Electrode embedding material

Abstract

To provide an electrode embedded material capable of reducing a risk of breakage of corners and joints by relieving stress occurring in corners and joints of supporting members.SOLUTION: An electrode embedded material includes a ceramic base 110 having a substrate body 112 having a substrate mounting surface 114 on its upper surface and formed in a flat plate shape from a ceramic sintered body, and a convex portion 118 integrally formed with the substrate body 112 and protruding from a lower surface 116 of the substrate body opposed to the substrate mounting surface 114 downward, an electrode 130 embedded in the substrate body 112 of the ceramic base 110, and a support member 140 joined to the lower surface 120 of the convex portion facing the substrate mounting surface 114, and in a cross section including a central axis of the ceramic base 110, the cross sections of the lower surface 116 of the base body of the ceramic base 110 and the side surface 122 of the convex portion are formed by a continuous curve, and the curve comprises, an inflection point 124.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electrode-embedding member. [Background technology]

[0002] 2. Description of the Related Art Conventionally, a heater for heating a substrate in a semiconductor manufacturing device has been proposed that integrates a heating and holding member made of a ceramic sintered body with a support member that supports the heating and holding member.

[0003] Patent Document 1 discloses an attachment structure for a susceptor and a support member, which aims to suppress heat transfer from the susceptor into the support member and to alleviate stress concentrated in the support member even when the susceptor is heated to a high temperature. The attachment structure includes a susceptor for heating the workpiece, a support member joined to the susceptor and having an internal space, and a chamber joined to the support member and having an opening, the opening of the chamber being connected to the internal space of the support member, the internal space of the support member being airtightly sealed against the internal space of the chamber, the support member having a cylindrical main body portion and an expanded diameter portion provided at the end of the support member on the susceptor side, and one or multiple continuous curved portions being provided between the main body portion and the expanded diameter portion on the outer contour of the vertical cross section of the support member.

[0004] Patent Document 2 discloses a heating device having a heating base and a support member joined to the heating base, the heating device having a plate-shaped heating base with a heating surface and a hollow cylindrical support member joined to the back surface of the heating base, with the aim of effectively preventing cracks from occurring near the joint between the heating base and the support member. Near the outer end of the joint interface between the heating base and the support member, a concave curved surface portion is formed that smoothly connects the back surface of the heating base and the outer surface of the support member, and the concave curved surface portion is made of ceramics that has an elliptical arc curve whose minor axis direction is parallel to the axial direction of the support member in a cross section including the axis of the support member. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-247745 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-270197 Summary of the Invention [Problem to be solved by the invention]

[0006] The inventors have discovered that, while providing a seat (convex portion) on the underside of a plate, joining a support member to the seat, and simply providing an R-shaped cross section of the seat, as in Patent Document 1 or Patent Document 2, can suppress damage to the joint of the support member to a certain extent, if the corner of the boundary between the plate and the seat and the joint of the support member are close to each other, it may not be sufficient to prevent damage to the corner or joint due to stress concentrated unevenly on one side of the corner or joint of the seat provided on the underside of the plate, or to prevent leaks due to poor airtightness, and that this effect becomes more pronounced when used in processes at higher temperatures than conventional processes.

[0007] Through extensive research, the inventors discovered that by making the cross-sectional shape from the underside of the plate to the side of the seat into a predetermined shape, not only the stress generated at the joint of the support member but also the stress generated at the corners of the boundary between the plate and the seat can be alleviated, leading to the completion of this invention.

[0008] The present invention has been made in consideration of these circumstances, and aims to provide an electrode-embedding member that can alleviate stress occurring at corners and at joints of support members, thereby reducing the risk of damage to corners and joints and the risk of poor airtightness. [Means for solving the problem]

[0009] (1) In order to achieve the above object, the electrode embedding member of the present invention is an electrode embedding member comprising: a ceramic base having a substrate mounting surface on its upper surface and a substrate main body formed in a flat plate shape from a ceramic sintered body; and a convex portion protruding downward from a lower surface of the substrate main body facing the substrate mounting surface and formed integrally with the substrate main body; an electrode embedded in the substrate main body of the ceramic base; and a support member joined to the lower surface of the convex portion facing the substrate mounting surface, wherein in a cross section including the central axis of the ceramic base, the cross sections of the lower surface of the substrate main body of the ceramic base and the side surface of the convex portion are formed by a continuous curve, and the curve has an inflection point.

[0010] In this way, the cross sections of the underside of the base body and the side of the protrusion are formed by continuous curves, and the curves have inflection points, which allows the corners of the boundary between the base body and the protrusion and the joints of the support members to be spaced apart, thereby mitigating stresses generated at the corners and the joints of the support members, thereby reducing the risk of damage to the corners and joints and the risk of poor airtightness.

