JP2007250644A - Heating member and substrate heating device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heating member for eliminating the risk of breaking a heating member at high temperature heating even when the radial center part of the heating member formed of ceramics is set at heating temperature lower than the radial outer side part, and to provide a substrate heating device. <P>SOLUTION: The heating member includes a planar base body 3 which has a heating surface 7 for heating an object to be treated and is formed of the ceramics. Compression residual stress works on the radial center 11 of the base body 3 at normal temperature. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a substrate heating apparatus and a heating member used as a semiconductor manufacturing apparatus. More specifically, the present invention relates to a heating member that can suitably prevent deformation and breakage when a heating surface is heated to a high temperature state, and a substrate heating apparatus using the same.

  In a conventional semiconductor manufacturing apparatus, when a semiconductor thin film is manufactured from a raw material gas by a thermal CVD process or the like, a heating member (ceramic heater) may be used to heat a wafer as a substrate. As this ceramic heater, for example, a so-called two-zone heater is known.

  In this two-zone heater, an inner resistance heating element is embedded in the central portion of the base of the heating member formed in a disk shape, and an outer resistance heating element is embedded in the outer portion in the radial direction. A voltage is applied to the body. Thereby, the difference is provided in the setting value of heating temperature by the radial direction center part and radial direction outer part in a heating member (for example, refer patent document 1).

  When the heating temperature at the central portion in the radial direction of the base is set lower than that at the outer portion in the radial direction, so-called center cool, when the base is heated to a high temperature, the radial outer portion expands more than the radial central portion. The degree of increases. Then, the radially outer portion expands and spreads in the outer circumferential direction, and the radial central portion is pulled toward the radially outer circumferential direction, so that tensile stress acts on the radial central portion. Since a plurality of attachment holes for attaching connection terminals and the like are formed in the central portion in the radial direction, the strength is lower than that in the radially outer portion. Moreover, since the heating member made of ceramics is fragile to tensile stress, it has the property of being easily deformed or damaged when the tensile stress is applied.

As described above, the heating member is prevented from being deformed or damaged by adopting so-called center hot or the like in which the heating temperature in the central portion in the radial direction of the base is set higher than that in the radially outer portion. In order to make this center hot, a tubular member (shaft) is attached to the heating member, and a thermal choke is disposed in the middle of the tubular member to prevent heat release from the tubular member, or the radial center of the heating member Means for providing an auxiliary heater in the section has been used.
JP-A-2005-243243

  However, in film formation using chemical vapor deposition (CVD), when the concentration of reactive species in the gas gradually decreases from the radial center toward the outer circumferential direction, the wafer temperature distribution is set to the center cool, By suppressing the film formation reaction in the central portion in the radial direction and promoting the film formation reaction in the outer peripheral portion, the thickness of the wafer to be formed can be made uniform as a whole. Therefore, in this case, it has been desired to set the temperature of the heating member to a so-called center cool. However, as described above, there is a possibility that deformation or breakage may occur in the central portion in the radial direction of the heating member. It was difficult to adopt.

  Accordingly, an object of the present invention is to prevent the heating member from being deformed or damaged during high-temperature heating, even if the radial center portion of the base of the heating member made of ceramics is set to a lower heating temperature than the radially outer portion. A heating member and a substrate heating apparatus are provided.

  In order to achieve the above object, a heating member according to the present invention has a heating surface for heating an object to be processed, and includes a plate-like substrate formed of ceramics. It is characterized in that compressive residual stress acts on the part in the normal temperature state toward the center in the radial direction.

  The substrate heating apparatus according to the present invention is a substrate heating apparatus in which a tubular member made of ceramics is attached to the back surface of the radially outer portion of the substrate, and the coefficient of thermal expansion of the tubular member is determined by the diameter of the substrate. It is characterized by being set to be larger than the thermal expansion coefficient in the central portion in the direction.

  According to the substrate heating apparatus of the present invention, since the compressive residual stress is acting toward the radial center of the base of the heating member toward the radial center, the radial center of the heating surface of the heating member is Even when used in a state where the temperature distribution is set lower than that of the outer peripheral portion, there is no possibility that deformation or breakage occurs in the central portion in the radial direction.

  That is, when the central portion in the radial direction of the substrate is heated with a temperature distribution having a temperature lower than that of the outer peripheral portion, the outer peripheral portion undergoes thermal expansion and tends to spread in the outer peripheral direction so as to pull the radial central portion. However, since the compressive residual stress acts on the radial central portion at room temperature, the tensile stress generated when heated and spread in the outer peripheral direction is offset with the compressive residual stress. As a result, even when the substrate is heated, no tensile stress is generated in the central portion in the radial direction, so there is no risk of deformation or breakage in the central portion in the radial direction.

  Further, according to another substrate heating apparatus according to the present invention, the compressive residual stress is applied to the front surface layer and the back surface layer in the normal temperature state toward the radial center of the heating member. This cancels out the surface tensile stress generated in the vicinity of the center due to the center cool during heating. Further, the starting point of fracture of ceramics is the surface where tensile stress is generated. According to the present invention, since no tensile stress is generated on the surface, there is no possibility that the heating member is damaged.

  That is, when the base body is heated to become a center cool, the degree of expansion at the radial center portion becomes small with respect to the outer peripheral portion, so that tensile stress acts relatively on the radial center portion. However, since the compressive residual stress acts on the back surface layer, which is the starting point of the fracture when it breaks, at room temperature, the tensile stress that occurs when the center cools is offset with the compressive residual stress. The As a result, even when the base of the heating member is heated to the center cool state, no tensile stress is generated on the surface of the base, so that there is no risk of deformation or breakage of the heating member.

  Hereinafter, embodiments of the present invention will be described.

