Ceramic heater and method of making same

Abstract

The electrostatic chuck heater has an electric resistance heating element 16 inside the ceramic substrate 12. A groove 17 is provided on the surface of the electric resistance heating element 16 along the length direction of the electric resistance heating element 16. The side wall surface 17a of the groove 17 is inclined with respect to the surface of the ceramic substrate 12. There is no gap between the side wall surface 17a of the groove 17 and the ceramic substrate 12.

Description

TECHNICAL FIELD

[0001] The present application relates to a ceramic heater and a method for manufacturing the same. BACKGROUND

[0002] Conventionally, a ceramic heater for a semiconductor manufacturing apparatus is known. For example, Patent Literature 1 discloses a ceramic heater in which a resistance heating element is provided on a surface of a ceramic substrate and a method for manufacturing the same. Patent Literature 1 also discloses that after forming the resistance heating element in a prescribed pattern on the surface of the ceramic substrate, a groove is formed by irradiating laser light to the resistance heating element, thereby adjusting the resistance value of the resistance heating element. On the other hand, Patent Literature 2 discloses an electrode-embedded sintered body used as a ceramic heater. Patent Literature 2 discloses that as a method for manufacturing the electrode-embedded sintered body, an alumina sintered body or an alumina pre-sintered body is formed, an electrode paste is printed on the alumina sintered body or the alumina pre-sintered body, alumina powder is filled on the electrode paste, and molding is performed, and the molded body is subjected to hot-press sintering.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Laid-Open No. 2002-190373

[0006] Patent Literature 2: Japanese Patent Application Laid-Open No. 2005-343733 SUMMARY

[0007] However, in order to adjust the resistance value of the electrode paste printed on the alumina sintered body or the alumina pre-sintered body in Patent Literature 2, it is considered to irradiate laser light to the electrode paste as in Patent Literature 1, and form a groove. However, when the alumina powder is filled on the electrode paste on which the groove is formed, and molding is performed, and the molded body is subjected to hot-press sintering, a gap is sometimes generated near the side wall of the groove in the alumina ceramic substrate. The gap constitutes a cause of deterioration of heat conduction and reduction of heat uniformity, and is thus not desirable.

[0008] The present application has been made to solve the above-described problems, and has as its main object to provide a ceramic heater in which a resistance heating element having a groove is implanted in a ceramic substrate, and in which heat conduction and heat uniformity are made good.

[0009] The method for manufacturing the ceramic heater of the present application includes the following steps:

[0010] (a) forming a resistance heating element or a precursor thereof in a prescribed pattern on a surface of a first ceramic sintered layer or an unsintered layer;

[0011] (b) irradiating laser light to the resistance heating element or the precursor thereof, and forming a groove in a length direction of the resistance heating element or the precursor thereof;

[0012] (c) a second ceramic un-fired layer is arranged on the surface of the first ceramic fired or un-fired layer in a manner of covering the electric resistance heat generating body or its precursor, to obtain a laminate;

[0013] (d) the laminate is subjected to hot-pressing firing, thereby obtaining a ceramic heater in which the electric resistance heat generating body is implanted in the inside of the ceramic substrate,

[0014] In the process (b), the groove is formed in a manner that the side wall surface of the groove is inclined with respect to the surface of the first ceramic fired or un-fired layer.

[0015] In the process (b) of the method for manufacturing the ceramic heater, the cross-sectional area of the electric resistance heat generating body or its precursor (even the resistance of the electric resistance heat generating body) is adjusted by forming the groove in the electric resistance heat generating body or its precursor. At this time, the groove is formed in a manner that the side wall surface of the groove is inclined with respect to the surface of the first ceramic fired or un-fired layer. In the process (d), when the layered molding body is subjected to hot-pressing firing, since the side wall surface of the groove is inclined, pressure is applied between the side wall surface of the groove and the ceramic powder contained in the second ceramic un-fired layer in a state that they are in close contact, and the layered molding body is fired. Accordingly, it is possible to prevent a gap from being generated between the side wall surface of the groove and the ceramic substrate, and to improve the adhesion strength of the side wall surface of the groove and the ceramic substrate. Therefore, the thermal conductivity and the heat uniformity of the obtained ceramic heater become good.

[0016] Note that the "ceramic fired layer" is a layer of a ceramic that has been fired, and can be a layer of a ceramic fired body (sintered body) or a layer of a ceramic pre-fired body. The "ceramic un-fired layer" is a layer of a ceramic that has not been fired, and can be a layer of a ceramic powder or a layer of a ceramic molding body (including a ceramic molding body obtained by drying a molding body, a ceramic molding body obtained by drying and defatting a molding body, a green sheet, etc.). The "precursor of the electric resistance heat generating body" refers to a product that becomes an electric resistance heat generating body by firing, and for example refers to a product on which a paste of an electric resistance heat generating body is printed. The "laminate" can be a laminate obtained by arranging a second ceramic un-fired layer on the surface of a first ceramic fired or un-fired layer in a manner of covering an electric resistance heat generating body or its precursor, or can be a laminate obtained by further layering other layers (for example, a third ceramic fired or un-fired layer on which an electrode or its precursor is provided on the side of the second ceramic un-fired layer) on the second ceramic un-fired layer.

[0017] The method for manufacturing the ceramic heater of the present application can be such that, in the process (b), the groove is formed in a manner that the inclination angle β of the side wall surface of the groove with respect to the surface of the first ceramic fired or un-fired layer is 45° or less. Accordingly, it is possible to reliably prevent a gap from being generated between the side wall surface of the groove and the ceramic substrate. If the workability is taken into consideration, the inclination angle β of the side wall surface of the groove is preferably 18° or more.

[0018] The method of manufacturing the ceramic heater of the present application can be such that, in the step (b), the grooves are formed in such a manner that the cross-sectional area at each of a plurality of measurement points determined along the length direction of the electric resistance heat generating body or the precursor thereof is the target cross-sectional area. According to this, the shape of the grooves can be determined without measuring the electric resistance of the electric resistance heat generating body or the precursor thereof.

[0019] The method of manufacturing the ceramic heater of the present application can be such that, in the step (b), the depth of the grooves is less than half the thickness of the electric resistance heat generating body or the precursor thereof. According to this, compared to the case where the depth of the grooves is too deep, it is easier to prevent a gap from being generated between the side wall surface of the grooves and the ceramic substrate.

