the second outer peripheral surface 305 are measured at multiple locations on each surface, for example, six locations on each surface, similar to the measurement of the arithmetic mean roughness Ra of the first surface 301.

[0040] Furthermore, in the electrode plate 3, the number N1 of microcracks on the annular surface 303 is two or less, preferably one or less, and more preferably zero. The number N2 of foreign matter on the annular surface 303 is two or less, preferably one or less, and more preferably zero. In the observation field of a scanning electron microscope, as shown in Figure 4, when a reference line B1 is set relative to the outermost surface of the sample, a microcrack is defined as a crack having a depth (size) of 1.0 μm or more along a direction B2 perpendicular to the reference line B1. Furthermore, foreign matter refers to cutting oil and cutting chips generated during the manufacturing process of the electrode plate, specifically during the machining process, and polishing abrasive grains generated during the polishing process. Among these, foreign matter refers to a portion that protrudes beyond the reference line B1 and forms a gap between the outermost surface or a space at the protruding portion, which cannot be seen as a cross-section of the outermost surface, or a portion within the microcrack that cannot be seen as a cross-section, but forms a gap between the surface of the microcrack or a space within it, all of which are 1.0 μm or more in size. In Figure 4, a space is formed within the protruding portion of the microcrack, which is considered to be a foreign object. Furthermore, the term "size of 1.0 μm or more" for a foreign object means that, assuming that an imaginary circle is placed in the region of the observation field where a foreign object is considered to be present, the diameter of the largest imaginary circle that fits within the region (the dimension indicated by arrow B3 in the figure) is 1.0 μm or more. Furthermore, when observed with a scanning electron microscope at 10 locations on the outermost cross section of annular surface 303 within a 12.80 μm × 9.60 μm field of view, annular surface 303 has a total of 2 or less microcracks N1 of 1.0 μm or more in size, or a total of 2 or less foreign objects N2 of 1.0 μm or more in size. Preferably, the total number of microcracks N1 of 1.0 μm or more in size is 2 or less, and the total number of foreign objects N2 of 1.0 μm or more in size is 2 or less. Furthermore, in the electrode plate 3, when 10 points on the outermost cross section of the annular surface 303 are observed with a scanning electron microscope in a field of view of 12.80 μm × 9.60 μm, the annular surface 303 more preferably has a total of 1 or less microcracks N1 having a size of 1.0 μm or more, and a total of 1 or less foreign matter N2 having a size of 1.0 μm or more.

[0041] To measure microcracks and foreign particles, a 20 mm square sample was cut from the annular surface 303 of the electrode plate 3 using a precision cutting machine, and the top surface cross section of the sample was observed using a scanning electron microscope. The top surface cross section was observed at 10 locations on the top surface of the sample, with a magnification of 10,000 and a field of view of 12.80 μm vertically and 9.60 μm horizontally. At each observation location, the number n1 of microcracks or larger in size and the number n2 of foreign particles or larger in size were determined. The microcrack measurements n1 at each observation location were then added together to determine the total number N1 of microcracks on the annular surface 303. Similarly, the foreign particle measurements n2 at each observation location were added together to determine the total number N2 of foreign particles on the annular surface 303.

[0042] Furthermore, in the electrode plate 3, when 10 locations on the outermost cross section of at least one of the first outer peripheral surface 304 and the second outer peripheral surface 305 were observed using a scanning electron microscope within a field of view of 12.80 μm x 9.60 μm, at least one of the first outer peripheral surface 304 and the second outer peripheral surface 305 had a total of 2 or less microcracks N1 having a size of 1.0 μm or more, or a total of 2 or less foreign matter N2 having a size of 1.0 μm or more, and preferably, a total of 2 or less microcracks N1 having a size of 1.0 μm or more, and a total of 2 or less foreign matter N2 having a size of 1.0 μm or more. Furthermore, in the electrode plate 3, when 10 locations on the outermost cross section of at least one of the first outer peripheral surface 304 and the second outer peripheral surface 305 are observed using a scanning electron microscope within a field of view of 12.80 μm × 9.60 μm, at least one of the first outer peripheral surface 304 and the second outer peripheral surface 305 more preferably has a total of 1 or less microcracks N1 having a size of 1.0 μm or more, and a total of 1 or less foreign matter N2 having a size of 1.0 μm or more.

