JP2018182280A - Ceramic member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic member capable of easily heating to a wafer at a predetermined temperature while suppressing the generation of a leak current.SOLUTION: A ceramic heater 100 includes a mounting surface 11 on which a wafer is mounted, and is made by combining a RF plate 10 formed by a ceramic sinter body in which a RF electrode 30 is embedded, and a heater plate 20 formed by the ceramic sinter body in which a heater 40 is embedded through a space S on the side opposite to the mounting surface of the RF plate 10. A relation of the minimum height H(mm) of the space in a direction vertical to the mounting surface 11, a ratio A of a total area of a part where the RF plate 10 to a flat surface area along the mounting surface 11 to be regulated by an outer edge of the mounting surface 11 and the heater plate 20 are combined, and a distance D (mm) between the RF electrode 30 and the heater 40 satisfies the following equations: H/A≤1000 and H/A+(D-H)/(1-A)≥14.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a ceramic member made of a ceramic sintered body in which an electrode and a heating resistor are embedded.

  There is a ceramic member such as a susceptor formed by joining an RF plate on which an RF electrode is installed and a heater plate on which a heating resistor is installed.

  Patent Document 1 describes that a susceptor is formed by fixing a mounting susceptor member, an upper stage susceptor plate, and a lower stage susceptor plate in a stacked state by an adhesive or heat welding. A heater (heat generating resistor) is installed in the concave heater installation space formed on the upper surface of the upper susceptor plate, and an electrode (RF electrode) for changing impedance is installed in the concave electrode installation space formed on the upper surface of the lower susceptor plate. There is.

  The mounting susceptor member and the two susceptor plates are made of quartz, the heater installation space communicates with the atmosphere, and a gap is present between the upper susceptor plate and the heater. This is because the heating by the heater to the substrate placed on the upper surface of the mounting susceptor member is a radiation heat transfer by infrared rays.

  Patent Document 2 describes that an RF electrode and a heater are embedded in a susceptor made of ceramic such as aluminum nitride.

Patent No. 4347295 JP 2001-274102 A

  However, in the susceptor described in Patent Document 1, since it is necessary to transmit infrared light, the base material of the susceptor is limited to a material which transmits infrared light such as quartz. Furthermore, since the heat generated from the heater is less likely to be conducted through the base material, the temperature of the heater may be too high to cause disconnection.

  On the other hand, as described in Patent Document 2, when the RF electrode and the heater are embedded in a susceptor whose base material is a material having a large thermal conductivity such as aluminum nitride, the heat from the heater is conducted through the base material. Although this is easy, as the operating temperature of the susceptor increases, the insulation of the aluminum nitride decreases, and a leak current is generated between the RF electrode and the heater. As a result, it becomes difficult to heat the substrate (wafer) placed on the susceptor to a desired temperature even when the predetermined power is supplied to the heater.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a ceramic member capable of easily heating a wafer to a desired temperature while suppressing the occurrence of a leak current.

  According to the present invention, there is provided a first substrate made of a ceramic sintered body having a mounting surface on which a wafer is mounted, and having an electrode embedded therein, and a second ceramic sintered body having a heating resistor embedded therein. A ceramic member in which a base is joined with a space interposed on the opposite side of the mounting surface of the first base, and the minimum height H of the space in the direction perpendicular to the mounting surface is (Mm) and a ratio A of a total area of a portion where the first base and the second base are joined to an area of a plane along the mounting surface defined by the outer edge of the mounting surface; A relationship between a distance D (mm) between the electrode and the heating resistor satisfies H / A ≦ 1000 and H / A + (D−H) / (1-A) ≧ 14. Do.

  According to the present invention, excessive inhibition of heat transfer from the heating resistor to the mounting surface is suppressed by the space interposed between the first base and the second base, and the electrode and the heating resistance are also suppressed. It is possible to suppress the occurrence of leakage current flowing between the body and the body.

