JP6532806B2 - Substrate support device - Google Patents

Description

  The present invention relates to an apparatus for supporting a substrate by a substrate, such as an electrostatic chuck that holds a substrate such as a wafer by suction on the suction surface of the substrate on which the electrostatic chuck electrode is embedded.

  An electrostatic chuck is used to hold each substrate by suction when the surfaces of a pair of similar or dissimilar substrates (wafers) are activated, and the pair of substrates are bonded at normal temperature. . In a substrate made of a substantially flat plate-like ceramic sintered body constituting an electrostatic chuck, a metal base is adhered by an adhesive to a second back surface opposite to the front surface to which a wafer is adsorbed. A flow path for circulating a cooling medium such as water is formed inside the base, and the substrate and the wafer are cooled by flowing the cooling medium through the flow path (for example, Patent Document 1) And Patent Document 2).

  In addition to a metal substrate, a metal matrix such as aluminum is used as a matrix, and a composite material in which a ceramic such as SiC is dispersed thereto is also disclosed (see, for example, Patent Document 3). A configuration has been proposed in which the groove is formed inside by a ceramic sintered body (see, for example, Patent Document 4).

JP, 2015-134714, A JP, 2015-103550, A Japanese Patent Application Laid-Open No. 10-32239 JP, 2014-9114, A

  However, when the electrostatic chuck and the metal base are joined and integrated, the cooling efficiency of the base and the substrate by the base may be insufficient due to the low thermal conductivity of the adhesive. . Therefore, it is conceivable to mechanically press-bond the base and base by bolting etc., but a gap may remain locally between the base and base, making uniform temperature control of the base difficult. .

  In addition, although it is effective to use water as the refrigerant in order to enhance the cooling efficiency, it has been necessary for the base to be a material that does not corrode water (for example, copper, brass). Therefore, water can not be used as the aluminum-based material, and instead, it has been necessary to use a mixed liquid of water and ethylene glycol having a poor heat transfer coefficient, a silicone oil, and a perfluoro-based refrigerant.

  In addition, when copper or brass is used as the base, when it is integrated with the ceramic sintered body constituting the electrostatic chuck due to elastic modulus, average coefficient of linear expansion or specific gravity, surface deformation due to external load occurs, or surface A change in shape occurred over time.

  Therefore, an object of the present invention is to provide a substrate supporting apparatus capable of improving the cooling efficiency of the substrate and the temperature uniformity. An object of the present invention is to provide a substrate supporting device which can use water as a refrigerant, has high rigidity, has high accuracy of surface shape, and is less likely to change with time.

  According to the present invention, there is provided a first base body made of a flat plate-like ceramic sintered body in which a conductor is embedded, and a second base body made of a ceramic sintered body in which a flow passage for circulating a cooling medium is formed. And a second end surface, which is an end surface of the first base, and a second end surface, which is an end surface of the second base, as a whole.

In the substrate supporting apparatus according to the present invention, at least one of the first end surface and the second end surface passes through the center thereof, and a perpendicular extending parallel to the bonding direction of the first base and the second base is used. The first end face and the second end face are mechanically crimped at a position closer to the outer peripheral edge than their respective centers, with a convex curved surface shape that gradually separates from the reference flat surface at an angle less than the reference angle. The first end face and the second end face each have a surface roughness Ra within a range of 0.01 to 0.5 [.mu.m] .

According to the substrate supporting device of the present invention, at least one of the first end surface which is one end surface of the first base and the second end surface which is one end surface of the second base is formed in a convex curved shape. Here, "convex curved surface" means the center of the end face and gradually separates from the reference plane having a perpendicular extending parallel to the bonding direction of the first base and the second base at an angle θ equal to or less than the reference angle. It means a curved surface that That is, when the angle θ is defined as a positive value range, the first derivative value dθ / dr of the angle θ (r) by the distance r from the center of the end face in the direction perpendicular to the perpendicular of the reference plane is 0 Or, it means a surface that is a positive value and whose second derivative value d ² θ / dr ² is 0 or a positive value.