[0043] (Electrode plate manufacturing method) As shown in FIG. 5, the method for manufacturing the electrode plate 3 includes a slicing step of slicing a silicon ingot to form a plate-shaped member, a processing step of forming a plurality of through holes in the plate-shaped member and cutting the peripheral region of one side of the plate-shaped member to form an annular processed annular surface, an etching step of immersing the plate-shaped member in an aqueous mixed acid solution to etch it, and a polishing step of polishing the etched plate-shaped member to reduce the average value of the arithmetic mean roughness Ra of the surface to 0.30 μm or less.

[0044] (Slicing process) The slicing process involves cutting a cylindrical silicon ingot (a brittle material ingot) into circular plate-shaped components with a diameter of 200 mm to 600 mm and a thickness of 8 mm to 25 mm using a diamond abrasive band saw or wire saw.

[0045] (Processing process) The processing step forms the plate-like member 300 shown in FIG. 6. The plate-like member 300 includes a central portion 310 of the processing plate and a peripheral portion 320 of the processing plate provided around the central portion 310 of the processing plate. Further, the plate-like member 300 has a first processing surface 301A in which one surface 310A of the central portion 310 of the processing plate and one surface 320A of the peripheral portion 320 of the processing plate are flush and circularly formed, and the other surface 310B of the central portion 310 of the processing plate located opposite to the first processing surface 301A, and a second processing surface 302A formed in a circular shape with a diameter smaller than that of the first processing surface 301A, and the other surface 320B of the peripheral portion 320 of the processing plate located opposite to the first processing surface 301A, and a processing annular surface 303A provided around the second processing surface 302A and formed in an annular shape. In the plate-like member 300, the thickness t22 from the first processing surface 301A to the processing annular surface 303A is set to be thinner (t22 < t21) than the thickness t21 from the first processing surface 301A to the second processing surface 302A. Further, the plate-like member 300 includes a first processing outer peripheral surface 304A connecting the periphery of the first processing surface 301A and the outer peripheral edge of the processing annular surface 303A, and a second processing outer peripheral surface 305A connecting the periphery of the second processing surface 302A and the inner peripheral edge of the processing annular surface 303A. The first processing outer peripheral surface 304A is formed with a constant radius from the central axis C1 passing through the center of the first processing surface 301A and perpendicular to the first processing surface 301A, and the second processing outer peripheral surface 305A is also formed with a constant radius from the central axis C1. Thus, in the plate-like member 300, around the second processing surface 302A, the processing annular surface 303A, the first processing outer peripheral surface 304A, and the second processing outer peripheral surface 305A are arranged, and it is configured in a stepped shape from the periphery of the first processing surface 301A to the second processing surface 302A. In the processing step, a plurality of through holes 11A extending from the first processing surface 301A to the second processing surface 302A are formed in the central portion 310 of the processing plate with a drill.

[0046] (Etching process) In the etching process, the plate-shaped member after the processing process is etched with a mixed acid solution to a depth of 60 μm to 300 μm. If the etching amount is less than 60 μm, microcracks of 1 μm or more formed during the processing process cannot be sufficiently removed. If the etching amount exceeds 300 μm, the surface will be burned by the etching solution and will become contaminated.

[0047] The mixed acid solution is a mixture of hydrofluoric acid (HF), nitric acid (HNO3), and acetic acid (CH3COOH), preferably containing 5% to 30% hydrofluoric acid, 10% to 60% nitric acid, and 5% to 30% acetic acid, with the remainder being pure water. This allows the thickness removed by the etching process to be, for example, 60 μm to 300 μm, preferably 120 μm or more. The etching amount is determined from the results of dimensional measurements before and after etching (the difference between the measurements before and after etching) using, for example, an image measuring device equipped with a non-contact displacement sensor.

[0048] In the etching process, cracks and dents are removed from first machined surface 301A, second machined surface 302A, machined annular surface 303A, first machined outer peripheral surface 304A, and second machined outer peripheral surface 305A, and burrs formed on the inner peripheral surface of through hole 11A are also removed, so that first machined surface 301A, second machined surface 302A, machined annular surface 303A, first machined outer peripheral surface 304A, and second machined outer peripheral surface 305A have an average value of arithmetic mean roughness Ra of, for example, 0.40 μm or less after etching. The arithmetic mean roughness Ra is measured at multiple locations on each surface, for example, six locations on each surface.