  In the present invention, the relationship preferably satisfies H / A + (D-H) / (1-A) ≧ 100.

  In this case, the generation of the leak current flowing between the electrode and the heating resistor can be further suppressed.

  In the present invention, preferably, the space is at least partially filled with a medium having a thermal conductivity higher than that of air, or is connectable to a supply source of the medium.

  In this case, by controlling the pressure of the medium present in the space, it is possible to control the heat transfer between the first base and the second base while suppressing the generation of the leak current.

FIG. 1 is a schematic cross-sectional view of a ceramic heater according to an embodiment of the present invention. The schematic cross section of the ceramic heater concerning the modification of the embodiment of the present invention. The schematic cross section of the ceramic heater which concerns on the other modification of embodiment of this invention. FIG. 46 is a schematic horizontal cross-sectional view of a ceramic heater according to Example 41.

  A ceramic heater 100 according to an embodiment of the ceramic member of the present invention will be described with reference to the drawings. In the drawings described below, in order to clarify the configuration of the ceramic heater 100, each component is deformed and does not represent an actual ratio.

  As shown in FIG. 1, the ceramic heater 100 is configured by laminating an RF plate 10 having a mounting surface 11 on which a wafer (substrate), which is an object to be heated (not shown), is mounted as an upper surface, and a heater plate 20. It is done. The RF plate 10 corresponds to the first base of the present invention, and the heater plate 20 corresponds to the second base of the present invention.

  An RF electrode 30 is embedded in the RF plate 10, and a heater (heating resistor) 40 is embedded in the heater plate 20. The RF electrode 30 is a high frequency electrode used when performing plasma processing on a wafer.

  In the present embodiment, the RF electrode 30 is made of a foil such as a heat resistant metal such as molybdenum (Mo) or tungsten (W), and has a planar shape. However, the RF electrode 30 may be a film made of a heat-resistant metal or the like, a plate, a mesh, a fiber, or the like.

  The RF plate 10 and the heater plate 20 are ceramic base materials made of sintered ceramics such as alumina, aluminum nitride and silicon nitride, for example. As the RF plate 10 and the heater plate 20, an aluminum nitride sintered body having a purity of 90% or more containing a sintering aid such as yttria can be particularly preferably used. The RF plate 10 and the heater plate 20 may be prepared in a plate shape such as a disk shape by, for example, hot press baking or the like in order to form the above-described material in a mold having a predetermined shape, and form and densify it.

  In the present embodiment, the heater 40 is made of a mesh of a heat-resistant metal such as molybdenum (Mo) or tungsten (W), and has a planar shape. However, the heater 40 may be in the form of a foil, a film, a plate, a wire, a fiber, a coil, a ribbon, or the like made of a heat-resistant metal or the like.

  The RF plate 10 is fired in a state in which the RF electrode 30 is sandwiched by the ceramic material to be the RF plate 10. The heater plate 20 is fired in a state in which the heater 40 is sandwiched by the ceramic material to be the heater plate 20.

  After the RF plate 10 and the heater plate 20 are separately manufactured, they are joined such that the lower surface 12 of the RF plate 10 and the upper surface 21 of the heater plate 20 are in contact with each other. However, the lower surface 12 of the RF plate 10 and the upper surface 21 of the heater plate 20 do not contact over the entire surface, and at least a space (gap) S is interposed between the RF plate 10 and the heater plate 20. .

  The RF plate 10 and the heater plate 20 are fixed by diffusion bonding, mechanical bonding using an adhesive, fasteners such as screws, or the like.

  Further, the ceramic heater 100 is provided with a power supply terminal (power supply terminal) 31 for supplying power to the RF electrode 30, and a current supply member (not shown) embedded in the RF plate 10.

  The ceramic heater 100 also includes a power supply terminal (power supply terminal) 41 for supplying power to the heater 40 and a current supply member (not shown) embedded in the heater plate 20.

