Substrate fixing device and method for manufacturing a substrate fixing device

Abstract

To improve controllability of a temperature distribution on an adsorption surface.SOLUTION: A substrate fixing device includes: a base plate; a ceramic plate; and a heat conduction member. The ceramic plate is adhered to the base plate via an adhesive agent layer, and adsorbs a substrate by an electrostatic force. The heat conduction member is arranged in an outer peripheral region overlapped with a center region overlapped with a center part of the ceramic plate in a plane view or an outer peripheral part of the ceramic plate in a plan view from at least one of an adhesive surface of the ceramic plate, an adhesive surface of the base plate, and an inner part of the adhesive agent layer, and a heat conduction ratio of the base plate and the ceramic plate to a lamination direction is higher than the heat conduction ratio of a flat surface direction vertical to the lamination direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a substrate fixing device and a method for manufacturing the substrate fixing device.

Background Art

[0002] Generally, for example, when manufacturing semiconductor components, a substrate fixing device that adsorbs and holds a wafer is also called an electrostatic chuck (ESC) and includes a ceramic plate with built-in electrodes. The substrate fixing device has a structure in which the ceramic plate is adhered to a base plate, and by applying a voltage to the electrodes built into the ceramic plate, the wafer is adsorbed to the ceramic plate using electrostatic force. By adsorbing and holding the wafer on the ceramic plate, processes such as microfabrication and etching on the wafer can be efficiently performed.

[0003] In such a substrate fixing device, the ceramic plate is adhered to the base plate by, for example, a silicone resin-based adhesive. When the ceramic plate and the base plate are adhered by an adhesive, since the thermal resistance in the thickness direction of the adhesive is relatively large, the transfer of heat from the ceramic plate that adsorbs the wafer to the base plate is inhibited, and the rapidity of temperature adjustment of the wafer may decrease. On the other hand, in order to improve the heat transfer from the ceramic plate to the base plate, a technique has been proposed in which, instead of an adhesive, the ceramic plate is adhered to the base plate by an adhesive layer composed of an aggregate of carbon nanotubes having a high longitudinal thermal conductivity.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, with the recent advancements in wafer processing miniaturization, there is a need to locally control the temperature distribution on the adsorption surface of the ceramic plate that adsorbs the wafer. For example, it is necessary to control the temperature of the central and peripheral regions of the adsorption surface of the ceramic plate to different levels.

[0006] However, when an adhesive layer consisting of an aggregate of carbon nanotubes is used, there is a problem in that heat is transferred uniformly from the entire ceramic plate to the base plate through the adhesive layer, making it difficult to control the temperature of the central and peripheral regions of the adsorption surface of the ceramic plate to be different. Specifically, because carbon nanotubes are arranged throughout the adhesive layer that bonds the ceramic plate and the base plate, the transfer of heat from the ceramic plate to the base plate is equalized, and there are limitations to improving the controllability of the temperature distribution across the entire adsorption surface of the ceramic plate.

[0007] The disclosed technology has been made in view of the above, and aims to provide a substrate fixing device and a method for manufacturing a substrate fixing device that can improve the controllability of the temperature distribution on the adsorption surface. [Means for solving the problem]

[0008] In one embodiment, the substrate fixing device disclosed in this application comprises a base plate, a ceramic plate, and a thermal conductive member. The ceramic plate is bonded to the base plate via an adhesive layer and attracts the substrate by electrostatic force. The thermal conductive member is arranged in at least one of the bonding surfaces of the ceramic plate, the bonding surface of the base plate, and inside the adhesive layer, in a central region that overlaps with the central part of the ceramic plate in a plan view or in an outer peripheral region that overlaps with the outer peripheral part of the ceramic plate in a plan view, and the thermal conductivity of the base plate and the ceramic plate in the lamination direction is higher than the thermal conductivity in the planar direction perpendicular to the lamination direction. [Effects of the Invention]

[0009] One embodiment of the substrate fixing device disclosed in this application has the effect of improving the controllability of the temperature distribution on the adsorption surface. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a perspective view showing the configuration of a substrate fixing device according to the first embodiment. [Figure 2] Figure 2 is a schematic diagram showing a cross-section of the substrate fixing device according to the first embodiment. [Figure 3] Figure 3 is a plan view showing a specific example of the arrangement of the heat conductive member and heater electrode. [Figure 4] Figure 4 is a flowchart showing a method for manufacturing a substrate fixing device according to the first embodiment. [Figure 5] Figure 5 shows a specific example of a ceramic plate. [Figure 6] Figure 6 shows a specific example of the heat-conducting member bonding process. [Figure 7] Figure 7 shows a specific example of the second adhesive application process. [Figure 8] Figure 8 shows a first modified example of the substrate fixing device according to the first embodiment. [Figure 9] Figure 9 shows a second modified example of the substrate fixing device according to the first embodiment. [Figure 10] Figure 10 shows a third modified example of the substrate fixing device according to the first embodiment. [Figure 11] Figure 11 is a schematic diagram showing a cross-section of the substrate fixing device according to the second embodiment. [Figure 12] Figure 12 is a plan view showing a specific example of the arrangement of the heat conductive member and heater electrode. [Figure 13] Figure 13 is a flowchart showing a method for manufacturing a substrate fixing device according to the second embodiment. [Figure 14] Figure 14 shows a specific example of a ceramic plate. [Figure 15] Figure 15 shows a specific example of the heat-conducting member bonding process. [Figure 16] Figure 16 shows a first modified example of the substrate fixing device according to the second embodiment. [Figure 17]FIG. 17 is a diagram showing a second modification of the substrate fixing device according to the second embodiment. [Figure 18] FIG. 18 is a diagram showing a third modification of the substrate fixing device according to the second embodiment. **Embodiments for Carrying Out the Invention**

[0011] Hereinafter, embodiments of the substrate fixing device and the method for manufacturing the substrate fixing device disclosed in the present application will be described in detail based on the drawings. Note that the disclosed technology is not limited by this embodiment.

