Electrostatic-vacuum composite chuck and preparation method thereof

Abstract

The invention discloses an electrostatic-vacuum composite chuck and a preparation method thereof. The electrostatic-vacuum composite chuck comprises a base and a ceramic layer, the ceramic layer is welded and fixed on the base, and the ceramic layer is composed of aluminum nitride compact ceramic and aluminum nitride porous ceramic. The functions of a vacuum chuck and an electrostatic chuck are achieved, the functions of the vacuum chuck are achieved, aluminum nitride compact ceramic is provided with air holes leading to an air groove, the air groove is provided with an exhaust hole used for being connected with a vacuum pump to generate negative pressure, and due to the fact that aluminum nitride porous ceramic and an adsorbed workpiece have the negative pressure, workpiece adsorption is achieved; according to the electrostatic chuck, an electrode in the aluminum nitride compact ceramic is connected to a direct-current high-voltage power source, polarization is generated in the ceramic, an adsorbed workpiece is polarized, and electrostatic force is generated to achieve workpiece adsorption; an aluminum nitride material is adopted, the heat conductivity of the aluminum nitride material is higher than that of an aluminum oxide material, and compared with the aluminum oxide material and a silicon carbide material, the aluminum nitride material is more beneficial to heat management and uniform in temperature.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device manufacturing technology, and in particular to an electrostatic-vacuum composite chuck and its preparation method. Background Technology

[0002] Electrostatic chucks and vacuum chucks are commonly used in the semiconductor manufacturing industry and are the mainstream adsorption technologies.

[0003] An electrostatic chuck (ESC) is a device that uses electrostatic adsorption to fix and support silicon wafers or other working media. It is widely used in semiconductor manufacturing, microelectronics processing, vacuum deposition, and other fields, especially in processes such as ion implantation, etching, physical vapor deposition (PVD), and chemical vapor deposition (CVD). The working principle of an ESC is that by applying a DC or AC voltage to electrodes embedded within it, an electrostatic field is formed between the chuck surface and the working media. This electrostatic field generates a strong adsorption force, firmly adsorbing the silicon wafer or other working media onto the chuck surface. This adsorption force is not only strong enough to maintain the positional stability of the working media during processing, but it also reduces the thermal resistance between the working media and the chuck, facilitating heat conduction and dissipation. However, ESCs are generally suitable for vacuum and plasma environments and cannot be used for vacuum adsorption.

[0004] A vacuum suction cup is a device that uses the principle of vacuum negative pressure to adsorb and fix objects. It creates a partial vacuum, forming a negative pressure difference between the suction cup and the object being adsorbed, thus achieving a firm adsorption effect. Vacuum suction cups are widely used in various automated equipment and production lines, especially in material handling, packaging, and assembly. However, vacuum suction cups cannot perform electrostatic adsorption and cannot operate in a vacuum environment.

[0005] This invention presents an electrostatic-vacuum composite chuck that combines the functions of an electrostatic chuck and a vacuum chuck. In special environments such as vacuum and plasma, the electrostatic chuck functions normally, while the vacuum chuck provides support in non-vacuum environments. Furthermore, this electrostatic-vacuum composite chuck offers dual adsorption forces, significantly improving adsorption stability. The vacuum chuck is suitable for various materials, such as metals, plastics, and glass, while the electrostatic chuck is suitable for conductive or dielectric materials, such as silicon wafers and crystal wafers. This electrostatic-vacuum composite chuck enables the adsorption of a wider variety of items. Summary of the Invention

[0006] In view of this, the present invention addresses the deficiencies of the existing technology, and its main objective is to provide an electrostatic-vacuum composite chuck and its preparation method, which is compatible with the functions of an electrostatic chuck and a vacuum chuck, can achieve multiple uses in one piece, can adapt to different process conditions, and can adsorb items of various materials.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: An electrostatic-vacuum composite chuck includes a base and a ceramic layer; the ceramic layer is welded and fixed to the base, and the ceramic layer is composed of dense aluminum nitride ceramic and porous aluminum nitride ceramic.

[0008] As a preferred embodiment, the aluminum nitride dense ceramic comprises the following raw materials by weight percentage: AlN 85-90%, CeO2 2-5%, YF3 2-5%, CaF2 2-5%, and Y2O3 2-5%.

[0009] As a preferred embodiment, the porous aluminum nitride ceramic comprises the following raw materials by weight percentage: AlN 85-90%, MgF2 2-5%, YF3 2-5%, CaF2 2-5%, and Y2O3 2-5%.

[0010] As a preferred embodiment, the aluminum nitride dense ceramic and the aluminum nitride porous ceramic are welded together using a glaze, which comprises the following raw materials by weight percentage: SiO2 75-90%, Al2O3 10-15%, BaO 5-10%, and K2O 5-10%.

[0011] As a preferred embodiment, the base is provided with positive and negative adsorption electrode holes, air extraction holes, coolant inlet and outlet, and multiple LIFT PIN holes, and the base is provided with coolant flow channels.

[0012] As a preferred embodiment, the aluminum nitride dense ceramic is provided with pores and multiple uniformly distributed LIFTPIN pores, the aluminum nitride dense ceramic is provided with an adsorption circuit, the front side of the aluminum nitride dense ceramic is provided with a groove, the aluminum nitride dense ceramic is provided with a number of exhaust holes penetrating the ceramic, and the adsorption circuit is provided with a set of positive and negative electrodes.

[0013] As a preferred embodiment, the porous aluminum nitride ceramic is provided with pores, which are used to create a vacuum and form a negative pressure. The workpiece is fixed on the chuck surface by the pressure difference between the negative pressure generated in the porous aluminum nitride ceramic and the atmospheric pressure.

