Preparation method of electrostatic chuck

Abstract

The invention discloses a preparation method of an electrostatic chuck, and belongs to the technical field of electrostatic chucks, and the preparation method comprises the following steps: preparing an electrostatic chuck base by adopting a machining mode; manufacturing a ceramic plate with an electrode material; the ceramic plate is subjected to circle cutting, punching, parallelism grinding, planeness grinding and polishing through a ceramic CNC, a polishing machine and a grinding machine, and the ceramic plate is machined; the ceramic plate and the metal base are bonded together through silicone glue; the connected electrostatic chuck is placed in a metal clamp for brazing in an inverted mode, active solder pieces for brazing are placed in the electrode holes, and after vacuum brazing is completed, the metal clamp is loosened, and the electrostatic chuck is taken out; and the welded electrostatic chuck is subjected to polishing, sand blasting and other treatment, and preparation of the electrostatic chuck is completed. According to the technical scheme, the active welding flux is used, so that binding force can be generated between the electrode terminal and the electrode layer and between the electrode terminal and the electrode hole wall, and the firmness of a welding part is greatly enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of electrostatic chucks, and in particular to a method for preparing an electrostatic chuck. Background Art

[0002] In the prior art, most electrostatic chucks are electroplated or chemically plated before welding the electrode terminals to the electrode holes, so that a tight coating is formed on the surface of the electrode holes as a connection between the electrode layer and the solder. This is done to improve the firmness of welding, but it is extremely dependent on the quality of the coating. If bubbles or impurities are mixed in during the formation of the coating, the possibility of arcing will be greatly increased. The welding process is carried out in a vacuum state, so the possibility of bubbles is almost non-existent, which is obviously more controllable than electroplating and chemical plating. In addition, the waste liquid generated by electroplating and chemical plating will cause serious pollution to the environment and is not suitable for long-term and large-scale promotion and use. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for preparing an electrostatic chuck, solve the problems raised in the background technology, and improve the welding firmness of the electrode terminal.

[0004] In order to solve the above technical problems, the technical solution of the present invention is:

[0005] A method for preparing an electrostatic chuck, the method comprising:

[0006] S1: Prepare the electrostatic chuck base by machining;

[0007] S2: making a ceramic plate with electrode material;

[0008] S3: CNC machine, polishing machine and grinder are used to cut the ceramic plate into a circle, punch holes, grind parallelism, grind flatness and polish it, and process the ceramic plate into a product that meets the standards;

[0009] S4: Use silicone glue to bond the ceramic plate to the metal base;

[0010] S5: Place the connected electrostatic chuck upside down in a metal fixture for brazing, place an active solder sheet for brazing in the electrode hole, wherein the material of the active solder sheet includes Ag, Cu, and Ti, wherein the Ag content is 60-75%, the Cu content is 25%-40%, and the Ti content is 1-2%, fix the electrode terminal on the top of the active solder sheet through the fixture, and perform vacuum brazing at a temperature of 650-900°C in an environment with a vacuum degree not less than E-03Pa. After the welding is completed, release the metal fixture and take out the electrostatic chuck;

[0011] S6: polishing, sandblasting and other treatments are performed on the welded electrostatic chuck to complete the preparation of the electrostatic chuck.

[0012] Preferably, the material of the active solder sheet also includes In. When the material of the active solder sheet includes In, the Ag content is 50-70%, the Cu content is 20%-40%, the Ti content is 1-2%, and the In content is 10-15%. The electrode terminal is fixed on the top of the active solder sheet by a clamp, and vacuum brazing is performed at a temperature of 600-750°C in an environment with a vacuum degree not lower than E-03Pa. After the vacuum brazing is completed, the metal clamp is released and the electrostatic chuck is taken out.

[0013] Preferably, the metal clamp includes a base plate for placing the electrostatic chuck, a clamping plate is provided above the base plate, the clamping plate and the base plate are connected by a plurality of support rods, the clamping plate and the support rods are detachably connected, a plurality of through holes are provided on the clamping plate for cooperating with positioning pins, the bottom of the positioning pins cooperates with the positioning holes on the electrostatic chuck, a pressure plate is provided on the top of the positioning pins, the bottom of the electrode terminal cooperates with the electrode hole of the electrostatic chuck, an active solder sheet is provided in the electrode hole, and an electrode terminal positioning hole cooperating with the top of the electrode terminal is provided on the clamping plate.

[0014] Preferably, the electrode material is any one of tungsten, molybdenum, titanium, platinum and palladium.

[0015] Preferably, the ceramic plate is alumina ceramic, aluminum nitride ceramic, or silicon carbide ceramic.