  The terminals 31, 41 and the current supply member are respectively brazed or welded. The terminals 31, 41 are rod-shaped or wire-shaped nickel (Ni), Kovar (registered trademark) (Fe-Ni-Co), molybdenum (Mo), tungsten (W), or molybdenum (Mo) and tungsten (W) Made of a heat-resistant metal such as a heat-resistant alloy mainly composed of The current supply member is made of molybdenum (Mo) or tungsten (W). The terminals 31 and 41 and the current supply member may be connected via a connection member made of a heat-resistant metal similar to the terminals 31 and 41.

  The ceramic heater 100 further includes a hollow shaft 50 connected to the center of the lower surface 22 of the heater plate 20.

  The shaft 50 has a substantially cylindrical shape, and has an enlarged diameter portion 52 in which the outer diameter of the joint portion with the heater plate 20 is larger than that of the other cylindrical portion 51, and the upper surface of the enlarged diameter portion 52 is the same as that of the heater plate 20. It is a bonding surface. The material of the shaft 50 may be equivalent to the material of the heater plate 20, but may be formed of a material having a thermal conductivity lower than that of the material of the heater plate 20 in order to enhance the heat insulation.

  The lower surface of the heater plate 20 and the upper end surface of the shaft 50 are bonded by diffusion bonding or solid phase bonding using a bonding material such as ceramic or glass. The heater plate 20 and the shaft 50 may be connected by screwing or brazing.

  In the embodiment of FIG. 1, a plurality of concave portions 23 are formed on the upper surface 21 of the heater plate 20, and a space S is formed between the concave portions 23 and the lower surface 12 of the RF plate 10. Although not shown, a concave portion may be formed on the lower surface 12 of the RF plate 10, or a concave portion may be formed on both the lower surface 12 of the RF plate 10 and the upper surface 21 of the heater plate 20. The space S may be a closed space or a space communicating with the outside, and the spaces S may or may not communicate with each other.

  The space S interposed between the RF plate 10 and the heater plate 20 suppresses the flow of leakage current from the heater 40 to the RF electrode 30.

However, since the heat generated from the heater 40 is transferred to heat the wafer supported on the mounting surface 11, the size of the space S interposed between the RF plate 10 and the heater plate 20 is more than necessary. It must not be big. The inventors set the minimum height of the space S in the direction perpendicular to the mounting surface 11 to H [mm], and the ratio of the contact area between the RF plate 10 and the heater plate 20 to A from Examples and Comparative Examples described later. It has been found that it is necessary that the following relational expression (1) be established.
H / A ≦ 1000 (1)

  The ratio A is the total area of the portion of the lower surface 12 of the RF plate 10 and the upper surface 21 of the heater plate 20 in contact with the area of the plane along the mounting surface 11 defined by the outer edge of the mounting surface 11 Ratio.

  Furthermore, as in the modified example shown in FIG. 3, a plurality of concave portions 24 are formed on the upper surface 21 of the heater plate 20, and a pin whose axial length is longer than the depth of the concave portions 24 in these concave portions 24. And the like, the upper surface 61 of the connection member 60 may be joined to the lower surface 11 of the RF plate 10, and the lower surface 62 of the connection member 60 may be joined to the bottom surface of the recess 24. As shown in FIG. 3, the bottom surface of the concave portion 24 may be formed at a position farther from the top surface 21 of the heater plate 20 than the heater 40.

  Thereby, the lower surface 12 of the RF plate 10 and the upper surface 21 of the heater plate 20 are not in contact with each other over the entire surface, and a space S existing around the connection member 60 is formed therebetween. Although not shown, a concave portion may be formed on the lower surface 12 of the RF plate 10, and the connecting member 60 may be disposed on the bottom surface, or either of the lower surface 12 of the RF plate 10 or the upper surface 21 of the heater plate 20. The connecting member 60 may be joined directly to one or both flat surfaces.

