Height adjustment member, heat treatment device and electrostatic chuck device

Abstract

A height adjustment member according to the present disclosure comprises: a base part; and a support part that is positioned on the upper surface of the base part, while having a facing surface that faces a body to be supported. At least the support part contains a ceramic that is mainly composed of silicon carbide, silicon carbonitride or sialon. This height adjustment member has a plurality of closed pores; and the value (C) obtained by subtracting the average (B) of the circle-equivalent diameters of the closed pores from the average (A) of the distances between centroids of two closed pores adjacent to each other is 50 µm to 170 µm.

Description

[Technical Field]

[0001] The present invention relates to a height adjustment member, a heat treatment device, and an electrostatic chuck device. [Background technology]

[0002] Conventionally, heat treatment apparatuses have been used to heat-treat objects to be treated, such as semiconductor wafers and LCD substrates, on a mounting table. Such heat treatment apparatuses are equipped with height adjustment members (plungers and gap pins) for supporting the objects to be treated, as described in Patent Document 1, for example. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-72450 Summary of the Invention

[0004] The height adjustment member according to the present disclosure includes a base and a support portion located on the upper surface of the base and having a surface facing the supported object. At least the support portion includes a ceramic primarily composed of silicon carbide, silicon carbonitride, or sialon. The height adjustment member has a plurality of closed pores, and a value (C) obtained by subtracting the average value (B) of the circle-equivalent diameters of the closed pores from the average value (A) of the distances between the centers of gravity of adjacent closed pores is 50 μm or more and 170 μm or less.

[0005] A heat treatment apparatus according to the present disclosure includes a mounting table and the height adjustment member. The height adjustment member is provided on the mounting table so that the supported object is placed on the mounting table with a gap therebetween.

[0006] The electrostatic chuck device according to the present disclosure includes a mounting table and a focus ring positioned around the mounting table. The focus ring has a fixed portion provided along the circumference and a fixed portion provided concentrically with the fixed portion. Condition The height adjusting member is located on the upper surface of the fixed portion. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a partial cross-sectional view showing a state in which a height adjustment member according to an embodiment of the present disclosure is attached to a support plate; [Figure 2] FIG. 1 is a perspective view illustrating a height adjustment member according to an embodiment of the present disclosure. [Figure 3] FIG. 1 is a side view illustrating a height adjustment member according to an embodiment of the present disclosure. [Figure 4] 1 is a micrograph showing a polished surface obtained by polishing a cross section of a height adjustment member according to an embodiment of the present disclosure. [Figure 5A] 5 is an enlarged micrograph of region X shown in FIG. 4, showing distances x1, x2, and x3 between the centers of gravity of adjacent closed pores. [Figure 5B] 5 is an enlarged micrograph of region X shown in FIG. 4, showing the circle-equivalent diameters d1, d2, and d3 of adjacent closed pores. [Figure 6] 1 is a photomicrograph showing a surface obtained by polishing and etching a cross section of a height adjustment member according to an embodiment of the present disclosure. [Figure 7] FIG. 1 is a cross-sectional view illustrating a heat treatment apparatus according to an embodiment of the present disclosure. [Figure 8] FIG. 8 is an enlarged cross-sectional view of a region Y shown in FIG. 7. [Figure 9] FIG. 1 is a perspective view illustrating a state in which a supported body is placed on a mounting table of an electrostatic chuck device according to an embodiment of the present disclosure. [Figure 10] FIG. 1 is a perspective view illustrating a state in which a supported body is lifted from a mounting table of an electrostatic chuck device according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0008] A height adjustment member according to an embodiment of the present disclosure will be described in detail with reference to Figures 1 to 3. Figure 1 is a partial cross-sectional view showing a height adjustment member 1 according to an embodiment of the present disclosure attached to a support plate 4. Figure 2 is a perspective view showing a height adjustment member 1 according to an embodiment of the present disclosure. The height adjustment member 1 shown in Figure 2 includes a base portion 2 and a support portion 3.

[0009] As shown in FIG. 1, the height adjustment member 1 is a plunger 1a or gap pin 1b attached to a support plate 4 for supporting a supported object W, such as a Si substrate, a SiC substrate, or a GaN substrate, in a processing space. The support plate 4 is disk-shaped and has a heater therein for heating the supported object W. The plunger 1a includes a base 2a and a support portion 3a located on the upper surface of the base 2a and having a facing surface facing the supported object W. The gap pin 1b includes a base 2b and a support portion 3b located on the upper surface of the base 2b and having a facing surface facing the supported object W.

[0010] The plunger 1a can move vertically between a first position P1, which is at the same height as the top surface of the gap pin 1b, and a second position P2, which is higher than the first position P1, by an elastic member 5 such as a spring installed below the plunger 1a. The plunger 1a can support the supported object W at either the first position P1 or the second position P2. By supporting the supported object W at the first position P1, the gap pin 1b is spaced a certain distance from the support plate 4, and even if the temperature of the supported object W is increased by the heater, the temperature variation can be sufficiently suppressed. A plurality of gap pins 1b are fixed to the support plate 4 at predetermined intervals along the circumferential direction, for example, by bonding.

[0011] The support plate 4 has a circumferential groove 6 therein, and a plurality of plungers 1a are installed at predetermined intervals in this groove 6. To prevent the plungers 1a from slipping out of the groove 6, stepped portions 8 for mounting annular sealing members 7 surrounding the base 2a are installed at predetermined intervals along the circumferential direction of the groove 6. The stepped portions 8 have a circular cross section perpendicular to the axial direction and have a diameter larger than the width of the groove 6.

[0012] The plunger 1a has a through hole 1a1 along its axis, which is in communication with the groove 6. The inside of the through hole 1a1 and the groove 6 can be evacuated by an evacuation means such as a vacuum pump via a flow path 9 connected to the groove 6, allowing the supported body W to be adsorbed and fixed.

