Electrostatic chuck with optimized edge seal and method of making the same

Abstract

The application discloses an electrostatic chuck with optimized edge sealing performance and a preparation method thereof, and belongs to the technical field of electrostatic chucks. The working surface of the electrostatic chuck comprises an edge sealing area and an intermediate working area located in the edge sealing area. The Ra value of the intermediate working area is 1-2 times the Ra value of the edge sealing area. The preparation method of the electrostatic chuck comprises the following steps: step 1, preparing an electrostatic chuck base; step 2, preparing a laminated body; step 3, glue removal sintering; step 4, machining and grinding the sintered body and assembling the sintered body on the electrostatic chuck base; and step 5, processing the intermediate working area. The edge sealing area of the working surface of the sintered body is covered, and the intermediate working area is subjected to sand blasting treatment, so that the Ra value of the intermediate working area is controlled to be 1-2 times the Ra value of the edge sealing area.

Description

Technical Field

[0001] This invention relates to the field of electrostatic chuck technology, and in particular to an electrostatic chuck with optimized edge sealing and its preparation method. Background Technology

[0002] In existing technical solutions, helium leakage is a very important control point for electrostatic chucks. Most existing electrostatic chucks prevent helium leakage by controlling the height of the dielectric layer edge.

[0003] The main drawback is that the roughness and height of the edges are made under conditions where no adsorption force is generated. In the actual process, as the usage time increases, the contamination and corrosion of the dielectric layer surface will increase the edge leakage rate. Especially in JR type electrostatic chucks, the increase in leakage rate may mean a decrease in adsorption force, causing abnormalities in the process. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an electrostatic chuck with optimized edge sealing and its preparation method, thereby improving the overall sealing performance of helium, reducing helium leakage rate, and improving the working stability and service life of the electrostatic chuck.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] One aspect of this invention discloses an electrostatic chuck with optimized edge sealing performance. The working surface of the electrostatic chuck includes an edge sealing region and an intermediate working region located within the edge sealing region. The Ra value of the intermediate working region is 1 to 2 times that of the Ra value of the edge sealing region.

[0007] Another aspect of the present invention discloses an electrostatic chuck with optimized edge sealing performance and a method for preparing the same, the method comprising the following steps:

[0008] Step 1: Prepare the electrostatic chuck base

[0009] The electrostatic chuck base is manufactured using machining methods;

[0010] Step 2: Preparation of the laminate

[0011] The prepared material includes alumina powder and dopant that can reduce the volume resistivity after sintering. The dopant, which is chromium oxide or manganese oxide, is added to the alumina powder at an amount of 0.4% to 0.8%. The dispersant, alumina powder, dopant, high-purity alumina milling beads and solvent are added in a first ball milling process for 45 to 55 hours. After the first ball milling, plasticizer and binder are added for premixing for 20 to 28 hours. After mixing, the mixture is ball milled again for 24 to 48 hours to ensure that the contents are fully mixed. The resulting ceramic slurry is cast and printed using electrode metal materials, and then laminated to obtain a laminate.

[0012] Step 3: Debinding and Sintering

[0013] The above-mentioned laminated body was debinded and sintered to obtain a sintered body with a uniform color and a volume resistivity of 1×10⁻⁶. 9 ~1×10 11 Ω·cm;

[0014] Step 4: Electrostatic chuck assembly

[0015] The sintered body is machined and ground, and then assembled onto an electrostatic chuck base. After assembly, grinding and polishing are continued to ensure the flatness and morphology of the overall dielectric layer and to determine the Ra value of the edge.

[0016] Step 5: Process the intermediate working area

[0017] The edge sealing area of ​​the sintered body working surface is covered, and the middle working area is sandblasted. The hardness of the sandblasting material is required to be greater than or equal to that of alumina ceramic. The sandblasting pressure is 0.30-0.50 MPa, the nozzle spray angle is 60-90°, the distance between the nozzle and the treated surface is 10-12 cm, and the sandblasting time is 5-30 seconds. This controls the Ra value of the middle working area to be 1-2 times that of the edge sealing area.

[0018] Preferably, in step 2, the solvent is any one of ethanol, toluene, and xylene.

[0019] Preferably, in step 2, the electrode metal material is any one of W, Mo, and Ti.

[0020] Preferably, in step 5, the sandblasting material is corundum sand or diamond sand.

