Ventilated plug and base

Abstract

A vented plug according to the present disclosure includes a first member comprising dense ceramics having a columnar or discoidal shape. A plurality of first through holes penetrating through the first member in the axial direction are located in the outer peripheral region of the first member. The average interval between inner wall surfaces forming adjacent first through holes is greater than the average diameter of the first through holes.

Description

[Technical Field]

[0001] The present invention relates to a breathable plug and a mounting base. [Background technology]

[0002] Conventionally, various members for suppressing discharge that occurs when plasma is generated in semiconductor manufacturing equipment such as plasma etching equipment and plasma CVD (Chemical Vapor Deposition) equipment have been studied. For example, Patent Document 1 describes an electrostatic chuck. This electrostatic chuck has a first porous portion including a plurality of sparse portions having a plurality of holes as breathable plugs and a dense portion having a higher density than the sparse portions.

[0003] However, in conventional breathable plugs such as those described in Patent Document 1, even if an annular dense portion including the outer peripheral surface is provided, the volume occupied by the axially penetrating holes and porous wall portion is relatively large. Therefore, it is not possible to sufficiently increase the mechanical strength. Furthermore, if reaction products generated by plasma penetrate and remain in the pores of the wall portion, the reaction products are difficult to remove. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-165194 Summary of the Invention [Means for solving the problem]

[0005] The breathable plug according to the present disclosure includes a first member made of a dense ceramic having a cylindrical or disc shape. A plurality of first through holes axially penetrating the first member are located in an outer peripheral region of the first member. The average value of the spacing between inner wall surfaces defining adjacent first through holes is greater than the average diameter of the first through holes.

[0006] The mounting table according to the present disclosure is made of a plate-like ceramic having an adsorption surface to which a substrate to be processed is adsorbed and an opposing surface located opposite the adsorption surface, and includes an electrostatic adsorption member having a first flow path along the thickness direction, an internal electrode located within the electrostatic adsorption member, a substrate supporting the electrostatic adsorption member and having a second flow path connected to the first flow path along the thickness direction, and the above-mentioned breathable plug attached inside the first flow path. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a front view of a breathable plug according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a top view seen from the direction of arrow A shown in FIG. [Figure 3] 4 is an explanatory diagram for explaining an outer peripheral region, a middle region, and an inner peripheral region included in the first member. FIG. [Figure 4] FIG. 10 is a top view of a breathable plug according to another embodiment of the present disclosure. [Figure 5] FIG. 10 is a top view of a breathable plug according to yet another embodiment of the present disclosure. [Figure 6] 1 is a cross-sectional view showing a main part of a mounting table according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0008] In conventional breathable plugs such as those described in Patent Document 1, even if an annular dense portion including the outer peripheral surface is provided, the volume occupied by the axially penetrating holes and porous wall portion is relatively large. Therefore, it is not possible to sufficiently increase the mechanical strength. Furthermore, if reaction products generated by plasma penetrate and remain in the pores of the wall portion, they are difficult to remove. Therefore, there is a need for a breathable plug that is highly resistant to arc discharge while maintaining a gas flow rate and that allows the reaction products to be easily removed.

[0009] By virtue of having the above-described configuration, the breathable plug according to the present disclosure has high resistance to arc discharge while maintaining the flow rate of gas, and also allows reaction products to be easily removed.

[0010] A breathable plug according to one embodiment of the present disclosure will be described with reference to Figures 1 to 3. A breathable plug 10 according to one embodiment shown in Figure 1 includes a first member 1 and a second member 2. Figure 1 is a front view showing the breathable plug 10 according to one embodiment.

[0011] The first member 1 is made of dense ceramics. There are no particular restrictions on dense ceramics, and examples include ceramics whose main components are silicon carbide, silicon carbonitride, boron carbide, etc., and ceramics whose main component is aluminum oxide and whose secondary component is at least one titanium compound selected from titanium carbide, titanium carbonitride, and titanium boride. These ceramics are semiconductive, and therefore can gradually release static electricity from the first member 1 made of these ceramics.

[0012] In this specification, "dense ceramics" refers to ceramics with a relative density of 96% or more. The relative density is calculated by (apparent density / theoretical density) x 100. The apparent density is the density of ceramics calculated in accordance with JIS R 1634-1998. Theoretical density is the theoretical density calculated from the components contained in the ceramics.