[0014] As a preferred embodiment, the method for preparing the aluminum nitride dense ceramic includes the following steps: (1) Slurry preparation method: The raw materials for preparing aluminum nitride dense ceramics are mixed in a certain proportion. The components are AlN, CeO2, YF3, CaF2 and Y2O3, with a particle size of 0.2-3μm. The raw materials are weighed accurately in a certain proportion. Based on the powder mass, 45-55 parts by weight of solvent and 0.5-2.5 parts by weight of dispersant are added and put into a ball mill containing 200-300 parts by weight of alumina balls with a particle size of 5-15mm. The mixture is processed at a speed of 40-70r / min for 12-24 hours. Then, 7-11 parts by weight of binder and 4-8 parts by weight of plasticizer are added to the ball mill. The ball milling is continued for 12-24 hours. The ball-milled slurry is degassed for 1-2 hours to obtain a casting slurry with a viscosity of 5000-10000mPa.s. (2) Casting and cutting: The degassed casting slurry is formed using a casting machine to obtain a ceramic green porcelain strip with a diameter of 0.3-0.6mm, which is then cut into ceramic green porcelain pieces of uniform size by a cutting machine; (3) Printing and filling holes: After drilling holes in the ceramic raw ceramic pieces, a printing press is used to print and fill the holes with metal paste; (4) Stacking: After printing, the ceramic green porcelain sheets are stacked and placed on a pad, put into a vacuum bag and vacuum sealed. After sealing, they are placed in an isostatic press and pressed for 10-30 minutes at 60-80℃ and 10-40MPa to obtain ceramic green porcelain plates. (5) Debinding: Place the ceramic raw porcelain plate on the corundum mullite firing plate, put it into the debinding furnace, and slowly heat it to 450-650℃ at a heating rate of 0.3-1℃ / min. Hold it for 3-6 hours to obtain the ceramic debinding sheet. (6) Sintering: The ceramic sheet is placed into a high-temperature sintering furnace and sintered at 1750-1850℃ for 2-4 hours to obtain the ceramic sintered sheet; (7) Machining: The sintered ceramic sheets are machined according to the drawings using machining equipment to obtain aluminum nitride dense ceramics with a flatness of <5μm and a surface roughness of <0.1μm.

[0015] As a preferred embodiment, the method for preparing the porous aluminum nitride ceramic includes the following steps: (1) Preparation of slurry: The raw materials for preparing porous aluminum nitride ceramics are mixed in a certain proportion. The components are AlN, MgF2, YF3, CaF2 and Y2O3, with a particle size of 0.2-3μm. The raw materials are weighed accurately in a certain proportion. Based on the powder mass, 10-30 parts by weight of pore-forming agent, 15-30 parts by weight of calcium fluoride, 0.1-1 parts by weight of yttrium fluoride, 45-55 parts by weight of solvent, and 0.5-2.5 parts by weight of dispersant are added. The agent is fed into a ball mill containing 200-300 parts by weight of alumina balls with a particle size of 5-15 mm, and processed at a speed of 40-70 r / min for 12-24 hours; then 7-11 parts by weight of binder and 4-8 parts by weight of plasticizer are added to the ball mill, and ball milling is continued for 12-24 hours to obtain a uniformly mixed granulated slurry; the pore-forming agent is one or more of polymethyl methacrylate, carboxymethyl cellulose and polyurethane, and the pore-forming agent has a particle size of 30-60 μm; (2) Granulation: The mixed granulation slurry is granulated using a granulator to obtain granulated powder with a particle size of 50-100μm, and then sieved and batched using a vibrating screen; (3) Dry pressing: The granulated powder is poured into the mold using a hydraulic press and aluminum nitride dry blank is obtained under a pressure of 500T; (4) Isostatic pressing: The obtained aluminum nitride blank is vacuum sealed using a vacuum packaging machine. After sealing, it is placed in an isostatic press and pressed for 10-30 minutes at 60-80℃ and 150-200MPa to obtain a ceramic green porcelain plate. (5) Sintering: The ceramic raw porcelain plate is placed in a high-temperature sintering furnace and sintered at 1600-1850℃ for 2-4 hours to obtain sintered ceramic structural parts; (6) Machining: The sintered ceramic structural parts are finally processed by double-sided grinding and machining equipment to obtain aluminum nitride porous ceramics with a flatness of <5μm and a surface roughness of less than 0.1μm.

[0016] A method for preparing an electrostatic-vacuum composite chuck, comprising the following steps: A combination of porous aluminum nitride ceramic and dense aluminum nitride ceramic. (1) Machining of aluminum nitride dense ceramics: Based on the product structure design, use ultrasonic CNC equipment to process aluminum nitride dense ceramics to prepare groove structures that meet the design specifications and facilitate assembly, as well as air extraction holes and airflow channels for vacuuming. (2) Machining of porous aluminum nitride ceramics: Based on the product structure design, porous aluminum nitride ceramics are machined using ultrasonic CNC equipment to prepare porous aluminum nitride ceramic structural parts that can be embedded in the grooves of dense aluminum nitride ceramics. (3) Glaze preparation: The raw materials for preparing the glaze for aluminum nitride ceramics are mixed in a certain proportion. The components are SiO2, Al2O3, BaO, and K2O, with a particle size of 1-4μm. The raw materials are weighed accurately in a certain proportion. Based on the powder mass, 15-30 parts by weight of calcium fluoride, 0.1-1 parts by weight of yttrium fluoride, 35-50 parts by weight of solvent, 0.5-3 parts by weight of binder, and 0.3-1.5 parts by weight of dispersant are put into a ball mill containing 200-300 parts by weight of alumina balls with a particle size of 5-15mm. The mixture is processed at a speed of 120-150r / min for 12-24 hours to obtain a uniformly mixed granulated slurry. The solvent is one or more of ethanol, terpineol, ethyl acetate, and isopropanol. The binder is polyvinyl butyral. (4) Assembly welding: The prepared glaze is evenly coated on the upper surface of the groove wall of the aluminum nitride dense ceramic. The aluminum nitride porous ceramic is placed in the groove of the aluminum nitride dense ceramic according to the structural design to form an assembly. The assembly is placed in a drying oven and baked at 70-90℃ for 2-4 hours. After the glaze is dried, it is transferred to a high-temperature vacuum welding furnace and kept at 1000-1200℃ for 20-50 minutes. The combination of aluminum nitride porous ceramic and aluminum nitride dense ceramic to form a ceramic layer is completed after welding.

[0017] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, as can be seen from the above technical solution: An electrostatic-vacuum composite chuck combines the working principles of an electrostatic chuck and a vacuum chuck. The electrostatic chuck works by generating an electrostatic field in the dense aluminum nitride ceramic after energization, attracting objects. The vacuum chuck works by connecting a vacuum pump to generate negative pressure, attracting objects. This electrostatic-vacuum composite chuck can simultaneously achieve the working principles of both electrostatic chucks and vacuum chucks, meaning it can initiate electrostatic and vacuum adsorption simultaneously, making it suitable for applications requiring extremely high stability and precision.