[0011] Furthermore, the electrode-embedding member of the present invention is characterized in that, when the diameter of the boundary between the convex portion and the substrate main body is Ds1 and the diameter of the lower surface of the convex portion is Ds2, 1.1≦Ds1 / Ds2≦1.5 is satisfied throughout the entire convex portion having the inflection point.

[0012] When the diameter of the boundary between the convex portion and the substrate body is Ds1 and the diameter of the underside of the convex portion is Ds2, by setting Ds1 / Ds2 within a predetermined range throughout the entire convex portion having the inflection point, the stress generated at the corners and the joints of the support member can be further alleviated.

[0013] (2) To achieve the above object, the present invention provides an electrode-embedding member, comprising: a ceramic substrate having a substrate-mounting surface on its upper surface and a flat substrate body made of a sintered ceramic; a protrusion projecting downward from a lower surface of the substrate body opposite the substrate-mounting surface and integrally formed with the substrate body; an electrode embedded in the substrate body of the ceramic substrate; and a support member joined to the lower surface of the protrusion opposite the substrate-mounting surface, wherein, in a cross section including the central axis of the ceramic substrate, the lower surface of the substrate body and the side surface of the protrusion are formed by a continuous curve, and the curve has an inflection point. Furthermore, the present invention is characterized in that, where Ds1 is the diameter of the boundary between the protrusion and the substrate body, Ds2 is the diameter of the lower surface of the protrusion, and T is the thickness of the protrusion, the relationship (Ds1 - Ds2) / 2 ≧ T is satisfied.

[0014] In this way, By specifying the relationship between (Ds1-Ds2) / 2 and T, the difference between the diameter of the boundary between one of the convex portions and the substrate body and the diameter of the lower surface of the convex portion can be made larger than the thickness of the convex portion, and the corners and joints can be spaced farther apart, thereby further alleviating the stress occurring in the corners and joints.

[0015] (3) In addition, in the electrode-embedding member of the present invention, The curve has two or more inflection points. It is characterized by the following.

[0016] In this way, By making the cross-sectional curve a curve with two or more inflection points, the shape of the bottom surface of the base body and the side surface of the convex portion can be varied, which reduces stress at the corners and also at the joints of the support member.It can also accommodate thicker convex portions. [Effects of the Invention]

[0017] According to the present invention, the stress generated at the corners of the boundary between the substrate body and the convex portion is alleviated, and the stress generated at the joint of the support member is also alleviated, thereby reducing the risk of damage to the corners and joints and the risk of poor airtightness. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 2 is a cross-sectional view showing an example of an electrode-embedded member according to the embodiment. [Figure 2] FIG. 2 is a partial cross-sectional view of the electrode-embedding member of FIG. [Figure 3] FIG. 10 is a cross-sectional view showing a modified example of an electrode-embedded member according to the embodiment. [Figure 4] FIG. 4 is a partial cross-sectional view of the electrode-embedded member of FIG. 3. [Figure 5] 1 is a table showing shape characteristics and measurement results of examples and comparative examples. DETAILED DESCRIPTION OF THE INVENTION

[0019] Next, an embodiment of the present invention will be described with reference to the drawings. To facilitate understanding of the description, the same reference numerals are used to designate the same components in the drawings, and duplicated descriptions will be omitted. Note that in the configuration diagrams, the size of each component is shown conceptually and does not necessarily represent the actual dimensional ratio.

[0020] [Embodiment] [Configuration of electrode embedding material] First, the configuration of an electrode-embedded member according to this embodiment will be described. FIG. 1 is a schematic cross-sectional view showing an example of an electrode-embedded member according to this embodiment. FIG. 2 is a partial cross-sectional view of the electrode-embedded member of FIG. 1. An electrode-embedded member 100 according to this embodiment includes a ceramic substrate 110, an electrode 130, and a support member 140. The electrode-embedded member 100 is applied to heaters with shafts, etc.

[0021] The ceramic substrate 110 has a substrate body 112 formed into a flat plate by sintering ceramics, and a protrusion 118 formed integrally with the substrate body 112 and protruding downward from a lower surface 116 of the substrate body facing a substrate mounting surface 114. Here, "protrusion formed integrally with the substrate body" means that the substrate body 112 and the protrusion 118 are not joined with a bonding material. The substrate mounting surface 114 of the ceramic substrate 110 can have various shapes, such as a disk, a polygonal shape, or an ellipse. Materials used for the ceramic sintering body include silicon carbide, aluminum oxide, aluminum nitride, and silicon nitride.