[0049] (Polishing process) In the polishing process, the second machined surface 302A that has undergone the etching process is mechanically finished using a polishing device. The polishing device holds a plate-shaped member on a carrier and inserts a finishing slurry between a rotating pad and the surface to be polished to perform the polishing. The finishing slurry consists of finishing abrasive grains and a finishing liquid, and the pH of the finishing slurry is between 7.0 and 9.0. The finishing abrasive grains are made of SiO2, and the finishing liquid can be, for example, pure water, anionic surfactants such as sodium laurate, cationic surfactants such as dodecylamine hydrochloride, nonionic surfactants such as polyethylene glycol mono-4-nonylphenyl ether, or polyhydric alcohols such as glycols. Pure water is preferred. The second machined surface 302A undergoes the polishing process to form the second surface 302 with an arithmetic mean roughness (Ra) of, for example, 0.40 μm or less. The first surface 301 may also be formed so that the average value of the arithmetic mean roughness Ra is, for example, 0.40 μm or less by polishing the first processed surface 301A in a polishing process. The arithmetic mean roughness Ra of each surface is measured at multiple locations, for example, six locations on each surface. The processed annular surface 303A is not polished because it cannot be touched with a rotary pad. After polishing, the surface is cleaned with pure water, for example, by ultrasonic cleaning.

[0050] As described above, second processed surface 302A is formed on second surface 302 through the polishing process, completing electrode plate 3. Electrode plate 3 is supported by shield ring 17 in the chamber of plasma etching apparatus 1.

[0051] As shown in Fig. 7, the shield ring 17 includes an outer ring portion 171 and an inner ring portion 172 that is concentric with the outer ring portion 171 and formed inside the outer ring portion 171. The outer ring portion 171 and the inner ring portion 172 are arranged parallel to an imaginary plane P that is perpendicular to the central axis and form a first annular surface 171A that is formed in an annular shape. The central axis of the shield ring 17 is arranged coaxially with the central axis C1 of the electrode plate 3. In Fig. 7, the imaginary plane P is represented by a two-dot chain line.

[0052] The outer ring portion 171 has a second annular surface 171B that is annularly formed and located opposite the first annular surface 171A. The first annular surface 171A is positioned in the chamber facing the wafer 8 and the lower electrode. The diameter of the inner peripheral edge of the first annular surface 171A is set smaller than the diameter of the inner peripheral edge of the second annular surface 171B. In the illustrated example, the diameters of the outer peripheral edges of the first annular surface 171A and the second annular surface 171B are set the same, and the outer peripheral surface 171C connects the outer peripheral edges of the first annular surface 171A and the second annular surface 171B. The outer ring inner peripheral surface 171D extends from the inner peripheral edge of the second annular surface 171B toward the first annular surface 171A, partway through the thickness from the first annular surface 171A to the second annular surface 171B.

[0053] The inner ring portion 172 has an inner ring inner circumferential surface 172A extending from the inner peripheral edge of the first annular surface 171A to the second annular surface 171B, and a third annular surface 172B formed in an annular shape by connecting the end of the inner ring inner circumferential surface 172A on the second annular surface 171B side and the end of the outer ring inner circumferential surface 171D on the first annular surface 171A side. In the shield ring 17, a thickness t31 from the first annular surface 171A to the second annular surface 171B is set to be thicker than a thickness t32 from the first annular surface 171A to the third annular surface 172B (t32 <t31)。

[0054] In this way, in the shield ring 17, the inner peripheral edge of the first annular surface 171A to the inner peripheral edge of the second annular surface 171B is formed as a stepped inner peripheral surface 173 by the inner ring inner peripheral surface 172A, the third annular surface 172B, and the outer ring inner peripheral surface 171D.

[0055] The inner peripheral surface 173 of the shield ring 17 may be formed by etching to a depth of 60 μm or more and 300 μm or less, similar to the etching process for the annular surface 303 of the electrode plate 3. In this case, the shield ring can be manufactured by a method for manufacturing a silicon ring. The method for manufacturing a silicon ring includes a slicing process for slicing a silicon ingot to form a plate-shaped member, a processing process for processing the plate-shaped member into a ring plate having a stepped processed inner peripheral surface, an etching process for etching the ring plate by immersing it in a mixed acid aqueous solution of hydrofluoric acid (HF), nitric acid (HNO), and acetic acid (CHCOOH), and a polishing process for polishing the etched ring plate.