[0018] Compared to existing electrostatic chucks or vacuum chucks, the electrostatic-vacuum composite chuck of this invention combines the functions of both, replacing single-function vacuum chucks or electrostatic chucks and applicable to a wider range of process conditions. The vacuum chuck provides strong mechanical adsorption, while the electrostatic chuck provides uniform electrostatic adsorption; the combined dual adsorption force significantly improves adsorption stability. This allows a single device to meet multiple processing requirements, increasing equipment utilization.

[0019] To more clearly illustrate the structural features and effects of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0020] Figure 1This is an exploded view of an electrostatic-vacuum composite chuck of the present invention; Figure 2 This is a scanning electron microscope image of the porous aluminum nitride ceramic in Embodiment 1 of the present invention; Figure 3 This is a scanning electron microscope image of the porous aluminum nitride ceramic in Embodiment 2 of the present invention.

[0021] Explanation of reference numerals in the attached diagram: 10. Base; 11. Positive and negative adsorption electrode holes; 12. Air extraction hole; 13. First LIFT PIN hole; 20. Ceramic layer; 21. Dense aluminum nitride ceramic; 22. Porous aluminum nitride ceramic; 23. Adsorption circuit; 201. Second LIFT PIN hole; 202. Trench. Detailed Implementation

[0022] The present invention discloses an electrostatic-vacuum composite chuck, comprising a base 10 and a ceramic layer 20; the ceramic layer 20 is welded and fixed on the base 10, and the ceramic layer 20 is composed of aluminum nitride dense ceramic 21 and aluminum nitride porous ceramic 22.

[0023] The base 10 is provided with positive and negative adsorption electrode holes 11, air extraction holes 12, coolant inlet and outlet (not shown in the figure) and multiple first LIFT PIN holes 13, and the base 10 is provided with coolant flow channels (not shown in the figure).

[0024] The aluminum nitride dense ceramic 21 comprises the following raw materials by weight percentage: AlN 85-90%, CeO2 2-5%, YF3 2-5%, CaF2 2-5%, and Y2O3 2-5%. The aluminum nitride dense ceramic 21 has a first pore and multiple uniformly distributed second LIFT PIN holes 201. An adsorption circuit 23 is provided within the aluminum nitride dense ceramic 21. A groove 202 is provided on the front side of the aluminum nitride dense ceramic 21. Several through-holes are provided in the aluminum nitride dense ceramic 21 for venting. A set of positive and negative electrodes is provided in the adsorption circuit 23. The preparation method of the aluminum nitride dense ceramic 21 includes the following steps: (1) Slurry preparation method: The raw materials for preparing aluminum nitride dense ceramic 21 are mixed in a certain proportion. The components are AlN, CeO2, YF3, CaF2 and Y2O3, with a particle size of 0.2-3μm. The raw materials are weighed accurately in a certain proportion. Based on the powder mass, 45-55 parts by weight of solvent and 0.5-2.5 parts by weight of dispersant are added and put into a ball mill containing 200-300 parts by weight of alumina balls with a particle size of 5-15mm. The mixture is processed at a speed of 40-70r / min for 12-24 hours. Then, 7-11 parts by weight of binder and 4-8 parts by weight of plasticizer are added to the ball mill. The ball milling continues for 12-24 hours. The ball-milled slurry is degassed for 1-2 hours to obtain a casting slurry with a viscosity of 5000-10000mPa.s.

[0025] (2) Casting and cutting: The degassed casting slurry is formed by casting machine to obtain a ceramic green porcelain strip with a diameter of 0.3-0.6mm, which is then cut into ceramic green porcelain pieces of uniform size by cutting machine.

[0026] (3) Printing and filling holes: After drilling holes in the ceramic raw ceramic pieces, a printing press is used to print and fill the holes with metal paste. (4) Stacking: After printing, the ceramic raw porcelain sheets are stacked and placed on a pad, put into a vacuum bag and vacuum sealed. After sealing, they are placed in an isostatic press and pressed for 10-30 minutes at 60-80℃ and 10-40MPa to obtain ceramic raw porcelain plates.

[0027] (5) Debinding: Place the ceramic raw porcelain plate on the corundum mullite firing plate and put it into the debinding furnace. Slowly heat the temperature to 450-650℃ at a heating rate of 0.3-1℃ / min and keep it at the temperature for 3-6 hours to obtain the ceramic debinding sheet.

[0028] (6) Sintering: The ceramic sheet is placed into a high-temperature sintering furnace and sintered at 1750-1850℃ for 2-4 hours to obtain the ceramic sintered sheet.

[0029] (7) Machining: The sintered ceramic sintered sheets are machined according to the drawings using machining equipment to obtain aluminum nitride dense ceramic 21 with a flatness of <5μm and a surface roughness of <0.1μm.

[0030] The aluminum nitride porous ceramic 22 comprises the following raw materials by weight percentage: AlN 85-90%, MgF2 2-5%, YF3 2-5%, CaF2 2-5%, and Y2O3 2-5%. The aluminum nitride porous ceramic 22 has a second pore, which is used to create a negative pressure through vacuuming. The pressure difference between the negative pressure generated within the aluminum nitride porous ceramic 22 and atmospheric pressure fixes the workpiece on the chuck surface. The preparation method of the aluminum nitride porous ceramic 22 includes the following steps: (1) Preparation of slurry: The raw materials for preparing porous aluminum nitride ceramic 22 are mixed in a certain proportion. The components are AlN, MgF2, YF3, CaF2 and Y2O3, with a particle size of 0.2-3μm. The raw materials are weighed accurately in a certain proportion. Based on the powder mass, 10-30 parts by weight of pore-forming agent, 15-30 parts by weight of calcium fluoride, 0.1-1 parts by weight of yttrium fluoride, 45-55 parts by weight of solvent, and 0.5-2.5 parts by weight of component are added. The powder is fed into a ball mill containing 200-300 parts by weight of alumina balls with a particle size of 5-15 mm, and processed at a speed of 40-70 r / min for 12-24 hours; then 7-11 parts by weight of binder and 4-8 parts by weight of plasticizer are added to the ball mill, and ball milling is continued for 12-24 hours to obtain a uniformly mixed granulated slurry; the pore-forming agent is one or more of polymethyl methacrylate, carboxymethyl cellulose and polyurethane, and the pore-forming agent has a particle size of 30-60 μm.