[0012] (First Embodiment) FIG. 1 is a perspective view showing the configuration of a substrate fixing device 100 according to the first embodiment. The substrate fixing device 100 shown in FIG. 1 has a structure in which a ceramic plate 120 is adhered to a base plate 110.

[0013] The base plate 110 is a circular member made of metal such as aluminum, for example. The base plate 110 is a base material for fixing the ceramic plate 120. The base plate 110 is attached to, for example, a semiconductor manufacturing apparatus, and functions as a semiconductor holding device for holding a wafer with the substrate fixing device 100.

[0014] The ceramic plate 120 is a circular member made of insulating ceramic. The diameter of the ceramic plate 120 is smaller than the diameter of the base plate 110, and the ceramic plate 120 is fixed at the center of the base plate 110. That is, the lower surface of the ceramic plate 120 becomes an adhesive surface adhered to the base plate 1' the ceramic plate 120 is fixed by adhering the adhesive surface to the base plate 110. The upper surface of the ceramic plate 120 is an adsorption surface for adsorbing an object to be adsorbed such as a wafer, for example.

[0015] The ceramic plate 120 incorporates conductive electrodes, and utilizes the electrostatic force generated when a voltage is applied to these electrodes to attract objects such as wafers to its adsorption surface. The ceramic plate 120 also incorporates heater electrodes, and the heater electrodes, which generate heat when a voltage is applied, regulate the temperature of the ceramic plate 120 and the objects such as wafers that are attracted to the ceramic plate 120.

[0016] Figure 2 is a schematic diagram showing a cross-section of the substrate fixing device 100 according to the first embodiment. Figure 2 shows a cross-section viewed along the line II-II in Figure 1. As shown in Figure 2, the substrate fixing device 100 is constructed by bonding a base plate 110 and a ceramic plate 120 together with an adhesive layer 130.

[0017] The base plate 110 is, for example, a circular metal member with a thickness of about 20 to 50 mm. Inside the base plate 110, a refrigerant passage 111 is formed, which serves as a passage for a refrigerant such as cooling water or cooling gas. The ceramic plate 120 is cooled as the refrigerant passes through the refrigerant passage 111. As a result of the cooling of the ceramic plate 120, objects such as wafers that are adsorbed onto the adsorption surface of the ceramic plate 120 are cooled. The upper surface 110a of the base plate 110 is an adhesive surface that is bonded to the ceramic plate 120, and is bonded to the lower surface 120a of the ceramic plate 120 by an adhesive layer 130.

[0018] The ceramic plate 120 is a circular plate made of ceramic, for example, 4 to 6 mm thick. The ceramic plate 120 is obtained by firing a green sheet made using aluminum oxide, for example. The lower surface 120a of the ceramic plate 120 is an adhesive surface that is bonded to the base plate 110, and is bonded to the upper surface 110a of the base plate 110 by an adhesive layer 130. An electrode 121 and a heater electrode 122 are formed inside the ceramic plate 120.

[0019] The electrode 121 is placed inside the ceramic plate 120 and generates an electrostatic force when a voltage is applied. Due to this electrostatic force, the ceramic plate 120 attracts an object, such as a wafer, to its upper surface 120b, which serves as the adsorption surface.

[0020] The heater electrode 122 is positioned below the electrode 121 inside the ceramic plate 120 and generates heat when a voltage is applied. This heat generated by the heater electrode 122 heats the ceramic plate 120 and the object such as a wafer that is adsorbed onto the upper surface 120b of the ceramic plate 120.

[0021] The adhesive layer 130 is made of, for example, a silicone resin-based adhesive or an epoxy resin-based adhesive, and is a layer with a thickness of, for example, about 0.05 mm to 3.0 mm, and adheres the lower surface 120a of the ceramic plate 120 to the upper surface 110a of the base plate 110. A heat conductive member 140 is placed inside the adhesive layer 130.

[0022] The heat conductive member 140 has the property (hereinafter referred to as "thermal anisotropy") that the thermal conductivity in the lamination direction of the base plate 110 and the ceramic plate 120 (hereinafter sometimes simply referred to as the "lamination direction") is higher than the thermal conductivity in the planar direction perpendicular to the lamination direction. Specifically, the heat conductive member 140 has a structure in which a plurality of carbon nanotubes 141, in which the thermal conductivity in the longitudinal direction is higher than the thermal conductivity in other directions, are embedded in the resin 142. The carbon nanotubes 141 are linear crystals made of carbon and are arranged adjacent to each other so that their longitudinal direction faces the lamination direction. The thermal conductivity of the carbon nanotubes 141 in the longitudinal direction is higher than the thermal conductivity of the ceramic plate 120 and the adhesive layer 130. The resin 142 covers the carbon nanotubes 141 with both longitudinal end faces of the carbon nanotubes 141 exposed. As the resin 142, for example, a thermosetting resin such as epoxy resin or a thermoplastic resin such as polyethylene resin can be used.

[0023] Here, a specific example of the arrangement of the heat conductive member 140 and the heater electrode 122 will be explained with reference to Figure 3. Figure 3 is a plan view showing a specific example of the arrangement of the heat conductive member 140 and the heater electrode 122. In Figure 3, the arrangement of the heat conductive member 140 and the heater electrode 122 is shown as viewed from the adsorption surface (i.e., the upper surface 120b) side of the ceramic plate 120.