[0056] 8, the ring plate 57 formed through the machining process includes an outer machined ring portion 571 and an inner machined ring portion 572 that is concentric with the outer machined ring portion 571 and formed inside the outer machined ring portion 571. The outer machined ring portion 571 and the inner machined ring portion 572 are arranged parallel to an imaginary plane P2 that is perpendicular to the central axis C2 and form a first machined annular surface 571A that is formed in an annular shape.

[0057] The outer machined ring portion 571 has a second machined annular surface 571B formed in an annular shape and located opposite the first machined annular surface 571A. An outer machined peripheral surface 571C connects the outer periphery of the first machined annular surface 571A with the outer periphery of the second machined annular surface 571B. An inner machined peripheral surface 571D of the outer machined ring portion 571 extends from the inner periphery of the second machined annular surface 571B toward the first machined annular surface 571A, partway through the thickness from the first machined annular surface 571A to the second machined annular surface 571B. The inner machined ring portion 572 has a machined inner peripheral surface 572A extending from the inner peripheral edge of the first machined annular surface 571A to the second machined annular surface 571B, and a third machined annular surface 572B formed in an annular shape by connecting the end of the machined inner peripheral surface 572A on the second machined annular surface 571B side to the end of the machined inner peripheral surface 571D of the outer machined ring portion 571 on the first machined annular surface 571A side. In the ring plate 57, a thickness t41 from the first machined annular surface 571A to the second machined annular surface 571B is set to be thicker than a thickness t42 from the first machined annular surface 571A to the third machined annular surface 572B (t42 <t41)。

[0058] In this way, a step is formed from the inner peripheral edge of the first annular machining surface 571A to the inner peripheral edge of the second annular machining surface 571B by the inner peripheral machining surface 572A and the third annular machining surface 572B of the inner machining ring part 572 and the inner peripheral machining surface 571D of the outer machining ring part 571. Hereinafter, the portion from the inner peripheral edge of the first annular machining surface 571A to the inner peripheral edge of the second annular machining surface 571B will be referred to as the stepped inner peripheral surface 573. In the polishing process, at least one of the first annular machining surface 571A and the second annular machining surface 571B of the ring plate 57 is polished with a rotary pad with a finishing slurry inserted therebetween, but the stepped inner peripheral surface 573 is not polished because the rotary pad cannot be applied to it.

[0059] Furthermore, when the shield ring 17 is manufactured through an etching process with an etching amount of 60 μm or more and 300 μm or less, when observed with a scanning electron microscope targeting 10 points on the outermost cross section of the third annular surface 172B within a field of view of 12.80 μm x 9.60 μm, the third annular surface 172B has a total of 2 or less microcracks N1 having a size of 1.0 μm or more, or a total of 2 or less foreign matter N2 having a size of 1.0 μm or more, and preferably has a total of 2 or less microcracks N1 having a size of 1.0 μm or more, and a total of 2 or less foreign matter N2 having a size of 1.0 μm or more. Furthermore, in the shield ring 17, when observing 10 points on the outermost cross section of the third annular surface 172B with a scanning electron microscope in a field of view of 12.80 μm x 9.60 μm, the third annular surface 172B more preferably has a total of 1 or less microcracks N1 having a size of 1.0 μm or more, and a total of 1 or less foreign matter N2 having a size of 1.0 μm or more.

[0060] When observed using a scanning electron microscope at 10 locations on the outermost cross section of at least one of the inner ring inner surface 172A and the outer ring inner surface 171D within a field of view of 12.80 μm x 9.60 μm, the total number N1 of microcracks of 1.0 μm or larger was 2 or less, or the total number N2 of foreign matter of 1.0 μm or larger was 2 or less, and preferably, at least one of the inner ring inner surface 172A and the outer ring inner surface 171D has a total number N1 of microcracks of 1.0 μm or larger and a total number N2 of foreign matter of 1.0 μm or larger being 2 or less. Furthermore, in shield ring 17, when 10 locations on the outermost cross section of at least one of inner ring inner surface 172A and outer ring inner surface 171D are observed with a scanning electron microscope within a field of view of 12.80 μm × 9.60 μm, at least one of inner ring inner surface 172A and outer ring inner surface 171D more preferably has a total of 1 or less microcracks N1 having a size of 1.0 μm or more, and a total of 1 or less foreign matter N2 having a size of 1.0 μm or more. The third annular surface 172B, the outer ring inner surface 171D, the inner ring inner surface 172A, and the outer surface 171C, which are manufactured through an etching process using a mixed acid aqueous solution with an etching amount of 60 μm or more and 300 μm or less, have an average value of the arithmetic mean roughness Ra of 0.40 μm or less.

