A brazing method for electrostatic chucks

Abstract

The application provides a brazing method of an electrostatic chuck, which comprises the following steps: (1) ESC ceramic disc pretreatment: performing sand blasting treatment on the welding surface of the ESC ceramic disc; (2) welding surface ultrasonic immersion: respectively performing heating treatment and ultrasonic immersion on the ceramic disc and the metal base after the pretreatment in step (1); (3) assembly and brazing: preparing a welding base and placing the ceramic disc, then embedding a welding clamp outside the ceramic disc to fix the ceramic disc and form a welding molten pool; filling the welding molten pool with solder, then buckling the metal base and performing pressure treatment; (4) cooling forming: removing the welding clamp after cooling treatment, and obtaining the brazing formed electrostatic chuck. For the electrostatic chuck with the area of the ESC ceramic disc being larger than that of the metal base, the brazing combination rate and success rate of the electrostatic chuck can be greatly improved by adding the welding clamp and improving the welding process, the process is simple, the cost is lower, and the welding size is accurate.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor equipment technology, and relates to a welding method for an electrostatic chuck, specifically a brazing method for an electrostatic chuck. Background Technology

[0002] In semiconductor manufacturing processes, the stable fixation and precise support of wafers are crucial for ensuring processing accuracy and improving product yield. Early semiconductor equipment primarily used mechanical clamping to hold wafers in place; however, these mechanical structures easily introduce contaminants and can cause physical damage to the wafer surface, significantly reducing the wafer's yield. As semiconductor manufacturing processes have evolved towards greater precision and higher cleanliness, mechanical clamping-free technologies have gradually become mainstream, with the electrostatic chuck (ESC) serving as its core component.

[0003] An electrostatic chuck mainly consists of two parts: an ESC ceramic disc and a metal base. The connection between these two parts directly determines the heat conduction performance, structural stability, and service life of the electrostatic chuck. Currently, the mainstream connection methods in the industry are divided into two categories: organic thermally conductive adhesive bonding and solder brazing.

[0004] CN 105845613A discloses an electrostatic chuck and its manufacturing method. The manufacturing method includes: providing a cooling base, and fabricating a multilayer structure on the cooling base comprising sequentially stacked thermally conductive adhesive, an insulating layer, an electrode layer, a dielectric layer, and a carbonized layer. The dielectric layer, on which the electrode layer is formed, is sintered once and then sintered a second time with the insulating layer to achieve atomic bonding. Although this method is relatively simple to operate, the thermal conductivity of the organic thermally conductive adhesive is much lower than that of metal materials, which limits the heat transfer efficiency of the electrostatic chuck and cannot meet the high heat dissipation requirements of advanced processing scenarios.

[0005] CN 115116920A discloses an electrostatic chuck and its processing method. The processing method includes: forming a metal transition layer on the surface of a ceramic disk; and welding a base to the surface of the ceramic disk with the metal transition layer using metal solder. While this method uses metal solder to improve heat conduction efficiency to some extent, gold-based and silver-based solders are expensive, and the surface of the ceramic disk or metal base needs to be pre-treated with a coating before welding, resulting in a complex process and long production time.

[0006] In addition, when the area of ​​the ESC ceramic disk is larger than that of the metal base, the existing welding process is difficult to ensure uniform bonding at the interface between the two, which can easily lead to localized incomplete welding and insufficient bonding rate. This results in a significant reduction in the yield of the electrostatic chuck and further increases production and maintenance costs.

[0007] In summary, developing a connection solution suitable for electrostatic chucks with large ceramic disc areas to simplify the process, reduce material costs, and improve welding bonding rate and production yield has become an urgent technical need to be addressed in this field. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a brazing method for electrostatic chucks. For electrostatic chucks with ESC ceramic discs larger than their metal bases, this invention significantly improves the bonding rate and success rate of electrostatic chuck welding by adding welding fixtures and improving the welding process. Furthermore, the process is simple, lower in cost, and produces precise welding dimensions.

