Preparation method of electrostatic chuck ceramic plate with optimized printing process

Abstract

The invention discloses a preparation method of an electrostatic chuck ceramic plate for optimizing a printing process, and belongs to the technical field of electrostatic chucks, and the preparation method comprises the following steps: S1, preparing adaptive printing slurry: preparing basic slurry; organic bentonite and triethanolamine are added into the basic slurry, ball milling continues, and improved printing slurry is obtained; s2, precise silk-screen printing is conducted, specifically, printing is conducted at the printing speed of 5 mm / s, and a printed green body is obtained; s3, three-stage gradient drying is conducted, specifically, the printing green body is put into a drying box, nitrogen with the purity being 99.99% is introduced, the pressure in the box is kept to be 0.01 MPa, constant-temperature drying is conducted for 30 min at the temperature of 25 DEG C, then the temperature is increased to 40 DEG C at the heating rate of 2-3 DEG C / min, constant-temperature drying is conducted for 30 min, and finally the temperature is increased to 60 DEG C at the heating rate of 2-3 DEG C / min, and constant-temperature drying is conducted for 30 min; s4, laminating: laminating the dried printing green body and other processed green bodies; and S5, atmosphere sintering: sintering the laminated body in a sintering furnace.

Description

Technical Field

[0001] This invention relates to the field of electrostatic chuck technology, and in particular to a method for preparing an electrostatic chuck ceramic disk with optimized printing process. Background Technology

[0002] Due to their excellent high-temperature resistance, insulation, and electrostatic adsorption stability, alumina electrostatic chucks have become core components in precision electronics manufacturing fields such as semiconductor wafer processing and LCD panel manufacturing. Screen printing is a crucial step in the preparation of alumina electrostatic chucks, used to print electrode patterns, insulating layers, and other functional structures on the surface of an alumina ceramic substrate. The drying quality of the printed green blank directly determines the subsequent sintering effect, thus affecting the uniformity of the electrostatic chuck's adsorption force, service life, and operational reliability.

[0003] In existing technologies, the drying of printed green bodies often employs either constant-temperature drying or irregular temperature-increasing drying methods, which have significant technical drawbacks: First, during constant-temperature drying, if the temperature is too high, the solvent in the printing paste on the surface of the green body evaporates rapidly, forming a dense outer shell that hinders the discharge of internal solvent. This results in residual solvent inside the green body after drying, which can easily cause bubbles and cracks during subsequent sintering due to rapid solvent evaporation. If the temperature is too low, the drying efficiency is low, and the solvent evaporation is insufficient, which also affects the sintering quality. Second, irregular temperature-increasing drying can easily lead to a large temperature gradient inside the green body, inducing internal stress and resulting in defects such as pattern deformation and edge cracking. Furthermore, existing drying processes are not synergistically matched with the characteristics of the printing paste and the pretreatment state of the substrate, further exacerbating the generation of drying defects and resulting in a low product yield of alumina electrostatic chucks. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing an electrostatic chuck ceramic disk with optimized printing process, so as to solve the problems mentioned in the background art.

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

[0006] A method for preparing an electrostatic chuck ceramic disk with optimized printing process, the method comprising:

[0007] S1. Adaptability of printing paste preparation:

[0008] Preparation of basic slurry: Weigh silver powder coated with 1wt% yttrium oxide, alumina micro powder, ethyl cellulose, dibutyl phthalate, and terpineol, add them to a planetary ball mill and ball mill to obtain the basic slurry;

[0009] Thixotropic control: Organic bentonite and triethanolamine were added to the base slurry prepared above, and ball milling was continued to adjust the slurry viscosity to 15000-20000 mPa·s to obtain the modified printing slurry;

[0010] S2. Precision screen printing:

[0011] The screen printing environment temperature is 20℃ and the relative humidity is 40%. The printing is carried out with a squeegee angle of 45°, a pressure of 0.2MPa and a printing speed of 5mm / s. After printing, the surface is purged with nitrogen to obtain the printed blank.

[0012] S3. Three-stage gradient drying:

[0013] Place the printed blank into a drying oven, introduce nitrogen gas with a purity of 99.99%, maintain the pressure inside the oven at 0.01 MPa, first dry at a constant temperature of 25℃ for 30 min, then raise the temperature to 40℃ at a heating rate of 2-3℃ / min, dry at a constant temperature for 30 min, and finally raise the temperature to 60℃ at a heating rate of 2-3℃ / min, dry at a constant temperature for 30 min.