[First Embodiment]
The heating member according to the present embodiment is a component of the substrate heating apparatus, has a heating surface for heating the workpiece, and is formed in a plate shape made of ceramics. Then, a compressive residual stress is acting on the central portion in the radial direction of the base body in a normal temperature state toward the center in the radial direction, and the thermal expansion coefficient in the central portion in the radial direction of the heating member is expressed by ) Is set smaller than the thermal expansion coefficient. Further, this base is used in a so-called center cool in which the central portion in the radial direction is heated at a lower temperature than the outer peripheral portion.

  FIG. 1 is a cross-sectional view showing a heating member according to the first embodiment.

  As shown in FIG. 1, the heating member 1 includes a disk-shaped base 3 and a cylindrical power supply member 5 attached to the back side of the base 3, and the base 3 and the power supply member 5 are Both are made of aluminum nitride.

  The substrate 3 is formed in a disc shape, and the surface is set to a substrate heating surface 7 on which a wafer is placed. A resistance heating element 9 is embedded in an intermediate portion in the thickness direction.

  The resistance heating element 9 is a substantially concentric coil in a plan view made of molybdenum (Mo), and the whole is continuously connected to one without crossing by bending a single coil a plurality of times in the middle. ing. The heat generation density is changed between the radial center portion 11 and the radial outer portion 13 by changing the coil diameter or the interval between adjacent coil portions. Thereby, different heating temperature distributions in the radial direction of the heating member 9 can be formed. In addition, the heating temperature distribution can be varied gently by gradually changing the coil diameter, pitch, or spacing between adjacent coil portions from the radial center toward the outer peripheral side.

  The resistance heating element 9 is not limited to the coil described above, and may be formed in a mesh shape (net shape). In the case of this mesh, the heat generation density can be appropriately changed by changing the width depending on the part.

  A power supply member mounting groove 15 having a substantially circular shape in plan view and a substantially rectangular cross section is formed in the center of the back surface of the base 3. A bonding layer 17 is formed on the inner surface of the mounting groove 15, and the power supply member 5 is fixed via the bonding layer 17.

  Further, the base 3 is integrally formed from the radial central portion 11 and the radial outer portion 13, but compressive residual stress acts on the radial central portion 11 toward the radial center in a normal temperature state. The thermal expansion coefficient is different between the radial central portion 11 and the radial outer portion 13. Specifically, the thermal expansion coefficient of the radial center portion 11 is set smaller than the thermal expansion coefficient of the radial outer portion 13.

  Thus, in order to change the thermal expansion coefficient between the radial central portion 11 and the radial outer portion 13, a method of appropriately changing the amount of the sintering aid added when the base 3 is manufactured by sintering is suitably used. Can be adopted.

For example, in aluminum nitride (AlN), the sintering aid is changed by changing the addition amount of at least one of the sintering aids of Y ₂ O ₃ , MgO, CaO, Sm ₂ O _3, etc. The thermal expansion coefficient can be changed. In addition, a sintering aid or a secondary component such as TiO ₂ , ZrO ₂ , or SiO ₂ that can change the thermal expansion coefficient may be added as long as the resistivity of the aluminum nitride is not greatly reduced. If the resistivity is greatly lowered, part of the current starts to leak from the embedded resistance heating element through the aluminum nitride material, which affects the heat uniformity. Further, not only oxides but also carbides and nitrides may be added as secondary components.

When the thermal expansion coefficient of the sintering aid oxide is larger than that of aluminum nitride, the thermal expansion coefficient of the aluminum nitride sintered body can be increased by increasing the content of the sintering aid. Since many carbides and nitrides have a smaller thermal expansion coefficient than aluminum nitride, the thermal expansion coefficient of the aluminum nitride sintered body can be reduced by containing them. In alumina, the thermal expansion coefficient can be reduced by containing SiO ₂ .

  The ceramic of the substrate 3 is preferably at least one of aluminum nitride, alumina, silicon carbide, and boron nitride.

  The heating member 1 according to this embodiment is preferably used in a so-called center cool temperature distribution. The center cool refers to a state in which the radial central portion 11 of the disc-shaped heating member 1 is set to a temperature distribution lower than the radial outer portion 13.

  In the case of the heating member 1 having no residual stress in the radial central portion 11, when the heating member 1 is heated by the center cool, the radial outer portion 13 is thermally expanded and pulls the radial central portion 11 in the outer peripheral direction. . For this reason, tensile stress is generated in the radial central portion 11, and the radial central portion 11 is likely to be deformed or damaged.

  Hereinafter, the manufacturing method of the heating member which concerns on embodiment of this invention is demonstrated concretely.

  First, in the manufacturing process of the substrate 3, a molded body of the substrate 3 made of ceramics, in which the resistance heating element 9 is embedded, is manufactured.

Specifically, two large and small cylindrical molds formed concentrically are placed on the mold, and the raw material powder is placed in the smaller mold and between the smaller and larger molds. . These raw material powders are obtained by adding a rare earth oxide such as Y ₂ O ₃ as a sintering aid to main raw materials such as AlN, SiC, SiNx, and sialon. And the quantity of the sintering aid in the raw material powder | flour thrown in in a small mold is smaller than the amount of auxiliary in the raw material powder accommodated between a small mold and a big mold.

  Next, the mold is removed and a uniaxial press is performed to prepare a preform. And after mounting a resistance heating element on this preforming body, a formwork is installed again and the said raw material powder is thrown into each formwork. Thereafter, uniaxial pressing is performed to produce a molded body for the substrate, and then hot pressing is performed at a high temperature of 1700 ° C. or higher to produce a sintered body, which is then ground to produce the substrate 3.

  As the material of the resistance heating element 9, molybdenum, tungsten, tungsten / molybdenum compound, or the like can be used. The resistance heating element 9 to be used is not limited to a linear one, and various forms such as a mesh, a coil spring, a sheet, and a film can be employed.

  Next, in the firing process of the substrate 3, the molded body for the substrate obtained in the production process of the substrate 3 is fired using, for example, a hot press method or a normal pressure sintering method.

