Electrostatic chuck helium hole anti-pollution processing method

Abstract

This invention discloses a processing method for preventing contamination of helium gas holes in an electrostatic chuck, belonging to the field of electrostatic chuck technology. The method includes: Step S1: Heating and sealing with melted wax. The assembled electrostatic chuck is placed on a heating platform and heated. Paraffin wax is evenly applied to all helium gas holes on the ceramic adsorption surface of the electrostatic chuck. The melted wax penetrates into the helium gas holes, filling them completely. Step S2: Cleaning residual wax from the ceramic surface of the electrostatic chuck. Step S3: Natural cooling and shaping. The sealed electrostatic chuck is cooled to room temperature, sealing the helium gas hole channels. Step S4: Surface grinding and polishing. The adsorption working surface is ground and polished. Step S5: First-stage overflow dewaxing and cleaning. The chuck is placed in a second-stage hot water bath for cleaning. Step S6: Second-stage overflow cleaning. The dewaxed electrostatic chuck is transferred to a second-stage hot water bath for further cleaning. Step S7: Rinsing and drying. The electrostatic chuck is rinsed thoroughly with high-purity hot water.

Description

Technical Field

[0001] This invention relates to the field of electrostatic chuck technology, and in particular to a processing method for preventing contamination of the helium gas holes in an electrostatic chuck. Background Technology

[0002] The ceramic disk surface of the electrostatic chuck has numerous micropores with a diameter of 0.1–0.5 mm. A helium channel is located below the pores of the ceramic disk, allowing helium to flow upwards and control the temperature of the silicon wafer. Existing ceramic disk structures have porous ceramic installed below the vent holes to buffer the helium flow, reduce the direct impact of helium on the wafer, and simultaneously ensure uniform airflow exchange.

[0003] The electrostatic chuck structure consists of an upper ceramic plate and a lower metal substrate. After assembly, the adsorption working surface needs to be ground to ensure flatness. During the grinding process, alumina powder, abrasive particles shed from the grinding wheel, and debris are generated. The powder can flow into the pores with the cutting fluid during processing, causing blockage of the porous ceramic inside the ceramic plate. The numerous dense pores on the porous ceramic are difficult to clean completely, resulting in uneven helium flow in the adsorption area of ​​the ceramic plate, or even no airflow in some pores. This leads to uneven local temperature distribution on the silicon wafer, reducing chip yield.

[0004] Existing cleaning methods, such as ultrasonic cleaning and rinsing the pores with pure water after processing, are time-consuming and difficult to clean, but they cannot completely remove the powder particles stuck inside the porous ceramics. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a processing method for preventing contamination of the helium gas hole of an electrostatic chuck, which can solve the problem of contamination inside the helium gas hole of the electrostatic chuck.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0007] A method for preventing contamination of the helium gas port of an electrostatic chuck, the method comprising:

[0008] Step S1: Heating and sealing the hole with melted wax

[0009] The assembled electrostatic chuck is placed on a heating platform. After setting the heating temperature, it is heated until the overall temperature of the electrostatic chuck is uniform and stable. Then, paraffin wax is evenly applied to all the helium pores on the adsorption surface of the ceramic plate of the electrostatic chuck. The residual heat of the electrostatic chuck is used to completely melt the paraffin wax and allow it to naturally seep into the helium pores, filling them with liquid paraffin wax. The surface of the melted paraffin wax is flush with the surface of the ceramic plate of the electrostatic chuck. Each helium pore is checked to ensure that no pores are missed.

[0010] Step S2: Cleaning residual wax from the plate

[0011] After confirming that all helium gas holes are sealed, wipe the ceramic plate of the electrostatic chuck to remove excess paraffin wax around the helium gas holes and on the ceramic plate of the electrostatic chuck, leaving only the paraffin wax filling the helium gas holes to ensure that the working surface is flat and clean and to avoid surface residual wax interfering with subsequent grinding processes.

[0012] Step S3: Natural cooling and shaping

[0013] Remove the electrostatic chuck with the sealed hole from the heating platform and place it on a clean workbench to cool naturally to room temperature, allowing the paraffin inside the helium hole to completely solidify, forming a stable sealing structure and blocking the helium hole channel.