[0031] (2) Granulation: The mixed granulation slurry is granulated using a granulator to obtain granulated powder with a particle size of 50-100μm, and then sieved and batched using a vibrating screen.

[0032] (3) Dry pressing: The granulated powder is poured into the mold using a hydraulic press and aluminum nitride dry blank is obtained under a pressure of 500T.

[0033] (4) Isostatic pressing: The obtained aluminum nitride blank is vacuum sealed using a vacuum packaging machine. After sealing, it is placed in an isostatic press and pressed for 10-30 minutes at 60-80℃ and 150-200MPa to obtain a ceramic green porcelain plate.

[0034] (5) Sintering: The ceramic raw porcelain plate is placed into a high-temperature sintering furnace and sintered at 1600-1850℃ for 2-4 hours to obtain sintered ceramic structural parts.

[0035] (6) Machining: The sintered ceramic structural parts are finally processed by double-sided grinding and machining equipment to obtain aluminum nitride porous ceramic 22 with a flatness of <5μm and a surface roughness of less than 0.1μm.

[0036] The aluminum nitride dense ceramic 21 and aluminum nitride porous ceramic 22 are welded together using a glaze, which includes the following raw materials by weight percentage: SiO2 75-90%, Al2O3 10-15%, BaO 5-10%, and K2O 5-10%.

[0037] This invention also discloses a method for preparing the aforementioned electrostatic-vacuum composite chuck, wherein the method for combining porous aluminum nitride ceramic 22 and dense aluminum nitride ceramic 21 includes the following steps: (1) Machining of aluminum nitride dense ceramic 21: According to the product structure design, the aluminum nitride dense ceramic 21 is machined using ultrasonic CNC equipment to prepare a groove 202 structure that conforms to the design specifications and is easy to assemble, as well as a vacuum hole and airflow channel for vacuuming.

[0038] (2) Machining of aluminum nitride porous ceramic 22: According to the product structure design, the aluminum nitride porous ceramic is machined using ultrasonic CNC equipment to prepare an aluminum nitride porous ceramic 22 structural component that can be embedded in the aluminum nitride dense ceramic groove 202.

[0039] (3) Glaze preparation: The raw materials for preparing the glaze for aluminum nitride ceramics are mixed in a certain proportion. The components are SiO2, Al2O3, BaO and K2O, with a particle size of 1-4μm. The raw materials are weighed accurately in a certain proportion. Based on the powder mass, 15-30 parts by weight of calcium fluoride, 0.1-1 parts by weight of yttrium fluoride, 35-50 parts by weight of solvent, 0.5-3 parts by weight of binder and 0.3-1.5 parts by weight of dispersant are put into a ball mill containing 200-300 parts by weight of alumina balls with a particle size of 5-15mm. The mixture is processed at a speed of 120-150r / min for 12-24 hours to obtain a uniformly mixed granulated slurry. The solvent is one or more of ethanol, terpineol, ethyl acetate and isopropanol. The binder is polyvinyl butyral.

[0040] (4) Assembly welding: The prepared glaze is evenly coated on the upper surface of the groove 202 of the aluminum nitride dense ceramic 21. The aluminum nitride porous ceramic 22 is placed in the groove 202 of the aluminum nitride dense ceramic 21 according to the structural design to form an assembly. The assembly is placed in a drying oven and baked at 70-90℃ for 2-4 hours. After the glaze is dried, it is transferred to a high-temperature vacuum welding furnace and kept at 1000-1200℃ for 20-50 minutes. The welding is completed when the aluminum nitride porous ceramic 22 and the aluminum nitride dense ceramic 21 are combined to form the ceramic layer 20.

[0041] To better illustrate the working principle and advantages of the electrostatic-vacuum composite chuck of the present invention, two specific embodiments are provided below. However, these embodiments are merely exemplary applications of the principles of the present invention, and the scope of protection of the present invention should not be limited to these specific embodiments, but should cover all implementation methods based on the same principle, regardless of their specific form and application scenario.

[0042] Example 1 like Figure 1As shown in the figure, this embodiment discloses a specific structure of an electrostatic-vacuum composite chuck, including an aluminum nitride porous ceramic 22, an aluminum nitride dense ceramic 21, and a base 10. The aluminum nitride dense ceramic 21 has an air channel on its front side and an adsorption line 23 inside. The base 10 has a coolant flow channel inside.

[0043] Aluminum nitride dense ceramic 21 comprises the following raw materials by weight percentage: AlN 85-90%, CeO2 2-5%, YF3 2-5%, CaF2 2-5%, and Y2O3 2-5%.

[0044] The various formulations of the aluminum nitride dense ceramic 21 are shown in the table below.

[0045] Table 1. Mass percentage formulation of aluminum nitride dense ceramics 21

[0046] The aluminum nitride dense ceramic 21 used in this embodiment 1 adopts formula one.

[0047] The preparation method of the aluminum nitride dense ceramic 21 includes the following steps: (1) Slurry preparation method: The raw materials for preparing aluminum nitride dense ceramic 21 are mixed in a certain proportion. The components are AlN, CeO2, YF3, CaF2 and Y2O3, with a particle size of 0.5μm. The raw materials are weighed accurately in a certain proportion. Based on the powder mass, 45 parts by weight of solvent and 1.3 parts by weight of dispersant are added and put into a ball mill containing 200 parts by weight of alumina balls with a particle size of 5mm. The mixture is processed at a speed of 50r / min for 12 hours. Then, 7 parts by weight of binder and 5 parts by weight of plasticizer are added to the ball mill and the ball milling continues for 12 hours. The ball-milled slurry is degassed for 1.5 hours to obtain a casting slurry with a viscosity of 5000mPa.s.

[0048] (2) Casting and cutting: The degassed casting slurry is formed using a casting machine to obtain a ceramic green porcelain strip with a diameter of 0.3mm. The strip is then cut into ceramic green porcelain pieces of uniform size using a cutting machine.

[0049] (3) Printing and filling holes: After drilling holes in the ceramic raw ceramic pieces, a printing machine is used to print and fill the holes with metal paste.