  When aluminum nitride powder is used as the raw material powder, it is fired at a temperature of 1700 ° C. to 2000 ° C. for about 1 hour to 10 hours in nitrogen.

The pressure during hot ^{pressing, 20Kg / cm 2 ~1000Kg / cm} 2 or more, more and preferably ^{100Kg / cm 2 ~400Kg / cm 2} . When the hot press method is used, pressure is applied in a uniaxial direction during sintering, so that the adhesion between the resistance heating element 9 and the surrounding ceramic substrate 3 can be improved. In addition, when a metal bulk electrode is used as the resistance heating element 9, it is not deformed by the pressure applied during hot press firing.

  In the processing step of the base 3, the center of the resistance heating element 9 is determined using X-ray imaging or the like, and then the corner 3 is chamfered or the base 3 is subjected to processing for opening holes for extracting electrode terminals.

  Further, an emboss is formed on the surface of the base 3 using a sandblast method or the like, a groove for placing the substrate 3 is formed, holes or grooves for purge gas flowing to the substrate heating surface 7, lift pins, etc. These holes are formed as necessary.

  Note that this substrate processing step is not performed after complete firing, but may be performed using a temporary fired body obtained by firing at a temperature slightly lower than the final firing temperature or by firing for a short time. Processing can be made easier by performing processing before the completion of firing. When the temporary fired body is processed, it is fired again after the processing.

  Further, the power supply member 5 is inserted into the mounting groove 15, the power supply member 5 inserted into the electrode terminal of the resistance heating element 9 is joined, and the terminals are joined.

  As the power supply member 5, a material obtained by processing a conductive material such as Ni into a rod shape, a wire shape, or the like can be used.

  In addition to brazing, the power supply member 5 and the resistance heating element 9 are joined by cutting a screw groove on the outer periphery of the power supply rod, cutting a screw groove on the ceramic base, and screwing the power supply rod into the electrode terminal. In addition, solid phase bonding using caulking, fitting, welding, eutectic, or the like may be employed.

  In this way, by joining the terminal of the resistance heating element 9 and the power supply member 5, when the preliminary completed body is obtained, the resistance heating element 9 is supplied with power to heat the resistance heating element 9.

  Under the actual operating conditions, the temperature distribution of the substrate heating surface 7 of the ceramic substrate 3 is measured using an infrared radiation thermometer.

  The thermal expansion coefficient in the first region 11 is set to be smaller than the thermal expansion coefficient in the adjacent second annular region 13, and the difference is 0.2 ppm / K or more and 1.0 ppm / K. Is less than

  Below, the effect by this embodiment is demonstrated.

  (1) In the high temperature state at the time of sintering, since the substrate 3 composed of portions having different thermal expansion coefficients (the first region 11 and the second annular region 13) has sufficient plasticity, The internal stress acting along the radial direction becomes almost zero. When the temperature is lowered from this state, the plasticity is gradually lost, and each portion of the substrate 3 contracts according to the thermal expansion coefficient specific to that portion. At that time, the portion having a large thermal expansion coefficient tends to shrink more, but since it is fixed to the portion having a small thermal expansion coefficient, it cannot shrink according to the thermal expansion coefficient. On the other hand, the portion having a small thermal expansion coefficient tends to shrink less, but since the portion is fixed to the portion having a large thermal expansion coefficient, the shrinkage becomes larger than the original shrinkage amount. That is, a portion having a large coefficient of thermal expansion is pulled by a portion having a small coefficient of thermal expansion at the time of shrinkage due to a decrease in temperature, thereby generating a residual tensile stress. On the other hand, since the portion having a small thermal expansion coefficient is pushed by the portion having a large thermal expansion coefficient, residual compressive stress is generated. In the present invention, since a material having a small thermal expansion coefficient is used for the radial central portion 11, residual compressive stress is generated in the radial central portion 11 at room temperature.

  Thus, since the compressive residual stress is acting on the radial center part 11 of the base member 3 of the heating member 1 in the normal temperature state toward the radial center, the radial center part of the substrate heating surface 7 in the base body 3. Even when 11 is used in a state in which the temperature distribution is set lower than that of the outer peripheral portion 13, there is no possibility that the radial central portion 11 is deformed or damaged.

  That is, when the radial central portion 11 of the substrate 3 is heated at a temperature distribution lower than that of the outer peripheral portion 13, the outer peripheral portion 13 undergoes thermal expansion and widens in the outer peripheral direction so as to pull the radial central portion 11. I will try. However, since the compressive residual stress is acting on the radial central portion 11 at room temperature, the tensile stress generated when heated and spread in the outer peripheral direction is offset with the compressive residual stress. As a result, even when the heating member 1 is heated, no tensile stress is generated in the radial central portion 11, so there is no risk of deformation or breakage in the radial central portion 11.

  (2) The difference in thermal expansion coefficient between adjacent portions (the first region 11 and the second annular region 13) is preferably 0.2 ppm / K or more and less than 1.0 ppm / K. When the difference in coefficient of thermal expansion is less than 0.2 ppm / K, the effect (1) described above is not sufficiently generated. Moreover, when it becomes 1.0 ppm / K or more, the residual stress which generate | occur | produces at normal temperature will become large too much, and it will become impossible to obtain the heating member which has sufficient intensity | strength.

[Second Embodiment]
Next, a second embodiment will be described. However, the same contents as those of the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

  In this embodiment, the thermal expansion coefficient is gradually reduced from the radially outer side of the base toward the radial center. In order to change this thermal expansion coefficient, the amount of the sintering aid added to the raw material powder is changed. The thermal expansion coefficient in the first region 23 is set to be smaller than the thermal expansion coefficient in the adjacent second annular region 25, and the difference is 0.2 ppm / K or more and 1.0 ppm / K. Is less than

  FIG. 2 is a cross-sectional view showing a heating member according to the second embodiment. The outer shape of the heating member 21 is formed in a disc shape, and the heating member 21 is divided into a plurality of concentric annular regions along the radial direction. The first region 23 is disposed on the innermost radial direction, the second annular region 25 is disposed on the outer peripheral side of the first region 23, and the third annular ring is disposed on the outermost peripheral side. A region 27 is arranged. The first region 23 and the second annular region 25 are subjected to a compressive residual stress radially inward, and the compressive residual stress in the first region 23 is compressed in the second annular region 25. It is larger than the residual stress.

