Electrostatic chuck base and welding method thereof

Abstract

The electrostatic chuck base comprises a base body provided with a cavity with an upward opening, a vortex-shaped guide plate arranged at the bottom of the cavity, a vortex-shaped cooling groove formed between the guide plate and the cavity, and a soldering lug groove formed in the upper end face of the guide plate and extending in the length direction of the guide plate; the cover plate covers the guide plate and forms a cooling flow channel with the cooling groove, and a gap is formed between the upper end face of the guide plate located on the inner side of the soldering lug groove and the cover plate; and the soldering lug is arranged in the soldering lug groove, the thickness of the soldering lug is the same as the depth of the soldering lug groove, the soldering lug is heated and melted, and the melted soldering lug fills the gap through the capillary action. According to the scheme, the connecting strength of the cover plate on the base body is improved, and the problems that in the welding and heating process of the base, the cover plate warps to cause liquid mixing of a cooling flow channel in the base and the cover plate swells to affect the flatness of the base under the condition that the cooling flow channel is pressed for a long time are solved.

Description

Technical Field

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

[0002] An electrostatic chuck is an ultra-clean wafer carrier suitable for vacuum and plasma environments. It utilizes electrostatic adsorption to clamp ultra-thin wafers evenly and smoothly. Its key function is to adsorb silicon wafers, glass, and various masks, ensuring excellent flatness during processing and effectively suppressing deformation. An electrostatic chuck typically consists of three core components: an insulating layer, a heater, and a base. The base, as one of the main core components, directly affects the overall performance and quality of the electrostatic chuck.

[0003] Currently, the manufacturing technology of electrostatic chuck bases in China is not stable enough in the welding process of base cooling channels (due to issues such as liquid cross-contamination between channels), especially for large-size bases, where traditional welding processes struggle to solve the problem of liquid cross-contamination between channels. With the development of next-generation semiconductor technology, processes such as low-temperature etching and deposition typically require wafers to reach even lower temperatures, thus placing higher demands on the heat dissipation performance of electrostatic chucks. Therefore, the first step is to solve the problem of unstable welding processes for base cooling channels to improve cooling and heat dissipation performance.

[0004] The existing electrostatic chuck base is welded to the base body by electron beam welding or friction stir welding, where the outer peripheral wall of the cover plate is welded to the base body. During the welding process, large bases deform due to heat, causing the cover plate to warp and create a large gap between it and the base body, resulting in liquid leakage in the cooling channel. Furthermore, since there is no welding between the lower end face of the cover plate and the base body, and some cover plates are relatively thin, the cover plate is prone to bulging outward under long-term pressure in the cooling channel, leading to problems such as liquid leakage in the base cooling channel and poor flatness of the base.

[0005] For example, Chinese Patent Publication No. CN118588624A, published on September 3, 2024, entitled "A Cooling and Heating Dual-Functional Electrostatic Chuck Base", includes a base body, a cooling channel is provided in the base body, and several heating elements are installed on the base body.

[0006] The drawbacks of existing patents are as follows: The welding of existing electrostatic chuck bases involves welding the outer peripheral wall of the cover plate to the base body using electron beam welding or friction stir welding. During the welding process, large-sized bases deform due to heat, causing the cover plate to warp and create a large gap between it and the base body, resulting in liquid leakage in the cooling channel. Furthermore, since there is no welding between the lower end face of the cover plate and the base body, and some cover plates are relatively thin, the cover plate is prone to bulging outward under long-term pressure in the cooling channel, leading to liquid leakage in the base cooling channel and poor flatness of the base. Summary of the Invention