[0020] The method of manufacturing the ceramic heater of the present application can be such that, in the step (a), the electric resistance heat generating body or the precursor thereof is formed in such a manner that the end surface along the length direction of the electric resistance heat generating body or the precursor thereof is inclined with respect to the surface of the first ceramic sintered or unsintered layer. According to this, a gap can be prevented from being generated between the end surface along the length direction of the electric resistance heat generating body and the ceramic substrate, and the adhesion strength of the end surface to the ceramic substrate is improved, so that the heat conductivity and the heat uniformity of the obtained ceramic heater become better. In this case, in the step (a), it is preferable that the electric resistance heat generating body or the precursor thereof is formed in such a manner that the inclination angle of the end surface along the length direction of the electric resistance heat generating body or the precursor thereof with respect to the surface of the first ceramic sintered or unsintered layer is 45° or less. According to this, a gap can be reliably prevented from being generated between the end surface along the length direction of the electric resistance heat generating body and the ceramic substrate.

[0021] The method of manufacturing the ceramic heater of the present application can be such that, in the step (b), the inclination angle of the side wall surface of the grooves is made larger than the inclination angle of the end surface along the length direction of the electric resistance heat generating body or the precursor thereof. The height of the electric resistance heat generating body or the precursor thereof is made larger than the depth of the grooves. Therefore, the inclination of the end surface along the length direction of the electric resistance heat generating body or the precursor thereof is made more gentle, so that a gap can be further prevented from being generated between the end surface of the electric resistance heat generating body of the ceramic heater and the ceramic substrate.

[0022] The ceramic heater of the present application is a ceramic heater in which an electric resistance heat generating body is embedded in a ceramic substrate, and has:

[0023] grooves provided on the surface of the electric resistance heat generating body along the length direction of the electric resistance heat generating body; and

[0024] a side wall surface of the grooves, which is inclined with respect to the surface of the ceramic substrate,

[0025] a gap is not present between the side wall surface of the grooves and the ceramic substrate.

[0026] In the ceramic heater, the side wall surface of the groove is inclined with respect to the surface of the ceramic substrate, and there is no gap between the side wall surface of the groove and the ceramic substrate. Therefore, the heat conductivity and the heat uniformity of the ceramic heater become good. The ceramic heater can be obtained by, for example, the manufacturing method of the ceramic heater described above. The inclination angle α of the side wall surface of the groove with respect to the surface of the ceramic substrate is preferably 27° or less. If the processability is considered, the inclination angle α is preferably 10° or more.

[0027] The ceramic heater of the present application can be such that the opening edge of the groove is a chamfered shape. According to this, as compared with the case where the opening edge of the groove has an angle, a crack starting from the opening edge of the groove is less likely to occur.

[0028] In the ceramic heater of the present application, the depth of the groove is preferably half or less of the thickness of the resistance heat generating body.

[0029] The ceramic heater of the present application can be such that the end surface of the resistance heat generating body in the length direction is inclined with respect to the surface of the ceramic substrate, and there is no gap between the end surface and the ceramic substrate. According to this, the heat conductivity and the heat uniformity of the ceramic heater become better. The inclination angle γ of the end surface of the resistance heat generating body in the length direction with respect to the surface of the ceramic substrate is preferably 27° or less.

[0030] In the ceramic heater of the present application, the inclination angle of the end surface of the resistance heat generating body in the length direction is preferably smaller than the inclination angle of the side wall surface of the groove. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a perspective view of an electrostatic chuck heater 10.

[0032] Figure 2 is an A-A sectional view of Figure 1

[0033] Figure 3 is an explanatory view when looking down on the resistance heat generating body 16.

[0034] Figure 4 is a B-B sectional view of Figure 3

[0035] Figure 5 is a manufacturing process view of the electrostatic chuck heater 10.

[0036] Figure 6 is a sectional view when cutting the resistance heat generating body precursor 66 in a surface including the width direction of the resistance heat generating body precursor 66.

[0037] Figure 7 ​​is a cross-sectional view of the line groove 68.

[0038] Figure 8 is a cross-sectional view of the line groove 68.

[0039] Figure 9 is a cross-sectional view of the line groove 68.

[0040] Figure 10 is a graph showing the results of measuring the shape of the line groove 68 of Example 1.

[0041] Figure 11 is a graph showing the results of measuring the shape of the line groove 68 of Example 1.

[0042] Figure 12 is a histogram in which the horizontal axis represents the height of the resistance heating element precursor 66 and the vertical axis represents degrees. DETAILED DESCRIPTION

[0043] Next, an embodiment of the present application will be described based on the drawings. Figure 1 is a perspective view of the electrostatic chuck heater 10 of the present embodiment, Figure 2 is an A-A cross-sectional view of Figure 1 Figure 3 is a view for explaining when the resistance heating element 16 is viewed from above, Figure 4 is a B-B cross-sectional view of Figure 3

[0044] The electrostatic chuck heater 10 is configured so that the electrostatic electrode 14 and the resistance heating element 16 are implanted in the inside of the ceramic substrate 12. The cooling plate 22 is adhered to the back surface of the electrostatic chuck heater 10 by means of the adhesive layer 26.

[0045] The ceramic substrate 12 is a circular plate made of ceramic (for example, alumina or aluminum nitride). A wafer mounting surface 12a capable of mounting a wafer W is provided on the surface of the ceramic substrate 12.

[0046] The electrostatic electrode 14 is a circular conductive thin film substantially parallel to the wafer mounting surface 12a. A rod-shaped terminal not shown is electrically connected to the electrostatic electrode 14. The rod-shaped terminal extends downward from the cooling plate 22 after passing through the ceramic substrate 12 from the lower surface of the electrostatic electrode 14. The rod-shaped terminal is electrically insulated from the cooling plate 22. The portion of the ceramic substrate 12 above the electrostatic electrode 14 functions as a dielectric layer. As the material of the electrostatic electrode 14, for example, tungsten carbide, tungsten, molybdenum carbide, molybdenum, or the like can be given, and a material having a thermal expansion coefficient close to that of the ceramic to be used is preferred.

[0047] ​​The resistive heating element 16 is a strip of conductive lines disposed on a surface substantially parallel to the wafer mounting surface 12a. The strip of conductive lines is not particularly limited; for example, it can be configured with a width of 0.1–10 mm, a thickness of 0.001–0.1 mm, and a spacing of 0.1–5 mm. The resistive heating element 16 is wired along the entire ceramic substrate 12 in a single-stroke manner from one terminal portion 18 to another terminal portion 20, with the conductive lines not intersecting. Power supply terminals (not shown) are electrically connected to the terminal portions 18 and 20 of the resistive heating element 16. These power supply terminals extend downwards from the lower surface of the resistive heating element 16, passing through the ceramic substrate 12, and then through the cooling plate 22. Furthermore, these power supply terminals are electrically insulated from the cooling plate 22. Examples of materials for the resistive heating element 16 include tungsten carbide, metallic tungsten, molybdenum carbide, and metallic molybdenum; preferably, a material with a coefficient of thermal expansion similar to that of the ceramic to be used.

