TW201903936A - Ceramic member - Google Patents

Abstract

[Objective] To provide a ceramic member capable of suppressing the generation of leak current and facilitating the heating of a wafer to the desired temperature. [Means for Solution] A ceramic heater 100 includes an RF plate 10 having a placement surface 11 on which a wafer is to be placed, and made of a ceramic sintered body in which an RF electrode 30 is embedded; and a heater plate 20 made of a ceramic sintered body in which a heater 40 is embedded, the RF plate 10 and the heater plate 20 being joined to each other with a space S interposed therebetween on a side opposite to the placement surface 11 of the RF plate 10. The relationship among a minimum height H (mm) of the space S in a direction perpendicular to the placement surface 11, a proportion A of a total area of portions where the RF plate 10 and the heater plate 20 are joined, with respect to an area of a plane along the placement surface 11 that is defined by an outer edge of the placement surface 11, and a distance D (mm) between the RF electrode 30 and the heater 40, satisfies H/A1000 and H/A+(D-H)/(1-A)14.

Description

 Ceramic component  

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

Ceramic members such as a susceptor formed by joining an RF plate provided with an RF electrode and a heating plate provided with a heating resistor are already present.

Patent Document 1 describes a technique in which a carrier disk is formed by fixing a carrier disk member, an upper carrier plate, and a lower carrier plate in a state where an adhesive or a heat-welding layer is used. Further, a heater (heat generating resistor) is disposed in each of the concave heater installation spaces formed on the upper carrier plate, and an electrode capable of changing impedance is disposed on the concave electrode installation space formed on the upper carrier plate ( RF electrode).

The carrier plate member for mounting and the two carrier plates are made of quartz, and the heater installation space is in communication with the atmosphere, and there is a gap between the upper carrier plate and the heater. This is because the heating performed by the heater on the substrate placed on the substrate on which the carrier is placed is radiated by infrared rays.

Patent Document 2 describes a technique in which an RF electrode and a heater are embedded in a carrier disk made of a ceramic such as aluminum nitride.

 [Previous Technical Literature]    [Patent Literature]  

[Patent Document 1] Japanese Patent No. 4347295

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2001-274102

However, in the carrier disk disclosed in Patent Document 1, since the infrared rays must be penetrated, the substrate of the carrier is limited to a material such as quartz that allows infrared rays to penetrate. Further, since the heat generation of the heater is hard to be conducted through the substrate, there is a possibility that the heater is excessively heated and the wire is broken.

On the other hand, when the RF electrode and the heater are embedded in a carrier having a material having a large thermal conductivity such as aluminum nitride as a base material, the heat generated by the heater is easily transmitted through the substrate. However, as the use temperature of the carrier is increased, the insulation of the aluminum nitride is lowered, and a leakage current is generated between the RF electrode and the heater. As a result, even if a predetermined power is supplied to the heater, it is difficult to heat the substrate (wafer) placed on the carrier to a desired temperature.

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

The present invention is a ceramic member comprising a first substrate including a ceramic sintered body in which a wafer can be placed and a ceramic sintered body in which an electrode is embedded, and a ceramic sintered body in which a heating resistor is embedded. The second base body is formed by joining the space on the opposite side of the mounting surface of the first base body, and is characterized by a minimum height H (mm) of the space perpendicular to the mounting surface. And a ratio A of a total area of the portions of the first base body and the second base member to the plane of the mounting surface defined by the outer edge of the mounting surface, and the electrode and the heating resistor The relationship between the distances D (mm) is in accordance with the conditions of H/A ≦ 1000 and H/A + (DH) / (1-A) ≧ 14.

According to the present invention, by interposing in a space between the first substrate and the second substrate, it is possible to suppress excessive heat transfer from the heating resistor to the mounting surface, and it is possible to suppress flow to the electrode and heat generation. Leakage current between resistors.

In the present invention, the above relationship is preferably a condition conforming to H/A + (D - H) / (1 - A) ≧ 100.

In this case, it is possible to further suppress the occurrence of a leakage current flowing between the electrode and the heating resistor.

Furthermore, in the present invention, the space is preferably at least partially filled with a medium having a higher thermal conductivity than air, or may be connected to a supply source of the medium.

