JP2005085657A - Ceramic heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain a cooling spot from being caused on a heating surface. <P>SOLUTION: This ceramic heater is provided with: a ceramic substrate 21 with a resistance heating element 23 embedded; and a power-feeding terminal 27 having one end connected to the heating element 23 and the other end formed so as to be exposed to the outside from a surface, that is, the bottom surface opposite to the heating surface of the ceramic substrate 21; and the diameter (d) of the power-feeding terminal 27 is smaller than the width W of the resistance heating element. In the ceramic heater, the heat capacity of the power-feeding terminal 27 is small and the heat quantity of the heating element 23 is hardly radiated as compared with one where the diameter (d) of the power-feeding terminal is larger than the width W of the resistance heating element, and the power-feeding terminal 27 itself generates heat by carrying a current. Therefore, a cooling spot is prevented from being caused on the heating surface of the ceramic substrate 21. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a ceramic heater.

Conventionally, as a ceramic heater, what is installed in a semiconductor manufacturing apparatus using a corrosive gas is known. As this type of ceramic heater, as shown in FIG. 10, a tungsten-based resistance heating element 303 is embedded in a spiral shape inside a disk-shaped ceramic substrate 301, and power supply terminals 305 are provided at both ends of the resistance heating element 303. There is known a technique in which a conductive member 307 is connected via a wire and heated by supplying electric power from the conductive member 307 (see Patent Document 1).
Japanese Patent No. 2518962

  However, in the ceramic heater disclosed in Patent Document 1, the conductive member 307 is connected via the columnar power supply terminal 305 having a diameter larger than the width of the spiral resistance heating element 303. There is a problem that heat generated by energization is taken by the power supply terminal 305 and a cooling spot 309 is generated on the heating surface of the ceramic substrate 301.

  This invention is made | formed in view of such a subject, and it aims at providing the ceramic heater which suppresses that a cooling spot generate | occur | produces on a heating surface.

  The ceramic heater of the present invention employs the following means in order to achieve the above object. That is, the ceramic heater of the present invention has a ceramic substrate in which a resistance heating element is embedded, and one end connected to the resistance heating element and the other end exposed from the surface opposite to the heating surface of the ceramic substrate. And the diameter of the power supply terminal is smaller than the width of the resistance heating element.

  In this ceramic heater, the diameter of the power supply terminal is smaller than the width of the resistance heating element, compared to the one where the diameter of the power supply terminal is larger than the width of the resistance heating element. It is hard to steal. Therefore, generation of a cooling spot on the heating surface can be suppressed.

  In the ceramic heater of the present invention, it is preferable that the power supply terminal generates heat when energized. By so doing, the power feeding terminal itself generates heat, so that the generation of cooling spots can be effectively suppressed. In light of technical common sense, it is preferable not to generate heat at the power supply terminal because there is no power loss, but it is surprising that the occurrence of cooling spots generated on the heating surface can be effectively suppressed by performing the reverse of this common technical knowledge. The effect was acquired.

  In the ceramic heater of the present invention, it is preferable that W / d is 1.1 to 10, where W is the width of the resistance heating element and d is the diameter of the power supply terminal. This is because if W / d is less than 1.1, the generation of cooling spots may not be sufficiently suppressed, and if W / d exceeds 10, there is a tendency for hot spots to be generated due to heat generated by the power supply terminals themselves.

  In the ceramic heater of the present invention, the resistance heating element preferably has a width of 1 to 30 mm. If the width of the resistance heating element is less than 1 mm, it becomes difficult to uniformly heat the heating surface, so that the temperature uniformity of the heating surface tends to decrease, and if it exceeds 30 mm, the resistance heating element is excessively curved on the inner periphery when the resistance heating element is curved. This is because current flows and the amount of heat generation increases, and the temperature uniformity of the heating surface tends to decrease. In particular, the width of the resistance heating element is preferably 5 to 25 mm. Moreover, it is preferable that the diameter of the power supply terminal is 0.5 to 20 mm (provided that the condition is smaller than the width of the resistance heating element). If the thickness is less than 0.5 mm, hot spots tend to be generated, and if it exceeds 20 mm, the generation of cooling spots may not be sufficiently suppressed. In particular, the diameter of the power supply terminal is preferably 1 to 10 mm.

  In the ceramic heater of the present invention, a projection image when the power feeding terminal is virtually projected onto the heating surface may be included in a projection image when the resistance heating element is virtually projected onto the heating surface. By so doing, the generation of cooling spots can be more effectively suppressed.

  In the ceramic heater of the present invention, it is preferable that at least one layer of the resistance heating element is formed at a position from the surface opposite to the heating surface of the ceramic substrate to 60% of the thickness of the substrate. By so doing, the heat of the resistance heating element diffuses while propagating to the heating surface of the ceramic substrate, and the temperature on the heating surface tends to be uniform.

  In the ceramic heater of the present invention, it is preferable that the resistance heating element is mainly composed of carbide ceramic, the ceramic substrate is mainly composed of nitride ceramic, and the power supply terminal is mainly composed of refractory metal. When a metal (for example, W or Mo) is used as the main component of the resistance heating element, the metal rapidly increases the lattice vibration as the temperature rises, preventing the free movement of electrons and increasing the volume resistivity. When the voltage is constant, the current decreases and the temperature rise becomes difficult. On the other hand, since the volume resistivity of conductive ceramics, particularly carbide ceramics, decreases as the temperature increases, a large current can be input at a high temperature (300 to 1000 ° C.), and the temperature can be easily increased. Therefore, it is preferable that the resistance heating element is mainly composed of carbon or carbide ceramic, particularly carbide ceramic. The ceramic substrate is preferably composed mainly of a nitride ceramic. This is because nitride ceramics are excellent in heat resistance and mechanical properties, are excellent in corrosion resistance and durability against halogen-based corrosive gas and plasma, have high thermal conductivity, and excellent temperature followability. Further, the volume resistivity of nitride ceramics at a high temperature is sufficiently higher than the volume resistivity of carbide ceramics at a high temperature, so there is no possibility of causing an electrical short circuit through the ceramic substrate at a high temperature. The power supply terminal is preferably composed mainly of a refractory metal such as W or Mo. This is because these refractory metals are excellent in adhesion to the nitride ceramic, which is the main component of the ceramic substrate, and have a thermal expansion coefficient close to that of the nitride ceramic, so that cracks due to thermal shock are unlikely to occur.

  In the ceramic heater of the present invention, the power supply terminal has a thread on the outer periphery, and is screwed into a screw hole formed on a surface opposite to the heating surface of the ceramic substrate and mechanically joined, and has one end. It is preferable to be chemically joined to the resistance heating element by brazing. In this case, the power supply terminal is fixed to the ceramic substrate by mechanical bonding and chemical bonding, and therefore, there is no fear of dropping out compared to the case of only chemical bonding. Here, one end of the power supply terminal may be brazed directly to the resistance heating element, or may be brazed via a pad or a conductor layer.

  The ceramic heater of the present invention can be used for an apparatus using a corrosive gas, for example, a plasma generator. When used in a plasma generator, a plasma generating electrode may be embedded in a ceramic substrate together with a resistance heating element.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 is a schematic explanatory view of a plasma CVD apparatus 10, FIG. 2 is a partial cross-sectional view of a susceptor 20, FIG. 3 is an enlarged view of an essential part of FIG. 2 (enlarged view near a power supply terminal), and FIG. It is sectional drawing.