[0016] The above technical solution has the following beneficial effects:

[0017] By using activated solder, the electrode terminal can generate bonding force with the electrode layer and the electrode hole wall, which greatly enhances the firmness of the welding part. Compared with the electroplating or chemical plating methods in the prior art, it is more environmentally friendly, the connection between the electrode and the terminal is more stable, and it is not easy to cause arc breakdown due to bubbles or impurities mixed in during the processing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the metal clamp of the present invention;

[0019] Figure 2 It is a schematic cross-sectional structure diagram of the metal clamp of the present invention. DETAILED DESCRIPTION

[0020] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0021] The basic concept of the present application is: prepare a ceramic plate, the main material of the ceramic plate is alumina ceramic, aluminum nitride ceramic, silicon carbide ceramic, or other ceramics, the electrode material includes but is not limited to tungsten, molybdenum, titanium, platinum, palladium, the sintered ceramic plate is surface ground and punched, and then the processed ceramic plate is connected to the processed metal base, and the electrode terminal is vacuum brazed on the electrode hole with an active solder sheet, the main component of the material of the active solder sheet is conventional welding materials such as Ag and Cu, and the activation auxiliary material is a low-melting-point welding material such as Ti and In, wherein the content of Ti does not exceed 2%, and if In is added, the content of In is not less than 10% but not more than 15%;

[0022] The purpose of the present application is to firmly combine the electrode hole and the electrode terminal by using active solder that can directly connect metal and ceramic without additional electroplating. On the surface, welding the electrode terminal and the electrode layer is welding between metal and metal; but in fact, the electrode layer of only tens of microns cannot provide sufficient bonding force after sintering, and is easy to fall off from the ceramic layer, while the active solder can provide an additional bonding force with the electrode hole wall, which can greatly improve the bonding strength between the electrode terminal and the electrostatic chuck;

[0023] A method for preparing an electrostatic chuck, the method comprising:

[0024] S1: Prepare the electrostatic chuck base by machining;

[0025] S2: Making a ceramic plate with electrode material, the ceramic plate is alumina ceramic, aluminum nitride ceramic or silicon carbide ceramic, which is selected according to actual conditions;

[0026] S3: Ceramic plates are cut into circles, punched, ground for parallelism, ground for flatness, and polished by ceramic CNC, polishing machines, and processed into standard products, so that the flatness, surface quality and other parameters of the ceramic plates meet the design requirements;

[0027] S4: Use silicone glue to bond the ceramic plate to the metal base, completing the connection between the ceramic plate and the electrostatic chuck base;

[0028] S5: Place the connected electrostatic chuck upside down in a metal fixture for brazing, place an active solder sheet for brazing in the electrode hole, wherein the material of the active solder sheet includes Ag, Cu, and Ti, wherein the Ag content is 60-75%, the Cu content is 25%-40%, and the Ti content is 1-2%, and the electrode terminal is fixed on the top of the active solder sheet through the fixture, and vacuum brazing is performed at a temperature of 650-900°C in an environment where the vacuum degree is not less than E-03Pa. After the welding is completed, the metal fixture is released and the electrostatic chuck is taken out;

[0029] In some embodiments, the material of the active solder sheet includes Ag, Cu, and Ti, wherein the Ag content accounts for 60% or 75%, the Cu content accounts for 25% or 40%, and the Ti content accounts for 1% or 2%. The electrode terminal is fixed on the top of the active solder sheet by a clamp, and then vacuum brazing is performed at a temperature of 650°C or 900°C in an environment where the vacuum degree is not less than E-03Pa. After the welding is completed, the metal clamp is released and the electrostatic chuck is taken out;

[0030] In some other embodiments, the material of the active solder sheet includes Ag, Cu, and Ti, wherein the Ag content accounts for 60%, the Cu content accounts for 39%, the Ti content accounts for 1%, and the total proportion is 100%, or the Ag content in the active solder sheet accounts for 70%, the Cu content accounts for 29%, and the Ti content accounts for 2%. In an environment where the vacuum degree is not less than E-03Pa, vacuum brazing is performed at a temperature of 650°C or 900°C. After the welding is completed, the metal clamp is released and the electrostatic chuck is removed;

[0031] S6: polishing, sandblasting, etc. the welded electrostatic chuck to complete the preparation of the electrostatic chuck;

[0032] In some embodiments, the material of the active solder sheet further includes In. When the material of the active solder sheet includes In, the Ag content is 50-70%, the Cu content is 20%-40%, the Ti content is 1-2%, and the In content is 10-15%. The electrode terminal is fixed on the top of the active solder sheet by a clamp, and vacuum brazing is performed at a temperature of 600-750° C. in an environment where the vacuum degree is not less than E-03Pa. After the vacuum brazing is completed, the metal clamp is released and the electrostatic chuck is taken out;

[0033] In some other embodiments, the material of the active solder sheet further includes In. When the material of the active solder sheet includes In, the Ag content is 50% or 70%, the Cu content is 20% or 40%, the Ti content is 1 or 2%, and the In content is 10% or 15%, and the total ratio is less than or equal to 100%. The electrode terminal is fixed on the top of the active solder sheet by a clamp, and vacuum brazing is performed at a temperature of 600° C. or 750° C. in an environment where the vacuum degree is not less than E-03Pa. After the vacuum brazing is completed, the metal clamp is released and the electrostatic chuck is taken out;

