Electrostatic chuck and substrate fixing device

Abstract

The present disclosure provides an electrostatic chuck and a substrate fixing device. The electrostatic chuck is configured to adsorb and hold an object thereon. The electrostatic chuck includes: a base body on which the object is mounted; an electrostatic electrode provided in the base body; a plurality of heating elements provided in the base body; and a plurality of current control elements provided in the base body, and each of the plurality of current control elements is connected in series with a corresponding one of the heating elements; each operation of the current control element is controlled according to light radiated from the outside of the base body toward a corresponding one of the current control elements.

Description

Technical Field

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

[0002] In the background art, a film forming apparatus or a plasma etching apparatus for manufacturing semiconductor devices has a platform for precisely holding a wafer on the platform in a vacuum processing chamber. For example, a substrate fixing device as the platform has been proposed, which adsorbs and holds a wafer by an electrostatic chuck mounted on a bottom plate.

[0003] As an example of a substrate fixing device, there is a substrate fixing device having a structure provided with a heating element for adjusting the temperature of a wafer. For example, regarding such a substrate fixing device, a method has been proposed in which a resistor is disposed in the electrostatic chuck as a heating element, and electric energy is applied to the resistor to generate heat, or a method has been proposed in which light emitting diodes used as heating elements are arranged in a regular array having a fixed number of rows and a fixed number of columns, or arranged in relation to the diameters of concentric circles such that an outer concentric circle among the concentric circles has a larger number of light emitting diodes than an inner concentric circle (for example, see JP-A-2018-525813).

[0004] However, in order to independently control a plurality of heating elements in a substrate fixing device, a large number of wires for control need to be led out to the outside of the electrostatic chuck. In addition, the wires led out to the outside of the electrostatic chuck need to be led out to the outside through through-holes formed in the bottom plate. Therefore, as the number of wires increases, the number of through-holes also increases. That is, due to the increase in the number of wires, the area occupied by the through-holes in the bottom plate increases, and the degree of freedom in designing the bottom plate decreases. Summary of the Invention

[0005] The present disclosure provides an electrostatic chuck that can suppress a decrease in the degree of freedom in designing a bottom plate even when a plurality of heating elements are provided in the electrostatic chuck.

[0006] One embodiment provides an electrostatic chuck configured to adsorb and hold an object on the electrostatic chuck.

[0007] The electrostatic chuck includes:

[0008] a base body on which the object is mounted;

[0009] an electrostatic electrode provided in the base body;

[0010] a plurality of heating elements provided in the base body; and

[0011] A plurality of current control elements are provided in a substrate, and each of the plurality of current control elements is connected in series with a corresponding one of the heating elements.

[0012] Each operation of the current control element is controlled in accordance with light radiated from the outside of the substrate toward a corresponding one of the current control elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 FIG. is a schematic cross-sectional view showing a substrate fixing device according to a first embodiment in a simplified manner;

[0014] Figure 2 FIG. is a plan view showing a temperature controllable region defined in the substrate;

[0015] Figure 3 FIG. is a plan view schematically showing heating elements respectively arranged in the temperature controllable region;

[0016] Figure 4 FIG. is a diagram showing an electrical connection between a heating element and a current control element in a substrate fixing device according to the first embodiment;

[0017] Figure 5 FIG. is a partial cross-sectional view showing a mounting structure of a peripheral portion of the current control element;

[0018] Figure 6 FIG. Figure 5 is a partially enlarged cross-sectional view in which a peripheral portion of the current control element in FIG. is enlarged;

[0019] Figure 7 FIG. is a schematic cross-sectional view showing a substrate fixing device according to a comparative example in a simplified manner;

[0020] Figure 8 FIG. is a partially enlarged cross-sectional view in which a peripheral portion of the current control element in a substrate fixing device according to Modification 1 of the first embodiment is enlarged; and

[0021] Figure 9 FIG. is a schematic cross-sectional view showing a substrate fixing device according to Modification 2 of the first embodiment in a simplified manner. DETAILED DESCRIPTION

[0022] Embodiments of the present disclosure will be described below with reference to the drawings. In each drawing, the same constituent parts will be denoted by the same reference numerals accordingly and respectively, and repeated descriptions of these constituent parts may be omitted.