In this case, by controlling the pressure of the medium existing in the space, it is possible to control the heat transfer between the first substrate and the second substrate while suppressing the occurrence of the leakage current.

10‧‧‧RF board (1st base)

11‧‧‧Loading surface (above)

12‧‧‧ below

20‧‧‧heating plate (2nd base)

21‧‧‧above

22‧‧‧ below

23, 24‧‧‧ concave

30‧‧‧RF electrode (electrode)

31‧‧‧Power supply terminal

40‧‧‧heater (heating resistor)

41‧‧‧Power supply terminal

50‧‧‧Axis

51‧‧‧Cylinder

52‧‧‧Extended section

60‧‧‧Connected components

61‧‧‧above

62‧‧‧ below

100‧‧‧Ceramic heater (ceramic components)

S‧‧‧ Space

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic cross-sectional view showing a ceramic heater according to an embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view showing a ceramic heater according to a modification of the embodiment of the present invention.

Fig. 3 is a schematic cross-sectional view showing a ceramic heater according to another modification of the embodiment of the present invention.

Figure 4 is a schematic horizontal sectional view of a ceramic heater of Example 41.

 [Formation of the Invention]  

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 addition, in the drawings described below, in order to clarify the configuration of the ceramic heater 100, each constituent element is deformed, and does not represent an actual ratio.

As shown in Fig. 1, the ceramic heater 100 is composed of an RF board 10 and a heating plate 20, and the RF board 10 has a mounting surface 11 as an upper surface, and the mounting surface 11 is provided with a non-illustrated image as a heated object. Show wafer (substrate). Further, the RF board 10 corresponds to the first substrate of the present invention, and the heating plate 20 corresponds to the second substrate of the present invention.

The RF electrode 30 is embedded in the RF panel 10, and a heater (heating resistor) 40 is embedded in the heater board 20. The RF electrode 30 is a high frequency electrode used when plasma treatment is applied to the wafer.

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

The RF plate 10 and the heating plate 20 are ceramic base materials composed of a ceramic sintered body such as alumina, aluminum nitride or tantalum nitride. Since the RF plate 10 and the heating plate 20 are formed by inserting the above-mentioned material into a mold having a predetermined shape and densifying it, it is sufficient to form a plate shape such as a disk shape by, for example, hot press baking.

In the present embodiment, the heater 40 is formed of a mesh of a heat-resistant metal such as molybdenum (Mo) or tungsten (W), and is formed into a planar shape. However, the heater 40 may be formed 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 board 10 is fired in a state in which the RF electrode 30 is sandwiched by a ceramic material as the RF board 10. In addition, the heating plate 20 is fired in a state in which the heater 40 is inserted into the ceramic material as the heating plate 20.

The RF board 10 and the heating board 20 are joined to each other so that the lower surface 12 of the RF board 10 is in contact with the upper surface 21 of the heating board 20. However, the lower surface 12 of the RF panel 10 and the upper surface 21 of the heating plate 20 do not cover the entire surface contact, but at least a space (gap) S is interposed between the RF panel 10 and the heating panel 20.

The RF board 10 and the heating board 20 are fixed by mechanical bonding using a diffusion bonding, an adhesive, a screw, or the like.

Further, the ceramic heater 100 includes 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 board 10.

Further, the ceramic heater 100 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 board 20.

The terminals 31, 41 and the current supply member are respectively brazed or welded. The terminals 31 and 41 are rod-shaped or linear nickel (Ni), Kovar (registered trademark) (Fe-Ni-Co), molybdenum (Mo), tungsten (W), or molybdenum (Mo). And a heat-resistant metal such as a heat-resistant alloy containing tungsten (W) as a main component. The current supply member is made of molybdenum (Mo), tungsten (W) or the like. Further, the terminals 31 and 41 and the current supply member may be connected by a heat-resistant metal connecting member which is the same as the terminals 31 and 41.

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

The shaft 50 has a substantially cylindrical shape and has an enlarged diameter portion 52 having an outer diameter larger than a diameter of the other cylindrical portion 51, and the upper surface of the enlarged diameter portion 52 serves as a heating plate. 20 joint faces. The material of the shaft 50 may be the same as the material of the heating plate 20, but in order to improve the heat insulating property, a material having a lower thermal conductivity than the material of the heating plate 20 may be used.