  As shown in FIG. 1, the plasma CVD apparatus 10 includes a susceptor 20 (corresponding to a ceramic heater of the present invention) and a shower head 60 in a reaction chamber 12. The susceptor 20 includes a disk-shaped ceramic substrate 21 on which an object 18 such as a silicon wafer is placed on the upper surface, and a hollow ceramic sleeve 41 extending downward from the center of the lower surface of the ceramic substrate 21. Among these, the ceramic substrate 21 is embedded with a resistance heating element 23 for heating the workpiece 18 and a lower electrode 33 (upper and lower two layers) for plasma generation. The resistance heating element 23 is connected to the positive electrode and the negative electrode of the power supply 67 via the conductive members 29 and 29. On the other hand, the peripheral edge of the upper opening of the ceramic sleeve 41 is diffusion bonded to the ceramic substrate 21. The ceramic sleeve 41 has a radially outward flange 42 at the periphery of the lower opening, and the flange 42 is fastened to the bottom surface of the reaction chamber 12 via an O-ring 43. For this reason, the inside of the ceramic sleeve 41 and the inside of the reaction chamber 12 are completely isolated. The shower head 60 is disposed at a position parallel to and opposed to the ceramic substrate 21 and introduces a reaction gas supplied from a reaction gas source (not shown) through the valve 61 into the reaction chamber 12 in a shower shape. The shower head 60 also serves as an upper electrode 63 for generating plasma. The upper electrode 63 and the two-layer lower electrode 33 are connected so that a high frequency 65 is applied. Further, the reaction chamber 12 is provided with an exhaust port 14, and a vacuum pump is connected to the exhaust port 14 via an adjustment valve 16.

  Next, the ceramic substrate 21 will be described in detail with reference to FIG. As described above, the ceramic substrate 21 has the resistance heating element 23 for heating the object 18 to be processed and the lower electrode 33 for plasma generation embedded therein, as well as a power supply terminal 27 for supplying power to the resistance heating element 23. And a lifter pin 51 inserted into the lifter pin insertion hole 50, a temperature measuring element 45 inserted into the bottomed hole 46, and the like. This ceramic substrate 21 is composed mainly of aluminum nitride and yttrium oxide, and is diffusion bonded to the peripheral edge of the upper opening of the hollow ceramic sleeve 41 mainly composed of aluminum nitride. The upper surface (heating surface) of the ceramic substrate 21 is processed to have a surface roughness Ra of 1.0 μm or less. On the upper surface, a plurality of convex portions 21 a that support the object to be processed 18 are formed. The convex portion 21 a is formed by fitting a substantially spherical support body into a concave portion formed on the upper surface of the ceramic substrate 21. The height of the convex portion 21a is set so that the distance between the workpiece 18 supported by the convex portion 21a and the upper surface of the ceramic substrate 21 is 10 to 2000 μm.

  The resistance heating element 23 is embedded in the ceramic substrate 21. The resistance heating element 23 is a flat tungsten carbide plate-like member having a width of 1 to 30 mm (5 to 25 mm in this embodiment) and a thickness of 1 to 50 μm. In addition, the resistance heating element 23 has one end 23a disposed substantially at the center of the ceramic substrate 21, and the resistance heating element 23 is wired from the end 23a to the entire surface of the ceramic substrate 21 in a so-called one-stroke manner. Finally, the other end 23a is arranged near one end 23a.

  2 to 4, the power supply terminal 27 is attached so that the upper end is connected to the resistance heating element 23 and the lower end is exposed to the outside from the surface opposite to the heating surface of the ceramic substrate 21, that is, the lower surface. ing. The power supply terminal 27 is made of tungsten and has a substantially cylindrical outer shape. The diameter of the power supply terminal 27 is smaller than the width of the resistance heating element 23. Specifically, the diameter d is determined so that W / d is in the range of 1.1 to 10, where d is the diameter of the power supply terminal 27 and W is the width of the resistance heating element 23. For example, if the width W of the resistance heating element 23 is 10 mm, the diameter d of the power supply terminal 27 is set in the range of 1 mm to 9.1 mm. The power supply terminal 27 is brazed with a conductor filling layer 26 and a brazing material 28 formed to extend downward from the end 23 a of the resistance heating element 23. The conductor filling layer 26 is formed in a substantially cylindrical shape, and its diameter is smaller than the width of the resistance heating element 23 and the diameter of the power supply terminal 27. The power supply terminal 27 is a set screw type terminal having a screw thread 27 a formed on the outer periphery, and is screwed into a screw hole 22 provided on the lower surface of the ceramic substrate 21. As described above, the power supply terminal 27 is not only chemically bonded to the conductor filling layer 26 connected to the resistance heating element 23 by the brazing material 28 but also mechanically connected by screws. Furthermore, a screw hole 27b that opens downward is formed in the power supply terminal 27 along the axis. A rod-like nickel conductive member 29 is screwed into the screw hole 27b. That is, a male screw 29 b is formed at the upper end of the conductive member 29, and this male screw 29 b is screwed into a screw hole 27 b of the power supply terminal 27, that is, a female screw. The two conductive members 29 and 29 are connected to the positive electrode and the negative electrode of the power source 67 (see FIG. 1), respectively, and serve to supply power from the power source 67 to the resistance heating element 23.

  Examples of the brazing material 28 include noble metals such as gold, silver, platinum, and palladium; metals such as lead, tungsten, molybdenum, and nickel, or alloys thereof, and conductive ceramics such as carbon, tungsten, and molybdenum carbides. Can be mentioned. Further, the material constituting the conductor filling layer 26 is not particularly limited. For example, noble metals such as gold, silver, platinum, and palladium; metals such as lead, tungsten, molybdenum, and nickel, or alloys thereof, carbon, tungsten, Examples thereof include conductive ceramics such as molybdenum carbide.

  The lower electrode 33 is an electrode for generating plasma and is embedded in the ceramic substrate 21. The lower electrode 33 is a mesh disk made of conductive ceramic. In the present embodiment, the lower electrode 33 is formed in two upper and lower layers. This is to reduce the amount of current flowing through the electrode (allowable current) and suppress the heat generation of the electrode. The conductive member 35 is joined to both the lower electrodes 33 so that the high frequency 65 can be applied between the lower electrodes 33. Here, in joining the lower electrode 33 and the conductive member 35, the same configuration as the joining of the resistance heating element 23 and the conductive member 29 is adopted. That is, a high frequency application terminal 37 having the same structure as that of the power supply terminal 27 is brazed to the conductor filling layer 36 formed to extend downward from the lower electrode 33 and is screwed into a screw hole provided in the ceramic substrate 21. ing. The high-frequency application terminal 37 is formed with a screw hole that opens downward along the axis, and the conductive member 35 is screwed into the screw hole.