[0013] In this specification, the term "major component" refers to a component that accounts for 80% by mass or more of the total 100% by mass of the components that make up the ceramic. Each component contained in the ceramic can be identified using an X-ray diffractometer using CuKα radiation, and the content of each component can be determined using, for example, an ICP (Inductively Coupled Plasma) emission spectrometer or an X-ray fluorescence analyzer.

[0014] In this specification, "semiconductive" means a material having a surface resistance of 10 4 Ω or more 10 11The surface resistance value may be measured using, for example, a surface resistance meter (for example, Hioki E.E. Corporation, HiTester 3127-10).

[0015] The first member 1 has a cylindrical or disc shape. The size of the first member 1 is set appropriately depending on the intended use of the resulting breathable plug 10. For example, the height (axial length) of the first member 1 is 30 mm or more and 50 mm or less, and the outer diameter is 0.5 mm or more and 0.8 mm or less.

[0016] As shown in FIG. 2, a plurality of first through holes 11 are formed in the first member 1. FIG. 2 is a top view seen from the direction of arrow A shown in FIG. 1. The first through holes 11 are located in an outer peripheral region 1a of the first member 1 and penetrate the first member 1 in the axial direction. The outer peripheral region 1a of the first member 1 refers to the outer periphery of the first member 1 and a region within 17% of the radius from the outer periphery. Specifically, R1 shown in FIG. 3 is a length that is 17% of the radius, and the region from the outer periphery of the first member 1 to R1 is the outer peripheral region 1a. FIG. 3 is an explanatory diagram for explaining the outer peripheral region 1a, intermediate region 1b, and inner peripheral region 1c included in the first member 1.

[0017] The diameter of the first through holes 11 is not limited and is, for example, 15 μm or more and 50 μm or less. The first through holes 11 are arranged so that the average value of the distance between the inner wall surfaces forming adjacent first through holes 11 is larger than the average value of the diameter of the first through holes 11. The distance between the inner wall surfaces means the distance between the inner wall surfaces on a line connecting the axes of adjacent first through holes 11. Specifically, D1 shown in FIG. 2 corresponds to the distance between the inner wall surfaces. The average value of the distance between the inner wall surfaces is not limited as long as it is larger than the average value of the diameter of the first through holes 11. The average value of the distance between the inner wall surfaces may be, for example, 2 to 3.5 times the average value of the diameter of the first through holes 11.

[0018] As shown in FIG. 2, the first through holes 11 may be positioned at equal intervals on the same circumference. When the first through holes 11 are positioned at equal intervals on the same circumference, the mechanical strength between the first through holes 11 can be made relatively uniform. Here, "on the same circumference" means that the axes of the multiple first through holes 11 are on the same circumference on both end surfaces of the first member 1. However, the circularity of this circumference is allowed to be up to 20% of the average diameter of the first through holes 11. "Equal intervals" means that the central angles between adjacent axes of the first through holes 11 positioned on the same circumference on both end surfaces of the first member 1 are equal. However, in this specification, "equally spaced" means that, when this central angle is θ°, a deviation of θ°±2° is allowed.

[0019] The average value of the shortest distance between each inner wall surface forming the first through holes 11 and the outer wall surface of the first member 1 may be greater than the average value of the diameters of the first through holes 11. Specifically, D2 shown in FIG. 2 corresponds to the above-mentioned shortest distance. When the average value of the shortest distance is greater than the average value of the diameters of the first through holes 11, it is possible to sufficiently maintain mechanical strength near the outer edge in the outer peripheral region 1a. When the first through holes 11 are located on multiple circumferences with different diameters in the outer peripheral region 1a, the above-mentioned average value of the shortest distance refers to the average value of the shortest distance between each inner wall surface forming the first through holes 11 located on the outermost circumference and the outer wall surface of the first member 1.

[0020] The first member 1 is made of dense ceramics, and the first through holes 11 are located in the outer peripheral region 1a of the first member 1. Furthermore, the first through holes 11 are arranged so that the average value of the distance between the inner wall surfaces of adjacent first through holes 11 is greater than the average value of the diameter of the first through holes 11. Therefore, the resulting breathable plug 10 can have improved mechanical properties such as mechanical strength and rigidity. The first through holes 11 are through holes that penetrate the first member 1 in the axial direction. Because the first through holes 11 have a straight cylindrical shape, reaction products adhering to the inner wall surfaces of the first through holes 11 can be easily removed by ultrasonic cleaning or the like. When the diameter of the first through holes 11 is, for example, 15 μm or more, the gas flow rate can be sufficiently maintained. When the diameter of the first through holes 11 is, for example, 50 μm or less, the resistance to arc discharge can be improved.