  The manufacturing method of the heating member according to the present embodiment will be described focusing on differences from the first embodiment.

  First, the disk-shaped substrate 29 is produced.

  Three cylindrical molds having different diameters formed concentrically are arranged on the mold. And the mixed powder of raw material powder and a sintering aid is accommodated in each formwork. And the amount of the sintering aid in the mixed powder is gradually increased from the center in the radial direction toward the outer periphery. For example, the amount of sintering aid in the mixed powder in the mold with the smallest diameter is 0.1 wt%, and the sintering aid in the mixed powder accommodated between the smallest mold and the second smallest mold The amount is 2.0 wt%, and the amount of the sintering aid in the mixed powder accommodated on the outermost side is 5.0 wt%.

  From this step onward, the heating member 21 according to the present embodiment can be produced by proceeding with molding in the same procedure as in the first embodiment.

  Below, the effect by this embodiment is demonstrated.

  (1) Since the thermal expansion coefficient of the base 3 of the heating member 21 is gradually reduced from the radially outer side toward the radial center, the residual stress generated at room temperature is gently increased along the radial direction. (Gradually) can be distributed, and at the same time, the difference in thermal expansion coefficient between the radially central portion and the outermost peripheral portion can be increased, so that the residual compressive stress in the radially central portion can be further increased. it can. When such a heating member 21 expands in the outer peripheral direction by being heated to a high temperature in the center cool state, the tensile stress when the first region 23 serving as the central portion in the radial direction is pulled in the outer peripheral direction is increased in the radial direction. It changes gently along. Therefore, when the base member 29 of the heating member 21 is heated, the residual compressive stress generated in the base member 29 at room temperature is gently offset by the tensile stress and can withstand a larger center cool. Become.

  (2) The base body 29 is formed in a disk shape, and a plurality of concentric ring regions 23, 25, 27 are set on the base body 29, and heat is generated between a predetermined ring region and an annular region adjacent thereto. Since the difference in expansion coefficient is 0.2 ppm / K or more and less than 1.0 ppm / K, the difference in thermal expansion coefficient between the radial center and the outermost peripheral part is 0.4 ppm / K or more and 2.0 ppm / K. Can do. In this case, a larger residual compressive stress can be generated in the central portion in the radial direction.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. However, the same contents as those of the first embodiment and the second embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  In the present embodiment, the base 33 constituting the heating member 31 is composed of a front surface layer 35, a back surface layer 37, and an intermediate layer 39, and compressive residual stress acts on the surfaces of the front surface layer 35 and the back surface layer 37 at room temperature. is doing.

  FIG. 3 is a sectional view showing the heating member according to the present embodiment.

  The base body 33 is formed in a disc shape, and has a surface layer 35 disposed on the front surface side, a back surface layer 37 disposed on the back surface side, and an intermediate layer sandwiched between the surface layer 35 and the back surface layer 37. 39.

  And since the thermal expansion coefficient in the intermediate layer 39 is set smaller than the thermal expansion coefficients of the surface layer 35 and the back surface layer 37, the surface layer 35 has a surface (upper surface) and a back surface (lower surface) of the back surface layer 37. Compressive residual stress is acting at room temperature.

  The heating member manufacturing method according to this embodiment will be described focusing on differences from the first embodiment and the second embodiment.

  First, in the manufacturing process of the base body 33, a molded body of the base body 33 made of ceramics in which the resistance heating element 9 is embedded is manufactured.

  Specifically, a cylindrical mold is placed on the mold, and the raw material powder for the back side is put into the mold. Next, the intermediate side raw material powder having a smaller amount of sintering aid added than the back side raw material powder is charged. Furthermore, the raw material powder for the surface side is put on the raw material powder for the intermediate side. The raw material powder for the back side and the raw material powder for the front side have the same amount of sintering aid to be added, and the amount of the sintering aid in the raw material powder for the intermediate side is More than the raw material powder and the raw material powder for the surface side.

  From this step onward, the heating member according to the present embodiment can be produced by proceeding with molding in the same procedure as in the first and second embodiments.

  Below, the effect by this embodiment is demonstrated.

  (1) Since compressive residual stress is acting on the front surface of the surface layer 35 and the back surface of the back surface layer 37 toward the center in the radial direction of the base material 33 at room temperature, when the base material 33 is heated, No deformation or breakage occurs.

  That is, when the base body 33 is heated so as to be center-cooled, tensile stress tends to be generated in the central portion in the radial direction. However, since the compressive residual stress acts on the surface of the base body 33 at room temperature, it is offset by the compressive residual stress. As a result, when the base body 33 is damaged, no tensile stress is generated on the front and back surfaces, which are the starting points of the failure, so that there is no risk of deformation or damage in the base body 33.

  (2) Since the thermal expansion coefficient of the intermediate layer 39 is set larger than the thermal expansion coefficients of the front surface layer 35 and the back surface layer 37, compressive residual stress is generated on the front surface and the back surface of the base 33 after sintering. . That is, since the substrate 33 is plastic in a high temperature state during sintering, almost no stress is generated inside. When the temperature is lowered from the high temperature state during sintering to room temperature, the plasticity is lost, and the intermediate layer tends to shrink more than the front surface layer and the back surface layer. When the intermediate layer is pulled in the radial center direction, compressive residual stress is generated in the front surface layer and the back surface layer. In this way, the above-described effect (1) is obtained, and when the base body 33 is heated to the center cool, no tensile stress is generated on the front and back surfaces of the base body 33. The fear is reduced.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. However, the same contents as those in the first to third embodiments described above are denoted by the same reference numerals, and the description thereof is omitted.

