electrostatic chuck

Abstract

This invention provides a technology for stably adsorbing a substrate while suppressing deformation of the substrate in an electrostatic chuck. [Solution] The electrostatic chuck 100 comprises a ceramic substrate 110 and a metal electrostatic adsorption electrode 126 embedded in the ceramic substrate 110. The upper surface 111 of the ceramic substrate 110 has a plurality of protrusions 156 that project upward from the upper surface 111, and a plurality of recesses 158 arranged to surround each of the protrusions 156.

Description

[[Technical Field]]

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

[0002] Conventionally, there has been known an electrostatic chuck in which an electrostatic chucking electrode made of a metal having predetermined dimensions (such as tungsten, molybdenum, or alloys thereof) is embedded in a ceramic sintered body (ceramic base material) such as AlN ceramics (see, for example, Patent Document 1). In the electrostatic chuck described in Patent Document 1, a plurality of convex portions (pins) are formed on a substrate mounting surface, and a substrate such as a silicon wafer is supported in contact with the upper surfaces of the convex portions. Grooves are formed around the convex portions on the substrate mounting surface to suppress the electrostatic adsorption force around the convex portions on the substrate mounting surface and thereby suppress deformation of the substrate around the convex portions. [[Prior Art Literature]] [[Patent Literature]]

[0003] [[Patent Document 1]] International Publication No. WO2024 / 057973 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] According to the findings of the inventors, when a groove is formed so as to surround the periphery of a convex portion on a substrate mounting surface, the electrostatic adsorption force is reduced over the entire periphery of the convex portion, so there is a risk that the substrate cannot be stably adsorbed.

[0005] The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique for stably adsorbing a substrate while suppressing deformation of the mounted substrate in an electrostatic chuck. [[Means for Solving the Problem]]

[0006] According to an aspect of the present invention, there is provided a plate-shaped ceramic member having a first main surface and a second main surface vertically opposing the first main surface, The ceramic member comprises an electrostatic adsorption electrode embedded in the ceramic member, The first main surface of the ceramic member is Multiple protrusions projecting upward from the first main surface, An electrostatic chuck is provided having a plurality of recesses located so as to surround the protrusions in a non-protrusion region of the first main surface where the plurality of protrusions are not provided, and / or a plurality of recesses located on the upper surface of the plurality of protrusions. [Effects of the Invention]

[0007] Since multiple protrusions are arranged on the first main surface of the ceramic substrate, the substrate on which it is placed, such as a silicon wafer, comes into contact with the first main surface of the multiple protrusions. If recesses are not provided around each protrusion, the electrostatic attraction force around the protrusions will be large, which may lead to increased substrate deflection. On the other hand, if grooves are provided surrounding the protrusions, the electrostatic attraction force will decrease throughout the area around the protrusions, which may prevent the substrate from being stably attracted. For example, if multiple recesses are arranged so as to surround each of the multiple protrusions, unlike when grooves are formed surrounding the protrusions, the electrostatic attraction force around the protrusions can be partially reduced. This can suppress excessive substrate deflection and allow the substrate to be stably attracted. In addition, when a substrate is placed on the first main surface of the protrusions, contact with the substrate may cause the ceramic particles constituting the protrusions to detach. Multiple recesses are provided around the protrusions or on the first main surface of the protrusions. Therefore, the ceramic particles generated by detachment can be captured in the recesses, and the transfer of these ceramic particles to the substrate is suppressed. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram illustrating the electrostatic chuck 100. [Figure 2] Figure 2 is a schematic diagram illustrating the shapes of the multiple protrusions 156 and recesses 158. [Figure 3] Figure 3 is a schematic diagram illustrating the shapes of the multiple protrusions 156. [Figure 4] Figure 4 is a schematic diagram illustrating the shape of the electrostatic adsorption electrode 126. [Figure 5] Figure 5 is a schematic diagram illustrating the shape of the heater electrode 122. [Figure 6] Figures (a) to (e) show the flow of the manufacturing method for the ceramic substrate 110. [Figure 7] Figures (a) to (d) show the flow of another method for manufacturing the ceramic substrate 110. [Figure 8] Figure 8 is a schematic diagram illustrating the shape of the recess 258. [Figure 9] Figure 9 is a schematic diagram illustrating the shape of the recess 358. [Figure 10] Figure 10 is a schematic diagram illustrating the shape of the recess 458. [Figure 11] Figure 11 is a schematic diagram illustrating the ceramic substrate 110 and the susceptor 150. [Modes for carrying out the invention]