  Therefore, when the first end face and the second end face are simply brought into abutment, they abut in the inner area including the center, while they are spaced apart in the annular outer area surrounding the inner area. Become. However, the first end face and the second end face are mechanically crimped at a position closer to the outer peripheral edge (position included in the outer region) than the respective centers, thereby filling the gap between the first base and the second end surface. One or both of the two substrates are in an elastically deformed state. Due to the stress of the elastic deformation, the first end face and the second end face are reliably crimped even in the inner region. In other words, when the flat end faces are mechanically crimped, a situation in which there is a gap between the end faces in the inner region is avoided. As described above, since the first end surface and the second end surface are generally joined without the use of an adhesive, the cooling medium flowing in the flow path formed in the inside of the second base (cooling plate) can be used to The cooling efficiency of the substrate and the substrate supported thereby and the temperature uniformity can be improved.

  In the substrate support apparatus according to one aspect of the present invention, when the first end face has a convex curved surface, the reference angle of the first end face is set according to the elastic modulus of the ceramic sintered body that constitutes the first base. When the second end face has a convex curved surface, the reference angle of the second end face is set in accordance with the elastic modulus of the ceramic sintered body forming the second base.

  According to the substrate supporting apparatus having the above configuration, in view of the difference in elastic modulus of the ceramic sintered body constituting each of the first base and the second base, the one or both bases are appropriately elastically deformed. Both end faces can be crimped together as a whole. For this reason, the cooling efficiency of the first substrate and the substrate supported by the first substrate can be improved while extending the life of each substrate. The reference angle may be set to be included in a range of 0.0001 to 0.002 °.

According to the substrate supporting apparatus of the present invention , as described above, the surface roughness Ra of each of the first end surface and the second end surface is included in the range of 0.01 to 0.5 μm.

  According to the substrate supporting apparatus of the above configuration, the surface roughness Ra of each end surface is adjusted to be included in an appropriate range, thereby increasing the contact area due to the anchor effect of both substrates at the time of pressure bonding, and thus the first The thermal resistance between the substrate and the second substrate is reduced. Therefore, the cooling efficiency of the first substrate and the substrate supported thereby and the temperature uniformity can be improved.

  In the substrate supporting apparatus according to one aspect of the present invention, a vapor pressure at 20 ° C. between the first end face and the second end face is 1E-05 Pa or less, desirably 1E-7 Pa or less, and a kinematic viscosity of 20 ° C. is 160 There are interposed greases, silicone oils or fluorine-based inert liquids of from 1600 cSt, preferably 160-500 cSt. When the vapor pressure is sufficiently low, diffusion into the vacuum process is suppressed, and the lower the kinematic viscosity, the easier it is to intervene between the two abutting surfaces.

  According to the substrate supporting device of the configuration, a slight gap existing between both end faces is filled with grease, silicone oil or a fluorine-based inert liquid, and the reduction of the thermal resistance between the first substrate and the second substrate is achieved. It is designed. Therefore, the cooling efficiency of the first substrate and the substrate supported thereby and the temperature uniformity can be improved.

Structure explanatory drawing of the board | substrate support apparatus as one Embodiment of this invention. Explanatory drawing regarding two bases which comprise a board | substrate support apparatus.

(Constitution)
A substrate supporting apparatus according to an embodiment of the present invention shown in FIG. 1 includes a first base 1, a second base 2, a conductor 3 embedded in the first base 1, and a first base 1 And a bolt 4 (crimping mechanism) for mechanically bonding the second base 2. In the present embodiment, the conductor 3 constitutes an electrostatic chuck electrode, and the substrate supporting device is constituted as an electrostatic chuck.