[0022] In the cross section of the ceramic substrate 110 including the central axis, the cross sections of the lower surface 116 of the substrate body and the side surface 122 of the convex portion of the ceramic substrate 110 are formed by a continuous curve. This curve also has an inflection point 124. Since the cross sections of the lower surface 116 of the substrate body and the side surface 122 of the convex portion are formed by a continuous curve and this curve has an inflection point 124, the corner 128 of the boundary 126 between the substrate body 112 and the convex portion 118 and the end of the joint 142 of the support member 140 can be spaced apart to a certain extent, thereby alleviating stresses generated in the corner 128 and the joint 142 of the support member 140. As a result, the risk of damage to the corner 128 and the joint 142 and the risk of poor airtightness can be reduced. The tangent direction of the inflection point 124 in the cross section can be various directions, not just vertical or horizontal.

[0023] The cross section of the lower surface 116 of the substrate body and the side surface 122 of the convex portion being formed by a continuous curve means that there is no singular point in the middle of the cross-sectional curve from the lower surface 116 of the substrate body to the side surface 122 of the convex portion. In this specification, a singular point refers to a corner or edge corresponding to an R of 0.5 (mm) or less or a C of 0.5 (mm) or less in a cross section including the central axis of the ceramic substrate 110. This is because such corners or edges are prone to stress and heat flow concentration, making them prone to becoming the starting point for damage such as cracks. Furthermore, this effect becomes more pronounced when used in processes at higher temperatures than conventional processes.

[0024] Furthermore, the cross section of the lower surface 116 of the base body and the side surface 122 of the convex portion being formed by a continuous curve can be rephrased as meaning that the lower surface 116 of the base body and the side surface 122 of the convex portion are smoothly connected. The continuous curve may include a straight line. The continuous curve may also have a shape in which an inflection point is included in the straight line. It is preferable that the continuous curve does not include a corner or angle equivalent to R3 (mm) or less or C3 (mm) or less.

[0025] The electrode 130 is embedded in the substrate body 112 of the ceramic substrate 110. The electrode 130 may have various shapes, such as a mesh shape or a foil shape, and may be made of various materials, such as molybdenum or tungsten.

[0026] The support member 140 is bonded to the lower surface 120 of the convex portion facing the substrate mounting surface 114. The support member 140 is made of a ceramic sintered body and supports the ceramic base 110. The ceramic sintered body forming the support member 140 preferably contains the same type of ceramic as the ceramic sintered body forming the ceramic base 110 as its main component. In this case, the presence or absence of a sintering aid and the amount of the sintering aid may be different.

[0027] When the diameter of boundary 126 of the protrusion with the base material main body is Ds1 and the diameter of lower surface 120 of the protrusion is Ds2, it is preferable that 1.1≦Ds1 / Ds2≦1.5. In this way, when the diameter of boundary 126 of the protrusion with the base material main body is Ds1 and the diameter of lower surface 120 of the protrusion is Ds2, by setting Ds1 / Ds2 within a predetermined range, stress generated in corner portion 128 and joint portion 142 of support member 140 can be further alleviated.

[0028] When the diameter of boundary 126 of the protrusion with the base material main body is Ds1, the diameter of lower surface 120 of the protrusion is Ds2, and the thickness of protrusion 118 is T, it is preferable that (Ds1-Ds2) / 2 ≥ T. By specifying the relationship between (Ds1-Ds2) / 2 and T in this way, the difference between the diameter of the boundary of one side of protrusion 118 with base material main body 112 and the diameter of lower surface 120 of the protrusion can be made larger than the thickness of protrusion 118, and corner 128 and joint 142 can be sufficiently separated, thereby further alleviating stress generated in corner 128 and joint 142.

[0029] If the corner 128 and the joint 142 are spaced too far apart, the effect of balancedly alleviating the stress generated in the corner 128 and the joint 142 is reduced, so it is preferable that the upper limit of (Ds1-Ds2) / 2 be (Ds1-Ds2) / 2≦20T.

[0030] The electrode-embedded member 100 may be provided with a plurality of electrodes 130. For example, by providing a heater electrode and an electrostatic attraction electrode, the electrode-embedded member 100 can be used as a heater-equipped electrostatic chuck.

[0031] In addition to the above, the electrode-embedding member 100 also includes the necessary terminals 150 and terminal holes 152. This allows power to be supplied to the electrodes .

[0032] FIG. 3 is a schematic cross-sectional view showing a modified example of an electrode-embedded member according to this embodiment. FIG. 4 is a partial cross-sectional view of the electrode-embedded member of FIG. 3. As shown in FIGS. 3 and 4, the cross-sectional curve extending from the lower surface 116 of the substrate body to the side surface 122 of the convex portion preferably has two or more inflection points 124. By making the cross-sectional curve a curve having two or more inflection points 124, the lower surface 116 of the substrate body and the side surface 122 of the convex portion can be shaped in various ways, reducing stresses generated in corners 128 and joints 142 of the support member 140. This also allows for shapes in which the thickness of the convex portion 118 is increased.