[0007] The purpose of this invention is to improve the existing electrostatic chuck base welding method, which involves welding the outer peripheral wall of the cover plate to the base body using electron beam welding or friction stir welding. This method addresses the problems of heat deformation during welding and long-term pressure on the cooling channels within the base, which can lead to liquid cross-contamination in the cooling channels and poor base flatness. The invention provides an electrostatic chuck base that prevents liquid cross-contamination in the cooling channels and ensures base flatness, along with its welding method.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: An electrostatic chuck base, comprising: The base body has an upward-opening cavity, and a vortex-shaped guide plate is provided at the bottom of the cavity. A vortex-shaped cooling groove is formed between the guide plate and the cavity. A welding plate groove extending along the length of the guide plate is provided on the upper surface of the guide plate. A cover plate is placed between the guide plate and the cooling tank to form a cooling flow channel. A gap is provided between the upper surface of the guide plate located inside the welding plate groove and the cover plate. A brazed sheet is placed in a weld bar groove, the thickness of which is the same as the groove depth. The brazed sheet melts upon heating, and the melted sheet fills the gaps through capillary action. In this technical solution, the electrostatic chuck base includes a base body and a cover plate placed on the base body. A brazed sheet is placed between the base body and the cover plate. The lower end face of the cover plate and the upper end face of the inner guide plate of the base body are brazed together, and the outer peripheral wall of the cover plate and the inner peripheral wall of the base body are welded together using electron beam welding. This improves the connection strength of the cover plate to the base body and prevents the cover plate from warping during the heating process, which could cause cross-contamination of the cooling channels within the base. Specifically, by brazing the lower end face of the cover plate and the upper end face of the inner guide plate of the base body, the connection strength between the lower end face of the cover plate and the base body is improved. Under long-term pressure in the cooling channels within the base, the middle of the cover plate will not bulge significantly outwards, ensuring good flatness of the base, excellent flatness of the electrostatic chuck, and overall performance quality of the electrostatic chuck.

[0009] The upper surface of the guide plate is provided with a brazing tab groove extending along the length of the guide plate. Brazing tabs are placed in the brazing tab groove, and the thickness of the brazing tab is the same as the groove depth. This prevents excessive flow of the molten brazing tab into the cooling channel, where it can cool and form nodules or sheet-like blockages, reducing the effective flow area, increasing flow resistance, or even completely blocking part of the local flow channel. In this technical solution, the thickness of the brazing tab is the same as the groove depth, preventing excessive flow of the molten brazing tab into the cooling channel. The upper surface of the guide plate, located outside the brazing tab groove, abuts against the cover plate, positioning the brazing tab and preventing it from flowing into the cooling channel after melting. Simultaneously, the brazed sheet expands upon heating and melting. Due to the gap between the upper surface of the guide plate located inside the brazed sheet groove and the cover plate, the brazed sheet, driven by the surface energy of the solid, causes the leading edge of the brazing filler metal to push the gas in the gap outward. This fills the gap through capillary action, preventing excessive brazed sheet overflow while increasing the welding area between the cover plate and the guide plate, enhancing the welding strength of the cover plate, and preventing problems such as cover plate warping or bulging. The brazed sheet welds the weld seam through capillary action, utilizing the excellent wettability of liquid metal on the clean base material surface to generate a strong capillary driving force in the micron-level gap, thereby achieving a precise connection process of orientation, self-filling, and ultimately metallurgical bonding.

[0010] Preferably, the base body is provided with an inlet and an outlet. The inlet connects one end of the cooling tank and the lower end face of the base body, and the outlet connects the other end of the cooling tank and the lower end face of the base body. The inlet and outlet are respectively located at both ends of the vortex-shaped cooling channel.

[0011] Preferably, the bottom of the solder pad groove is provided with a fine hole, which connects the solder pad groove and the lower end face of the base body. The fine hole at the bottom of the solder pad groove serves two purposes: firstly, it releases stress, guiding the welding stress to be released in an area that does not affect the flow channel; secondly, it also generates a certain capillary effect within the fine hole, preventing the brazed solder pad from overflowing into the cooling flow channel.

[0012] Preferably, there are multiple micro-holes distributed along the length of the weld spatula. The irregular distribution of these micro-holes along the length of the weld spatula serves to release stress, guiding the welding stress towards areas that do not affect the flow channel.

[0013] Preferably, the upper surface of the cover plate is flush with the upper surface of the base body, and the outer peripheral wall of the cover plate mates with the inner sidewall of the base body. The cover plate is placed on the guide plate, ensuring that the upper surface of the cover plate is flush with the upper surface of the base body, guaranteeing good flatness of the base, excellent flatness of the electrostatic chuck, and overall performance quality of the electrostatic chuck.

[0014] Preferably, the brazed sheet mates with the sheet groove, and the brazed sheet extends along the length of the guide plate.

[0015] A welding method for an electrostatic chuck base includes the following steps: Step 1: Before welding, install the base body, brazing sheet and cover plate in sequence; Step 2: First, weld the lower end face of the cover plate to the base body using vacuum brazing; Step 3: Then, the outer peripheral wall of the cover plate is welded to the base body by electron beam welding.