[0048] like Figure 4 As shown, a groove 17 is provided on the surface of the resistive heating element 16 along its length (direction of current flow). The depth of the groove 17 is naturally less than the thickness of the resistive heating element 16, but preferably less than half the thickness of the resistive heating element 16. The sidewall surface 17a of the groove 17 is inclined relative to the wafer mounting surface 12a of the ceramic substrate 12. There is no gap between the sidewall surface 17a of the groove 17 and the ceramic substrate 12. It should be noted that "no gap" means that no gap is observed when the SEM cross-section of the ceramic substrate 12 is viewed with the naked eye at 150x magnification (the same applies below). The inclination angle α of the sidewall surface 17a relative to the wafer mounting surface 12a is preferably 27° or less. In addition, considering processability, this inclination angle α is preferably 10° or more. The width of the groove 17 is preferably greater than or equal to the depth of the groove 17. The opening edge 17b of the groove 17 is chamfered and does not have an angle. The chamfer can be a C-shaped chamfer or an R-shaped chamfer. The end face 16a of the resistive heating element 16 along its length is inclined relative to the wafer mounting surface 12a of the ceramic substrate 12. There is no gap between the end face 16a and the ceramic substrate 12. The inclination angle γ of the end face 16a relative to the wafer mounting surface 12a is preferably 27° or less. The inclination angle γ of the end face 16a of the resistive heating element 16 is preferably less than the inclination angle α of the sidewall surface 17a of the groove 17.

[0049] The cooling plate 22 is made of metal (e.g., aluminum) and has a built-in refrigerant passage 24 through which refrigerant (e.g., water) can pass. This refrigerant passage 24 is configured such that the refrigerant passes through the entire surface of the ceramic substrate 12. It should be noted that the refrigerant passage 24 has a refrigerant supply port and a refrigerant discharge port (neither shown).

[0050] Next, a use example of the electrostatic chuck heater 10 will be described. In the electrostatic chuck heater 10, a wafer W is placed on the wafer placement surface 12a, and a voltage is applied between the electrostatic electrode 14 and the wafer W, whereby the wafer W is attracted to the wafer placement surface 12a by electrostatic force. In this state, plasma CVD film formation or plasma etching is performed on the wafer W. In addition, the wafer W is heated by applying a voltage to the resistance heater 16, or the wafer W is cooled by circulating a coolant in the coolant passage 24 of the cooling plate 22, whereby the temperature of the wafer W is controlled to be constant. When a voltage is applied to the resistance heater 16, a voltage is applied between the one terminal portion 18 and the other terminal portion 20 of the resistance heater 16. Then, current flows through the resistance heater 16, so that the resistance heater 16 generates heat, and the wafer W is heated.

[0051] In the present embodiment, the grooves 17 are formed on the surface of the resistance heater 16. The resistance heater 16 is divided into a plurality of sections by the one terminal portion 18 and the other terminal portion 20, and the width of the grooves 17 (the depth is substantially constant) is determined for each section. In the section in which the width of the grooves 17 is wide, the cross-sectional area of the resistance heater 16 is small, so the resistance is high, and the amount of heat generated is large. In the section in which the width of the grooves 17 is narrow, the cross-sectional area of the resistance heater 16 is large, so the resistance is low, and the amount of heat generated is small. Therefore, by adjusting the width of the grooves 17 in each section, the amount of heat generated in each section of the resistance heater 16 is made to coincide with the target amount of heat generated.

[0052] Next, a manufacturing example of the electrostatic chuck heater 10 will be described. Figure 5 is a manufacturing process diagram of the electrostatic chuck heater 10, Figure 6 is a cross-sectional view of the resistance heater precursor 66 when the resistance heater precursor 66 is vertically cut in a plane including the width direction of the resistance heater precursor 66, Figure 7 is an explanatory diagram of a process in which the grooves 67 are formed in the resistance heater precursor 66, Figure 8 and Figure 9 is a cross-sectional view of the grooves 68 and the grooves 67 when the resistance heater precursor 66 is vertically cut in a plane including the width direction of the resistance heater precursor 66. Hereinafter, a case in which an alumina substrate is manufactured as the ceramic substrate 12 will be described as an example.

[0053] [1] Production of a molded body (see Figure 5 (A))

[0054] The lower and upper disc-shaped shaped bodies 51, 53 are produced. Each of the shaped bodies 51, 53 is produced, for example, by first placing slurry containing alumina powder (for example, average particle diameter 0.1 to 10 μm), a solvent, a dispersant, and a gelling agent into a molding die, allowing the gelling agent to chemically react within the molding die to gel the slurry, and then releasing the shaped body from the molding die, thereby producing each of the shaped bodies 51, 53. The shaped bodies 51, 53 thus obtained are referred to as mold-cast shaped bodies.

[0055] As the solvent, any solvent that dissolves and disperses the dispersant and the gelling agent can be used without particular limitation. Examples include hydrocarbon-based solvents (toluene, xylene, solvent naphtha, etc.), ether-based solvents (ethylene glycol monoethyl ether, butyl carbitol, butyl carbitol acetate, etc.), alcohol-based solvents (isopropyl alcohol, 1-butanol, ethanol, 2-ethylhexanol, terpineol, ethylene glycol, glycerol, etc.), ketone-based solvents (acetone, methyl ethyl ketone, etc.), ester-based solvents (butyl acetate, dimethyl glutarate, glyceryl triacetate, etc.), and polybasic acid-based solvents (glutaric acid, etc.). Particularly preferably, a solvent having two or more ester bonds, such as a polybasic acid ester (for example, dimethyl glutarate, etc.), an acid ester of a polyhydric alcohol (for example, glyceryl triacetate, etc.), or the like is used.

[0056] As the dispersant, any dispersant that uniformly disperses the alumina powder in the solvent can be used without particular limitation. Examples include polycarboxylic acid-based copolymers, polycarboxylic acid salts, sorbitan fatty acid esters, polyglycerol fatty acid esters, phosphate ester salt-based copolymers, sulfonic acid salt-based copolymers, polyurethane polyester-based copolymers having tertiary amines, and the like. Particularly preferably, a polycarboxylic acid-based copolymer, a polycarboxylic acid salt, or the like is used. By adding this dispersant, the slurry before molding can be made into a low-viscosity slurry having high fluidity.