[0061] The following description will be given on the assumption that the third annular surface 172B and the like of the inner ring portion 172 of the shield ring 17 are formed without being etched to a depth of 60 μm or more in the etching process.

[0062] The electrode plate 3 is housed in an interior 174 surrounded by the inner peripheral surface 173 of the shield ring 17. Specifically, the electrode plate 3 is disposed in the interior 174 of the shield ring 17 with its annular surface 303 abutting against the third annular surface 172B of the shield ring 17, its first outer peripheral surface 304 facing the outer ring inner peripheral surface 171D of the shield ring 17, and its second outer peripheral surface 305 facing the inner ring inner peripheral surface 172A of the shield ring 17. The electrode plate 3 is disposed with its first surface 301 in close contact with the cooling plate 14 of the plasma etching apparatus 1. The electrode plate 3 is used with its second surface 302, on which the etching gas outlet 112 is formed, facing the space S where plasma is generated as the plasma surface, and the etching gas flows from the upstream gas flow passage 15 of the cooling plate 14 through the gas flow passage 11 of the electrode plate 3 into the plasma generation region 16.

[0063] In the manufacturing method of the electrode plate 3 of this embodiment, the etching amount in the etching process for the processed annular surface 303A, the first processed outer peripheral surface 304A, and the second processed outer peripheral surface 305A, which are surfaces that cannot be surface finished in the polishing process, is increased from the etching amount (20 μm) using a mixed acid aqueous solution in the conventional manufacturing method of an electrode plate to preferably more than three times as much, 60 μm or more, thereby removing microcracks of 1 μm or larger that are formed in the processing process, and the total number N1 of microcracks on the annular surface 303 can be reduced to 2 or less.

[0064] Furthermore, the etching process can reduce foreign matter on the processed annular surface 303A, the first processed outer peripheral surface 304A, and the second processed outer peripheral surface 305A. On the annular surface 303, the total number of foreign matter N2 can be reduced to 2 or less.

[0065] Because there are few microcracks and foreign matter on annular surface 303, when etching wafer 8 is performed with electrode plate 3 supported by shield ring 17, generation of particles caused by microcracks and foreign matter is suppressed, and plasma processing can be performed suitably without causing abnormal discharge. Furthermore, by reducing the arithmetic mean roughness Ra of second surface 302 facing the plasma, generation of particles by second surface 302 during plasma processing can be reduced.

[0066] Furthermore, when placing the electrode plate 3 in the chamber of the plasma etching apparatus 1, if the third annular surface 172B of the shield ring 17 supporting the electrode plate 3 is etched to a depth of 60 μm or more, similar to the etching process in the manufacturing method of the electrode plate 3, the total number N1 of microcracks on the third annular surface 172B will be 2 or less, the total number N2 of foreign matter will be 2 or less, and the average value of the arithmetic mean roughness Ra will be 0.40 μm or less, thereby further suppressing the generation of particles and allowing plasma processing to be performed suitably without causing abnormal discharge.

[0067] The present invention can be practiced without being limited to the above-described and illustrated examples.

[0068] While a shield ring has been cited as an example of a silicon ring for use in a plasma processing apparatus, the silicon ring may also be a support ring 7 that supports a wafer 8. When manufacturing the silicon ring, etching is performed to a depth of 60 μm or more, preferably 120 μm or more. On the stepped inner peripheral surface of the silicon ring, the total number of microcracks N1 is 2 or less, and the total number of foreign particles N2 is 2 or less. Furthermore, the average value of the arithmetic mean roughness Ra of the inner peripheral surface is 0.40 μm or less. [Example]

[0069] The amount of etching was varied to produce electrode plates with stepped edges, and the average arithmetic mean roughness Ra of the annular surface and the second surface facing the plasma of each electrode plate, as well as the total number of microcracks N1 and foreign matter N2 on the annular surface were calculated. The electrode plates were also evaluated by measuring the number of particles generated in the chamber when each electrode plate was used in plasma processing.

[0070] The manufacturing method for each electrode plate includes a slicing step of slicing a silicon ingot made of either single crystal silicon, polycrystalline silicon, or columnar crystal silicon to form a plate-shaped member; a processing step of forming a plurality of through holes that penetrate from a first processing surface to a second processing surface of the plate-shaped member and cutting the peripheral area on the second processing surface side to form an annular processed annular surface; an etching step of immersing the plate-shaped member in a mixed acid aqueous solution to etch it; and a polishing step of polishing the second processing surface of the etched plate-shaped member.