[0014] Step S4: Surface grinding and polishing

[0015] After cooling and shaping, the electrostatic chuck is clamped onto the grinding machine to grind and polish the adsorption working surface.

[0016] Step S5: Primary overflow dewaxing and cleaning

[0017] After grinding and polishing, the electrostatic chuck is placed in a hot water tank for cleaning. The tank is kept in a state of pure water overflow. Cleaning agent is added to the water. After the paraffin in the helium gas hole is completely melted by heat, it floats out of the tank with the overflowing pure water, keeping the water in the tank clean and removing the paraffin in the helium gas hole.

[0018] Step S6: Secondary overflow cleaning

[0019] After the electrostatic chuck has been dewaxed, it is transferred to a secondary hot water tank for further cleaning. The tank is kept overflowing with pure water to remove cleaning agent residue and trace impurities from the product surface and the inner walls of the micropores.

[0020] Step S7: Rinse and dry, then proceed to the next step.

[0021] After cleaning, the electrostatic chuck is rinsed thoroughly with high-purity hot water and then completely dried with clean nitrogen gas to complete the anti-contamination process for the helium gas holes of the electrostatic chuck.

[0022] Preferably, in step S1, the heating platform is heated to 80°C and the constant temperature heating time is at least 30 minutes to ensure that the electrostatic chuck temperature is uniform, the paraffin wax is fully melted, and the hole is fully filled.

[0023] Preferably, in step S4, water-based cutting fluid is used to grind and polish the adsorption working surface.

[0024] Preferably, in step S5, the water temperature in both the primary hot water tank and the secondary hot water tank is 70°C, and the cleaning time for each is at least 30 minutes.

[0025] The above technical solution has the following beneficial effects:

[0026] This invention employs a pre-grinding paraffin sealing process to completely seal all helium pores before finishing, preventing grinding powder, abrasive, and debris from entering the pores and interior of porous ceramics from the source. This completely solves the industry problem of dense pores in porous ceramics being prone to slag buildup and traditional cleaning methods being unable to thoroughly clean them, effectively preventing pore blockage.

[0027] The process involves sealing the holes with 80℃ constant-temperature wax melting and natural cooling at room temperature. The paraffin wax is evenly filled and has good sealing properties, making it suitable for microporous structures of 0.1mm to 0.5mm. Furthermore, the paraffin wax medium is non-corrosive and leaves no residue. It can be completely removed by subsequent low-temperature overflow cleaning without damaging the ceramic disc or porous ceramic structure, and without changing the original performance parameters of the product.

[0028] Strictly limit the use of water-based cutting fluid in the grinding process to avoid the combination of paraffin and oily media to form stubborn scale, greatly reduce the difficulty of dewaxing and cleaning, improve cleaning efficiency and cleanliness, and ensure the unobstructed and consistent pores.

[0029] The process employs a two-stage independent constant temperature overflow cleaning process, first removing wax and then cleaning, removing paraffin and cleaning agent residues in layers to ensure the cleanliness of the inside of the pores and the product surface. This effectively solves the problems of uneven helium flow and local gas interruption, significantly improving the temperature control uniformity of silicon wafers and significantly increasing chip production yield.

[0030] This invention features a simple process, controllable parameters, and strong stability. It eliminates the traditional time-consuming and inefficient post-processing cleaning steps, significantly shortens processing time, reduces rework costs, and is suitable for the standardized and mass production needs of electrostatic chucks. Detailed Implementation

[0031] 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.

[0032] A method for preventing contamination of the helium gas port of an electrostatic chuck, specifically including:

[0033] Step S1: Heating and sealing the hole with melted wax

[0034] Place the assembled electrostatic chuck on the heating platform, set the heating temperature and heating time, until the overall temperature of the electrostatic chuck is uniform and stable. Then, take natural paraffin wax and apply it evenly to all the helium pores on the adsorption surface of the ceramic plate of the electrostatic chuck. Use the residual heat of the electrostatic chuck to completely melt the paraffin wax and let it naturally seep into the helium pores, so that the helium pores are filled with liquid paraffin wax. The surface of the melted paraffin wax should be flush with the surface of the ceramic plate of the electrostatic chuck. Check each helium pore one by one to ensure that no helium pores are missed.