  In the ceramic substrate 21, lifter pin insertion holes 50 penetrating in the vertical direction are provided at three apexes of an equilateral triangle having the same center as the disk-shaped ceramic substrate 21. These three places are all outside the ceramic sleeve 41. The lifter pin insertion hole 50 is inserted with a lifter pin 51 that is moved up and down by an operating mechanism (not shown). Also, the lifter pin 51 is connected to a workpiece (not shown) that carries the workpiece 18 into or out of the reaction chamber 12. 18 is received and delivered, and when performing this role, it extends upward from the upper surface of the ceramic substrate 21 and lifts the workpiece 18 from the convex portion 21a of the ceramic substrate 21, or the ceramic substrate. The workpiece 18 is placed below the upper surface of the substrate 21 and placed on the convex portion 21 a of the ceramic substrate 21. The lifter pin 51 is moved up and down by an actuator (motor, air cylinder, hydraulic cylinder, etc.) (not shown). In FIG. 1, the lifter pin insertion hole 50 and the lifter pin 51 are omitted.

  The temperature measuring element 45 measures the temperature of the ceramic substrate 21 and employs a sheath thermocouple in this embodiment. The temperature measuring element 45 is held in a state in which the tip is pressed against the bottom of the bottomed hole 46 provided on the lower surface of the ceramic substrate 21 by urging of a spring (not shown). A controller (not shown) feedback-controls energization to the resistance heating element 23 so that the temperature of the ceramic substrate 21 measured by the temperature measuring element 45 becomes a temperature set in advance by an operator. In FIG. 1, the temperature measuring element 45 and the bottomed hole 46 are omitted.

  Next, the operation of the plasma CVD apparatus 10 of this embodiment, that is, the operation of forming a film on the surface of the object 18 such as a silicon wafer will be briefly described. First, when an unprocessed object 18 that has been carried into the reaction chamber 12 by a transfer machine (not shown) is placed on the lifter pin 51 that extends upward from the upper surface of the ceramic substrate 21, the lifter pin 51 is moved downward from the upper surface. The workpiece 18 is placed on the convex portion 21 a of the ceramic substrate 21. Subsequently, the inside of the reaction chamber 12 is adjusted to a predetermined degree of vacuum (for example, 10 to 60000 Pa) by the adjusting valve 16, and the temperature measured by the temperature measuring element 45 is a predetermined temperature (for example, 300 to 600 ° C.). The object 18 is heated by energizing the resistance heating element 23 so that At this time, a current flows from the power source 67 through the conductive members 29 and 29 and the power supply terminals 27 and 27 to the resistance heating element 23. Subsequently, the valve 61 is opened, and a reaction gas is introduced into the reaction chamber 12 from the shower head 60 into the reaction chamber 12 by a mass flow controller (not shown). Then, a high frequency 65 is applied between the upper electrode 63 and the lower electrode 33 to turn the reaction gas into plasma and dissociate it into ions and electrons. Thereby, the dissociated ions cause a chemical reaction on the surface of the object to be processed 18 and a film is formed on the surface of the object to be processed 18.

  According to the susceptor 20 of the present embodiment described above, since the diameter d of the power supply terminal 27 is smaller than the width W of the resistance heating element 23, the heat capacity of the power supply terminal 27 is smaller and the resistance is smaller than that in which d is larger than W. It is difficult to take the heat amount of the heat generating element 23, and when the resistance heat generating element 23 is energized, the power supply terminal 27 generates heat by itself. Therefore, generation of a cooling spot on the upper surface of the ceramic substrate 21, that is, the heating surface can be suppressed. Further, since W / d is 1.1 to 10, not only the generation of cooling spots can be sufficiently suppressed, but also the generation of hot spots due to heat generation of the power supply terminals 27 can be suppressed. 4 can also be seen as a projection image when the power feeding terminal 27 and the resistance heating element 23 are virtually projected onto the heating surface of the ceramic substrate 21, according to which the projection image of the power feeding terminal 27 is the resistance heating element. 23, the generation of cooling spots can be more effectively suppressed. Further, since the power feeding terminal 27 is fixed to the ceramic substrate 21 by mechanical joining using screws and chemical joining using brazing material, there is no risk of dropping off even in an atmosphere of corrosive gas.

  Further, the inside of the ceramic sleeve 41 and the inside of the reaction chamber 12 are completely separated from each other, and even if the inside of the reaction chamber 12 becomes an atmosphere of corrosive gas (for example, a reaction gas in a plasma state), the ceramic sleeve. Since each member accommodated in 41 does not touch corrosive gas, it does not corrode. Here, in the above-described embodiment, the both end portions 23a and 23a of the resistance heating element 23 are disposed at substantially the center of the ceramic substrate 21, but may be disposed at any position. However, when both end portions 23a and 23a are arranged at positions deviating from the position facing the opening of the ceramic sleeve 41, wiring is performed from the position to the position facing the opening of the ceramic sleeve 41 inside the ceramic substrate 21. It is preferable to join the power supply terminal 27 and the resistance heating element 23 after forming the electrode. By doing so, the power supply terminal 27 is disposed inside the ceramic sleeve 41 and therefore does not come into contact with corrosive gas.

  Furthermore, since the ceramic sleeve 41 also serves to firmly support the ceramic substrate 21, it can be prevented that warpage occurs when the ceramic substrate 21 is heated to a high temperature. If warpage occurs in the ceramic substrate 21, the object to be processed 18 is damaged or the entire surface of the object to be processed 18 cannot be heated uniformly. However, in this embodiment, the ceramic sleeve 41 prevents warpage. Such a problem does not occur. Further, in addition to the lower electrode 33 for generating plasma, an electrostatic electrode may be embedded in the ceramic substrate 21 of the present embodiment. In this way, the ceramic substrate 21 functions as an electrostatic chuck provided with heating means. . At this time, you may comprise so that the lower electrode 33 may serve as an electrostatic electrode.

1. Each member of the present embodiment may be configured as follows.
(1) About the ceramic substrate 21 of this embodiment Although it does not specifically limit as a ceramic material which comprises the ceramic substrate 21, For example, a nitride ceramic, a carbide ceramic, an oxide ceramic etc. are mentioned. Examples of the nitride ceramic include aluminum nitride, silicon nitride, boron nitride, and titanium nitride. Examples of the carbide ceramic include silicon carbide, zirconium carbide, boron carbide, titanium carbide, tantalum carbide, and tungsten carbide. Examples of the oxide ceramic include alumina, silica, cordierite, mullite, zirconia, and beryllia. These ceramic materials may be used independently and may use 2 or more types together. Among these, nitride ceramics and carbide ceramics are preferable. Nitride ceramics and carbide ceramics have a coefficient of thermal expansion smaller than that of metal and mechanical strength is significantly higher than that of metal. Therefore, even if the thickness of the ceramic substrate 21 is reduced, it is not warped or distorted by heating. This is because the ceramic substrate 21 can be thin and light. Further, since the thermal conductivity is high, the followability when the temperature of the resistance heating element 23 is changed by controlling the voltage or current is good. More preferably, it is a nitride ceramic. This is because nitride ceramics are excellent in heat resistance and mechanical properties and have high thermal conductivity. More preferred is aluminum nitride. This is because the coefficient of thermal expansion is as high as 180 W / m · K, and the temperature followability of the ceramic substrate is the best.

