Electrostatic chuck module

Abstract

To provide an electrostatic chuck module which is operated at a temperature higher than or equal to a heatproof temperature of a resin.SOLUTION: An electrostatic chuck module comprises: a base including a passage which allows a refrigerant to flow at a lower part and including a recessed part and a protruding part disposed at an outer periphery of the recessed part at an upper part; a heat insulation material disposed in the recessed part of the base; a resistance heating element disposed on or inside the heat insulation material; a soaking plate disposed on the heat insulation material and the resistance heating element; and a ceramic plate which is disposed on the soaking plate and includes an electrode for suctioning a processed body with static electricity. The protruding part of the base is joined to the soaking plate.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electrostatic chuck module. [Background technology]

[0002] An electrostatic chuck module that operates at high temperatures has been developed. In Patent Document 1, an electrostatic chuck includes a metal base having a flow path for flowing a coolant for cooling and having a base surface and a base back surface, a main substrate made of ceramics and disposed on the base surface side of the metal base, and an adsorption electrode disposed on the main substrate. The electrostatic chuck further includes a heater disposed on the main substrate, and an adhesive layer disposed between the metal base and the main substrate. The main substrate includes a heat insulating layer disposed on the metal base side of the heater. The heat insulating layer is provided with a plurality of minute spaces disposed at predetermined intervals from each other on the same plane. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-72477 A Summary of the Invention [Problem to be solved by the invention]

[0004] The electrostatic chuck of Patent Document 1 operates at high temperatures of 150° C. or higher. However, the electrostatic chuck of Patent Document 1 uses a silicone resin for an adhesive layer for fixing high-temperature components, and inevitably cannot withstand temperatures higher than the heat-resistant temperature of the resin. Therefore, an object of the present disclosure is to provide an electrostatic chuck module that includes a base for cooling and operates at temperatures higher than the heat-resistant temperature. [Means for solving the problem]

[0005] The electrostatic chuck module of the present disclosure comprises: A base having a flow path through which a coolant can flow in a lower portion thereof, and having a recess in an upper portion thereof and a protrusion disposed on an outer periphery of the recess; A heat insulating material disposed in the recess of the base; A resistive heating element disposed on or within the thermal insulation material; A heat spreader plate disposed on the heat insulating material and the resistance heating element; a ceramic plate disposed on the heat equalizing plate and having an electrode for attracting the workpiece by static electricity; The protruding portion of the base is joined to the heat equalizing plate and is an electrostatic chuck module.

[0006] With the above configuration, it is possible to provide an electrostatic chuck module that operates at a temperature equal to or higher than the heat-resistant temperature of the resin.

[0007] The electrostatic chuck module of the present disclosure comprises: The resistive heating elements are multiple, The plurality of resistive heating elements are arranged in a concentric circle shape, The multiple resistance heating elements can be independently heated to a temperature of 300° C. or higher.

[0008] With the above-described configuration, the operating temperature of the electrostatic chuck module can be controlled to 300° C. or higher, and the temperature of the workpiece mounted on the surface of the ceramic plate can be highly uniformly controlled.

[0009] The electrostatic chuck module of the present disclosure comprises: The difference between the thermal expansion coefficient of the ceramic plate and the thermal expansion coefficient of the electrostatic chuck of the heat equalizer plate at the operating temperature is ±2×10 -6 / K.

[0010] With the above-mentioned configuration, the stress acting on the ceramic plate due to thermal expansion can be kept below a predetermined value, and damage to the ceramic plate can be prevented.

[0011] The electrostatic chuck module of the present disclosure comprises: The width of the joint between the protrusion of the base and the heat equalizing plate is 2 mm or more and 5 mm or less.

[0012] With the above-described configuration, it is possible to suppress temperature variations in the heat equalizing plate and to reduce surface distortion of the heat equalizing plate.