[0016] This welding method involves brazing the lower end face of the cover plate to the upper end face of the inner guide plate of the base body, and electron beam welding the outer peripheral wall of the cover plate to the inner peripheral wall of the base body. This improves the connection strength between the cover plate and the base body, preventing the cover plate from warping during the welding heating process and causing liquid leakage in the cooling channels within the base. Specifically, by brazing the lower end face of the cover plate to the upper end face of the inner guide plate of the base body, the connection strength between the lower end face of the cover plate and the base body is improved. Even under long-term pressure in the cooling channels within the base, the middle of the cover plate will not bulge significantly outward, ensuring good flatness of the base, excellent flatness of the electrostatic chuck, and overall performance quality of the electrostatic chuck.

[0017] Preferably, in step 2, the installed base is clamped and placed into the brazing furnace; after closing the door, the furnace is evacuated to 5 x 10⁻³ Pa; the initial temperature is raised to 360°C for 60 minutes and held for 10 minutes, then raised to 550°C for 30 minutes and held for 10 minutes, then raised to 570°C for 20 minutes and held for 70 minutes, then raised to 590°C for 10 minutes and held for 20 minutes; finally, the temperature is lowered to below 60°C for 60 minutes, the pressure is released, the furnace is opened, and the vacuum brazing is completed, and the base is removed. In this technical solution, the lower end face of the cover plate and the upper end face of the guide plate are brazed. The temperature is gradually raised and held in stages in the brazing furnace. By precisely controlling the heat input, the workpiece is ensured to be heated evenly, the material is transformed smoothly, and the brazing filler metal flows correctly. Finally, the base obtains a high-quality vortex-shaped cooling channel that is free from blockages, leaks, stress, and has a complete shape. Gradual heating allows the brazing filler metal to melt smoothly and its viscosity to decrease gradually, thus flowing into the gap at a controllable speed. This prevents the brazing filler metal from entering the cooling channel too quickly and forming nodules or sheet-like blockages after cooling, which can reduce the effective flow area, increase flow resistance, or even completely block part of the local flow channel.

[0018] Preferably, in step 3, the base is fixed on the vacuum electron beam welding workbench; after determining the working distance, the door is closed, and the vacuum chamber is evacuated to 5x10⁻⁵ mbr; tack welding with a penetration depth of 1 mm is performed sequentially, followed by sealing welding with a penetration depth of 2 mm, main welding with a penetration depth of 9 mm, and finishing welding with a penetration depth of 2.5 mm; after depressurization, the vacuum chamber is opened, the weld is inspected, and the base is removed. Electron beam welding involves tack welding, sealing welding, main welding, and finishing welding in sequence. Tack welding ensures precise positioning and prevents misalignment; sealing welding forms a sealed microcavity to prevent explosion; main welding achieves deep penetration of the main weld; and finishing welding enhances the shape and eliminates defects, thereby obtaining a high-quality base.

[0019] Preferably, before step 1, the base body and cover plate to be welded are chemically cleaned and packaged. The packaging is opened and the base is installed before welding. During installation, clean latex gloves should be worn to avoid product contamination before welding. The cleanliness of the base body and cover plate ensures a high weld pass rate.

[0020] The beneficial effects of this invention are as follows: By brazing the lower end face of the cover plate and the upper end face of the inner guide plate of the base body, and by electron beam welding the outer peripheral wall of the cover plate and the inner peripheral wall of the base body, the connection strength of the cover plate on the base body is improved, preventing the cover plate from warping during the welding heating process and causing liquid leakage in the cooling channel inside the base; wherein, by brazing the lower end face of the cover plate and the upper end face of the inner guide plate of the base body, the connection strength between the lower end face of the cover plate and the base body is improved, and under long-term pressure in the cooling channel inside the base, the middle part of the cover plate will not bulge outward significantly, ensuring good flatness of the base, ensuring excellent flatness of the electrostatic chuck, and ensuring the performance quality of the entire electrostatic chuck. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of one structure of the present invention.

[0022] Figure 2 This is a schematic diagram of the structure of the base body in this invention.

[0023] Figure 3 This is a cross-sectional view of the present invention.

[0024] Figure 4 This is a partially enlarged cross-sectional view of the present invention.