The lower surface of the heating plate 20 and the upper end surface of the shaft 50 are joined by solid phase bonding by diffusion bonding or by using a bonding material such as ceramic or glass. Further, the heating plate 20 and the shaft 50 may be connected by screw fixing or brazing or the like.

In the embodiment of Fig. 1, a plurality of concave portions 23 are formed on the upper surface 21 of the heating plate 20, and a space S is formed between the concave portions 23 and the lower surface 12 of the RF panel 10. Further, a concave portion may be formed on the lower surface 12 of the RF panel 10, and a concave portion may be formed on both the lower surface 12 of the RF panel 10 and the upper surface 21 of the heating plate 20, but it is not shown. In addition, the space S may be a closed space or a space communicating with the outside, and the spaces S may or may not be connected to each other.

By the space S interposed between the RF board 10 and the heating board 20, the leakage current flows from the heater 40 to the RF electrode 30 can be suppressed.

However, since the heat transfer generated from the heater 40 must heat the wafer supported on the mounting surface 11, the size of the space S interposed between the RF board 10 and the heating plate 20 should not exceed the required size. The size. The inventors have found from the examples and comparative examples described later that the minimum height of the space S in the direction perpendicular to the mounting surface 11 is H [mm], and the ratio of the contact area between the RF board 10 and the heating plate 20 is set to A. When the following relational expression (1) must be established.

H/A≦1000‧‧‧(1)

Further, the ratio A is a ratio of a total area of the contact portion between the lower surface 12 of the RF panel 10 and the upper surface 21 of the heating plate 20 with respect to a plane area along the mounting surface 11 defined by the outer edge of the mounting surface 11.

Further, as shown in the variation of FIG. 3, a plurality of concave portions 24 may be formed on the upper surface 21 of the heating plate 20, and the concave portions 24 are provided with pins having a length in the axial direction larger than the depth of the concave portion 24. The connecting member 60 such as (Pin), the upper surface 61 of the connecting member 60 is joined to the lower surface 11 of the RF panel 10, and the lower surface 62 of the connecting member 60 may be joined to the bottom surface of the concave portion 24. Further, as shown in FIG. 3, the bottom surface of the concave portion 24 may be formed at a position farther from the upper surface 21 of the heater board 20 than the heater 40.

By this means, the contact of the lower surface 12 of the RF panel 10 with the upper surface 21 of the heating plate 20 does not cover the entire surface, but forms a space S existing around the joint member 60 therebetween. Alternatively, a concave portion may be formed on the lower surface 12 of the RF panel 10, and the connecting member 60 may be disposed on the bottom surface thereof, or the connecting member 60 may be directly bonded to the lower surface 12 of the RF panel 10 and the upper surface 21 of the heating plate 20. Flat surface of either or both sides, but not shown.

Further, the connecting member 60 may be of the same material as the RF board 10 and the heating plate 20, but may be made of different materials. The RF board 10 and the heating board 20 and the connecting member 60 can be joined by means of diffusion bonding, an adhesive, or the like. In the case where the connecting member 60, the RF plate 10, and the heating plate 20 are of the same material, the connecting member 60 may be integrally formed with the RF plate 10 or the heating plate 20 by cutting or the like of the ceramic base material. Further, the shape of the connecting member 60 may be a columnar shape, a columnar shape, a cylindrical shape, or the like, and the shape thereof is not limited, and the arrangement thereof is not limited to the scattered dot shape.

In this case, the connecting member 60 can be regarded as a member constituting one of the first base of the present invention or a part of the second base, and the ratio A is the total contact area of the lower surface 12 of the RF plate 10 and the upper surface 61 of the connecting member 60, And an area of the smaller one of the total contact areas of the upper surface 21 of the heating plate 20 and the lower surface 62 of the connecting member 60 with respect to the plane area along the mounting surface 11 defined by the outer edge of the mounting surface 11. ratio.

Further, as the RF plate 10 and the heating plate 20 are heated up by the heating action by the heat transfer by the heat generated by the heater 40, the insulation properties of these substrates are lowered. Therefore, the leakage current generated between the RF electrode 30 and the heater 40 is increased, and if the leakage current becomes excessively large, the power supply capacity for supplying power to the ceramic heater 100 is insufficient, making temperature control extremely difficult.

