Substrate fixing device

Abstract

The present disclosure provides a substrate fixing device, comprising: an electrostatic chuck configured to attract and hold an object on the electrostatic chuck, the electrostatic chuck comprising a base, the object being mounted on the base, and an electrostatic electrode disposed in the base; and a base plate on which the electrostatic chuck is mounted, the base plate having a plurality of through holes, each of the plurality of through holes exposing a first surface of the base facing the base plate. Laser light is emitted from each of the through holes toward the base.

Description

Technical Field

[0001] The present disclosure relates to a substrate fixing device. Background Art

[0002] In the background art, film-forming equipment or plasma etching equipment used to manufacture semiconductor devices includes a platform for precisely holding a wafer on the platform within a vacuum processing chamber. For example, a substrate holding device has been proposed as such a platform. This substrate holding device uses an electrostatic chuck mounted on a base plate to attract and hold the wafer.

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

[0004] In order to independently control the temperature of multiple zones in a substrate fixture, a large number of control wires and other components must be routed outside the electrostatic chuck. Furthermore, these wires and other components must be routed to the outside of the electrostatic chuck via through-holes formed in the base plate. Therefore, as the number of wires and other components increases, the number of through-holes also increases. This increases the area occupied by the through-holes in the base plate, reducing the degree of freedom in base plate design. Summary of the Invention

[0005] The present disclosure provides a substrate holding device capable of suppressing a decrease in the degree of freedom for designing a base plate even when the temperatures of a plurality of regions of an electrostatic chuck are independently controlled.

[0006] A certain embodiment provides a substrate fixing device.

[0007] The substrate fixing device comprises:

[0008] an electrostatic chuck configured to adsorb and hold an object on the electrostatic chuck, and comprising a base on which the object is mounted and an electrostatic electrode provided in the base; and

[0009] The electrostatic chuck is mounted on the bottom plate, and the bottom plate has a plurality of through holes, each of the plurality of through holes exposing the first surface of the substrate facing the bottom plate.

[0010] Laser light is emitted from each of the through holes toward the base. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic cross-sectional view showing a substrate fixing device according to a first embodiment in a simplified manner;

[0012] Figure 2 is a plan view showing a temperature controllable area defined in a substrate;

[0013] Figure 3 is a plan view schematically showing an arrangement of optical fibers for heating temperature-controllable regions individually;

[0014] Figure 4 is a schematic diagram showing a laser irradiation device arranged outside a substrate fixing device;

[0015] Figure 5 is a schematic cross-sectional view showing a substrate fixing device according to a comparative example in a simplified manner;

[0016] Figure 6 is a partially enlarged cross-sectional view showing an enlarged portion of a peripheral portion of an optical fiber in a substrate fixing device according to Modification 1 of the first embodiment;

[0017] Figure 7 is a partially enlarged cross-sectional view enlarging a peripheral portion of an optical fiber in a substrate fixing device according to Modification 2 of the first embodiment; and

[0018] Figure 8 is a schematic cross-sectional view showing in a simplified manner a substrate fixing device according to Modification 3 of the first embodiment. DETAILED DESCRIPTION

[0019] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In each of the accompanying drawings, the same components will be respectively and respectively denoted by the same reference numerals, and repeated descriptions of these components may be omitted.

[0020] (First embodiment)

[0021] Figure 1 1 is a schematic cross-sectional view showing a substrate fixing device according to a first embodiment in a simplified manner. Figure 1The substrate fixing device 1 mainly includes a base plate 10, an adhesive layer 20, an electrostatic chuck 30, and an optical fiber 80. The substrate fixing device 1 is a device that attracts and holds a substrate (such as a wafer) as an attraction target by the electrostatic chuck 30 mounted on one surface of the base plate 10.

[0022] Base plate 10 is a member for mounting electrostatic chuck 30 thereon. For example, base plate 10 has a thickness of approximately 20 mm to 40 mm. Base plate 10, formed of aluminum, for example, can function as an electrode for controlling plasma. By supplying a predetermined high-frequency power to base plate 10, the energy used to cause ions in the plasma state to collide with the substrate held on electrostatic chuck 30 can be controlled, thereby efficiently etching the substrate.