[0024] As shown in Figure 3, the heat conductive member 140 is positioned in a central region R1 within the adhesive layer 130 (see Figure 2) that overlaps with the center of the ceramic plate 120 in a plan view. The central region R1 is a disc-shaped region within the adhesive layer 130 that is surrounded by an annular outer region R2 that overlaps with the outer periphery of the ceramic plate 120 in a plan view. The heat conductive member 140 is formed in a disc shape corresponding to the central region R1.

[0025] By placing the thermally anisotropic heat conductive member 140 in the central region R1 rather than the entire interior of the adhesive layer 130, heat transfer from the ceramic plate 120 to the base plate 110 can be locally promoted in the central region R1. As a result, the temperature of the central part of the ceramic plate 120 can be made lower than the temperature of the outer periphery of the ceramic plate 120. Consequently, a temperature difference can be generated between the central and outer regions on the adsorption surface of the ceramic plate 120, improving the controllability of the temperature distribution on this adsorption surface.

[0026] Furthermore, as shown in Figure 3, the heater electrode 122 is built into the outer periphery of the ceramic plate 120. The heater electrode 122 is formed in an annular shape, for example, surrounding the central part of the ceramic plate 120, and does not overlap in plan view with the heat conductive member 140 which is located in the central region R1 inside the adhesive layer 130. The temperature of the outer periphery of the ceramic plate 120 can be adjusted by heating with the heater electrode 122 built into the outer periphery of the ceramic plate 120, and the temperature difference between the central part and the outer periphery of the ceramic plate 120 can be increased. As a result, the temperature difference between the central region and the outer periphery of the adsorption surface of the ceramic plate 120 can be increased, and the controllability of the temperature distribution on the adsorption surface can be further improved.

[0027] Returning to the explanation of Figure 2, the adhesive layer 130 comprises a first adhesive 131 and a second adhesive 132. The first adhesive 131 is disc-shaped and adheres the disc-shaped heat conductive member 140 to the bonding surface (i.e., the lower surface 120a) of the ceramic plate 120. The second adhesive 132 is laminated between the bonding surface (i.e., the upper surface 110a) of the base plate 110 and the bonding surface (i.e., the lower surface 120a) of the ceramic plate 120, covering the heat conductive member 140 and the first adhesive 131. The second adhesive 132 may be made of the same resin as the resin constituting the first adhesive 131, or it may be made of a different resin than the resin constituting the first adhesive 131. In this way, the heat conductive member 140 is bonded to the lower surface 120a of the ceramic plate 120 via the first adhesive 131, and the heat conductive member 140 and the first adhesive 131 are covered with the second adhesive 132, thereby fixing the position of the heat conductive member 140 within the adhesive layer 130. As a result, the heat conductive member 140 can be placed inside the adhesive layer 130 in a simple process, improving the manufacturing efficiency of the substrate fixing device 100.

[0028] Next, the manufacturing method of the substrate fixing device 100 configured as described above will be explained with reference to Figure 4. Figure 4 is a flowchart showing the manufacturing method of the substrate fixing device 100 according to the first embodiment.

[0029] First, a ceramic plate 120 for adsorbing objects such as wafers is formed (step S101). Specifically, for example, multiple green sheets mainly made of aluminum oxide are prepared, and electrodes 121 are formed on one surface of each green sheet as appropriate, and heater electrodes 122 are formed on one surface of each other green sheet. The electrodes 121 and heater electrodes 122 can be formed, for example, by screen printing a metal paste onto the surface of the green sheets. Then, the multiple green sheets are stacked and fired to form the ceramic plate 120. The ceramic plate 120 incorporates layers of electrodes 121 and layers of heater electrodes 122, for example, as shown in Figure 5. Figure 5 shows a specific example of the ceramic plate 120. The electrodes 121 are incorporated in the central and outer parts of the ceramic plate 120, and the heater electrodes 122 are incorporated only in the outer part of the ceramic plate 120. Note that the heater electrodes 122 may be omitted if necessary.

[0030] Once the ceramic plate 120 is formed, the heat conductive member 140 is bonded to the central region of the bonding surface (i.e., the lower surface 120a) of the ceramic plate 120, which overlaps with the central part of the ceramic plate 120 in a plan view (step S102). Specifically, as shown in Figure 6, for example, a disc-shaped heat conductive member 140 with a smaller diameter than the ceramic plate 120 is bonded to the central region of the lower surface 120a of the ceramic plate 120 via the first adhesive 131. Figure 6 is a diagram showing a specific example of the heat conductive member bonding process. At the time the heat conductive member 140 is bonded, the resin constituting the first adhesive 131 is in a semi-cured state. The heat conductive member 140 is bonded to the lower surface 120a of the ceramic plate 120 such that the longitudinal direction of the carbon nanotube 141 coincides with the lamination direction of the base plate 110 and the ceramic plate 120 (in other words, the thickness direction of the ceramic plate 120). At this time, the carbon nanotube 141 penetrates the resin 142 in the thickness direction, the upper end surface of the carbon nanotube 141 is in contact with the first adhesive 131, and the lower end surface of the carbon nanotube 141 is exposed from the lower surface of the resin 142.

[0031] Furthermore, if the resin constituting the first adhesive 131 is different from the resin constituting the second adhesive 132, it is preferable that the first adhesive 131 has a higher thermal conductivity than the second adhesive 132. This makes it possible to facilitate the transfer of heat from the ceramic plate 120 to the heat conductive member 140.

[0032] Then, the second adhesive is applied to the bonding surface (i.e., the upper surface 110a) of the base plate 110 (step S103). Specifically, as shown in Figure 7, for example, the second adhesive 132 is applied to the entire surface of the upper surface 110a of the base plate 110. Figure 7 is a diagram showing a specific example of the second adhesive application process. At the point when the second adhesive 132 is applied to the entire surface of the upper surface 110a of the base plate 110, the resin constituting the second adhesive 132 is in a semi-cured state.