[0057] As the gelling agent, for example, an isocyanate, a polyhydric alcohol, and a catalyst can be included. Among these, as the isocyanate, any substance having an isocyanate group as a functional group can be used without particular limitation. Examples include toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), or a modified body thereof, and the like. Note that, within the molecule, a reactive functional group other than the isocyanate group can be included, and a large number of reactive functional groups can be included as in a polyisocyanate. As the polyhydric alcohol, any substance having two or more hydroxyl groups capable of reacting with the isocyanate group can be used without particular limitation. Examples include ethylene glycol (EG), polyethylene glycol (PEG), propylene glycol (PG), polypropylene glycol (PPG), polytetramethylene glycol (PTMG), polyhexamethylene glycol (PHMG), polyvinyl alcohol (PVA), and the like. As the catalyst, any substance that promotes the urethane reaction of the isocyanate and the polyhydric alcohol can be used without particular limitation. Examples include triethylenediamine, hexamethylenediamine, 6-dimethylamino-1-hexanol, and the like.

[0058] In this process, it is preferable that first, a solvent and a dispersant are added to the alumina powder in a prescribed ratio, and they are mixed for a prescribed time to prepare a slurry precursor, and then, a gelling agent is added to the slurry precursor, and mixing and vacuum defoaming are performed to produce a slurry. The mixing method in the preparation of the slurry precursor and the slurry is not particularly limited, and, for example, a ball mill, a self-rotation type stirrer, a vibration type stirrer, a propeller type stirrer, or the like can be used. Note that the slurry obtained by adding the gelling agent to the slurry precursor starts the chemical reaction (urethane reaction) of the gelling agent over time, and thus, it is preferable to quickly cast into a molding die. The slurry cast into the molding die is gelled by the chemical reaction of the gelling agent contained in the slurry. The chemical reaction of the gelling agent refers to a reaction in which an isocyanate and a polyol undergo a urethane reaction to become a urethane resin (polyurethane). By the reaction of the gelling agent, the slurry is gelled, and the urethane resin functions as an organic binder.

[0059] [2] Preparation of the calcined body (see Figure 5 (B))

[0060] After drying the lower and upper molded bodies 51, 53, debinding is performed, and further, calcination is performed, whereby the lower and upper calcined bodies 61, 63 are obtained. The purpose of the drying of the molded bodies 51, 53 is to evaporate the solvent contained in the molded bodies 51, 53. The drying temperature and the drying time can be appropriately set according to the solvent used. However, the setting of the drying temperature needs to be made so that the molded bodies 51, 53 do not crack during drying. In addition, the atmosphere can be any one of an atmospheric atmosphere, an inert atmosphere, and a vacuum atmosphere. The purpose of the debinding of the dried molded bodies 51, 53 is to decompose and remove organic matters such as a dispersant, a catalyst, and a binder. The debinding temperature can be appropriately set according to the kind of the organic matter contained, and, for example, can be set to 400 to 600°C. In addition, the atmosphere can be any one of an atmospheric atmosphere, an inert atmosphere, and a vacuum atmosphere. The purpose of the calcination of the debound molded bodies 51, 53 is to increase the strength and to make the handling easy. The calcination temperature is not particularly limited, and, for example, can be set to 750 to 900°C. In addition, the atmosphere can be any one of an atmospheric atmosphere, an inert atmosphere, and a vacuum atmosphere.

[0061] [3] Formation of the electric resistance heat generating body precursor (see Figure 5 (C) and Figure 6 )

[0062] On one side of the lower pre-fired body 61, a paste for the resistance heating element is printed in the same pattern as that for the resistance heating element 16, and then dried to form a resistance heating element precursor 66. On one side of the upper pre-fired body 63, a paste for the electrostatic electrode is printed in the same shape as that for the electrostatic electrode 14, and then dried to form an electrostatic electrode precursor 64. Both pastes contain alumina powder, conductive powder, binder, and solvent. The alumina powder can be, for example, the same powder used in the production of the molded bodies 51 and 53. For example, tungsten carbide powder can be used as the conductive powder. For example, cellulose-based binders (ethyl cellulose, etc.), acrylic-based binders (polymethyl methacrylate, etc.), and vinyl-based binders (polyvinyl butyral, etc.) can be used as binders. For example, terpineol can be used as a solvent. Printing methods can include, for example, screen printing. Printing is performed multiple times. Therefore, each precursor 66 and 64 forms a multilayer structure. In addition, the resistive heating element precursor 66 is printed in a stepped manner along the end face 66a in the length direction (see reference). Figure 6 The printed paste droops at the end, thus the final end face 66a becomes an inclined surface rather than a step. The end face 66a is preferably inclined relative to the surface of the lower pre-burned body 61, with an inclination angle δ of 45° or less. The electrostatic electrode precursor 64 is not shown, but it is similarly printed in a stepped manner. In this case, the printed paste also droops at the end, thus the final end face becomes an inclined surface rather than a step.

[0063] [4] Formation of grooves (refer to) Figure 5 (D) and Figures 7-9 )

[0064] A groove 67 is formed in the resistive heating element precursor 66 disposed on one side of the lower pre-burned body 61. The depth of the groove 67 is preferably less than half the depth of the resistive heating element precursor 66. Using... Figure 7 The picosecond laser processing machine 30 shown forms a groove 67. While driving the motors of the current mirror and the stage, the picosecond laser processing machine 30 irradiates the resistive heating element precursor 66 with a laser 32 along its length, thereby forming a groove 68. The width of the groove 68 (the width of the groove formed in one pass) is not particularly limited, but is preferably 10 to 100 μm, more preferably 20 to 60 μm. The picosecond laser processing machine 30 arranges multiple grooves 68 in an overlapping manner along the width direction of the resistive heating element precursor 66, thereby forming the groove 67. Regarding the laser 32, the energy is highest at the center of the irradiation position, and decreases towards the outermost position. Therefore, the cross-section of the formed groove 68 becomes as shown... Figure 8The shape shown is close to a sinusoidal curve. If the pitch of the line grooves 68 is set to be half the width of the line grooves 68, the cross section of the laser 32 when the next line groove 68 is formed from the present line groove 68 is shown by a dashed line in Figure 8 , the cross section of the laser 32 when the next line groove 68 is formed is shown by a single-dot chain line in Figure 8 , and the cross section of the laser 32 when the next line groove 68 is formed is shown by a double-dot chain line in Figure 8 . Thus, if the formation of all the line grooves 68 described above is completed, a recess 67 whose bottom surface is close to substantially flat is obtained as shown in Figure 9 . The recess 67 is a collection of the line grooves 68. The side wall surface 67a of the recess 67 is inclined with respect to the surface of the lower pre-fired body 61. The inclination angle β (refer to Figure 9 ) of the side wall surface 67a of the recess 67 with respect to the surface of the lower pre-fired body 61 is preferably 45° or less. In addition, if the processability of the laser 32 is taken into consideration, the inclination angle β is preferably 18° or more. The inclination angle β varies depending on the output power of the laser 32 and the number of times of processing by the laser 32 (the number of times of irradiation of the laser 32 to the same site). At this time, it is preferable that the inclination angle β be larger than the inclination angle δ, in other words, that the inclination angle δ be more gradual than the inclination angle β.