[0021] In order to maintain a good gas flow rate, it is preferable that the percentage of the total cross-sectional area of ​​the first through holes 11 relative to the cross-sectional area of ​​the first member 1 in a cross section perpendicular to the axial direction be 2% or more. In particular, it is preferable that eight or more first through holes 11 are positioned at equal intervals on the same circumference. The ranges for the same circumference and the equal intervals are as described above.

[0022] 1 and 2, the second member 2 has a larger outer diameter than the first member 1. The outer diameter of the second member 2 is, for example, 0.8 mm or more and 1.2 mm or less, and the difference between the outer diameter of the second member 2 and the outer diameter of the first member 1 is, for example, 0.2 mm or more and 0.5 mm or less. Like the first member 1, the second member 2 also has a cylindrical or disk-like shape and is made of dense ceramics.

[0023] The dense ceramic is not limited to any particular material, and examples thereof include ceramics whose main component is silicon carbide, silicon carbonitride, boron carbide, etc., and ceramics whose main component is aluminum oxide and whose secondary component is at least one titanium compound selected from titanium carbide, titanium carbonitride, and titanium boride. These ceramics are semiconductive, and therefore can gradually release static electricity from the second member 2 formed from these ceramics.

[0024] The second member 2 is connected to the first member 1 on the side where gas is supplied. The end face of the second member 2 on the side where gas is supplied has a smaller average value of the root-mean-square slope (RΔq) of the roughness curve than the end face on the side connected to the first member 1. For example, when the end face of the second member 2 on the side where gas is supplied is in contact with a support member such as a separate breathable plug without being fixed thereto, a small average value of the root-mean-square slope (RΔq) of the end face on the side where gas is supplied can reduce particle shedding originating from the end face of the second member 2 on the side where gas is supplied. On the other hand, when the end face of the second member 2 on the side connected to the first member 1 has a large average value of the root-mean-square slope (RΔq), reaction products floating in the plasma space can be captured at the end face of the first member 1.

[0025] For example, the average value of the root mean square slope (RΔq) of the end face on the gas supply side is 2.6 or less, and the average value of the root mean square slope (RΔq) of the end face on the side connected to the first component 1 is 3.6 or less. The difference between the average value of the root mean square slope (RΔq) of the end face on the gas supply side and the average value of the root mean square slope (RΔq) of the end face on the side connected to the first component 1 is, for example, 0.05 or more and 0.15 or less.

[0026] The root-mean-square slope (RΔq) can be measured in accordance with JIS B 0601-2001 using a shape analysis laser microscope (Keyence Corporation, Ultra-Deep Color 3D Shape Measuring Microscope (VK-X1000 or its successor model)). Measurement conditions are as follows: coaxial illumination, 240x magnification, no cutoff value λs, cutoff value λc of 0.08 mm, end effect correction, and a measurement range of 1428 μm × 1070 μm per location. A circle to be measured is drawn around the periphery of the first through hole 11 within each measurement range, and line roughness measurement is performed. The length of each measurement circle is, for example, 180 μm. At least eight measurement ranges are set on each end face, resulting in a total of eight measurement circles. The average of the measured values ​​obtained for these circles is then calculated.

[0027] When the breathable plug 10 includes a first member 1 and a second member 2, the first through-hole 11 penetrates from the first member 1 to the second member 2.

[0028] Next, a breathable plug according to another embodiment of the present disclosure will be described with reference to Fig. 4. Fig. 4 is a top view showing a breathable plug 10' according to another embodiment of the present disclosure. In Fig. 4, the same members as those in Fig. 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

[0029] In the breathable plug 10 shown in Fig. 2, only a first through hole 11 is located in the outer peripheral region 1a of the first member 1. On the other hand, in the breathable plug 10' shown in Fig. 4, in addition to the first through hole 11, a second through hole 12 is located in the intermediate region 1b of the first member 1. The second through hole 12 also penetrates from the first member 1 to the second member 2.

