Electrostatic chuck, substrate fixing device

Abstract

To provide an electrostatic chuck with further improved heat uniformity.SOLUTION: An electrostatic chuck has a substrate having a placing surface on which an object to be sucked is placed, an insulating layer formed on the back side of the substrate, which is located on the opposite side of the placing surface, a heating body embedded in the insulating layer, and a heat diffusion layer embedded in the substrate. The heat diffusion layer is formed from a material having a higher thermal conductivity than the substrate.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electrostatic chuck and a substrate fixing device. [Background technology]

[0002] 2. Description of the Related Art Conventionally, film formation apparatuses (eg, CVD apparatuses, PVD apparatuses, etc.) and plasma etching apparatuses used in manufacturing semiconductor devices such as ICs and LSIs have a stage for precisely holding a wafer within a vacuum processing chamber.

[0003] As such a stage, for example, a substrate fixing device has been proposed that attracts and holds a wafer, which is an object to be attracted, by an electrostatic chuck mounted on a base plate. The electrostatic chuck includes, for example, a heating element and a metal layer that uniformly distributes heat from the heating element. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-88304 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in recent years, there has been a demand for electrostatic chucks with improved thermal uniformity, and it has been difficult for conventional structures to satisfy such demands.

[0006] The present invention has been made in consideration of the above-mentioned points, and an object of the present invention is to provide an electrostatic chuck with further improved thermal uniformity. [Means for solving the problem]

[0007] The electrostatic chuck includes a base having a mounting surface on which an object to be attracted is placed, an insulating layer formed on a back surface of the base opposite to the mounting surface, and a heating element built into the insulating layer. an electrode embedded in the substrate; and vertical wiring embedded in the substrate and electrically connected to the electrode;a thermal diffusion layer embedded in the base, the vertical wiring includes a pad, the thermal spreading layer is disposed on a layer on which the pad is disposed and spaced apart from the pad, The thermal diffusion layer is made of a material having a higher thermal conductivity than the base. Effect of the Invention

[0008] According to the disclosed technique, it is possible to provide an electrostatic chuck with improved thermal uniformity. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view illustrating a simplified example of a substrate fixing device according to a first embodiment. [Diagram 2] 5A to 5C are views (part 1) illustrating a manufacturing process of the substrate fixing device according to the first embodiment. [Diagram 3] 6A to 6C are views (part 2) illustrating the manufacturing process of the substrate fixing device according to the first embodiment. [Figure 4] 6A to 6C are views (part 3) illustrating the manufacturing process of the substrate fixing device according to the first embodiment. [Diagram 5] 1 is a cross-sectional view illustrating, in a simplified form, a substrate fixing device according to a first modified example of the first embodiment. [Figure 6] FIG. 13 is a diagram showing a simulation result. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and duplicated explanations may be omitted.

[0011] [Structure of the substrate fixing device] Fig. 1 is a cross-sectional view illustrating a substrate fixing device according to a first embodiment in a simplified manner. Referring to Fig. 1, the substrate fixing device 1 has a base plate 10, an adhesive layer 20, and an electrostatic chuck 30 as main components.

[0012] The base plate 10 is a member for mounting the electrostatic chuck 30. The thickness of the base plate 10 can be, for example, about 20 to 50 mm. The base plate 10 is made of, for example, aluminum, and can also be used as an electrode for controlling plasma. By supplying a predetermined high-frequency power to the base plate 10, the energy for causing ions in a generated plasma state to collide with the wafer attracted to the electrostatic chuck 30 can be controlled, and the etching process can be performed effectively.

[0013] A water channel 15 is provided inside the base plate 10. The water channel 15 has a cooling water inlet 15a at one end and a cooling water outlet 15b at the other end. The water channel 15 is connected to a cooling water control device (not shown) provided outside the substrate fixing device 1. The cooling water control device (not shown) introduces cooling water from the cooling water inlet 15a to the water channel 15 and discharges the cooling water from the cooling water outlet 15b. The wafer adsorbed on the electrostatic chuck 30 can be cooled by circulating the cooling water through the water channel 15 to cool the base plate 10. In addition to the water channel 15, the base plate 10 may be provided with a gas channel for introducing an inert gas to cool the wafer adsorbed on the electrostatic chuck 30.

[0014] The electrostatic chuck 30 is a part that attracts and holds a wafer, which is an object to be attracted. The planar shape of the electrostatic chuck 30 may be, for example, circular. The diameter of the wafer, which is an object to be attracted to the electrostatic chuck 30, may be, for example, about 8, 12, or 18 inches.