[0009] To achieve this objective, the present invention adopts the following technical solution: This invention provides a brazing method for an electrostatic chuck, the electrostatic chuck comprising an ESC ceramic disk and a metal base, wherein the diameter of the ESC ceramic disk is greater than the diameter of the metal base; The brazing method includes the following steps: (1) Pretreatment of ESC ceramic disk: The welding surface of the ESC ceramic disk is sandblasted. (2) Ultrasonic impregnation of the welding surface: The ESC ceramic disk and the metal base after the pretreatment in step (1) are heated and then the welding surface is ultrasonically impregnated. (3) Assembly and brazing: Prepare the welding base and place the ESC ceramic disk, and then nest the welding fixture on the outside of the ESC ceramic disk to fix the ESC ceramic disk and form a welding pool at the same time. Fill the weld pool with solder, then fasten and assemble the metal base and apply pressure. (4) Cooling and forming: After cooling, the welding fixture is removed to obtain the electrostatic chuck formed by brazing.

[0010] For electrostatic chucks with an ESC ceramic disc area larger than the metal base, this invention can significantly improve the bonding rate and success rate of electrostatic chuck welding by adding welding fixtures and improving the welding process. Moreover, the process is simple, the cost is lower, and the welding dimensions are accurate.

[0011] As a preferred technical solution of the present invention, the particle size of the sand used in the sandblasting process in step (1) is 30~60 mesh, for example, it can be 30 mesh, 40 mesh, 50 mesh or 60 mesh, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0012] Preferably, the roughness of the welding surface of the ESC ceramic disk after sandblasting in step (1) is 5~8μm, for example, it can be 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm or 8μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0013] In this invention, the sandblasting process in step (1) is preceded by a masking process; the specific process of the masking process is: using protective tape to cover the area on the edge of the ESC ceramic disk that does not need to contact the solder.

[0014] As a preferred technical solution of the present invention, the heating rate of the heating treatment in step (2) is 2~3℃ / min, for example, it can be 2℃ / min, 2.2℃ / min, 2.4℃ / min, 2.6℃ / min, 2.8℃ / min or 3℃ / min, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0015] Preferably, the final temperature of the heating treatment in step (2) is 220~240℃, for example, it can be 220℃, 225℃, 230℃, 235℃ or 240℃, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0016] As a preferred technical solution of the present invention, the wetting medium used in step (2) for ultrasonic wetting is brazing solder melt.

[0017] Preferably, the brazing solder melt includes tin-based solder or indium-based solder.

[0018] Preferably, the ultrasonic immersion time in step (2) is 25 to 40 minutes, for example, it can be 25 minutes, 30 minutes, 35 minutes or 40 minutes, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] Preferably, the ultrasonic frequency of the ultrasonic immersion in step (2) is 30~50kHz, for example, it can be 30kHz, 34kHz, 38kHz, 42kHz, 46kHz or 50kHz, but is not limited to the listed values. Other values ​​not listed in the range are also applicable.

[0020] As a preferred technical solution of the present invention, after the snap-fit ​​assembly in step (3), the concentricity of the ESC ceramic disk and the metal base is <0.5mm, for example, it can be 0.45mm, 0.4mm, 0.35mm, 0.3mm, 0.25mm, 0.2mm or 0.15mm, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0021] Preferably, after the snap-fit ​​assembly in step (3), a gap is left between the welding fixture and the ESC ceramic disk and the metal base.

[0022] Preferably, the width of the gap is 0.3~0.5mm, for example, it can be 0.3mm, 0.34mm, 0.38mm, 0.42mm, 0.46mm or 0.5mm, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0023] In this invention, the welding fixture is in the shape of a double ring, including a ceramic disc fixing ring and a base fixing ring that are fixedly disposed thereon.

[0024] Preferably, the inner diameter of the ceramic disk fixing ring is larger than the inner diameter of the base fixing ring; and the portion of the base fixing ring that protrudes from the ceramic disk fixing ring is used to shield the area of ​​the welding surface edge of the ESC ceramic disk that does not need to contact the solder, thereby preventing a large amount of solder from flowing in.