The ceramic substrate 21 may contain a sintering aid. Examples of the sintering aid include alkali metal oxides, alkaline earth metal oxides, rare earth oxides, and the like. Among _{these, CaO, Y 2 O 3,} Na 2 O, Li 2 O, Rb 2 O is preferable. When silicon carbide is used as the ceramic material, B ₄ C, C, and AlN are preferable. The preferable lower limit of the content of the sintering aid is 0.1% by weight, and the preferable upper limit is 20% by weight. The ceramic substrate 21 may contain alumina.

  The porosity of the ceramic substrate 21 is preferably 5% or less (including 0%). This is because it is possible to suppress a decrease in thermal conductivity and warpage at a high temperature. The porosity can be measured by, for example, the Archimedes method. The shape of the ceramic substrate 21 is not particularly limited, but is preferably a disc shape, and the diameter is preferably 200 mm or more, and more preferably 250 mm or more. This is because the ceramic substrate 21 having such a large diameter can mount a large-diameter silicon wafer when the plasma generator is used for semiconductor manufacturing. On the other hand, when the diameter exceeds 400 mm, the Young's modulus decreases at a high temperature, and deformation easily occurs due to its own weight. When deformed, the distance between the ceramic substrate 21 and the object to be heated (for example, a wafer) becomes large and it becomes difficult for both to be in close contact with each other. For this reason, it is preferable that a diameter is 400 mm or less. A preferable lower limit of the thickness of the ceramic substrate 21 is 5 mm, and a preferable upper limit is 20 mm. If it is less than 5 mm, the strength itself of the ceramic substrate 21 is lowered and easily broken, and if it exceeds 20 mm, the temperature followability tends to be lowered. A more preferable lower limit is 12 mm, and a more preferable upper limit is 16 mm. If the thickness is less than 12 mm, the strength of the ceramic substrate 21 tends to be slightly reduced, and if it exceeds 16 mm, the temperature followability tends to be somewhat resistant.

  The heating surface of the ceramic substrate 21 preferably has a surface roughness Ra based on JIS B 0601 of 1.0 μm or less. This is because if Ra exceeds 1.0 μm, the temperature distribution of the heated object (for example, a wafer) on the heating surface tends to vary, and the surface of the heated object may not be uniformly processed. . The thickness of the ceramic substrate 21 is preferably in the range of 5 mm to 20 mm. If the thickness is less than 5 mm, the strength of the ceramic substrate may not be sufficiently obtained, and if it exceeds 20 mm, the temperature responsiveness of the ceramic substrate may be reduced and the temperature may be difficult to control. The convex portion 21 a provided on the heating surface of the ceramic substrate 21 is for heating the object to be heated such as a wafer away from the ceramic substrate 21. Thereby, it is possible to prevent impurities such as a sintering aid for the ceramic substrate 21 from diffusing into the object to be heated. In addition, since the surface temperature of the ceramic substrate 21 is not completely uniform, the temperature of the heated body may become non-uniform if it is brought into direct contact. Therefore, the heated body is separated and thermally diffused to separate the heated body. Can be heated uniformly.

(2) About the resistance heating element 23 of this embodiment In order to form the resistance heating element 23, it is preferable to use a conductor green sheet or a conductor paste. As an example of forming the resistance heating element 23 using a conductor green sheet, the conductor green sheet is formed by punching into a heater pattern, and then sandwiched between the ceramic green sheets and fired to form a ceramic substrate. For example, a resistance heating element 23 may be embedded inside. At this time, the conductor green sheet preferably contains conductive ceramic particles and / or metal particles, and further contains a resin, a solvent, a thickener and the like. On the other hand, as an example of forming the resistance heating element 23 using a conductor paste, after forming a pattern using a conductor paste on a ceramic green sheet using a screen printing method, another ceramic green sheet is laminated, The resistance heating element 23 can be embedded in the ceramic substrate 21 by firing. At this time, the conductor paste preferably uses a resin, a solvent, a thickener and the like in addition to the conductive ceramic particles and / or metal particles in order to use a screen printing method. Here, the conductive ceramic particles and the metal particles are contained in order to ensure conductivity. Examples of the conductive ceramic particles include particles made of carbide of tungsten or molybdenum. These conductive ceramic particles may be used alone or in combination of two or more. Examples of the metal particles include particles made of noble metals such as gold, silver, platinum, and palladium; lead, tungsten, molybdenum, nickel, and the like. This is because these metals are relatively difficult to oxidize and have sufficient resistance to generate heat. These metal particles may be used independently and may use 2 or more types together. The preferable lower limit of the particle size of the conductive ceramic particles or metal particles is 0.1 μm, and the preferable upper limit is 10 μm. If it is less than 0.1 μm, it tends to be oxidized, and if it exceeds 10 μm, it is difficult to sinter and the resistance value tends to increase. Although it does not specifically limit as a shape of electroconductive ceramic particle or metal particle, For example, spherical shape, scale shape, etc. are mentioned. It may be a mixture of the spheres and the flakes. When the metal particles are flakes or a mixture of spheres and flakes, the metal oxides between the metal particles are easily retained, and the resistance heating element 23 and the ceramic substrate 21 are in close contact with each other. This is advantageous because the resistance can be increased and the resistance can be increased. Although it does not specifically limit as resin, For example, an epoxy resin, a phenol resin, etc. are mentioned. Moreover, it does not specifically limit as a solvent, For example, isopropyl alcohol etc. are mentioned. Moreover, it does not specifically limit as a thickener used for a conductor paste, For example, a cellulose etc. are mentioned.

  The cross section of the resistance heating element 23 may be any of a square shape, an elliptical shape, a spindle shape, and a bowl shape, but is preferably flat. This is because the flatter surface tends to radiate heat toward the heating surface, so that the amount of heat propagation to the heating surface can be increased, and the temperature distribution on the heating surface tends to be uniform. The overall shape of the resistance heating element 23 may be a spiral shape. The preferable lower limit of the thickness of the resistance heating element 23 is 1 μm and the preferable upper limit is 50 μm. The preferable lower limit of the width of the resistance heating element 23 is 1 mm and the preferable upper limit is 30 mm. The resistance heating element 23 can change its resistance value by changing its thickness and width, but this range is the most practical. Note that the resistance value of the resistance heating element 23 increases as the cross-sectional area decreases. The formation position of the resistance heating element 23 inside the ceramic substrate 21 is not particularly limited, but it is preferable that at least one layer is formed at a position from the bottom surface of the ceramic substrate 21 to 60% of the substrate thickness. This is because the heat is diffused while propagating to the heating surface, and the temperature on the heating surface tends to be uniform.

  The resistance heating element 23 may have a pad portion formed at the end 23a. The pad portion is formed in a thin disk shape that is the same as or smaller than the width of the resistance heating element 23, and increases the contact area between the conductor filling layer 26 and the resistance heating element 23 to ensure the conduction between the two. Fulfill. The material constituting the pad portion is not particularly limited as long as it is a conductive material, and examples thereof include the same material as the resistance heating element 23, the same material as the conductor filling layer 26, and the like. It may be a mixture of materials (alloy) or the like.