[0071] (Slicing process) In the slicing process, a cylindrical silicon ingot (a brittle material ingot) was cut into plate-shaped components with a diameter of 425 mm and a thickness of 20 mm using a diamond abrasive band saw or wire saw.

[0072] (Processing process) In the machining process, a peripheral region of one surface of the plate-shaped member is formed into a stepped shape. In addition, in the machining process, a drill is used to form a plurality of through holes 11A extending from a first machined surface 301A to a second machined surface 302A opposite the first machined surface 301A. In this way, the plate-shaped member 300 shown in FIG. 6 is formed.

[0073] (etching process) In the etching process, the plate-shaped member after the processing process is etched with a mixed acid solution. The mixed acid solution contains 10% hydrofluoric acid (HF), 50% nitric acid (HNO3), 15% acetic acid (CH3COOH), and the remainder is pure water. The etching process differs between the electrode plate manufacturing methods. The slicing process, processing process, and polishing process are the same for each electrode plate manufacturing method. Examples 1 to 11 are manufactured through an etching process in which the processed annular surface is etched by an amount of 60 μm or more, while Comparative Examples 1 and 2 are manufactured through an etching process in which the processed annular surface is etched by an amount of 40 μm or less. The etching time is 1 minute or more, and increases depending on the etching amount. Comparative Example 3 is an electrode plate manufactured without the etching process. Furthermore, the electrode plates of Examples 1 to 7, 10, and 11 and Comparative Examples 1 to 3 are made of single-crystal silicon, the electrode plate of Example 8 is made of polycrystalline silicon, and the electrode plate of Example 9 is made of columnar crystal silicon. The etching amount of the processed annular surface is the difference between the measured value m1 of the dimension of the plate-shaped member before and after etching, i.e., after the processing process, and the measured value m2 of the dimension of the plate-shaped member after the etching process but before the polishing process, measured using an image measuring instrument equipped with a non-contact displacement sensor (QVT1-X606L1L-C, manufactured by Mitutoyo Corporation). Note that both measured value m1 and measured value m2 are the average values ​​of measured values ​​at multiple locations on the plate-shaped member (multiple locations to measure the etching amount, i.e., six locations on the processed annular surface).

[0074] (Polishing process) In the polishing process, the second processed surface 302A that has undergone the etching process is mechanically finished using a polishing device. The polishing device holds a plate-shaped member with a carrier, and polishes the surface by placing a finishing slurry between the rotating pad and the surface to be polished. The finishing slurry consists of finishing abrasive grains and a finishing liquid. The finishing slurry is a polishing liquid containing SiO2.

[0075] (Measurement of roughness Ra) The surface roughness of the annular surface was measured using a contact surface roughness meter (SV-3200) manufactured by Mitutoyo Corporation. The arithmetic mean roughness Ra (JIS B0601:2013) was measured at six points on the annular surface using the contact surface roughness meter, and the average of these measurements was calculated. The arithmetic mean roughness Ra of the second surface was also measured at each of the six points on the second surface using the contact surface roughness meter, in the same way as for the annular surface.

[0076] (Measurement of microcracks and foreign particles on the annular surface) A 20 mm square sample was cut from the annular surface of the electrode plate using a precision cutting machine, and the outermost surface cross-section of the sample was observed using a scanning electron microscope. The outermost surface cross-section was observed at 10 locations on the outermost surface of the sample, with a field of view of 12.80 μm x 9.60 μm at a magnification of 10,000 using the scanning electron microscope. At each observation location, the number of microcracks (n1) with a size of 1.0 μm or larger and the number of foreign particles (n2) with a size of 1.0 μm or larger were determined. The microcrack measurements (n1) at each observation location were then added together to obtain the total number of microcracks (N1) on the annular surface. Similarly, the foreign particle measurements (n2) at each observation location were added together to obtain the total number of foreign particles (N2) on the annular surface.