  The first substrate 1 is made of a substantially flat ceramic sintered body, and one end surface (upper end surface in FIG. 1) is a support surface on which a substrate (not shown) such as a wafer is supported. The lower end surface is a first end surface P1 to be bonded to the second base 2. The first base 1 in the present embodiment has a substantially disc shape, but may have various shapes such as a polygonal plate shape or an elliptical plate shape.

  On the supporting surface of the first base 1, a plurality of substantially cylindrical, substantially hemispherical or substantially truncated conical pins protruding from the supporting surface are regularly arranged in a triangular lattice, square lattice or concentric circle, etc. It is designed to The first base 1 is formed with a first concave portion 13 which is recessed in a substantially cylindrical shape from the first end surface P1 so as to expose a part of the conductor 3 (in the absence of the power receiving terminal 31). The number and the position of the first recess 13 are changed according to the number and the position of the conductor 3. For example, when the pair of conductors 3 constituting the electrostatic chuck electrode is embedded in the first base 1, the pair of first recesses 13 is formed in the first base 1. The first base 1 is further recessed in a substantially cylindrical shape from the other end surface, and a second concave portion 14 in which a female screw (constituting a "crimp mechanism") is formed on the side surface is formed. The second recess 14 is formed closer to the outer peripheral edge than the center of the first base 1 and is formed at each of a plurality of positions dispersed or separated in the circumferential direction.

  The conductor 3 is made of a thin plate or thin film metal and is embedded in a posture parallel to one end face of the first base 1. When the conductor 3 constitutes an electrostatic chuck electrode, a substrate such as a wafer mounted on the support surface of the first base 1 is attracted to the first base 1 by Coulomb force or the like by applying a voltage to the conductor 3. It is held. When the conductor 3 constitutes a resistance heating element, the voltage application to the conductor 3 regulates the temperature of the substrate. When the conductor 3 constitutes an electrode for applying a high frequency voltage (or an electrode for grounding), the conductor 3 and a pair thereof are embedded in the first base 1 or disposed outside the first base 1 When a high frequency voltage is applied between the ground electrodes (or high frequency voltage application electrodes), plasma such as halogen gas is generated around the substrate.

  A substantially cylindrical power receiving terminal 31 is disposed in the first recess 13 of the first base 1. The power receiving terminal 31 is formed with a substantially cylindrical recess 312 extending in the axial direction from the lower end portion thereof and having a female screw formed on the side surface. When the substrate support device is used, a substantially cylindrical power supply terminal 32 connected to a power supply (not shown) is connected to the power reception terminal 31. Specifically, an external thread formed on the side surface of the tip end portion 322 of the power supply terminal 32 and an internal thread formed on the side surface of the concave portion 312 of the power reception terminal 31 are screwed.

  The second base 2 is made of a substantially flat ceramic sintered body, and one end face (upper end face in FIG. 1) of the second base 2 is a second end face P2 to be bonded to the first base 1. The main raw material of the ceramic sintered body constituting the first base 1 and the main raw material of the ceramic sintered body constituting the second base 2 may be different or identical. The second base 2 in the present embodiment has a substantially disc shape, but may have various shapes such as a polygonal plate shape or an elliptical plate shape.

  A flow path 22 for circulating a cooling medium such as water is formed inside the second base 2. In the second base 2, a first through hole 23 for inserting the feed terminal 32 is formed at a position corresponding to the first recess 13 of the first base 1. A second through hole 24 is formed in the second base 2 at a position corresponding to the second recess 14 of the first base 1. The second through hole 24 has a counterbore formed on the other end surface (the lower end surface in FIG. 1). Thus, the second through hole 24 is formed in a substantially two-step cylindrical shape having a substantially cylindrical shape with a small diameter at one end side of the second base 2 and a substantially cylindrical shape with a large diameter at the other end side.

  The bolt 4 is inserted through the second through hole 24 of the second base 2 and screwed to the female screw formed on the side surface of the second recess 14 of the first base 1, thereby the first base 1 and the second base 2 is mechanically joined. That is, the first end face P1 and the second end face P2 are mechanically crimped at a position closer to the outer peripheral edge than the center thereof. As a result, the bonding surfaces of the first base 1 and the second base 2 are entirely crimped not only in the inner area near the center but also in the annular outer area from the outer peripheral edge.