(3) Regarding the power supply terminal 27 of the present embodiment The material of the power supply terminal 27 is not particularly limited. The melting point metal is optimal compared to other metals. The size of the power supply terminal 27 is not particularly limited because it is appropriately adjusted depending on the size of the ceramic substrate 21 and the resistance heating element 23 to be used, but the preferable lower limit of the diameter of the shaft portion of the power supply terminal 27 is 0.5 mm. The preferable upper limit is 20 mm, the preferable lower limit of the length of the shaft portion is 1 mm, and the preferable upper limit is 30 mm.

(4) About the lower electrode 33 of this embodiment In order to form the lower electrode 33, it is preferable to use a conductor green sheet or a conductor paste. Since these have already been described in the method of forming the resistance heating element 23, description thereof is omitted here. As for the thickness of the lower electrode 33, a preferable lower limit is 5 μm and a preferable upper limit is 300 μm. If the thickness is less than 5 μm, the degree of thickness variation is greatly reflected, so that the resistance value variation is large, and the thickness variation of the vapor phase growth surface formed on the workpiece 18 is large. If it exceeds 300 μm, the resistance value may be too low. In the embodiment described above, the lower electrode 33 has two layers, but it may be one layer or three or more layers. Note that, when the lower electrode 33 and the conductive member 35 are joined, the high frequency application terminal 37 having the same structure as the power supply terminal 27 is used. However, the high frequency application terminal 37 may not be used and may be joined by another method.

(5) About the temperature measuring element 45 of this embodiment As the temperature measuring element 45, a thermocouple, a platinum resistance temperature detector, a thermistor etc. are mentioned, for example. Among these, examples of the thermocouple include K-type, R-type, B-type, S-type, E-type, J-type, and T-type thermocouples as described in JIS C 1602 (1980). Among them, a K-type thermocouple is preferable. As the thermocouple, a sheathed thermocouple in which a thermocouple is housed in a sheath such as stainless steel or an insulating tube can be used. The sheath thermocouple can be used by being pressed against the bottom of the bottomed hole 46 by an elastic body such as a spring. The thermocouple may be bonded to the bottom of the bottomed hole 46 using gold brazing, silver brazing or the like, and after being inserted into the bottomed hole 46, sealed with a heat resistant resin, ceramic (silica gel or the like), etc. You may use both together. The gold solder is at least selected from 37-80.5 wt% Au-63-19.5 wt% Cu alloy, 81.5-82.5 wt% Au-18.5-17.5 wt% Ni alloy. One is preferred. This is because the melting temperature is 900 ° C. or higher and it is difficult to melt even in a high temperature region. As the silver solder, for example, an Ag-Cu-based solder can be used. Examples of the heat resistant resin include a thermosetting resin, particularly an epoxy resin, a polyimide resin, a bismaleimide-triazine resin, and the like. These resins may be used alone or in combination of two or more. Further, instead of or in addition to the temperature measuring element 45, an optical temperature measuring means such as a thermoviewer can be used. When a thermoviewer is used, the temperature of the heated surface of the ceramic substrate 21 can be measured, and the surface temperature of the object 18 such as a silicon wafer can be directly measured. The accuracy of control is improved.

  The bottomed hole 46 in which the temperature measuring element 45 is disposed is drilled from the lower surface of the ceramic substrate 21 toward the heating surface, and the bottom of the bottomed hole 46 is relatively heated from the resistance heating element 23. It is preferable to form near. The distance between the bottom of the bottomed hole 46 and the heating surface is preferably 0.1 mm to ½ of the thickness of the ceramic substrate 21. If the thickness is less than 0.1 mm, heat may be radiated from the bottomed hole 46 and the temperature distribution on the heating surface may become non-uniform. This is because it becomes easy to be affected and accurate temperature control cannot be performed. By setting the distance between the bottom of the bottomed hole 46 and the heating surface to be 0.1 mm to ½ of the thickness of the ceramic substrate, the temperature measuring place is closer to the heating surface than the resistance heating element 23 and more accurate. The temperature of the object 18 can be measured. The preferable lower limit of the diameter of the bottomed hole 46 is 0.3 mm, and the preferable upper limit is 5 mm. If the thickness is less than 0.3 mm, the workability deteriorates and the distance from the heating surface cannot be made uniform. If the thickness exceeds 5 mm, the heat dissipation becomes too large, and the temperature distribution on the heating surface becomes uneven. Because there is a tendency to become. A plurality of such bottomed holes 46 are preferably arranged so as to be symmetrical with respect to the center of the ceramic substrate 21 and to form a cross. This is because the temperature measuring element can be inserted into each bottomed hole, the temperature can be measured at several places on the heating surface, and the average can be set as the temperature of the entire heating surface, thereby improving the temperature measurement accuracy.

(6) Ceramic sleeve 41 of the present embodiment The ceramic material constituting the ceramic sleeve 41 is not particularly limited. For example, nitride ceramics such as aluminum nitride, silicon nitride, boron nitride, and titanium nitride; silicon carbide, carbonized Examples thereof include carbide ceramics such as zirconium, titanium carbide, tantalum carbide, and tungsten carbide; oxide ceramics such as alumina, zirconia, cordierite, and mullite. Of these, aluminum nitride is most preferred. This is because the thermal conductivity is the highest, 180 W / m · K, and the temperature followability is excellent. The ceramic material constituting the ceramic sleeve 41 is preferably the same as the ceramic material constituting the ceramic substrate 21. This is because the ceramic substrate 21 and the ceramic sleeve 41 can be bonded by diffusion bonding. However, the ceramic sleeve 41 may not contain a sintering aid. Since the sintering aid is contained in the ceramic substrate 21, the sintering aid contained in the ceramic substrate 21 diffuses into the ceramic sleeve 41 when heated when the ceramic substrate 21 and the ceramic sleeve 41 are joined. As a result, ceramic crystal grain growth occurs at the boundary, and as a result, both are bonded and integrated (diffusion bonding). The ceramic sleeve 41 is hollow and substantially cylindrical, but the cross-sectional shape when cut perpendicularly to the wall surface of the cylinder is not particularly limited, and examples thereof include a circular shape, an elliptical shape, and a polygonal shape. . In general, since the ceramic substrate 21 has a disk shape, the cross-sectional shape of the ceramic sleeve 41 is preferably circular.

(7) Definition of measurement method The thickness is measured by cutting the ceramic substrate 21 in a direction perpendicular to the heating surface, and measuring objects (lower electrodes) for each of the two ceramic substrates 21 observed at that time. 33 and the distance between the upper boundary and the lower boundary of the resistance heating element 23) were measured at arbitrary 10 points, and the average value was defined as the thickness of the lower electrode 33. The particle size was defined as the major diameter of the conductive ceramic particles observed in the cross section of the resistance heating element 23 observed when the ceramic substrate 21 was cut in a direction perpendicular to the heating surface.

  2. A procedure for manufacturing the susceptor 20 of this embodiment will be described below. 5A to 5C and FIG. 6 are cross-sectional views schematically showing an example of a manufacturing procedure of the susceptor 20.