[0023] (First Embodiment)

[0024] Figure 1It is a schematic cross-sectional view showing a substrate fixing device according to a first embodiment in a simplified manner. Refer to Figure 1 , the substrate fixing device 1 has a bottom plate 10, an adhesive layer 20, an electrostatic chuck 30, and an optical fiber 80 as main components. The substrate fixing device 1 is a device that adsorbs and holds a substrate (such as a wafer) to be adsorbed by the electrostatic chuck 30 mounted on one surface of the bottom plate 10.

[0025] The bottom plate 10 is configured to mount the electrostatic chuck 30 thereon. For example, the thickness of the bottom plate 10 is about 20 mm to 40 mm. For example, the bottom plate 10 formed of aluminum can be used as an electrode for controlling plasma. By supplying predetermined high-frequency power to the bottom plate 10, the energy for causing ions in a plasma state to collide with the substrate adsorbed on the electrostatic chuck 30 can be controlled, thereby effectively etching the substrate.

[0026] A gas supply path may be provided in the bottom plate 10, and an inert gas for cooling the substrate adsorbed on the electrostatic chuck 30 is introduced into the gas supply path. For example, when an inert gas (such as He or Ar) is introduced into the gas supply path from the outside of the substrate fixing device 1 and the inert gas is supplied to the back surface of the substrate adsorbed on the electrostatic chuck 30, the substrate can be cooled.

[0027] A refrigerant flow path may be provided in the bottom plate 10. For example, the refrigerant flow path is a hole formed in a ring shape inside the bottom plate 10. For example, a refrigerant such as cooling water or a heat transfer fluid (Galden) is introduced into the refrigerant flow path from the outside of the substrate fixing device 1. When the refrigerant circulates in the refrigerant flow path to cool the bottom plate 10, the substrate adsorbed on the electrostatic chuck 30 can be cooled.

[0028] The electrostatic chuck 30 is configured to adsorb and hold a substrate to be adsorbed. For example, the planar shape of the electrostatic chuck 30 is circular. For example, the diameter of the substrate adsorbed by the electrostatic chuck 30 is 8 inches, 12 inches, or 18 inches.

[0029] Here, it is assumed that the plan view represents a view of the object observed from the normal direction of the upper surface 10a of the bottom plate 10, and the planar shape represents the shape of the object observed from the normal direction of the upper surface 10a of the bottom plate 10.

[0030] The electrostatic chuck 30 is provided on the upper surface 10a of the bottom plate 10 through the adhesive layer 20. For example, the adhesive layer 20 is a silicon-based adhesive. For example, the thickness of the adhesive layer 20 is about 0.1 mm to 2.0 mm. The adhesive layer 20 bonds the bottom plate 10 and the electrostatic chuck 30 to each other, and the adhesive layer 20 has the effect of reducing the stress caused by the difference in the thermal expansion coefficients between the electrostatic chuck 30 made of ceramic and the bottom plate 10 made of aluminum.

[0031] The electrostatic chuck 30 has a base 31, an electrostatic electrode 32, a plurality of heating elements 33, a plurality of current control elements 34, and wiring 36 as main constituent elements. The upper surface of the base 31 is a mounting surface 31a, on which an object to be adsorbed is mounted. For example, the electrostatic chuck 30 is a Johnsen-Rahbek type electrostatic chuck. However, the electrostatic chuck 30 may alternatively be a Coulomb force type electrostatic chuck.