[0023] A plurality of through holes 10x are formed in the base plate 10 and the adhesive layer 20, exposing the surface of the base 31 on the base plate 10 side. Optical fibers 80 for transmitting laser light are arranged in each of the through holes 10x. The optical fibers 80 can be fixed to the through holes 10x using an adhesive or the like, or can be fixed to the base plate 10 using a socket provided on the lower surface of the base plate 10.

[0024] A gas supply path may be provided in the base 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 outside the substrate fixing device 1 and supplied to the back side of the substrate adsorbed on the electrostatic chuck 30, the substrate can be cooled.

[0025] A refrigerant flow path may be provided in base plate 10. For example, the refrigerant flow path may be a hole formed in an annular shape within base plate 10. For example, a refrigerant, such as cooling water or a heat transfer fluid (Galden), may be introduced into the refrigerant flow path from outside substrate fixture 1. As the refrigerant circulates through the refrigerant flow path to cool base plate 10, the substrate attached to electrostatic chuck 30 can be cooled.

[0026] The electrostatic chuck 30 is a portion that attracts and holds a substrate to be attracted. For example, the planar shape of the electrostatic chuck 30 is circular. For example, the diameter of the substrate to be attracted by the electrostatic chuck 30 is 8 inches, 12 inches, or 18 inches.

[0027] It is assumed here that a plan view represents a view of an object viewed from the normal direction of the upper surface 10 a of the base plate 10 , and a planar shape represents a shape of the object viewed from the normal direction of the upper surface 10 a of the base plate 10 .

[0028] Electrostatic chuck 30 is disposed on upper surface 10a of base plate 10 via adhesive layer 20. Adhesive layer 20 is, for example, a silicone-based adhesive. Adhesive layer 20 has a thickness of, for example, approximately 0.1 mm to 2.0 mm. Adhesive layer 20 secures base plate 10 and electrostatic chuck 30 to each other and reduces stress caused by the difference in thermal expansion coefficient between electrostatic chuck 30, which is made of ceramic, and base plate 10, which is made of aluminum.

[0029] Electrostatic chuck 30 includes a base 31 and an electrostatic electrode 32 as its main components. The upper surface of base 31 is a mounting surface 31a, on which an object to be attracted is mounted. For example, electrostatic chuck 30 is a Johnson-Rahbek type electrostatic chuck. However, electrostatic chuck 30 may alternatively be a Coulomb force type electrostatic chuck.

[0030] The substrate 31 is a dielectric. For example, ceramics such as aluminum oxide (Al2O3) or aluminum nitride (AlN) can be used as the substrate 31. The substrate 31 may contain oxides of two or more elements selected from the group consisting of silicon (Si), magnesium (Mg), calcium (Ca), aluminum (Al), and yttrium (Y) as additives. For example, the thickness of the substrate 31 is approximately 5 mm to 10 mm. For example, the relative dielectric constant (at 1 kHz) of the substrate 31 is approximately 9 to 10.

[0031] For example, an electrostatic electrode 32, which serves as 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 fixture 1 and a predetermined voltage is applied to the electrostatic electrode 32 from the power source, static electricity generates an adsorption force between the electrostatic electrode 32 and the wafer. Consequently, 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 and holding force. The electrostatic electrode 32 can have a monopolar or bipolar shape. For example, tungsten, molybdenum, or the like is used as the material of the electrostatic electrode 32.

[0032] Figure 2 FIG is a plan view showing a temperature controllable area defined in a substrate. Figure 2 As shown in FIG. 3 , in a plan view, a plurality of temperature controllable regions 31 e whose temperatures can be independently controlled are defined in the base body 31 . Figure 2 In the example shown, thirty temperature-controllable regions 31e are defined. However, the number of temperature-controllable regions 31e may alternatively be set within a range of approximately 100 to 200. Furthermore, each temperature-controllable region 31e may have any planar shape. For example, the temperature-controllable regions 31e do not necessarily need to be divided into substantially concentric shapes, but may be divided into a substantially grid shape.

[0033] Figure 380 is a plan view schematically showing the arrangement of optical fibers for heating the temperature controllable regions. Laser light is propagated through the optical fibers 80. When the laser light propagated through the optical fibers 80 is radiated onto the substrate 31, the substrate 31 is heated.