[0050] (4) Stacking: After printing, the ceramic raw porcelain sheets are stacked and placed on a pad, then put into a vacuum bag for vacuum sealing. After sealing, they are placed in an isostatic press and pressed for 20 minutes at 60℃ and 10MPa to obtain ceramic raw porcelain plates.

[0051] (5) Debinding: Place the ceramic raw porcelain plate on the corundum mullite firing plate, put it into the debinding furnace, and slowly heat it to 480°C at a heating rate of 0.5°C / min. Hold it for 6 hours to obtain the ceramic debinding sheet.

[0052] (6) Sintering: The ceramic sheet is placed in a high-temperature sintering furnace and sintered at 1750℃ for 2 hours to obtain dense aluminum nitride ceramic sintered sheets.

[0053] (7) Machining: The sintered ceramic sintered sheets are machined according to the drawings using machining equipment to obtain aluminum nitride dense ceramic 21 with a flatness of <5μm and a surface roughness of <0.1μm.

[0054] The porous aluminum nitride ceramic 33 comprises the following raw materials by weight percentage: AlN 85-90%, MgF2 2-5%, YF3 2-5%, CaF2 2-5%, and Y2O3 2-5%.

[0055] The various formulations of the aluminum nitride porous ceramic 22 are shown in the table below.

[0056] Table 2. Mass percentage formulation of aluminum nitride porous ceramic 22

[0057] The porous aluminum nitride ceramic 22 used in this embodiment 1 adopts formula 2.

[0058] The preparation method of the aluminum nitride porous ceramic 22: (1) Preparation of slurry: The raw materials for preparing porous aluminum nitride ceramics are mixed in a certain proportion. The components are AlN, CeO2, YF3, CaF2 and Y2O3, with a particle size of 0.2μm. The raw materials are weighed accurately in a certain proportion. Based on the powder mass, 20 parts by weight of pore-forming agent, 15 parts by weight of calcium fluoride, 0.1 parts by weight of yttrium fluoride, 45 parts by weight of solvent and 0.5 parts by weight of dispersant are added to a ball mill containing 200 parts by weight of alumina balls with a particle size of 5mm. The mixture is processed at a speed of 40r / min for 12 hours. Then, 9 parts by weight of binder and 5 parts by weight of plasticizer are added to the ball mill, and the ball milling is continued for 12 hours to obtain a uniformly mixed granulated slurry. The pore-forming agent is one or more of polymethyl methacrylate (PMMA), carboxymethyl cellulose (CMC) and polyurethane. The particle size of the pore-forming agent is 30μm.

[0059] (2) Granulation: The mixed granulated slurry is granulated using a granulator to obtain granulated powder with a particle size of 50μm, and then sieved and batched using a vibrating screen.

[0060] (3) Dry pressing: The granulated powder is poured into the mold using a hydraulic press and aluminum nitride dry blank is obtained under a pressure of 500T.

[0061] (4) Isostatic pressing: The obtained aluminum nitride blank is vacuum sealed using a vacuum packaging machine. After sealing, it is placed in an isostatic press and pressed for 20 minutes at 70℃ and 120MPa to obtain a ceramic green porcelain plate.

[0062] (5) Sintering: The ceramic raw ceramic plate is placed in a high-temperature sintering furnace and sintered at 1600℃ for 2 hours to obtain sintered aluminum nitride porous ceramic parts.

[0063] (6) Machining: The sintered ceramic structural parts are finally processed by double-sided grinding and machining equipment to obtain aluminum nitride porous ceramic 22 with a flatness of <5μm and a surface roughness of less than 0.1μm.

[0064] The method of combining the porous aluminum nitride ceramic 22 and the dense aluminum nitride ceramic 21 in the ceramic layer 20: (1) Machining of aluminum nitride dense ceramic 21: According to the product structure design, the prepared aluminum nitride dense ceramic 21 is processed using ultrasonic CNC equipment to prepare grooves 202 that meet the design specifications and are easy to assemble, as well as air extraction holes and airflow channels for vacuuming.

[0065] (2) Machining of aluminum nitride porous ceramic 22: According to the product structure design, the prepared aluminum nitride porous ceramic 22 is processed using ultrasonic CNC equipment to prepare an aluminum nitride porous ceramic 22 structural component that can be embedded in the groove 202 of aluminum nitride dense ceramic.

[0066] (3) Glaze preparation: The raw materials for preparing the glaze for aluminum nitride ceramics are mixed in a certain proportion according to Formula 1. The components are SiO2, Al2O3, BaO and K2O, with a particle size of 1μm. The raw materials are weighed accurately in a certain proportion. Based on the powder mass, 15 parts by weight of calcium fluoride, 0.1 parts by weight of yttrium fluoride, 35 parts by weight of solvent, 0.5 parts by weight of binder and 0.3 parts by weight of dispersant are put into a ball mill containing 200 parts by weight of alumina balls with a particle size of 6mm. The mixture is processed at a speed of 120r / min for 12 hours to obtain a uniformly mixed granulated slurry. The solvent is one or more of ethanol, terpineol, ethyl acetate and isopropanol. The binder is polyvinyl butyral (PVB).

[0067] The glaze contains the following raw materials by weight percentage: SiO2 75-80%, Al2O3 5-15%, BaO 5-15%, and K2O 5-15%. Various glaze formulations are shown in the table below.

[0068] Table 4. Glaze mass percentage formula

[0069] (4) Assembly Welding: The prepared glaze is evenly applied to the upper surface of the groove 201 of the aluminum nitride dense ceramic 21. The aluminum nitride porous ceramic 22 is placed into the groove 202 of the aluminum nitride dense ceramic 21 according to the structural design. The above assembly is placed in a drying oven and baked at 70°C for 2 hours. After the glaze is dried, it is transferred to a high-temperature vacuum welding furnace and held at 1000°C for 20 minutes. The assembly of the aluminum nitride porous ceramic 22 and the aluminum nitride dense ceramic 21 is completed after welding.

[0070] The welding strength test results for different glaze formulations are as follows.

[0071] Table 5. Welding strength test results for different glaze formulations.

[0072] Example 2 As shown in the figure, this embodiment discloses a specific structure of an electrostatic-vacuum composite chuck, including an aluminum nitride dense ceramic 21, an aluminum nitride porous ceramic 22, and a base 10. The aluminum nitride dense ceramic 21 has an air channel on its front side and an adsorption line 23 inside, while the base 10 has a coolant flow channel inside.