[0009] <Electrostatic Chuck 100> An electrostatic chuck 100 according to an embodiment of the present invention will be described with reference to Figure 1. The electrostatic chuck 100 according to this embodiment is a substrate holding member for adsorbing and holding a semiconductor wafer such as a silicon wafer (hereinafter simply referred to as wafer 10). In the following description, the vertical direction 5 is defined based on the state in which the electrostatic chuck 100 is installed for use (the state in Figure 1). As shown in Figure 1, the electrostatic chuck 100 according to this embodiment mainly comprises a ceramic substrate 110, a heater electrode 122, and an electrostatic adsorption electrode 126. The heater electrode 122 and the electrostatic adsorption electrode 126 are sometimes collectively referred to as the electrode 120.

[0010] The ceramic substrate 110 is a circular, plate-shaped component with a diameter of 12 inches (approximately 300 mm), and the wafer 10 to be held is placed on its upper surface 111. In Figure 1, the wafer 10 and the ceramic substrate 110 are shown separated for clarity. As shown in Figure 1, the upper surface 111 of the ceramic substrate 110 is provided with an annular protrusion 152 (hereinafter simply referred to as the annular protrusion 152) and a plurality of protrusions 156. In Figure 1, the number of protrusions 156 is reduced for clarity. Also, as shown in Figure 1, a first gas channel 164, which will be described later, is formed inside the ceramic substrate 110. The ceramic substrate 110 can be formed from, for example, a ceramic sintered body of aluminum nitride, silicon carbide, alumina, silicon nitride, etc.

[0011] As shown in Figure 1, the annular projection 152 is an annular projection located on the outer periphery (outer edge) of the upper surface 111 of the ceramic substrate 110, and protrudes upward from the upper surface 111. When the wafer 10 is placed on the ceramic substrate 110, the upper surface 152a of the annular projection 152 abuts against the lower surface of the wafer 10. In other words, when the wafer 10 is placed on the ceramic substrate 110, the annular projection 152 is positioned to overlap with the wafer 10 in the vertical direction 5. On the upper surface 111 of the ceramic substrate 110, inside the annular projection 152, there are a plurality of projections 156 and a plurality of recesses 158. The plurality of projections 156 are examples of projections of the present invention, and the plurality of recesses 158 are examples of recesses of the present invention.

[0012] The multiple protrusions 156 have a cylindrical shape (cylindrical or frustoconical shape). The shape of the upper surface 156a of the multiple protrusions 156 is circular, and the outer diameter of the upper surface 156a is Φ0.1 mm to 1.5 mm. Note that the multiple protrusions 156 do not necessarily have to be strictly cylindrical or frustoconical in shape; they may be approximately cylindrical or approximately frustoconical. In Figure 1, for the sake of simplifying the drawing, one of the multiple protrusions 156 is shown positioned approximately at the center of the upper surface 111, and the remaining protrusions 156 are shown arranged on the circumference of four concentric circles arranged at equal intervals. In the non-protruding areas of the upper surface 111 of the ceramic substrate 110 where the multiple protrusions 156 are not formed, multiple recesses 158 are arranged so as to surround each of the multiple protrusions 156. As shown in Figure 2, in this embodiment, each of the multiple protrusions 156 is surrounded by four recesses 158. Here, let d1 be the distance between a certain protrusion 156 and an adjacent protrusion 156, and let d2 be the distance between a certain protrusion 156 and one of the four recesses 158 surrounding it. <d1 / 2となっている。