[0032] The base 31 is a dielectric. Ceramics such as alumina (Al2O3) or aluminum nitride (AlN) can be used as the base 31. The base 31 may contain, for example, oxides of two or more elements selected from the group including silicon (Si), magnesium (Mg), calcium (Ca), aluminum (Al), and yttrium (Y) as additives. For example, the thickness of the base 31 is about 5 mm to 10 mm. For example, the relative dielectric constant (at 1 kHz) of the base 31 is about 9 to 10.

[0033] For example, the electrostatic electrode 32, which is a thin film electrode, is built into the base 31. When the electrostatic electrode 32 is connected to a power source provided outside the substrate fixing device 1 and a predetermined voltage is applied from the power source to the electrostatic electrode 32, an adsorption force is generated between the electrostatic electrode 32 and the wafer due to static electricity. Therefore, the wafer can be adsorbed and held on the mounting surface 31a of the base 31 of the electrostatic chuck 30. The higher the voltage applied to the electrostatic electrode 32, the stronger the adsorption holding force. The electrostatic electrode 32 can have a monopolar shape or a bipolar shape. For example, materials such as tungsten and molybdenum are used for the electrostatic electrode 32.

[0034] Figure 2 is a plan view showing a temperature controllable region defined in the base. As Figure 2 shown, in the plan view, a plurality of temperature controllable regions 31e, in which the temperature can be independently controlled, are defined in the base 31. In Figure 2 the example, thirty temperature controllable regions 31e are defined. However, the number of the temperature controllable regions 31e can alternatively be set in the range of about 100 to 200. In addition, each temperature controllable region 31e can have any planar shape. For example, the temperature controllable regions 31 do not necessarily have to be substantially divided into a concentric shape, but can be substantially divided into a grid shape.

[0035] Figure 3 is a plan view schematically showing heating elements respectively arranged in the temperature controllable regions. The heating element 33 is a heater built into the base 31, and when current flows into the heater, the heater generates heat to heat the mounting surface 31a of the base 31 to a predetermined temperature.

[0036] As Figure 3As shown, a heating element 33 is arranged in each temperature - controllable region 31e. The heating elements 33 arranged in the temperature - controllable regions 31e are isolated from each other. By changing the current value flowing into each heating element 33, the heat generated by the heating element 33 can be independently changed. In this way, a plurality of temperature - controllable regions 31e with independently controllable temperatures are defined in the base 31, and the heating elements 33 are respectively arranged in the temperature - controllable regions 31e. With this arrangement, the mounting surface 31a of the base 31 can be heated evenly.

[0037] For example, the heating element 33 can heat the temperature of the mounting surface 31a of the base 31 to about 50°C to 200°C. For example, materials such as tungsten (W), copper (Cu), nickel (Ni), constantan (Cu / Ni / Mn / Fe alloy), etc. can be used as the material of the heating element 33. For example, the thickness of each heating element 33 is about 20μm to 100μm. For example, the heating element 33 can be formed into a predetermined pattern such as a zigzag pattern.

[0038] Figure 4 FIG. is a diagram showing the electrical connection between the heating element and the current - control element in the substrate fixing device according to the first embodiment. As Figure 4 shown, the current - control element 34 is built into the base 31, and one heating element 33 is connected in series with one current - control element 34. Each light receiver of the current - control element 34 is exposed to the outside of the base 31 so that the light receiver of the current - control element 34 can receive light from the outside of the base 31. In Figure 4 FIG., L represents the light (such as the light of a laser or a light - emitting diode) radiated from the optical fiber 80 toward the light receiver of the current - control element 34.

[0039] The current - control element 34 is an element whose operation is controlled by the reception of light. When light is radiated from the outside of the base 31 onto the light receiver of the current - control element 34, the current - control element 34 is electrically turned on to allow a predetermined current to flow into the heating element 33 connected to the current - control element 34, so that the heating element 33 generates heat. For example, the current - control element 34 is a phototransistor. However, the current - control element 34 can alternatively be a photoresistor (CdS cell), a solar cell, etc. For example, the size of the current - control element 34 is about 3mm in length × 3mm in width × 1mm in height.