[0013] The electrostatic chuck module of the present disclosure comprises: The heat spreader plate is directly or indirectly bonded to the heat insulating material using an inorganic adhesive.

[0014] With the above-mentioned configuration, the heat equalizing plate can maintain adhesion at high temperatures equal to or higher than the heat resistance temperature of the insulating material and the resin.

[0015] The electrostatic chuck module of the present disclosure comprises: The heat spreader is characterized in that an insulator is interposed between the heat spreader plate and the heat insulating material, and the resistance heating element is not in direct contact with the heat spreader plate.

[0016] With the above-mentioned configuration, the metal heat equalizing plate does not come into direct contact with the resistance heating element that generates heat by electricity, and a short circuit does not occur.

[0017] The electrostatic chuck module of the present disclosure comprises: The present invention is characterized in that a labyrinth structure is disposed under the protruding portion of the base.

[0018] With the above-described configuration, the amount of heat transferred from the heat equalizing plate to the base can be reduced, and the temperature variation on the surface of the heat equalizing plate is improved, resulting in improved thermal uniformity of the electrostatically attracted workpiece.

[0019] The electrostatic chuck module of the present disclosure comprises: The heat equalizing plate is fixed to the base by a fastening member. A disc spring or a part having a spring force may be used as an auxiliary.

[0020] With the above-described configuration, the surface distortion of the electrostatic chuck module can be reduced. Effect of the Invention

[0021] According to the present disclosure, it is possible to provide an electrostatic chuck module that can operate at temperatures equal to or higher than the heat resistance temperature of the resin. The electrostatic chuck module of the present disclosure can be used at temperatures of 450° C. or higher in particular. [Brief description of the drawings]

[0022] [Figure 1] 1 is a schematic diagram of an electrostatic chuck module according to an embodiment; [Diagram 2] FIG. 2 is an enlarged view of an electrostatic chuck module according to an embodiment. [Diagram 3] FIG. 13 is an enlarged view of an electrostatic chuck module according to another embodiment. [Figure 4] 1 is a diagram showing the relationship between the thermal expansion coefficient and temperature of a material of an electrostatic chuck module according to an embodiment. FIG. [Diagram 5] 1 is a diagram showing the relationship between the difference in thermal expansion coefficient between materials of an electrostatic chuck module according to an embodiment and the stress generated between the materials. FIG. [Figure 6] 11A and 11B are diagrams illustrating a convex portion thickness and a simulated structure of the electrostatic chuck module according to the embodiment. [Figure 7] 11 is a diagram showing a simulation result of a relationship between a thickness of a protrusion of an electrostatic chuck module according to an embodiment and a temperature variation of a heat equalizing plate and a surface distortion. FIG. [Figure 8] 1 is a schematic diagram showing an electrostatic chuck module according to an embodiment fixed by a fastening member; [Figure 9] 13A and 13B are diagrams showing simulation results of the relationship between surface distortion when the electrostatic chuck module according to the embodiment is not fixed with a fastening member and when it is fixed with a fastening member; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the invention according to the claims is not limited to the following embodiment. Furthermore, not all of the configurations described in the embodiment are necessarily essential as means for solving the problem. For clarity of explanation, the following description and drawings are omitted and simplified as appropriate. In each drawing, the same elements are given the same reference numerals, and repeated explanations are omitted as necessary.

[0024] (Description of the Configuration of the Electrostatic Chuck Module According to the Embodiment) Fig. 1 is a schematic diagram of an electrostatic chuck module according to an embodiment. Fig. 2 is an enlarged view of an electrostatic chuck module according to an embodiment. Fig. 3 is a schematic diagram of an electrostatic chuck module according to another embodiment. The configuration of an electrostatic chuck module according to an embodiment will be described with reference to Fig. 1. The electrostatic chuck module 100 is a module that holds a wafer substrate by using static electricity in an etching process during the manufacture of a semiconductor DRAM (Dynamic Random Access Memory), for example.