[0035] Specifically, the heating platform can be set to 80℃ and the constant temperature heating time can be 30 minutes to ensure that the electrostatic chuck temperature is uniform, the paraffin wax melts fully, and the hole is filled completely, thus eliminating the problems of incomplete sealing and leakage.

[0036] The process involves sealing the holes with 80℃ constant-temperature wax melting and natural cooling at room temperature. The paraffin wax is evenly filled and has good sealing properties, making it suitable for microporous structures of 0.1mm to 0.5mm. Furthermore, the paraffin wax medium is non-corrosive and leaves no residue. It can be completely removed by subsequent low-temperature overflow cleaning without damaging the ceramic disc or porous ceramic structure, and without changing the original performance parameters of the product.

[0037] Step S2: Cleaning residual wax from the plate

[0038] After confirming that all helium gas holes are sealed, gently wipe the ceramic plate of the electrostatic chuck with a lint-free paper to remove excess paraffin wax around the helium gas holes and on the ceramic plate of the electrostatic chuck, leaving only the paraffin wax filling the helium gas holes to ensure that the working surface is flat and clean and to avoid surface residual wax interfering with subsequent grinding processes.

[0039] Step S3: Natural cooling and shaping

[0040] Wearing heat-resistant gloves, remove the sealed electrostatic chuck from the heating platform and place it on a clean workbench to cool naturally to room temperature, allowing the paraffin inside the helium vent to completely solidify, forming a stable sealing structure and blocking the helium vent channel.

[0041] Step S4: Surface grinding and polishing

[0042] After cooling and solidification, the electrostatic chuck is clamped onto the grinding machine to grind and polish the adsorbed working surface. Water-based cutting fluid is used throughout the entire process, and oil-based cutting fluid is prohibited to avoid the oil medium from combining with paraffin to form stubborn scale, reduce the difficulty of subsequent wax removal and cleaning, and ensure thorough cleaning. In this step, since the helium pores are completely blocked by solid paraffin, impurities such as powder, particles, and debris generated during grinding cannot enter the pores and the internal porous ceramic structure, achieving full-process anti-contamination protection.

[0043] Strictly limit the use of water-based cutting fluid in the grinding process to avoid the combination of paraffin and oily media to form stubborn scale, greatly reduce the difficulty of dewaxing and cleaning, improve cleaning efficiency and cleanliness, and ensure the unobstructed and consistent pores.

[0044] Step S5: Primary overflow dewaxing and cleaning

[0045] After grinding and polishing, the electrostatic chuck is placed in the first-stage hot water tank for cleaning. The tank is kept in a state of pure water overflow. The water temperature in the first-stage hot water tank is 70℃. The cleaning time is at least 30 minutes. Henkel P3siliron HS cleaning agent is added to the water. After the paraffin in the helium gas vent is completely melted by the heat, it floats out of the tank with the overflowing pure water, keeping the water in the tank clean and removing the paraffin in the helium gas vent.

[0046] Step S6: Secondary overflow cleaning

[0047] Transfer the dewaxed electrostatic chuck to the secondary hot water tank for further cleaning. Keep the tank overflowing with pure water. The water temperature in the secondary hot water tank should be 70°C. Clean for at least 30 minutes, specifically 30 minutes, to remove residual cleaning agent and trace impurities from the product surface and the inner walls of the micropores.

[0048] The process employs a two-stage independent constant temperature overflow cleaning process, first removing wax and then cleaning, removing paraffin and cleaning agent residues in layers to ensure the cleanliness of the inside of the pores and the product surface. This effectively solves the problems of uneven helium flow and local gas interruption, significantly improving the temperature control uniformity of silicon wafers and significantly increasing chip production yield.

[0049] Step S7: Rinse and dry, then proceed to the next step.