[0033] When the second adhesive 132 is applied, the ceramic plate 120 is bonded to the base plate 110 by an adhesive layer 130 consisting of the first adhesive 131 and the second adhesive 132, which cover the heat conductive member 140 (step S104). The semi-cured second adhesive 132 is laminated on the lower surface 120a of the ceramic plate 120 so as to cover the heat conductive member 140 and the first adhesive 131, and the first adhesive 131 and the second adhesive 132 harden by heating and pressurizing. As a result, the heat conductive member 140 is positioned in the central region R1 inside the adhesive layer 130 consisting of the first adhesive 131 and the second adhesive 132, and the lower surface 120a of the ceramic plate 120 is bonded to the upper surface 110a of the base plate 110 by the adhesive layer 130. At this time, the lower end surface of the carbon nanotube 141 exposed from the lower surface of the resin 142 is connected to the upper surface 110a of the base plate 110 via the second adhesive 132, and is thermally conductive with the upper surface 110a of the base plate 110. This makes it possible to facilitate the transfer of heat from the ceramic plate 120 to the base plate 110. The substrate fixing device 100 is completed when the ceramic plate 120 is bonded to the base plate 110. Note that the upper and lower end surfaces of the carbon nanotube 141 may be embedded in the resin 142 or the adhesive layer 130.

[0034] As described above, the substrate fixing device according to the first embodiment (for example, the substrate fixing device 100) comprises a base plate (for example, base plate 110), a ceramic plate (for example, ceramic plate 120), and a heat conductive member (for example, heat conductive member 140). The ceramic plate is bonded to the base plate via an adhesive layer (for example, adhesive layer 130) and attracts the substrate by electrostatic force. The heat conductive member is positioned in a central region (for example, central region R1) inside the adhesive layer that overlaps with the central part of the ceramic plate in a plan view, and the thermal conductivity of the base plate and the ceramic plate in the stacking direction is higher than the thermal conductivity in the planar direction perpendicular to the stacking direction. As a result, the substrate fixing device according to the first embodiment can improve the controllability of the temperature distribution on the adsorption surface.

[0035] Furthermore, the heat conductive member may include carbon nanotubes (e.g., carbon nanotube 141) and a resin (e.g., resin 142). The carbon nanotubes may be arranged so that their longitudinal direction faces the stacking direction. The resin may cover the carbon nanotubes so that both ends of the carbon nanotubes in the longitudinal direction are exposed. As a result, according to the substrate fixing device of the first embodiment, heat transfer along the stacking direction between the base plate and the ceramic plate can be facilitated.

[0036] Furthermore, the adhesive layer may have a first adhesive (e.g., first adhesive 131) and a second adhesive (e.g., second adhesive 132). The first adhesive adheres the heat conductive member to the central region of the bonding surface of the ceramic plate. The second adhesive is laminated between the bonding surface of the base plate and the bonding surface of the ceramic plate, covering the heat conductive member and the first adhesive. As a result, according to the substrate fixing device of the first embodiment, the heat conductive member can be placed inside the adhesive layer in a simple process, and the manufacturing efficiency of the substrate fixing device can be improved.

[0037] Furthermore, the first adhesive may have a higher thermal conductivity than the second adhesive. This makes it possible to facilitate the transfer of heat from the ceramic plate to the heat-conducting member according to the substrate fixing device of the first embodiment.

[0038] In this embodiment, the case in which the heat conductive member 140 is placed inside the adhesive layer 130 has been described as an example, but the arrangement of the heat conductive member 140 is not limited to this and can be changed as appropriate.

[0039] Figure 8 shows a first modified example of the substrate fixing device 100 according to the first embodiment. In Figure 8, the same parts as in Figure 2 are denoted by the same reference numerals.

[0040] In the modified example shown in Figure 8, the heat conductive member 140 is placed in the central region of the adhesive surface (i.e., the lower surface 120a) of the ceramic plate 120, which overlaps with the central part of the ceramic plate 120 in a plan view, instead of the central region R1 inside the adhesive layer 130. Specifically, a recess 120c is formed in the central region of the lower surface 120a of the ceramic plate 120, and the heat conductive member 140 is placed within this recess 120c. The heat conductive member 140 may be bonded to the bottom surface of the recess 120c, for example, via adhesive 145. Even when the heat conductive member 140 is placed in the central region of the lower surface 120a of the ceramic plate 120 in this way, a temperature difference can be generated between the central region and the outer peripheral region on the adsorption surface of the ceramic plate 120, thereby improving the controllability of the temperature distribution on the adsorption surface.

[0041] Figure 9 shows a second modified example of the substrate fixing device 100 according to the first embodiment. In Figure 9, the same reference numerals are used for the same parts as in Figure 2.

[0042] In the modified example shown in Figure 9, the heat conductive member 140 is placed in the central region of the adhesive surface (i.e., the upper surface 110a) of the base plate 110, which overlaps with the central part of the ceramic plate 120 in a plan view, instead of the central region R1 inside the adhesive layer 130. Specifically, a recess 110b is formed in the central region of the upper surface 110a of the base plate 110, and the heat conductive member 140 is placed in this recess 110b. The heat conductive member 140 may be bonded to the bottom surface of the recess 110b, for example, via adhesive 145. Even when the heat conductive member 140 is placed in the central region of the upper surface 110a of the base plate 110 in this way, a temperature difference can be generated between the central region and the outer peripheral region on the adsorption surface of the ceramic plate 120, thereby improving the controllability of the temperature distribution on the adsorption surface.

[0043] Furthermore, although this embodiment describes the case in which the entire surface of the resin 142 of the heat conductive member 140 is covered with the adhesive layer 130, only the sides of the resin 142 may be covered with the adhesive layer 130.