[0025] As shown in the picture: Base body 1, Inlet 1.1, Outlet 1.2, Guide plate 2, weld plate groove 2.1, fine hole 2.1.1, gap 2.2, 3. Cover plate; 4. Cooling channel; 5. Brazing sheet. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0027] Example 1, as Figure 1 , Figure 2 , Figure 3 , Figure 4 An electrostatic chuck base is shown, comprising: a base body 1, having an upward-opening cavity, a vortex-shaped guide plate 2 at the bottom of the cavity, a vortex-shaped cooling groove formed between the guide plate 2 and the cavity, and a solder pad groove 2.1 extending along the length of the guide plate 2 on the upper end face; a cover plate 3, covering the guide plate 2 and forming a cooling channel 4 between it and the cooling groove, with a gap 2.2 between the upper end face of the guide plate 2 located inside the solder pad groove 2.1 and the cover plate 3; and a brazed solder pad 5, placed in the solder pad groove 2.1, the thickness of the brazed solder pad 5 being the same as the groove depth of the solder pad groove 2.1, the brazed solder pad 5 being heated and melted, and the melted brazed solder pad 5 filling the gap 2.2 through capillary action.

[0028] An electrostatic chuck is an ultra-clean wafer carrier suitable for vacuum and plasma environments. It utilizes electrostatic adsorption to clamp ultra-thin wafers evenly and smoothly. Its key function is to adsorb silicon wafers, glass, and various masks, ensuring excellent flatness during processing and effectively suppressing deformation. An electrostatic chuck typically consists of three core components: an insulating layer, a heater, and a base. The base, as one of the main core components, directly affects the overall performance and quality of the electrostatic chuck.

[0029] Currently, the manufacturing technology of electrostatic chuck bases in China is not stable enough in the welding process of the base cooling channel 4 (there are problems such as liquid cross-contamination between channels), especially for large-size bases, where traditional welding processes struggle to solve the problem of liquid cross-contamination between channels. With the development of next-generation semiconductor technology, processes such as low-temperature etching and deposition typically require wafers to reach even lower temperatures, thus placing higher demands on the heat dissipation performance of electrostatic chucks. Therefore, the first step is to solve the unstable welding process of the base cooling channel 4 to improve cooling and heat dissipation performance.

[0030] Existing electrostatic chuck bases are welded by electron beam welding or friction stir welding to attach the outer peripheral wall of the cover plate 3 to the base body 1. During welding, large bases deform due to heat, causing the cover plate 3 to warp and create a large gap between it and the base body 1, leading to liquid leakage in the cooling channels 4. Furthermore, because the lower end face of the cover plate 3 is not welded to the base body 1, and some parts of the cover plate 3 are thin, it is prone to bulging outwards under long-term pressure in the cooling channels 4, resulting in liquid leakage in the cooling channels 4 and poor base flatness. To improve upon the existing electrostatic chuck base welding method, which uses electron beam welding or friction stir welding to attach the outer peripheral wall of the cover plate 3 to the base body 1, and addresses the problems of heat deformation during welding and long-term pressure in the cooling channels 4, resulting in liquid leakage in the cooling channels 4 and poor base flatness, this paper provides an electrostatic chuck base that prevents liquid leakage in the cooling channels 4 and ensures base flatness, along with its welding method.

[0031] In this embodiment, as Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, a brazing sheet 5 is provided between the base body 1 and the cover plate 3. The lower end face of the cover plate 3 and the upper end face of the inner guide plate 2 of the base body 1 are brazed together, and the outer peripheral wall of the cover plate 3 and the inner peripheral wall of the base body 1 are welded together by electron beam welding. This improves the connection strength of the cover plate 3 to the base body 1 and prevents the cover plate 3 from warping during the welding heating process, which could cause liquid leakage in the cooling channel 4 inside the base. In particular, by brazing the lower end face of the cover plate 3 and the upper end face of the inner guide plate 2 of the base body 1, the connection strength between the lower end face of the cover plate 3 and the base body 1 is improved. Under long-term pressure in the cooling channel 4 inside the base, the middle of the cover plate 3 will not bulge outward significantly, ensuring good flatness of the base, excellent flatness of the electrostatic chuck, and overall performance quality of the electrostatic chuck.