[0034] like Figure 3 As shown, at least one optical fiber 80 is arranged in the base plate 10 at a position corresponding to each temperature-controllable region 31e. By varying the intensity of the laser light propagating through the optical fiber 80 arranged in each temperature-controllable region 31e, the amount of heat generated in each temperature-controllable region 31e can be independently varied. In this manner, independently temperature-controllable regions 31e, each of which can be controlled, are defined in the base plate 31, with an optical fiber 80 arranged in each temperature-controllable region 31e. This arrangement enables uniform heating of the mounting surface 31a of the substrate 31.

[0035] Figure 4 Schematic diagram showing a laser irradiation device arranged outside the substrate fixing device. Figure 4 As shown, the laser irradiation device 100 includes a laser light source 110, a reflector 120, an optical scanning unit 130, and a control circuit 140. For example, a YAG laser, a carbon dioxide gas laser, or the like can be used as the laser light source 110. When the substrate 31 contains aluminum oxide as a main component, the wavelength of the laser light emitted from the laser light source 110 is preferably in the infrared region, which is easily absorbed by aluminum oxide. The output of the laser light emitted from the laser light source 110 is preferably approximately several kilowatts to several tens of kilowatts.

[0036] As the optical scanning unit 130, for example, a galvano scanner in which two mirrors are controlled by a motor, an optical scanning unit formed by MEMS technology, a digital mirror device, etc. can be used. The laser light L emitted from the laser light source 110 based on the instruction of the control circuit 140 changes the optical path of the laser light L through the mirror 120 and then enters the optical scanning unit 130. The laser light L entering the optical scanning unit 130 is scanned by the optical scanning unit 130 based on the instruction of the control circuit 140 so as to enter a predetermined one of the optical fibers 80 and reach the lower surface of the substrate 31.

[0037] The optical scanning device 130 repeats laser scanning based on instructions from the control circuit 140, sequentially causing the laser light to be incident on one of the optical fibers 80. In this manner, the substrate 31 can be heated. The heating temperature can be controlled by the duration of laser light incident on the same optical fiber 80. For example, the temperature of the mounting surface 31a of the substrate 31 can be heated to approximately 200°C by the laser light propagating through the optical fiber 80.

[0038] Figure 4The use of the laser irradiation device 100 in the embodiment may be replaced by a configuration in which a number of laser light sources equal to the number of optical fibers 80 are prepared so that laser light from each laser light source can be incident on a corresponding one of the optical fibers 80. Alternatively, a fiber laser may be used in which a low-reflection mirror is provided at the end portion on the exit side of the optical fiber 80 and a high-reflection mirror is provided at the end portion on the incident side of the optical fiber 80, and excitation light is caused to enter from the end portion on the incident side of the optical fiber 80.

[0039] Here, effects obtained by the electrostatic chuck 30 constituting the substrate holding device 1 will be described while giving a comparative example.

[0040] Figure 5 1 is a schematic cross-sectional view showing a substrate fixing device according to a comparative example in a simplified manner. Figure 5 , the substrate fixing device 1X and the substrate fixing device 1 (see Figure 1 The difference between the embodiment and the embodiment is that the electrostatic chuck 30X is used instead of the electrostatic chuck 30.

[0041] The electrostatic chuck 30X has a base 31, an electrostatic electrode 32, a heating element 33, and wiring (wiring) 36 as main components. Figure 2 In a similar or identical manner to that in FIG. 3 , a plurality of temperature controllable regions 31 e whose temperatures can be independently controlled are defined in the base 31. Figure 3 In a manner similar to or identical to the case of the optical fiber 80 in FIG. 1 , a heating element 33 is disposed in each temperature-controllable region 31 e. The heating elements 33 disposed in each temperature-controllable region 31 e are isolated from one another. By varying the current flowing into each heating element 33, the amount of heat generated by each heating element 33 can be independently varied.