[0013] It should be noted that what is shown in FIG. 1 is merely an example, and the positions, shapes, and / or numbers of the protrusions 156 and the recesses 158 are appropriately set according to the application, action, and function. For example, the protrusions 156 can be arranged at lattice points of an equilateral triangle or a regular square. In this case, the interval (pitch) between adjacent protrusions 156 can be set to 1 mm to 20 mm. If the pitch is too small, when a heat transfer gas is sealed in the gap between the wafer 10 and the ceramic base material 110 to perform heat transfer by the heat transfer gas, the contact area between the heat transfer gas and the wafer 10 becomes too small, and there is a risk that a sufficient heat transfer effect cannot be obtained. In contrast, if the pitch is too large, when the wafer 10 is bent by the electrostatic adsorption force, the wafer 10 comes into contact with the upper surface 111 of the ceramic base material 110, and there is a risk that the uniformity of the temperature distribution of the wafer 10 is impaired. In particular, when the electrostatic adsorption force around the protrusions 156 is large, it is considered that the bending of the wafer 10 becomes large. However, when a groove surrounding the protrusions 156 is provided, the electrostatic adsorption force decreases over the entire periphery of the protrusions 156, so there is a risk that the wafer 10 cannot be stably adsorbed. Therefore, in the present embodiment, a plurality of recesses 158 are arranged so as to respectively surround each of the plurality of protrusions 156. In this case, unlike the case of forming a groove surrounding the protrusions 156, the electrostatic adsorption force can be partially reduced around the protrusions 156. Thereby, it is possible to suppress the bending of the wafer 10 from becoming excessively large, and to stably adsorb the wafer 10.

[0014] The height of the annular projection 152 can be in a range of 5 µm to 50 µm. Similarly, the height of the plurality of projections 156 can also be in a range of 5 µm to 50 µm. The height of the annular projection 152 and the plurality of projections 156 is preferably 5 µm to 15 µm. The depth of the plurality of recesses 158 is preferably 5 µm to 100 µm. In the present specification, the height of the plurality of projections 156 and the annular projection 152 is defined as the length in the vertical direction from the upper surface 111 of the ceramic substrate 110 to the upper surface 156a of the plurality of projections 156. Similarly, the depth of the plurality of recesses 158 is defined as the length in the vertical direction from the upper surface 111 of the ceramic substrate 110 to the deepest point of the plurality of recesses 158.

[0015] For the plurality of projections 156, the angle formed between the upper surface 156a and the side surface 156s is preferably not less than 90° and not more than 170° (see FIG. 3). For example, in a case where the plurality of projections 156 are formed by machining using a grindstone, the angle formed between the upper surface 156a and the side surface 156s can be set to not less than 91° and not more than 150° by changing the shape of the grindstone. Further, in a case where the plurality of projections 156 are formed by sandblasting, the angle formed between the upper surface 156a and the side surface 156s can be set to not less than 120° and not more than 170°.

[0016] Rounding (R10 µm to R50 µm) can be performed between the upper surface 156a and the side surface 156s of the plurality of projections 156. By performing the rounding, the contact between the upper surface 156a of the projection 156 and the wafer 10 is stabilized. In the case of performing the rounding, reducing the radius of the R can increase the contact area between the upper surface 156a and the wafer 10, and improves the heat transfer effect. However, if the radius of the R is too small, particles (having a diameter of about 2 µm to 7 µm) constituting the ceramic may fall off due to contact with the wafer 10. Therefore, by making the radius of the R larger than the particle diameter of the fallen particles (for example, setting the radius of the R to 10 µm or more), falling off of ceramic particles due to contact with the wafer 10 can be suppressed.

[0017] The outer diameter of the multiple recesses 158 can be 0.1 mm to 1.5 mm, and the depth can be 5 μm to 100 μm. The multiple recesses 158 can be formed by sandblasting, etching, machining, etc.