  The first base 1 and the second base 2 are formed by screwing the second recess 14 through the through hole and the bolt inserted through the through hole and the second through hole of the second base 2 to the nut. It may be mechanically joined. In this case, in order to ensure the flatness of the substrate supported on the support surface by the first base 1, a counterbore for accommodating a bolt head or a nut is formed on the side of the support surface of the first base 1. It is also good. In addition, even if the vicinity of the outer peripheral edge of each of the first base 1 and the second base 2 is held over a plurality of places by a clamp or other pressing means, the first base 1 and the second base 2 are mechanically joined. Good. In this case, the formation of the second recess 14 in the first base 1 and the female screw on the side surface thereof and the second through hole 24 in the second base 2 may be omitted.

  In the present embodiment, the first end face P1 and the second end face P2 are formed in a convex curved shape. The respective shapes of the first end face P1 and the second end face P2 extend parallel to the bonding direction of the first base 1 and the second base 2 through the respective centers (center o in FIG. 2 / r-z coordinate system) It is defined by a reference plane P having an existing vertical line (FIG. 2 / z axis).

For example, in the first end face P1, the angle θ ₁ (r) with respect to the reference plane is designed to be 0 for 0 ≦ r ≦ r ₁ in the direction perpendicular to the perpendicular (FIG. 2 / r-axis direction) _{In the case of 1} <r ≦ R (R means the distance from the center to the outer peripheral edge), it is designed to be within the range of the first reference angle φ ₁ or less, so that the convex is gradually separated from the reference plane P. It is formed in the shape of a curved surface. When r ₁ <r ≦ R, (dθ ₁ / dr) is a continuous function with a positive range as a range, and (d ² θ ₁ / dr ² ) is a continuous function with 0 and a positive range as a range. For example, first substrate 1 may have been formed of AlN sintered body (modulus 320 [GPa]), the first reference angle phi ₁ is set in a range of 0.0001 to 0.001 °. Since the first reference angle φ ₁ is extremely small, the relationship between the gap d ₁ (r) between the reference plane P and the first end face P ₁ and the angle θ ₁ (r) is expressed by the approximate expression (10). The gap d ₁ (r) is measured, for example, using an interferometer.

θ ₁ (r) ≒ arctan (d ₁ (r) / (r−r ₁ )) .. (10).

A first reference angle phi _1, the relationship between the outer periphery of the gap D ₁ = d ₁ of the reference plane P and the first end face P1 (R) is represented by the approximation formula (12).

_{φ 1 ≒ arctan (D 1 /} (R-r 1)) ‥ (12).

For example, R = 170 [mm], the case of r = 0 [mm], the gap D ₁ is 0.3 to 3 [[mu] m].

The second end face P2 may have an angle θ ₂ (r) with respect to the reference plane in a direction perpendicular to the perpendicular, where 0 ≦ r ≦ r ₂ (r ₂ may be the same as or different from r ₁ ) Is 0, and is designed to be within the range of the second reference angle φ ₂ or less when r ₂ <r ≦ R, thereby forming a convex curved surface gradually separating from the reference plane P. . When r ₂ <r ≦ R, (dθ ₂ / dr) is a continuous function with a positive range as a range, and (d ² θ ₂ / dr ² ) is a continuous function with 0 and a positive range as a range. For example, the second substrate 2 may have been formed from SiC sintered body (modulus 420 [GPa]), the second reference angle phi ₂ is set in a range of 0.00007 to 0.001 °. Since the second reference angle phi ₁ is extremely small, and the gap d ₂ between the reference plane P and a second end face P2 (r), the relationship between the angle theta ₂ (r) is expressed by the approximation formula (20). The gap d ₂ (r) is measured, for example, using an interferometer.