  The substrate heating apparatus according to the present embodiment is obtained by joining a substantially cylindrical tubular member (shaft) to the heating member according to the first embodiment.

  FIG. 4 is a cross-sectional view of a substrate heating apparatus according to a fourth embodiment of the present invention.

  This substrate heating device 41 is arranged on a base 3 formed in a disk shape, a cylindrical power supply member 5 bonded to the back side of the base 3, and an outer peripheral side of the power supply member 5. The base 3 and the tubular member 43 are both formed of a ceramic sintered body. The tubular member (shaft) 43 is joined to the back side.

  As in the first embodiment, the base 3 is integrally formed from the radial central portion 11 and the radial outer portion 13, but remains compressed at the radial central portion 11 toward the radial center in the normal temperature state. Stress is acting, and the thermal expansion coefficient is different between the radial central portion 11 and the radial outer portion 13. Specifically, the thermal expansion coefficient of the radial center portion 11 is set smaller than the thermal expansion coefficient of the radial outer portion 13.

  Thus, in order to change the thermal expansion coefficient between the radial central portion 11 and the radial outer portion 13, a method of appropriately changing the amount of the sintering aid added when the base 3 is manufactured by sintering is suitably used. Can be adopted.

  The tubular member 43 has an upper portion formed in the large diameter portion 45 and a lower portion formed in the small diameter portion 47 having a smaller diameter than the large diameter portion 45. The upper end of the large diameter portion 45 is bonded to the back surface of the radially outer portion 13 of the base 3. The thermal expansion coefficient of the tubular member 43 is preferably set to be larger than the thermal expansion coefficient at the radial center portion 11 of the base 3.

  More preferably, the thermal expansion coefficient of the tubular member 43 is preferably set to the same or substantially the same value as the thermal expansion coefficient of the radially outer portion 13 of the base 3. Specifically, it is preferable to set the difference between the thermal expansion coefficient of the tubular member 43 and the thermal expansion coefficient of the radially outer portion 13 of the base 3 to 0.1 ppm / K or less.

  Hereinafter, a method for manufacturing the substrate heating apparatus according to the present embodiment will be briefly described.

  First, a heating member is manufactured by the method described in the first embodiment.

  On the other hand, in the production process of the tubular member 43, first, a molded body of the tubular member 43 is produced using raw material powder.

  Next, the obtained molded body is sintered, and the sintered body obtained by the sintering is processed. In the tubular member manufacturing step, it is desirable to use a raw material powder having the same quality as the radially outer portion 13 of the base body 3 as a raw material powder in order to obtain good bonding with the base body.

  Although various methods can be used as the molding method, it is preferable to use a CIP (Cold Isostatic Pressing) method, slip casting, or the like suitable for molding a relatively complicated shape.

  In the tubular member firing step, the sintered body obtained in the above-described tubular member manufacturing step is fired. However, since the shape of the sintered body is complicated, it is desirable to fire using a normal pressure firing method.

  When AlN is used as a ceramic raw material, it is fired in nitrogen at a temperature of 1700 ° C. to 2000 ° C. for about 1 hour to 10 hours.

  In the tubular member processing step, lapping processing of the sintered body surface and the joint surface is performed.

  Next, in the tubular member joining step, the aforementioned base and tubular member are joined.

  In this tubular member joining step, after applying a rare earth compound as a joining agent to one or both of the joining surfaces, the joining surfaces are bonded together, and heat treatment is performed at a temperature of 1700 ° C. to 1900 ° C. in a nitrogen atmosphere.

  If necessary, uniaxial pressure may be applied from a direction perpendicular to the joint surface, and a predetermined pressure may be applied. In this way, solid phase bonding between the substrate and the tubular member is performed.

  In addition to the solid-phase bonding described above, the base member and the tubular member may be joined together by mechanical joining with a sealing material using brazing, O-ring, metal packing, or the like.

  Further, the power feeding member 5 is inserted into the tubular member 43, the electrode terminal of the resistance heating element 9 and the power feeding member 5 inserted into the shaft are joined, and the terminals are joined.

  As the power supply member 5, a material obtained by processing a conductive material such as Ni into a rod shape, a wire shape, or the like can be used.

  In addition to brazing, the power supply member 5 and the resistance heating element 9 are joined by cutting a screw groove on the outer periphery of the power supply rod, cutting a screw groove on the ceramic base, and screwing the power supply rod into the electrode terminal. In addition, solid phase bonding using caulking, fitting, welding, eutectic, or the like may be employed.

  The effect by this embodiment is demonstrated.

  In this embodiment, since the difference between the thermal expansion coefficient of the tubular member 43 and the thermal expansion coefficient of the radially outer portion 13 of the base 3 is set to 0.1 ppm / K or less, the heating in the substrate heating device 41 is performed. When the member 1 is heated, the degree of expansion in the radially outer portion 13 of the base 3 and the degree of expansion of the tubular member 43 substantially coincide. Accordingly, the bonding strength of the tubular member 43 to the base body 3 can be kept high during heating. Furthermore, since the thermal expansion coefficient of the tubular member 43 is larger than the thermal expansion coefficient of the central portion in the radial direction of the base 3, the tubular member 43 is larger than the central portion of the base 3 during cooling after being joined at a high temperature. In an attempt to shrink, the radially central portion of the substrate 3 is compressed together with the radially outer portion of the substrate 3. Accordingly, it is possible to generate a larger compressive residual stress in the central portion in the radial direction of the base body 3 than when the tubular member 43 is not joined. Therefore, by attaching the tubular member 43, there is no possibility that the heating member is damaged even if larger center cool heating is performed.

  Hereinafter, the present invention will be described more specifically with reference to examples.