(1) Ceramic green sheet manufacturing process (see FIG. 5A)
First, a ceramic powder is mixed with a binder, a solvent, and the like to prepare a paste, which is formed into a sheet shape by a doctor blade method to produce a ceramic green sheet 110. As the ceramic powder, aluminum nitride or the like can be used, and if necessary, a sintering aid such as yttria, a compound containing Na, Ca, or the like may be added. The binder is preferably at least one selected from the group consisting of an acrylic binder, ethyl cellulose, butyl cellosolve and polyvinyl alcohol. As the solvent, α-terpineol and / or glycol are preferable. The preferable lower limit of the thickness of the green sheet 110 is 0.1 mm, and the preferable upper limit is 5 mm. Further, when the ceramic substrate 21 is manufactured, the hole 126 for forming the conductor filling layer 26 provided immediately below the end 23 a of the resistance heating element 23 and the conductor filling layer 36 provided immediately below the lower electrode 33 are formed. Hole 136 for forming (filled with conductor paste), hole 146 for forming bottomed hole 46 (filled with conductor paste), hole 150 for forming lifter pin insertion hole 50, and heating surface A concave portion 121 or the like for forming the convex portion 21a is necessary, and such holes and concave portions are formed in some of the ceramic green sheets 110 that are stacked in accordance with them. Such holes and recesses may be formed after producing a green sheet laminate described later, or may be formed after producing and firing the green sheet laminate.

  In addition to the method of providing the concave portion 121 on the surface of the ceramic heater and fitting the spherical body or the like to provide the convex portion 21a, the mask is placed on the surface of the ceramic heater and sandblasted to form a plurality of convex portions. A method may be adopted.

(2) WC paste printing process (see FIG. 5A)
A tungsten paste (WC) paste is printed on a predetermined number of ceramic green sheets 110 to be laminated to form a conductive paste layer 133 to be a lower electrode 33 for generating plasma, and the holes 136 are filled with the conductive paste. Thus, the conductive paste filling layer 236 is formed. A ceramic green sheet 110 in which a plurality of WC heater pattern sheets 123 formed by punching a WC green sheet into a pattern of the resistance heating element 23 is formed by forming a WC paste into a sheet shape by a doctor blade method to form a WC green sheet. Sandwiched at a predetermined position. At this time, the WC heater pattern sheet 123 is arranged so that both ends thereof overlap the holes 126 and 126. Also, the hole 126 is filled with a conductive paste to form a conductive paste filling layer 226. The conductive paste contains metal particles or conductive ceramic particles. Examples of such a conductive paste include 85 to 87 parts by weight of metal particles or conductive ceramic particles; 1.5 to 10 weights of at least one binder selected from the group consisting of acrylic, ethyl cellulose, butyl cellosolve, and polyvinyl alcohol. Part; a composition (paste) mixed with 1.5 to 10 parts by weight of a solvent composed of α-terpineol and / or glycol. The conductive paste used for the conductive paste layer 133, the WC heater pattern sheet 123, and the conductive paste filling layers 236 and 226 may have the same composition or different compositions.

(3) Ceramic green sheet lamination process (see FIG. 5B)
In order to produce the ceramic substrate 21, a plurality of ceramic green sheets 110 are laminated to form a green sheet laminate 210. At this time, from the upper layer to the lower layer, the ceramic green sheet 110 in which the hole 150 serving as the lifter pin insertion hole 50 and the recess 121 are formed, the ceramic green sheet 110 in which only the hole 150 is formed, and the conductor serving as the lower electrode 33 in the upper layer. In addition to the ceramic green sheet 110 on which the paste layer 133 and the conductor paste filling layer 236 immediately below it are formed, the conductor paste layer 133 to be the lower electrode 33 below, the conductor paste filling layer 236 and the like below are formed. In addition to the ceramic green sheet 110 and the hole 150, in addition to the ceramic green sheet 110 and the WC heater pattern sheet 123 and the hole 150 obtained by punching the ceramic green sheet 110 and the WC green sheet in which the hole 146 serving as the bottomed hole 46 is formed. Conductive paste filling layer 236 and Ceramic green sheets 110 hole 146 and conductive paste filling layer 226 serving as a bottom hole 46 is formed, are laminated in the order of the ceramic green sheet 110 with a hole 150 and hole 146 are formed. Since FIG. 5 is a schematic diagram, the actual number of stacked layers is different from the number shown in FIG. At this time, the number of the green sheets 110 laminated on the upper side of the green sheet 110 on which the WC heater pattern sheet 123 is formed is larger than the number of the green sheets 110 laminated on the lower side, so that the resistance heating elements 23 of the ceramic substrate 21 are formed. The position in the vertical direction (thickness direction) is biased toward the bottom surface. Specifically, the number of the upper green sheets 110 is preferably 20 to 50, and the number of the lower green sheets 110 is preferably 5 to 40.

(4) Green sheet laminate firing step (see FIGS. 5C and 5D)
Next, the green sheet laminate 210 is heated and pressurized to sinter the ceramic green sheet 110 and the internal conductor paste filling layers 226, 236, etc., so that the resistance heating element 23, the lower electrode 33, and the conductor filling layer are sintered. A ceramic substrate 21 having 26, 36, etc. embedded therein is obtained. The preferable lower limit of the heating temperature is 1000 ° C., and the preferable upper limit is 2100 ° C. Heating is performed in an inert gas atmosphere or in a vacuum. As the inert gas, for example, argon, nitrogen or the like can be used. The preferable lower limit of the pressure of pressurization is 10 MPa, and the preferable upper limit is 20 MPa. In the case where the hole 150 serving as the lifter pin insertion hole 50 and the hole 146 serving as the bottomed hole 46 for inserting the temperature measuring element 45 are not previously formed in the ceramic green sheet 110, the ceramic substrate 21 after firing is formed. After the surface polishing or the like is performed, the lifter pin insertion hole 50 or the bottomed hole 46 is formed by performing a blasting process such as drilling or sandblasting. Next, screw holes 22 are formed by drilling or blasting at the positions where the conductor filling layers 26 and 36 are formed on the bottom surface of the ceramic substrate 21.

(5) Ceramic sleeve manufacturing process Ceramic powder, such as aluminum nitride powder, is put into a substantially cylindrical mold, and after being cut as necessary, it is heated at 1000 to 2100 ° C. and normal pressure. The substantially cylindrical ceramic sleeve 41 is manufactured by sintering. At this time, the ceramic sleeve 41 is preferably substantially cylindrical. Sintering is performed in an inert gas atmosphere or in a vacuum. As the inert gas, for example, argon, nitrogen or the like can be used. Next, the end surface of the ceramic sleeve 41 is polished and flattened.

(6) Ceramic sleeve joining process (see Fig. 6)
In a state where the vicinity of the center of the bottom surface of the ceramic substrate 21 and the periphery of the upper opening of the ceramic sleeve 41 are in contact with each other, the ceramic substrate 21 and the ceramic sleeve 41 are heated to join them. At this time, the screw holes 22 connected to the conductor filling layers 26 and 36 of the ceramic substrate 21 are accommodated inside the ceramic sleeve 41. The method for joining the ceramic substrate 21 and the ceramic sleeve 41 is not particularly limited, but the concentration of the sintering aid contained in the ceramic substrate 21 and the concentration of the sintering aid contained in the ceramic sleeve 41 are adjusted to be different. In addition, a method in which both are brought into contact at a joining position and then joined by heating is preferable. In this case, the sintering aid moves from a member having a high concentration of the sintering aid to a member having a low concentration, and particles grow across the interface to form a firm joint surface. Bond strength is obtained. As another method for joining the ceramic substrate 21 and the ceramic sleeve 41, for example, a solution containing a sintering aid in the ceramic material constituting the ceramic substrate 21 and the ceramic sleeve 41 is used on the joining surface of the ceramic substrate 21 and the ceramic sleeve 41. A method of applying and sintering this (diffusion bonding); A method of applying a ceramic paste having the same main component as the ceramic constituting the ceramic substrate 21 and the ceramic sleeve 41 and sintering it; oxidation The method of joining using adhesives, such as physical glass, is mentioned.