[0044] Figure 10 shows a third modified example of the substrate fixing device 100 according to the first embodiment. In Figure 10, the same parts as in Figure 2 are denoted by the same reference numerals.

[0045] In the modified example shown in Figure 10, only the side surface of the resin 142 of the heat conductive member 140 is covered by the adhesive layer 130, and the upper surface (an example of the first surface) and lower surface (an example of the second surface) of the resin 142 are exposed from the adhesive layer 130. The upper surface of the resin 142 exposed from the adhesive layer 130 is bonded to the bonding surface (i.e., the lower surface 120a) of the ceramic plate 120, and the lower surface of the resin 142 exposed from the adhesive layer 130 is bonded to the bonding surface (i.e., the upper surface 110a) of the base plate 110. The carbon nanotubes 141 of the heat conductive member 140 have their upper end surfaces exposed from the upper surface of the resin 142 and in contact with the lower surface 120a of the ceramic plate 120, and their lower end surfaces exposed from the lower surface of the resin 142 and in contact with the upper surface 110a of the base plate 110. By doing so, the transfer of heat from the ceramic plate 120 to the base plate 110 via the heat conductive member 140 can be facilitated, and the controllability of the temperature distribution on the adsorption surface of the ceramic plate 120 can be further improved.

[0046] In the first embodiment and its various modifications described above, the case in which the heat conductive member 140 is placed on the bonding surface of the ceramic plate 120, the bonding surface of the base plate 110, or inside the adhesive layer 130 was explained as an example. However, the placement position of the heat conductive member 140 can be changed as appropriate. For example, the heat conductive member 140 may be placed on any two of the bonding surfaces of the ceramic plate 120, the bonding surface of the base plate 110, and inside the adhesive layer 130. Alternatively, the heat conductive member 140 may be placed on the bonding surface of the ceramic plate 120, the bonding surface of the base plate 110, and inside the adhesive layer 130. In short, the heat conductive member 140 may be placed on at least one of the bonding surfaces of the ceramic plate 120, the bonding surface of the base plate 110, and inside the adhesive layer 130.

[0047] (Second Embodiment) The second embodiment differs from the first embodiment mainly in the arrangement of the heat conductive member and the heater electrode.

[0048] Figure 11 is a schematic diagram showing a cross-section of the substrate fixing device 100 according to the second embodiment. In Figure 11, the same reference numerals are used for the same parts as in Figure 2. The substrate fixing device 100 shown in Figure 11 has a heat conductive member 240 instead of a heat conductive member 140.

[0049] The heat conductive member 240 is located inside the adhesive layer 130. The heat conductive member 240 has thermal anisotropy similar to the heat conductive member 140. Specifically, the heat conductive member 240 has a structure in which multiple carbon nanotubes 241 are embedded in a resin 242, and the thermal conductivity in the longitudinal direction is higher than the thermal conductivity in other directions. The carbon nanotubes 241 are linear crystals made of carbon, and are arranged adjacent to each other with their longitudinal direction facing the stacking direction. The longitudinal thermal conductivity of the carbon nanotubes 241 is higher than the thermal conductivity of the ceramic plate 120 and the adhesive layer 130. The resin 242 covers the carbon nanotubes 241 with both longitudinal end faces of the carbon nanotubes 241 exposed. As the resin 242, for example, a thermosetting resin such as epoxy resin or a thermoplastic resin such as polyethylene resin can be used.

[0050] Furthermore, a specific example of the arrangement of the heat conductive member 240 and the heater electrode 122 will be explained with reference to Figure 12. Figure 12 is a plan view showing a specific example of the arrangement of the heat conductive member 240 and the heater electrode 122. In Figure 12, the arrangement of the heat conductive member 240 and the heater electrode 122 is shown as viewed from the adsorption surface (i.e., the upper surface 120b) side of the ceramic plate 120.

[0051] As shown in Figure 12, the heat conductive member 240 is positioned in the outer peripheral region R2 within the adhesive layer 130 (see Figure 11), which overlaps with the outer peripheral portion of the ceramic plate 120 in a plan view. The outer peripheral region R2 is an annular region surrounding the disc-shaped central region R1 within the adhesive layer 130, which overlaps with the central portion of the ceramic plate 120. The heat conductive member 240 is formed in an annular shape corresponding to the outer peripheral region R2.

[0052] By placing the thermally anisotropic heat conductive member 240 in the outer peripheral region R2 rather than the entire interior of the adhesive layer 130, heat transfer from the ceramic plate 120 to the base plate 110 can be locally promoted in the outer peripheral region R2. As a result, the temperature of the outer peripheral portion of the ceramic plate 120 can be made lower than the temperature of the central portion of the ceramic plate 120. Consequently, a temperature difference can be generated between the central and outer peripheral regions on the adsorption surface of the ceramic plate 120, improving the controllability of the temperature distribution on this adsorption surface.

[0053] Furthermore, as shown in Figure 12, the heater electrode 122 is embedded in the center of the ceramic plate 120. The heater electrode 122 is formed in a triple concentric circle shape, for example, with a smaller diameter than the annular heat conductive member 240, and does not overlap with the heat conductive member 240, which is located in the outer peripheral region R2 inside the adhesive layer 130, in a plan view. By heating with the heater electrode 122 embedded in the center of the ceramic plate 120, the temperature of the center of the ceramic plate 120 can be adjusted, and the temperature difference between the center and the outer peripheral region of the ceramic plate 120 can be increased. As a result, the temperature difference between the central region and the outer peripheral region on the adsorption surface of the ceramic plate 120 can be increased, and the controllability of the temperature distribution on the adsorption surface can be further improved.