[0013] Hereinafter, unless otherwise specified, the bases 2a and 2b will be referred to as the base 2, and the support portions 3a and 3b as the support portion 3. The base 2 is a member having a flat plate shape, and the base 2 shown in FIG. 2 has a circular shape when viewed from above. The base 2 is a member for fixing the support portion 3, which will be described later, and is made of, for example, ceramics. There are no particular limitations on the ceramics, and examples include ceramics containing silicon carbide, silicon carbonitride, silicon nitride, or sialon as a main component.

[0014] 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. The components that make up the ceramic can be identified using an X-ray diffractometer (XRD) using CuKα radiation. The content of each component can be determined, for example, using an ICP (Inductively Coupled Plasma) emission spectrometer or an X-ray fluorescence analyzer.

[0015] The size of the base 2 is set appropriately depending on, for example, the size of the device including the height adjustment member 1. When the base 2a has a circular shape in a plan view, the diameter of the base 2a is, for example, 3.5 mm or more and 6.5 mm or less. The height of the base 2a is, for example, 2 mm or more and 4.4 mm or less. When the base 2b has a circular shape in a plan view as shown in FIG. 2, the diameter of the base 2b (D1 in FIG. 3) is, for example, 3.5 mm or more and 6.5 mm or less. The height of the base 2b (H1 in FIG. 3) is, for example, 0.5 mm or more and 1.1 mm or less.

[0016] The support portion 3 is, for example, a cylindrical or columnar member, with the support portion 3a shown in Fig. 1 being cylindrical and the support portion 3b being columnar. The support portion 3 is a member for supporting the supported object W, and is formed from ceramics containing silicon carbide, silicon carbonitride, silicon nitride or sialon as its main component (hereinafter, ceramics containing these components as its main component may be referred to as non-oxide ceramics for convenience).

[0017] If at least the support part 3 is made of non-oxide ceramics, the height adjustment member 1 is less likely to expand and contract, and is less likely to deform, even when used in an environment where heating and cooling are repeated. This is because non-oxide ceramics have a small average linear expansion coefficient. The average linear expansion coefficient of non-oxide ceramics at 40°C to 400°C is, for example, 2 to 4 × 10 -6 / K, and this average linear expansion coefficient can be determined in accordance with, for example, JIS R 1618:2002.

[0018] The support part 3 may be formed of a ceramic having the same main component as the base part 2, or may be formed of a ceramic having a different main component. Usually, the support part 3 and the base part 2 are integrally formed of a ceramic having the same main component.

[0019] The size of the support part 3 is set appropriately depending on, for example, the size of the device including the height adjustment member 1. When the support part 3a has a circular shape in a plan view, the diameter of the support part 3a is, for example, 2 mm or more and 3 mm or less. The height of the support part 3a is, for example, 4.8 mm or more and 7.2 mm or less. 2, in the case of the support portion 3b having a cylindrical shape, the diameter of the support portion 3b (D2 in FIG. 3) is, for example, 2 mm or more and 3 mm or less, and the height of the support portion 3b (H2 in FIG. 3) is, for example, 1.2 mm or more and 1.8 mm or less.

[0020] As shown in FIG. 4, a height adjustment member 1 according to one embodiment has a plurality of closed pores 41. FIG. 4 is a micrograph showing a polished surface obtained by polishing a cross section of a height adjustment member 1 according to one embodiment. FIGS. 5A and 5B are enlarged micrographs of region X in FIG. 4, showing the distances x1, x2, and x3 between the centers of gravity of adjacent closed pores and the circle-equivalent diameters d1, d2, and d3 of adjacent closed pores, respectively. In the height adjustment member 1, the value (C) obtained by subtracting the average value (B) of the circle-equivalent diameters d1, d2, d3 of the closed pores 41a, 41b, 41c, from the average value (A) of the distances x1, x2, and x3 between the centers of gravity of adjacent closed pores 41a, 41b, 41c, is 50 μm or more and 170 μm or less.

[0021] If this value (C) is 50 μm or more, the closed porosity decreases and rigidity improves. As a result, the resulting height adjustment member 1 is less likely to bend. On the other hand, if this value (C) is 170 μm or less, the tendency for heat conduction to be hindered by adjacent closed pores 41 increases. Furthermore, even if microcracks occur, the closed pores 41 make it difficult for the microcracks to propagate. As a result, the thermal shock resistance of the resulting height adjustment member 1 improves.

[0022] The distance between the centers of gravity of the closed pores 41 can be obtained, for example, by the following method: The cross section of the height adjusting member 1 is polished and the polished surface obtained is observed at a magnification of 50 times, and an average range is selected. 2 An image of the area (1.36 mm horizontally and 1.3 mm vertically) is captured with a CCD camera to obtain an observation image. The arithmetic mean roughness Ra of the polished surface is, for example, 0.2 μm or less, and this arithmetic mean roughness Ra may be determined in accordance with JIS B 0601:2013. Using this observation image, the distance between the centers of gravity of the closed pores 41 may be determined by the distance between the centers of gravity method of dispersity measurement, for example, using image analysis software "A-zo-kun (ver. 2.52)" (registered trademark, manufactured by Asahi Kasei Engineering Co., Ltd.). Hereinafter, when the image analysis software "A-zo-kun" is mentioned, it refers to the image analysis software manufactured by Asahi Kasei Engineering Co., Ltd.

[0023] The setting conditions for this method are, for example, a threshold value, which is an index showing the brightness of an image, of 156, brightness is dark, and the area for removing small figures is 20 μm 2 The threshold value can be adjusted according to the brightness of the observed image, the brightness can be darkened, the binarization method can be set to manual, and the small figure removal area can be set to 20 μm 2 The threshold value may be adjusted so that the markers appearing in the observed image match the shape of the closed pores 41, with the noise reduction filter being disabled.

[0024] The circle-equivalent diameter of the closed pores 41 can be obtained by a method called particle analysis using the above-mentioned observation image as the subject. The setting conditions for this method can be the same as those used in the centroid distance method for dispersity measurement.

[0025] The kurtosis Ku of the distance between the centers of gravity of the closed pores 41 may be 0.3 or more and 4 or less. When the kurtosis Ku of the distance between the centers of gravity of the closed pores 41 is 0.3 or more, the variation in the distance between the centers of gravity of the closed pores 41 is reduced (i.e., the distribution of the distance between the centers of gravity of the closed pores 41 is narrowed). As a result, there are fewer areas with locally poor mechanical properties. On the other hand, when the kurtosis Ku of the distance between the centers of gravity of the closed pores 41 is 4 or less, there are no closed pores 41 that are extremely far from each other. As a result, the thermal shock resistance can be further improved.