θ ₂ (r) ≒ arc tan (d ₂ (r) / (r−r ₂ )) .. (20).

A second reference angle phi _2, the relationship between the reference plane P and the outer edge of the gap D ₂ = d ₂ of the second end face P2 (R) is expressed by the approximate equation (22).

_{φ 2 ≒ arctan (D 2 /} (R-r 2)) ‥ (22).

For example, R = 170 [mm], if r = 0 in [mm], the gap D ₂ is 0.2 to 3 [[mu] m].

The lower limit value of each of the angles θ ₁ (r) and θ ₂ (r) is preferably 0.00007 ° or more from the viewpoint of the measurement accuracy of the convex surface shape. One of the first end face P1 and the second end face P2 may be formed in a convex curved shape, and the other may be formed in a flat surface. The surface roughness Ra of each of the first end face P1 and the second end face P2 is included in the range of 0.01 to 0.5 [μm]. Greases may be interposed between the respective bonding surfaces of the first base 1 and the second base 2. In addition, a fluorine-based inert liquid such as silicone oil having a low vapor pressure, trade name Fluorinert, Novec (manufactured by 3M) or trade name von Brin (manufactured by SOLVAY) may be used.

(Production method)
A sintered body is produced by firing a substantially flat compact of the first raw material powder in which the conductor 3 is embedded. Then, the first base 1 is manufactured by forming the pins, the first concave portions 13 and the second concave portions 14 and the like in the sintered body according to an appropriate processing method such as blasting or machining. The power receiving terminal 31 is disposed in the first recess 13, and the upper end portion of the power receiving terminal 31 is electrically connected to the conductor 3 by brazing or the like.

  A pair of sintered bodies are produced by firing a pair of substantially flat compacts of the second raw material powder. A groove is formed on the end face of one or both of the pair of sintered bodies, and the pair of sintered bodies are joined so as to sandwich the groove, whereby the flow path 22 corresponding to the groove is formed inside The resulting conjugate is prepared. (The bonding method according to Patent Document 4 can be applied).

  A bonding material containing a ceramic powder in which the main raw material and the second raw material powder are common may be used as a bonding material of the sintered body. others. As a bonding material, glass-based bonding materials such as quartz, soda lime glass, borosilicate glass and the like may be used. The second base 2 is manufactured by forming the first through holes 23 and the second through holes 24 and the like in the joined body according to a suitable processing method such as blasting or machining.

  As the first raw material powder, for example, an aluminum nitride powder of high purity (for example, a purity of 99.9% or more), and a mixed raw material powder to which a sintering aid such as yttrium oxide powder is added as appropriate Be As a 2nd raw material powder, the silicon carbide powder of high purity (for example, purity 99.9% or more) is used, for example. Besides, other ceramic powder such as alumina powder may be used as a raw material powder. As conductor 3, for example, Mo foil or Mo mesh is used.

(Example)
Example 1
A molded body was produced from raw material powder in which 3% yttrium oxide (Y ₂ O ₃ ) was added to aluminum nitride (AlN), which is the main raw material, and this molded body was fired to produce an AlN sintered body . The thermal conductivity of the AlN sintered body was 165 [W / mK], the elastic modulus was 320 [GPa], the average linear expansion coefficient was 4.5 [ppm], and the specific gravity was 3.3. By subjecting the AlN sintered body to appropriate processing, a first substrate 1 with a diameter of 340 [mm] and a thickness of 12 [mm] was produced. The surface roughness Ra of each of the first end face P1 of the first substrate 1 and the opposite end face was adjusted to 0.05 μm. The first end face P1 is formed in a convex curved surface shape such that r ₁ = 0 [mm] and φ ₁ = 0.00051 ° (D ₁ = 1.5 [μm]). Twelve second recesses 14 arranged at equal intervals in the circumferential direction were formed.