[0015] The electrostatic chuck 30 is mounted on one surface of the base plate 10 via an adhesive layer 20. For example, a silicone adhesive can be used as the adhesive layer 20. The thickness of the adhesive layer 20 can be, for example, about 2 mm. The thermal conductivity of the adhesive layer 20 is preferably 2 W / mK or more. The adhesive layer 20 may have a laminated structure in which a plurality of adhesive layers are laminated. For example, by making the adhesive layer 20 into a two-layer structure combining an adhesive with high thermal conductivity and an adhesive with low elasticity, it is possible to obtain an effect of reducing stress caused by the difference in thermal expansion with the aluminum base plate.

[0016] The electrostatic chuck 30 includes a base 31, an electrostatic electrode 32, a thermal diffusion layer 33, an insulating layer 34, and a heating element 35. The electrostatic chuck 30 is, for example, a Johnsen-Rahbek type electrostatic chuck. However, the electrostatic chuck 30 may be a Coulomb force type electrostatic chuck.

[0017] The base 31 is a dielectric material and has a mounting surface 31a on which an object to be attracted is placed. The base 31 may be made of ceramics such as aluminum oxide (Al2O3) or aluminum nitride (AlN). The thickness T of the base 31 may be, for example, about 4 to 10 mm, and the relative dielectric constant (1 kHz) of the base 31 may be, for example, about 9 to 10.

[0018] The electrostatic electrode 32 is a thin-film electrode and is built into the base 31. The electrostatic electrode 32 is electrically connected to the vertical wiring built into the base 31. The vertical wiring includes a plurality of pairs of pads 36 and vias 37 that are alternately stacked. The pads 36 of the lowest layer are exposed in a recess 31x that opens on the back side of the base 31. The pads 36 of the lowest layer are connected to a power source provided outside the substrate fixing device 1, and when a predetermined voltage is applied from the power source, an electrostatic adsorption force is generated between the pads 36 and the wafer. This allows the electrostatic chuck 30 to adsorb and hold the wafer on the mounting surface 31a of the base 31. The adsorption and holding force becomes stronger as the voltage applied to the electrostatic electrode 32 becomes higher. The electrostatic electrode 32 may be unipolar or bipolar. The electrostatic electrode 32, the pads 36, and the vias 37 may be made of, for example, tungsten, molybdenum, or the like.

[0019] The thermal diffusion layer 33 is built into the base 31. The thermal diffusion layer 33 is a layer that uniformly diffuses the heat generated by the heating element 35, and is made of a material having a higher thermal conductivity than the base 31. The thermal conductivity of the thermal diffusion layer 33 is preferably 400 W / m·k or more. Examples of materials that can achieve such a thermal conductivity include metals such as copper (Cu), copper alloys, silver (Ag), and silver alloys, and carbon nanotubes. The thickness of the thermal diffusion layer 33 can be, for example, about 5 μm to 20 μm.

[0020] Providing at least one thermal diffusion layer 33 within the base 31 provides the effect of uniformly diffusing the heat generated by the heating element 35 throughout the base 31. Stacking a plurality of thermal diffusion layers 33 in the thickness direction of the base 31 further enhances the effect of uniformly diffusing the heat generated by the heating element 35 throughout the base 31. From the viewpoint of improving the heat diffusion effect, it is preferable to arrange the thermal diffusion layers 33 throughout the entire base 31 in the horizontal direction (the direction parallel to the mounting surface 31a).

[0021] In the first embodiment, as an example, the thermal diffusion layers 33 are arranged in all layers where the pads 36 are arranged. In the example of Fig. 1, seven thermal diffusion layers 33 are stacked at a predetermined interval. The interval between adjacent thermal diffusion layers 33 in the vertical direction is, for example, 0.45 mm. The thermal diffusion layers 33 in each layer are arranged apart from the pads 36 so as not to be electrically connected to the pads 36. If the planar shape of the pads 36 is circular, for example, a circular opening larger in diameter than the pads 36 is formed in the thermal diffusion layers 33, and the pads 36 are located within the opening.