[0025] As a preferred technical solution of the present invention, step (3) further includes performing a second ultrasonic impregnation on the welding pool before the fastening assembly.

[0026] Preferably, the immersion time of the second ultrasonic immersion is 20 to 30 minutes, for example, it can be 20 minutes, 22 minutes, 24 minutes, 26 minutes, 28 minutes or 30 minutes, but it is not limited to the listed values. Other values ​​not listed within the range are also applicable.

[0027] Preferably, the immersion temperature of the second ultrasonic immersion is 220~240℃, for example, it can be 220℃, 225℃, 230℃, 235℃ or 240℃, etc., but is not limited to the listed values. Other values ​​not listed in the range are also applicable.

[0028] Preferably, the ultrasonic frequency of the second ultrasonic immersion is 30~50kHz, for example, it can be 30kHz, 34kHz, 38kHz, 42kHz, 46kHz or 50kHz, etc., but is not limited to the listed values. Other values ​​not listed in the range are also applicable.

[0029] As a preferred embodiment of the present invention, the welding surface of the metal base is uniformly and fixedly provided with a plurality of welded layer support columns.

[0030] Preferably, the height of the welded layer support columns is the same and equal to the thickness of the brazing solder layer.

[0031] As a preferred technical solution of the present invention, the pressurization process in step (3) includes: placing a force-applying object on the non-welded surface of the metal base.

[0032] Preferably, the weight of the object applying the force is 20-30 kg, for example, it can be 20 kg, 22 kg, 24 kg, 26 kg, 28 kg or 30 kg, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0033] Preferably, the temperature of the pressurization process in step (3) is 220~240, for example, it can be 220℃, 225℃, 230℃, 235℃ or 240℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] As a preferred technical solution of the present invention, the flatness of the metal base after pressure treatment is <0.5mm, for example, it can be 0.48mm, 0.46mm, 0.44mm, 0.42mm, 0.40mm or 0.38mm, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] As a preferred embodiment of the present invention, the welding fixture is made of aluminum alloy.

[0036] Preferably, the welding base is made of aluminum alloy.

[0037] Preferably, the cooling process in step (4) includes furnace cooling.

[0038] As a preferred embodiment of the present invention, the brazing method of the electrostatic chuck of the present invention includes the following steps: (1) Pretreatment of ESC ceramic disk: The area on the edge of the ceramic disk that does not need to contact the solder is masked with protective tape; then the welding surface of the ESC ceramic disk is sandblasted with sand with a particle size of 30~60 mesh to make the roughness of the welding surface of the ESC ceramic disk 5~8μm. (2) Ultrasonic wetting of the welding surface: The ESC ceramic disk and the metal base after the pretreatment in step (1) are placed on the heating table and heated to 220-240°C at a heating rate of 2-3°C / min. Then, the brazing solder molten liquid is laid on the welding surface of the ESC ceramic disk and the metal base for ultrasonic wetting. The ultrasonic immersion time is 25-40 min, and the ultrasonic frequency is 30-50 kHz. (3) Assembly and brazing: Under the condition of maintaining a temperature of 220~240℃, prepare the welding base and place the ESC ceramic disk, and then nest the welding fixture on the outside of the ESC ceramic disk to fix the ESC ceramic disk and form a welding pool at the same time. Fill the weld pool with solder, and perform a second ultrasonic immersion on the weld pool at an ultrasonic frequency of 30-50kHz for 20-30 minutes. Then, fasten and assemble the metal base and apply pressure with a force-applying object weighing 20-30kg. After the fastening assembly, a gap of 0.3~0.5mm is left between the welding fixture and the ESC ceramic disk and the metal base, and the concentricity of the ESC ceramic disk and the metal base is <0.5mm; The welding fixture is in the shape of a double ring, including a ceramic disk fixing ring and a base fixing ring that are fixedly arranged; the inner diameter of the ceramic disk fixing ring is larger than the inner diameter of the base fixing ring; and the part of the base fixing ring that protrudes from the ceramic disk fixing ring is used to shield the area of ​​the welding surface edge of the ESC ceramic disk that does not need to contact the solder. The metal base has several welded layer support columns uniformly and fixedly arranged on its welding surface. (4) Cooling and forming: After cooling, the welding fixture is removed to obtain the electrostatic chuck formed by brazing.