[0021] The above technical solution has the following beneficial effects:

[0022] This application improves the overall helium sealing performance under ESC operating conditions by differentiating the surface roughness of the electrostatic chuck through different adsorption forces, thereby reducing helium leakage and improving the working stability and service life of the electrostatic chuck. Detailed Implementation

[0023] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, 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.

[0024] An electrostatic chuck with optimized edge sealing and its preparation method are disclosed. Specifically, the electrostatic chuck may be a JR electrostatic chuck. The preparation method includes the following steps:

[0025] Step 1: Prepare the electrostatic chuck base

[0026] The electrostatic chuck base is manufactured by machining. Specifically, the electrostatic chuck base can be made of aluminum and machined into a disc shape.

[0027] Step 2: Preparation of the laminate

[0028] The prepared material includes alumina powder and dopant that can reduce the volume resistivity after sintering. The dopant, which is chromium oxide or manganese oxide, is added to the alumina powder at an amount of 0.4% to 0.8%. The dispersant, alumina powder, dopant, high-purity alumina milling beads and solvent are added in a first ball milling process for 45 to 55 hours. After the first ball milling, plasticizer and binder are added for premixing for 20 to 28 hours. After mixing, the mixture is ball milled again for 24 to 48 hours to ensure that the contents are fully mixed. The resulting ceramic slurry is cast and printed using electrode metal materials, and then laminated to obtain a laminate.

[0029] Specifically, the laminate is made of alumina powder and dopant. The dopant, which reduces the volume resistivity after sintering, is chromium oxide or manganese oxide, added at 0.4% to 0.8% of the total powder weight. The addition of a dispersant, alumina powder, dopant, high-purity alumina grinding beads, and solvent is followed by a single ball milling process for 45 hours, 55 hours, or 50 hours. The solvent is any one of ethanol, toluene, or xylene, and the dispersant can be polyethylene. Pyrrolidone is ball-milled once, and then a plasticizer and binder are added for premixing. The premixing time is 20h, 28h, or 24h. The plasticizer can be dibutyl phthalate, and the binder can be polyvinyl butyral. After premixing, the mixture is ball-milled for 24h, 48h, or 36h to ensure that the contents are fully mixed. The resulting ceramic slurry is then cast and printed using electrode metal materials, and then laminated to obtain a laminate. The electrode metal material can be any one of W, Mo, or Ti.

[0030] Step 3: Debinding and Sintering

[0031] The above-mentioned laminated body was debinded and sintered to obtain a sintered body with a uniform color and a volume resistivity of 1×10⁻⁶. 9 ~1×10 11 Ω·cm; Specifically, the above-mentioned laminated body is placed in a debinding furnace and heated to remove the binder, specifically to 600 degrees Celsius. After debinding, it is placed in a sintering furnace for sintering at a temperature of 1850–1900 degrees Celsius. After reaching the sintering temperature, it is held for 2–3 hours, then cooled to room temperature to complete the sintering. The sintered body has a uniform color and a volume resistivity of 1×10⁻⁶ Ω·cm. 9 ~1×10 11 Ω·cm;

[0032] Step 4: Electrostatic chuck assembly

[0033] The sintered body is machined and ground, and then assembled onto an electrostatic chuck base. After assembly, grinding and polishing are continued to ensure the flatness and morphology of the overall dielectric layer and to determine the Ra value of the edge.

[0034] Specifically, the sintered body is machined and ground, such as being machined into a disc-shaped structure, its surface is ground, and after processing it is bonded to an electrostatic chuck base. Then, it is ground and polished to ensure the flatness and morphology of the overall dielectric layer. The Ra value of the edge is determined as needed.

[0035] Step 5: Process the intermediate working area

[0036] The edge sealing area of ​​the sintered body working surface is covered, and the middle working area is sandblasted. The hardness of the sandblasting material is required to be greater than or equal to that of alumina ceramic. The sandblasting pressure is 0.30-0.50 MPa, the nozzle spray angle is 60-90°, the distance between the nozzle and the treated surface is 10-12 cm, and the sandblasting time is 5-30 seconds. This controls the Ra value of the middle working area to be 1-2 times that of the edge.