[0022] In the first embodiment, as an example, the thermal diffusion layer 33 is disposed over the entire horizontal area of ​​the base 31 except for the pad arrangement area, and the entire outer circumferential surface of the thermal diffusion layer 33 is exposed to the outer circumferential surface of the base 31. That is, the thermal diffusion layer 33 is formed up to the outermost periphery of the base 31. Here, the pad arrangement area refers to an area extending from the outer edge of the pad 36 to a range of 100 μm outward.

[0023] In addition, in conventional electrostatic chucks, a metal layer or the like functioning as a thermal diffusion layer is fixed to a base body via an adhesive layer, or the metal layer is patterned into a predetermined shape, and therefore sufficient thermal uniformity cannot be achieved.

[0024] The insulating layer 34 is formed directly on the back surface of the base 31 (the surface opposite to the mounting surface 31a). The insulating layer 34 is a layer that insulates the base 31 from the heating element 35. For example, an epoxy resin or a bismaleimide triazine resin having high thermal conductivity and high heat resistance can be used as the insulating layer 34. The thermal conductivity of the insulating layer 34 is preferably 3 W / mK or more. The thermal conductivity of the insulating layer 34 can be improved by including a filler such as alumina or aluminum nitride in the insulating layer 34. The glass transition temperature (Tg) of the insulating layer 34 is preferably 250° C. or more. The thickness of the insulating layer 34 is preferably about 100 to 150 μm, and the thickness variation of the insulating layer 34 is preferably ±10% or less.

[0025] The heating element 35 is built in the insulating layer 34. The heating element 35 is covered with the insulating layer 34 and protected from the outside. The heating element 35 generates heat by applying a voltage from the outside of the substrate fixing device 1, and heats the mounting surface 31a of the base 31 to a predetermined temperature. The heating element 35 can heat the mounting surface 31a of the base 31 to, for example, about 250°C to 300°C. The heating element 35 can be made of, for example, copper (Cu), tungsten (W), nickel (Ni), constantan (alloy of Cu / Ni / Mn / Fe), etc. The thickness of the heating element 35 can be, for example, about 20 to 100 μm. The heating element 35 can be, for example, in a concentric pattern.

[0026] In order to improve the adhesion between the heating element 35 and the insulating layer 34 at high temperatures, it is preferable that at least one surface (either the upper or lower surface or both) of the heating element 35 is roughened. Of course, both the upper and lower surfaces of the heating element 35 may be roughened. In this case, different roughening methods may be used for the upper and lower surfaces of the heating element 35. The roughening method is not particularly limited, but examples thereof include an etching method, a method using a coupling agent-based surface modification technique, and a method using dot processing with a UV-YAG laser having a wavelength of 355 nm or less.

[0027] [Manufacturing method of substrate fixing device] 2 to 4 are diagrams illustrating the manufacturing process of the substrate fixing device according to the first embodiment. The manufacturing process of the substrate fixing device 1 will be described with reference to Fig. 2 to Fig. 4, focusing on the process of forming an electrostatic chuck. Note that Fig. 2(a) to Fig. 4(a) are drawn upside down compared to Fig. 1.

[0028] First, in the step shown in FIG. 2(a), a green sheet 311 is prepared. For example, when the ceramic constituting the base 31 is aluminum oxide, the material constituting the green sheet 311 contains aluminum oxide particles. The material constituting the green sheet 311 may contain a binder, a solvent, and the like. The thickness of the green sheet 311 is, for example, 0.58 to 0.62 mm (about 0.45 mm after firing). Next, a metal paste 321 is printed in a predetermined pattern on one side of the green sheet 311. The metal paste 321 is a material that becomes the electrostatic electrode 32 by firing. The metal paste 321 is, for example, a tungsten paste or a molybdenum paste.

[0029] 2(b), a green sheet 312 covering the metal paste 321 is laminated on one side of the green sheet 311. The size and material of the green sheet 312 are the same as those of the green sheet 311. Next, vias are formed in the green sheet 312, and the vias are filled with a metal paste 371. The metal paste 371 is a material that becomes the vias 37 when fired. The metal paste 371 is, for example, a tungsten paste or a molybdenum paste.

[0030] 2(c), metal pastes 331 and 361 are printed in a predetermined pattern on one surface of the green sheet 312. The metal paste 331 is a material that will become the thermal diffusion layer 33 when fired. The metal paste 361 is a material that will become the pad 36 when fired. The metal pastes 331 and 361 are, for example, tungsten paste or molybdenum paste. The metal pastes 331 and 361 may be different materials.