[0018] In this embodiment, the centerline average roughness Ra of the upper surface 111 of the ceramic substrate 110 is 0.1 μm to 3 μm. In contrast, the centerline average roughness Ra of the upper surfaces 156a of the multiple protrusions 156 and the upper surfaces 158a of the multiple recesses 158 is preferably 0.01 μm to 2 μm.

[0019] As shown in Figure 1, an opening 164a of the first gas channel 164 is formed between the innermost concentric circle and the second-to-last concentric circle on the upper surface 111 of the ceramic substrate 110, where a plurality of protrusions 156 are arranged. The first gas channel 164 is a gas channel with an opening 164a and is formed inside the ceramic substrate 110. The first gas channel 164 extends downward from the opening 164a.

[0020] The first gas channel 164 can be used as a channel for supplying gas to the space (gap) defined by the upper surface 111 of the ceramic substrate 110 and the lower surface of the wafer 10. For example, it can supply heat transfer gas for heat transfer between the wafer 10 and the ceramic substrate 110. As the heat transfer gas, for example, an inert gas such as helium or argon, or nitrogen gas can be used. The heat transfer gas is supplied through the first gas channel 164 at a pressure set within the range of 100 Pa to 40000 Pa. In addition, if process gas enters the gap inside the annular protrusion 152 from the gap between the upper surface 152a of the annular protrusion 152 and the lower surface of the wafer 10, the gas can be exhausted through the first gas channel 164. In this case, the differential pressure between the pressure outside the gap and the pressure inside the gap can be adjusted by adjusting the exhaust pressure. This makes it possible to adsorb the wafer 10 toward the upper surface of the ceramic substrate 110.

[0021] As shown in Figure 1, a heater electrode 122 and an electrostatic adsorption electrode 126 are embedded inside the ceramic substrate 110. The heater electrode 122 and the electrostatic adsorption electrode 126 can be formed from a mesh, foil, or plate material woven from wires of tungsten (W), molybdenum (Mo), or an alloy containing molybdenum and / or tungsten. As shown in Figure 4, the electrostatic adsorption electrode 126 has two semicircular electrodes 126a and 126b arranged opposite each other at a predetermined distance apart, and has an overall substantially circular shape. For example, the outer diameter of the electrostatic adsorption electrode 126 can be 298 mm. By applying a predetermined voltage (e.g., ±500 V) to electrodes 126a and 126b via terminal 126T, the wafer 10 can be electrostatically adsorbed. Furthermore, if the electrostatic adsorption electrode 126 is formed from a mesh or a foil or plate material (perforated plate) having multiple openings 128 (see Figure 4), the electrostatic adsorption force can be adjusted by adjusting the ratio of openings.

[0022] As shown in Figure 5, the heater electrode 122 is formed from a metal mesh or foil cut into strips. The heater electrode 122 is made of a heat-resistant metal (high melting point metal) such as tungsten (W), molybdenum (Mo), or an alloy containing molybdenum and / or tungsten. The outer diameter of the heater electrode 122 is 298 mm. The heater electrode 120 is not exposed from the side surface of the ceramic substrate 110. A terminal portion 122T, which is connected to a power supply line (not shown), is provided approximately in the center of the heater electrode 122. The thickness of the heater electrode 122 is 0.15 mm or less. When the heater electrode 122 is formed from mesh, the thickness refers to the value excluding the wire intersections. From the viewpoint of increasing the resistance of the heater electrode 122 and reducing the current consumption of the ceramic heater 100, it is preferable to make the wire diameter 0.1 mm or less and the thickness of the heater electrode 122 0.1 mm or less, excluding the wire intersections. In particular, it is preferable that the wire diameter be 0.03 mm or more and 0.05 mm or less. Furthermore, the width of the strip-shaped heater electrode 122 is preferably 2.5 mm to 20 mm, and more preferably 5 mm to 15 mm. In this embodiment, the heater electrode 122 is cut into the shape shown in Figure 5, but the shape of the heater electrode 122 is not limited to this and can be changed as appropriate.