[0033] 3 and 4, when the cross-sectional curve is a curve having two or more inflection points 124, it is preferable that the cross section of the side surface 122 of the convex portion near the joint and the side surface of the support member near the joint be a continuous curve. This allows the side surface 122 of the convex portion and the side surface of the support member to be smoothly connected, further alleviating stress generated at the joint 142 of the support member 140. Furthermore, even if the number of inflection points is two or more, the side surface 122 of the convex portion and the lower surface 120 of the convex portion may be smoothly connected.

[0034] The electrode embedding member 100 of the present invention alleviates stresses that occur at the corners and at the joints of the support member, thereby reducing the risk of damage to the corners and joints and the risk of poor airtightness.

[0035] [Method for manufacturing electrode-embedded members] Next, a method for manufacturing the electrode-embedded member according to the present embodiment will be described. The electrode-embedded member according to the present embodiment is manufactured, for example, by a molded body hot pressing method described below. Note that the manufacturing method is not limited to this method, and may be, for example, a powder hot pressing method or a conventional green sheet lamination method. The powder hot pressing method is a method in which ceramic raw material powder and predetermined heating resistors and electrodes are alternately stacked to embed the heating resistors and electrodes inside the ceramic, and then the resultant is uniaxial hot press fired.

[0036] The manufacturing method of an electrode-embedded member according to an embodiment of the present invention using a molded body hot pressing method includes a ceramic molded body forming process, a ceramic degreased body producing process, a ceramic substrate precursor forming process, a ceramic substrate firing process, a curved surface processing process, a support member molded body forming process, a support member degreased body producing process, a support member firing process, and a joining process.

[0037] In the ceramic green body forming process, for example, a plurality of ceramic green bodies are formed from a first ceramic raw material powder containing AlN as the main component and Y as a sintering aid. For example, additives such as Y2O3 as the Y component of the sintering aid, binder, plasticizer, dispersant, etc. are appropriately added to the ceramic raw material powder and mixed to prepare a slurry, and granules (first ceramic raw material powder) are formed by a method such as spray drying, and then the granules are pressure-molded to form a plurality of ceramic green bodies. In addition to aluminum nitride, silicon carbide, aluminum oxide, silicon nitride, etc. can be used as the raw ceramic powder.

[0038] The ceramic raw material powder preferably has a high purity, preferably 96% or more, more preferably 98% or more, and preferably has an average particle size of 0.1 μm to 1.0 μm.

[0039] The mixing method may be either wet or dry, and a mixer such as a ball mill or a vibration mill may be used. The molding method may be a known method such as uniaxial pressing or cold isostatic pressing (CIP). The method for forming the ceramic compact is not limited to pressure molding; for example, green sheet lamination or slip casting may also be used. The ceramic compact can be manufactured by appropriately degreasing or further calcining the resulting product.

[0040] After molding, the ceramic molded body may be machined to adjust its shape. Also, a groove may be formed on one side of the ceramic molded body (the surface to be bonded to another ceramic molded body) to match the shape of the electrode. Machining may be performed after degreasing.

[0041] In the ceramic degreased body manufacturing step, a plurality of ceramic molded bodies are degreased at a predetermined temperature or higher for a predetermined time or longer to manufacture a plurality of ceramic degreased bodies.

[0042] The ceramic compact is heat-treated at a temperature of, for example, 500°C to 900°C to produce a degreased ceramic body. The degreasing time is preferably 1 hour to 120 hours. An atmospheric or nitrogen atmosphere furnace can be used for degreasing, but an atmospheric furnace is preferred because it is important to remove the organic components of the binder.

[0043] In the ceramic substrate precursor forming step, an electrode is prepared, and the electrode and a plurality of ceramic degreased bodies are combined to form a ceramic substrate precursor having a substrate mounting surface on its upper surface, formed in a flat plate shape, and having the electrode embedded therein. The convex portions may be roughly formed at this stage, or may be formed by grinding, polishing, or the like after firing.

[0044] The electrodes are prepared in a shape that corresponds to the design of the electrode-embedding member. The electrodes can be in various shapes, such as mesh or foil, and can be made of various materials, such as molybdenum or tungsten.

[0045] In the ceramic substrate firing process, the formed ceramic substrate precursor is uniaxially pressurized and fired in a direction perpendicular to the substrate mounting surface to fire the ceramic substrate. The firing conditions vary depending on the material, but when using ceramics whose main component is AlN, the pressure applied is preferably 1 MPa or more. The firing temperature is preferably 1700°C or higher and 2000°C or lower. The firing time is preferably 1 hour or higher and 12 hours or lower, and more preferably 1 hour or higher and 5 hours or lower. The firing atmosphere is, for example, a nitrogen or inert gas atmosphere, but may also be a vacuum atmosphere. As a result, multiple degreased ceramic bodies are sintered to form a ceramic sintered body, which is integrated to obtain a ceramic substrate with embedded electrodes.