[0040] In Figure 4 the example shown, the current - control element 34 is a phototransistor. The current - control element 34 has a first terminal (emitter) electrically connected to one end of the heating element 33, and the other end of the heating element 33 is electrically connected to the ground GND. The current - control element 34 has a second terminal (collector) electrically connected to VDD (power supply). Preferably, a high - heat - resistance phototransistor is used as the current - control element 34.

[0041] The wire 61 connected to the ground GND is led out to the outside of the substrate fixing device 1. The wire 62 (VDD) connected to the power supply VDD is led out to the outside of the substrate fixing device 1. In addition, one optical fiber 80 is assigned to one current control element 34, and each optical fiber 80 is led out to the outside of the substrate fixing device 1.

[0042] The wire 61, the wire 62, and the optical fiber 80 are directly led out to the outside of the substrate fixing device 1. Alternatively, sockets may be provided on the bottom plate 10 so that the wire 61, the wire 62, and the optical fiber 80 can be connected to the outside of the substrate fixing device 1 through the sockets.

[0043] When light is radiated from the outside of the substrate fixing device 1 to each photoreceiver of the current control element 34 through the optical fiber 80, the current control element 34 is electrically turned on to allow current to flow into the heating element 33 connected to the current control element 34. In this way, the current control element 34 can be used as a switch to perform an on / off operation according to the light from the outside of the substrate fixing device 1. The heat generated by the heating element 33 can be changed by changing the conduction operation time (running time) of the current control element 34. In addition, the heat generated by the heating element 33 can be changed by changing the intensity of the light radiated to the current control element 34.

[0044] Although three series circuits composed of the heating element 33 and the current control element 34 are shown in Figure 4 , the number of series circuits composed of the heating element 33 and the current control element 34 can be set to be the same as the number of temperature controllable regions 31e. For example, when there are one hundred temperature controllable regions 31e, one hundred series circuits composed of the heating element 33 and the current control element 34 are provided.

[0045] Figure 5 is a partial cross-sectional view showing the mounting structure of the peripheral portion of the current control element. Figure 6 is Figure 5 a partially enlarged cross-sectional view in which the peripheral portion of the current control element in Figure 5 and Figure 6 is enlarged. Referring to

[0046] On the lower surface of the base 31, recesses 31x and 31z opening toward the adhesive layer 20 are formed.

[0047] A wiring 36 is built in a substrate 31. The wiring 36 includes a current control element mounting pad, a solder connection pad, a wiring pattern, and the like. The wiring 36 is formed as a layer. Predetermined portions of the wiring 36 positioned in different layers are connected to each other by via wirings 37. In addition, a predetermined portion of the wiring 36 is electrically connected to a predetermined portion of the heating element 33 by a via wiring 37. For example, tungsten (W), molybdenum (Mo), etc. can be used as the material of the wiring 36 and the via wiring 37.

[0048] The current control element mounting pad of the wiring 36 is exposed in the recess 31x. For example, a current control element 34 disposed in the recess 31x is mounted on the current control element mounting pad of the wiring 36 in a flip chip manner.

[0049] Through holes 10x for allowing an optical fiber 80 to pass through are formed in the bottom plate 10 and the adhesive layer 20 so as to communicate with the recess 31x. The optical receiver of the current control element 34 disposed in the recess 31x faces the adhesive layer 20 side, and an optical fiber 80 is disposed in the through hole 10x, and light can propagate through the optical fiber 80 to irradiate the optical receiver of the current control element 34. That is, the optical receiver of the current control element 34 is disposed at a position where the optical receiver of the current control element 34 can receive light emitted from the optical fiber 80. The optical fiber 80 can be fixed to the through hole 10x by an adhesive or the like, or can be fixed to the bottom plate 10 by a socket provided on the lower surface of the bottom plate 10.