[0050] After cleaning, the electrostatic chuck is rinsed thoroughly with high-purity hot water and then completely dried with clean nitrogen gas to complete the anti-contamination process for the helium gas holes of the electrostatic chuck.

[0051] This invention employs a pre-grinding paraffin sealing process to completely seal all helium pores before finishing, preventing grinding powder, abrasive, and debris from entering the pores and interior of porous ceramics from the source. This completely solves the industry problem of dense pores in porous ceramics being prone to slag buildup and traditional cleaning methods being unable to thoroughly clean them, effectively preventing pore blockage.

[0052] This invention features a simple process, controllable parameters, and high stability. It eliminates the traditional time-consuming and inefficient post-processing cleaning steps, significantly shortening processing time and reducing rework costs. It is suitable for the standardized and mass production needs of electrostatic chucks.

[0053] 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. A processing method for preventing contamination of the helium gas port of an electrostatic chuck, characterized in that, The processing method includes: Step S1: Heating and sealing the hole with melted wax The assembled electrostatic chuck is placed on a heating platform. After setting the heating temperature, it is heated until the overall temperature of the electrostatic chuck is uniform and stable. Then, paraffin wax is evenly applied to all the helium pores on the adsorption surface of the ceramic plate of the electrostatic chuck. The residual heat of the electrostatic chuck is used to completely melt the paraffin wax and allow it to naturally seep into the helium pores, filling them with liquid paraffin wax. The surface of the melted paraffin wax is flush with the surface of the ceramic plate of the electrostatic chuck. Each helium pore is checked to ensure that no pores are missed. Step S2: Cleaning residual wax from the plate After confirming that all helium gas holes are sealed, wipe the ceramic plate of the electrostatic chuck to remove excess paraffin wax around the helium gas holes and on the ceramic plate of the electrostatic chuck, leaving only the paraffin wax filling the helium gas holes to ensure that the working surface is flat and clean and to avoid surface residual wax interfering with subsequent grinding processes. Step S3: Natural cooling and shaping Remove the electrostatic chuck with the sealed hole from the heating platform and place it on a clean workbench to cool naturally to room temperature, allowing the paraffin inside the helium hole to completely solidify, forming a stable sealing structure and blocking the helium hole channel. Step S4: Surface grinding and polishing After cooling and shaping, the electrostatic chuck is clamped onto the grinding machine to grind and polish the adsorption working surface. Step S5: Primary overflow dewaxing and cleaning After grinding and polishing, the electrostatic chuck is placed in a hot water tank for cleaning. The tank is kept in a state of pure water overflow. Cleaning agent is added to the water. After the paraffin in the helium gas hole is completely melted by heat, it floats out of the tank with the overflowing pure water, keeping the water in the tank clean and removing the paraffin in the helium gas hole. Step S6: Secondary overflow cleaning After the electrostatic chuck has been dewaxed, it is transferred to a secondary hot water tank for further cleaning. The tank is kept overflowing with pure water to remove cleaning agent residue and trace impurities from the product surface and the inner walls of the micropores. Step S7: Rinse and dry, then proceed to the next step. After cleaning, the electrostatic chuck is rinsed thoroughly with high-purity hot water and then completely dried with clean nitrogen gas to complete the anti-contamination process for the helium gas holes of the electrostatic chuck.

2. The processing method for preventing contamination of the helium gas port of an electrostatic chuck according to claim 1, characterized in that, In step S1, the heating platform is heated to 80°C and the constant temperature heating time is at least 30 minutes to ensure that the electrostatic chuck temperature is uniform, the paraffin wax is fully melted, and the hole is fully filled.

3. The processing method for preventing contamination of the helium gas port of an electrostatic chuck according to claim 1, characterized in that, In step S4, water-based cutting fluid is used to grind and polish the adsorption working surface.

4. The processing method for preventing contamination of the helium gas port of an electrostatic chuck according to claim 1, characterized in that, In step S5, the water temperature in both the primary and secondary hot water tanks is 70°C, and the cleaning time for each tank is at least 30 minutes.