[0026] Here, kurtosis Ku is an index (statistic) that indicates how much the peak and tail of a distribution differ from a normal distribution. When kurtosis Ku>0, the distribution has a sharp peak and long, thick tails. When kurtosis Ku=0, the distribution is normal. When kurtosis Ku<0, the distribution has a rounded peak and short, thin tails. The kurtosis Ku of the distance between centroids can be calculated using the function Kurt provided in Excel (registered trademark, Microsoft Corporation).

[0027] The non-oxide ceramic may have coarse crystal grains 42 as shown in Figure 6. In this specification, "coarse crystal grains" refers to grains with an area of ​​1000 µm 2This means crystal particles of 6% or more by area. The proportion of the coarse crystal particles 42 is not limited, and for example, the area of ​​the coarse crystal particles 42 may be 6% by area or more and 15% by area or less. When the area of ​​the coarse crystal particles 42 is 6% by area or more, even if fine cracks occur due to thermal shock, the coarse crystal particles 42 can make it difficult for the cracks to propagate. On the other hand, when the area of ​​the coarse crystal particles 42 is 15% by area or less, the mechanical properties (strength, rigidity, fracture toughness, etc.) can be improved.

[0028] The coarse-grained crystal particles 42 may contain intragranular pores 44. When the coarse-grained crystal particles 42 contain intragranular pores 44, the intragranular pores 44 tend to alleviate thermal stresses that occur in the coarse-grained crystal particles 42 in high-temperature environments. As a result, heat resistance is improved. The circle-equivalent diameter of the intragranular pores 44 is, for example, 6 μm or less.

[0029] When determining the area of ​​the coarse-grained crystal grains 42, a surface on which crystal grains of various sizes are observed on average is selected. For example, the polished surface of the ceramic is etched by immersing the ceramic for 20 seconds in a heated and molten solution of sodium hydroxide and potassium nitrate in a 1:1 mass ratio. This etched surface is observed extensively using an optical microscope at 50x magnification, and a surface on which coarse-grained crystal grains 42 and fine-grained crystal grains 43 are present on average is selected. The area of ​​that surface is, for example, 2.7 x 10 -2 μm 2 (The horizontal length is 0.19 μm and the vertical length is 0.14 μm). The average value (D) of the circle-equivalent diameter of the fine crystal particles 43 shown in FIG. 6 is, for example, 8 μm or less. 2 Smaller crystal grains may be present.

[0030] The opposing surface 3c of the support portion 3 has fine crystal particles and open pores. The average circle-equivalent diameter (D) of the fine crystal particles on the opposing surface 3c may be smaller than the average circle-equivalent diameter (E) of the open pores. When the average circle-equivalent diameter (D) of the fine crystal particles is smaller than the average circle-equivalent diameter (E) of the open pores, the fine crystal particles are less likely to fall out of the contours of the open pores. As a result, the supported surface of the supported object W is less likely to be damaged.

[0031] The average circle-equivalent diameter (D) of the fine crystal particles is not limited as long as it is smaller than the average circle-equivalent diameter (E) of the open pores. The difference between the average circle-equivalent diameter (D) of the fine crystal particles and the average circle-equivalent diameter (E) of the open pores may be, for example, 5 μm or more, with the upper limit being 29 μm. In this specification, "fine crystal particles" means crystal particles having an equivalent circle diameter of 8 μm or less.

[0032] The average circle-equivalent diameter (D) of the fine crystal particles is, for example, 1 μm or more and 6 μm or less. The average circle-equivalent diameter (E) of the open pores is, for example, 8 μm or more and 30 μm or less. The circle-equivalent diameter of the fine crystal particles is, for example, 2.7×10 -2 μm 2 The average diameter (D) of the equivalent circle diameter is calculated by analyzing the etched surface using image analysis software (e.g., Win ROOF, manufactured by Mitani Corporation). In the analysis, the threshold value of the equivalent circle diameter is set to 0.21 μm, and particles smaller than 0.21 μm are not included in the calculation of the average equivalent circle diameter (D).

[0033] In one embodiment of the height adjustment member 1, a diamond-like carbon (DLC) film may be located at least on the opposing surface 3c of the support portion 3. DLC is a material intermediate between diamond and graphite. The DLC film may further contain at least one of argon, helium, and hydrogen. In particular, if hydrogen is contained, the DLC film can have improved heat resistance and corrosion resistance. The DLC film may be identified using a Raman spectroscopic analyzer.

[0034] When the height-adjustable member 1 is used in a plasma processing space, if the plasma processing space is located on the opposing surface 3c of the support part 3, and the thermal conductivity of the opposing surface 3c is high, the components placed around the support part 3 will be more likely to expand due to radiant heat from the opposing surface 3c. Plasma processing can generate heat of approximately 200°C to 400°C in the plasma processing space. Because the thermal conductivity of the DLC film is low (for example, the thermal conductivity at 20°C is 1 W / (m·K) or less), even if heat is generated in the plasma processing space, if the DLC film is located on the opposing surface 3c, the radiant heat from the opposing surface 3c will be smaller, making it less likely for the components placed around the support part 3 to expand.

[0035] 2, when the support part 3 has a columnar body, the DLC film may also be located on the side surface 3d of the support part 3. When the DLC film is located on the side surface 3d of the support part 3, the same effect as that described above can be obtained.

[0036] Furthermore, the DLC film located on the opposing surface 3c of the support part 3 may be thicker than the DLC film located on the side surface 3d of the support part 3. With this configuration, the heat-shielding effect of the opposing surface 3c is enhanced. Here, if the support part 3 is cylindrical, the side surface 3d of the support part 3 will be curved. If the support part 3 is prismatic, the side surfaces 3d of the support part 3 will intersect with each other at an intersection line. In either case, the DLC film on the side surface 3d of the support part 3 is more susceptible to internal stress accumulation than the DLC film on the opposing surface 3c. If the DLC film on the side surface 3d of the support part 3 is thinner than the DLC film on the opposing surface 3c, the accumulation of internal stress is suppressed, allowing for long-term use.