[0032] like Figure 1 , Figure 2 , Figure 3 , Figure 4As shown, the upper surface of the guide plate 2 is provided with a solder groove 2.1 extending along the length of the guide plate 2. The brazed solder sheet 5 is placed in the solder groove 2.1. The thickness of the brazed solder sheet 5 is the same as the depth of the solder groove 2.1 to prevent the brazed solder sheet 5 from flowing into the cooling channel 4 after heating and melting, forming nodular or sheet-like blockages after cooling, which would reduce the effective flow area, increase flow resistance, or even completely block part of the local flow channel. In this technical solution, the thickness of the brazed solder sheet 5 is the same as the depth of the solder groove 2.1. The brazed solder sheet 5 will not flow into the cooling channel 4 in excess after heating and melting. The upper surface of the guide plate 2, located outside the solder groove 2.1, abuts against the cover plate 3, which serves to position the brazed solder sheet 5 and prevent the brazed solder sheet 5 from flowing into the cooling channel 4 after heating and melting. Simultaneously, the brazed sheet 5, after being heated and melted, expands due to thermal expansion. Because a gap 2.2 exists between the upper surface of the guide plate 2 located inside the sheet groove 2.1 and the cover plate 3, the brazed sheet 5, driven by solid surface energy, has its brazing filler metal tip pushing the gas in the gap 2.2 outwards. This fills the gap 2.2 through capillary action, preventing excessive overflow of the brazed sheet 5 while increasing the welding area between the cover plate 3 and the guide plate 2, enhancing the welding strength of the cover plate 3, and preventing problems such as warping or bulging of the cover plate 3. The brazed sheet 5 welds the weld seam through capillary action, utilizing the excellent wettability of liquid metal on the clean base material surface to generate a strong capillary driving force in the micron-level gap 2.2, thereby achieving a precise connection process of orientation, self-filling, and ultimately metallurgical bonding.

[0033] Specifically, such as Figure 2 , Figure 3 As shown, the base body 1 is provided with an inlet 1.1 and an outlet 1.2. The inlet 1.1 connects one end of the cooling tank and the lower end face of the base body 1, and the outlet 1.2 connects the other end of the cooling tank and the lower end face of the base body 1. The inlet 1.1 and the outlet 1.2 are respectively located at both ends of the vortex-shaped cooling channel 4.

[0034] Further optimizations were made to cover plate 3, such as... Figure 1 , Figure 3 , Figure 4 As shown, the upper surface of the cover plate 3 is flush with the upper surface of the base body 1, and the outer peripheral wall of the cover plate 3 fits with the inner side wall of the base body 1. The cover plate 3 is placed on the guide plate 2, ensuring that the upper surface of the cover plate 3 is flush with the upper surface of the base body 1, ensuring good flatness of the base, ensuring excellent flatness of the electrostatic chuck, and ensuring the overall performance quality of the electrostatic chuck.

[0035] like Figure 1 , Figure 2 , Figure 3 , Figure 4As shown, the welding method of the electrostatic chuck base in this embodiment includes the following steps in sequence: Step 1: Before welding, install the base body 1, brazing sheet 5 and cover plate 3 in sequence; Step 2: First, weld the lower end face of the cover plate 3 to the base body 1 by vacuum brazing; Step 3: Then, weld the outer peripheral wall of the cover plate 3 to the base body 1 by electron beam welding.

[0036] Example 2, as Figure 1 , Figure 2 , Figure 3 , Figure 4 An electrostatic chuck base is shown, comprising: a base body 1, having an upward-opening cavity, a vortex-shaped guide plate 2 at the bottom of the cavity, a vortex-shaped cooling groove formed between the guide plate 2 and the cavity, and a solder pad groove 2.1 extending along the length of the guide plate 2 on the upper end face; a cover plate 3, covering the guide plate 2 and forming a cooling channel 4 between it and the cooling groove, with a gap 2.2 between the upper end face of the guide plate 2 located inside the solder pad groove 2.1 and the cover plate 3; and a brazed solder pad 5, placed in the solder pad groove 2.1, the thickness of the brazed solder pad 5 being the same as the groove depth of the solder pad groove 2.1, the brazed solder pad 5 being heated and melted, and the melted brazed solder pad 5 filling the gap 2.2 through capillary action.

[0037] Specifically, such as Figure 2 , Figure 3 As shown, the base body 1 is provided with an inlet 1.1 and an outlet 1.2. The inlet 1.1 connects one end of the cooling tank and the lower end face of the base body 1, and the outlet 1.2 connects the other end of the cooling tank and the lower end face of the base body 1. The inlet 1.1 and the outlet 1.2 are respectively located at both ends of the vortex-shaped cooling channel 4.