[0025] 1 to 3, the electrostatic chuck module 100 includes a base 101, a heat insulating material 102, a resistance heating element 106, a heat spreader plate 103, and a ceramic plate 104. The electrostatic chuck module 100 may further include an insulator 108.

[0026] The base 101 is a base having a cooling function. The base 101 has a cooling function to prevent the heat of the high-temperature heat equalizing plate from being transferred to the lower part of the electrostatic chuck module. The base 101 has a flow path 101d for flowing a coolant, a convex portion 101b, and a concave portion 101a. The base 101 also has a labyrinth structure 101c. The base 101 is made of, for example, titanium.

[0027] The coolant flows through flow passage 101d, thereby keeping the lower surface of electrostatic chuck module 100 at the same temperature as the coolant. The recess 101a and protrusion 101b are formed in order to contain heat insulating material 102 and the like in base 101. Therefore, protrusion 101b is disposed on the outer periphery of recess 101a.

[0028] The protruding portion 101b is joined to the heat equalizing plate 103. The protruding portion 101b dissipates heat transmitted from the heat equalizing plate 103. The protruding portion 101b is joined to the heat equalizing plate 103 by any one of brazing, diffusion bonding, ultrasonic welding, electric welding, and welding.

[0029] The labyrinth structure 101c is disposed under the protruding portion 101b of the base 101. The labyrinth structure 101c adjusts the amount of heat transferred from the heat equalizing plate 103 to the base 101. The outer surface of the base 101 is made of aluminum oxide (Al 2 O 3 ) A thermal spray coating is formed (not shown).

[0030] The heat insulating material 102 is disposed in the recess 101a of the base 101. The heat insulating material 102 blocks the transfer of heat. The thermal conductivity of the heat insulating material is desirably 1 W / m·K or less in the operating temperature range. The heat insulating material 102 is disposed between the heat equalizing plate 103 and the base 101 so that the heat of the resistance heating element 106 is not transferred directly to the base 101. When the surface of the heat insulating material 102 facing the base 101 becomes lower than 300° C., the heat insulating material 102 may be bonded to the base 101 with a silicone adhesive. When the surface becomes higher than 300° C., the heat insulating material 102 may be bonded to the base 101 with an inorganic adhesive.

[0031] The resistance heating element 106 is disposed between the heat insulating material 102 and the inorganic adhesive 105. The resistance heating element 106 is in a sheet shape. The resistance heating element 106 is disposed in a groove formed in the heat insulating material 102. The resistance heating element 106 may be disposed on the heat insulating material 102 or may be disposed inside the heat insulating material 102. When the resistance heating element 106 is disposed inside the heat insulating material 102, it is preferable that the resistance heating element 106 is disposed closer to the heat equalizing plate 103 than the base 101 and above the middle of the heat insulating material 102 in the vertical direction. The resistance heating element 106 generates heat by passing electricity. There may be a plurality of resistance heating elements 106. The plurality of resistance heating elements 106 may be disposed in a concentric circular shape. These plurality of resistance heating elements 106 can be independently heated to a temperature of, for example, 300° C. or higher. In this manner, the surface of the electrostatic chuck module 100 can be heated to a temperature of 300° C. or higher and 600° C. or lower, and the temperature can be kept uniform. It is also important that inorganic adhesive 105 is interposed between resistance heating element 106 and heat equalizing plate 103 so that resistance heating element 106 does not come into direct contact with heat equalizing plate 103, which is made of metal, and thus does not short out.

[0032] The heat spreader plate 103 is placed on the heat insulating material 102 and the resistance heating element 106. The heat spreader plate 103 has the function of uniformly distributing heat from the resistance heating element 106. The heat spreader plate 103 is a metal having a thermal conductivity of 100 W / m·K or more, and a material is selected for which the difference between the thermal expansion coefficient of the heat spreader plate 103 and that of the ceramic plate 104 is small. The heat spreader plate 103 is made of, for example, molybdenum. Molybdenum has a thermal expansion coefficient of 5.1×10 -6 / K and the thermal conductivity is 118 W / m K at 527 °C.