[0046] In the curved surface processing step, the surface of the ceramic substrate from the lower surface of the substrate body to the side surface of the convex portion is processed so that the cross section of the lower surface of the substrate body of the ceramic substrate and the cross section of the side surface of the convex portion are formed by a continuous curve having an inflection point in a cross section including the central axis of the ceramic substrate. The curved surface processing step may be performed after the joining step with the support member.

[0047] It is preferable that there are two or more inflection points in the cross-sectional curve. Furthermore, it is preferable that the processing be performed so that the diameter Ds1 of the boundary between the protrusions and the substrate main body and the diameter Ds2 of the lower surface of the protrusions satisfy 1.1≦Ds1 / Ds2≦1.5. Furthermore, it is preferable that the processing be performed so that the diameter Ds1 of the boundary between the protrusions and the substrate main body, the diameter Ds2 of the lower surface of the protrusions, and the thickness T of the protrusions satisfy (Ds1-Ds2) / 2≧T.

[0048] In the support member compact forming step, the support member compact is formed from a second ceramic raw material powder, which may contain, for example, AlN as the main component and a Y component as a sintering aid, or no sintering aid is added. The method for producing the second ceramic raw material powder and the method for forming the support member compact may be the same as those in the ceramic compact forming step. It is preferable that the second ceramic raw material powder does not contain a sintering aid.

[0049] In the support member degreased body preparation process, the support member molded body is degreased at a predetermined temperature or higher for a predetermined time or longer to prepare a support member degreased body. The numerical ranges of the degreasing conditions for the support member molded body may be the same as those in the ceramic degreased body preparation process. The support member degreased body preparation process and the ceramic degreased body preparation process may be performed simultaneously.

[0050] In the support member firing process, the degreased support member is fired to form a support member that supports the ceramic substrate. Firing conditions vary depending on the material, but when using ceramics whose main component is AlN, the support member is preferably fired at atmospheric pressure. The firing temperature is preferably 1800°C or higher and 2000°C or lower. The firing time is preferably 1 hour or higher and 12 hours or lower. The firing atmosphere is, for example, a nitrogen or inert gas atmosphere, but may also be a vacuum atmosphere.

[0051] In the bonding step, the ceramic base and the support member are bonded to each other by either a bonding method using a bonding material or a bonding method not using a bonding material.

[0052] First, we will explain the bonding method using a bonding material. First, we prepare a bonding material and apply it to at least one of the bonding portion where the support member is bonded to the underside of the protruding portion of the ceramic substrate or the end face of the support member on the bonding portion side. The bonding portion and the end face of the support member on the bonding portion side preferably have a surface roughness Ra of 1.6 μm or less, and more preferably are polished to 0.4 μm or less. The thickness of the applied bonding material is preferably 5 μm or more and 30 μm or less.

[0053] Next, a support member is placed on the bonding portion, and the substrate is heated while being pressurized in a direction perpendicular to the substrate mounting surface. The bonding conditions vary depending on the material, but when using ceramics whose main component is AlN, the pressure applied is preferably 5 kPa or more. The heating temperature is preferably 1500°C or more and 1800°C or less. The heating time is preferably 0.5 hours or more and 5 hours or less. The heating atmosphere is, for example, a nitrogen or inert gas atmosphere, but may also be a vacuum atmosphere. This allows the ceramic substrate and the support member to be bonded.

[0054] The bonding material may be any material capable of bonding the ceramic substrate and the support member. For example, if the ceramic substrate and the support member are made of ceramics primarily composed of AlN, the bonding material may be a paste of mixed powder containing at least Y2O3 powder in AlN powder, which is the same primary component as the ceramic substrate and the support member. Alternatively, the bonding material may be a paste containing 90 wt% to 95 wt% AlN and 5 wt% or more Y2O3, and optionally containing CaO, MgO, ZrO2, and SiO2 to adjust the temperature at which the material becomes molten during bonding.

[0055] Next, a bonding method that does not use a bonding material will be described. A support member is placed at the bonding portion where the support member is bonded to the underside of the protruding portion of the ceramic substrate. The bonding portion and the end face of the support member on the bonding portion side are preferably polished to a surface roughness Ra of 0.1 μm or less. Next, the substrate is heated while being pressurized in a direction perpendicular to the substrate mounting surface. The bonding conditions vary depending on the material, but when using ceramics whose main component is AlN, the pressure applied is preferably 1 MPa or more. The heating temperature is preferably 1600°C or higher and 2000°C or lower. The heating time is preferably 0.5 hours or higher and 6 hours or lower. The heating atmosphere is, for example, a nitrogen or inert gas atmosphere, but may also be a vacuum atmosphere. This allows the ceramic substrate and the support member to be bonded.

[0056] Necessary terminal holes are provided in the fired ceramic substrate. The terminal holes may be drilled before or after bonding to the support member. Terminals are then connected to the terminal holes using brazing material or the like. Ni or the like can be used for the terminals. Au brazing material or the like can also be used for the brazing material.