[0023] Next, the manufacturing method of the electrostatic chuck 100 will be described. In the following explanation, we will use the case where the ceramic substrate 110 is made of aluminum nitride as an example. Also, for the sake of simplicity, we will assume that only the electrostatic adsorption electrode 126 is embedded in the ceramic substrate 110.

[0024] First, the method for manufacturing the ceramic substrate 110 will be described. As shown in Figure 6(a), granulated powder Q, mainly composed of aluminum nitride (AlN) powder, is placed in a carbon bed mold 601 and pre-pressed with a punch 602. Preferably, the granulated powder Q contains 5 wt% or less of a sintering aid (for example, Y2O3). A foil or plate of Mo with a thickness of 0.05 mm or more is prepared as the electrostatic adsorption electrode 126. Multiple through holes 128 are formed in the electrostatic adsorption electrode 126 by etching or the like. Alternatively, the electrostatic adsorption electrode 126 can be formed from a mesh woven with Mo wire having a predetermined aperture ratio. Next, as shown in Figure 6(b), the electrostatic adsorption electrode 126, cut to a predetermined shape, is placed on top of the pre-pressed granulated powder Q. The electrostatic adsorption electrode 126 is positioned parallel to the surface perpendicular to the pressurizing direction (the bottom surface of the bed mold 601). At this time, W pellets or Mo pellets may be embedded at the position of terminal 126T (see Figure 4) of the electrostatic adsorption electrode 126.

[0025] As shown in Figure 6(c), granulated powder Q is further added to the bed mold 601 so as to cover the electrostatic adsorption electrode 126, and then pressed and molded with a punch 602. At this time, the amount of granulated powder Q covering the electrostatic adsorption electrode 126 can be adjusted so that the electrostatic adsorption electrode 126 is embedded at a depth of 0.3 mm or more. Next, as shown in Figure 6(d), the granulated powder Q with the embedded electrostatic adsorption electrode 126 is fired in a pressed state. The pressure applied during firing is preferably 1 MPa or more. It is also preferable to fire at a temperature of 1800°C or higher. Multiple firings can also be performed. Next, as shown in Figure 6(e), blind holes are machined up to the electrostatic adsorption electrode 126 in order to form the terminal 126T. If pellets are embedded, blind holes should be machined up to the pellets. Furthermore, if necessary, through holes may be formed to form gas flow channels 164. This makes it possible to produce a ceramic substrate 110 with gas flow channels 164 formed inside. Furthermore, the through-hole is insulated from the heater electrode 122 and the electrostatic adsorption electrode 126 as needed. Insulation means that the electrodes are not exposed in the through-hole, or by means such as inserting an insulating sleeve into the through-hole.

[0026] The ceramic substrate 110 can also be manufactured by the following method. As shown in Figure 7(a), a binder is added to aluminum nitride granules Q and then CIP molding is performed to process it into a disc shape to produce an aluminum nitride molded body 610. Next, as shown in Figure 7(b), the molded body 610 is degreased to remove the binder.

[0027] As shown in Figure 7(c), a recess 611 for embedding the electrostatic adsorption electrode 126 is formed in the degreased molded body 610. The recess 611 may be formed in the molded body 610 in advance. As described above, a foil or plate of Mo with a thickness of 0.05 mm or more is prepared as the electrostatic adsorption electrode 126, and multiple through holes 128 are formed in the electrostatic adsorption electrode 126 by etching or punching. Alternatively, the electrostatic adsorption electrode 126 is formed from a mesh woven from Mo wires having a predetermined aperture ratio. The electrostatic adsorption electrode 126 is placed in the recess 611 of the molded body 610, and another molded body 610 is laminated on top. At this time, the thickness of the other molded body 610 can be adjusted so that the electrostatic adsorption electrode 126 is embedded at a depth of 0.3 mm or more. Next, as shown in Figure 7(d), the molded bodies 610 laminated with the electrostatic adsorption electrode 126 sandwiched in between are fired in a pressed state to produce a fired body. The pressure applied during firing is preferably 1 MPa or higher. Furthermore, firing at a temperature of 1800°C or higher is preferable. Multiple firings can also be performed. The process after the firing of the body is the same as described above, so the explanation is omitted.