(7) Feeding terminal mounting process (see Fig. 6)
The screw holes 22 connected to the conductor filling layers 26 and 36 are screwed with a power supply terminal 27 and a high frequency application terminal 37 which are tungsten screw pins to which a brazing material is applied, and then a conductive material which is a nickel rod with a brazing material. The members 29 and 35 are screwed into the terminals 27 and 37 and then heated to perform brazing. At this time, 900-1100 degreeC is suitable for heating temperature. Further, the temperature measuring element 45 is inserted into the bottomed hole 46 formed in the bottom surface of the ceramic substrate 21, and the manufacture of the susceptor 20 is finished.

  Below, the specific example of the manufacturing method of the susceptor 20 is demonstrated. Here, the susceptor 20 having the same configuration as that of the above-described embodiment was manufactured except that the end 23a of the resistance heating element 23 was disposed at a position off the center of the ceramic substrate 21.

(1) Aluminum nitride powder (manufactured by Tokuyama Corporation, average particle size 1.1 μm) 100 parts by weight, yttrium oxide (Y ₂ O ₃ : yttria, average particle size 0.4 μm) 4 parts by weight, acrylic binder 11.5 parts by weight Using a paste obtained by mixing 0.5 parts by weight of a dispersant and 53 parts by weight of an alcohol composed of 1-butanol and ethanol, molding was performed by a doctor blade method to produce a ceramic green sheet having a thickness of 0.47 mm.

  (2) Next, this ceramic green sheet was dried at 80 ° C. for 5 hours, and then a hole was formed by punching in a portion to be a conductor filling layer.

  (3) 10000 parts by weight of tungsten carbide (WC-10) particles having an average particle diameter of 1 μm, 1509 parts by weight of an acrylic binder (SA-545 manufactured by Mitsui Chemicals), and 175 parts by weight of a plasticizer (DOA manufactured by Kuroki Kasei) Then, 560 parts by weight of 1-butanol and 432 parts by weight of ethanol were mixed, and a WC green sheet (WC: tungsten carbide) having a thickness of 65 μm ± 5 μm was produced by a doctor blade method. This was dried in air at 25 ° C. for 48 hours to form a WC green sheet having a thickness of 55 μm ± 5 μm, and this WC green sheet was punched to form a WC heater pattern sheet for a resistance heating element.

  (4) A conductor paste is prepared by mixing 100 parts by weight of tungsten carbide particles having an average particle diameter of 3 μm, 1.9 parts by weight of an acrylic binder, 3.7 parts by weight of α-terpineol solvent, and 0.2 parts by weight of a dispersant. did.

  (5) A conductor paste layer to be a lower electrode for plasma generation is formed on the ceramic green sheet after the treatment of (2) by screen printing in a mesh shape using the conductor paste of (4). In addition, a conductor paste filling layer was formed by filling a hole formed in a portion to be a conductor filling layer immediately below the lower electrode with a conductor paste. On the other hand, for the green sheet in which holes are formed in the portion of the ceramic green sheet that has been subjected to the treatment (1) to be the conductor filling layer immediately below the resistance heating element, the conductor paste filling layer is filled with the conductor paste. It was. Thereafter, these were dried in air at 25 ° C. for 8 hours or more.

  (6) The various ceramic green sheets obtained in (5) above and the WC heater pattern sheet obtained in (3) above (the outline of the heater pattern is shown in FIG. 9) are laminated, and the pressure is 130 ° C. and 8 MPa. To form a green sheet laminate. Here, two ceramic green sheets on which a conductive paste layer serving as a lower electrode was formed were used.

  (7) Next, the green sheet laminate was degreased in nitrogen gas at 600 ° C. for 5 hours, and hot pressed at 1840 ° C. and a pressure of 15 MPa for 6 hours to obtain a ceramic plate having a thickness of 15 mm. This is cut into a 330 mm disk shape, and has a resistance heating element with a thickness of 6 μm and a width of 10 mm inside, a conductor filling layer connected to the resistance heating element, a lower electrode for plasma generation, and a conductor filling layer connected to the lower electrode A ceramic substrate having

  (8) Then, a bottomed hole for inserting a temperature measuring element by drilling and a screw hole for screwing a power supply terminal were formed in the obtained ceramic substrate. The heating surface of the ceramic substrate was blasted to Ra = 0.8 μm.

  (9) Aluminum nitride powder (manufactured by Tokuyama Co., Ltd., average particle size 0.6 μm) is molded into a cylindrical shape by a dry rubber press method and degreased under an oxidizing atmosphere at 600 ° C. for 5 hours. A ceramic sleeve made of aluminum nitride (outer diameter 220 mm, inner diameter 210 mm, length 190 mm) fired under the conditions of 1860 ° C. for 6 hours is applied to the ceramic substrate after the step (8) in nitrogen gas at 1850 ° C. And heated to form a susceptor.

  (10) Drilling a ceramic substrate to insert through holes for silicon wafer lifter pins, and wafer support pins for separating the wafer from the surface of the ceramic substrate by about 100 μm A recess having a diameter of 3 mm for fitting the above was processed by sandblasting.

  (11) A tungsten power supply terminal (W / d = 2) having a diameter of 5 mm and a length of 12 mm, to which an Au—Ni brazing material is adhered, is screwed into a screw hole connected to the conductor filling layer immediately below the resistance heating element. A rod-shaped conductive member made of nickel and having an Au—Ni brazing material attached to the tip thereof was screwed into the screw hole provided in, and brazed with each brazing material in a nitrogen atmosphere at 1030 ° C. for 28 minutes. At the same time, the high-frequency terminal was screwed into the screw hole, the conductive member was screwed into the screw hole provided in the high-frequency terminal, and these were also brazed. The resistance heating element was disposed at a position 5 mm from the heating surface.

  (12) The periphery of the lower opening of the ceramic sleeve of the susceptor was fixed to the bottom surface of the reaction chamber via an O-ring, and a sheath thermocouple as a temperature measuring element was pressed against the bottom of the bottomed hole with a spring and fixed.

  Example 1 is the same as Example 1 except that the diameter of the power supply terminal is 8.8 mm and the length is 15 mm (W / d = 1.1).

  Example 1 is the same as Example 1 except that titanium nitride particles having an average particle diameter of 3 μm were used as the conductive ceramic particles when preparing the conductive paste for the lower electrode for plasma generation, and the diameter of the power supply terminal was 1 mm and the length was 10 mm. The same is true (W / d = 10).

Comparative Example 1

  The same as Example 1 except that the diameter of the power supply terminal was 0.7 mm and the length was 10 mm (W / d = 14).