[0031] Next, in the step shown in FIG. 2(d), the steps shown in FIG. 2(b) and FIG. 2(c) are repeated a required number of times, and then the required number of green sheets are laminated. For example, when the thickness of each green sheet is 0.58 to 0.62 mm, one layer of metal paste 331 that becomes the thermal diffusion layer 33 can be formed for every 0.58 to 0.62 mm thick. Next, after performing surface polishing as necessary, each green sheet is integrated by firing to form the base 31. Furthermore, the electrostatic electrode 32, the thermal diffusion layer 33, the pad 36, and the via 37 are formed from each metal paste by firing. After firing, the recess 31x is formed. The recess 31x can be formed by, for example, blasting or drilling. Note that, if there are other grooves or holes such as gas inlet portions, they are processed in the same manner.

[0032] Next, in the step shown in FIG. 3(a), an insulating resin film 341 is placed directly on the surface of the base 31 opposite the mounting surface 31a (the upper surface in FIG. 3(a)). The insulating resin film 341 is preferably laminated in a vacuum, since this can suppress the inclusion of voids. The insulating resin film 341 is not cured, but is left in a semi-cured state (B-stage). The adhesive force of the insulating resin film 341 in the semi-cured state allows the insulating resin film 341 to be temporarily fixed onto the base 31.

[0033] For example, epoxy resin or bismaleimide triazine resin having high thermal conductivity and high heat resistance can be used as the insulating resin film 341. The thermal conductivity of the insulating resin film 341 is preferably 3 W / mK or more. The thermal conductivity of the insulating resin film 341 can be improved by adding a filler such as alumina or aluminum nitride to the insulating resin film 341. The glass transition temperature of the insulating resin film 341 is preferably 250° C. or more. From the viewpoint of improving the thermal conduction performance (increasing the thermal conduction speed), the thickness of the insulating resin film 341 is preferably 60 μm or less, and the thickness variation of the insulating resin film 341 is preferably ±10% or less.

[0034] Next, in the step shown in FIG. 3(b), a metal foil is placed on the insulating resin film 341, and the metal foil is patterned to form the heating element 35. The heating element 35 can be formed, for example, in a concentric pattern. Specifically, for example, a resist is formed on the entire surface of the metal foil, and the resist is exposed and developed to form a resist pattern that covers only the portion to be left as the heating element 35. Next, the metal foil in the portion not covered by the resist pattern is removed by etching. For example, when the material of the metal foil is copper, a cupric chloride etching solution, a ferric chloride etching solution, or the like can be used as an etching solution for removing the metal foil.

[0035] Thereafter, the resist pattern is removed with a remover to form the heating element 35 at a predetermined position on the insulating resin film 341 (photolithography method). By forming the heating element 35 by photolithography, it is possible to reduce the dimensional variation in the width direction of the heating element 35, and the heat generation distribution can be improved. The cross-sectional shape of the heating element 35 formed by etching can be, for example, approximately trapezoidal. In this case, the difference in wiring width between the surface in contact with the insulating resin film 341 and the opposite surface can be, for example, about 10 to 50 μm. By forming the cross-sectional shape of the heating element 35 into a simple approximately trapezoidal shape, the heat generation distribution can be improved.

[0036] 3(c), an insulating resin film 342 that covers the heating element 35 is disposed on the insulating resin film 341. When the insulating resin film 342 is laminated in a vacuum, it is preferable in that the inclusion of voids can be suppressed. The material of the insulating resin film 342 can be the same as that of the insulating resin film 341, for example. However, the thickness of the insulating resin film 342 can be appropriately determined within a range that can cover the heating element 35, and does not necessarily have to be the same thickness as the insulating resin film 341.

[0037] Next, in the step shown in FIG. 4(a), the insulating resin films 341 and 342 are pressed against the base 31 side, while being heated to a curing temperature or higher to be cured. As a result, the insulating resin films 341 and 342 are integrated to become the insulating layer 34, and the insulating layer 34 is directly bonded to the thermal diffusion layer 33. The periphery of the heating element 35 is covered with the insulating layer 34. Next, a through hole is formed in the insulating layer 34, and the insulating layer 34 is connected to the recess 31x. In addition, in consideration of the stress when the temperature is returned to normal, the heating temperature of the insulating resin films 341 and 342 is preferably 200° C. or less. In this manner, the electrostatic chuck 30 is completed.