[0077] (Evaluation of particle generation number) As shown in Figure 7, the annular surface 303 of the electrode plate was placed against the third annular surface of the shield ring, with the second outer peripheral surface facing the inner peripheral surface of the inner ring of the shield ring. The first surface of the electrode plate was also tightly attached to the cooling plate. The shield ring was manufactured through an etching process using a mixed acid aqueous solution with an etching depth of 60 μm. A wafer was supported by a support ring and placed opposite the second surface. Under the following conditions, gas was introduced from the upstream gas flow path of the cooling plate through the gas flow path of the electrode plate into the plasma generation region, and plasma was generated by applying a voltage to continuously etch the wafer for 100 hours. The number of particles in the chamber was counted using a particle counter. A grade of "C" was given for particles with 100 or more particles, a grade of "B" for particles with 50 or more particles but less than 100 particles, and a grade of "A" for particles with less than 50 particles. Grades A and B were considered pass. Chamber pressure: 10 -1 Torr Etching gas composition: 90sccm / CHF3+ 4sccm / O2+ 150sccm / He High frequency power: 2kW Vacuum frequency: 20kCycle Note that sccm is an abbreviation for standard cc / min, and refers to the flow rate (cc) per minute normalized at 1 atm (atmospheric pressure 1013 Pa) and a constant temperature such as 0°C or 25°C.

[0078] Table 1 shows the material and etching amount of each electrode plate, the average value of the arithmetic mean roughness Ra of the annular surface and the second surface, the total number N1 and N2 of microcracks and foreign matter on the annular surface, and the evaluation of the number of particles generated.

[0079] [Table 1]

[0080] In Examples 10 and 11, the annular surface that cannot be polished is etched by 60 μm or more but less than 65 μm in the etching process, so that one of the total number of microcracks N1 on the annular surface and the total number of foreign matter N2 is 3, while the other is 1.Furthermore, the average value of the arithmetic mean roughness Ra of the annular surface is 0.38 μm or 0.39 μm, thereby reducing the number of particles generated during plasma processing.

[0081] In Examples 1 to 9, by etching the annular surface that could not be polished by 65 μm or more in the etching process, the average value of the arithmetic mean roughness Ra was 0.40 μm or less, the total number of microcracks N1 on the annular surface after the second surface polishing process was 2 or less, and the total number of foreign particles N2 on the annular surface was 2 or less. This reduced the number of particles generated during plasma processing, allowing for favorable etching of the wafer. Furthermore, when the etching amount was 120 μm or more, the average value of the arithmetic mean roughness Ra on the annular surface was 0.35 μm or less, and both the total number of microcracks N1 and the total number of foreign particles N2 were zero, further reducing particle generation during plasma processing.

[0082] In Comparative Examples 1 and 2, the etching depth of the annular surface that could not be polished was 40 μm or less, the average value of the arithmetic mean roughness Ra was greater than 0.40 μm, the total number of microcracks N1 on the annular surface after the second surface polishing process was 4 or more, and the total number of foreign matter N2 on the annular surface was 3 or more. This resulted in a large number of particles generated during plasma processing. In Comparative Example 3, the total number of microcracks N1, the total number of foreign matter N2, and the number of particles were greater than in Comparative Examples 1 and 2. [Explanation of symbols]

[0083] 1. Plasma etching equipment 3 Electrode plate 31 Center part of board 31A, 32A One side 31B, 32B other side 32 Plate edge 301 Front page 302 Second side 303 Annular Surface 304 First outer peripheral surface 305 Second outer peripheral surface 11 Gas flow path 111 Entrance 112 Exit 17 Shield Ring 171 Outer ring part 172 Inner ring part 171A First Circular Surface 171B Second annular surface 171C Outer surface 171D Inner surface of outer ring 172A Inner ring inner surface 172B Third Circular Surface 173 Inner surface 174 Internal 300 Plate-shaped member 310 Center part of processed plate 310A, 320A One side 310B, 320B other side 320 Processing plate periphery 301A First machined surface 302A Second machining surface 303A Machined Annular Surface 304A First machining outer circumferential surface 305A Second machining outer circumferential surface 11A through hole

Claims

1. A silicon electrode plate for a plasma processing apparatus, which is formed in a disk shape and includes a plate central portion in which a plurality of gas flow paths are formed, and a plate peripheral portion which is provided around the plate central portion and is formed thinner than the plate central portion, a first surface formed in a circular shape by one surface of the plate peripheral portion and one surface of the plate central portion on which the inlet of the gas flow path is provided, the first surface being flush with one another; a second surface formed in a circular shape by the other surface of the plate central portion located opposite the first surface and on which the outlet of the gas flow path is provided; and an annular surface formed in a circular shape by the other surface of the plate peripheral portion located opposite the first surface, When observed with a scanning electron microscope at 10 locations on the outermost cross section of the annular surface within a field of view of 12.80 μm × 9.60 μm, the total number of microcracks having a size of 1.0 μm or more is 2 or less, or the total number of foreign matter having a size of 1.0 μm or more is 2 or less, The silicon electrode plate for a plasma processing apparatus is further characterized in that the average value of the arithmetic mean roughness Ra of the annular surface is 0.40 μm or less.