A green body was produced from raw material powder containing silicon carbide (SiC) as a main raw material, and the green body was fired to produce a SiC sintered body. The thermal conductivity of the SiC sintered body was 150 [W / mK], the elastic modulus was 420 [GPa], the average linear expansion coefficient was 5.0 [ppm], and the specific gravity was 3.2. By subjecting the SiC sintered body to appropriate processing, a second substrate 2 having a diameter of 340 mm and a thickness of 20 mm was produced. The surface roughness Ra of each of the second end face P2 of the second substrate 2 and the opposite end face was adjusted to 0.05 μm. The second end face P2 is formed in a convex curved surface shape such that r ₂ = 0 [mm], φ ₂ = 0.00051 ° (D ₂ = 1.5 [μm]). Twelve second through holes 24 arranged at equal intervals in the circumferential direction were formed.

  The first base 1 and the second base 2 are mechanically crimped by means of twelve bolts 4 (M6, PCD. 320 [mm]) at locations equally spaced in the circumferential direction. The substrate support device of

(Example 2)
The surface roughness Ra of each of the first end face P1 of the first substrate 1 and the opposite end face was adjusted to 0.04 μm. The first end face P1 is formed in a convex curved surface shape such that r ₁ = 30 [mm] and φ ₁ = 0.0008 ° (D ₁ = 2.0 [μm]). The surface roughness Ra of each of the second end face P2 of the second substrate 2 and the opposite end face was adjusted to 0.04 [μm]. The second end face P2 is formed in a convex curved surface shape such that r ₂ = 30 [mm] and φ ₂ = 0.0006 ° (D ₂ = 1.5 [μm]). The substrate supporting device of Example 2 was configured under the same conditions as Example 1 except for these.

(Example 3)
The surface roughness Ra of each of the first end face P1 of the first base 1 and the end face opposite to the first end face was adjusted to 1.0 μm. The first end face P1 is formed in a convex curved surface shape such that r ₁ = 85 [mm], φ ₁ = 0.001 ° (D ₁ = 1.5 [μm]). The surface roughness Ra of each of the second end face P2 of the second base 2 and the opposite end face was adjusted to 1.0 μm. The second end face P2 is formed in a convex curved surface shape such that r ₂ = 85 [mm], φ ₂ = 0.0007 ° (D ₂ = 1.0 [μm]). The substrate supporting device of Example 3 was configured under the same conditions as Example 1 except for these.

(Example 4)
The surface roughness Ra of each of the first end face P1 of the first substrate 1 and the opposite end face was adjusted to 0.05 μm. The first end face P1 is formed in a convex curved surface shape such that r ₁ = 0 [mm] and φ ₁ = 0.0001 ° (D ₁ = 0.3 [μm]). The surface roughness Ra of each of the second end face P2 of the second substrate 2 and the opposite end face was adjusted to 0.05 μm. The second end face P2 is formed in a convex curved surface shape such that r ₂ = 0 [mm], φ ₂ = 0.0001 ° (D ₂ = 0.3 [μm]). The substrate supporting apparatus of Example 4 was configured under the same conditions as Example 1 except for these.

(Example 5)
The surface roughness Ra of each of the first end face P1 of the first substrate 1 and the opposite end face was adjusted to 0.05 μm. The first end face P1 is formed in a convex curved surface shape such that r ₁ = 0 [mm] and φ ₁ = 0.002 ° (D ₁ = 6.0 [μm]). The surface roughness Ra of each of the second end face P2 of the second substrate 2 and the opposite end face was adjusted to 0.05 μm. The second end face P2 is formed in a convex curved surface shape such that r ₂ = 0 [mm] and φ ₂ = 0.002 ° (D ₂ = 6.0 [μm]). The substrate supporting device of Example 5 was configured under the same conditions as Example 1 except for these.