[0014] S4. Overlay:

[0015] The dried printing preforms are stacked together with other processed preforms by positioning and stacking to form a complete laminate. The pressure, time and temperature are controlled during the stacking process to prevent the preforms from not being completely and tightly bonded together.

[0016] S5. Atmosphere sintering:

[0017] The laminated body is placed in a sintering furnace, nitrogen is introduced to replace the air in the sintering furnace, the temperature is raised to 600℃ and held, then the temperature is raised to 1200℃, the argon-hydrogen mixed atmosphere is switched and held, after sintering, the temperature is lowered to 600℃, the nitrogen atmosphere is switched, and it is naturally cooled to room temperature to obtain an alumina electrostatic chuck ceramic disc.

[0018] Preferably, in step S1,

[0019] Preparation of basic slurry: By weight, take 50 parts of silver powder coated with 1wt% yttrium oxide, 10 parts of alumina micro powder, 5 parts of ethyl cellulose, 2 parts of dibutyl phthalate, and 15 parts of terpineol, add them to a planetary ball mill, and ball mill at 200 r / min for 4 h to obtain the basic slurry. The particle size of the silver powder is 0.5-1 μm, and the particle size of the alumina micro powder is 0.1-0.2 μm.

[0020] Thixotropic control: Add 0.5 parts of organobentonite and 0.3 parts of triethanolamine to the base slurry prepared above, continue ball milling for 30 min, and adjust the slurry viscosity to 15000~20000mPa·s at 25℃ to obtain the improved printing slurry.

[0021] Preferably, in step S2, a 300-mesh stainless steel screen is selected for screen printing, with a screen tension of 25 N / cm, a screen film thickness of 15 μm, a positioning accuracy error of less than or equal to ±0.02 mm, and a polyurethane squeegee with a Shore hardness of 70A is selected.

[0022] Preferably, in step S3, the nitrogen flow rate is 0.2 L / min, and the temperature is first kept constant at 25°C for 30 min, then increased to 40°C at 2°C / min and kept constant at 40°C for 30 min, and then increased to 60°C at 2°C / min and kept constant at 60°C for 30 min.

[0023] Preferably, in step S4, the pressure during stacking is 20T to 200T, the temperature is 30 to 80℃, and the time is 1 to 10 minutes.

[0024] Preferably, in step S5, nitrogen gas is introduced into the sintering furnace for 30 minutes to purge the furnace, the temperature is increased to 600°C at 5°C / min and held for 90 minutes, then the temperature is increased to 1200°C at 3°C / min, and the atmosphere of argon-hydrogen mixture is switched to be introduced and held for 180 minutes. The volume ratio of argon to hydrogen in the argon-hydrogen mixture is 9:1 and the flow rate is 0.5 L / min. After sintering, the temperature is reduced to 600°C at 4°C / min, the atmosphere of nitrogen is switched, and the furnace is allowed to cool naturally to room temperature to obtain an alumina electrostatic chuck ceramic disk.

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

[0026] 1. A three-stage gradient drying process of "25℃-40℃-60℃" is adopted, and the drying time of each stage is precisely controlled at 30 minutes. With a gentle heating rate of 2-3℃ / min, an orderly transition of "preliminary surface evaporation-internal diffusion evaporation-complete evaporation" of the solvent in the printing blank is achieved. The low temperature stage of 25℃ avoids the rapid evaporation of surface solvent to form an outer shell, the transition stage of 40℃ promotes uniform diffusion of internal solvent, and the final stage of 60℃ ensures complete removal of solvent. This fundamentally solves the problems of uneven solvent evaporation and high internal stress in traditional drying processes, and significantly reduces drying defects such as bubbles, cracks, and deformation.

[0027] 2. The gradient drying process of this application, together with the improved printing paste and the precise pretreatment process, form a synergistic fit: the thixotropic and viscosity characteristics of the improved paste ensure that the paste does not easily flow during the gradient drying process, and the surface condition of the substrate after pretreatment improves the bonding stability between the paste and the substrate. The three work together to further improve the integrity and edge clarity of the printed pattern.