  In this example, a heating member composed of a base body made of aluminum nitride and a tubular member (shaft) joined to the base body was produced, and the damage state when the heating member was heated to the center cool was examined.

  First, a substrate was produced according to the manufacturing method in the embodiment described above.

[Example 1]
First, two large and small cylindrical molds were placed on a mold, and raw material powder containing a sintering aid was put into the mold. Thereafter, the mold was removed and uniaxial pressing was performed to produce a molded body.

  After placing the heater element on the molded body, a cylindrical formwork was again installed, each raw material powder was poured into a predetermined position, and uniaxial pressing was performed again to produce a molded body for a substrate. The molded body for the substrate was hot pressed at a temperature of 1700 ° C. or higher to produce a sintered body, which was then ground to produce a substrate.

The diameter of the outer periphery of the base was 325 mm, the diameter of the central portion in the radial direction was 62 mm, and the thickness was 15 mm. Further, the raw material powder is obtained by adding Y ₂ O ₃ as a sintering aid to a main raw material made of AlN, the amount of the auxiliary agent in the radial central portion is 0.1 wt%, and the auxiliary agent in the radial outer portion. The amount was 5.0 wt%.

  A countersink hole was provided at the center of the base so that the two ends of the resistance heating element embedded in the base were exposed, and the power supply member was joined to the resistance heating element by brazing. If necessary, a disk-shaped mesh electrode serving as an RF electrode may be embedded in the substrate, and a power feeding member may be joined to the mesh electrode. Furthermore, you may provide the hole for inserting the thermocouple for measuring temperature.

  In addition, the heating member can change the temperature distribution of the heating member as will be described later by appropriately changing the design such as the shape of the heater element to be embedded. Since the purpose here is the temperature distribution of the center cool, various heater elements were created so that the heat density at the center was smaller than the heat density at the outer periphery, and each heater element was embedded in three pieces. A heating member was prepared.

  Next, the produced substrate was placed in a water-cooled vacuum vessel.

  Thereafter, the heating member is accommodated in a vacuum vessel of nitrogen atmosphere with a pressure of 50 Torr, the voltage is applied to the power supply member, the temperature of the thermocouple inserted into the hole of the substrate is monitored, and the applied voltage is controlled. The temperature was raised to 470 ° C. and held.

  In addition, the heater element was changed to prepare three substrates, and it was confirmed how many of these three members were heated and damaged.

[Example 2]
Next, the second embodiment will be described, but the same contents as those of the first embodiment will be omitted or simplified.

  First, three large and small cylindrical molds were placed on a mold, and raw material powder containing a sintering aid was put into the mold. Thereafter, the mold was removed and uniaxial pressing was performed to produce a molded body.

  After placing the heater element on the molded body, a cylindrical formwork was again installed, each raw material powder was poured into a predetermined position, and uniaxial pressing was performed again to produce a molded body for a substrate. The molded body for the substrate was hot pressed at a temperature of 1700 ° C. or higher to produce a sintered body, which was then ground to produce a substrate.

The diameter of the outer periphery of the substrate was 325 mm, the diameter of the central portion in the radial direction was 62 mm, the diameter of the intermediate portion on the outer peripheral side of the central portion in the radial direction was 105 mm, and the thickness was 15 mm. The raw material powder is obtained by adding Y ₂ O ₃ as a sintering aid to a main raw material made of AlN. The amount of auxiliary agent in the radial center is 0.1 wt%, and the amount of auxiliary agent in the intermediate portion is The amount of auxiliary at the outer side in the radial direction was 2.0 wt% and 5.0 wt%.

  A power feeding member was joined to the resistance heating element of the base by brazing.

  Next, the produced substrate was placed in a water-cooled vacuum vessel.

  Thereafter, the heating member is accommodated in a vacuum vessel of nitrogen atmosphere with a pressure of 50 Torr, the voltage is applied to the power supply member, the temperature of the thermocouple inserted into the hole of the substrate is monitored, and the applied voltage is controlled. The temperature was raised to 470 ° C. and held.

  In addition, the heater element was changed to prepare three substrates, and it was confirmed how many of these three members were heated and damaged.

[Example 3]
Next, the third embodiment will be described, but the same contents as those of the first and second embodiments are omitted or simplified.

  First, raw material powder containing a sintering aid was put into the mold. Then, the back surface layer was produced by performing uniaxial press.

  After placing the heater element on this back layer, the raw material powder was poured and uniaxial pressing was performed again to form an intermediate layer on the back layer. After pouring raw material powder onto this intermediate layer, uniaxial pressing was performed again to form a surface layer. The molded laminate was hot pressed at a temperature of 1700 ° C. or higher to produce a sintered body, which was then ground to produce a three-layer substrate.

The outer diameter of the base was 325 mm and the thickness was 15 mm. The raw material powder is obtained by adding Y ₂ O ₃ as a sintering aid to a main raw material made of AlN. The amount of auxiliary agent for the front and back layers is 0.1 wt%, and the auxiliary agent amount for the intermediate layer Was 5.0 wt%.

  A power feeding member was joined to the resistance heating element of the base by brazing.

  The produced substrate was placed in a water-cooled vacuum vessel.

  Thereafter, the heating member is accommodated in a vacuum vessel of nitrogen atmosphere with a pressure of 50 Torr, the voltage is applied to the power supply member, the temperature of the thermocouple inserted into the hole of the substrate is monitored, and the applied voltage is controlled. The temperature was raised to 470 ° C. and held.

  In addition, three each base | substrate was produced and it was confirmed whether how many of these three were heated up and damaged.

[Example 4]
Next, although Example 4 is demonstrated, about the content similar to the said Examples 1-3, it simplifies.

  First, the base of the heating member was produced by the same method as in Example 1 described above.