[0065] In forming the recess 67, first, the thickness distribution of the resistance heating element precursor 66 before the recess 67 is formed is measured using a laser displacement meter. This measurement is performed at a plurality of measurement points predetermined along the center line of the resistance heating element precursor 66. The difference (difference in thickness) between the target value of the thickness predetermined at each measurement point and the measured value of the thickness is found. The target value of the thickness is set based on the target value of the resistance when the resistance heating element precursor 66 is fired to produce the resistance heating element 16. Then, based on the difference in thickness of a certain measurement point, the number of line grooves 68 formed in the interval from the measurement point to its adjacent measurement point is determined. The depth of the line groove 68 is a predetermined value. Thus, by varying the number of line grooves 68, the width of the recess 67 is varied, and the cross-sectional area of the recess 67 or even the cross-sectional area of the resistance heating element precursor 66 is varied. That is, the recess 67 is formed so that the cross-sectional area of the resistance heating element precursor 66 at the plurality of measurement points is a target cross-sectional area predetermined for each measurement point.

[0066] [5] Production of the laminate (refer to Figure 5 (E))

[0067] The alumina powder is layered on the surface of the lower pre-fired body 61 on which the resistance heating element precursor 66 is provided in a manner so as to cover the resistance heating element precursor 66, and the upper pre-fired body 63 is layered on the alumina powder in a manner so as to contact the alumina powder on the surface on which the electrostatic electrode precursor 64 is provided, and molding is performed to obtain a layered body 50. The layered body 50 has a structure in which the alumina powder layer 62 is interposed between the upper and lower pre-fired bodies 61, 63. As the alumina powder, the same powder as that used when the molded bodies 51, 53 are produced can be used.

[0068] [6] Hot-pressing (see Figure 5 (F))

[0069] The obtained layered body 50 is subjected to hot-pressing while a pressure is applied in the thickness direction. At this time, the layered body 50 is blocked by a mold and thus does not expand in the radial direction, and is compressed in the thickness direction. The compression rate varies depending on the pressing pressure, and is, for example, 30 to 70%. Accordingly, the resistance heating element precursor 66 is fired to become the resistance heating element 16, the electrostatic electrode precursor 64 is fired to become the electrostatic electrode 14, and the pre-fired bodies 61, 63 and the alumina powder layer 62 are sintered to be integrated as the ceramic substrate 12. As a result, the electrostatic chuck heater 10 is obtained. In the hot-pressing, the pressing pressure is preferably 30 to 300 kgf / cm2 2 , more preferably 50 to 250 kgf / cm2 2 , at least at the maximum temperature (firing temperature). In addition, the maximum temperature can be appropriately set depending on the kind, particle diameter, etc. of the ceramic powder, and is preferably set to a range of 1000 to 2000°C. The atmosphere can be appropriately selected from an atmospheric atmosphere, an inert atmosphere, and a vacuum atmosphere.

[0070] Here, the correspondence between the constituent elements of the present embodiment and the constituent elements of the present application is made clear. The electrostatic chuck heater 10 of the present embodiment corresponds to the ceramic heater of the present application. In addition, the formation of the resistance heating element precursor (see Figure 5 (C) and Figure 6 ) of the present embodiment corresponds to the process (a) of the present application, the formation of the grooves (see Figure 5 (D) and Figures 7-9 ) corresponds to the process (b), the production of the layered body (see Figure 5 (E)) corresponds to the process (c), the hot-pressing (see Figure 5 (F)) corresponds to the process (d), the pre-fired body 61 corresponds to the first ceramic fired layer, and the alumina powder layer 62 corresponds to the second ceramic unfired layer.

[0071] In the above-described embodiment, the cross-sectional area of the resistance heat generating body precursor 66 (and the resistance of the resistance heat generating body 16) is adjusted by forming the groove 67 in the resistance heat generating body precursor 66. At this time, the groove 67 is formed so that the side wall surface 67a of the groove 67 is inclined with respect to the surface of the lower portion of the pre-fired body 61. When the laminated body 50 is subjected to heat press firing, since the side wall surface 67a of the groove 67 is inclined, a pressure is applied between the side wall surface 67a of the groove 67 and the alumina powder included in the alumina powder layer 62, and the laminated body 50 is fired in a state in which they are in close contact. According to this, in the electrostatic chuck heater 10, it is possible to prevent a gap from being generated between the side wall surface 17a of the groove 17 and the ceramic substrate 12, and it is possible to improve the adhesion strength between the side wall surface 17a of the groove 17 and the ceramic substrate 12. Therefore, the thermal conductivity and the heat uniformity of the electrostatic chuck heater 10 obtained become good.

[0072] In addition, if the inclination angle β of the side wall surface 67a of the groove 67 with respect to the surface of the pre-fired body 61 is 45° or less, it is possible to reliably prevent a gap from being generated between the side wall surface 17a of the groove 17 of the resistance heat generating body 16 and the ceramic substrate 12 of the electrostatic chuck heater 10. If the processability (for example, the number of times of processing by laser, etc.) is considered, the inclination angle β is preferably 18° or more. This is because if the inclination angle β is too small, the depth of the groove 17 formed by one laser process becomes shallow, and therefore, in order to make the groove 17 a prescribed depth, the number of processes increases and the processing time becomes long.

[0073] Further, the groove 67 is formed so that the cross-sectional area at each of a plurality of measurement points determined in the length direction of the resistance heat generating body precursor 66 is a predetermined target cross-sectional area. Therefore, it is possible to determine the shape of the groove 67 without measuring the resistance of the resistance heat generating body precursor 66.

[0074] The depth of the groove 67 is preferably one-half or less of the thickness of the resistance heat generating body precursor 66. According to this, compared to a case in which the depth of the groove 67 is too deep, it is easier to prevent a gap from being generated between the side wall surface 17a of the groove 17 and the ceramic substrate 12 of the electrostatic chuck heater 10.

[0075] Further, the end surface 66a of the resistance heating element precursor 66 along the longitudinal direction is inclined with respect to the surface of the calcined body 61. Therefore, it is possible to prevent a gap from being generated between the end surface 16a of the resistance heating element 16 of the electrostatic chuck heater 10 along the longitudinal direction and the ceramic substrate 12, and it is possible to improve the adhesion strength between the end surface 16a and the ceramic substrate 12. Therefore, the heat conductivity and the heat uniformity of the electrostatic chuck heater 10 obtained become better. In particular, if the inclination angle δ of the end surface of the resistance heating element precursor 66 with respect to the surface of the calcined body 61 is 45° or less, it is possible to reliably prevent a gap from being generated between the end surface 16a of the resistance heating element 16 along the longitudinal direction and the ceramic substrate 12.