[0042] One end of the heating element 33 is connected to an input / output IN1 wire 65 via a wiring 36. The wire 65 is led outside the substrate holding device 1X. The other end of the heating element 33 is connected to an input / output IN2 wire 66. The wire 66 is led outside the substrate holding device 1X. The total number of wires 65 and 66 is the number of heating elements 33 plus one. For example, if there are one hundred heating elements 33, the total number of wires 65 and 66 is one hundred and one.

[0043] For example, one of the wires 65 and each of the wires 66 is connected to GND, and the other of the wires 65 and 66 is connected to a power source. The amount of heat generated by each heating element 33 can be changed by applying a voltage value between opposite ends of the heating element via the wires 65 and 66. Alternatively, a constant voltage (pulse voltage) can be applied between opposite ends of each heating element via the wires 65 and 66. In this case, the amount of heat generated by the heating element 33 can be changed by changing the time for which the voltage is supplied to the heating element 33.

[0044] The relatively large current required to generate heat in the heating element 33 flows through the wires 65 and 66. Because strong insulation is required between the base plate 10, to which high-frequency power for controlling plasma is applied, and the wires 65 and 66, the diameter of each through-hole 10z in the base plate 10, through which the wires 65 and 66 are arranged, is, for example, 5 mm. Furthermore, the diameter of the wires 65 and 66 is, for example, 4 mm. Therefore, as the total number of wires 65 and 66 increases, the area occupied by the through-holes in the base plate 10 becomes so large that it cannot be ignored.

[0045] For example, assuming that according to Figure 5 In the structure of the substrate fixture 1X of the comparative example shown, the number of temperature-controllable areas 31e is 100. In this case, more than one hundred wires are required for electrical connection between the substrate fixture and the outside. Therefore, these more than one hundred wires must be led to the outside through through-holes 10z formed in the base plate 10. In this case, as described above, the area occupied by the through-holes 10z in the base plate 10 becomes too large to be ignored, and the degree of freedom in designing the base plate 10 is significantly reduced.

[0046] In addition, in the case of the substrate holding device 1, the same number of optical fibers 80 as the number of temperature control zones 31e is required. However, as described above, the diameter of each through hole 10z in which the electric wires 65 and 66 are arranged in the substrate holding device 1X is approximately φ5 mm, while the diameter of each through hole 10x in which the optical fiber 80 is arranged in the substrate holding device 1 is approximately φ0.5 mm, which is approximately one tenth of the diameter of the through hole in which the electric wires 65 and 66 are arranged.

[0047] Therefore, even in the case where a large number of through holes 10x in which the optical fibers 80 are arranged are provided in the base plate 10, the area occupied by the through holes 10x in the base plate 10 is significantly reduced compared to the case where the same number of through holes in which the electric wires 65 and 66 are arranged are provided in the base plate 10. That is, even in the case where a large number of through holes 10x are provided in the base plate 10, the substrate fixing device 1 can suppress a reduction in the degree of freedom for designing the base plate 10.

[0048] Furthermore, the heat-generating portion of substrate fixture 1 lacks electrical connections between substrate fixture 1 and the outside world. This reduces the number of components required for external connections, thereby reducing costs. Furthermore, solder used for electrical connections between substrate fixture 1 and the outside world is eliminated. Consequently, due to the significant reduction in the number of solder joints, assembly difficulty is significantly reduced, enabling improved production yields and reliability of substrate fixture 1. Since electrostatic chuck 30 is a consumable component, the cost reduction achieved through increased production yields is significant.

[0049] Furthermore, the optical fiber 80 does not need to be electrically insulated from the base plate 10. Therefore, no insulating material or the like is required in each through hole 10x, which also leads to a reduction in cost.

[0050] (Variation 1 of the First Embodiment)

[0051] An example in which the position of the leading end of each optical fiber is retracted downward is shown in Modification 1 of the first embodiment. In Modification 1 of the first embodiment, descriptions of constituent elements having the same reference numerals as those in the above-described embodiment may be omitted.

[0052] Figure 6 1 is a partially enlarged cross-sectional view enlarging a peripheral portion of one of the optical fibers in a substrate fixing device 1A according to Modification 1 of the first embodiment.