[0033] As shown in FIG. 2, the heat spreader plate 103 is bonded to the heat insulating material 102 using an inorganic adhesive 105. Alternatively, as shown in FIG. 3, the surface of the heat spreader plate 103 facing the heat insulating material 102 is coated with aluminum oxide (Al 2 O 3 The outer surface of the heat spreader plate 103 may be made of aluminum oxide (Al 2 O 3) a thermal spray coating is formed (not shown). Therefore, the heat spreader plate is directly or indirectly bonded to the heat insulating material using an inorganic adhesive. Also, an insulating plate with inorganic adhesive 105 applied on both sides may be sandwiched between the heat spreader plate 103 and the heat insulating material 102 (not shown).

[0034] The ceramic plate 104 is placed on the heat equalizing plate 103. The ceramic plate 104 includes an electrode 107 for attracting an object to be processed, such as a wafer substrate, by static electricity. The ceramic plate 104 is made of, for example, aluminum oxide (Al 2 O 3 ) Aluminum oxide has a thermal expansion coefficient of 5.4 × 10 -6 / K and the thermal conductivity is 11.4 W / m K at 500 °C.

[0035] The electrostatic chuck module 100 is manufactured by the following steps. First, a titanium plate is machined to form grooves that will become flow paths, and then joined with a metal brazing material to contain the flow paths. Next, the titanium plate is machined to form the required shape. Next, the required insulating parts are joined to the ceramic plate 104. Next, the required insulating parts are joined to the heat equalizing plate 103. Next, the ceramic plate 104 and the heat equalizing plate 103 are joined by brazing or the like.

[0036] Next, the heat insulating material 102 is machined to form the necessary shape, such as a groove into which the resistance heating element 106 is inserted. Next, a power supply terminal is attached to the end of the resistance heating element 106 by welding or the like. Next, the resistance heating element 106 is placed along the groove of the heat insulating material 102. Next, the resistance heating element 106 is attached to the heat equalizing plate 103 and the insulator 108 sandwiched therebetween by inorganic adhesive 105. Next, silicone adhesive or inorganic adhesive 105 is applied to the back surface of the heat insulating material 102, and the heat insulating material 102 is bonded to the base 101. At this time, a screw with one or more disc springs sandwiched between them may be tightened to fix the base 101 and the heat equalizing plate 103.

[0037] Next, the heat equalizing plate 103 is joined to the base 101 by brazing, welding, or the like. If there is a protrusion at the joint, the joint surface is smoothed by processing. Next, Al 2 O 3 Thermal spraying is applied to the necessary surfaces of the heat equalizing plate 103 and the base 101. Next, a defect inspection is performed on the electrostatic chuck module 100 from the ceramic plate 104 side of the electrostatic chuck module 100 using an ultrasonic flaw detector. If there are no major defects between the laminates and the bonding area is 99% or more, it is considered to pass. Next, a current is passed through the heating mechanism of the electrostatic chuck module 100 to confirm that the object to be treated reaches 300°C or higher. After this, a defect inspection is performed again on the electrostatic chuck module 100 using the ultrasonic flaw detector to confirm that there is no change from after bonding. The pass criteria here are the same as those before the heating test.

[0038] The above-described configuration provides an electrostatic chuck module that can heat a substrate that is attracted and fixed to the electrostatic chuck to 300° C. or higher, can rapidly heat and cool the substrate, and can prevent damage to the substrate or ceramic plate.

[0039] In a configuration in which the base is not joined to the heat equalizing plate, the amount of heat that escapes from the heat equalizing plate to the base is small, and the temperature of the surface of the electrostatic chuck module is difficult to decrease. However, by joining the base 101 to the heat equalizing plate 103, heat can easily flow from the heat equalizing plate 103 to the base 101. Therefore, when the resistance heating element 106 is turned off, the temperature of the surface of the electrostatic chuck module can be decreased quickly.