[0073] The aluminum nitride dense ceramic 21 comprises the following raw materials by weight percentage: AlN 85-90%, CeO2 2-5%, YF3 2-5%, CaF2 2-5%, and Y2O3 2-5%.

[0074] The various formulations of the aluminum nitride dense ceramic 21 are shown in the table below.

[0075] Table 6. 21% mass percentage formulation of aluminum nitride dense ceramics

[0076] The aluminum nitride dense ceramic 21 used in this embodiment 2 adopts formula 1.

[0077] The preparation method of the aluminum nitride dense ceramic 21 includes the following steps: (1) Slurry preparation method: The raw materials for preparing aluminum nitride dense ceramics are mixed in a certain proportion. The components are AlN, CeO2, YF3, CaF2 and Y2O3, with a particle size of 0.8μm. The raw materials are weighed accurately in a certain proportion. Based on the powder mass, 48 ​​parts by weight of solvent and 2 parts by weight of dispersant are added to a ball mill containing 250 parts by weight of alumina balls with a particle size of 6mm. The mixture is processed at a speed of 65r / min for 20 hours. Then, 9 parts by weight of binder and 7 parts by weight of plasticizer are added to the ball mill. The ball milling continues for 20 hours. The ball-milled slurry is degassed for 2 hours to obtain a casting slurry with a viscosity of 6500mPa.s.

[0078] (2) Casting and cutting: The degassed casting slurry is formed using a casting machine to obtain a 0.5mm ceramic green porcelain strip, which is then cut into ceramic green porcelain pieces of uniform size by a cutting machine.

[0079] (3) Printing and filling holes: After drilling holes in the ceramic raw ceramic pieces, a printing machine is used to print and fill the holes with metal paste.

[0080] (4) Stacking: After printing, the ceramic raw porcelain sheets are stacked and placed on a pad, then put into a vacuum bag for vacuum sealing. After sealing, they are placed in an isostatic press and pressed for 20 minutes at 70℃ and 30MPa to obtain ceramic raw porcelain plates.

[0081] (5) Debinding: Place the ceramic raw porcelain plate on the corundum mullite firing plate and put it into the debinding furnace. The temperature is slowly increased to 500℃ at a heating rate of 0.8℃ / min and held for 4.5 hours to obtain the ceramic debinding sheet.

[0082] (6) Sintering: The ceramic sheet is placed into a high-temperature sintering furnace and sintered at 1850℃ for 2 hours to obtain the ceramic sintered sheet.

[0083] (7) Machining: The sintered ceramic sintered sheets are machined according to the drawings using machining equipment to obtain aluminum nitride dense ceramic 21 with a flatness of <5μm and a surface roughness of <0.1μm.

[0084] The porous aluminum nitride ceramic 22 comprises the following raw materials by weight percentage: AlN 85-90%, MgF2 2-5%, YF3 2-5%, CaF2 2-5%, and Y2O3 2-5%.

[0085] The various formulations of the aluminum nitride porous ceramic 22 are shown in the table below.

[0086] Table 7. Mass percentage formulation of aluminum nitride porous ceramics 22

[0087] The porous aluminum nitride ceramic used in Example 2 is based on Formula 3.

[0088] The preparation method of the aluminum nitride porous ceramic 22: (1) Preparation of slurry: The raw materials for preparing porous aluminum nitride ceramics are mixed in a certain proportion. The components are AlN, CeO2, YF3, CaF2 and Y2O3, with a particle size of 0.5μm. The raw materials are weighed accurately in a certain proportion. Based on the powder mass, 23 parts by weight of pore-forming agent, 30 parts by weight of calcium fluoride, 0.5 parts by weight of yttrium fluoride, 50 parts by weight of solvent and 0.7 parts by weight of dispersant are added to a ball mill containing 250 parts by weight of alumina balls with a particle size of 10mm. The mixture is processed at a speed of 50r / min for 24 hours. Then, 10 parts by weight of binder and 8 parts by weight of plasticizer are added to the ball mill, and the ball milling continues for 24 hours to obtain a uniformly mixed granulated slurry. The pore-forming agent is one or more of polymethyl methacrylate (PMMA), carboxymethyl cellulose (CMC) and polyurethane, and the particle size of the pore-forming agent is 40μm.

[0089] (2) Granulation: The mixed granulated slurry is granulated using a granulator to obtain granulated powder with a particle size of 80μm, and then sieved and batched using a vibrating screen.

[0090] (3) Dry pressing: The granulated powder is poured into the mold using a hydraulic press and aluminum nitride dry blank is obtained under a pressure of 600T.

[0091] (4) Isostatic pressing: The obtained aluminum nitride blank is vacuum sealed using a vacuum packaging machine. After sealing, it is placed in an isostatic press and pressed for 20 minutes at 75℃ and 150MPa to obtain a ceramic green porcelain plate.

[0092] (5) Sintering: The ceramic raw porcelain plate is placed into a high-temperature sintering furnace and sintered at 1750℃ for 2.5 hours to obtain sintered ceramic structural parts.

[0093] (6) Machining: The sintered ceramic structural parts are finally processed by double-sided grinding and machining equipment to obtain aluminum nitride porous ceramic 22 with a flatness of <5μm and a surface roughness of less than 0.1μm.

[0094] The following tests were conducted on the various properties of the porous aluminum nitride ceramic 22 using conventional methods. The test results are shown in the table below.

[0095] Table 8 Performance Test Table for Aluminum Nitride Porous Ceramics 22

[0096] The method of combining the porous aluminum nitride ceramic 22 and the dense aluminum nitride ceramic 21 in the ceramic layer: (1) Machining of aluminum nitride dense ceramic 21: According to the product structure design, the prepared aluminum nitride dense ceramic 21 is processed using ultrasonic CNC equipment to prepare a groove 202 structure that conforms to the design specifications and is easy to assemble, as well as a vacuum hole and air flow channel for vacuuming.

[0097] (2) Machining of aluminum nitride porous ceramic 22: According to the product structure design, aluminum nitride porous ceramic 22 prepared by ultrasonic CNC equipment is processed to prepare an aluminum nitride porous ceramic 22 structural component that can be embedded in the groove 202 of aluminum nitride dense ceramic 21.