[0028] 3. The micro-positive pressure environment and nitrogen protection design during the drying process effectively prevent external dust from contaminating the green body, while reducing the oxidation of slurry components, laying a good foundation for the subsequent sintering process; the optimization of parameters in the subsequent atmosphere sintering process further strengthens the bonding strength between the printed layer and the alumina substrate, and improves the functional stability and service life of the electrostatic chuck.

[0029] 4. The process steps of this application are clear and the parameters are highly controllable. The temperature and time parameters of gradient drying are easy to promote industrially. No complex equipment modification is required. It can effectively improve the product qualification rate of alumina electrostatic chucks, reduce production costs, and has broad application prospects. Detailed Implementation

[0030] 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.

[0031] The purpose of this invention is to overcome the problems of uneven solvent evaporation, high internal stress, and easy defects in the existing alumina electrostatic chuck printing green blank drying process, and to provide a method for preparing an electrostatic chuck ceramic disc with an optimized printing process.

[0032] The core of this method is to dry the printed preform through a customized three-stage gradient drying process, combined with the synergistic optimization of substrate pretreatment, slurry preparation and printing operation, so as to achieve slow and uniform evaporation of solvent in the printed preform, reduce internal stress and drying defects, improve the adhesion between the printed layer and the substrate, and thus improve the product quality and pass rate of alumina electrostatic chucks.

[0033] A method for preparing an electrostatic chuck ceramic disk with optimized printing process, the method specifically includes the following steps:

[0034] S1. Adaptability of printing paste preparation:

[0035] Preparation of basic slurry: Weigh silver powder coated with 1wt% yttrium oxide, alumina micro powder, ethyl cellulose, dibutyl phthalate, and terpineol, add them to a planetary ball mill and ball mill to obtain the basic slurry;

[0036] Thixotropic control: Organic bentonite and triethanolamine were added to the base slurry prepared above, and ball milling was continued to adjust the slurry viscosity to 15000-20000 mPa·s to obtain the modified printing slurry;

[0037] Specifically, the prepared printing paste is an electrode paste. The preparation of the aforementioned basic paste involves: taking 50 parts by weight of silver powder coated with 1 wt% yttrium oxide, 10 parts of alumina micropowder, 5 parts of ethyl cellulose, 2 parts of dibutyl phthalate, and 15 parts of terpineol, adding them to a planetary ball mill, milling at 200 r / min for 4 hours to obtain the basic paste. The silver powder has a particle size of 0.5–1 μm, and the alumina micropowder has a particle size of 0.1–0.2 μm. Specifically, the silver powder has an average particle size of 0.5 μm or 1 μm, and the alumina micropowder also has an average particle size of 0.1 μm or 0.2 μm.

[0038] Thixotropic adjustment: Add 0.5 parts of organobentonite and 0.3 parts of triethanolamine to the base slurry prepared above, and continue ball milling for 30 min to adjust the slurry viscosity to 15000-20000 mPa·s at 25℃ to obtain the modified printing slurry. Specifically, the viscosity of the slurry is 15000 mPa·s (25℃) or 20000 mPa·s (25℃), or it can be 1800 mPa·s (25℃).

[0039] S2. Precision screen printing:

[0040] The screen printing environment temperature is 20℃ and the relative humidity is 40%. The printing is carried out with a squeegee angle of 45°, a pressure of 0.2MPa and a printing speed of 5mm / s. After printing, the surface is purged with nitrogen to obtain the printed blank.

[0041] In addition, the screen printing uses a 300-mesh stainless steel screen with a screen tension of 25 N / cm, a screen film thickness of 15 μm, a positioning accuracy error of less than or equal to ±0.02 mm, and a polyurethane squeegee with a Shore hardness of 70A.

[0042] S3. Three-stage gradient drying:

[0043] The printed blank is placed in a drying oven and purged with 99.99% pure nitrogen gas. The pressure inside the drying oven is maintained at 0.01 MPa. First, it is dried at a constant temperature of 25℃ for 30 minutes. Then, the temperature is increased to 40℃ at a rate of 2-3℃ / min and dried at a constant temperature for 30 minutes. Finally, the temperature is increased to 60℃ at a rate of 2-3℃ / min and dried at a constant temperature for 30 minutes. Specifically, the heating rate to 40℃ is 2℃ / min or 3℃ / min, and the heating rate to 60℃ is 2℃ / min or 3℃ / min.

[0044] Specifically, the nitrogen flow rate is 0.2 L / min. First, dry at a constant temperature of 25℃ for 30 min, then increase the temperature to 40℃ at 2℃ / min and dry at a constant temperature for 30 min, then increase the temperature to 60℃ at 2℃ / min and dry at a constant temperature for 30 min.