(Example 6)
The surface roughness Ra of each of the first end face P1 of the first base 1 and the end face opposite to the first end face was adjusted to 1.0 μm. The first end face P1 is formed in a convex curved surface shape such that r ₁ = 85 [mm] and φ ₁ = 0.002 ° (D ₁ = 3.0 [μm]). The surface roughness Ra of each of the second end face P2 of the second base 2 and the opposite end face was adjusted to 1.0 μm. The second end face P2 is formed in a convex curved surface shape such that r ₂ = 85 [mm], φ ₂ = 0.0015 ° (D ₂ = 2.2 [μm]). The substrate supporting device of Example 6 was configured under the same conditions as Example 1 except for these.

(Example 7)
The surface roughness Ra of each of the first end face P1 of the first substrate 1 and the opposite end face was adjusted to 0.05 μm. The first end face P1 is formed in a convex curved surface shape such that r ₁ = 0 [mm] and φ ₁ = 0.00009 ° (D ₁ = 0.26 [μm]). The surface roughness Ra of each of the second end face P2 of the second substrate 2 and the opposite end face was adjusted to 0.05 μm. The second end face P2 is formed in a convex curved surface shape such that r ₂ = 85 [mm], φ ₂ = 0.00009 ° (D ₂ = 0.26 [μm]). The substrate supporting device of Example 7 was configured under the same conditions as Example 1 except for these.

(Example 8)
The surface roughness Ra of each of the first end face P1 of the first substrate 1 and the opposite end face was adjusted to 0.05 μm. The first end face P1 is formed in a convex curved surface shape such that r ₁ = 0 [mm] and φ ₁ = 0.0025 ° (D ₁ = 7.5 [μm]). The surface roughness Ra of each of the second end face P2 of the second substrate 2 and the opposite end face was adjusted to 0.05 μm. The second end face P2 is formed in a convex curved surface shape such that r ₂ = 85 mm and φ ₂ = 0.0025 ° (D ₂ = 7.5 μm). The substrate supporting device of Example 8 was configured under the same conditions as Example 1 except for these.

(Reference example)
The surface roughness Ra of each of the first end face P1 of the first base 1 and the opposite end face was adjusted to 0.2 μm. The first end face P1 is formed in a planar shape. In place of the second substrate 2, a cooling disk made of copper (thermal conductivity 400 W / mK, elastic modulus 120 GPa, average linear expansion coefficient 16.8 ppm, specific gravity 8.9), in which a flow path is formed, is The first substrate 1 was bonded not by mechanical pressure bonding but by an organic adhesive. The thickness of the adhesive layer was 100 μm. The substrate supporting device of Reference Example 1 was configured under the same conditions as Example 1 except for these.

(Evaluation method)
The silicon wafer (substrate) supported by the first base 1 when water as a refrigerant is flowed through the flow path 22 of the second base 2 (or the flow path of the cooling plate) at a flow rate of 5 [L / min] The overall heat transfer coefficient h ₁ [W / m ² K] with the refrigerant and the overall heat transfer coefficient h ₂ [W / m ² K] between the first base 1 and the refrigerant were measured.

In the evaluation of the overall heat transfer rate, a constant amount of heat is supplied from the upper surface of the substrate by resistance heating or lamp heating, the temperature T ₁ of the substrate, the surface temperature T ₂ of the first substrate 1 and the temperature T ₃ of the first end face P 1, The temperature T ₄ of the second end face P 2, the temperature T ₅ of the second base 2 (intermediate height of the side surface or a solid portion of the second base 2 and a position near the underlying refrigerant groove), at the inlet of the flow path 22 The temperature T ₆ of the refrigerant, the temperature T ₇ of the refrigerant at the outlet of the flow path 22, and the flow rate L of the refrigerant are measured. The temperature is measured by a contact type thermocouple directly or by converting the temperature from the emissivity of the object using an infrared camera as a non-contact means.

The amount of heat Q (W) penetrating from the substrate to the cooling plate (second base 2) is estimated from the temperature difference (T ₆ -T ₅ ) of the refrigerant at the inlet and outlet of the flow path 22, the flow rate of the refrigerant and the specific heat of the refrigerant .
At this time, the overall heat transfer coefficient h ₁ between the substrate and the refrigerant is estimated by the following equation (31). Here, S is the area of the substrate.