[0098] (3) Glaze preparation: The raw materials for preparing the glaze for aluminum nitride ceramics are mixed in a certain proportion according to Formula 1. The components are SiO2, Al2O3, BaO and K2O, with a particle size of 2μm. The raw materials are accurately weighed in a certain proportion. Based on the powder mass, 20 parts by weight of calcium fluoride, 0.5 parts by weight of yttrium fluoride, 40 parts by weight of solvent, 1 part by weight of binder and 1 part by weight of dispersant are put into a ball mill containing 240 parts by weight of alumina balls with a particle size of 10mm. The mixture is processed at a speed of 140r / min for 24 hours to obtain a uniformly mixed granulated slurry. The solvent is one or more of ethanol, terpineol, ethyl acetate and isopropanol. The binder is polyvinyl butyral (PVB). The glaze contains the following raw materials in weight percentages: SiO2 75-80%, Al2O3 5-15%, BaO 5-15%, and K2O 5-15%. Various formulations of the glaze are shown in the table below.

[0099] Table 9. Glaze Mass Percentage Formulation

[0100] (4) Assembly Welding: The prepared glaze is evenly applied to the upper surface of the groove 202 of the aluminum nitride dense ceramic 21. The aluminum nitride porous ceramic 22 is placed into the groove 202 of the aluminum nitride dense ceramic 21 according to the structural design to form an assembly. The assembly is placed in a drying oven and baked at 90°C for 4 hours. After the glaze is dried, it is transferred to a high-temperature vacuum welding furnace and held at 1200°C for 30 minutes. The assembly of the aluminum nitride porous ceramic 22 and the aluminum nitride dense ceramic 21 is completed after welding.

[0101] The welding strength test results for different glaze formulations are as follows.

[0102] Table 10. Welding strength test results for different glaze formulations.

[0103] Furthermore, the electrostatic-vacuum composite chuck of Embodiments 1 and 2 has the same structural design, as shown in the figure. The electrostatic-vacuum composite chuck consists of aluminum nitride dense ceramic 21, aluminum nitride porous ceramic 22, and a base 10. The aluminum nitride porous ceramic 22 is divided into four groups embedded in the aluminum nitride dense ceramic 21. The aluminum nitride dense ceramic 21 has three evenly distributed LIFT PIN holes, an adsorption line 23 inside, an air groove on the front, and an air extraction hole penetrating the ceramic. The adsorption line 23 has positive and negative electrodes. The base 10 has a coolant flow channel, an air extraction hole, positive and negative electrode through holes, and three LIFT PIN holes.

[0104] The aluminum nitride dense ceramic 21 with built-in adsorption circuit 23 generates electrostatic force after being energized, adsorbing the workpiece, and is suitable for vacuum and plasma environments. The aluminum nitride porous ceramic 22 and aluminum nitride dense ceramic 21 are evacuated by connecting a vacuum pump through the evacuation port, generating negative pressure to adsorb the workpiece.

[0105] The key design feature of this invention is an electrostatic-vacuum composite chuck that combines the working principles of an electrostatic chuck and a vacuum chuck. The electrostatic chuck works by generating an electrostatic field in the dense aluminum nitride ceramic after energization, attracting objects. The vacuum chuck works by generating negative pressure through a connected vacuum pump, attracting objects. This electrostatic-vacuum composite chuck can simultaneously achieve the working principles of both electrostatic chucks and vacuum chucks, meaning it can initiate electrostatic and vacuum adsorption simultaneously, making it suitable for applications requiring extremely high stability and precision.

[0106] Compared to existing electrostatic chucks or vacuum chucks, the electrostatic-vacuum composite chuck of this invention combines the functions of both, replacing single-function vacuum chucks or electrostatic chucks and applicable to a wider range of process conditions. The vacuum chuck provides strong mechanical adsorption, while the electrostatic chuck provides uniform electrostatic adsorption; the combined dual adsorption force significantly improves adsorption stability. This allows a single device to meet multiple processing requirements, increasing equipment utilization.

[0107] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. An electrostatic-vacuum composite chuck, characterized in that: It includes a base and a ceramic layer; the ceramic layer is welded and fixed to the base, and the ceramic layer is composed of dense aluminum nitride ceramic and porous aluminum nitride ceramic.

2. The electrostatic-vacuum composite chuck according to claim 1, characterized in that: The aluminum nitride dense ceramic comprises the following raw materials by weight percentage: AlN 85-90%, CeO2 2-5%, YF3 2-5%, CaF2 2-5%, and Y2O3 2-5%.

3. The electrostatic-vacuum composite chuck according to claim 1, characterized in that: The porous aluminum nitride ceramic comprises the following raw materials by weight percentage: AlN 85-90%, MgF2 2-5%, YF3 2-5%, CaF2 2-5%, and Y2O3 2-5%.

4. The electrostatic-vacuum composite chuck according to claim 1, characterized in that: The aluminum nitride dense ceramic and aluminum nitride porous ceramic are welded together using a glaze, which includes the following raw materials by weight percentage: SiO2 75-90%, Al2O3 10-15%, BaO 5-10%, and K2O 5-10%.

5. The electrostatic-vacuum composite chuck according to claim 1, characterized in that: The base is provided with positive and negative adsorption electrode holes, air extraction holes, coolant inlet and outlet, and multiple LIFT PIN holes, and the base is provided with coolant flow channels.

6. The electrostatic-vacuum composite chuck according to claim 1, characterized in that: The aluminum nitride dense ceramic has pores and multiple uniformly distributed LIFT PIN holes. The aluminum nitride dense ceramic has an adsorption circuit inside. The front side of the aluminum nitride dense ceramic has a groove. The aluminum nitride dense ceramic has several vent holes that penetrate the ceramic. The adsorption circuit has a set of positive and negative electrodes.

7. The electrostatic-vacuum composite chuck according to claim 1, characterized in that: The porous aluminum nitride ceramic has pores inside, which are used to create a vacuum and negative pressure. The workpiece is fixed on the chuck surface by the pressure difference between the negative pressure generated inside the porous aluminum nitride ceramic and the atmospheric pressure.