  The connecting member 60 may be made of the same material as the RF plate 10 and the heater plate 20, but may be made of a different material. The RF plate 10, the heater plate 20, and the connecting member 60 may be bonded by diffusion bonding, an adhesive, or the like. When the connecting member 60 is made of the same material as the RF plate 10 and the heater plate 20, the connecting member 60 may be integrally formed with the RF plate 10 or the heater plate 20 by cutting a ceramic base or the like. In addition, the shape of the connecting member 60 may be cylindrical, prismatic, cylindrical, or the like, and the shape is not limited, and the aspect is also not limited to the scattered point.

  In such a case, the connecting member 60 can be regarded as a member constituting a part of the first base or a part of the second base of the present invention, and the ratio A is defined by the outer edge of the mounting surface 11 Of the lower surface 12 of the RF plate 10 and the upper surface 61 of the connecting member 60, and the total of the upper surface 21 of the heater plate 20 and the lower surface 61 of the connecting member 60 It is the ratio to the area of the smaller contact area.

  Furthermore, as the RF plate 10 and the heater plate 20 are heated to a high temperature due to the heat transfer by the heat generation of the heater 40, the insulating properties of these base materials decrease. As a result, the leak current generated between the RF electrode 30 and the heater 40 increases, but if the leak current becomes excessive, the capacity of the power supply for feeding the ceramic heater 100 becomes insufficient, which makes temperature control very difficult.

Therefore, the space S is provided to suppress the occurrence of the leak current generated between the RF electrode 30 and the heater 40. The inventors set the minimum height of the space S in the direction perpendicular to the mounting surface 11 to H [mm], and the ratio of the contact area between the RF plate 10 and the heater plate 20 to A, RF from Examples and Comparative Examples described later. Assuming that the distance in the vertical direction perpendicular to the mounting surface 11 between the electrode 30 and the heater 40 is D [mm], the following relational expression (2) holds in order to suppress an excessive leak current. I found it necessary.
H / A + (D-H) / (1-A) ≧ 14 (2)

In order to further suppress the leak current, it is preferable that the following relational expression (3) is established.
H / A + (D-H) / (1-A) ≧ 100 (3)

  The distance D is a distance between the RF electrode 30 and the heater 40 in the vertical direction. The distance D has the same value when the RF electrode 30 and the heater 40 overlap or do not overlap in the vertical direction. The distance D is a distance in the vertical direction between the lower end of the RF electrode 30 and the upper end of the heater 40. For example, when the heater 40 is formed at a different position in the vertical direction, Distance.

When the shortest path not passing through the space S connecting the RF electrode 30 and the heater 40 has an overlapping portion in the vertical direction perpendicular to the mounting surface 11 as in the modification shown in FIG. D is the separation length D1 in the vertical direction between the RF electrode 30 and the heater 40 plus twice the length in the vertical direction of this overlapping portion (the distance from the bottom of the concave portion 24 to the heater 40) D2 Since it becomes, it shall be shown by Formula (4).
D = D1 + 2 × D2 (4)

  Furthermore, as in the modified example shown in FIG. 3, it is preferable that the space S be interposed between the RF electrode 30 and the heater 40 in the vertical direction. This makes it possible to effectively suppress the generation of the leak current generated between the RF electrode 30 and the heater 40. In this case, the space S may be partially interposed between the RF electrode 30 and the heater 40 in the vertical direction.

  Although not shown, a pipe may be connected to the space S, and a gas such as helium, argon, or nitrogen may be supplied from a gas supply source connected to the pipe to adjust the gas pressure of the space S. . In this case, the ease of heat transfer between the RF plate 10 and the heater plate 20 can be easily controlled by adjusting the gas pressure in the space S while suppressing the generation of the leak current. Also in this case, the space S may be a closed space or an open space.