[0038] In this embodiment, as Figure 2 , Figure 3 , Figure 4As shown, the bottom of the welding plate groove 2.1 is provided with a fine hole 2.1.1, which connects the welding plate groove 2.1 and the lower end face of the base body 1. The lower end face of the cover plate 3 and the upper end face of the inner guide plate 2 of the base body 1 are brazed, and the outer peripheral wall of the cover plate 3 and the inner peripheral wall of the base body 1 are welded by electron beam welding. This improves the connection strength of the cover plate 3 on the base body 1 and prevents the cover plate 3 from warping during the welding heating process, which could cause liquid leakage in the cooling channel 4 inside the base. In particular, by brazing the lower end face of the cover plate 3 and the upper end face of the inner guide plate 2 of the base body 1, the connection strength between the lower end face of the cover plate 3 and the base body 1 is improved. Under long-term pressure in the cooling channel 4 inside the base, the middle of the cover plate 3 will not bulge outward significantly, ensuring good flatness of the base, excellent flatness of the electrostatic chuck, and overall performance quality of the electrostatic chuck. The bottom of the brazing pad groove 2.1 is provided with a fine hole 2.1.1. On the one hand, the fine hole 2.1.1 plays a role in stress release, guiding the welding stress to be released to the area that does not affect the flow channel; on the other hand, a certain capillary effect will also be generated in the fine hole 2.1.1 to prevent the brazing pad 5 from overflowing into the cooling flow channel 4.

[0039] like Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, the upper surface of the guide plate 2 is provided with a solder groove 2.1 extending along the length of the guide plate 2. The brazed solder sheet 5 is placed in the solder groove 2.1. The thickness of the brazed solder sheet 5 is the same as the depth of the solder groove 2.1 to prevent the brazed solder sheet 5 from flowing into the cooling channel 4 after heating and melting, forming nodular or sheet-like blockages after cooling, which would reduce the effective flow area, increase flow resistance, or even completely block part of the local flow channel. In this technical solution, the thickness of the brazed solder sheet 5 is the same as the depth of the solder groove 2.1. The brazed solder sheet 5 will not flow into the cooling channel 4 in excess after heating and melting. The upper surface of the guide plate 2, located outside the solder groove 2.1, abuts against the cover plate 3, which serves to position the brazed solder sheet 5 and prevent the brazed solder sheet 5 from flowing into the cooling channel 4 after heating and melting. Simultaneously, the brazed sheet 5 expands due to heat after heating and melting. Since there is a gap 2.2 between the upper end face of the guide plate 2 located inside the sheet groove 2.1 and the cover plate 3, the brazed sheet 5, after heating and melting, will have the front edge of the brazing filler metal push the gas in the gap 2.2 outward under the drive of solid surface energy. The gas will fill the gap 2.2 through capillary action, preventing excessive brazed sheet 5 from overflowing, while increasing the welding area between the cover plate 3 and the guide plate 2, enhancing the welding strength of the cover plate 3, and preventing the cover plate 3 from warping or bulging.

[0040] Further optimizations were made to the fine pore design in version 2.1.1, such as... Figure 2 , Figure 3 , Figure 4As shown, there are multiple fine holes 2.1.1, which are distributed along the length of the weld groove 2.1. The irregular distribution of these fine holes along the length of the weld groove 2.1.1 serves to release stress, guiding the welding stress to areas that do not affect the flow channel.

[0041] Further optimizations were made to cover plate 3, such as... Figure 1 , Figure 3 , Figure 4 As shown, the upper surface of the cover plate 3 is flush with the upper surface of the base body 1, and the outer peripheral wall of the cover plate 3 fits with the inner side wall of the base body 1. The cover plate 3 is placed on the guide plate 2, ensuring that the upper surface of the cover plate 3 is flush with the upper surface of the base body 1, ensuring good flatness of the base, ensuring excellent flatness of the electrostatic chuck, and ensuring the overall performance quality of the electrostatic chuck.

[0042] To improve the welding of existing electrostatic chuck bases, where the outer peripheral wall of the cover plate 3 is welded to the base body 1 using electron beam welding or friction stir welding, problems arise due to the large size of the base. These problems include heat deformation during welding and long-term pressure on the cooling channels 4 within the base, leading to liquid cross-contamination in the cooling channels 4 and poor base flatness. Therefore, this paper provides an electrostatic chuck base that prevents liquid cross-contamination in the cooling channels 4 and ensures the flatness of the base, along with its welding method. This welding method is as follows: Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, the lower end face of the cover plate 3 and the upper end face of the inner guide plate 2 of the base body 1 are brazed together, and the outer peripheral wall of the cover plate 3 and the inner peripheral wall of the base body 1 are welded together by electron beam welding. This improves the connection strength of the cover plate 3 on the base body 1 and prevents the cover plate 3 from warping during the welding heating process, which could cause liquid leakage in the cooling channel 4 inside the base. In particular, by brazing the lower end face of the cover plate 3 and the upper end face of the inner guide plate 2 of the base body 1, the connection strength between the lower end face of the cover plate 3 and the base body 1 is improved. Under long-term pressure in the cooling channel 4 inside the base, the middle of the cover plate 3 will not bulge outward significantly, ensuring good flatness of the base, excellent flatness of the electrostatic chuck, and overall performance quality of the electrostatic chuck.