[0076] When the groove 67 is formed, it is preferable that the inclination angle β of the side wall 67a of the groove 67 be larger than the inclination angle δ of the end surface 66a of the resistance heating element precursor 66, in other words, that the inclination angle δ be more gradual than the inclination angle β. The height of the resistance heating element precursor 66 is larger than the depth of the groove 67. Therefore, by making the inclination of the end surface 66a of the resistance heating element precursor 66 more gradual, it is possible to further prevent a gap from being generated between the end surface 16a of the resistance heating element 16 of the electrostatic chuck heater 10 and the ceramic substrate 12.

[0077] Further, for the electrostatic chuck heater 10, the side wall surface 17a of the groove 17 is inclined with respect to the surface of the ceramic substrate 12, and there is no gap between the side wall surface 17a of the groove 17 and the ceramic substrate 12. Therefore, the heat conductivity and the heat uniformity of the electrostatic chuck heater 10 become good. The inclination angle α of the side wall surface 17a of the groove 17 with respect to the surface of the ceramic substrate 12 is preferably 27° or less. In addition, the inclination angle α is preferably 10° or more. In order to more reliably prevent a gap from being generated between the side wall surface 17a of the groove 17 and the ceramic substrate 12, it is preferable that the width of the groove 17 be set to be the depth of the groove 17 or more.

[0078] In addition, for the electrostatic chuck heater 10, the opening edge 17b of the groove 17 is a shape obtained by chamfering. Therefore, compared to a case where the opening edge of the groove 17 has an angle, a crack starting from the opening edge 17b of the groove 17 is less likely to occur. Note that even if the opening edge of the groove 67 before the heat-pressing firing has an angle, the opening edge 17b of the groove 17 after the heat-pressing firing becomes a shape obtained by chamfering. The depth of the groove 17 is preferably half or less of the thickness of the resistance heating element 16.

[0079] Further, for the electrostatic chuck heater 10, the end surface 16a of the resistance heat generating body 16 in the longitudinal direction is inclined with respect to the surface of the ceramic substrate 12, and there is no gap between the end surface 16a and the ceramic substrate 12. Therefore, the heat conductivity and the heat uniformity of the electrostatic chuck heater 10 become better. The inclination angle γ of the end surface 16a of the resistance heat generating body 16 in the longitudinal direction with respect to the surface of the ceramic substrate 12 is preferably 27° or less. The inclination angle γ is preferably smaller than the inclination angle α of the side surface 17a of the groove 17.

[0080] It should be noted that the present application is not limited to the above-described embodiments, and can be implemented in various forms as long as they belong to the technical scope of the present application.

[0081] For example, in the above-described embodiments, the electrostatic chuck heater 10 is exemplified as the ceramic heater, but a ceramic heater not having the electrostatic electrode 14 can be used. In this case, the green body 63 not having the upper portion of the electrostatic electrode precursor 64 can be used to produce the laminate 50, and the laminate 50 can be subjected to hot-press sintering, or the green body 63 of the upper portion can be omitted, and the laminate 50 can be subjected to hot-press sintering.

[0082] In the above-described embodiments, the alumina powder layer 62 is exemplified as the second ceramic green layer, but an alumina formed body layer or an alumina green sheet can be used instead of the alumina powder layer 62. The alumina formed body layer can be a dried formed body layer, or a formed body layer subjected to debinding after drying.

[0083] In the above-described embodiments, the pre-sintered body 61 is exemplified as the first ceramic sintered layer, but an alumina sintered body can be used instead of the pre-sintered body 61. Alternatively, a ceramic formed body layer or a ceramic green sheet can be used instead of the first ceramic sintered layer. The ceramic formed body layer can be a dried formed body layer, or a formed body layer subjected to debinding after drying.

[0084] In the above-described embodiments, the resistance heat generating body precursor 66 for forming the groove 67 is exemplified as a precursor obtained by printing a paste of the resistance heat generating body and drying it, but a precursor obtained by printing, drying, and then debinding, or a precursor obtained by printing, drying, debinding, and then pre-sintering (or sintering) can be used.

[0085] In the above-described embodiment, the resistance heating element 16 is obtained by wiring in a single stroke in a non-intersecting band shape on the entire ceramic substrate 12, but is not particularly limited thereto. For example, the ceramic substrate 12 can be divided into a plurality of sections, and a resistance heating element obtained by wiring in a single stroke in a non-intersecting band shape can be provided for each section. In this case, each resistance heating element can have the same structure as the above-described resistance heating element 16.

[0086] Embodiment

[0087] Hereinafter, an embodiment of the present application will be described. It should be noted that the following embodiment does not limit the present application in any way.

[0088] [Embodiment 1]

[0089] According to the above-described production example, the electrostatic chuck heater 10 (refer to Figure 5 ) was produced.

[0090] [1] Production of shaped bodies

[0091] An alumina powder (average particle diameter: 0.5 μm, purity: 99.7%) 100 parts by weight, magnesium oxide 0.04 parts by weight, a polycarboxylic acid copolymer 3 parts by weight as a dispersant, and a polybasic acid ester 20 parts by weight as a solvent were weighed, mixed using a ball mill (tumbler sieve) for 14 hours, and a slurry precursor was produced. To the slurry precursor, a gelling agent, i.e., 4,4'-diphenylmethane diisocyanate 3.3 parts by weight as an isocyanate, ethylene glycol 0.3 parts by weight as a polyol, and 6-dimethylamino-l-hexanol 0.1 parts by weight as a catalyst were added, mixed using a self-rotating stirrer for 12 minutes, and a slurry was obtained. The obtained slurry was cast into a molding die. Then, the slurry was gelled by allowing the gelling agent to chemically react in the molding die at 22°C for 2 hours, and demolding was performed. In this way, the upper and lower shaped bodies 51, 53 (refer to Figure 5 (A)) were obtained.

[0092] [2] Production of preforms

[0093] After the upper and lower shaped bodies 51, 53 were dried at 100°C for 10 hours, debinding was performed at a maximum temperature of 500°C for 1 hour, and further, preforming was performed at a maximum temperature of 820°C in an atmosphere for 1 hour, whereby the upper and lower preforms 61, 63 (refer to Figure 5 (B)) were obtained.