[0037] The thickness of the DLC film on the facing surface 3c is, for example, 0.5 μm or more and 3 μm or less. The difference in thickness between the DLC film on the facing surface 3c and the DLC film on the side surface 3d may be, for example, 0.01 μm or more and 0.8 μm or less.

[0038] The DLC film may have a plurality of open pores. When the DLC film has open pores, the value (H) obtained by subtracting the average value (G) of the circle-equivalent diameters of the open pores from the average value (F) of the distances between the centers of gravity of adjacent open pores may be greater than the value (C). When the value (H) is greater than the value (C), the open pores in the DLC film are sparsely scattered. As a result, particles generated from inside the open pores can be reduced.

[0039] As shown in FIG. 2, the base 2 may have an annular flange. In such a configuration, a DLC film may be formed on the annular surface 2c of the flange (base) 2. If a DLC film is formed on the annular surface 2c of the flange 2, the radiant heat of the annular surface 2c is reduced. As a result, the expansion of members disposed around the flange (base) 2 can be reduced.

[0040] The DLC film may also be located on the side surface 2d of the flange 2. When the DLC film is located on the side surface 2d of the flange 2, the same effect as described above can be obtained.

[0041] Furthermore, the DLC film located on the annular surface 2c of the flange 2 may be thicker than the DLC film located on the side surface 2d of the flange 2. This configuration enhances the heat-shielding effect of the annular surface 2c. Here, if the flange 2 is disk-shaped, the side surface 2d of the flange 2 will be curved. If the flange 2 is rectangular, the side surfaces 2d of the flange 2 will intersect with each other at an intersection line. In either case, the DLC film on the side surface 2d of the flange 2 is more susceptible to internal stress accumulation than the DLC film on the annular surface 2c. If the DLC film on the side surface 2d of the flange 2 is thinner than the DLC film on the annular surface 2c, the accumulation of internal stress is suppressed, allowing for long-term use.

[0042] The thickness of the DLC film on the annular surface 2c is, for example, 0.5 μm or more and 3 μm or less. The difference in thickness between the DLC film on the annular surface 2c and the DLC film on the side surface 2d may be, for example, 0.01 μm or more and 0.8 μm or less.

[0043] The method for manufacturing the height adjustment member 1 according to the embodiment is not limited, and for example, it can be manufactured by the following procedure. When the main component of the ceramic forming the height adjustment member 1 is silicon carbide, for example, the average particle size (D 50 The process involves preparing α-type silicon carbide powder having a particle size of 0.5 μm to 2 μm, a sintering aid, a hydrophobic pore-forming agent consisting of resin beads, and a pore dispersant for dispersing the pore-forming agent. These raw materials are then wet-mixed and pulverized using a barrel mill, rotary mill, vibration mill, bead mill, attritor, or the like to form a slurry. A dispersant for dispersing the silicon carbide powder may also be added.

[0044] The sintering aid may be a combination of boron carbide powder and a phenol aqueous solution or a powder of lignin sulfonate and lignin carboxylate as a carbon source, or a combination of aluminum oxide powder and a powder of a rare earth oxide such as yttrium oxide. When the sintering aid is the former combination, for example, the boron carbide powder is 0.2 parts by mass or more and 0.6 parts by mass or less, and the phenol aqueous solution or the powder of lignin sulfonate and lignin carboxylate is 0.5 parts by mass or less in terms of carbon, relative to 100 parts by mass of α-type silicon carbide powder. End 4.0 parts by mass below The salts of the lignin sulfonate and lignin carboxylate may be at least one of lithium, sodium and ammonium.

[0045] The pore-forming agent is, for example, silicone beads and suspension-polymerized crosslinkable resin beads made of at least one of polyacrylic and polystyrene. section To obtain the member, the content of the pore-forming agent is set to 1.2 parts by mass or more and 1.76 parts by mass or less with respect to 100 parts by mass of α-type silicon carbide powder, and the average particle size (D 50 ) may be 36 μm or more and 45 μm or less, particularly 40 μm or more and 45 μm or less. In particular, the content of the pore-forming agent may be 1.2 parts by mass or more and 1.38 parts by mass or less per 100 parts by mass of the α-type silicon carbide powder.

[0046] The particle size of the pore-forming agent is, for example, in the range of 5 μm to 125 μm. For example, the height adjustment agent may be a material having a kurtosis Ku of the distance between the centers of gravity of the open pores of 0.3 to 4. section To obtain the part, the average grain size (D 50 ) is 42.5 μm or more and 44.5 μm or less.

[0047] Pore ​​dispersants are used to disperse the pore-forming agent. Examples of pore dispersants include anionic surfactants such as carboxylates, sulfonates, sulfates, and phosphates. The anionic surfactant adsorbs to the pore-forming agent, allowing the pore-forming agent to easily wet and penetrate into the slurry. Furthermore, the charge repulsion of the hydrophilic groups in the anionic surfactant further suppresses aggregation of the pore-forming agent. Therefore, the pore-forming agent can be sufficiently dispersed in the slurry without aggregation. The anionic surfactant effectively wets and penetrates the pore-forming agent into the slurry. The pore dispersant may be added in an amount of 0.14 to 0.24 parts by mass per 100 parts by mass of the pore-forming agent.

[0048] Next, celluloses such as methyl cellulose and carboxymethyl cellulose or their derivatives are added to this slurry as a binder. sex sugars, starches, dextrins and their various modifications sex Granules are obtained by adding and mixing various water-soluble synthetic resins such as polyvinyl alcohol, synthetic resin emulsions such as vinyl acetate, gum arabic, casein, alginate, glucomannan, glycerin, sorbitan fatty acid esters, etc., and then spray-drying the mixture. Most of the resulting granules contain the pore-forming agent.

[0049] Before spray drying, coarse impurities and dust can be removed by passing the material through a sieve with a mesh size number of 2000 or finer than that specified in ASTM E 11-61. Iron and its compounds can also be removed by using a magnetic iron remover.