[0054] Returning to the explanation of Figure 11, the adhesive layer 130 comprises a first adhesive 131 and a second adhesive 132. The first adhesive 131 is annular in shape and adheres the annular heat conductive member 240 to the bonding surface (i.e., the lower surface 120a) of the ceramic plate 120. The second adhesive 132 is laminated between the bonding surface (i.e., the upper surface 110a) of the base plate 110 and the bonding surface (i.e., the lower surface 120a) of the ceramic plate 120, covering the heat conductive member 240 and the first adhesive 131. The second adhesive 132 may be made of the same resin as the resin constituting the first adhesive 131, or it may be made of a different resin than the resin constituting the first adhesive 131. In this way, the heat conductive member 240 is bonded to the lower surface 120a of the ceramic plate 120 via the first adhesive 131, and the heat conductive member 240 and the first adhesive 131 are covered with the second adhesive 132, thereby fixing the position of the heat conductive member 240 within the adhesive layer 130. This allows the heat conductive member 240 to be placed inside the adhesive layer 130 in a simple process, improving the manufacturing efficiency of the substrate fixing device 100.

[0055] Next, the manufacturing method of the substrate fixing device 100 configured as described above will be explained with reference to Figure 13. Figure 13 is a flowchart showing the manufacturing method of the substrate fixing device 100 according to the second embodiment. In Figure 13, the same parts as in Figure 4 are denoted by the same reference numerals.

[0056] First, a ceramic plate 120 for adsorbing an object such as a wafer is formed (step S201). Specifically, for example, multiple green sheets mainly made of aluminum oxide are prepared, and electrodes 121 are formed on one surface of the green sheets as appropriate, and heater electrodes 122 are formed on one surface of the other green sheets. The electrodes 121 and heater electrodes 122 can be formed, for example, by screen printing a metal paste onto the surface of the green sheets. Then, the multiple green sheets are stacked and fired to form the ceramic plate 120. The ceramic plate 120 incorporates layers of electrodes 121 and layers of heater electrodes 122, for example, as shown in Figure 14. Figure 14 is a diagram showing a specific example of the ceramic plate 120. The electrodes 121 are incorporated in the central and outer parts of the ceramic plate 120, and the heater electrodes 122 are incorporated only in the central part of the ceramic plate 120. Note that the heater electrodes 122 may be omitted if necessary.

[0057] Once the ceramic plate 120 is formed, the heat conductive member 240 is bonded to the outer peripheral region of the bonding surface (i.e., the lower surface 120a) of the ceramic plate 120, which overlaps with the outer peripheral portion of the ceramic plate 120 in a plan view (step S202). Specifically, as shown in Figure 15, for example, an annular heat conductive member 240 with a smaller diameter than the ceramic plate 120 is bonded to the outer peripheral region of the lower surface 120a of the ceramic plate 120 via the first adhesive 131. Figure 15 is a diagram showing a specific example of the heat conductive member bonding process. At the time the heat conductive member 240 is bonded, the resin constituting the first adhesive 131 is in a semi-cured state. The heat conductive member 240 is bonded to the lower surface 120a of the ceramic plate 120 such that the longitudinal direction of the carbon nanotube 241 coincides with the lamination direction of the base plate 110 and the ceramic plate 120 (in other words, the thickness direction of the ceramic plate 120). At this time, the carbon nanotube 241 penetrates the resin 242 in the thickness direction, the upper end surface of the carbon nanotube 241 is in contact with the first adhesive 131, and the lower end surface of the carbon nanotube 241 is exposed from the lower surface of the resin 242.

[0058] Furthermore, if the resin constituting the first adhesive 131 is different from the resin constituting the second adhesive 132, it is preferable that the first adhesive 131 has a higher thermal conductivity than the second adhesive 132. This makes it possible to facilitate the transfer of heat from the ceramic plate 120 to the heat conductive member 240.

[0059] Then, the second adhesive is applied to the bonding surface (i.e., the upper surface 110a) of the base plate 110 (step S103). Specifically, the second adhesive 132 is applied to the entire surface of the upper surface 110a of the base plate 110. At the point when the second adhesive 132 is applied to the entire surface of the upper surface 110a of the base plate 110, the resin constituting the second adhesive 132 is in a semi-cured state.

[0060] When the second adhesive 132 is applied, the ceramic plate 120 is bonded to the base plate 110 by an adhesive layer 130 consisting of the first adhesive 131 and the second adhesive 132, which cover the heat conductive member 240 (step S104). The semi-cured second adhesive 132 is laminated on the lower surface 120a of the ceramic plate 120 so as to cover the heat conductive member 240 and the first adhesive 131, and the first adhesive 131 and the second adhesive 132 harden through heating and pressurization. As a result, the heat conductive member 240 is positioned in the outer peripheral region R2 inside the adhesive layer 130 consisting of the first adhesive 131 and the second adhesive 132, and the lower surface 120a of the ceramic plate 120 is bonded to the upper surface 110a of the base plate 110 by the adhesive layer 130. At this time, the lower end surface of the carbon nanotube 241 exposed from the lower surface of the resin 242 is connected to the upper surface 110a of the base plate 110 via the second adhesive 132, and is thermally conductive with the upper surface 110a of the base plate 110. This makes it possible to facilitate the transfer of heat from the ceramic plate 120 to the base plate 110. The substrate fixing device 100 is completed when the ceramic plate 120 is bonded to the base plate 110. Note that the upper and lower end surfaces of the carbon nanotube 241 may be embedded in the resin 242 or the adhesive layer 130.

[0061] As described above, the substrate fixing device according to the second embodiment (for example, the substrate fixing device 100) comprises a base plate (for example, base plate 110), a ceramic plate (for example, ceramic plate 120), and a heat conductive member (for example, heat conductive member 240). The ceramic plate is bonded to the base plate via an adhesive layer (for example, adhesive layer 130) and attracts the substrate by electrostatic force. The heat conductive member is positioned inside the adhesive layer in an outer peripheral region (for example, outer peripheral region R2) that overlaps with the outer peripheral portion of the ceramic plate in a plan view, and the thermal conductivity of the base plate and the ceramic plate in the stacking direction is higher than the thermal conductivity in the planar direction perpendicular to the stacking direction. As a result, the substrate fixing device according to the second embodiment can improve the controllability of the temperature distribution on the adsorption surface.