[0040] (Description of Material Selection for Electrostatic Chuck Module According to the Embodiment) Fig. 4 is a diagram showing a relationship between the thermal expansion coefficient of the material of the electrostatic chuck module according to the embodiment and temperature. Fig. 5 is a diagram showing a relationship between the difference in the thermal expansion coefficient of the material of the electrostatic chuck module according to the embodiment and the stress generated between the materials. Selection of the material of the electrostatic chuck module according to the embodiment will be described with reference to Figs. 4 and 5.

[0041] 4, it can be seen that the thermal expansion coefficient of tungsten is close to that of aluminum nitride (AlN) at temperatures from 300 K to 800 K, which are the operating temperatures of electrostatic chuck module 100. Tungsten is a metal with a thermal conductivity of 100 W / m K or more. Therefore, tungsten can be used for heat spreader plate 103, and aluminum nitride can be used for ceramic plate 104.

[0042] If the difference between the thermal expansion coefficient of the ceramic plate 104 and the thermal expansion coefficient of the heat spreader 103 becomes large, the ceramic plate 104 will be damaged. Therefore, we will consider how much difference in the thermal expansion coefficient is acceptable. Aluminum oxide, which is the material of the ceramic plate, generally tends to break under a stress of 300 MPa or more. As shown in Figure 5, if the difference between the thermal expansion coefficient of the ceramic plate 104 and the thermal expansion coefficient of the heat spreader 103 is ±2×10 -6 / K, a stress of 300 MPa or more will be generated. Therefore, the difference between the thermal expansion coefficient of the heat spreader 103 and the thermal expansion coefficient of the ceramic plate 104 is ±2×10 -6 It is preferable to select a material that is within 0.15 K.

[0043] (Explanation of the thickness of the protruding portion of the electrostatic chuck module according to the embodiment) Fig. 6 is a diagram showing the thickness of the protruding portion of the electrostatic chuck module according to the embodiment and the structure of the simulation. Fig. 7 is a diagram showing the simulation result of the relationship between the thickness of the protruding portion of the electrostatic chuck module according to the embodiment and the temperature variation of the heat equalizing plate and the surface distortion. The thickness of the protruding portion of the electrostatic chuck module according to the embodiment will be described with reference to Figs. 6 and 7.

[0044] 6, the thickness of the protrusion represents the width in the circumferential direction in the cross-sectional view of the electrostatic chuck module. Assuming that the thickness of the protrusion is the width of the joint between the protrusion 101b and the heat equalizer 103, a simulation of the temperature variation and surface distortion of the heat equalizer was performed with the upper surface at 450°C or higher and the lower surface at 70°C.

[0045] The results are shown in Figure 7. The higher the temperature, the higher the temperature variation of the heat soaking plate. It is better to have a smaller temperature variation of the heat soaking plate. If the allowable temperature variation is set to ±2% from 450°C, the difference between the maximum and minimum temperatures is within 18°C. Therefore, it is better to keep the thickness of the convex part to 5 mm or less.

[0046] On the other hand, it is better if the surface distortion is small. As for the distortion amount of the wafer substrate and the force required for it, an electrostatic adsorption force of 4.0 N is required for every 100 μm of distortion amount of the wafer substrate. Since the electrostatic adsorption force of the ceramic plate 104 is about 14 N at 2.5 kV, the ceramic plate 104 can follow a wafer substrate distortion of about 300 μm. Therefore, from FIG. 7, the thickness of the convex portion to obtain the amount of wafer distortion that can be adsorbed is 2 mm or more and 6 mm or less.

[0047] Considering the temperature variation of the hot plate and the surface distortion, it is preferable that the thickness of the protrusions is set to 2 mm or more and 5 mm or less.