Therefore, a space S is provided in order to suppress leakage current generated between the RF electrode 30 and the heater 40. The inventors found out from the examples and comparative examples described later that the minimum height of the space S in the direction perpendicular to the mounting surface 11 is H [mm], and the ratio of the contact area between the RF board 10 and the heating plate 20 is set to A. When the distance between the RF electrode 30 and the heater 40 in the vertical direction perpendicular to the mounting surface 11 is D [mm], in order to suppress an excessive leakage current, the following relational expression (2) must be established.

H/A+(D-H)/(1-A)≧14‧‧‧(2)

In order to further suppress the leakage current, it is preferable to establish the following relational expression (3).

H/A+(D-H)/(1-A)≧100‧‧‧(3)

Further, the distance D is the separation length of the RF electrode 30 and the heater 40 in the vertical direction, and the RF electrode 30 and the heater 40 overlap each other in the vertical direction or do not overlap. Further, the distance D is a distance in the vertical direction from the lower end of the RF electrode 30 to the upper end of the heater 40. For example, when the heater 40 is formed at a different position in the vertical direction, it means from the upper end of the uppermost heater 40. distance.

Further, in the variation shown in FIG. 3, when the shortest path connecting the space S of the RF electrode 30 and the heater 40 has a repeating portion perpendicular to the mounting surface 11 in the vertical direction, the distance D is the RF electrode 30. The value obtained by adding the length D1 of the heater 40 in the vertical direction to the length in the vertical direction of the repeating portion (the distance from the bottom surface of the concave portion 24 to the heater 40) D2 is twice, so the value of the distance D is as follows. Formula (4).

D=D1+2×D2......(4)

Further, as shown in the variation of FIG. 3, it is preferable that a space S is interposed between the RF electrode 30 and the heater 40 in the vertical direction. With this design, the leakage current generated between the RF electrode 30 and the heater 40 can be effectively suppressed. In this case, the space S may be partially interposed between the RF electrode 30 and the heater 40 connected in the vertical direction.

Further, the piping 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 piping, and the gas pressure in the space S may be adjusted, but is not shown. In this case, the occurrence of the leakage current can be suppressed, and the ease of heat transfer between the RF board 10 and the heating plate 20 can be easily controlled by adjusting the gas pressure of the space S. Further, in this case, the space S may be a closed space or an open space.

Further, a reflecting plate in which a reflecting member is embedded may be added below the heating plate 20, and a reflecting member may be embedded below the heater 40 in the heating plate 20, but is not shown. The reflecting 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 a high-melting point metal such as nickel, molybdenum, tungsten, platinum, palladium or platinum palladium alloy, and the upper surface is a mirror-shaped member.

 [Examples]  

Hereinafter, the present invention will be specifically described by way of examples and comparative examples of the invention.

 (Examples 1 to 40)  

In the first to fourth embodiments, the RF plate 10 made of the aluminum nitride (AlN) sintered body in which the RF electrode 30 is embedded and the heating plate 40 made of the aluminum nitride in which the heater 40 is embedded are joined. The ceramic heater 100 shown in Fig. 1 was produced by lamination.

 [Production of ceramic heater]  

The RF plate 10 is composed of an aluminum nitride sintered body having a diameter of 340 mm and a thickness of 4 mm, and an RF composed of a Mo foil having a thickness of 0.1 mm and a diameter of 300 mm and a circular shape in plan view is embedded in the intermediate portion in the thickness direction. Electrode 30.

The heating plate 20 is composed of an aluminum nitride sintered body having a diameter of 340 mm, and a Mo mesh (wire diameter 0.1 mm, #50, plain weave) heater 40 is embedded above 8 mm from the lower surface 22 thereof. As shown in FIG. 4, the heater 40 has a plurality of arc-shaped patterns arranged in a concentric shape and a linear pattern in which arc-shaped patterns adjacent in the radial direction are connected to each other, and the diameter of the outermost arc-shaped pattern is as shown in FIG. It is 310mm. The heating plate 20 has a thickness of 16 mm in Examples 1 to 34 and a thickness of 26 mm in Examples 35 to 40. The volume resistivity of the aluminum nitride sintered body at 650 ° C is 1.0 × 10 ⁸ Ω. Cm.