[0053] exist Figure 1 In the embodiment, the front ends of the optical fibers 80 are respectively located in the through holes 10x formed in the adhesive layer 20. Figure 6 In the substrate fixing device 1A in FIG. 1 , the front ends of the optical fibers 80 are respectively located in the through holes 10 x formed in the base plate 10 , but do not enter the through holes 10 x formed in the adhesive layer 20 .

[0054] Due to the difference in thermal expansion coefficient between the base plate 10 and the base 31, the base 31 is generally offset in the horizontal direction relative to the base plate 10 depending on the temperature conditions. In this case, the adhesive layer 20 is also offset. 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 deteriorated). Figure 6 As shown, the tip of the optical fiber 80 is located in the through-hole 10x formed in the base plate 10, but does not enter the through-hole 10x formed in the adhesive layer 20. Therefore, the tip of the optical fiber 80 can be protected from damage (such as degradation). The offset of the base 31 relative to the base plate 10 is greater toward the outer periphery of the base 31. Therefore, a particularly significant effect is achieved in those through-holes 10x arranged on the outer periphery of the base plate 10.

[0055] (Variation 2 of the First Embodiment)

[0056] Modification 2 of the first embodiment shows an example in which a recess is provided at a position of the base 31 irradiated with laser light from the optical fiber 80. In Modification 2 of the first embodiment, description of constituent elements having the same reference numerals as those in the above embodiment may be omitted.

[0057] Figure 7 1 is a partially enlarged cross-sectional view showing an enlarged portion of a peripheral portion of one of the optical fibers 80 in the substrate fixing device 1B according to the modification 2 of the first embodiment. Figure 7 As shown, the base 31 in the substrate fixture 1B has a recess 31x formed in one side of the bottom plate 10. Laser light propagated through the optical fiber 80 is irradiated into the recess 31x. The recesses 31x are connected to the through holes 10x. However, the recesses 31x and the through holes 10x may have different diameters.

[0058] exist Figure 7 In the embodiment, the laser light L emitted from each optical fiber 80 is radiated to the bottom and side surfaces of the corresponding one of the concave portions 31x. For example, since each concave portion 31x is formed in a circular shape, Figure 1 or Figure 6 Compared with the case of FIG. 5 , the area of the base 31 irradiated with the laser light L increases. Therefore, the base 31 can be easily heated.

[0059] (Variation 3 of the First Embodiment)

[0060] Modification 3 of the first embodiment illustrates a substrate holding device 1C by way of example. The substrate holding device 1C includes an electrostatic chuck having a heating element built into a base 31. The heating element generates heat due to a voltage applied from the outside. In Modification 3 of the first embodiment, descriptions of components having the same reference numerals as those in the above-described embodiment may be omitted.

[0061] Figure 8 1 is a schematic cross-sectional view showing a substrate fixing device 1C according to a third modification of the first embodiment in a simplified manner. Figure 8 , the substrate fixing device 1C and the substrate fixing device 1 (see Figure 1 The difference between the electrostatic chuck 30 and the electrostatic chuck 30C is that the electrostatic chuck 30 is replaced by the electrostatic chuck 30. Figure 1 The difference from the embodiment of the present invention is that a heating element 40, an input / output IN1 wire 68, and an input / output IN2 wire 69 are added.

[0062] For example, the heating element 40 built into the electrostatic chuck 30C can be arranged on the side of the base plate 10 in the thickness direction of the electrostatic electrode 32. For example, the heating element 40, which is a single resistor formed in a spiral pattern or the like, is arranged to heat the entire mounting surface 31a of the substrate 31 across the plurality of temperature-controllable regions 31e. As the material of the heating element 40, for example, tungsten (W), copper (Cu), nickel (Ni), constantan (Cu / Ni / Mn / Fe alloy), etc. can be used. For example, the thickness of the heating element 40 is approximately 20 μm to 100 μm.

[0063] One end of the heating element 40 is connected to an input / output IN1 wire 68. Wire 68 is led outside the substrate holding device 1C. The other end of the heating element 40 is connected to an input / output IN2 wire 69. Wire 69 is led outside the substrate holding device 1C. There are one wire 68 and one wire 69.