[0034] Alternatively, when the material of the active solder sheet includes In, the Ag content is 6%, the Cu content is 23%, the Ti content is 2%, the In content is 15%, and the total ratio is less than or equal to 100%, the electrode terminal is fixed on the top of the active solder sheet by a clamp, and vacuum brazing is performed at a temperature of 600°C or 750°C in an environment with a vacuum degree not less than E-03Pa;

[0035] refer to Figure 1 , Figure 2 The metal fixture includes a base plate 2 for placing an electrostatic chuck, a clamping plate 3 is provided above the base plate 2, and the clamping plate 3 is connected to the base plate 2 through a plurality of support rods 5, such as three support rods 5, which are evenly arranged in the circumferential direction, and the clamping plate 3 is detachably connected to the support rods 5. For example, the bottom of the support rod 5 is fixedly connected to the base plate 2, and a groove cooperating with the support rod 5 is provided on the bottom side of the clamping plate 3. A plurality of through holes cooperating with the positioning pins 6 are provided on the clamping plate 3, and the bottom of the positioning pins 6 cooperates with the positioning holes on the electrostatic chuck. The electrostatic chuck is positioned by setting the positioning pins 6 to To facilitate the next step of welding, a pressing plate 4 is provided on the top of the positioning pin 6, and the pressing plate 4 is used to press the positioning pin 6 to keep the positioning pin 6 stable. The bottom of the electrode terminal 7 cooperates with the electrode hole 9 of the electrostatic chuck 1, and an active solder sheet 8 is provided in the electrode hole 9. The clamping plate 3 is provided with an electrode terminal positioning hole that cooperates with the top of the electrode terminal 7. Before vacuum brazing, after the electrode terminal 7 is installed, the top is pressed by the pressing plate 4, and the clamping plate 3 cooperates with the electrode terminal 7 to ensure the stability and reliability of the electrode terminal 7, and ensure the correct position after vacuum brazing;

[0036] The electrode material is any one of tungsten, molybdenum, titanium, platinum and palladium, which is selected according to the actual situation;

[0037] The technical solution of the present application has the following advantages over the prior art: by using activated solder, the electrode terminal can generate bonding force with the electrode layer and the electrode hole wall, which greatly enhances the firmness of the welding part; and compared with the electroplating or chemical plating method, it is more environmentally friendly, the connection between the electrode and the terminal is more stable, and it is less likely to cause arc breakdown due to bubbles or impurities mixed in during the processing process.

[0038] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the scope of protection of the present invention.

Claims

1. A method for preparing an electrostatic chuck, characterized in that: The method comprises: S1: Prepare the electrostatic chuck base by machining; S2: making a ceramic plate with electrode material; S3: CNC machine, polishing machine and grinder are used to cut the ceramic plate into a circle, punch holes, grind parallelism, grind flatness and polish it, and process the ceramic plate into a product that meets the standards; S4: Use silicone glue to bond the ceramic plate to the metal base; S5: Place the connected electrostatic chuck upside down in a metal fixture for brazing, place an active solder sheet for brazing in the electrode hole, wherein the material of the active solder sheet includes Ag, Cu, and Ti, wherein the Ag content is 60-75%, the Cu content is 25%-40%, and the Ti content is 1-2%, and the electrode terminal is fixed on the top of the active solder sheet through the fixture, and vacuum brazing is performed at a temperature of 650-900°C in an environment where the vacuum degree is not less than E-03Pa. After the welding is completed, the metal fixture is released and the electrostatic chuck is taken out; S6: polishing, sandblasting and other treatments are performed on the welded electrostatic chuck to complete the preparation of the electrostatic chuck.

2. The method for preparing an electrostatic chuck according to claim 1, characterized in that: The material of the active solder sheet also includes In. When the material of the active solder sheet includes In, the Ag content is 50-70%, the Cu content is 20%-40%, the Ti content is 1-2%, and the In content is 10-15%. The electrode terminal is fixed on the top of the active solder sheet by a clamp, and vacuum brazing is performed at a temperature of 600-750°C in an environment with a vacuum degree not lower than E-03Pa. After the vacuum brazing is completed, the metal clamp is released and the electrostatic chuck is taken out.

3. The method for preparing an electrostatic chuck according to claim 1, characterized in that: The metal clamp includes a base plate for placing an electrostatic chuck, a clamping plate is provided above the base plate, the clamping plate and the base plate are connected by a plurality of support rods, the clamping plate and the support rods are detachably connected, a plurality of through holes are provided on the clamping plate for cooperating with positioning pins, the bottom of the positioning pins cooperates with the positioning holes on the electrostatic chuck, a pressure plate is provided on the top of the positioning pins, the bottom of the electrode terminal cooperates with the electrode hole of the electrostatic chuck, an active solder sheet is provided in the electrode hole, and an electrode terminal positioning hole cooperating with the top of the electrode terminal is provided on the clamping plate.

4. The method for preparing an electrostatic chuck according to claim 1, characterized in that: The electrode material is any one of tungsten, molybdenum, titanium, platinum and palladium.

5. The method for preparing an electrostatic chuck according to claim 1, characterized in that: The ceramic plate is aluminum oxide ceramic, aluminum nitride ceramic or silicon carbide ceramic.

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