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

The joining of the RF plate 10 and the heating plate 20 was carried out by applying a pressure of 8 MPa to the joint surface and heating to 1700 °C in a vacuum. The upper end surface of the shaft 50 formed of the aluminum nitride sintered body is joined to the lower surface 22 of the heating plate 20 by diffusion bonding. The diffusion bonding at this time is performed by heating to 1600 ° C in a vacuum while applying a pressure of 8 MPa or less to the joint surface.

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

 [evaluation method]  

A blackened dummy wafer is placed on the mounting surface 11 of the ceramic heater 100, and the terminal 41 is supplied with a power supply. The heater 40 is heated, and the temperature of the surface of the blade is measured by an IR camera. The power supplied to the terminal 41 was made the same in a period of 15 minutes from the time when the surface temperature of the blade reached 600 °C. In addition, the RF electrode 30 is grounded.

The temperature of the subsequent RF plate 10 and the heating plate 20 was measured to determine the difference. Specifically, in the central region of the ceramic heater 100, a thermoelectric pair measurement hole (not shown) having a bottom portion at an intermediate position in the thickness direction of each of the RF plate 10 and the heating plate 20 is provided in advance, and is measured by a thermoelectric pair. The temperature of the RF plate 10 and the heating plate 20 was measured by inserting a sheathed thermocouple (K type, stainless steel sheath having a diameter of 16 mm) with a hole.

Then, the leakage current occurring between the RF electrode 30 and the heater 40 is measured. The leakage current is measured by an AC current meter connected to a path between the power supply terminal 31 connected to the RF electrode 30 and the ground.

 [evaluation result]  

The temperature difference between the RF board 10 and the heating board 20 is 1.5 ° C to 185.5 ° C, as small as less than 200 ° C, and H / A is 0.04 to 1000, which is in accordance with the relationship (1).

The leakage current occurring between the RF electrode 30 and the heater 40 is 0.01 mA to 0.99 mA, as small as less than 1 mA, and H/A + (DH) / (1-A) is 14.3 to 1010, which is in accordance with the relationship (2). .

Further, in Embodiments 8, 12, 17, 18, 22, 26, 30, 34, 35, 38, the leakage current occurring between the RF electrode 30 and the heater 40 is 0.01 mA to 0.13 mA, which is very small. It is less than 0.15 mA, and H/A+(DH)/(1-A) is 109 to 1010, which is in accordance with the relationship (3).

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

 (Comparative Example 1)  

The thickness of the heating plate 20 is 20 mm, and the heater 40 is embedded above 8 mm from the lower surface 22 thereof, while the concave portion 23 is not formed on the upper surface 21 of the heating plate 20, and the space S is not provided, and the lower surface of the RF plate 10 is disposed. 12 is joined to the upper surface 21 of the heating plate 20 in a full-face manner. Further, ceramic heaters were prepared in the same manner as in Examples 1 to 34.

 [evaluation result]  

The temperature difference between the RF board 10 and the heating board 20 is as small as 1.5 ° C, which is very good. However, the leakage current generated between the RF electrode 30 and the heater 40 is as large as 1.41 mA, exceeding 1 mA.

 (Comparative Examples 2 to 5)  

The aspect of the concave portion 23 formed on the upper surface 21 of the heating plate 20 was changed as shown in Table 3. Further, a ceramic heater was prepared in the same manner as in Examples 1 to 34.

 [evaluation result]  

The temperature difference between the RF board 10 and the heating board 20 is 1.5 ° C to 1.8 ° C, as small as less than 200 ° C, and H / A is 0.2 to 2.0, which is in accordance with the relationship (1).

The leakage current generated between the RF electrode 30 and the heater 40 is as large as 1.17 mA to 1.25 mA, exceeding 1 mA. H/A+(D-H)/(1-A) is 11.3 to 12.1, which does not correspond to the relation (2).

 (Comparative Examples 6 to 11)  

The aspect of the concave portion 23 formed on the upper surface 21 of the heating plate 20 was changed as shown in Table 3. Further, Comparative Examples 6 to 8 were set to be the same as Examples 1 to 34, and Comparative Examples 9 to 11 were set to be the same as Examples 35 to 40 to obtain a ceramic heater.