[0050] The solder connection pads of the wiring 36 are respectively exposed in the recesses 31z. Through holes 10y for allowing wires to pass through are formed in the bottom plate 10 and the adhesive layer 20 so as to communicate with the recesses 31z respectively. A GND wire 61 disposed in one through hole 10y is electrically connected to one solder connection pad by solder 50. A power supply VDD wire 62 disposed in the other through hole 10y is electrically connected to the other solder connection pad by another solder 50.

[0051] For example, each of the wires 61 and 62 has a structure in which a conductor is coated with an insulator. The conductors of the wires 61 and 62 are respectively electrically connected to the solder connection pads by solder 50. In order to enhance the insulation between the wires 61 and 62 and the bottom plate 10, it is preferable that insulating layers 15 are respectively provided on the inner walls of the through holes 10y. For example, resin, ceramic, etc. can be used as the insulating layer 15.

[0052] Relatively large currents flow into the GND wire 61 and the power supply VDD wire 62. Accordingly, the diameter of the via hole 10y in which each of the wires 61 and 62 is disposed is larger than the diameter of the via hole 10x in which the optical fiber 80 is disposed. Further, the diameter of each of the wires 61 and 62 is larger than the diameter of the optical fiber 80. For example, the diameter of the via hole 10y in which the wires 61 and 62 are disposed is φ5 mm, and for example, the diameter of the via hole 10x in which the optical fiber 80 is disposed is 0.5 mm. The diameters of the wires 61 and 62 are, for example, φ4 mm, and the diameter of the optical fiber 80 is, for example, φ0.2 mm.

[0053] A method for manufacturing such a substrate fixing device 1 will be described. To manufacture the substrate fixing device 1, first, an electrostatic chuck 30 in which an electrostatic electrode 32, a heating element 33, and a wiring 36 are built in a base body 31 is manufactured by a known manufacturing method, the known manufacturing method including steps of processing via holes in a green sheet, filling the via holes with a conductive paste, forming a pattern to serve as the electrostatic electrode, forming a pattern to serve as the heating element, forming a pattern to serve as the wiring, laminating and baking another green sheet, flattening the surface, and the like.

[0054] Then, a required number of recesses 31x are formed to expose the current control element mounting pads of the wiring 36, the recesses 31x being recessed from the lower surface of the base body 31 toward the mounting surface 31a of the base body 31. Further, a required number of recesses 31z are formed to expose the solder connection pads of the wiring 36, the recesses 31z being recessed from the lower surface of the base body 31 toward the mounting surface 31a of the base body 31. For example, the recesses 31x and 31z are formed by laminating a perforated green sheet on the lowermost surface.

[0055] Next, for example, the current control element 34 is mounted on the current control element mounting pads of the wiring 36 exposed within the recess 31x by a flip chip mounting method.

[0056] Next, the conductor portions of the wires are connected to the solder connection pads within the recess 31z by solder 50. Then, an uncured adhesive layer 20 is formed on the lower surface of the electrostatic chuck 30 except for the portions where the recesses 31x and 31z are formed. Further, a bottom plate 10 is prepared in which a through hole 10x through which the optical fiber 80 passes, through holes 10y through which the wires 61 and 62 pass, a refrigerant flow path, a gas supply path, and the like are formed. Then, the wires are passed through the through holes 10y. Then, the bottom plate 10 is connected to the lower surface of the electrostatic chuck 30 by the adhesive layer 20, and the adhesive layer 20 is cured. The optical fiber 80 is passed through the through hole 10x. Through the above steps, the Figure 1 illustrated substrate fixing device 1 is completed.

[0057] The effects obtained by the electrostatic chuck 30 constituting the substrate fixing device 1 will be described using a comparative example.

[0058] Figure 7 FIG. is a schematic cross-sectional view showing the substrate fixing device according to the comparative example in a simplified manner. Refer to Figure 7 , the substrate fixing device 1X is different from the substrate fixing device 1 (see Figure 1 etc.) in that the electrostatic chuck 30X is used instead of the electrostatic chuck 30.