[0050] The granules are filled into a mold, and compressed using a uniaxial press or cold isostatic press at a molding pressure of 78 MPa to 128 MPa to obtain a green density of, for example, 1.8 g / cm. 3 More than 1.95g / cm 3 A green body is obtained as the base for the height adjustment member 1, as described below. When the height adjustment member 1 is a plunger 1a, a pilot hole for a through hole may be formed by cutting. This green body is degreased in a nitrogen atmosphere at a temperature of 450 to 650°C for a holding time of 2 to 10 hours to obtain a degreased body. The degreased body is then held in a vacuum atmosphere or a reduced-pressure atmosphere of an inert gas such as argon gas at a temperature of 1800°C to 2200°C for 3 to 5 hours to obtain the height adjustment member 1 made of ceramics whose main component is silicon carbide.

[0051] The height-adjustable member 1 is heat-treated in a high-pressure nitrogen atmosphere at a temperature of 1800°C to 2100°C to obtain a height-adjustable member 1 made of ceramics whose main component is silicon carbonitride. Here, the nitrogen pressure is, for example, 150 MPa to 200 MPa.

[0052] The heat treatment is preferably performed so that the mass of the height adjustment member 1 after the heat treatment increases by 6% to 10% by mass compared to the mass of the height adjustment member 1 before the heat treatment. This is because the generation of silicon nitride increases, resulting in a decrease in thermal conductivity. When the ceramic forming the height adjustment member 1 is mainly composed of silicon nitride, first, silicon nitride powder with a beta conversion rate of 40% or less, powders of calcium oxide, aluminum oxide, and oxides of rare earth elements as sintering aids, a hydrophobic pore-forming agent consisting of resin beads, and a pore dispersing agent for dispersing the pore-forming agent are wet mixed and pulverized using a barrel mill, rotary mill, vibration mill, bead mill, attritor, or the like to form a slurry.

[0053] To obtain ceramics containing sialon as the main component, the above silicon nitride powder is mixed with a β-phase powder having a β-phase ratio of 40% or less and a composition formula of Si 6-Z Al Z O Z N 8-Z(z=0.1 to 1), and a powder of sialon having a solid solution amount z of 0.05 or more and 0.5 or less may be used.

[0054] The total content of the calcium oxide, aluminum oxide, and rare earth element oxide powders should be 3 to 19.2 mass% when the total of the silicon nitride powder and these sintering aid powders is 100 mass%. The calcium oxide and aluminum oxide contents should be 0.3 to 1.5 mass% and 14.2 to 48.8 mass%, respectively, of the sintering aids (100 mass%), with the remainder being the rare earth element oxide. Ferric oxide powder may be added in an amount of 0.02 to 3 mass parts, calculated as Fe, per 100 mass parts of the silicon nitride powder and these sintering aid powders. The ferric oxide powder reacts with the silicon nitride, the main phase, during the firing process described below, releasing oxygen and producing iron silicide.

[0055] There are two types of silicon nitride, α-type and β-type, due to differences in their crystal structures. The α-type is stable at low temperatures, while the β-type is stable at high temperatures. At temperatures above 1400°C, an irreversible phase transition from α-type to β-type occurs. Here, the β-phase ratio is a value calculated using the following formula, where Iα is the sum of the peak intensities of the α(102) diffraction line and the α(210) diffraction line obtained by X-ray diffraction, and Iβ is the sum of the peak intensities of the β(101) diffraction line and the β(210) diffraction line. β conversion rate={Iβ / (Iα+Iβ)}×100 (%)

[0056] The beta phase ratio of silicon nitride powder affects the mechanical strength and fracture toughness (hereinafter, mechanical strength and fracture toughness are referred to as mechanical properties) of ceramics whose main component is silicon nitride. Silicon nitride powder with a beta phase ratio of 40% or less is used because it can improve mechanical properties. Silicon nitride powder with a beta phase ratio of more than 40% acts as a nucleus for grain growth during the firing process, and is prone to forming coarse crystals with a small aspect ratio, which may reduce mechanical properties. Therefore, it is particularly preferable to use silicon nitride powder with a beta phase ratio of 10% or less.

[0057] The β-phase ratio of sialon powder is the same as that described above. If sialon powder with a β-phase ratio of 10% or less is used, the solid solution amount z can be made 0.1 or more. When silicon nitride or sialon powder is pulverized, the particle size (D 90 Grinding the powder until the particle size is 3 μm or less is advantageous in terms of improving sinterability and forming an acicular crystal structure. The particle size distribution obtained by grinding can be adjusted by adjusting the outer diameter of the media, the amount of media, the viscosity of the slurry, the grinding time, etc.

[0058] The support part 3 has a plurality of closed pores, and the value (C) is 50 μm or more and 170 μm or less. section To obtain the member, the content of the pore-forming agent is set to 1.2 parts by mass or more and 1.38 parts by mass or less with respect to 100 parts by mass of silicon nitride or sialon powder, and the average particle size (D 50 ) may be set to 36 μm or more and 45 μm or less, particularly 40 μm or more and 45 μm or less.

[0059] To reduce the viscosity of the slurry, it is advisable to add a dispersant. To grind powders in a short time, the particle size (D 50 It is recommended to use powder with a particle size of 1 μm or less. Formability can be improved by mixing a binder such as paraffin wax, polyvinyl alcohol (PVA), or polyethylene glycol (PEG) into the slurry in an amount of 1 to 10 parts by mass per 100 parts by mass of the total powder. The resulting slurry is passed through a mesh finer than the 200 mesh specified in ASTM E 11-61, and then spray-dried to obtain granules. The granules are filled into a mold, molded, and degreased in the same manner as above to obtain a degreased body.