[0045] The process employs a three-stage gradient drying process of 25℃-40℃-60℃, with each stage precisely controlled to a drying time of 30 minutes. Combined with a gentle heating rate of 2-3℃ / min, this achieves an orderly transition of the solvent in the printing preform from initial surface evaporation to internal diffusion evaporation to complete evaporation. The 25℃ low-temperature stage prevents the rapid evaporation of surface solvents to form an outer shell, the 40℃ transition stage promotes uniform diffusion of internal solvents, and the 60℃ final stage ensures complete solvent removal. This fundamentally solves the problems of uneven solvent evaporation and high internal stress in traditional drying processes, and significantly reduces drying defects such as bubbles, cracks, and deformation.

[0046] The micro-positive pressure environment and nitrogen protection design during the drying process effectively prevent external dust from contaminating the green body, while reducing the oxidation of slurry components, laying a good foundation for the subsequent sintering process; the optimization of parameters in the subsequent atmosphere sintering process further strengthens the bonding strength between the printed layer and the alumina substrate, and improves the functional stability and service life of the electrostatic chuck.

[0047] S4. Overlay:

[0048] The dried printing preforms are stacked together with other processed preforms using a positioning and stacking method to form a complete laminate. The pressure, time, and temperature are controlled during the stacking process to prevent the preforms from not being completely and tightly bonded. The pressure during stacking is 20T to 200T, the temperature is 30 to 80℃, and the time is 1 to 10 minutes. Specifically, the pressure during stacking is 20T or 200T, the temperature is 30℃ or 80℃, and the time is 1 minute or 10 minutes.

[0049] S5. Atmosphere sintering:

[0050] The laminated body is placed in a sintering furnace, nitrogen is introduced to replace the air in the sintering furnace, the temperature is raised to 600℃ and held, then the temperature is raised to 1200℃, the argon-hydrogen mixed atmosphere is switched and held, after sintering, the temperature is lowered to 600℃, the nitrogen atmosphere is switched, and it is naturally cooled to room temperature to obtain an alumina electrostatic chuck ceramic disc.

[0051] Specifically, nitrogen gas is introduced into the sintering furnace for 30 minutes to purge the gas, the temperature is increased to 600°C at a rate of 5°C / min and held for 90 minutes, then the temperature is increased to 1200°C at a rate of 3°C / min. The atmosphere is then switched to an argon-hydrogen mixture and held for 180 minutes. The volume ratio of argon to hydrogen in the argon-hydrogen mixture is 9:1 and the flow rate is 0.5 L / min. After sintering, the temperature is decreased to 600°C at a rate of 4°C / min, the atmosphere is switched to nitrogen, and the mixture is allowed to cool naturally to room temperature to obtain an alumina electrostatic chuck ceramic disc.

[0052] The gradient drying process of this application, together with the improved printing paste and the precise pretreatment process, forms a synergistic fit: the thixotropic and viscosity characteristics of the improved paste ensure that the paste is not prone to flow during the gradient drying process, and the surface condition of the substrate after pretreatment improves the bonding stability between the paste and the substrate. The three work together to further improve the integrity and edge clarity of the printed pattern.

[0053] This application features clear process steps, highly controllable parameters, and easily industrially applicable temperature and time parameters for gradient drying. It requires no complex equipment modifications, effectively improving the product qualification rate of alumina electrostatic chucks and reducing production costs, thus demonstrating broad application prospects.

[0054] This application uses a casting process to form ceramic green sheets. The ceramic green sheets are stacked to the required thickness using a positioning and pressing method. A basic printing paste is prepared, and precise screen printing is performed. The printed green sheets are then placed in a drying oven and dried using a three-stage temperature gradient program. The tightly bonded ceramic blocks are placed in a debinding furnace for degreasing and debinding. After debinding, they are sintered at high temperature in a sintering furnace to form ceramic. The resulting electrostatic chuck ceramic disc is then complete.