  Further, although not shown, a reflecting plate in which a reflecting member is embedded may be added below the heater plate 20, or a reflecting member may be embedded below the heater 40 in the heater plate 20. The reflective member has an effect of suppressing the power consumption of the heater 40 by effectively reflecting the radiant heat from the heater 40. The reflecting member is made of, for example, a refractory metal such as nickel, molybdenum, tungsten, platinum, palladium, a platinum-palladium alloy, etc., and the upper surface is a mirror surface.

  Hereinafter, the present invention will be described with reference to specific examples of the present invention and comparative examples.

(Examples 1 to 40)
In Examples 1 to 40, the RF plate 10 made of an aluminum nitride (AlN) sintered body in which the RF electrode 30 is embedded and the heater plate 20 made of aluminum nitride in which the heater 40 is embedded are joined and laminated. The ceramic heater 100 shown in FIG. 1 was obtained.

[Fabrication of ceramic heater]
The RF plate 10 is made of an aluminum nitride sintered body having a diameter of 340 mm and a thickness of 4 mm and having a purity of 95% or more, and a thickness of 0.1 mm and a diameter of 300 mm. Were embedded. The aluminum nitride sintered body is added with yttria as a sintering aid.

  The heater plate 20 is made of an aluminum nitride sintered body having a diameter of 340 mm and a purity of 95% or more, and a heater 40 made of Mo mesh (wire diameter 0.1 mm, # 50, plain weave) is embedded 8 mm above the lower surface 22 . The aluminum nitride sintered body is added with yttria as a sintering aid. The heater 40 has a plurality of circular arc patterns arranged concentrically as shown in FIG. 4 and a linear pattern connecting circular arc patterns adjacent in the radial direction, and the diameter of the circular arc pattern on the outermost periphery is It was 310 mm. The heater plate 20 had a thickness of 16 mm in Examples 1 to 34 and a thickness of 26 mm in Examples 35 to 41. The volume resistivity of the aluminum nitride sintered body at 650 ° C. was 1.0 × 10 8 Ω · cm.

  A plurality of concave portions 23 were formed on the upper surface 21 of the heater plate 20 by grinding using a machining center. The height of the concave portion 23, that is, the minimum height H of the space S is 0.02 mm to 12 mm, and the ratio A of the contact area between the RF plate 10 and the heater plate 20 is 0.001 (0.1%) to It was 0.5 (50%).

  Bonding between the RF plate 10 and the heater plate 20 was performed by diffusion bonding which is heated to 1700 ° C. in vacuum while applying a pressure of 8 MPa to the bonding surface. The upper end surface of the shaft 50 made of an aluminum nitride sintered body was joined to the lower surface 22 of the heater plate 20 by diffusion bonding. Diffusion bonding at this time was performed by heating at 1600 ° C. in vacuum while applying a pressure of up to 8 MPa to the bonding surface.

  After joining the shaft 50, the nickel-made power supply terminals 31, 41 were joined to the RF electrode 30 and the heater 40 by vacuum brazing using a gold brazing material at 1000 ° C.

[Evaluation method]
The blackened dummy wafer was placed on the mounting surface 11 of the ceramic heater 100, power was supplied to the terminal 41 to raise the temperature of the heater 40, and the temperature of the surface of the dummy wafer was measured by an IR camera. From the time the surface temperature of the dummy wafer reached 600 ° C., the power supplied to the terminal 41 was made the same for 15 minutes. The RF electrode 30 was grounded.

  The temperatures of the RF plate 10 and the heater plate 20 thereafter were measured, and the difference was determined. Specifically, a thermocouple measurement hole (not shown) having a bottom at an intermediate position in the thickness direction of each of the RF plate 10 and the heater plate 20 is provided in advance in the central region of the ceramic heater 100. The temperature of the RF plate 10 and the heater plate 20 was measured by inserting a sheathed thermocouple (K type, stainless steel sheath having a diameter of 1.6 mm) into the hole.