[0062] Furthermore, the heat conductive member may include carbon nanotubes (e.g., carbon nanotube 241) and a resin (e.g., resin 242). The carbon nanotubes may be arranged so that their longitudinal direction faces the stacking direction. The resin may cover the carbon nanotubes so that both ends in the longitudinal direction of the carbon nanotubes are exposed. As a result, according to the substrate fixing device of the second embodiment, heat transfer along the stacking direction between the base plate and the ceramic plate can be facilitated.

[0063] Furthermore, the adhesive layer may have a first adhesive (e.g., first adhesive 131) and a second adhesive (e.g., second adhesive 132). The first adhesive adheres the heat conductive member to the outer peripheral region of the bonding surface of the ceramic plate. The second adhesive is laminated between the bonding surface of the base plate and the bonding surface of the ceramic plate, covering the heat conductive member and the first adhesive. As a result, according to the substrate fixing device of the second embodiment, the heat conductive member can be placed inside the adhesive layer in a simple process, and the manufacturing efficiency of the substrate fixing device can be improved.

[0064] Furthermore, the first adhesive may have a higher thermal conductivity than the second adhesive. This makes it possible to facilitate the transfer of heat from the ceramic plate to the heat-conducting member according to the substrate fixing device of the second embodiment.

[0065] In this embodiment, the case in which the heat conductive member 240 is placed inside the adhesive layer 130 has been described as an example, but the arrangement of the heat conductive member 240 is not limited to this and can be changed as appropriate.

[0066] Figure 16 shows a first modified example of the substrate fixing device 100 according to the second embodiment. In Figure 16, the same parts as in Figure 11 are denoted by the same reference numerals.

[0067] In the modified example shown in Figure 16, the heat conductive member 240 is placed in the outer peripheral region of the bonding surface (i.e., the lower surface 120a) of the ceramic plate 120, which overlaps with the outer peripheral portion of the ceramic plate 120 in a plan view, instead of in the outer peripheral region R2 inside the adhesive layer 130. Specifically, a recess 120c is formed in the outer peripheral region of the lower surface 120a of the ceramic plate 120, and the heat conductive member 240 is placed within this recess 120c. The heat conductive member 240 may be bonded to the bottom surface of the recess 120c, for example, via adhesive 245. Even when the heat conductive member 240 is placed in the outer peripheral region of the lower surface 120a of the ceramic plate 120 in this way, a temperature difference can be generated between the central region and the outer peripheral region on the adsorption surface of the ceramic plate 120, thereby improving the controllability of the temperature distribution on the adsorption surface.

[0068] Figure 17 shows a second modified example of the substrate fixing device 100 according to the second embodiment. In Figure 17, the same parts as in Figure 11 are denoted by the same reference numerals.

[0069] In the modified example shown in Figure 17, the heat conductive member 240 is placed in the outer peripheral region of the adhesive surface (i.e., the upper surface 110a) of the base plate 110, which overlaps with the outer peripheral portion of the ceramic plate 120 in a plan view, instead of in the outer peripheral region R2 inside the adhesive layer 130. Specifically, a recess 110b is formed in the outer peripheral region of the upper surface 110a of the base plate 110, and the heat conductive member 240 is placed in this recess 110b. The heat conductive member 240 may be bonded to the bottom surface of the recess 110b, for example, via adhesive 245. Even when the heat conductive member 240 is placed in the outer peripheral region of the upper surface 110a of the base plate 110 in this way, a temperature difference can be generated between the central region and the outer peripheral region on the adsorption surface of the ceramic plate 120, thereby improving the controllability of the temperature distribution on the adsorption surface.

[0070] Furthermore, although this embodiment describes the case in which the entire surface of the resin 242 of the heat conductive member 240 is covered with the adhesive layer 130, only the sides of the resin 242 may be covered with the adhesive layer 130.

[0071] Figure 18 shows a third modified example of the substrate fixing device 100 according to the second embodiment. In Figure 18, the same parts as in Figure 11 are denoted by the same reference numerals.

[0072] In the modified example shown in Figure 18, only the side surface of the resin 242 of the heat conductive member 240 is covered by the adhesive layer 130, and the upper surface (an example of the first surface) and lower surface (an example of the second surface) of the resin 242 are exposed from the adhesive layer 130. The upper surface of the resin 242 exposed from the adhesive layer 130 is bonded to the bonding surface (i.e., the lower surface 120a) of the ceramic plate 120, and the lower surface of the resin 242 exposed from the adhesive layer 130 is bonded to the bonding surface (i.e., the upper surface 110a) of the base plate 110. The carbon nanotubes 241 of the heat conductive member 240 have their upper end surfaces exposed from the upper surface of the resin 242 and in contact with the lower surface 120a of the ceramic plate 120, and their lower end surfaces exposed from the lower surface of the resin 242 and in contact with the upper surface 110a of the base plate 110. By doing so, the transfer of heat from the ceramic plate 120 to the base plate 110 via the heat conductive member 240 can be facilitated, and the controllability of the temperature distribution on the adsorption surface of the ceramic plate 120 can be further improved.