[0094] [3] Formation of resistance heating element precursor

[0095] Tungsten carbide powder (average particle size 1.5 μm) and alumina powder (average particle size 0.5 μm) were mixed at an alumina content of 10% by weight. Polymethyl methacrylate (PMMA) as a binder and terpineol as a solvent were added and mixed to prepare a paste. This paste is used for both the resistive heating element and the electrostatic electrode. Then, the resistive heating element was screen-printed multiple times with the paste on one side of the lower pre-burned body 61, and then dried to form a 100 μm thick resistive heating element precursor 66. Additionally, the electrostatic electrode was screen-printed multiple times with the paste on one side of the upper pre-burned body 63, and then dried to form an electrostatic electrode precursor 64 (see reference). Figure 5 (C) The tilt angle δ of the end face 66a of the resistive heating element precursor 66 is 10°. In reality, the end of the printed paste hangs down, therefore, the end face 66a is a tilted surface rather than a step. The tilt angle of the end face of the electrostatic electrode precursor 64 is also the same value.

[0096] [4] Formation of grooves

[0097] The thickness distribution of the resistive heating element precursor 66 was measured using a laser displacement meter. Based on the measurement results, a pitot-second laser processing machine 30 was used to form a groove 67 on the surface of the resistive heating element precursor 66. The laser processing conditions were as follows: laser output power 20W, processing speed 2000mm / sec, and processing times 2. The shape of the formed groove 67 was measured. The results are shown below. Figure 10 .Depend on Figure 10 It can be seen that the depth of groove 67 is 20μm, and the inclination angle β of the sidewall 67a of groove 67 is 34°.

[0098] Here, the method for calculating the tilt angle β is explained. First, as... Figure 11 As shown, an object range of 0.5 mm is defined along the width direction, including the sidewall surface 67a which serves as an inclined surface. At this time, the bottom surface of the resistive heating element precursor 66 is calibrated to be approximately horizontal, and the center of the object range is approximately aligned with the center of the sidewall surface 67a. The height of the resistive heating element precursor 66 is measured at 2.5 μm intervals along the width direction over the entire area of ​​this object range. The height is measured using a stylus probe. A histogram is then created with the height of the resistive heating element precursor 66 on the horizontal axis and degrees on the vertical axis. The height data interval is 1 μm. An example of a histogram is shown below. Figure 12The histogram has a first group of low heights and a second group of high heights. The first group is a group of heights of the bottom surface of the groove 67, and the second group is a group of heights of the top surface of the resistance heater precursor 66 (a portion where the groove 67 is not provided). In the histogram, the value with the highest degree (the most frequent value) in the first group is taken as the bottom surface height HL of the groove 67, and the value with the highest degree (the most frequent value) in the second group is taken as the top surface height HU of the resistance heater precursor 66. In addition, the value obtained by subtracting HL from HU is set as the depth D of the groove 67. Then, the value obtained by adding 0.1D to HL is set as the lower limit value, and the value obtained by subtracting 0.1D from HU is set as the upper limit value, and the height measured at an interval of 2.5 μm between the lower limit value and the upper limit value of the side wall surface 67a is used to find a regression straight line of the side wall surface 67a, and the angle formed by the regression straight line and the horizontal line (the abscissa axis) is set as the inclination angle β. Note that the inclination angle δ of the end surface 66a of the resistance heater precursor 66 before is also solved in the same manner. However, when solving the inclination angle δ, the range of the object is set to 1.5 mm instead of 0.5 mm. Figure 10

[0099] [5] Production of the laminate

[0100] On the surface of the pre-sintered body 61 where the resistance heater precursor 66 is provided, alumina powder is laminated in a manner so as to cover the resistance heater precursor 66, and on the alumina powder, the pre-sintered body 63 is laminated in a manner so as to contact the surface where the electrostatic electrode precursor 64 is provided with the alumina powder, and molding is performed to obtain a laminate 50.

[0101] [6] Hot-press sintering

[0102] Hot-press sintering is performed on the obtained laminate 50. By this, the resistance heater precursor 66 is sintered to become a resistance heater 16 with a thickness of 50 μm, the electrostatic electrode precursor 64 is sintered to become an electrostatic electrode 14, and the pre-sintered bodies 61 and 63 and the alumina powder layer 62 are sintered to be integrated to become a ceramic substrate 12, and an electrostatic chuck heater 10 is obtained. The hot-press sintering is performed under a vacuum atmosphere at a pressure of 250 kgf / cm 2 , at a maximum temperature of 1600°C for 2 hours. Then, the surface of the ceramic sintered body is subjected to planar grinding processing using a diamond grindstone so that the thickness of the electrostatic electrode 14 to the wafer loading surface 12a is 350 μm.

[0103] [evaluation]

[0104] ​The appearance of the ceramic substrate (alumina substrate) 12 of the electrostatic chuck heater 10 obtained was observed, and as a result, no portion where a color tone was different was observed. In addition, from the SEM photograph of the cross section of the electrostatic chuck heater 10 obtained (magnification 150 times, number of pixels 165,000 pixels or more), the depth of the groove 17 was 10 μm, and the inclination angle α of the side wall surface 17a of the groove 17 was 18°. The depth of the groove 17 and the inclination angle α were obtained in the same manner as the depth D and the inclination angle β of the groove 67 of Example 1. In addition, in the SEM photograph, no gap was observed between the side wall surface 17a of the groove 17 and the ceramic substrate (alumina substrate) 12. The inclination angle γ of the end surface 16a of the resistance heater 16 in the longitudinal direction was 5°. The inclination angle γ was obtained in the same manner as the inclination angle δ of the end surface of the resistance heater 66 of Example 1. The inclination angle of the end surface of the electrostatic electrode 14 was also 5°. No gap was observed between each end surface and the ceramic substrate 12.

[0105] [Example 2]

[0106] The number of times of processing of the laser processing conditions of Example 1 described above was set to one time, and otherwise, the electrostatic chuck heater 10 was produced in the same manner as Example 1. The depth of the groove 67 of the resistance heater precursor 66 was 10 μm, and the inclination angle β was 18°, and the inclination angle δ of the end surface 66a of the resistance heater precursor 66 and the inclination angle of the end surface of the electrostatic electrode precursor 64 were 10°. The SEM photograph of the cross section of the electrostatic chuck heater 10 was observed in the same manner as Example 1, and as a result, the depth of the groove 17 was 5 μm, and the inclination angle α of the side wall surface 17a of the groove 17 was 10°. No gap was observed between the side wall surface 67a of the groove 67 and the ceramic substrate 12. The inclination angle γ of the end surface of the resistance heater 16 in the longitudinal direction was 5°. The inclination angle of the end surface of the electrostatic electrode 14 was also 5°. No gap was observed between each end surface and the ceramic substrate 12. Note that each inclination angle was obtained in the same manner as Example 1.