Further, the leak current generated between the RF electrode 30 and the heater 40 was measured. The leakage current was measured by connecting an alternating current ammeter to a path between the feed terminal 31 connected to the RF electrode 30 and the ground.

[Evaluation results]
The temperature difference between the RF plate 10 and the heater plate 20 is 1.5 ° C. to 185.5 ° C., which is less than 200 ° C., H / A is 0.04 to 1000, and the relational expression (1) is satisfied. The

  The leak current generated between the RF electrode 30 and the heater 40 is 0.01 mA to 0.99 mA, which is less than 1 mA, and H / A + (D−H) / (1-A) is 14.3. To 1010, which satisfied the relational expression (2).

  Furthermore, in Examples 8, 12, 17, 18, 22, 26, 30, 34, 35, 38, the leak current generated between the RF electrode 30 and the heater 40 is 0.01 mA to 0.13 mA. There was a very small value of less than 0.15 mA, H / A + (D-H) / (1-A) was 109 to 1010, and the relational expression (3) was satisfied.

  The results of Examples 1 to 40 are summarized in Tables 1 and 2.

(Comparative example 1)
The heater plate 20 has a thickness of 20 mm, and embeds the heater 40 8 mm above the lower surface 22 thereof, and does not form the concave portion 23 on the upper surface 21 of the heater plate 20. The lower surface and the upper surface 21 of the heater plate 20 were bonded over the entire surface. The ceramic heater was manufactured as the same as Examples 1-34 except this.

[Evaluation results]
The temperature difference between the RF plate 10 and the heater plate 20 was as small as 1.5 ° C. and was good. However, the leak current generated between the RF electrode 30 and the heater 40 is as large as 1.41 mA and exceeds 1 mA.

(Comparative examples 2 to 5)
The aspect of the concave portion 23 formed on the upper surface 21 of the heater plate 20 was changed as shown in Table 3. The ceramic heater was manufactured as the same as Examples 1-34 except this.

[Evaluation results]
The temperature difference between the RF plate 10 and the heater plate 20 is 1.5 ° C. to 1.8 ° C., which is less than 200 ° C., H / A is 0.2 to 2.0, and the relational expression (1) is I met.

  The leakage current generated between the RF electrode 30 and the heater 40 was as large as 1.17 mA to 1.25 mA and exceeded 1 mA. H / A + (D-H) / (1-A) was 11.3-12.1 and did not satisfy the relational expression (2).

(Comparative Examples 6 to 11)
The aspect of the concave portion 23 formed on the upper surface 21 of the heater plate 20 was changed as shown in Table 3. Except for this, Comparative Examples 6 to 8 were the same as Examples 1 to 34, and Comparative Examples 9 to 11 were the same as Examples 35 to 40, to manufacture ceramic heaters.

[Evaluation results]
The leak current generated between the RF electrode 30 and the heater 40 was as small as 0.01 mA or less and less than 1 mA. H / A + (D-H) / (1-A) was 1208 to 12008, which satisfied the relational expression (2).

  However, the temperature difference between the RF plate 10 and the heater plate 20 exceeds 200 ° C., the H / A is 1200 to 12000, and the relational expression (1) is not satisfied.

  The results of Comparative Examples 1 to 11 are summarized in Table 3.

(Example 41)
In Example 41, it manufactured as the same as Examples 17-21 except the aspect of the concave part 23 and the shapes of the heater 40 differing.

  As shown in FIG. 4, the shape of the heater 40 is determined, and the lower surface 12 of the RF plate 10 and the upper surface 12 of the heater plate 20 are joined at a portion not overlapping the heater 40 in top view. That is, as shown in FIG. 2, the ceramic heater 100 was configured such that a space S existed between the RF electrode 30 and the heater 40. The ratio A of the contact area between the RF plate 10 and the heater plate 20 is 0.1 (10%), the minimum height H of the space S is 1.0 mm, and the vertical direction between the RF electrode 30 and the heater 40 The distance D which is the separation length at 10 mm was 10 mm.