[0039] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0040] Compared with the prior art, the present invention has the following beneficial effects: For products where the ceramic disc area is larger than the base, this invention can greatly improve the bonding rate and success rate of electrostatic chuck welding by adding welding fixtures and improving the welding process. Moreover, the process is simple, the cost is lower, and the welding dimensions are more accurate. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the structure after fastening and assembly in Embodiment 1 of the present invention; Among them, 1 is the welding base, 2 is the welding fixture, 3 is the ESC ceramic disk, 4 is the metal base, and 5 is the welding layer support column. Detailed Implementation

[0042] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0043] The diameter of the ESC ceramic disk of the electrostatic chuck provided in the following embodiments and comparative examples is greater than the diameter of the metal base.

[0044] Example 1 This embodiment provides a brazing method for an electrostatic chuck, the brazing method comprising the following steps: (1) Pretreatment of ESC ceramic disk: The area on the edge of the ceramic disk that does not need to contact the solder is masked with protective tape; then the welding surface of the ESC ceramic disk is sandblasted with sand with a particle size of 30~60 mesh to make the roughness of the welding surface of the ESC ceramic disk 6.5μm. (2) Ultrasonic wetting of the welding surface: The ESC ceramic disk and metal base after the pretreatment in step (1) are placed on the heating table and heated to 230°C at a heating rate of 2.5°C / min. Then, tin-based brazing solder is laid on the welding surface of the ESC ceramic disk and metal base for ultrasonic wetting. The ultrasonic immersion time is 30 minutes and the ultrasonic frequency is 40 kHz. (3) Assembly and brazing: Under the condition of maintaining a temperature of 230°C, prepare the welding base 1 and place the ESC ceramic disk 3, and then nest the welding fixture 2 on the outside of the ESC ceramic disk 3 to fix the ESC ceramic disk 3 and form a welding pool at the same time. The molten pool is filled with tin-based brazing filler, and the molten pool is subjected to a second ultrasonic immersion at an ultrasonic frequency of 40kHz for 25 minutes. Then the metal base 4 is fastened and assembled and pressure is applied using a force-applying object weighing 25kg. After the fastening assembly, a gap of 0.4 mm is left between the welding fixture 2 and the ESC ceramic disk 3 and the metal base 4, and the concentricity of the ESC ceramic disk 3 and the metal base 4 is 0.4 mm. The welding fixture 2 is in the shape of a double ring, including a ceramic disk fixing ring and a base fixing ring that are fixedly arranged; the inner diameter of the ceramic disk fixing ring is larger than the inner diameter of the base fixing ring; and the part of the base fixing ring that protrudes from the ceramic disk fixing ring is used to shield the area of ​​the welding surface edge of the ESC ceramic disk that does not need to contact the solder. The metal base 4 has a plurality of weld layer support columns 5 uniformly fixedly arranged on its welding surface, and the height of the weld layer support columns 5 is the same and equal to the thickness of the brazing solder layer. (4) Cooling and forming: After cooling, the welding fixture is removed to obtain the electrostatic chuck formed by brazing.

[0045] The structural diagram corresponding to the snap-fit ​​assembly in this embodiment is as follows: Figure 1 As shown.