[0028] The upper surface 111 of the ceramic substrate 110 formed in this manner is ground and polished. This allows adjustment of the vertical distance 5 from the upper surface 111 of the ceramic substrate 110 to the electrostatic adsorption electrode 126. For example, the vertical distance 5 from the upper surface 111 of the ceramic substrate 110 to the electrostatic adsorption electrode 126 can be adjusted to 0.3 mm or more. Furthermore, sandblasting is performed on the upper surface 111 to form a plurality of protrusions 156, recesses 158 and annular protrusions 152 on the upper surface 111. While sandblasting is preferred as the processing method for forming the plurality of protrusions 156, recesses 158 and annular protrusions 152, other processing methods can also be used.

[0029] <Effects of the Embodiment> In the above embodiment, the electrostatic chuck 100 comprises a ceramic substrate 110 and a metal electrostatic adsorption electrode 126 embedded in the ceramic substrate 110. The upper surface 111 of the ceramic substrate 110 has a plurality of protrusions 156 that project upward from the upper surface 111. The upper surfaces 156a of the plurality of protrusions 156 are located above the upper surfaces 158a of the plurality of recesses 158. In the non-protruding regions of the upper surface 111 of the ceramic substrate 110 where the plurality of protrusions 156 are not formed, a plurality of recesses 158 are arranged so as to surround each of the plurality of protrusions 156.

[0030] Since multiple protrusions 156 are arranged on the upper surface 111 of the ceramic substrate 110, the placed wafer 10 comes into contact with the upper surfaces 156a of the multiple protrusions 156. In the above embodiment, multiple recesses 158 are arranged so as to surround each protrusion 156. According to the inventors' knowledge, if recesses 158 are not provided around each protrusion 156, the electrostatic attraction force around the protrusion 156 will increase, and it is conceivable that the deflection of the wafer 10 will increase. On the other hand, if grooves are provided so as to surround the protrusion 156, the electrostatic attraction force will decrease around the protrusion 156 as a whole, so there is a risk that the wafer 10 cannot be stably attracted. Therefore, in this embodiment, multiple recesses 158 are arranged so as to surround each of the multiple protrusions 156. In this case, unlike when grooves are formed so as to surround the protrusion 156, the electrostatic attraction force around the protrusion 156 can be partially reduced. This prevents the wafer 10 from becoming excessively deflected and allows the wafer 10 to be stably adsorbed. Furthermore, when the wafer 10 is placed on the upper surface 156a of the protrusion 156, contact with the wafer 10 may cause the ceramic particles constituting the protrusion 156 to detach. In this embodiment, a plurality of recesses 158 are provided around the protrusion 156. The bottom portion of the recesses 158 is closer to the electrostatic adsorption electrode 126 than the upper surface 111 of the ceramic substrate 110, and the electrostatic adsorption force acting on the bottom portion of the recesses 158 is stronger than the electrostatic adsorption force on the upper surface 111 of the ceramic substrate 110. Therefore, ceramic particles (hereinafter referred to as particles) generated by detachment can be captured in the recesses 158, and the transfer of particles to the wafer 10 is suppressed.

[0031] In the above embodiment, when d1 is the distance between one convex portion 156 and the adjacent convex portion 156, and d2 is the distance between a certain convex portion 156 and one of the four concave portions 158 surrounding the convex portion 156, the relationship d2 < d1 / 2 is satisfied. By arranging the concave portions 158 at positions closer than the midpoint between two adjacent convex portions 156 in this manner, particles generated in the convex portions 156 surrounded by the concave portions 158 can be efficiently captured by the concave portions 158, thereby suppressing transfer of the particles to the wafer 10.

[0032] <Modified Embodiment> The above-described embodiment is merely an example, and can be modified as appropriate. For example, the shape, size, and thickness of the heater electrode 122 and the electrostatic chuck electrode 126 are not limited to those in the above embodiment, and can be modified as appropriate. Further, the heater electrode 122 does not necessarily need to be provided.