Comparative Example 2

  Example 1 is the same as Example 1 except that the diameter of the power supply terminal is 10 mm and the length is 10 mm (W / d = 1).

Comparative Example 3

  The same as Example 1 except that the diameter of the power supply terminal was 20 mm and the length was 15 mm (W / d = 0.5).

Comparative Example 4

Here, a tungsten wire having a diameter of 0.1 mm was coiled (coil diameter 2 mm), and this was bonded to a tungsten pin (diameter 3 mm, length 10 mm) with an Au brazing material. The tungsten pin and the tungsten coil were fitted into an aluminum nitride molded body in which grooves and holes were formed by drilling, and aluminum nitride powder was added from above, and hot pressed at 1890 ° C. and 200 kg / cm ² to sinter. Further, the surface of the aluminum nitride molded body was polished to expose the tungsten pin, and a screw was formed on the tungsten pin by grinder processing.

Test example

  The ceramic substrate of the susceptor obtained in Examples 1 to 3 and Comparative Examples 1 to 3 was heated at a set temperature of 500 ° C. at a heating rate of 15 ° C./min, 10 minutes after reaching 500 ° C. and becoming a steady state. The heated surface was observed with a thermoviewer (JEOL Thermoviewer JTG6300 (Stirling cooler cooling type)). The result is shown in FIG. 7A is an observation image of the thermoviewer of Comparative Example 2, and FIG. 7B is an observation image of the thermoviewer of Example 1. FIG. Here, points B and C represent markers. That is, since magnification is different between FIG. 7A and FIG. 7B, points B and C representing the same coordinate position are shown as markers. Also, in the figure, the black circle part located slightly above the center of points B and C is the lifter insertion hole (no lifter pin), and the other black part is a recess formed on the heating surface (with a spherical body inserted here) For forming convex portions for supporting the wafer). Comparing FIG. 7A and FIG. 7B, in Comparative Example 2, there is a darkened portion near the point B, and there is also a darkened portion in the lower left (enclosed by an ellipse in the figure). . These two portions hit the attachment position of the power supply terminal and are darkened (in fact, are fading), it can be seen that a cooling spot is generated. On the other hand, in Example 1, a cooling spot is generated because it is not dark and is uniform gray (actually light blue) even near the point B where the power supply terminal is attached and around the lower left thereof. You can see that it is not. In addition, when the ceramic substrate of the susceptor obtained in Comparative Example 4 was also heated to 500 ° C. at 15 ° C./min and the heating surface was observed with the aforementioned thermoviewer, a cooling spot was observed at the position shown in FIG. It was.

  Further, the ceramic substrates of the susceptors obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were heated at a set temperature of 500 ° C. and a heating rate of 15 ° C./min, and after reaching 500 ° C. and becoming a steady state, 10 minutes. Later, the temperature To of the heating surface immediately above the power supply terminal and the temperature Ts of the heating surface at a position 18 mm in the center direction of the ceramic substrate from the power supply terminal were measured, and the difference ΔT (= To−Ts) was calculated. FIG. 8 is a graph when the horizontal axis is W / d and the vertical axis is ΔT. When W / d is zero, it indicates that the temperature distribution on the heating surface is substantially uniform, and that the variation in temperature distribution increases with distance from zero. Further, when W / d is negative, a cooling spot is generated at the mounting position of the power supply terminal, and when W / d is positive, it indicates that a hot spot is generated at the mounting position of the power supply terminal. As can be seen from this graph, ΔT is zero when W / d is in the range of 1.1 to 10, and the temperature distribution on the heating surface is substantially uniform, whereas when W / d is less than 1.1, A cooling spot is generated, and when W / d exceeds 10, a hot spot is generated.

1 is a schematic explanatory diagram of a plasma CVD apparatus 10. 2 is a partial cross-sectional view of a susceptor 20. FIG. FIG. 3 is an enlarged view of a main part of FIG. 2. It is AA sectional drawing of FIG. FIG. 6 is a cross-sectional view showing an example of a manufacturing procedure (first half) of the susceptor 20. FIG. 6 is a cross-sectional view showing an example of a manufacturing procedure (second half) of the susceptor 20. It is an observation image of a thermoviewer. It is a graph showing the relationship between W / d and the uniformity of a temperature distribution. It is a schematic explanatory drawing of a heater pattern. It is explanatory drawing of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Plasma CVD apparatus, 12 Reaction chamber, 14 Exhaust port, 16 Control valve, 18 Processed object, 20 Susceptor, 21 Ceramic substrate, 21a Convex part, 22 Screw hole, 23 Resistance heating element, 23a End part, 26 Conductor filling layer 27 Power supply terminal, 27a Screw thread, 27b Screw hole, 28 Brazing material, 29 Conductive member, 29b Male screw, 33 Lower electrode, 35 Conductive member, 36 Conductor filling layer, 37 High frequency application terminal, 41 Ceramic sleeve, 42 Flange, 43 O-ring, 45 Temperature measuring element, 46 Bottomed hole, 50 Lifter pin insertion hole, 51 Lifter pin, 60 Shower head, 61 Valve, 63 Upper electrode, 65 High frequency, 67 Power supply, 110 Ceramic green sheet, 121 Recess, 123 WC heater Pattern sheet, 126 holes, 133 conductor pace Layers, 136 holes, 146 holes, 150 holes, 210 green sheet laminate, 226 conductive paste filling layer, 236 conductive paste filling layer, the width of the W resistance heating element, the diameter of the d power supply terminals.

Claims (9)

A ceramic substrate with an embedded resistance heating element;
A power feeding terminal formed so that one end is connected to the resistance heating element and the other end is exposed to the outside from the surface opposite to the heating surface of the ceramic substrate;
With
A ceramic heater in which a diameter of the power supply terminal is smaller than a width of the resistance heating element.   The ceramic heater according to claim 1, wherein the power supply terminal generates heat when energized.   The ceramic heater according to claim 1 or 2, wherein W / d is 1.1 to 10, where W is a width of the resistance heating element and d is a diameter of the power supply terminal.   The ceramic heater according to any one of claims 1 to 3, wherein the resistance heating element has a width of 1 to 30 mm and a diameter of the power supply terminal of 0.5 to 20 mm.   The ceramic heater according to claim 1, wherein a projection image when the power feeding terminal is virtually projected onto the heating surface is included in a projection image when the resistance heating element is virtually projected onto the heating surface.   6. The ceramic heater according to claim 1, wherein at least one layer of the resistance heating element is formed at a position from a surface opposite to a heating surface of the ceramic substrate to 60% of a thickness of the substrate.   The ceramic heater according to claim 1, wherein a main component of the resistance heating element is a carbide ceramic, a main component of the ceramic substrate is a nitride ceramic, and a main component of the power supply terminal is a refractory metal. .   The power supply terminal has a thread on the outer periphery, is screwed into a screw hole formed on a surface opposite to the heating surface of the ceramic substrate and mechanically joined, and one end is brazed to the resistance heating element. The ceramic heater according to any one of claims 1 to 7, which is chemically bonded to each other.   The ceramic heater according to any one of claims 1 to 8, which is installed in a plasma generator.