[Evaluation results]
The temperature difference between the RF plate 10 and the heater plate 20 was as small as 3.1 ° C., which was good, and the values of the relational expressions (1) and (2) were the same as 3.1 ° C. of the same example 19.

  The leakage current generated between the RF electrode 30 and the heater 40 was as very small as 0.3 mA, which was smaller than 0.71 mA in Example 19.

(Example 42)
In Example 42, as shown in FIG. 3, a ceramic heater was manufactured in the same manner as in Examples 1 to 34 except that the RF plate 10 and the heater plate 20 were joined via the connecting member 60.

  The connecting member 60 was formed integrally with the RF plate 10 by cutting an aluminum nitride sintered body.

  The ratio A of the contact area between the RF plate 10 and the heater plate 20 and the connecting member 60 was 0.01 (1%), and the minimum height H of the space S was 1.0 mm. At this time, D1 was 5 mm, D2 was 7 mm, and D was 19 mm.

[Evaluation results]
The temperature difference between the RF plate 10 and the heater plate 20 was as small as 3.1 ° C., which was good, and H / A was 100, which satisfied the relational expression (1).

  The leak current generated between the RF electrode 30 and the heater 40 is as very small as 0.18 mA, and H / A + (D−H) / (1-A) is 118.1. Met).

(Examples 43 to 46)
In Examples 43 to 46, in the same ceramic heater 100 as in Example 18, a pipe (not shown) is connected to the space S, and helium is supplied from a helium (He) supply source connected to the pipe. The gas pressures were respectively 1 torr, 5 torr, 10 torr and 50 torr.

[Evaluation results]
In Examples 43 to 46, the temperature difference between the RF plate 10 and the heater plate 20 was as small as 19.7 ° C., 17.2 ° C., 15.2 ° C., and 12.4 ° C., respectively. When considered together with 19.7 ° C. of Example 18 in which the helium gas pressure in the space S is 0 torr, the larger the helium gas pressure in the space S, the smaller the temperature difference.

  The leak currents generated between the RF electrode 30 and the heater 40 are all 0.13 mA, which is the same as in Example 18, and the helium gas pressure in the space S does not affect the magnitude of the leak current. The

  DESCRIPTION OF SYMBOLS 10 ... RF plate (1st base | substrate), 11 ... mounting surface (upper surface), 12 ... lower surface, 20 ... heater plate (2nd base | substrate), 21 ... upper surface, 22 ... lower surface, 23, 24 ... concave part, 30 ... RF electrode (electrode), 31: feeding terminal, 40: heater (heat generating resistor), 41: feeding terminal, 50: shaft, 51: cylindrical portion, 52: enlarged diameter portion, 60: connecting member, 61: top surface, 62 ... lower surface, 100 ... ceramic heater (ceramic member), S ... space.

Claims (3)

A first base body made of a ceramic sintered body having a mounting surface on which a wafer is mounted and having an electrode embedded therein, and a second base body made of a ceramic sintered body having a heating resistor embedded therein. It is a ceramic member joined in the state which makes space intervene on the opposite side of the mounting surface of said 1st base | substrate, Comprising:
The minimum height H (mm) of the space in the direction perpendicular to the mounting surface,
A ratio A of a total area of a portion where the first base and the second base are joined to an area of a plane along the mounting surface defined by the outer edge of the mounting surface;
The relationship between the distance D (mm) between the electrode and the heating resistor is
A ceramic member characterized by satisfying H / A ≦ 1000 and H / A + (D−H) / (1−A) ≧ 14. In the ceramic member according to claim 1,
The relationship is
A ceramic member characterized by satisfying H / A + (D-H) / (1-A) ≧ 100. In the ceramic member according to claim 1 or 2,
A ceramic member, wherein the space is at least partially filled with a medium having a thermal conductivity higher than that of air, or is connectable to a supply source of the medium.