[0073] In the second embodiment and its various modifications described above, the case in which the heat conductive member 240 is placed on the bonding surface of the ceramic plate 120, the bonding surface of the base plate 110, or inside the adhesive layer 130 was explained as an example. However, the placement position of the heat conductive member 240 can be changed as appropriate. For example, the heat conductive member 240 may be placed on any two of the bonding surfaces of the ceramic plate 120, the bonding surface of the base plate 110, and inside the adhesive layer 130. Alternatively, the heat conductive member 240 may be placed on the bonding surface of the ceramic plate 120, the bonding surface of the base plate 110, and inside the adhesive layer 130. In short, the heat conductive member 240 may be placed on at least one of the bonding surfaces of the ceramic plate 120, the bonding surface of the base plate 110, and inside the adhesive layer 130. [Explanation of Symbols]

[0074] 100 Board fixing device 110 Base Plate 110a top surface 110b recess 111 Refrigerant passage 120 ceramic plates 120a Bottom 120b top surface 120c recess 121 Electrode 122 Heater electrodes 130 Adhesive layer 131 First Adhesive 132 Second Adhesive 140, 240 Heat conductive material 141, 241 carbon nanotubes 142, 242 resin R1 central area R2 outer area

Claims

1. base plate and A ceramic plate is bonded to the base plate via an adhesive layer and attracts the substrate by electrostatic force, A thermal conductive member is disposed in at least one of the bonding surfaces of the ceramic plate, the bonding surface of the base plate, and inside the adhesive layer, in a central region that overlaps with the central part of the ceramic plate in a plan view, or in an outer peripheral region that overlaps with the outer peripheral part of the ceramic plate in a plan view, wherein the thermal conductivity in the lamination direction between the base plate and the ceramic plate is higher than the thermal conductivity in the planar direction perpendicular to the lamination direction. It has, The aforementioned heat conductive member is Carbon nanotubes arranged such that their longitudinal direction faces the stacking direction, A resin that coats the carbon nanotube with both longitudinal ends of the carbon nanotube exposed. It has, The aforementioned heat conductive member is Displaced within the central region or the outer peripheral region of the adhesive layer, The aforementioned resin is The first surface that is bonded to the adhesive surface of the ceramic plate, A second surface which is bonded to the adhesive surface of the base plate, The side surface that connects the first surface and the second surface and is covered by the adhesive layer It has, The carbon nanotube mentioned above is One end surface is exposed from the first surface of the resin and contacts the adhesive surface of the ceramic plate, and the other end surface is exposed from the second surface of the resin and contacts the adhesive surface of the base plate. A substrate fixing device characterized by the following features.

2. A base plate and A ceramic plate is bonded to the base plate via an adhesive layer and attracts the substrate by electrostatic force, A thermal conductive member is disposed in at least one of the bonding surfaces of the ceramic plate, the bonding surface of the base plate, and inside the adhesive layer, in a central region that overlaps with the central part of the ceramic plate in a plan view, or in an outer peripheral region that overlaps with the outer peripheral part of the ceramic plate in a plan view, wherein the thermal conductivity in the lamination direction between the base plate and the ceramic plate is higher than the thermal conductivity in the planar direction perpendicular to the lamination direction. It has, The adhesive layer is A first adhesive for bonding the heat conductive member to the central region or the outer peripheral region of the bonding surface of the ceramic plate, A second adhesive is laminated between the adhesive surface of the ceramic plate and the adhesive surface of the base plate, and covers the heat conductive member and the first adhesive. It has, The first adhesive is, Higher thermal conductivity than the second adhesive A substrate fixing device characterized by the following features.

3. A base plate and A ceramic plate is bonded to the base plate via an adhesive layer and attracts the substrate by electrostatic force, A thermal conductive member is disposed in at least one of the bonding surfaces of the ceramic plate, the bonding surface of the base plate, and inside the adhesive layer, in a central region that overlaps with the central part of the ceramic plate in a plan view, or in an outer peripheral region that overlaps with the outer peripheral part of the ceramic plate in a plan view, wherein the thermal conductivity in the lamination direction between the base plate and the ceramic plate is higher than the thermal conductivity in the planar direction perpendicular to the lamination direction. It has, A recess is formed in the central region or the outer peripheral region of the adhesive surface of the ceramic plate. The aforementioned heat conductive member is Displaced within the recess A substrate fixing device characterized by the following features.

4. A base plate and A ceramic plate is bonded to the base plate via an adhesive layer and attracts the substrate by electrostatic force, A thermal conductive member is disposed in at least one of the bonding surfaces of the ceramic plate, the bonding surface of the base plate, and inside the adhesive layer, in a central region that overlaps with the central part of the ceramic plate in a plan view, or in an outer peripheral region that overlaps with the outer peripheral part of the ceramic plate in a plan view, wherein the thermal conductivity in the lamination direction between the base plate and the ceramic plate is higher than the thermal conductivity in the planar direction perpendicular to the lamination direction. It has, The aforementioned heat conductive member is At least one of the central regions located within the adhesive surface of the ceramic plate, the adhesive surface of the base plate, and the adhesive layer, The aforementioned ceramic plate is The outer circumference contains electrodes that generate heat. A substrate fixing device characterized by the following features.

5. A base plate and A ceramic plate is bonded to the base plate via an adhesive layer and attracts the substrate by electrostatic force, A thermal conductive member is disposed in at least one of the bonding surfaces of the ceramic plate, the bonding surface of the base plate, and inside the adhesive layer, in a central region that overlaps with the central part of the ceramic plate in a plan view, or in an outer peripheral region that overlaps with the outer peripheral part of the ceramic plate in a plan view, wherein the thermal conductivity in the lamination direction between the base plate and the ceramic plate is higher than the thermal conductivity in the planar direction perpendicular to the lamination direction. It has, The aforementioned heat conductive member is Displaced within the adhesive surface of the ceramic plate, the adhesive surface of the base plate, and at least one of the outer peripheral regions inside the adhesive layer, The aforementioned ceramic plate is The central part contains an electrode that generates heat. A substrate fixing device characterized by the following features.

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