[0038] Incidentally, by heating and curing the insulating resin films 341 and 342 while pressing them against the base 31, it is possible to reduce and flatten the unevenness of the upper surface of the insulating layer 34 (the surface not in contact with the electrostatic chuck 30) caused by the presence or absence of the heating element 35. It is preferable that the unevenness of the upper surface of the insulating layer 34 is 7 μm or less. By keeping the unevenness of the upper surface of the insulating layer 34 to 7 μm or less, it is possible to prevent air bubbles from being trapped between the insulating layer 34 and the adhesive layer 20 in the next process. In other words, it is possible to prevent the adhesion between the insulating layer 34 and the adhesive layer 20 from decreasing.

[0039] 4(b), a base plate 10 having the water channels 15 and the like formed thereon is prepared, and an adhesive layer 20 (uncured) is formed on the base plate 10. Then, the electrostatic chuck 30 shown in FIG. 4(a) is turned upside down and placed on the base plate 10 with the adhesive layer 20 interposed therebetween, and the adhesive layer 20 is cured. This completes the substrate fixing device 1 in which the electrostatic chuck 30 is laminated on the base plate 10 with the adhesive layer 20 interposed therebetween.

[0040] In this manner, in the electrostatic chuck 30, since the thermal diffusion layer 33 is built into the base 31, the heat generated by the heating element 35 can be easily and uniformly transferred to the base 31. That is, in the electrostatic chuck 30, it is possible to further improve the thermal uniformity compared to a conventional structure in which a thermal diffusion layer is provided on the outside of the base.

[0041] Furthermore, by forming the thermal diffusion layer 33 over the entire horizontal surface of the base 31, the heat generated by the heating element 35 can be diffused evenly over the entire base 31. Furthermore, by making the thermal conductivity of the thermal diffusion layer 33 equal to or greater than 400 W / m·k, the heat can be diffused quickly in the horizontal direction of the base 31. The heat diffused evenly by the thermal diffusion layer 33 can heat the base 31 evenly.

[0042] In addition, if the heat diffusion distance from the heating element 35 to the mounting surface 31a is short, that is, the thinner the thickness T of the base 31, the more likely the influence of dimensional variations of the heating element 35 and the like will appear on the mounting surface 31a. In other words, if the thickness T of the base 31 is thicker, the heat diffusion distance from the heating element 35 to the mounting surface 31a will be extended, so that the temperature distribution on the mounting surface 31a will be blurred and the temperature distribution will be improved. By combining the provision of the thermal diffusion layer 33 inside the base 31 and increasing the thickness T of the base 31, a more effective improvement in the temperature distribution can be expected. Conventionally, the thickness T of the base 31 was often about 4.5 mm, but in order to improve the temperature distribution, it is preferable to set the thickness T of the base 31 to about 4.95 mm or more and 9 mm or less.

[0043] First Modification of the First Embodiment In the first modification of the first embodiment, an example in which the number of laminated thermal diffusion layers is further increased will be described. Note that in the first modification of the first embodiment, the description of the same components as those in the already described embodiment may be omitted.

[0044] 5 is a simplified cross-sectional view illustrating a substrate fixing device according to Modification 1 of the first embodiment. Referring to FIG. 5, the substrate fixing device 1A is different from the substrate fixing device 1 in that a thermal diffusion layer 33 is provided below the layer on which the pads 36 are formed.

[0045] That is, in the substrate fixing device 1A, the thermal diffusion layer 33 is disposed closer to the back surface of the base 31 than the pads 36 disposed closest to the back surface of the base 31. In order to provide the thermal diffusion layer 33 below the layer in which the pads 36 are formed, in the step of FIG. 2(d), one layer of metal paste 331 that becomes the thermal diffusion layer 33 may be formed for each stacking of the green sheets in which the recesses 31x are formed.

[0046] In this way, by effectively utilizing the area below the layer on which the pads 36 are formed and providing the thermal diffusion layer 33 in this area as well, the number of layers of the thermal diffusion layer 33 can be further increased, thereby making it possible to further improve thermal uniformity.

[0047] [simulation] For the four types of samples shown in Table 1 below, a simulation was performed on the temperature distribution (thermal uniformity) on the substrate mounting surface when the average temperature of the substrate mounting surface was controlled to 60 degrees. In Table 1, Ref is a sample with a substrate thickness of 4.5 mm and no thermal diffusion layer, which corresponds to a conventional electrostatic chuck. A is a sample with a substrate thickness of 6.8 mm and no thermal diffusion layer, which differs from Ref only in the substrate thickness. B is a sample with a substrate thickness of 6.8 mm and five thermal diffusion layers, which differs from A only in the presence or absence of a thermal diffusion layer. C is a sample with a substrate thickness of 6.8 mm and 14 thermal diffusion layers, which differs from B only in the number of thermal diffusion layers.