[0037] Specifically, the edge sealing area of ​​the sintered body's working surface is masked, for example, using alumina ceramic of a suitable shape. The edge sealing area can be the area around the edge of the working surface excluding the cooling gas groove. After masking the edge sealing area, the remaining part is sandblasted, that is, the middle working area is sandblasted to make the surface roughness Ra value of the middle working area greater than that of the masked edge sealing area. The sandblasting pressure can be 0.30 MPa, 0.50 MPa, or 0.4 MPa. The spray angle of the sandblasting nozzle is 60-90°, specifically the acute angle formed with the surface of the middle working area. It can be 60 degrees, 90 degrees, 70 degrees, or 80 degrees. The distance between the nozzle and the treated surface is between 10-12 cm. The sandblasting time is 5 seconds, 30 seconds, 15 seconds, or 20 seconds. After sandblasting, the Ra value of the middle working area is 1, 2, or 1.5 times that of the edge sealing area.

[0038] The purpose of this application is to differentiate the adsorption forces between the edge sealing area and the middle working area by controlling the roughness and morphology distribution of the dielectric layer of the electrostatic chuck, making the adsorption force of the edge sealing area higher than that of the middle working area, so that helium is less likely to leak from the ceramic edge gas path of the electrostatic chuck into the cavity, thereby ensuring the stability of the process.

[0039] The basic concept of this application is that the JR type electrostatic chuck is characterized by the ability of the dielectric layer to conduct electrons like a conductor after an electric field is generated, thereby concentrating the charge on the surface of the dielectric layer. This characteristic means that, under the same material conditions, the adsorption force of this type of electrostatic chuck is mainly affected by the gap width between the surface and the wafer. The smaller the gap, the greater the adsorption force. Furthermore, since the thickness of the dielectric layer is much greater than the gap value, the adsorption force of the JR type electrostatic chuck is much greater than that of the Coulomb type under the same voltage. The size of the gap value can be controlled by the roughness and surface morphology.

[0040] By utilizing this characteristic, the Ra value of the intermediate working area is increased. Through the difference in adsorption force, more helium is contained in the intermediate working area when the electrostatic chuck is working, thereby improving the sealing performance of the electrostatic chuck structure itself for helium and reducing the impact caused by later use and contamination.

[0041] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. An electrostatic chuck with optimized edge sealing, characterized in that, The working surface of the electrostatic chuck includes an edge sealing area and a middle working area located in the edge sealing area, wherein the Ra value of the middle working area is 1 to 2 times that of the edge sealing area.

2. A method for preparing an electrostatic chuck with optimized edge sealing as described in claim 1, characterized in that, The preparation method includes the following steps: Step 1: Prepare the electrostatic chuck base The electrostatic chuck base is manufactured using machining methods; Step 2: Preparation of the laminate The prepared material includes alumina powder and dopant that can reduce the volume resistivity after sintering. The dopant, which is chromium oxide or manganese oxide, is added to the alumina powder at an amount of 0.4% to 0.8%. The dispersant, alumina powder, dopant, high-purity alumina milling beads and solvent are added in a first ball milling process for 45 to 55 hours. After the first ball milling, plasticizer and binder are added for premixing for 20 to 28 hours. After mixing, the mixture is ball milled again for 24 to 48 hours to ensure that the contents are fully mixed. The resulting ceramic slurry is cast and printed using electrode metal materials, and then laminated to obtain a laminate. Step 3: Debinding and Sintering The above-mentioned laminated body was debinded and sintered to obtain a sintered body with a uniform color and a volume resistivity of 1×10⁻⁶. 9 ~1×10 11 Ω·cm; Step 4: Electrostatic chuck assembly The sintered body is machined and ground, and then assembled onto an electrostatic chuck base. After assembly, grinding and polishing are continued to ensure the flatness and morphology of the overall dielectric layer and to determine the Ra value of the edge. Step 5: Process the intermediate working area The edge sealing area of ​​the sintered body working surface is covered, and the middle working area is sandblasted. The hardness of the sandblasting material is required to be greater than or equal to that of alumina ceramic. The sandblasting pressure is 0.30-0.50 MPa, the nozzle spray angle is 60-90°, the distance between the nozzle and the treated surface is 10-12 cm, and the sandblasting time is 5-30 seconds. This controls the Ra value of the middle working area to be 1-2 times that of the edge sealing area.

3. The method for preparing an electrostatic chuck with optimized edge sealing according to claim 2, characterized in that, In step 2, the solvent is any one of ethanol, toluene, and xylene.

4. The method for preparing an electrostatic chuck with optimized edge sealing according to claim 2, characterized in that, In step 2, the electrode metal material is any one of W, Mo, and Ti.

5. The method for preparing an electrostatic chuck with optimized edge sealing according to claim 2, characterized in that, In step 5, the sandblasting material is corundum sand or diamond sand.