8. The electrostatic-vacuum composite chuck according to claim 1, characterized in that: The method for preparing the aluminum nitride dense ceramic includes the following steps: (1) Slurry preparation method: The raw materials for preparing aluminum nitride dense ceramics are mixed in a certain proportion. The components are AlN, CeO2, YF3, CaF2 and Y2O3, with a particle size of 0.2-3μm. The raw materials are weighed accurately in a certain proportion. Based on the powder mass, 45-55 parts by weight of solvent and 0.5-2.5 parts by weight of dispersant are added and put into a ball mill containing 200-300 parts by weight of alumina balls with a particle size of 5-15mm. The mixture is processed at a speed of 40-70r / min for 12-24 hours. Then, 7-11 parts by weight of binder and 4-8 parts by weight of plasticizer are added to the ball mill. The ball milling is continued for 12-24 hours. The ball-milled slurry is degassed for 1-2 hours to obtain a casting slurry with a viscosity of 5000-10000mPa.s. (2) Casting and cutting: The degassed casting slurry is formed using a casting machine to obtain a ceramic green porcelain strip with a diameter of 0.3-0.6mm, which is then cut into ceramic green porcelain pieces of uniform size by a cutting machine; (3) Printing and filling holes: After drilling holes in the ceramic raw ceramic pieces, a printing press is used to print and fill the holes with metal paste; (4) Stacking: After printing, the ceramic green porcelain sheets are stacked and placed on a pad, put into a vacuum bag and vacuum sealed. After sealing, they are placed in an isostatic press and pressed for 10-30 minutes at 60-80℃ and 10-40MPa to obtain ceramic green porcelain plates. (5) Debinding: Place the ceramic raw porcelain plate on the corundum mullite firing plate, put it into the debinding furnace, and slowly heat it to 450-650℃ at a heating rate of 0.3-1℃ / min. Hold it for 3-6 hours to obtain the ceramic debinding sheet. (6) Sintering: The ceramic sheet is placed into a high-temperature sintering furnace and sintered at 1750-1850℃ for 2-4 hours to obtain the ceramic sintered sheet; (7) Machining: The sintered ceramic sheets are machined according to the drawings using machining equipment to obtain aluminum nitride dense ceramics with a flatness of <5μm and a surface roughness of <0.1μm.

9. The electrostatic-vacuum composite chuck according to claim 1, characterized in that: The method for preparing the porous aluminum nitride ceramic includes the following steps: (1) Preparation of slurry: The raw materials for preparing porous aluminum nitride ceramics are mixed in a certain proportion. The components are AlN, MgF2, YF3, CaF2 and Y2O3, with a particle size of 0.2-3μm. The raw materials are weighed accurately in a certain proportion. Based on the powder mass, 10-30 parts by weight of pore-forming agent, 15-30 parts by weight of calcium fluoride, 0.1-1 parts by weight of yttrium fluoride, 45-55 parts by weight of solvent, and 0.5-2.5 parts by weight of dispersant are added. The agent is fed into a ball mill containing 200-300 parts by weight of alumina balls with a particle size of 5-15 mm, and processed at a speed of 40-70 r / min for 12-24 hours; then 7-11 parts by weight of binder and 4-8 parts by weight of plasticizer are added to the ball mill, and ball milling is continued for 12-24 hours to obtain a uniformly mixed granulated slurry; the pore-forming agent is one or more of polymethyl methacrylate, carboxymethyl cellulose and polyurethane, and the pore-forming agent has a particle size of 30-60 μm; (2) Granulation: The mixed granulation slurry is granulated using a granulator to obtain granulated powder with a particle size of 50-100μm, and then sieved and batched using a vibrating screen; (3) Dry pressing: The granulated powder is poured into the mold using a hydraulic press and aluminum nitride dry blank is obtained under a pressure of 500T; (4) Isostatic pressing: The obtained aluminum nitride blank is vacuum sealed using a vacuum packaging machine. After sealing, it is placed in an isostatic press and pressed for 10-30 minutes at 60-80℃ and 150-200MPa to obtain a ceramic green porcelain plate. (5) Sintering: The ceramic raw porcelain plate is placed into a high-temperature sintering furnace and sintered at 1600-1850℃ for 2-4 hours to obtain sintered ceramic structural parts; (6) Machining: The sintered ceramic structural parts are finally processed by double-sided grinding and machining equipment to obtain aluminum nitride porous ceramics with a flatness of <5μm and a surface roughness of less than 0.1μm.

10. A method for preparing an electrostatic-vacuum composite chuck as described in any one of claims 1-9, characterized in that: The method for combining porous aluminum nitride ceramics and dense aluminum nitride ceramics includes the following steps: (1) Machining of aluminum nitride dense ceramics: Based on the product structure design, use ultrasonic CNC equipment to process aluminum nitride dense ceramics to prepare groove structures that meet the design specifications and facilitate assembly, as well as air extraction holes and airflow channels for vacuuming. (2) Machining of porous aluminum nitride ceramics: Based on the product structure design, porous aluminum nitride ceramics are machined using ultrasonic CNC equipment to prepare porous aluminum nitride ceramic structural parts that can be embedded in the grooves of dense aluminum nitride ceramics. (3) Glaze preparation: The raw materials for preparing the glaze for aluminum nitride ceramics are mixed in a certain proportion. The components are SiO2, Al2O3, BaO, and K2O, with a particle size of 1-4μm. The raw materials are weighed accurately in a certain proportion. Based on the powder mass, 15-30 parts by weight of calcium fluoride, 0.1-1 parts by weight of yttrium fluoride, 35-50 parts by weight of solvent, 0.5-3 parts by weight of binder, and 0.3-1.5 parts by weight of dispersant are put into a ball mill containing 200-300 parts by weight of alumina balls with a particle size of 5-15mm. The mixture is processed at a speed of 120-150r / min for 12-24 hours to obtain a uniformly mixed granulated slurry. The solvent is one or more of ethanol, terpineol, ethyl acetate, and isopropanol. The binder is polyvinyl butyral. (4) Assembly welding: The prepared glaze is evenly coated on the upper surface of the groove wall of the aluminum nitride dense ceramic. The aluminum nitride porous ceramic is placed in the groove of the aluminum nitride dense ceramic according to the structural design to form an assembly. The assembly is placed in a drying oven and baked at 70-90℃ for 2-4 hours. After the glaze is dried, it is transferred to a high-temperature vacuum welding furnace and kept at 1000-1200℃ for 20-50 minutes. The combination of aluminum nitride porous ceramic and aluminum nitride dense ceramic to form a ceramic layer is completed after welding.

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