[0059] The electrostatic chuck 30X has a base 31, an electrostatic electrode 32, a heating element 33, and wirings 36 as main constituent elements. A current control element 34 is not built in the electrostatic chuck 30X. In a plan view, a plurality of temperature controllable regions 31e whose temperatures can be independently controlled are defined in the base 31 in a similar or identical manner to Figure 2 . Further, one heating element 33 is arranged in each temperature controllable region 31e in a similar or identical manner to Figure 3 . The heating elements 33 arranged in the temperature controllable regions 31e are insulated from each other. By changing the current value flowing into each heating element 33, the heat generated by the heating element 33 can be independently changed.

[0060] One end of the heating element 33 is connected to each other through the wiring 36, and then one end of the heating element 33 is connected to the input / output IN1 wire 65(IN1) via the wiring 36. The wire 65(IN1) is led out to the outside of the substrate fixing device 1X. The other end of the heating element 33 is respectively connected to the input / output IN2 wire 66(IN2). The wire 66(IN2) is led out to the outside of the substrate fixing device 1X. The total number of the wire 65 and the wire 66 is the number of the heating elements 33 plus 1. For example, when there are one hundred heating elements 33, the total number of the wire 65 and the wire 66 is one hundred and one.

[0061] For example, one of the wire 65 and each wire 66 is connected to GND, and the other of the wire 65 and the wire 66 is connected to a power supply. The heat generated by each heating element 33 can be changed by the voltage value applied between the opposite ends of the heating element by the wire 65(IN1) and the wire 66(IN2). As an alternative, a constant voltage (pulse voltage) can be provided between the opposite ends of each heating element via the wire 65 and the wire 66, so that the heat generated by the heating element 33 can be changed by changing the time for which the voltage is applied to the heating element 33.

[0062] Since a large current required for the heating element 33 to generate heat flows into the wires 65 and 66, the diameter of each through hole 10y in which the wires 65 and 66 are arranged is, for example, φ5 mm. In addition, the diameter of the wires 65 and 66 is, for example, φ4 mm. Therefore, as the total number of the wires 65 and 66 increases, the area occupied by the through holes 10y in the base plate 10 becomes so large that it cannot be ignored.

[0063] For example, assume that in the case of the structure of the substrate fixing device 1X of the comparative example shown in Figure 7 the number of temperature controllable regions 31e is 100. In this case, the number of electrical connection lines between the substrate fixing device and the outside is more than 100. That is, more than one hundred wires must be led out to the outside through the through holes 10x formed in the base plate 10. In this case, as described above, the area occupied by the through holes 10x in the base plate 10 becomes so large that it cannot be ignored, and the degree of freedom for designing the base plate 10 is significantly reduced.

[0064] In addition, in the case of the substrate fixing device 1, the same number of optical fibers 80 as the temperature control regions 31e is required. However, as described above, the diameter of each through hole 10y in which the wires 61 and 62 are arranged is about φ5 mm, while the diameter of each through hole 10x in which the optical fiber 80 is arranged is about φ0.5 mm, and the diameter of the through hole 10x is about one-tenth of the diameter of the through hole 10y.

[0065] Therefore, even when a large number of through holes 10x are provided in the base plate 10, the area occupied by the through holes 10x in the base plate 10 is significantly reduced compared with the case where the same number of through holes 10y are provided in the base plate 10. That is, even when a large number of through holes 10x are provided in the base plate 10, the electrostatic chuck 30 of the substrate fixing device 1 can suppress the reduction of the degree of freedom for designing the base plate 10.