[0055] 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 method for preparing an electrostatic chuck ceramic disk with optimized printing process, characterized in that, The method includes: S1. Adaptability of printing paste preparation: Preparation of basic slurry: Weigh silver powder coated with 1wt% yttrium oxide, alumina micro powder, ethyl cellulose, dibutyl phthalate, and terpineol, add them to a planetary ball mill and ball mill to obtain the basic slurry; Thixotropic control: Organic bentonite and triethanolamine were added to the base slurry prepared above, and ball milling was continued to adjust the slurry viscosity to 15000-20000 mPa·s to obtain the modified printing slurry; S2. Precision screen printing: The screen printing environment temperature is 20℃ and the relative humidity is 40%. The printing is carried out with a squeegee angle of 45°, a pressure of 0.2MPa and a printing speed of 5mm / s. After printing, the surface is purged with nitrogen to obtain the printed blank. S3. Three-stage gradient drying: Place the printed blank into a drying oven, introduce nitrogen gas with a purity of 99.99%, maintain the pressure inside the oven at 0.01 MPa, first dry at a constant temperature of 25℃ for 30 min, then raise the temperature to 40℃ at a heating rate of 2-3℃ / min, dry at a constant temperature for 30 min, and finally raise the temperature to 60℃ at a heating rate of 2-3℃ / min, dry at a constant temperature for 30 min. S4. Overlay: The dried printing preforms are stacked together with other processed preforms by positioning and stacking to form a complete laminate. The pressure, time and temperature are controlled during the stacking process to prevent the preforms from not being completely and tightly bonded together. S5. Atmosphere sintering: The laminated body is placed in a sintering furnace, nitrogen is introduced to replace the air in the sintering furnace, the temperature is raised to 600℃ and held, then the temperature is raised to 1200℃, the argon-hydrogen mixed atmosphere is switched and held, after sintering, the temperature is lowered to 600℃, the nitrogen atmosphere is switched, and it is naturally cooled to room temperature to obtain an alumina electrostatic chuck ceramic disc.

2. The method for preparing an electrostatic chuck ceramic disk with optimized printing process according to claim 1, characterized in that, In step S1 Preparation of basic slurry: By weight, take 50 parts of silver powder coated with 1wt% yttrium oxide, 10 parts of alumina micro powder, 5 parts of ethyl cellulose, 2 parts of dibutyl phthalate, and 15 parts of terpineol, add them to a planetary ball mill, and ball mill at 200 r / min for 4 h to obtain the basic slurry. The particle size of the silver powder is 0.5-1 μm, and the particle size of the alumina micro powder is 0.1-0.2 μm. Thixotropic control: Add 0.5 parts of organobentonite and 0.3 parts of triethanolamine to the base slurry prepared above, continue ball milling for 30 min, and adjust the slurry viscosity to 15000~20000mPa·s at 25℃ to obtain the improved printing slurry.

3. The method for preparing an electrostatic chuck ceramic disk with optimized printing process according to claim 1, characterized in that, In step S2, a 300-mesh stainless steel screen is selected for screen printing, with a screen tension of 25 N / cm, a screen film thickness of 15 μm, a positioning accuracy error of less than or equal to ±0.02 mm, and a polyurethane squeegee with a Shore hardness of 70A is selected.

4. The method for preparing an electrostatic chuck ceramic disk with optimized printing process according to claim 1, characterized in that, In step S3, the nitrogen flow rate is 0.2 L / min. First, the temperature is kept constant at 25°C for 30 min. Then, the temperature is increased to 40°C at 2°C / min and kept constant at 40°C for 30 min. Finally, the temperature is increased to 60°C at 2°C / min and kept constant at 60°C for 30 min.

5. The method for preparing an electrostatic chuck ceramic disk with optimized printing process according to claim 1, characterized in that, In step S4, the pressure during stacking is 20T to 200T, the temperature is 30 to 80℃, and the time is 1 to 10 minutes.

6. The method for preparing an electrostatic chuck ceramic disk with optimized printing process according to claim 1, characterized in that, In step S5, nitrogen gas is introduced into the sintering furnace for 30 minutes to purge the gas, the temperature is increased to 600°C at 5°C / min and held for 90 minutes, then the temperature is increased to 1200°C at 3°C / min, and the atmosphere of argon-hydrogen mixture is switched to be introduced and held for 180 minutes. The volume ratio of argon to hydrogen in the argon-hydrogen mixture is 9:1 and the flow rate is 0.5 L / min. After sintering, the temperature is reduced to 600°C at 4°C / min, the atmosphere of nitrogen is switched, and the mixture is allowed to cool naturally to room temperature to obtain an alumina electrostatic chuck ceramic disk.