[0043] Example 3, as Figure 1 , Figure 2 , Figure 3 , Figure 4 The welding method for an electrostatic chuck base shown includes the following steps in sequence: Step 1: Before welding, install the base body 1, brazing sheet 5 and cover plate 3 in sequence; Step 2: First, weld the lower end face of the cover plate 3 to the base body 1 by vacuum brazing; Step 3: Then, the outer peripheral wall of the cover plate 3 is welded to the base body 1 by electron beam welding.

[0044] This welding method is as follows: Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, the lower end face of the cover plate 3 and the upper end face of the inner guide plate 2 of the base body 1 are brazed together, and the outer peripheral wall of the cover plate 3 and the inner peripheral wall of the base body 1 are welded together by electron beam welding. This improves the connection strength of the cover plate 3 to the base body 1 and prevents the cover plate 3 from warping during the welding heating process, which could cause liquid leakage in the cooling channel 4 inside the base. Specifically, by brazing the lower end face of the cover plate 3 and the upper end face of the inner guide plate 2 of the base body 1, the connection strength between the lower end face of the cover plate 3 and the base body 1 is improved. Under long-term pressure in the cooling channel 4 inside the base, the middle of the cover plate 3 will not bulge significantly outward, ensuring good flatness of the base, excellent flatness of the electrostatic chuck, and overall performance quality of the electrostatic chuck.

[0045] Step 2 is further optimized by clamping the installed base into the brazing furnace; after closing the door, the furnace is evacuated to 5 x 10⁻³ Pa; the initial temperature is increased to 360°C for 60 minutes and held for 10 minutes, then increased to 550°C for 30 minutes and held for 10 minutes, then increased to 570°C for 20 minutes and held for 70 minutes, then increased to 590°C for 10 minutes and held for 20 minutes; finally, the temperature is reduced to below 60°C for 60 minutes, the pressure is released, the furnace is opened, and the vacuum brazing is completed, and the base is removed. In this technical solution, the lower end face of the cover plate 3 and the upper end face of the guide plate 2 are brazed. The temperature is gradually increased and held in stages in the brazing furnace. By precisely controlling the heat input, the workpiece is ensured to be heated evenly, the material is transformed smoothly, and the brazing filler metal flows correctly. Finally, the base obtains a high-quality vortex-shaped cooling channel 4 that is unblocked, leak-free, low-stress, and has a complete shape. Gradual heating allows the brazing filler metal to melt smoothly and its viscosity to decrease gradually, thus flowing into the gap 2.2 at a controllable speed. This prevents the brazing filler metal from entering the cooling channel 4 too quickly and forming nodule-like or sheet-like blockages after cooling, which would reduce the effective flow area, increase flow resistance, or even completely block part of the local flow channel.

[0046] Step 3 was further optimized by fixing the base on the vacuum electron beam welding workbench; after determining the working distance, the door was closed, and the vacuum chamber was evacuated to 5x10⁻⁵ mbr; spot welding was performed sequentially with a weld penetration depth of 1 mm (working distance 450 mm, high voltage 90 KV, focusing current upward diffusion 5 mA, beam current 6 mA), and sealing welding with a weld penetration depth of 2 mm (working distance 450 mm, high voltage 90 KV, focusing current upward diffusion 5 mA, beam current 12 mA, welding speed 1000 mm / min, scanning amplitude 0.3x0). 9) The formal welding penetration depth is 9mm (working distance 450mm, high voltage 90KV, focusing current upward diffusion 10mA, beam current 36mA, welding speed 1000mm / min, scanning amplitude 0.3x0.9), and the finishing welding penetration depth is 2.5mm (working distance 450mm, high voltage 90KV, focusing current upward diffusion 30mA, beam current 15mA, welding speed 800mm / min, scanning amplitude 0.3x1.2). After depressurization, the vacuum chamber is opened, the weld is inspected, and the base is removed. Electron beam welding is performed sequentially by spot welding, sealing welding, formal welding, and finishing welding. Spot welding ensures precise positioning and prevents misalignment, sealing welding forms a sealed microcavity to prevent explosion-proof spraying, formal welding completes the deep penetration of the main weld, and finishing welding beautifies the shape and eliminates defects, thereby obtaining a high-quality base.