[0066] In addition, as described above, the outside electrically connected to the substrate fixing device 1 is only composed of the power supply (VDD) and GND. Therefore, since the number of components required for connecting the substrate fixing device 1 to the outside is reduced, the cost can be reduced. In addition, due to a significant reduction in the number of solder joints, etc., the assembly difficulty can be greatly reduced, enabling an increase in production yield and reliability. Since the electrostatic chuck 30 is a consumable component, the cost reduction effect obtained by the increase in production yield is great.

[0067] In addition, the optical fiber 80 does not need to be electrically insulated from the base plate 10. Therefore, insulating materials, etc. are not required in each through hole 10x, which also reduces the cost.

[0068] (Modification Example 1 of the First Embodiment)

[0069] An example in which the position of the front end of each optical fiber is retracted downward is shown in Modification 1 of the first embodiment. In Modification 1 of the first embodiment, the description of the components having the same reference numerals as those in the above-described embodiment may be omitted.

[0070] Figure 8 is a partially enlarged cross-sectional view in which the peripheral portion of the current control element in the substrate fixing device according to Modification 1 of the first embodiment is enlarged.

[0071] In Figure 8 in a manner similar to or the same as that in Figure 6 the photoreceiver of the current control element 34 disposed in the recess 31x faces the adhesive layer 20 side so as to receive the light radiated via the optical fiber 80.

[0072] In Figure 6 the front end of the optical fiber 80 is located in the through hole 10x formed in the adhesive layer 20. On the other hand, in Figure 8 the front end of the optical fiber 80 is located in the through hole 10x formed in the bottom plate 10 but does not enter the through hole 10x formed in the adhesive layer 20.

[0073] Due to the difference in the coefficient of thermal expansion between the bottom plate 10 and the base 31, the base 31 generally shifts horizontally with respect to the bottom plate 10 according to temperature conditions. In this case, the adhesive layer 20 also shifts. Therefore, when the front end of the optical fiber 80 enters the through hole 10x formed in the adhesive layer 20, the front end of the optical fiber 80 may be damaged (such as deterioration). As shown in Figure 8 the front end of the optical fiber 80 is located in the through hole 10x formed in the bottom plate 10 but does not enter the through hole 10x formed in the adhesive layer 20. Therefore, the front end of the optical fiber 80 can be prevented from being damaged (such as deterioration). The amount of shift of the base 31 with respect to the bottom plate 10 is larger toward the outer peripheral side of the base 31. Therefore, a particularly remarkable effect is obtained in those through holes 10x disposed on the outer peripheral side of the bottom plate 10.

[0074] (Modification 2 of the first embodiment)

[0075] The substrate fixing device 1B is shown by way of example in Modification 2 of the first embodiment. The substrate fixing device 1B is provided with such an electrostatic chuck: another heating element is built in a layer different from the layer of the heating element 33 in the base 31, and the another heating element generates heat due to the voltage applied thereto from the outside. In Modification 2 of the first embodiment, the description of the components having the same reference numerals as those in the foregoing embodiment may be omitted.

[0076] Figure 9It is a schematic cross-sectional view showing the substrate fixing device 1B according to the modification 2 of the first embodiment in a simplified manner. Referring to Figure 9 , the substrate fixing device 1B is different from the substrate fixing device 1 (see Figure 1 etc.) in that the electrostatic chuck 30B is used instead of the electrostatic chuck 30. In addition, the electrostatic chuck 30B is different from the electrostatic chuck 30 (see Figure 1 etc.) in that a heating element 40, a wire 68, and a wire 69 are added.

[0077] In the electrostatic chuck 30B, the heating element 40 whose temperature can be controlled independently of the heating element 33 is arranged in a layer different from the layer of the heating element 33. For example, the heating element 40 can be arranged between the electrostatic electrode 32 and the heating element 33 in the thickness direction. For example, the heating element 40 formed as a single resistor such as a spiral pattern is arranged to heat the entire mounting surface 31a of the base 31 on a plurality of temperature controllable regions 31e. For example, the material of the heating element 40 is similar to or the same as the material of the heating element 33.