[0107] [Example 3]

[0108] The number of times of processing of the laser processing conditions of Example 1 described above was set to 3, and otherwise, the electrostatic chuck heater 10 was produced in the same manner as in Example 1. The depth of the groove 67 of the resistance heat generating body precursor 66 was 30 μm, the inclination angle β was 45°, the inclination angle δ of the end surface 66a of the resistance heat generating body precursor 66, and the inclination angle of the end surface of the electrostatic electrode precursor 64 were 10°. The SEM photograph of the cross section of the electrostatic chuck heater 10 was taken and observed in the same manner as in Example 1, and as a result, the depth of the groove 17 was 15 μm, and the inclination angle α of the side wall surface 17a of the groove 17 was 27°. No gap was observed between the side wall surface 17a of the groove 17 and the ceramic substrate 12. The inclination angle γ of the end surface of the resistance heat generating body 16 along the length direction was 5°. The inclination angle of the end surface of the electrostatic electrode 14 was also 5°. No gap was observed between each end surface and the ceramic substrate 12. It should be noted that each inclination angle was solved in the same manner as in Example 1.

[0109] The main results of Examples 1 to 3 are shown in Table 1.

[0110] [Table 1]

[0111]

[0112] [Examples 4 and 5]

[0113] In Example 4, the inclination angle δ of the end surface 66a was set to 18°, and otherwise, the electrostatic chuck heater 10 was produced in the same manner as in Example 1 described above. The inclination angle γ of the end surface 16a of the resistance heat generating body 16 along the length direction was 10°. In Example 5, the inclination angle δ of the end surface 66a was set to 45°, and otherwise, the electrostatic chuck heater 10 was produced in the same manner as in Example 1 described above. The inclination angle γ of the end surface 16a of the resistance heat generating body 16 along the length direction was 26°. In Examples 4 and 5, no gap (abnormality of heat conduction caused thereby) was confirmed in the vicinity of the end surface 16a of the resistance heat generating body 16.

[0114] This application claims priority based on Japanese Patent Application No. 2020-030724 filed on February 26, 2020, the entire contents of which are incorporated herein by reference.

[0115] Industrial Applicability

[0116] The ceramic heater of the present application can be utilized as, for example, a component for a semiconductor manufacturing apparatus.

[0117] Explanation of Symbols

[0118] 10 electrostatic chuck heater, 12 ceramic substrate, 12a wafer mounting surface, 14 electrostatic electrode, 16 resistance heat generating body, 16a end surface, 17 groove, 17a side wall surface, 17b opening edge, 18, 20 terminal portion, 22 cooling plate, 24 coolant passage, 26 adhesive layer, 30 picosecond laser processing machine, 32 laser, 50 layered body, 51, 53 shaped body, 61, 63 pre-fired body, 62 alumina powder layer, 64 electrostatic electrode precursor, 66 resistance heat generating body precursor, 66a end surface, 67 groove, 67a side wall surface, 68 wire groove.

Claims

1. A method of making a ceramic heater, comprising: The method comprises the following steps: (a) forming a resistance heating element or a precursor thereof in a predetermined pattern on a surface of a first ceramic fired layer or an unfired layer; (b) irradiating the resistance heating element or the precursor thereof with a laser to form a groove along a length direction of the resistance heating element or the precursor thereof; (c) disposing a second ceramic unfired layer on the surface of the first ceramic fired layer or the unfired layer in a manner of covering the resistance heating element or the precursor thereof to obtain a laminate; (d) performing hot-pressing firing on the laminate to obtain a ceramic heater having the resistance heating element implanted in an interior of a ceramic substrate, In the step (b), the groove is formed in a manner that a side wall surface of the groove is inclined with respect to the surface of the first ceramic fired layer or the unfired layer and an inclination angle of the side wall surface of the groove with respect to the surface of the first ceramic fired layer or the unfired layer is 45° or less.

2. The method of manufacturing the ceramic heater according to claim 1, wherein In the step (b), the groove is formed in a manner that cross-sectional areas at a plurality of measurement points determined along the length direction of the resistance heating element or the precursor thereof are respectively the target cross-sectional area.

3. The method of manufacturing the ceramic heater according to claim 1 or 2, wherein In the step (b), a depth of the groove is half or less of a thickness of the resistance heating element or the precursor thereof.

4. The method of manufacturing the ceramic heater according to claim 1 or 2, wherein In the step (a), the resistance heating element or the precursor thereof is formed in a manner that an end surface of the resistance heating element or the precursor thereof along the length direction is inclined with respect to the surface of the first ceramic fired layer or the unfired layer.

5. The method of manufacturing the ceramic heater according to claim 4, wherein In the step (a), the resistance heating element or the precursor thereof is formed in a manner that an inclination angle of the end surface of the resistance heating element or the precursor thereof along the length direction with respect to the surface of the first ceramic fired layer or the unfired layer is 45° or less.

6. The method of manufacturing the ceramic heater according to claim 4, wherein In the step (b), the inclination angle of the side wall surface of the groove is made larger than the inclination angle of the end surface of the resistance heating element or the precursor thereof along the length direction.

7. The method of manufacturing the ceramic heater according to claim 5, wherein In the step (b), the inclination angle of the side wall surface of the groove is made larger than the inclination angle of the end surface of the resistance heating element or the precursor thereof along the length direction.

8. A ceramic heater having a resistance heating element implanted in an interior of a ceramic substrate, The ceramic heater is characterized by comprising: a groove provided on a surface of the resistance heating element along a length direction of the resistance heating element; and a side wall surface of the groove inclined with respect to a surface of the ceramic substrate, an inclination angle of the side wall surface of the groove with respect to the surface of the ceramic substrate is 27° or less, there is no gap between the side wall surface of the groove and the ceramic substrate.

9. The ceramic heater according to claim 8, wherein an opening edge of the groove is chamfered.

10. The ceramic heater according to claim 8 or 9, wherein a depth of the groove is less than half of a thickness of the electric resistance heat generating body.

11. The ceramic heater according to claim 8 or 9, wherein an end surface of the electric resistance heat generating body in a length direction is inclined with respect to a surface of the ceramic substrate, and there is no gap between the end surface and the ceramic substrate.

12. The ceramic heater according to claim 11, wherein an inclination angle of the end surface of the electric resistance heat generating body in the length direction with respect to the surface of the ceramic substrate is 27° or less.

13. The ceramic heater according to claim 11, wherein the inclination angle of the end surface of the electric resistance heat generating body in the length direction is smaller than an inclination angle of a side surface of the groove.

14. The ceramic heater according to claim 12, wherein the inclination angle of the end surface of the electric resistance heat generating body in the length direction is smaller than the inclination angle of the side surface of the groove.

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