[0030] As shown in Fig. 3, the intermediate region 1b of the first member 1 refers to the region sandwiched between the outer peripheral region 1a and the inner peripheral region 1c of the first member 1 (the region R2 between R1 and R3 in Fig. 3). The inner peripheral region 1c of the first member 1 refers to a region having a length of 33% of the radius from the axis of the first member 1. Specifically, R3 shown in Fig. 3 is 33% of the radius, and the region surrounded by a circle of radius R3 from the axis is the inner peripheral region 1c.

[0031] The diameter of the second through holes 12 is not limited and is, for example, 15 μm or more and 50 μm or less. The second through holes 12 are arranged so that the average value of the distance between the inner wall surfaces forming adjacent second through holes 12 is larger than the average value of the diameter of the second through holes 12. The distance between the inner wall surfaces is as described above for the first through holes 11, and a detailed description thereof will be omitted. The average value of the distance between the inner wall surfaces is not limited as long as it is larger than the average value of the diameter of the second through holes 12. The average value of the distance between the inner wall surfaces may be, for example, 1.4 times or more and 2 times or less the average value of the diameter of the second through holes 12.

[0032] When the average value of the distance between the inner wall surfaces forming adjacent second through holes 12 is large, it is possible to improve the mechanical properties of the resulting breathable plug 10′, such as the mechanical strength and rigidity between adjacent second through holes 12. Furthermore, when the average value of the diameter of the second through holes 12 is small, the effect of suppressing arc discharge in the resulting breathable plug 10′ is enhanced.

[0033] Similar to the first through holes 11, the second through holes 12 may also be positioned at equal intervals on the same circumference as shown in Fig. 4. When the second through holes 12 are positioned at equal intervals on the same circumference, the mechanical strength between the second through holes 12 can be made relatively uniform. As described above, being positioned on the same circumference and at equal intervals will not be described in detail.

[0034] Next, a breathable plug according to yet another embodiment of the present disclosure will be described with reference to Fig. 5. Fig. 5 is a top view showing a breathable plug 10'' according to yet another embodiment of the present disclosure. In Fig. 5, the same members as those in Figs. 2 and 4 are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0035] In the breathable plug 10 shown in FIG. 2, only a first through hole 11 is located in the outer peripheral region 1a of the first member 1. On the other hand, in the breathable plug 10'' shown in FIG. 5, in addition to the first through hole 11, a second through hole 12 is located in the intermediate region 1b of the first member 1, and a third through hole 13 is located in the inner peripheral region 1c of the first member 1. The third through hole 13 also penetrates from the first member 1 to the second member 2. The inner peripheral region 1c of the first member 1 is as described above.

[0036] The diameter of the third through holes 13 is not limited and is, for example, 15 μm or more and 50 μm or less. The third through holes 13 are arranged so that the average value of the distance between the inner wall surfaces forming adjacent third through holes 13 is larger than the average value of the diameter of the third through holes 13. The distance between the inner wall surfaces is as described above for the first through holes 11, and a detailed description thereof will be omitted. The average value of the distance between the inner wall surfaces is not limited as long as it is larger than the average value of the diameter of the third through holes 13. The average value of the distance between the inner wall surfaces may be, for example, 1.1 to 1.4 times the average value of the diameter of the third through holes 13.

[0037] The first through hole 11, the second through hole 12 and the third through hole 13 may have the same diameter or may have different diameters.

[0038] When the average value of the distance between the inner wall surfaces forming adjacent third through holes 13 is large, the mechanical properties such as the mechanical strength and rigidity between adjacent third through holes 13 can be improved in the resulting breathable plug 10''. Furthermore, when the average value of the diameter of the third through holes 13 is small, the effect of suppressing arc discharge in the resulting breathable plug 10'' is enhanced.

[0039] Similar to the first through holes 11, the third through holes 13 may also be positioned at equal intervals on the same circumference, as shown in Fig. 5. When the third through holes 13 are positioned at equal intervals on the same circumference, the mechanical strength between the third through holes 13 can be made relatively uniform. As being positioned on the same circumference and at equal intervals is as described above, detailed description thereof will be omitted.

[0040] The method for producing the breathable plug according to the present disclosure is not limited, and the breathable plug according to the present disclosure can be obtained, for example, by the following procedure.