[0048] (Description of Fixation of Electrostatic Chuck Module with Fastening Member According to an Embodiment) Fig. 8 is a schematic diagram showing an electrostatic chuck module according to an embodiment fixed with a fastening member. Fig. 9 is a diagram showing surface distortion when the electrostatic chuck module according to the embodiment is not fixed with a fastening member and when it is fixed with a fastening member. Fixing of the electrostatic chuck module according to the embodiment with a fastening member will be described with reference to Figs. 8 and 9.

[0049] As shown in Fig. 8, the base 101 and the heat equalizing plate 103 are fixed together by, for example, fastening members 801a and 801b. In this manner, the surface distortion of the ceramic plate 104 can be further suppressed. In Fig. 8, the base 101 is fixed together with the fastening members from the side of the base 101, but the heat equalizing plate 103 may also be fixed together with the fastening members from the side of the heat equalizing plate 103. The fastening members are, for example, screws or rivets. The fastening members may be fixed more firmly by using disc springs or members having spring force. The member having spring force is, for example, a spring.

[0050] As shown in Figure 9, it can be seen that the surface distortion is smaller when fixed with fastening members than when not fixed with fastening members, regardless of the thickness of the protruding portion of the base 101. This makes it possible to suppress upward convex deformation caused by thermal expansion of the heat equalizing plate at high temperatures and improve the amount of deformation of the wafer substrate during electrostatic adsorption. In addition, it is possible to reduce the load on the joint caused by deformation caused by thermal expansion of the materials from the insulating material 102 to the ceramic plate 104, thereby improving the joint reliability at high temperatures.

[0051] The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0052] 100 electrostatic chuck module, 101 base, 101a recess, 101b protrusion, 101c labyrinth structure, 101d flow path, 102 heat insulating material, 103 heat equalizing plate, 104 ceramic plate, 105 inorganic adhesive, 106 resistance heating element, 107 electrode, 108 insulator, 801a fastening member, 801b fastening member

Claims

1. A base having a flow path through which a coolant can flow in a lower portion thereof, and having a recess in an upper portion thereof and a protrusion disposed on an outer periphery of the recess; A heat insulating material disposed in the recess of the base; A resistive heating element disposed on or within the thermal insulation material; A heat spreader plate disposed on the heat insulating material and the resistance heating element; a ceramic plate disposed on the heat equalizing plate and having an electrode for attracting the workpiece by static electricity; The protruding portion of the base is joined to the heat equalizing plate.

2. The resistive heating elements are multiple, The plurality of resistive heating elements are arranged in a concentric circle shape, The electrostatic chuck module of claim 1 , wherein the plurality of resistive heating elements can be independently heated to a temperature of 300° C. or higher.

3. The difference between the thermal expansion coefficient of the ceramic plate and the thermal expansion coefficient of the electrostatic chuck of the heat equalizing plate at the operating temperature is ±2×10 －６ 2. The electrostatic chuck module of claim 1, wherein the axial length of the electrostatic chuck module is within 1 / K.

4. The electrostatic chuck module according to claim 1 , wherein the thickness of the protruding portion of the base is not less than 2 mm and not more than 5 mm.

5. The electrostatic chuck module according to claim 1 , wherein the heat spreader plate is directly or indirectly bonded to the heat insulating material using an inorganic adhesive.

6. 6. The electrostatic chuck module according to claim 5, wherein an insulator is interposed between the heat spreader plate and the heat insulating material, and the resistance heating element is not in direct contact with the heat spreader plate.

7. The electrostatic chuck module according to claim 1 , wherein a labyrinth structure is disposed under the protruding portion of the base.

8. The electrostatic chuck module according to claim 1 , wherein the heat spreader plate is fixed to the base by a fastening member.

9. 9. The electrostatic chuck module according to claim 8, wherein a disc spring or a member having a spring force is used to fix the fastening member.

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