[0046] Example 2 This embodiment provides a brazing method for an electrostatic chuck, the brazing method comprising the following steps: (1) Pretreatment of ESC ceramic disk: Protective tape is used to cover the area of ​​the ceramic disk edge that does not need to contact the solder; then, sandblasting is performed on the welding surface of the ESC ceramic disk with 30-mesh sand to make the roughness of the welding surface of the ESC ceramic disk 8μm. (2) Ultrasonic wetting of the welding surface: The ESC ceramic disk and the metal base after the pretreatment in step (1) are placed on the heating table and heated to 220°C at a heating rate of 2°C / min. Then, indium-based brazing solder is laid on the welding surface of the ESC ceramic disk and the metal base for ultrasonic wetting. The ultrasonic immersion time is 25 minutes and the ultrasonic frequency is 20 kHz. (3) Assembly and brazing: Under the condition of maintaining a temperature of 220°C, prepare the welding base and place the ESC ceramic disk, and then nest the welding fixture on the outside of the ESC ceramic disk to fix the ESC ceramic disk and form a welding pool at the same time. Indium-based brazing filler metal into the weld pool, and the weld pool is subjected to a second ultrasonic immersion at an ultrasonic frequency of 20 kHz for 30 minutes. Then, the metal base is fastened and assembled and pressure is applied using a force-applying object weighing 20 kg. After the fastening assembly, a gap of 0.3 mm is left between the welding fixture and the ESC ceramic disk and the metal base, and the concentricity of the ESC ceramic disk and the metal base is 0.3 mm. The welding fixture is in the shape of a double ring, including a ceramic disk fixing ring and a base fixing ring that are fixedly arranged; the inner diameter of the ceramic disk fixing ring is larger than the inner diameter of the base fixing ring; and the part of the base fixing ring that protrudes from the ceramic disk fixing ring is used to shield the area of ​​the welding surface edge of the ESC ceramic disk that does not need to contact the solder. The metal base 4 has a plurality of weld layer support columns 5 uniformly fixedly arranged on its welding surface, and the height of the weld layer support columns 5 is the same and equal to the thickness of the brazing solder layer. (4) Cooling and forming: After cooling, the welding fixture is removed to obtain the electrostatic chuck formed by brazing.

[0047] Example 3 This embodiment provides a brazing method for an electrostatic chuck, the brazing method comprising the following steps: (1) Pretreatment of ESC ceramic disk: The area on the edge of the ceramic disk that does not need to contact the solder is masked with protective tape; then the welding surface of the ESC ceramic disk is sandblasted with 60-mesh sand to make the roughness of the welding surface of the ESC ceramic disk 5μm. (2) Ultrasonic wetting of the welding surface: The ESC ceramic disk and metal base after the pretreatment in step (1) are placed on the heating table and heated to 240°C at a heating rate of 3°C / min. Then, tin-based brazing solder is laid on the welding surface of the ESC ceramic disk and metal base for ultrasonic wetting. The ultrasonic immersion time is 40 minutes and the ultrasonic frequency is 30 kHz. (3) Assembly and brazing: Under the condition of maintaining a temperature of 240°C, prepare the welding base and place the ESC ceramic disk, and then nest the welding fixture on the outside of the ESC ceramic disk to fix the ESC ceramic disk and form a welding pool at the same time. The molten pool is filled with tin-based brazing filler, and the molten pool is subjected to a second ultrasonic immersion at an ultrasonic frequency of 30 kHz for 20 minutes. Then the metal base is fastened and assembled and pressure is applied using a force-applying object weighing 30 kg. After the fastening assembly, a gap of 0.5 mm is left between the welding fixture and the ESC ceramic disk and the metal base, and the concentricity of the ESC ceramic disk and the metal base is 0.45 mm. The welding fixture is in the shape of a double ring, including a ceramic disk fixing ring and a base fixing ring that are fixedly arranged; the inner diameter of the ceramic disk fixing ring is larger than the inner diameter of the base fixing ring; and the part of the base fixing ring that protrudes from the ceramic disk fixing ring is used to shield the area of ​​the welding surface edge of the ESC ceramic disk that does not need to contact the solder. The metal base has several weld layer support columns uniformly and fixedly arranged on its welding surface, and the height of the weld layer support columns is the same and equal to the thickness of the brazing solder layer. (4) Cooling and forming: After cooling, the welding fixture is removed to obtain the electrostatic chuck formed by brazing.

[0048] Example 4 This embodiment provides a brazing method for an electrostatic chuck, the only difference between this brazing method and Embodiment 1 is that: This embodiment omits the second ultrasonic wetting process of the weld pool.

[0049] Example 5 This embodiment provides a brazing method for an electrostatic chuck, the only difference between this brazing method and Embodiment 1 is that: In this embodiment, the roughness of the ESC ceramic disk welding surface after sandblasting in step (1) is adjusted to 3μm.