[0041] First, powders that will be used as raw materials for dense ceramics are prepared. When the dense ceramics are ceramics whose main component is silicon carbide, coarse-grained powder and fine-grained powder are prepared as silicon carbide powder. Next, ion-exchanged water and a dispersant are added, and the mixture is pulverized and mixed in a ball mill or bead mill for 40 to 60 hours to form a slurry. After pulverization and mixing, the particle size of the fine-grained powder is 0.4 μm to 4 μm, and the particle size of the coarse-grained powder is 11 μm to 34 μm.

[0042] The mass ratio of the fine powder to the coarse powder may be, for example, 6% by mass or more and 15% by mass or less of the fine powder, and 85% by mass or more and 94% by mass or less of the coarse powder. Next, a sintering aid, for example, made of boron carbide powder and amorphous carbon powder or a phenol resin, and a binder are added to the obtained slurry and mixed.

[0043] On the other hand, when the dense ceramic is a ceramic mainly composed of aluminum oxide, the purity is 99.6 mass% or more, and the average particle size (D 50 The powder of aluminum oxide having an average particle size (D) of 1 μm to 3 μm is mixed with a binder, a lubricant, and a solvent. 50 ) can be determined by a laser diffraction particle size distribution measurement method. In addition to aluminum oxide powder, at least one titanium compound selected from titanium carbide, titanium carbonitride, and titanium boride may be contained as a secondary component. The ratio of each powder to a total of 100 mass% of these powders is 50 mass% to 86 mass% aluminum oxide, and the remainder is titanium compound.

[0044] Instead of titanium carbonitride powder, titanium carbide powder and titanium nitride powder may be used. Examples of titanium nitride, carbide, carbonitride, and boride include titanium nitride, titanium carbide, titanium carbonitride, and titanium boride. To promote densification of dense ceramics, 0.06 parts by mass to 0.2 parts by mass of powder of at least one of ytterbium oxide, yttrium oxide, and magnesium oxide may be added.

[0045] Examples of binders include methyl cellulose (MC), carboxymethyl cellulose (CMC), hydroxypropyl cellulose (HPC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB). The total amount of binder may be 2 to 8 parts by mass in solid content per 100 parts by mass of aluminum oxide or silicon carbide powder. When the solid content of the binder is within this range, the fluidity during extrusion molding and the shape retention of the molded body can be improved.

[0046] Examples of lubricants include wax, glycerin, stearic acid, etc. The total amount of lubricant may be 1 to 8 parts by mass in terms of solid content per 100 parts by mass of aluminum oxide or silicon carbide powder.

[0047] The solvent may be water, and ion-exchanged water is particularly preferable because it contains a small amount of impurities. The solvent is added in an amount of, for example, 10 to 20 parts by mass per 100 parts by mass of aluminum oxide or silicon carbide powder so that the viscosity of the clay in the kneading step is 15,000 Pa s to 22,000 Pa s.

[0048] After mixing the raw materials in the above proportions, the mixture is kneaded using a universal mixer, a three-roll mill, or the like to obtain a clay having a viscosity of, for example, 15,000 Pa·s or more and 22,000 Pa·s or less. The viscosity can be measured by a flow property evaluation method using a constant-load extrusion rheometer (Shimadzu Flow Tester CFT-500C, manufactured by Shimadzu Corporation).

[0049] Taking shrinkage due to firing into consideration, this clay is extruded so that the outer diameter after shrinkage becomes the outer diameter of the second member 2, and then dried to remove moisture from the compact. Pilot holes for through holes such as the first through hole 11 may be formed by this extrusion molding. The drying temperature is, for example, 40°C or higher and 70°C or lower. When the main component of the compact is silicon carbide, it is degreased by holding it in a nitrogen atmosphere at a temperature of 450°C or higher and 650°C or lower for 2 hours or higher and 10 hours or lower to obtain a degreased body. Next, this degreased body is fired in a reduced-pressure atmosphere of an inert gas such as argon at a temperature of 1800°C or higher and 2200°C or lower for 0.5 hours or higher and 5 hours or lower to obtain a cylindrical sintered body having through holes such as the first through hole 11.

[0050] On the other hand, when the main component of the compact is aluminum oxide, a cylindrical sintered body having through holes such as the first through hole 11 can be obtained by firing the compact in an air atmosphere at a temperature of 1550°C or higher and 1650°C or lower for 0.5 hours or higher and 5 hours or lower.