Next, a substantially cylindrical tubular member (shaft) was prepared by CIP molding and atmospheric sintering using raw material powder containing a sintering aid, and ground into a predetermined shape. The raw material powder is obtained by adding Y ₂ O ₃ as a sintering aid to a main raw material made of AlN, and the amount of the auxiliary agent is set to 5.0 wt%, which is the same as that of the radially outer portion of the substrate. This tubular member was solid-phase bonded at 1700 ° C. to the power supply member mounting portion at the center of the base, and then the power supply member was bonded as described above. As shown in FIG. 4, the tubular member has a length of 150 mm and a flange at the lower end, and the end face of the flange is polished so as to be surely sealed.

[Comparative Example 1]
In the heating member according to Comparative Example 1, the entire base was formed from a uniform aluminum nitride sintered body. The raw material powder was obtained by adding Y ₂ O ₃ as a sintering aid to a main raw material made of AlN, and the amount of the auxiliary agent was 5.0 wt%.

[Comparative Example 2]
In the substrate heating apparatus according to Comparative Example 2, a tubular member having the same thermal expansion coefficient as that of the base was bonded to the back surface of the base of Comparative Example 1. That is, the raw material powder is obtained by adding Y ₂ O ₃ as a sintering aid to a main raw material made of AlN, and the amount of the auxiliary agent is 5.0 wt%.

[Evaluation]
About the heating member and substrate heating apparatus obtained in Example 1 and Comparative Example 2, the substrate surface temperature measurement and the damage rate due to heating were examined. The results are shown in Table 1. In Table 1, “center cool aim” indicates a target value of the difference in temperature between the center in the radial direction of the substrate and the outer periphery, and is expressed by (outer periphery temperature−center temperature). A sets the center cool target at 0 ° C, B sets the center cool target at 50 ° C, and C sets the center cool target at 80 ° C. And the value which actually measured the temperature difference in the radial direction center and outer periphery of a base | substrate is shown as a center cool degree.

  The heating member and substrate heating apparatus obtained in Example 1 and Comparative Example 2 were placed in a water-cooled vacuum vessel. Three alumina pins to be in point contact were arranged at the apex portions of an equilateral triangle with an interval of 200 mm, and the heating member and the substrate of the substrate heating apparatus were placed on these alumina pins.

  Thereafter, the heating member and the substrate heating device are accommodated in a vacuum vessel of nitrogen atmosphere with a pressure of 50 Torr, the voltage is applied to the power supply member, and the temperature of the thermocouple inserted in the hole of the base is monitored, and the applied voltage is set. The substrate was heated to 470 ° C. and held.

  Note that three substrates were prepared for Examples 1 to 4, and two were prepared for Comparative Examples 1 and 2, and it was confirmed how many of these substrates were damaged by heating.

  There was a quartz window at the top of the vacuum vessel, and an IR camera was installed outside the window, and the radiation temperature distribution on the surface of the substrate in the vacuum vessel was measured. From the measurement result of the temperature distribution, the maximum temperature and the minimum temperature in a circle portion having a diameter of 300 mm from the center of the substrate were read. By the resistance heating element design that becomes the center cool, the temperature near the center becomes the minimum temperature, and the vicinity of the outer periphery in the circle portion having a diameter of 300 mm becomes the maximum temperature. The difference between the maximum temperature and the minimum temperature was calculated as the center cool degree.

  The base body sintered at the time of hot pressing has almost no internal stress at a high temperature. However, when the substrate shrinks due to cooling, the portion with a large thermal expansion coefficient tends to shrink more than the portion with a small thermal expansion coefficient. Compressive stress is generated as residual stress. That is, in Examples 1 and 2, a compressive stress is generated in the central portion of the sintered base, and a tensile stress is generated in the radially outer portion. In Example 3, tensile stress is generated in the intermediate layer of the sintered substrate, and compressive stress is generated in the front surface layer and the back surface layer.

  Here, according to the embodiment of the present invention, even when the center cool degree, which is the difference between the maximum temperature near the outer periphery of the substrate and the minimum temperature near the center, is in the vicinity of 80 ° C., the substrate is not damaged. Turned out to be reliable. Furthermore, in the case of the substrate heating apparatus of Example 4, it was not damaged even when the center cool degree was 100 ° C. In Comparative Example 1, two of the three pieces were damaged when the center cool degree was 46 ° C.

  In the first and second embodiments, since compressive residual stress is generated in the central portion in the radial direction where the holes such as the terminals are formed in the normal temperature state, the central portion in the radial direction when the heating member is heated to the high temperature state. The compressive residual stress cancels out the tensile stress generated in the portion, and the compressive stress remains in the vicinity of the hole. Furthermore, in the so-called center-cooled temperature distribution, the radially outer portion is higher in temperature than the radially central portion, so that the compressive residual stress generated in the radially outer portion cancels out the tensile stress generated by heating and heats up. Since the stress of the entire member becomes uniform, the reliability of the heating member is improved. Therefore, the product of the present invention is not damaged even in the center cool temperature distribution, which may be damaged in the conventional product.

  Further, in Example 3 of the present invention, since the compressive stress is applied to the ceramic surface that is the starting point of breakage when breakage occurs, the breakage does not occur for the same reason as in Examples 1 and 2.

  In Example 4, the tubular member is set to have the same high thermal expansion coefficient as the radially outer portion of the base, and this tubular member is joined to the radially outer portion of the base. A larger residual compressive stress is generated, and even a larger center cool does not break.

  In the present invention, since the thermal expansion coefficient of the heating member or tubular member is controlled by the amount of the sintering aid to be added, the sintering aid diffuses in a short range during hot pressing between regions having different thermal expansion coefficients. As a result, the buffer region is integrated to reduce the steep residual stress generated in the vicinity of the boundary between the regions, so that peeling at the boundary is difficult to occur and the structure is highly reliable.