[0048] [Table 1] The simulation results are shown in Table 2. In Table 2, the average value is the average temperature of the substrate mounting surface, the range is the difference between the minimum temperature and the maximum temperature, and the Sigma is the standard deviation.

[0049] [Table 2] Fig. 6(a) shows the Range shown in Table 2 with the REF value as the reference (100%). Fig. 6(b) shows the Sigma shown in Table 2 with the REF value as the reference (100%).

[0050] In Fig. 6(a), comparing sample Ref with sample A, it can be seen that the Range value is reduced by about 33% when the substrate is made thicker, and in Fig. 6(b), comparing sample Ref with sample A, it can be seen that the Sigma value is reduced by just under 20% when the substrate is made thicker.

[0051] In addition, in Fig. 6(a), comparing Sample A with Sample B, it can be seen that the incorporation of a thermal diffusion layer in the base slightly improves the Range value, and in Fig. 6(b), comparing Sample A with Sample B, it can be seen that the incorporation of a thermal diffusion layer in the base slightly improves the Sigma value.

[0052] In addition, in Fig. 6(a), comparing Sample B with Sample C, it can be seen that increasing the number of thermal diffusion layers built into the base further improves the Range value. In addition, in Fig. 6(b), comparing Sample B with Sample C, it can be seen that increasing the number of thermal diffusion layers built into the base further improves the Sigma value.

[0053] In this way, it was confirmed that the temperature distribution variation on the mounting surface of the base was significantly improved by making the base thicker, and that the temperature distribution variation on the mounting surface of the base was further improved by incorporating a thermal diffusion layer in the base, improving thermal uniformity. It was also confirmed that the temperature distribution variation on the mounting surface of the base was further improved by increasing the number of thermal diffusion layers incorporated in the base, improving thermal uniformity.

[0054] Although preferred embodiments have been described above in detail, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims.

[0055] For example, examples of objects to be attracted by the substrate fixing device according to the present invention include glass substrates used in the manufacturing process of liquid crystal panels, etc., in addition to semiconductor wafers (silicon wafers, etc.). [Explanation of symbols]

[0056] 1, 1A board fixing device 10 Base plate 15 Waterways 15a Cooling water inlet 15b Cooling water outlet 20 Adhesive layer 30 Electrostatic Chuck 31 Base 31a Placement surface 31x recess 32 Electrostatic Electrode 33 Thermal diffusion layer 34 Insulating layer 35 Heating element 36 Pad 37 Via 321, 331, 361, 371 Metal Paste 341, 342 Insulating resin film

Claims

1. a base having a mounting surface on which an object to be attracted is placed; an insulating layer formed on a back surface of the base opposite to the mounting surface; A heating element embedded in the insulating layer; An electrode embedded in the substrate; a vertical wiring that is embedded in the substrate and is electrically connected to the electrode; a thermal diffusion layer embedded in the base, The vertical wiring includes a pad, the thermal diffusion layer is disposed on a layer on which the pads are disposed, the thermal diffusion layer being spaced apart from the pads; The thermal diffusion layer is formed from a material having a higher thermal conductivity than the base.

2. The electrostatic chuck according to claim 1 , wherein a plurality of said thermal spreading layers are stacked in a thickness direction of said base body.

3. The vertical wiring includes a plurality of pairs of alternatingly stacked pads and vias; 3. The electrostatic chuck according to claim 2, wherein the heat spreading layer is disposed in an entire layer in which the pad is disposed, and is spaced apart from the pad.

4. 4. The electrostatic chuck according to claim 3, wherein the heat spreading layer is disposed over the entire horizontal area of ​​the base except for a pad arrangement area.

5. 5. The electrostatic chuck according to claim 3, wherein the thermal diffusion layer is disposed closer to the rear surface of the base than the pad disposed closest to the rear surface of the base.

6. 6. The electrostatic chuck according to claim 1, wherein an entire outer circumferential surface of the thermal diffusion layer is exposed to an outer circumferential surface of the base.

7. A base plate; A substrate fixing device comprising: the electrostatic chuck according to claim 1 mounted on one surface of the base plate.

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