[0057] By doing this, the stress that occurs at the corners is alleviated, and the stress that occurs at the joints of the support member is also alleviated, resulting in the manufacture of an electrode-embedded member that can reduce the risk of damage to the corners and joints and the risk of poor airtightness.

[0058] A ceramic calcined body preparation step may be provided between the ceramic degreased body preparation step and the ceramic substrate precursor formation step. When the ceramic calcined body preparation step is provided, the ceramic degreased body is calcined at a predetermined temperature to prepare a ceramic calcined body. This allows for higher dimensional accuracy of the electrode-embedded member. Although the calcination conditions vary depending on the material, when using ceramics containing AlN as the main component, the calcination temperature is preferably 1200°C or higher and 1700°C or lower. The calcination time is preferably 0.5 hours or higher and 12 hours or lower. The calcination atmosphere is preferably a nitrogen or inert gas atmosphere, but may also be a vacuum atmosphere. When the calcined body preparation step is provided, machining may be performed after the calcined body preparation step.

[0059] [Examples and Comparative Examples] (Example 1-1) Ceramic raw material powder was prepared, primarily composed of AlN with 5 wt% Y2O3 added. Using this, ceramic compacts measuring 330 mm in diameter and 20 mm in thickness, and ceramic compacts measuring 330 mm in diameter and 25 mm in thickness, were formed using CIP. A groove (Φ292 mm, depth 0.12 mm) for embedding an electrode was formed on one side of the 330 mm diameter, 25 mm thick ceramic compact.

[0060] Next, the two ceramic compacts were degreased at 550°C for 12 hours to produce two ceramic degreased bodies. Next, a molybdenum mesh (wire diameter 0.1 mm, mesh size #50) made of molybdenum with an outermost diameter of 290 mm, cut to a predetermined shape, was prepared as a heating resistor (electrode). The heating resistor was then placed in the groove of the ceramic degreased body, which had grooves formed in it, and sandwiched between the other ceramic degreased body to produce a ceramic substrate precursor.

[0061] Next, the ceramic substrate precursor was subjected to uniaxial hot-press firing at 1800°C for 5 hours while applying a force of 6 MPa perpendicular to the mounting surface. In this way, the electrode-embedded member body was fired. The ceramic substrate after firing measured approximately 330 mm in diameter and 36 mm in thickness. The fired ceramic substrate was then processed prior to bonding. The substrate body had a diameter of 320 mm and a thickness of 20 mm. A convex portion with a predetermined size and side shape was formed on the underside of the ceramic substrate, and the surface roughness of the lower surface of the convex portion at the joint with the support member was finished to Ra 0.1 μm or less. Terminal holes for electrical connection between the electrode and terminal were also machined to reach the embedded electrode.

[0062] The size of the convex portion was such that the diameter Ds1 of the boundary with the substrate main body was 65 mm, the diameter Ds2 of the lower surface of the convex portion was 60 mm, and the thickness T was 5 mm. The shape of the side surface of the convex portion was such that the lower surface of the substrate main body of the ceramic substrate and the side surface of the convex portion were smoothly connected, and the side surface of the convex portion and the lower surface of the convex portion were smoothly connected, with no singular point in between and one inflection point on the side surface of the convex portion. In other words, in a cross section including the central axis of the ceramic substrate, the cross section of the lower surface of the substrate main body of the ceramic substrate and the side surface of the convex portion were formed by a continuous curve, and the curve had a shape with an inflection point.

[0063] Separately, a ceramic compact was formed using CIP using ceramic raw material powder primarily composed of AlN with no added sintering aids, so that after firing it would have a hollow cylindrical shape with an outer diameter of 60 mm, an inner diameter of 50 mm, and a height of 210 mm. This was degreased at 550°C for 12 hours to produce a ceramic degreased body. This ceramic degreased body was then fired at 1900°C for 5 hours at atmospheric pressure to produce a support member. The surface roughness of the end face on the joint side of the fired support member was finished to Ra 0.1 μm or less.

[0064] A support member was then placed at the joining portion of the ceramic substrate, and the substrate was heated at 1700°C for 1 hour while applying a force of 1 MPa in the direction perpendicular to the mounting surface to join the two. A Ni rod measuring 5 mm in diameter and 270 mm in length was then brazed with Au solder at 1000°C in a vacuum. Finally, the outer shape was machined to the desired shape as a finishing process. In this way, the heater with a shaft of Example 1-1 was produced.

[0065] (Example 1-2) In Example 1-2, the heater with a shaft of Example 1-2 was produced under the same conditions as Example 1-1, except that the size of the convex portion was such that the diameter Ds1 of the boundary between the convex portion and the substrate main body was 70 mm, the diameter Ds2 of the lower surface of the convex portion was 60 mm, and the thickness T was 6 mm.