2. a first outer peripheral surface connecting a peripheral edge of the first surface and an outer peripheral edge of the annular surface, and a second outer peripheral surface connecting a peripheral edge of the second surface and an inner peripheral edge of the annular surface, 2. The silicon electrode plate for a plasma processing apparatus according to claim 1, wherein at least one of the first outer peripheral surface and the second outer peripheral surface has a total of two or less microcracks or a total of two or less foreign matter when observed with a scanning electron microscope at 10 locations on the outermost surface cross section within a field of view of 12.80 μm x 9.60 μm, and further wherein at least one of the first outer peripheral surface and the second outer peripheral surface has an average value of arithmetic mean roughness Ra of 0.40 μm or less.

3. 3. The silicon electrode plate for a plasma processing apparatus according to claim 1, wherein the second surface has an average value of arithmetic mean roughness Ra of 0.40 [mu]m or less.

4. A silicon ring for a plasma processing apparatus, comprising: an outer ring portion; and an inner ring portion that is concentric with the outer ring portion and formed inside the outer ring portion, the outer ring portion and the inner ring portion are arranged parallel to a virtual plane perpendicular to a central axis to form a first annular surface formed in an annular shape, the outer ring portion has a second annular surface positioned opposite the first annular surface and formed in an annular shape; the inner ring portion has a third annular surface that is annularly formed and located opposite the first annular surface, a thickness from the first annular surface to the second annular surface is set to be greater than a thickness from the first annular surface to the third annular surface, When observed with a scanning electron microscope at 10 locations on the outermost cross section of the third annular surface within a field of view of 12.80 μm × 9.60 μm, the total number of microcracks having a size of 1.0 μm or more is 2 or less, or the total number of foreign matter having a size of 1.0 μm or more is 2 or less, The silicon ring for a plasma processing apparatus is further characterized in that the average value of the arithmetic mean roughness Ra of the third annular surface is 0.40 μm or less.

5. an inner ring inner peripheral surface connecting an inner peripheral edge of the first annular surface and an inner peripheral edge of the third annular surface; and an outer ring inner peripheral surface connecting an inner peripheral edge of the second annular surface and an outer peripheral edge of the third annular surface, 5. The silicon ring for a plasma processing apparatus according to claim 4, wherein at least one of the inner ring inner peripheral surface and the outer ring inner peripheral surface has a total of two or less microcracks or a total of two or less foreign matter when observed with a scanning electron microscope at 10 locations on the outermost surface cross section within a field of view of 12.80 μm x 9.60 μm, and further wherein at least one of the inner ring inner peripheral surface and the outer ring inner peripheral surface has an average value of arithmetic mean roughness Ra of 0.40 μm or less.

6. a slicing step of slicing the silicon ingot to form a plate-shaped member; a machining step of forming a plurality of through holes in the plate-like member and forming an annular machined annular surface; The plate-shaped member having the processed annular surface and the through-holes is treated with hydrofluoric acid (HF), nitric acid (HNO ３ ), acetic acid (CH ３ and an etching step of etching the substrate by immersing it in a mixed acid aqueous solution containing a mixed acid such as hydroxybenzoates (HCOOH), 4. A method for manufacturing a silicon electrode plate for a plasma processing apparatus, wherein the etching amount of the processed annular surface in the etching step is 60 μm or more and 300 μm or less.

7. A method for manufacturing a silicon ring for a plasma processing apparatus, comprising: a slicing step of slicing the silicon ingot to form a plate-shaped member; a processing step of processing the plate-shaped member into a ring plate having a stepped inner peripheral surface; The ring plate was treated with hydrofluoric acid (HF), nitric acid (HNO ３ ), acetic acid (CH ３ and an etching step of etching the substrate by immersing it in a mixed acid aqueous solution containing a mixed acid such as hydroxybenzoates (HCOOH), The method for manufacturing a silicon ring for a plasma processing apparatus, wherein the etching amount of the inner peripheral surface in the etching step is 60 μm or more and 300 μm or less.

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