[0060] Next, the degreased body is placed in a firing furnace equipped with a graphite resistance heating element and fired. Co-materials containing components such as calcium oxide, aluminum oxide, and oxides of rare earth elements may be placed in the firing furnace to suppress volatilization of the components contained in the degreased body. The temperature is raised from room temperature to 300-1000°C in a vacuum atmosphere, and then nitrogen gas is introduced to maintain the nitrogen partial pressure at 50 kPa or higher and 300 kPa or lower. The temperature is then raised to approximately 1400°C or higher to precipitate β-sialon, and the temperature is then raised to 1700°C or higher but lower than 1800°C and maintained for 3 hours to 5 hours, resulting in a height-adjustable ceramic material whose main component is silicon nitride or sialon. section Component 1 is obtained.

[0061] If the compact is placed in a powder mainly composed of silicon nitride or silicon carbide, it can be fired in the air in an electric furnace. By using this method, the compact is buried in the powder mainly composed of silicon nitride or silicon carbide, and oxygen contained in the air is blocked, so that the firing atmosphere is essentially a nitrogen atmosphere.

[0062] While the above-described manufacturing method uses silicon nitride powder, it is also possible to use a method in which the silicon nitride powder is replaced with a powder mixture of silicon powder and silicon nitride powder (hereinafter sometimes referred to as a mixed powder) and reactive sintering is used. Here, the mixed powder is preferably mixed with silicon powder in a mass ratio of 1 to 10 times, particularly 4 to 5.8 times, the silicon nitride powder. When using this mixed powder, a silicon nitriding step is required before firing. This step involves nitriding the silicon in a nitrogen atmosphere at a temperature of 1100°C to 1200°C for a holding time of 6 to 8 hours.

[0063] When using sialon powder, the method described above may be used by replacing the powder with a mixture of silicon powder and sialon powder.

[0064] If necessary, the opposing surface 3c of the support part 3 of the obtained height adjusting member 1 may be subjected to polishing processing. The polishing is carried out by, for example, brush polishing, buff polishing, magnetic fluid polishing, or the like.

[0065] When brush-polishing the opposing surface 3c, the height-adjusting member 1 is fixed, and a roll of brushes about 10 mm long is rotated at 50 rpm to 200 rpm for 30 to 60 minutes. The abrasive used is a paste obtained by adding diamond powder to oils and grease, and this paste is applied to the brush in advance. The average particle size of the diamond powder is, for example, 0.5 μm to 6 μm.

[0066] A DLC film can be formed on the height-adjusting member thus obtained by, for example, plasma ion implantation deposition, which involves superimposing a high-frequency pulse for pulse generation and a negative high-voltage pulse for ion implantation to generate plasma around the support and then drawing ion species in the plasma into the support by the high-voltage pulse.

[0067] Specifically, a 13.56 MHz pulsed high-frequency discharge voltage is first applied to a pre-film-forming height adjustment member placed in a low-pressure hydrocarbon gas atmosphere to generate ion species in hydrocarbon gas plasma. A negative high-voltage pulsed discharge voltage is then applied to the height adjustment member in the afterglow plasma to bombard the height adjustment member with ions, resulting in the formation of a support surface, side surface of the support, annular surface of the base, side surface of the base, and the like, made of a DLC film.

[0068] Before generating the ion species in the hydrocarbon gas plasma, it is advisable to perform a plasma cleaning process using ions of argon, helium, hydrogen, etc. This plasma cleaning process can remove impurities adhering to the support and base, resulting in a DLC film with stronger adhesion to the support and base.

[0069] The height adjustment member 1 according to one embodiment is employed as a component part of various industrial devices, such as a heat treatment device, an electrostatic chuck device, a semiconductor substrate inspection device, a developing device, and the like.

[0070] The heat treatment apparatus includes, for example, a mounting table and a height adjustment member 1 according to one embodiment. The height adjustment member 1 according to one embodiment is provided on the mounting table so that the supported object is placed on the mounting table with a gap therebetween. The heat treatment apparatus will be described in more detail with reference to FIGS. 7 and 8. FIG. 7 is a cross-sectional view showing a heat treatment apparatus according to one embodiment of the present disclosure, and FIG. 8 is an enlarged cross-sectional view of region Y in FIG. 7.

[0071] The heat treatment apparatus 10 has a processing chamber 11 for heat-treating a wafer W. The processing chamber 11 has a mounting table 12 on which the wafer W is placed, lift pins 13 for raising and lowering the wafer W on the mounting table 12, and a shutter 14 for blocking the outside air.

[0072] The shutter 14 is raised or lowered by the operation of a cylinder 15. When the shutter 14 is raised, it comes into contact with a stopper 17 attached to the bottom of the cover 16, and the processing chamber 11 becomes a closed space. An air inlet is provided in the stopper 17, and air that flows into the processing chamber 11 from this air inlet is exhausted from an exhaust port 18 formed in the center of the top of the processing chamber 11. The air that flows in from the air inlet can heat-process the wafer W at a predetermined temperature without directly contacting the wafer W.

[0073] The mounting table 12 is disk-shaped and larger than the wafer W, and has a built-in heater 19 for heating the wafer W. A height adjustment member 1 is provided on the mounting table 12 so that the wafer W is placed on the mounting table 12 with a gap therebetween, thereby suppressing adhesion of particles generated from the mounting surface of the mounting table 12 to the wafer W.

[0074] 8, the height adjustment member 1 includes a base 2 that is attached to a recess 12a provided in the mounting surface of the mounting table 12, and a support 3 that is provided on the upper surface of the base 2 and supports the wafer W. The difference between the heat imparted to the wafer W from the height adjustment member 1 and the heat imparted to the wafer W from the mounting surface of the mounting table 12 is made small.

[0075] Specifically, the holding member 20 is embedded in the space S above the base 2 in the recess 12a to reduce the thermal gradient between the mounting table 12 and the height adjustment member 1. The holding member 20 is preferably made of the same material as the mounting table 12. Other materials may also be used as long as they have similar thermal conductivity to that of the mounting table 12. The gap between the mounting table 12 and the wafer W is, for example, 0.1 mm or more and 0.3 mm or less.

[0076] The lower portions of the lift pins 13 are fixed to a connecting guide 22, which is connected to a timing belt 23. The timing belt 23 is looped around a drive pulley 25 driven by a stepping motor 24 and a driven pulley 26 disposed above the drive pulley 25. By changing the rotation direction of the stepping motor 24, the lift pins 13 are raised or lowered within through-holes 21 provided in the circumferential direction of the mounting table 12, thereby supporting the wafer W at the position indicated by the two-dot chain line or placing the wafer W on the mounting table 12.