[0051] By grinding, polishing, or otherwise processing a portion of the outer periphery of these sintered bodies, the processed portion becomes the first component 1 and the remaining portion becomes the second component 2, thereby obtaining a breathable plug. If this processing is not performed, the entire sintered body becomes the first component 1. Next, the end surface of the second component 2 on the gas supply side is ground, polished, or otherwise processed as necessary so that there is a difference in the average value of the root-mean-square slope (RΔq) of both end surfaces. In this manner, breathable plugs 10, 10', and 10'' are obtained.

[0052] The breathable plug according to the present disclosure is used in an apparatus that generates plasma, such as a plasma etching apparatus, a plasma CVD (Chemical Vapor Deposition) apparatus, etc. Specifically, the breathable plug is a component that constitutes a mounting table provided in such an apparatus.

[0053] FIG. 6 is a cross-sectional view showing the main components of a mounting table according to an embodiment of the present disclosure. The mounting table 20 shown in FIG. 6 includes an electrostatic attraction member 7, an internal electrode 8, a substrate 11a, and a breathable plug 10 according to an embodiment of the present disclosure. The electrostatic attraction member 7 is made of a plate-shaped ceramic having an attraction surface 4 to which a substrate W (e.g., a wafer) is attracted and an opposing surface 5 located opposite the attraction surface 4. The electrostatic attraction member 7 further has a first flow path 6 extending along its thickness. The internal electrode 8 is located within the electrostatic attraction member 7. The substrate 11a has a second flow path 9 extending along its thickness and connected to the first flow path 6. The breathable plug 10 according to an embodiment of the present disclosure is mounted inside the first flow path 6.

[0054] A focus ring 12a is provided on the outer periphery of the electrostatic attraction member 7. The focus ring 12a improves the uniformity of plasma processing on the substrate W to be processed. A sleeve 13a made of ceramics containing aluminum oxide as its main component is attached to the second flow path 9. The sleeve 13a reduces the charge on the substrate 11a and the substrate W to be processed and suppresses abnormal discharge. The substrate 11a is made of a conductive metal, such as aluminum, and functions as a lower electrode.

[0055] The hole diameter of the second flow path 9 is larger than the hole diameter of the first flow path 6. The first flow path 6 opens at the adsorption surface 4. The cooling gas such as helium gas supplied via the second flow path 9 is released from the adsorption surface 4 side of the first flow path 6 and cools the substrate W to be processed.

[0056] The first flow path 6 has a stepped surface, and the hole diameter above the stepped surface is smaller than the hole diameter below the stepped surface. Furthermore, the hole diameter of the second flow path 9 is equal to the hole diameter below the stepped surface of the first flow path 6. For example, the first flow path 6 and the second flow path 9 are approximately aligned in the radial direction at room temperature. The axial length of the breathable plug 10 may be equal to or shorter than the thickness of the electrostatic adsorption member 7.

[0057] Furthermore, a breathable plug 100 may be attached inside the second flow passage 9. The outer diameter of the second member 2 of the breathable plug 10 is smaller than the diameter of the hole below the step portion of the first flow passage 6. The outer diameter of the second member 2 of the breathable plug 100 is smaller than the diameter of the hole of the second flow passage 9. As a result, the breathable plug 10 is disposed with a predetermined gap between it and the inner walls that form the first flow passage 6 and the second flow passage 9, respectively, and the cooling gas flows into this gap and through holes such as the first through hole 11.

[0058] Furthermore, because the breathable plug 10 includes the first member 1 whose outer diameter is smaller than the second member 2, the flow rate of the cooling gas is maintained even if the breathable plug 10 is displaced radially relative to the breathable plug 100. However, if the outer diameter of the first member 1 is made too small compared to the outer diameter of the second member 2, abnormal discharge may occur, so the difference in outer diameter should be 0.5 mm or less.

[0059] In the plasma processing apparatus, the high-frequency power applied to the mounting table 20 is increased in voltage. When the high-frequency power applied to the mounting table 20 is increased in voltage, a potential difference occurs between the substrate to be processed W and the facing surface 5 of the electrostatic attraction member 7 due to the electrostatic capacitance of the electrostatic attraction member 7. If the mounting table 20 does not include the breathable plug 10, the occurrence of this potential difference easily causes the potential difference of the RF potential generated in the first flow path 6 to exceed the limit value at which discharge occurs, and if this limit value is exceeded, abnormal discharge occurs.