[0050] Example 6 This embodiment provides a brazing method for an electrostatic chuck, the only difference between this brazing method and Embodiment 1 is that: In this embodiment, the roughness of the ESC ceramic disk welding surface after sandblasting in step (1) is adjusted to 10μm.

[0051] Example 7 This embodiment provides a brazing method for an electrostatic chuck, the only difference between this brazing method and Embodiment 1 is that: In this embodiment, the heating rate described in step (2) is adjusted to 5℃ / min.

[0052] Example 8 This embodiment provides a brazing method for an electrostatic chuck, the only difference between this brazing method and Embodiment 1 is that: In this embodiment, the brazing temperature is adjusted to 200℃.

[0053] Example 9 This embodiment provides a brazing method for an electrostatic chuck, the only difference between this brazing method and Embodiment 1 is that: In this embodiment, the brazing temperature is adjusted to 260℃.

[0054] Example 10 This embodiment provides a brazing method for an electrostatic chuck, the only difference between this brazing method and Embodiment 1 is that: In this embodiment, the weight of the object used in the pressurization process described in step (3) is adjusted to 10 kg.

[0055] Example 11 This embodiment provides a brazing method for an electrostatic chuck, the only difference between this brazing method and Embodiment 1 is that: In this embodiment, the weight of the object used in the pressurization process described in step (3) is adjusted to 40 kg.

[0056] Example 12 This embodiment provides a brazing method for an electrostatic chuck, the only difference between this brazing method and Embodiment 1 is that: In this embodiment, the width of the gap between the welding fixture, the ESC ceramic disk, and the metal base is adjusted to 0mm.

[0057] Example 13 This embodiment provides a brazing method for an electrostatic chuck, the only difference between this brazing method and Embodiment 1 is that: In this embodiment, the width of the gap between the welding fixture, the ESC ceramic disk, and the metal base is adjusted to 0.8 mm.

[0058] Comparative Example 1 This comparative example provides a brazing method for an electrostatic chuck, the only difference between this brazing method and Example 1 is that: This comparative example omits the use of welding fixtures.

[0059] Comparative Example 2 This comparative example provides a brazing method for an electrostatic chuck, the only difference between this brazing method and Example 1 is that: This comparative example omits the sandblasting process described in step (1).

[0060] Detection: The electrostatic chucks provided in the above embodiments and comparative examples were tested, and the results are shown in Table 1. The inspection includes welding pass rate inspection and flatness inspection of the upper surface of the metal base; The welding qualification rate is tested using an ultrasonic C-scan flaw detector.

[0061] Table 1 According to Table 1, the following points can be observed: (1) Comprehensive analysis of Examples 1-3 shows that the electrostatic chuck obtained by the brazing method provided by the present invention has excellent flatness (<0.35mm), which further improves the adsorption stability of the product and increases its service life; In addition, the brazing method provided by this invention can further improve the welding qualification rate of products, and the process is simple, the cost is lower, and the welding dimensions are accurate. A comprehensive analysis of Examples 1, 5-6 and Comparative Example 2 shows that the sandblasting treatment can optimize the roughness of the ceramic disc welding surface, thereby improving the welding qualification rate of the product. If the roughness of the ceramic disk welding surface is too low, the surface of the ceramic disk will be difficult to be wetted by the solder, affecting the welding qualification rate. If it is too high, the micro-surface of the ceramic disk will have large undulations, and the low points will not be wetted by the solder, reducing the welding qualification rate. Example 4 omits the second ultrasonic wetting process of the weld pool, resulting in insufficient wetting of the weld surface and affecting the weld bonding rate; Example 7 has an excessively high heating rate during the heating process, which can cause product deformation or cracking and affect the flatness after welding; Example 8 has a low brazing temperature, which can lead to poor solder fluidity and poor wetting effect; Example 9 has a high brazing temperature, which can cause the solder to oxidize easily; Example 10 has a low pressure during the pressure treatment, which can lead to poor flatness after welding; Example 11 has a high pressure during the pressure treatment, which can cause solder to overflow and affect the weld bonding rate. Analysis of Examples 12-13 shows that if the gap width between the fixture and the sample to be welded is too low, it will cause difficulty in fastening the metal base and affect the flatness after welding; if it is too high, it will cause welding eccentricity and affect the welding bonding rate. Analysis of Comparative Example 1 shows that omitting the use of welding fixtures will lead to welding eccentricity and affect the welding bonding rate.