[0064] For example, one of the wires 68 and 69 is connected to the ground GND, and the other of the wires 68 and 69 is connected to a power source. The amount of heat generated by the heating element 40 can be changed by applying a voltage value between the opposite ends of the heating element 40 via the wires 68 and 69. Alternatively, a constant voltage (pulse voltage) can be applied between the opposite ends of the heating element 40 via the wires 68 and 69. In this case, the amount of heat generated by the heating element 40 can be changed by changing the time for which the voltage is applied to the heating element 40.

[0065] Therefore, the heating element 40 can be built into the base 31. When current is passed through the heating element 40 to heat the mounting surface 31a of the base 31, only the portion of the mounting surface 31a that is not sufficiently heated is heated by the laser light emitted from the optical fiber 80. With this arrangement, the entire mounting surface 31a of the base 31 can be uniformly heated.

[0066] In the above description, the heating element 40 is configured as a single resistor. However, the heating element 40 may be configured as a plurality of independent resistors so that the temperatures of the plurality of zones can be independently controlled.

[0067] For example, in addition to semiconductor wafers such as silicon wafers, glass substrates used in the process of manufacturing liquid crystal panels and the like can be exemplified as objects adsorbed by the substrate fixing device according to the present disclosure.

[0068] Furthermore, in the present embodiment, the laser light emitted from the laser light source 110 is guided to each optical fiber 80 and then radiated from the front end of the optical fiber 80 toward the base 31. However, the present embodiment is not limited thereto. For example, a plurality of laser light sources may be arranged on the lower surface 10b of the base plate 10 (see FIG. Figure 1). In this case, each laser light source may be arranged to face a corresponding one of the through holes 10x formed in the base plate 10. The laser light emitted from each laser light source may be radiated toward the base 31 after passing through the corresponding one of the through holes 10x. In addition, in this case, the base 31 can also be heated by the laser light emitted from each laser light source.

[0069] Although the preferred embodiments and the like have been described in detail, the present invention is not limited to the above-described embodiments and the like, and various modifications and substitutions can be made in the above-described embodiments and the like without departing from the scope of the claims.

[0070] This application claims the benefit of Japanese Patent Application No. 2020-014638, filed on January 31, 2020, which is hereby incorporated by reference herein in its entirety.

Claims

1. A substrate fixing device, comprising: an electrostatic chuck configured to adsorb and hold an object thereon, wherein the electrostatic chuck includes a base on which the object is mounted and an electrostatic electrode provided in the base; as well as a bottom plate on which the electrostatic chuck is mounted, and wherein the bottom plate has a plurality of through holes, each of the plurality of through holes exposing a first surface of the substrate facing the bottom plate, wherein a laser is emitted from each of the through holes toward the substrate, The substrate fixing device further includes: a plurality of optical fibers, each of the plurality of optical fibers being configured to emit laser light toward the substrate and being arranged in a corresponding one of the through holes, wherein a plurality of recesses are formed in the first surface of the base body, Each of the recesses faces a corresponding one of the optical fibers, and The base is made of ceramic, the ceramic of the base is exposed from the bottom surface and the side surface of each of the recesses, and the laser light emitted from each of the optical fibers is irradiated onto the ceramic of the base exposed from the bottom surface and the side surface of each of the recesses.

2. The substrate fixing device according to claim 1, wherein: The substrate is divided into a plurality of regions; Each of the temperatures of the zones is independently controlled; and Each of the optical fibers is arranged in a corresponding one of the regions.

3. The substrate fixing device according to claim 2, wherein: A first optical fiber of the optical fibers is arranged in a first region of the regions; and Laser light emitted from the first optical fiber is radiated toward the first region, so that the first region is heated.

4. The substrate fixing device according to any one of claims 1 to 3, wherein: The substrate contains aluminum oxide as a main component, and the wavelength band of the laser light is an infrared region.

5. The substrate fixing device according to any one of claims 1 to 3, further comprising: an adhesive layer disposed between the first surface of the substrate and the bottom plate to fix the electrostatic chuck and the bottom plate to each other, in: The through holes are formed in the bottom plate and the adhesive layer so as to expose the first surface of the base; and The leading end of the optical fiber is positioned in the through hole formed in the adhesive layer.

6. The substrate fixing device according to any one of claims 1 to 3, wherein: The electrostatic chuck further includes a heating element disposed in the base.

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