[0060] On the other hand, it is known that the occurrence of abnormal discharge can be suppressed by shortening the distance that charged particles of the cooling gas can travel in a straight line inside the first flow path 6. In this embodiment, a breathable plug 10 is installed inside the first flow path 6, thereby making it possible to suppress the occurrence of abnormal discharge.

[0061] The electrostatic attraction member 7 is a plate-shaped member made of ceramic and has an attraction surface 4 to which the substrate W to be processed is attracted and an opposing surface 5 located opposite the attraction surface 4. The base material 11a is a member for supporting the electrostatic attraction member 7. The base material 11a may further have a breathable plug according to the present disclosure attached inside the second flow path 9.

[0062] The breathable plug according to the present disclosure is not limited to the breathable plugs 10, 10', and 10'' described above. For example, the breathable plugs 10, 10', and 10'' described above include a first member 1 and a second member 2. However, the breathable plug according to the present disclosure does not have to include a second member as long as it includes a first member. Depending on the application, the device to be attached, and the like, the breathable plug may include only the first member, or may include both the first member and the second member. [Explanation of symbols]

[0063] 1 First member 11 First through hole 12 Second through hole 13 Third through hole 1a Outer area 1b intermediate area 1c Inner area 2 Second member 4 Adsorption surface 5 Opposite surfaces 6 First flow path 7 Electrostatic attraction material 8 Internal electrode 9 Second flow path 10, 10', 10'', 100 Breathable Plugs 11a Base material 12a Focus ring 13a Sleeve 20 Mounting table

Claims

1. A first member made of dense ceramics having a cylindrical or disc shape, a plurality of first through holes penetrating the first member in the axial direction are located in an outer peripheral region of the first member, and an average value of the intervals between inner wall surfaces defining adjacent first through holes is larger than an average value of the diameters of the first through holes; a second member having a larger outer diameter than the first member; the second member is connected to a side of the first member to which gas is supplied, In the second member, an end face to which the gas is supplied has a smaller average value of a root mean square slope (RΔq) of a roughness curve than an end face to which the first member is connected. Breathable plug.

2. The breathable plug according to claim 1 , wherein the first through-holes are positioned at equal intervals on the same circumference.

3. 3. The breathable plug according to claim 2, wherein an average value of the shortest distance between each inner wall surface forming the first through hole and the outer wall surface of the first member is greater than an average value of the diameter of the first through hole.

4. 2. The breathable plug according to claim 1, wherein the second through holes are located in an intermediate region sandwiched between an outer circumferential region and an inner circumferential region of the first member, and an average value of the intervals between inner wall surfaces forming adjacent second through holes is larger than an average value of diameters of the second through holes.

5. The breathable plug according to claim 4 , wherein the second through-holes are positioned at equal intervals on the same circumference.

6. 2. The breathable plug according to claim 1, wherein the third through holes are located in an inner circumferential region of the first member, and an average value of the intervals between inner wall surfaces forming adjacent third through holes is larger than an average value of diameters of the third through holes.

7. The breathable plug according to claim 6 , wherein the third through-holes are positioned at equal intervals on the same circumference.

8. 2. The breathable plug according to claim 1, wherein the first member is made of ceramics containing silicon carbide, silicon carbonitride, or boron carbide as a main component.

9. 2. The breathable plug according to claim 1, wherein at least one of the first member and the second member is made of a ceramic containing silicon carbide, silicon carbonitride, or boron carbide as a main component.

10. 2. The breathable plug according to claim 1, wherein the first member is made of a ceramic containing aluminum oxide as a main component and at least one titanium compound selected from the group consisting of titanium carbide, titanium carbonitride, and titanium boride as a secondary component.

11. 2. The breathable plug according to claim 1, wherein at least one of the first member and the second member is made of ceramics containing aluminum oxide as a main component and at least one titanium compound selected from titanium carbide, titanium carbonitride, and titanium boride as a secondary component.

12. an electrostatic attraction member made of plate-like ceramic having an attraction surface to which a substrate to be processed is attracted and an opposing surface located opposite the attraction surface, the electrostatic attraction member having a first flow path along a thickness direction; an internal electrode located within the electrostatic attraction member; a substrate supporting the electrostatic attraction member and having a second flow path connected to the first flow path along a thickness direction; and the breathable plug according to any one of claims 1 to 11 attached inside the first flow path. a mounting base including:

13. The mounting table according to claim 12, wherein the breathable plug according to any one of claims 1 to 11 is attached inside the second flow path.

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