[0062] For electrostatic chucks with an ESC ceramic disc area larger than the metal base, this invention can significantly improve the bonding rate and success rate of electrostatic chuck welding by adding welding fixtures and improving the welding process. Moreover, the process is simple, the cost is lower, and the welding dimensions are accurate.

[0063] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A brazing method for an electrostatic chuck, characterized in that, The electrostatic chuck includes an ESC ceramic disk and a metal base, wherein the diameter of the ESC ceramic disk is greater than the diameter of the metal base. The brazing method includes the following steps: (1) Pretreatment of ESC ceramic disk: The welding surface of the ESC ceramic disk is sandblasted. (2) Ultrasonic impregnation of the welding surface: The ESC ceramic disk and the metal base after the pretreatment in step (1) are heated and then the welding surface is ultrasonically impregnated. (3) Assembly and brazing: Prepare the welding base and place the ESC ceramic disk, and then nest the welding fixture on the outside of the ESC ceramic disk to fix the ESC ceramic disk and form a welding pool at the same time. Fill the weld pool with solder, then fasten and assemble the metal base and apply pressure. (4) Cooling and forming: After cooling, the welding fixture is removed to obtain the electrostatic chuck formed by brazing.

2. The brazing method according to claim 1, characterized in that, The particle size of the sand used in the sandblasting process in step (1) is 30~60 mesh; Preferably, the roughness of the welding surface of the ESC ceramic disk after sandblasting in step (1) is 5~8μm.

3. The brazing method according to claim 1 or 2, characterized in that, The heating rate of the heating treatment in step (2) is 2~3℃ / min; Preferably, the final temperature of the heat treatment in step (2) is 220~240℃.

4. The brazing method according to any one of claims 1-3, characterized in that, The wetting medium used in step (2) for ultrasonic wetting is molten brazing solder; Preferably, the brazing solder melt includes tin-based solder or indium-based solder; Preferably, the ultrasonic immersion time in step (2) is 25~40 min; Preferably, the ultrasonic frequency of the ultrasonic immersion in step (2) is 30~50kHz.

5. The brazing method according to any one of claims 1-4, characterized in that, After the snap-fit ​​assembly described in step (3), the concentricity of the ESC ceramic disk and the metal base is <0.5mm; Preferably, after the snap-fit ​​assembly in step (3), a gap is left between the welding fixture and the ESC ceramic disk and the metal base; Preferably, the width of the gap is 0.3~0.5mm.

6. The brazing method according to any one of claims 1-5, characterized in that, Step (3) before the fastening assembly also includes a second ultrasonic impregnation of the welding pool; Preferably, the immersion time of the second ultrasonic immersion is 20-30 minutes; Preferably, the immersion temperature of the second ultrasonic immersion is 220~240℃; Preferably, the ultrasonic frequency of the second ultrasonic immersion is 30~50kHz.

7. The brazing method according to any one of claims 1-6, characterized in that, The metal base has several welded layer support columns uniformly and fixedly arranged on its welding surface. Preferably, the height of the welded layer support columns is the same and equal to the thickness of the brazing solder layer.

8. The brazing method according to any one of claims 1-7, characterized in that, The pressurization process in step (3) includes: placing a force-applying object on the non-welded surface of the metal base; Preferably, the weight of the object applying the force is 20-30 kg.

9. The brazing method according to claim 8, characterized in that, The flatness of the metal base after pressure treatment is <0.5mm.

10. The brazing method according to claim 5, characterized in that, The welding fixture is made of aluminum alloy; Preferably, the welding base is made of aluminum alloy.

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