[0066] (Examples 1-3) In Example 1-3, the heater with a shaft of Example 1-3 was produced under the same conditions as Example 1-1, except that the size of the convex portion was such that the diameter Ds1 of the boundary between the convex portion and the substrate main body was 90 mm, the diameter Ds2 of the lower surface of the convex portion was 60 mm, and the thickness T was 10 mm.

[0067] (Examples 1-4) In Example 1-4, the heater with a shaft of Example 1-4 was produced under the same conditions as Example 1-1, except that the size of the convex portion was such that the diameter Ds1 of the boundary between the convex portion and the substrate main body was 100 mm, the diameter Ds2 of the lower surface of the convex portion was 60 mm, and the thickness T was 10 mm.

[0068] Example 2-1 In Example 2-1, the shape of the side of the convex portion was such that the lower surface of the substrate body of the ceramic substrate and the side of the convex portion were smoothly connected, with no singular point in between and two inflection points on the side of the convex portion. That is, in a cross section including the central axis of the ceramic substrate, the cross section of the lower surface of the substrate body of the ceramic substrate and the side of the convex portion were formed by a continuous curve, and this curve had a shape with two inflection points. Furthermore, after joining the shaft, the side of the convex portion and the side of the shaft were processed so that they were smoothly connected. Otherwise, the heater with a shaft of Example 2-1 was produced under the same conditions as Example 1-1.

[0069] (Example 2-2) In Example 2-2, the heater with a shaft of Example 2-2 was produced under the same conditions as Example 2-1, except that the size of the convex portion was such that the diameter Ds1 of the boundary between the convex portion and the substrate main body was 70 mm, the diameter Ds2 of the lower surface of the convex portion was 60 mm, and the thickness T was 8 mm.

[0070] (Example 2-3) In Example 2-3, the heater with a shaft of Example 2-3 was produced under the same conditions as Example 2-1, except that the size of the convex portion was such that the diameter Ds1 of the boundary between the convex portion and the substrate main body was 90 mm, the diameter Ds2 of the lower surface of the convex portion was 60 mm, and the thickness T was 12 mm.

[0071] (Examples 2-4) In Example 2-4, the heater with a shaft of Example 2-4 was produced under the same conditions as Example 2-1, except that the size of the convex portion was such that the diameter Ds1 of the boundary between the convex portion and the substrate main body was 100 mm, the diameter Ds2 of the lower surface of the convex portion was 60 mm, and the thickness T was 12 mm.

[0072] Example 3-1 In Example 3-1, the size of the convex portion was 65 mm in diameter Ds1 at the boundary with the substrate body, 60 mm in diameter Ds2 at the bottom of the convex portion, and 5 mm in thickness T. The bottom surface of the substrate body of the ceramic substrate and the side surface of the convex portion were smoothly connected, and the side surface of the convex portion and the bottom surface of the convex portion were smoothly connected, with no singular point in between and three inflection points on the side surface of the convex portion. That is, in a cross section including the central axis of the ceramic substrate, the cross section of the bottom surface of the substrate body of the ceramic substrate and the side surface of the convex portion were formed by a continuous curve, and this curve had a shape with three inflection points. Otherwise, the heater with a shaft of Example 3-1 was fabricated under the same conditions as Example 1-1.

[0073] (Example 3-2) In Example 3-2, the heater with a shaft of Example 3-2 was produced under the same conditions as Example 3-1, except that the size of the convex portion was such that the diameter Ds1 of the boundary between the convex portion and the substrate main body was 70 mm, the diameter Ds2 of the lower surface of the convex portion was 60 mm, and the thickness T was 8 mm.

[0074] (Example 3-3) In Example 3-3, the heater with a shaft of Example 3-3 was produced under the same conditions as Example 3-1, except that the size of the convex portion was such that the diameter Ds1 of the boundary between the convex portion and the substrate main body was 90 mm, the diameter Ds2 of the lower surface of the convex portion was 60 mm, and the thickness T was 15 mm.

[0075] (Examples 3-4) In Example 2-4, the heater with a shaft of Example 3-4 was produced under the same conditions as Example 3-1, except that the size of the convex portion was such that the diameter Ds1 of the boundary between the convex portion and the substrate main body was 100 mm, the diameter Ds2 of the lower surface of the convex portion was 60 mm, and the thickness T was 15 mm.

[0076] (Comparative Example 1) A heater with a shaft for Comparative Example 1 was produced under the same conditions as in Example 1-1, except that the size of the protrusions was such that the diameter Ds1 of the boundary between the protrusions and the main substrate body was 60 mm, the diameter Ds2 of the bottom surface of the protrusions was 60 mm, the thickness T was 5 mm, and the shape of the side surface of the protrusions was such that the cross section was a straight line perpendicular to the bottom surface of the main substrate body and had no inflection points. The cross section of the corner between the bottom surface of the main substrate body and the side surface of the protrusion had a singular point corresponding to C0.2 mm.