[0077] The electrostatic chuck device includes, for example, a mounting table, a focus ring, and a height adjustment member 1 according to one embodiment. The focus ring is located around the mounting table. The focus ring includes a fixed portion provided along the circumference and a movable portion that is concentric with the fixed portion and is displaceable in the up and down direction. The height adjustment member 1 according to one embodiment is provided on an upper surface of the fixed portion. The electrostatic chuck device will be described in more detail with reference to FIGS. 9 and 10.

[0078] Fig. 9 is a perspective view showing a state in which a supported object is placed on a mounting table of an electrostatic chuck device according to an embodiment of the present disclosure, and Fig. 10 is a perspective view showing a state in which the supported object is lifted up from the mounting table of an electrostatic chuck device according to an embodiment of the present disclosure.

[0079] 9 and 10 includes a holder 32 on which a mounting table 31 is mounted. The mounting table 31 has a mounting surface 31a on which a wafer W is mounted.

[0080] The holder 32 is disk-shaped and is disposed on the opposite side from the mounting table 31 (below the electrostatic attraction electrode). The holder 32 cools the mounting table 31 to adjust it to a desired temperature. The holder 32 has a flow path therein for circulating water. The holder 32 is made of, for example, aluminum, aluminum alloy, copper, copper alloy, stainless steel (SUS), titanium, or the like. When the electrostatic chuck device 30 is used in a plasma space, it is preferable that at least the surface of the holder 32 exposed to the plasma be coated with an insulating film such as aluminum oxide.

[0081] 9, focus ring 33 includes an upper ring 34 located on the upper side and a lower ring 35 located below upper ring 34. Upper ring 34 includes a fixed portion 37 provided along the circumference and a movable portion 36 provided concentrically with fixed portion 37 and movable in the up and down direction.

[0082] 10, when the lift pins 38 rise, the movable part 36 rises and lifts the wafer W. The lower surface of the movable part 36 is provided with a positioning hole that fits into the height adjustment member 1 provided on the upper surface of the lower ring 35. Due to the provision of the height adjustment member 1 and the positioning hole, when the movable part 36 descends together with the lift pins 38, the movable part 36 is positioned relative to the lower ring 35. On the other hand, the fixed part 37 is fixed to the lower ring 35.

[0083] The movable part 36 has openings 36b at both ends thereof and is C-shaped in plan view. When the movable part 36 is not moving, the fixed part 37 is located within the openings 36b in plan view. In the electrostatic chuck device 30 shown in FIG. 9, the movable part 36 is in contact with the fixed part 37 at both circumferential ends thereof. In the electrostatic chuck device 30 shown in FIG. 10, the openings 36b of the movable part 36 are open. In the state shown in FIG. 10, a transfer mechanism such as a transfer arm for transferring a wafer W can be inserted into the openings 36b from the radial outside. The movable part 36 has first surfaces 36a at both circumferential ends thereof, each of which is inclined downward.

[0084] The fixed part 37 has second surfaces 37a at both circumferential ends, each of which is inclined upward. In a steady state, the first surface 36a and the second surface 37a overlap each other in the vertical direction due to their respective inclined surfaces. When the first surface 36a and the second surface 37a overlap in this manner, the opposing surfaces of the movable part 36 and the fixed part 37 extend obliquely. When the opposing surfaces extend obliquely, the path along which plasma can penetrate becomes longer, thereby suppressing the penetration of plasma into the gap between the movable part 36 and the fixed part 37.

[0085] Therefore, it is possible to suppress the widening of the gap between the movable part 36 and the fixed part 37 due to plasma erosion, and the electrostatic chuck device 30 can be used for a long period of time. The inclination angle of the first surface 36a and the second surface 37a with respect to the horizontal direction is preferably 45° or less. By setting the inclination angle of the first surface 36a and the second surface 37a within this range, it becomes even more difficult for plasma to penetrate into the gap between the movable part 36 and the fixed part 37.

[0086] The height adjustment member according to the present disclosure is not limited to the above-described embodiment. For example, in the height adjustment member 1 described above, the base 2 has a circular shape when viewed in a plan view. However, the base 2 is not limited to a circular shape. For example, depending on the desired application, the base 2 may have an elliptical shape when viewed in a plan view, or a polygonal shape such as a triangular shape, a rectangular shape, a pentagonal shape, or a hexagonal shape. The support portion 3 is also not limited to a cylindrical shape. For example, depending on the desired application, the support portion 3 may have an elliptical cylindrical shape, a prismatic shape such as a triangular prism, a rectangular prism, a pentagonal prism, or a hexagonal prism, or a shape other than a pillar.

[0087] Furthermore, the above-described method for manufacturing the height adjustment member 1 describes a method for integrally molding the base 2 and the support portion 3. However, the height adjustment member according to the present disclosure may also be manufactured by molding the base 2 and the support portion 3 separately, firing them, and then bonding the base 2 and the support portion 3. The bonding method is not limited, and examples include diffusion bonding.

[0088] Example 1 First, a predetermined amount of a sintering aid and a pore-forming agent were added to the α-type silicon carbide powder, which constitutes the main component. The sintering aid was boron carbide powder and a phenol solution. The pore-forming agent was suspension-polymerized cross-linked resin beads made of polyacrylic styrene.

[0089] In order to obtain the height adjusting member, the content of the pore-forming agent and the average particle size (D 50 ) were as shown in Table 1. Furthermore, sodium polycarboxylate was added as a pore dispersant to each sample in an amount of 0.2 mass% relative to 100 mass% of the pore-forming agent to prepare a blended raw material. This blended raw material was placed in a ball mill for each sample and mixed for 48 hours to form a slurry. A binder was added to this slurry and mixed, followed by spray drying to obtain silicon carbide granules with an average particle size of 80 μm.