[0033] Further, the shape, thickness, and the like of the ceramic base material 110 can be modified as appropriate. Further, dimensions such as the height and width of the annular convex portion 152, and the shape of the upper surface 152a of the annular convex portion 152 can be modified as appropriate. The height of the plurality of convex portions 156 and the shape of the upper surfaces 156a thereof can be modified as appropriate. For example, the shape of the upper surfaces 156a of the plurality of convex portions 156 is not necessarily circular, and may be any appropriate shape such as a square, for example.

[0034] In the above embodiment, the recesses 158 were arranged to surround each protrusion 156. The present invention is not limited to such embodiments. For example, as shown in Figure 8, in addition to the plurality of recesses 158 provided to surround the protrusion 156, a plurality of recesses 258 can be formed so as to be distributed over the entire non-protruding region of the upper surface 111 of the ceramic substrate 110 where the plurality of protrusions 156 are not formed. In this case, the distance from a certain protrusion 156 to the recesses 158 surrounding it is shorter than the distance from the protrusion 156 to the recesses 258. The plurality of recesses 158 is an example of the first recess of the present invention, and the plurality of recesses 258 is an example of the second recess of the present invention. The outer diameter of the plurality of recesses 258 is the same as the outer diameter of the plurality of recesses 158. The depth of the plurality of recesses 158 provided to surround the protrusion 156 is deeper than the depth of the plurality of recesses 258. In this case, since multiple recesses 158 are provided near the protrusion 156, particles generated by contact between the protrusion 156 and the wafer 10 can be efficiently captured. Furthermore, since recesses 258 are provided at a position further away from the multiple recesses 158, particles that could not be captured by the recesses 158 can be captured by the recesses 258. This suppresses the transfer of particles to the wafer 10. In the above description, the outer diameter of the multiple recesses 258 was the same as the outer diameter of the multiple recesses 158, but the present invention is not limited to such an embodiment. The outer diameter of the multiple recesses 258 and the outer diameter of the multiple recesses 158 may be different.

[0035] As shown in Figure 9, a plurality of recesses 358 can be arranged at positions equally spaced from three adjacent protrusions 156. The plurality of recesses 358 is an example of the third recess of the present invention. Arranging the plurality of recesses 358 at positions equally spaced from three adjacent protrusions 156 is particularly effective when the protrusions 156 are located at the grid points of an equilateral triangle. In this case, particles generated by contact with the wafer 10 at any of the three adjacent protrusions 156 can be efficiently captured by the recesses 358 arranged at positions equally spaced from the three protrusions 156.

[0036] In the above embodiment, the recesses 158 were arranged to surround each of the multiple protrusions 156 in a non-protruding region of the upper surface 111 of the ceramic substrate 110 where no multiple protrusions 156 were formed. The present invention is not limited to such an embodiment. As shown in Figure 10, recesses 458 may be formed on the upper surface 156a of the multiple protrusions 156. In this case, particles generated by contact between the upper surface 156a of the protrusions 156 and the wafer 10 can be efficiently captured by the recesses 458 formed on the upper surface 156a of the protrusions 156. The depth of the recesses 458 is preferably 15 μm or less.