[0077] (Comparative Example 2) In Comparative Example 1, the heater with a shaft of Comparative Example 1 was produced under the same conditions as in Example 1-1, except that the size of the convex portion was such that the diameter Ds1 of the boundary between the convex portion and the main substrate body was 70 mm, the diameter Ds2 of the underside of the convex portion was 60 mm, and the thickness T was 8 mm, and the shape of the side surface of the convex portion was curved in cross section with two inflection points, and a corner corresponding to C0.3 mm, i.e., a singular point, was provided midway along the curve.

[0078] (Visual inspection for damage) The fabricated electrode-embedded members of the Examples and Comparative Examples were placed in a process chamber, and an external power source was connected to the heating resistor, and repeated temperature cycles of 650°C to 200°C were applied. After each cycle, the corners between the underside of the base body of the electrode-embedded member and the side of the protrusion, as well as the joints of the support member, were visually inspected to check for damage. As a result, no visual damage was observed in either the Examples or Comparative Examples, even after 12 cycles.

[0079] (Airtightness test) In addition, a helium leak detector was connected to the end of the support member for each cycle, and helium gas was sprayed from the outside of the support member to check for helium leaks from the joint. -8 Pa·m 3 / s is judged as no leak and is considered to be a pass, and 10 -8 Pa·m 3 / s or more was deemed to be a leak and failed.

[0080] All of the electrode-embedded members of the examples met the pass standard for He leakage even after 12 cycles.

[0081] On the other hand, Comparative Example 1 showed a 10 -8 Pa·m 3 / s or more, and was judged to be unacceptable. -8 Pa·m 3 / s or more, and was judged to have failed. This is thought to be due to the occurrence of invisible cracks at the corners or joints. In other words, it was found that the cross-sectional curve shape of the comparative example was unable to relieve stress at both the corners and joints.

[0082] From the above, it has been confirmed that the electrode-embedding member of the present invention is an electrode-embedding member that can alleviate stresses that occur at the corners of the boundary between the substrate body and the convex portion, as well as stresses that occur at the joints of the support member, thereby reducing the risk of damage to the corners and joints and the risk of poor airtightness.

[0083] The present invention is not limited to the above-described embodiments, and various modifications and equivalents are included within the spirit and scope of the present invention. Furthermore, the structure, shape, number, position, size, etc. of the components shown in each drawing are for the convenience of explanation and may be changed as appropriate. [Explanation of symbols]

[0084] 100 Electrode embedding member 110 Ceramic substrate 112 Base material body 114 Substrate mounting surface 116 Bottom surface of base material body 118 Convex 120 Lower surface of the convex part 122 Side of convex part 124 Inflection Point 126 Boundary between the substrate body and the protrusion 128 Corner 130 electrodes 140 Support member 142 Joint surface 150 terminals 152 terminal hole

Claims

1. An electrode embedding member, a ceramic substrate having a substrate body formed into a flat plate shape from a ceramic sintered body and having a substrate mounting surface on an upper surface thereof, and a protrusion protruding downward from a lower surface of the substrate body facing the substrate mounting surface and formed integrally with the substrate body; an electrode embedded in the substrate body of the ceramic substrate; a support member joined to a lower surface of the convex portion facing the substrate mounting surface, In a cross section including a central axis of the ceramic base, a cross section of the lower surface of the base body of the ceramic base and a cross section of a side surface of the protrusion are formed by a continuous curve, the curve has an inflection point; When the diameter of the boundary between the protrusion and the substrate body is Ds1 and the diameter of the lower surface of the protrusion is Ds2, in the entire protrusion having the inflection point, 1.1≦Ds1 / Ds2≦1.5 An electrode-embedding member characterized by:

2. An electrode-embedding member, a ceramic substrate having a substrate body formed into a flat plate shape from a ceramic sintered body and having a substrate mounting surface on an upper surface thereof, and a protrusion protruding downward from a lower surface of the substrate body facing the substrate mounting surface and formed integrally with the substrate body; an electrode embedded in the substrate body of the ceramic substrate; a support member joined to a lower surface of the convex portion facing the substrate mounting surface, In a cross section including a central axis of the ceramic base, a cross section of the lower surface of the base body of the ceramic base and a cross section of a side surface of the protrusion are formed by a continuous curve, the curve has an inflection point; When the diameter of the boundary between the protrusion and the substrate body is Ds1, the diameter of the lower surface of the protrusion is Ds2, and the thickness of the protrusion is T, in the entire protrusion having the inflection point, (Ds1-Ds2) / 2≧T An electrode-embedding member characterized by:

3. An electrode-embedded member as described in claim 1 or 2, characterized in that the curve has two or more inflection points.

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