[0090] Next, these granules were filled into a mold and pressed in the thickness direction at a pressure of 98 MPa to form a green body. The obtained green body was heated in a nitrogen atmosphere for 20 hours, held at 600°C for 5 hours, and then naturally cooled and degreased to form a degreased body. Next, the degreased body was held in a vacuum atmosphere at 2030°C for 5 hours to obtain disk-shaped and prismatic samples made of ceramics mainly composed of silicon carbide.

[0091] Using each disk-shaped sample, the value (C) obtained by subtracting the average circle-equivalent diameter (B) of the closed pores from the average distance between the centers of gravity of adjacent closed pores (A) was determined using the method described above. Using each prismatic sample, the thermal shock temperature difference was determined using the water immersion method described in JIS R 1648:2002. The dynamic modulus of elasticity of each prismatic sample was determined using the ultrasonic pulse method described in JIS R 1602:1995. The measured values ​​of the value (C), dynamic modulus of elasticity, and thermal shock temperature difference are shown in Table 1.

[0092] [Table 1]

[0093] As shown in Table 1, the values ​​(C) of Samples Nos. 2 to 6 are 50 μm or more and 170 μm or less, which indicates that they have both high rigidity and high thermal shock resistance. [Explanation of symbols]

[0094] 1 Height adjustment member 1a plunger 1b Gap pin 2, 2a, 2b base (flange) 2c Annular surface of flange 2d Side of the flange 3, 3a, 3b Support part 3c Opposite surface 3d side 4 Support Plate 5 Elastic member 6 grooves 7 Sealing member 8 Step 9 style road 1 0 Heat Treatment Equipment 11 Processing Room 12 Mounting table 12a Recess 13 Lift pin 14 Shutter 15 cylinders 16 Cover 17 Stopper 18 Exhaust port 19 Heater 20 Retaining member 21 Through hole 22 Connection guide 23 Timing belt 24 stepping motor 25 Drive pulley 26 Driven pulley 30 Electrostatic chuck device 31 Mounting table 32 Holding part 33 Focus ring 34 Upper ring 35 Lower Ring 36 Moving parts 36a 1st page 36b opening 37 Fixed part 37a 2nd side 38 Lift Pin 41 Closed pores 42 Coarse grained crystal particles 43 Fine crystalline particles 44 Intragranular pores

Claims

1. A base and a support portion located on an upper surface of the base portion and having an opposing surface facing the supported object; Including, At least the support portion includes a ceramic containing silicon carbide, silicon carbonitride, silicon nitride, or sialon as a main component, The porous body has a plurality of closed pores, and a value (C) obtained by subtracting an average value (B) of the equivalent circle diameters of the closed pores from an average value (A) of the distances between the centers of gravity of adjacent closed pores is 50 μm or more and 170 μm or less, the opposing surfaces have fine crystal particles and open pores, and the average circle-equivalent diameter (D) of the fine crystal particles is smaller than the average circle-equivalent diameter (E) of the open pores; Height adjustment member.

2. A base, a support portion located on an upper surface of the base portion and having an opposing surface facing the supported object; Including, At least the support portion includes a ceramic containing silicon carbide, silicon carbonitride, silicon nitride, or sialon as a main component, The porous body has a plurality of closed pores, and a value (C) obtained by subtracting an average value (B) of the equivalent circle diameters of the closed pores from an average value (A) of the distances between the centers of gravity of adjacent closed pores is 50 μm or more and 170 μm or less, The ceramic has coarse crystal grains, and the area of ​​the coarse crystal grains is 6 area % or more and 15 area % or less. Height adjustment member.

3. 3. The height adjusting member according to claim 1, wherein the kurtosis Ku of the distance between the centers of gravity of the closed pores is 0.3 or more and 4 or less.

4. 2. The height adjusting member according to claim 1, wherein the difference between the average circle-equivalent diameter (D) of said fine crystal particles and the average circle-equivalent diameter (E) of said open pores is 5 [mu]m or more.

5. The height adjustment member according to claim 2 , wherein the coarse-grained crystalline particles include intragranular porosity.

6. 3. The height-adjusting member according to claim 1, wherein a DLC film is located on at least the opposing surface.

7. the support portion is a columnar body, and the DLC film is also located on a side surface of the support portion; The height adjustment member according to claim 6 , wherein the DLC film located on the opposing surface is thicker than the DLC film located on a side surface of the support portion.

8. 7. The height-adjusting member according to claim 6, wherein the base has an annular flange, and the DLC film is located on the annular surface of the flange.

9. The DLC film is also located on a side surface of the flange portion, The height adjustment member according to claim 8 , wherein the DLC film located on the annular surface is thicker than the DLC film located on a side surface of the flange portion.

10. 7. The height adjustment member according to claim 6, wherein the DLC film has a plurality of open pores, and a value (H) obtained by subtracting an average value (G) of the circle-equivalent diameters of the open pores from an average value (F) of the distances between the centers of gravity of adjacent open pores is greater than the value (C).

11. A mounting table and the height adjustment member according to claim 1 or 2, the height adjustment member is provided on the mounting table so that the supported object is placed on the mounting table with a gap provided therebetween; Heat treatment equipment.

12. a mounting table and a focus ring positioned around the mounting table, the focus ring includes a fixed portion provided along a circumference thereof and a movable portion provided concentrically with the fixed portion and movable in an up-down direction; The height adjustment member according to claim 1 or 2 is located on the upper surface of the fixing part. Electrostatic chuck device.

13. A base, a support portion located on an upper surface of the base portion and having an opposing surface facing the supported object; Including, At least the support portion includes a ceramic containing silicon carbide, silicon carbonitride, silicon nitride, or sialon as a main component, The porous body has a plurality of closed pores, and a value (C) obtained by subtracting an average value (B) of the equivalent circle diameters of the closed pores from an average value (A) of the distances between the centers of gravity of adjacent closed pores is 50 μm or more and 170 μm or less, A DLC film is located on at least the opposing surface, the DLC film has a plurality of open pores, and a value (H) obtained by subtracting an average value (G) of the circle-equivalent diameters of the open pores from an average value (F) of the distances between the centers of gravity of adjacent open pores is greater than the value (C); Height adjustment member.

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