[0078] One end of the heating element 40 is connected to the input / output IN1 wire 68. The wire 68 is led out to the outside of the substrate fixing device 1B. The other end of the heating element 40 is connected to the input / output IN2 wire 69. The wire 69 is led out to the outside of the substrate fixing device 1B. Therefore, there is one wire 68 and one wire 69.

[0079] For example, one of the wire 68 and the wire 69 is connected to the ground GND, and the other of the wire 68 and the wire 69 is connected to the power supply. The heat generated by the heating element 40 can be changed by the voltage value applied between the opposite ends of the heating element 40 by the wire 68 and the wire 69. As an option, a constant voltage (pulse voltage) can be provided between the opposite ends of the heating element 40 through the wire 68 and the wire 69, so that the heat generated by the heating element 40 can be changed by changing the time of applying the voltage to the heating element 40.

[0080] Therefore, the heating element 40 can be built into the base 31 separately from the heating element 33. For example, current is made to flow into the heating element 40 to heat the mounting surface 31a of the base 31, and only the insufficiently heated part of the mounting surface 31a is heated by the heating element 33. With this arrangement, the entire mounting surface 31a of the base 31 can be heated evenly.

[0081] In the above description, the heating element 40 is set as a single resistor. However, the heating element 40 can be set as a plurality of independent resistors in order to independently control the temperature of a plurality of regions.

[0082] For example, in addition to semiconductor wafers (such as silicon wafers), glass substrates and the like used in the process of manufacturing liquid crystal panels and the like can be examples of objects adsorbed by the substrate fixing device according to the present disclosure.

[0083] Although the preferred embodiments and the like have been described in detail, the present invention is not limited to the above embodiments and the like, and various modifications and substitutions can be made in the above embodiments and the like without departing from the scope of the claims.

[0084] This application claims the priority of Japanese Patent Application No. 2020-014639 filed on January 31, 2020, the entire content of which is incorporated herein by reference.

Claims

1. A substrate fixing device, comprising: A bottom plate having a plurality of through holes; An electrostatic chuck mounted on one surface of the bottom plate and configured to adsorb and hold an object on the electrostatic chuck, the electrostatic chuck including: A base body on which the object is mounted; Electrostatic electrodes provided in the base body; A plurality of heating elements provided in the base body; and A plurality of current control elements provided in the base body, and each of the plurality of current control elements is connected in series with a corresponding one of the heating elements; Wherein, each operation of the current control element is controlled according to light radiated from the outside of the base body toward a corresponding one of the current control elements; and a plurality of optical fibers, each of the plurality of optical fibers is configured to emit light toward a corresponding one of the current control elements, and each of the plurality of optical fibers is arranged in a corresponding one of the through holes, Wherein each of the through holes faces a corresponding one of the current control elements, The substrate fixing device further includes: An adhesive layer provided between the first surface of the base body and the bottom plate to fix the electrostatic chuck and the bottom plate to each other, Wherein the through holes are formed in the bottom plate and the adhesive layer so as to expose the first surface of the base body, and Each of the front ends of the optical fibers is positioned in a corresponding one of the through holes formed in the bottom plate.

2. The substrate fixing device according to claim 1, wherein: A first current control element among the current control elements is connected in series with a first heating element among the heating elements, and The operation of the first current control element is controlled according to light radiated toward the first current control element among the current control elements so as to allow current to flow into the first heating element.

3. The substrate fixing device according to claim 1 or 2, wherein: The base body is divided into a plurality of regions, The temperature of the regions is independently controlled, and Each of the heating elements is arranged in a corresponding one of the regions.

4. The substrate fixing device according to claim 1 or 2, wherein: Each of the current control elements is a phototransistor.

5. The substrate fixing device according to claim 1 or 2, the electrostatic chuck further includes: Another heating element provided in the base body, wherein, in the thickness direction of the electrostatic chuck, the position of the another heating element is different from the position of the heating element.

Images