_{h 1 = Q / {S (} T 1 -T 6)} ‥ (31).

Similarly, the overall heat transfer coefficient h ₂ between the surface of the first substrate 1 and the refrigerant is estimated by the following equation (32).

_{h 2 = Q / {S (} T 2 -T 6)} ‥ (32).

The evaluation results are shown together in Table 1.

  According to the substrate support device (electrostatic chuck) having the above-described configuration, each of the first end surface P1 and the second end surface P2 is formed in a convex curved surface. Therefore, when the first end face P1 and the second end face P2 are simply brought into abutment, they abut in the inner area including the center, while there is a gap in the annular outer area surrounding the inner area. (See Figure 2). However, the female screw formed in the bolt 4 and the second recess 14 of the first base 1 at a position where the first end surface P1 and the second end surface P2 are closer to the outer peripheral edge than the respective centers (a position included in the outer region). Mechanically crimped by screwing

  Thereby, both of the first base 1 and the second base 2 are elastically deformed so as to fill the gap, and the stress of the elastic deformation ensures that the first end face P1 and the second end face P2 are crimped also in the inner region . As described above, since the first end face P1 and the second end face P2 are entirely joined without an adhesive, the cooling medium flowing through the flow path 22 formed inside the second base 2 (cooling board) Thus, the cooling efficiency of the first substrate 1 and the substrate supported thereby and the temperature uniformity can be improved.

  Further, since the thermal resistances of the first base 1 and the second base 2 can be reduced, the temperature of the substrate supported by the first base 1 is set to the temperature of water as the refrigerant flowing through the flow path 22 of the second base 2. It can be approached. Since a high rigidity material such as SiC can be used for the second base 2, it is possible to reduce the deformation of the surface due to the external load. By reducing the difference in linear expansion between the first substrate 1 and the second substrate 2, residual stress is suppressed, and a structure having excellent shape stability with a small secular change is obtained. Moreover, it was possible to make it a lightweight structure from high specific rigidity.

1 .. first substrate, 2 .. second substrate, 3 .. conductor, 4 .. bolt (crimp mechanism), 31 .. power receiving terminal, 32 .. feeding terminal, P .. reference plane, P1 .. first end face, P2 .. second End face.

Claims (4)

A first substrate made of a flat ceramic sintered body in which a conductor is embedded;
And a second base body made of a ceramic sintered body in which a flow passage for circulating a cooling medium is formed.
It is a substrate supporting device constituted by joining the 1st end face which is one end face of said 1st base, and the 2nd end face which is 1 end of said 2nd base in general.
At least one of the first end surface and the second end surface has a perpendicular line extending parallel to the bonding direction of the first base and the second base through the center thereof and having a reference angle or less It is formed in the shape of a convex curved surface that gradually separates at an angle,
It further comprises a crimping mechanism for mechanically crimping the first end face and the second end face at positions closer to the outer peripheral edge than their respective centers ,
The substrate supporting device characterized in that the surface roughness Ra of each of the first end surface and the second end surface is included in the range of 0.01 to 0.5 [μm] . In the substrate support apparatus according to claim 1,
When the first end face has a convex curved surface, the reference angle of the first end face is set according to the elastic modulus of the ceramic sintered body that constitutes the first base, and the second end face has a convex curved surface. In this case, the reference angle of the second end face is set in accordance with the elastic modulus of the ceramic sintered body forming the second base. The substrate support apparatus according to claim 1 or 2
A substrate support apparatus, wherein the reference angle is set to be included in a range of 0.0001 to 0.002 °. The substrate support apparatus according to any one of claims 1 to 3 .
A substrate supporting device characterized in that grease, silicone oil or a fluorine-based inert liquid is interposed between the first end face and the second end face.