  If the number of regions having different thermal expansion is three or more as in the second embodiment, the difference in thermal expansion coefficient between the radially central portion and the outermost peripheral portion increases, so that the compressive residual stress generated in the radially central portion. Since the difference in thermal expansion coefficient between adjacent regions can be reduced, the residual stress distribution due to the difference in thermal expansion occurring at these boundaries does not become steep, and the reliability is further improved. That is, with such a configuration, a larger center cool temperature distribution can be realized. Furthermore, the thermal expansion coefficient may be gradually changed gradually from the center toward the outer periphery.

In the same manner as in Example 1, 0.1 wt% of _Y 2 _{O 3} in the radial center part, when using the added aluminum nitride 30 wt% of _Y 2 _{O 3} on the outer peripheral side, after firing of the heating member, The heating member was damaged. The coefficient of thermal expansion of 30 wt% aluminum nitride cut out from the broken piece was measured and found to be 6.3 ppm / K. When Y ₂ O ₃ was used as the sintering aid for AlN, the thermal expansion coefficient was 5.7 ppm / K at 5 wt% Y ₂ O ₃ , and 5.3 ppm / K at 0.1 wt%.

On the other hand, in the same manner as in Example 4, when 0.1 wt% Y ₂ O ₃ was used in the radial central portion and 1 wt% Y ₂ O ₃ aluminum nitride was used in the radial outer portion and the tubular member, the center cool The damage was 1/3 at 76 ° C. The coefficient of thermal expansion of aluminum nitride in the 1 wt% Y ₂ O ₃ portion was 5.4 ppm / K. From this, it can be seen that the effect of the present invention is small when the difference in thermal expansion coefficient between adjacent regions is as small as 0.1 ppm / K.

  From these, it can be seen that the difference in thermal expansion coefficient between adjacent regions in the substrate is more preferably 0.2 ppm / K or more and less than 1.0 ppm / K.

[Other examples]
A heating member was produced in the same manner as in Example 1 using alumina as the base material instead of aluminum nitride and using SiO ₂ as the sintering aid. That is, 7 wt% of SiO ₂ was added to the central portion in the radial direction, and 1 wt% of SiO ₂ was added to the radially outer portion. In this case, since SiO ₂ has a smaller thermal expansion coefficient than alumina, the thermal expansion coefficient in the central portion can be reduced and the thermal expansion coefficient in the outer peripheral portion can be increased. Separately, when the thermal expansion coefficient was measured with the prepared test piece, alumina containing 7 wt% of SiO ₂ was 6.6 ppm / K, and alumina containing 1 wt% of SiO ₂ was 7.2 ppm / K.

  When the heating member thus prepared was evaluated at 300 ° C. in the same manner as described above, it was not damaged even at a center cool of 45 ° C.

On the other hand, as a comparative example, a heating member in which the entire substrate was made of only alumina containing 1 wt% of SiO ₂ was broken at a center cool degree of 12 ° C. Thus, it has been found that a heating member capable of center cool heating can also be obtained for alumina according to the present invention.

It is sectional drawing of the heating member by 1st Embodiment of this invention. It is sectional drawing of the heating member by 2nd Embodiment of this invention. It is sectional drawing of the heating member by 3rd Embodiment of this invention. It is sectional drawing of the substrate heating apparatus by 4th Embodiment of this invention.

Explanation of symbols

1,21,31 Heating member 3,29,33 Base 7 Heating surface (substrate heating surface)
11 radially central portion 13 radially outer portion 35 surface layer 37 back surface layer 39 intermediate layer

Claims (12)

In a heating member having a heating surface for heating an object to be processed and including a plate-like substrate formed of ceramics,
A heating member, wherein a compressive residual stress is applied to a central portion in a radial direction of the base body in a normal temperature state toward a radial center.   2. The heating member according to claim 1, wherein the heating member of the base body is used in a state in which a radially central portion of the heating surface is set to a temperature distribution lower in temperature than a radially outer portion.   The heating member according to claim 1 or 2, wherein a thermal expansion coefficient in a radially central portion of the base is set to be smaller than a thermal expansion coefficient in a radially outer portion.   The heating member according to claim 3, wherein the thermal expansion coefficient of the base body is gradually reduced from the radially outer side toward the radial center.   The substrate is integrally formed from a plurality of concentric annular parts having a predetermined width, and a difference in thermal expansion coefficient between the predetermined annular part and the adjacent annular part is 0.2 ppm / K or more and The heating member according to claim 3 or 4, wherein the heating member is less than 1.0 ppm / K. In a heating member having a heating surface for heating an object to be processed and including a plate-like substrate formed of ceramics,
The substrate is integrally formed from a surface layer disposed on the front surface side, a back surface layer disposed on the back surface side, and an intermediate layer sandwiched between the surface layer and the back surface layer, and the substrate is formed on the surface layer and the back surface layer. A heating member, wherein a compressive residual stress is acting at normal temperature toward the center in the radial direction.   The heating member according to claim 6, wherein a thermal expansion coefficient in the intermediate layer is set to be larger than thermal expansion coefficients in the front surface layer and the back surface layer.   The heating member according to any one of claims 1 to 7, wherein the ceramic of the base is at least one of aluminum nitride, alumina, silicon carbide, and boron nitride.   The thermal expansion coefficient is provided by forming the base body from a ceramic sintered body and changing the content of the sintering aid along the radial direction or the thickness direction of the base body. 9. The heating member according to 8. Wherein the sintering Yuisukezai _{is, Y 2 O 3, MgO,} CaO, Sm 2 O 3, TiO 2, ZrO 2, heating member according to claim 9, characterized in that at least one of SiO ₂ . A substrate heating apparatus in which a tubular member made of ceramics is attached to the back surface of the radially outer portion of the base body according to any one of claims 1 to 5 and 8 to 10,
A substrate heating apparatus, wherein a thermal expansion coefficient of the tubular member is set to be larger than a thermal expansion coefficient in a central portion in a radial direction of the base body. The substrate heating apparatus according to claim 11, wherein the ceramic of the tubular member is at least one of aluminum nitride, alumina, silicon carbide, and boron nitride.

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