 [evaluation result]  

The leakage current generated between the RF electrode 30 and the heater 40 is as small as 0.01 mA or less, and is less than 1 mA. H/A+(D-H)/(1-A) is 1208 to 12008, which is in accordance with the relationship (2).

However, the temperature difference between the RF board 10 and the heating board 20 exceeds 200 ° C, and the H/A ratio is 1200 to 12,000, which does not correspond to the relation (1).

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

 (Example 41)  

In Example 41, except that the shape of the concave portion 23 was different from that of the heater 40, the ceramic heater was obtained in the same manner as in Examples 17 to 21.

As shown in Fig. 4, the shape of the heater 40 is determined, and the lower surface 12 of the RF panel 10 is joined to the upper surface 21 of the heating plate 20 in a portion not overlapped with the heater 40 in the upper view. That is, as shown in FIG. 2, the ceramic heater 100 is configured such that a space S exists between the RF electrode 30 and the heater 40. The ratio A of the contact area of the RF board 10 and the heating board 20 is 0.1 (10%), and the minimum height H of the space S is 1.0 mm, and the distance D which is the separation length of the RF electrode 30 and the heater 40 in the vertical direction is 10 mm.

 [evaluation result]  

The temperature difference between the RF plate 10 and the heating plate 20 was as small as 3.1 ° C, which was very good, and the values of the relations (1) and (2) were the same, and were the same as the 3.1 ° C of Example 19.

The leakage current generated between the RF electrode 30 and the heater 40 was 0.3 mA, which was very small, even when compared with the 0.71 mA of Example 19.

 (Example 42)  

In Example 42, as shown in Fig. 3, a ceramic heater was produced in the same manner as in Examples 1 to 34 except that the RF plate 10 was joined to the heating plate 20 via the joining member 60.

The joining member 60 is integrally formed with the RF sheet 10 by cutting the aluminum nitride sintered body.

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

 [evaluation result]  

The temperature difference between the RF board 10 and the heating board 20 is as small as 3.1 ° C, which is very good, and H/A is 100, which is in accordance with the relationship (1).

The leakage current generated between the RF electrode 30 and the heater 40 was 0.18 mA, which was very small, and H/A+(D-H)/(1-A) was 118.1, which was in accordance with the relation (3).

 (Examples 43 to 46)  

In the ceramic heaters 100 of the same manner as in the eighteenth embodiment, the piping (not shown) is connected to the space S, and the helium gas is supplied from the helium (He) supply source connected to the piping, and the space S is provided. The helium pressures are set to 1 torr, 5 torr, 10 torr, and 50 torr, respectively.

 [evaluation result]  

In Examples 43 to 46, the temperature difference between the RF plate 10 and the heating plate 20 was as small as 19.7 ° C, 17.2 ° C, 15.2 ° C, and 12.4 ° C, respectively, which was very good. When the helium gas pressure of the space S was 0 Torr, the 19.7 ° C of Example 18 was observed, and the larger the helium pressure of the space S, the smaller the temperature difference.

The leakage current generated between the RF electrode 30 and the heater 40 was all 0.13 mA, and as in Embodiment 18, the helium pressure of the space S did not affect the magnitude of the leakage current.

Claims (3)

 A ceramic member formed by joining a first substrate and a second substrate on a side opposite to a mounting surface of the first substrate with a space interposed therebetween, wherein the first substrate has a mounting surface on which a wafer can be placed And a ceramic sintered body in which an electrode is embedded, wherein the second base system is formed of a ceramic sintered body in which a heating resistor is embedded, and is characterized in that a minimum height Hmm of the space in a direction perpendicular to the mounting surface is a ratio A of a total area of the portion of the first base body and the second base member to the plane of the mounting surface defined by the outer edge of the mounting surface, and the electrode and the heating resistor The relationship between the distances Dmm is in accordance with the conditions of H/A ≦ 1000 and H/A + (DH) / (1-A) ≧ 14.    The ceramic member of claim 1, wherein the aforementioned relationship conforms to the condition of H/A + (D - H) / (1-A) ≧ 100.    The ceramic member according to claim 1 or 2, wherein the space is configured to be at least partially filled by a medium having a higher thermal conductivity than air, or may be coupled to a supply source of the medium.