[0037] As shown in Figure 11, a susceptor 150 can be joined to the lower surface 113 of the ceramic substrate 110. The susceptor 150 has a circular plate shape with a diameter equal to or larger than that of the ceramic substrate 110, and a flow channel 130 is formed inside it. The susceptor 150 can be made of Al, conductive ceramics, ceramics, etc. The ceramic substrate 110 and the susceptor 150 can be joined using hard brazing, soft brazing, adhesives such as silicone bond, etc. Alternatively, a female screw hole and a through hole through which a screw passes can be formed in either the ceramic substrate 110 or the susceptor 150, and they can be fastened with a screw. In this case, it is preferable to form a groove for airtight sealing in either the ceramic substrate 110 or the susceptor 150, and fasten them with an airtight seal (O-ring, etc.) in between. Furthermore, when hard brazing the ceramic substrate 110 and the susceptor 150, for example, aluminum brazing material (A4047, eutectic point 577°C) can be used as the hard brazing material. These hard brazing materials may contain active metals such as Ti, Hf, and Zr. Metal foil such as Al foil can also be used as the hard brazing material. When hard brazing the ceramic substrate 110 and the ceramic susceptor 150, it is preferable to make the centerline average roughness Ra of the joining surface before joining 1.6 μm or less. Furthermore, when soft brazing the ceramic substrate 110 and the susceptor 150, for example, In, Sn, Pb, and alloys thereof (solder) can be used as the soft brazing material. Furthermore, when soft brazing the ceramic substrate 110 and the ceramic susceptor 150, it is preferable to make the centerline average roughness Ra of the joining surface before joining 1.6 μm or less. Alternatively, a thin film of Cr or Ti may be formed on the bonding surface beforehand.

[0038] Although embodiments and modified versions of the invention have been described above, the technical scope of the present invention is not limited to the scope described above. It will be obvious to those skilled in the art that various modifications or improvements can be made to the above embodiments. It is also clear from the claims that such modified or improved forms may be included in the technical scope of the present invention.

[0039] The order in which each process in the manufacturing method shown in the specification and drawings is executed is not specifically defined, and unless the output of a previous process is used in a later process, the processes can be executed in any order. Even if phrases such as "first," and "next," are used for convenience, this does not mean that the processes must be performed in that order. [Explanation of Symbols]

[0040] 100 ceramic susceptors 110 Ceramic substrate 122 Heater electrodes 126 Electrodes for electrostatic adsorption 156 Convex part 158, 258, 358, 458 recesses

Claims

1. A plate-shaped ceramic member having a first main surface and a second main surface facing the first main surface in the vertical direction, The ceramic member comprises an electrostatic adsorption electrode embedded in the ceramic member, The first main surface of the ceramic member is Multiple protrusions projecting upward from the first main surface, An electrostatic chuck having a plurality of recesses located so as to surround the protrusions in a non-protrusion region of the first main surface where the plurality of protrusions are not provided, and / or a plurality of recesses located on the upper surface of the plurality of protrusions.

2. Of the plurality of protrusions, the distance between the first protrusion and the second protrusion that is closest to the first protrusion is d. １ And, The distance between the first protrusion and the recess among the plurality of recesses that is closest to the first protrusion is d. ２ When that is the case, d ２ <d １ / 2 The electrostatic chuck according to claim 1.

3. The electrostatic chuck according to claim 1, wherein the plurality of recesses are positioned to be distributed throughout the entire non-protruding region.

4. The electrostatic chuck according to claim 1, wherein the outer diameter of the plurality of recesses is 0.1 mm to 1.5 mm and the depth is 5 μm to 100 μm.

5. The aforementioned multiple protrusions have a cylindrical or truncated cone shape. The electrostatic chuck according to claim 1, wherein the outer diameter of the upper surface of the plurality of protrusions is 0.1 mm to 1.0 mm, and the height of the plurality of protrusions is 5 μm to 50 μm.

6. The plurality of recesses include a first recess where the distance to the nearest protrusion among the plurality of protrusions is D1, and a second recess where the distance to the nearest protrusion among the plurality of protrusions is D2 (D1 < D2). The electrostatic chuck according to claim 1, wherein the outer diameter of the first recess is different from the outer diameter of the second recess, or the depth of the first recess is different from the depth of the second recess.

7. The electrostatic chuck according to claim 6, wherein the depth of the first recess is greater than the depth of the second recess.

8. The electrostatic chuck according to claim 1, wherein the plurality of recesses have a third recess that is equal in distance from three adjacent protrusions among the plurality of protrusions.

9. The electrostatic chuck according to claim 1, wherein the plurality of recesses include recesses located on the upper surface of the plurality of protrusions.

10. The electrostatic chuck according to claim 9, wherein the depth of the recess located on the upper surface of the plurality of protrusions among the plurality of recesses is 15 μm or less.

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