[0047] Step 1 is further optimized. Before step 1, the base body 1 and cover plate 3 to be welded are chemically cleaned and packaged. The packaging is opened and installed before welding the base. During installation, clean latex gloves must be worn to avoid product contamination before welding. The cleanliness of the base body 1 and cover plate 3 ensures a high welding pass rate.

[0048] To improve the welding of existing electrostatic chuck bases, where the outer peripheral wall of the cover plate 3 is welded to the base body 1 using electron beam welding or friction stir welding, problems arise due to the large size of the base. These problems include heat deformation during welding and long-term pressure on the cooling channels 4 within the base, leading to liquid cross-contamination in the cooling channels 4 and poor base flatness. Therefore, this paper provides an electrostatic chuck base that prevents liquid cross-contamination in the cooling channels 4 and ensures the flatness of the base, along with its welding method. This welding method is as follows: Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, the lower end face of the cover plate 3 and the upper end face of the inner guide plate 2 of the base body 1 are brazed together, and the outer peripheral wall of the cover plate 3 and the inner peripheral wall of the base body 1 are welded together by electron beam welding. This improves the connection strength of the cover plate 3 on the base body 1 and prevents the cover plate 3 from warping during the welding heating process, which could cause liquid leakage in the cooling channel 4 inside the base. In particular, by brazing the lower end face of the cover plate 3 and the upper end face of the inner guide plate 2 of the base body 1, the connection strength between the lower end face of the cover plate 3 and the base body 1 is improved. Under long-term pressure in the cooling channel 4 inside the base, the middle of the cover plate 3 will not bulge outward significantly, ensuring good flatness of the base, excellent flatness of the electrostatic chuck, and overall performance quality of the electrostatic chuck.

[0049] The specific embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the invention. All equivalent variations made in accordance with the shape and structure of the present invention should be included within the scope of protection of the present invention.

Claims

1. An electrostatic chuck base, characterized in that, include: The base body has an upward-opening cavity, and a vortex-shaped guide plate is provided at the bottom of the cavity. A vortex-shaped cooling groove is formed between the guide plate and the cavity. A welding plate groove extending along the length of the guide plate is provided on the upper surface of the guide plate. A cover plate is placed between the guide plate and the cooling tank to form a cooling flow channel. A gap is provided between the upper surface of the guide plate located inside the welding plate groove and the cover plate. The brazing sheet is placed in the brazing sheet groove, and the thickness of the brazing sheet is the same as the depth of the brazing sheet groove. The brazing sheet is heated and melted, and the melted brazing sheet fills the gap through capillary action.

2. The electrostatic chuck base according to claim 1, characterized in that, The base body is provided with an inlet and an outlet. The inlet connects one end of the cooling tank and the lower end face of the base body, and the outlet connects the other end of the cooling tank and the lower end face of the base body.

3. The electrostatic chuck base according to claim 2, characterized in that, The bottom of the welding strip groove is provided with a fine hole, which connects the welding strip groove and the lower end face of the base body.

4. The electrostatic chuck base according to claim 3, characterized in that, The number of fine holes is multiple, and the multiple fine holes are distributed along the length direction of the solder pad groove.

5. An electrostatic chuck base according to claim 1, 2, 3, or 4, characterized in that, The upper surface of the cover plate is flush with the upper surface of the base body, and the outer peripheral wall of the cover plate fits into the inner side wall of the base body.

6. An electrostatic chuck base according to claim 1, 2, 3, or 4, characterized in that, The brazed sheet mates with the sheet groove, and the brazed sheet extends along the length of the guide plate.

7. A welding method for an electrostatic chuck base according to any one of claims 1-6, characterized in that, The steps are as follows: Step 1: Before welding, install the base body, brazing sheet and cover plate in sequence; Step 2: First, weld the lower end face of the cover plate to the base body using vacuum brazing; Step 3: Then, the outer peripheral wall of the cover plate is welded to the base body by electron beam welding.

8. The welding method for an electrostatic chuck base according to claim 7, characterized in that, In step 2, the installed base is clamped and placed into the brazing furnace; after closing the door, the furnace is evacuated to 5 x 10⁻³ Pa; the temperature is initially raised to 360°C for 60 minutes and held for 10 minutes, then raised to 550°C for 30 minutes and held for 10 minutes, then raised to 570°C for 20 minutes and held for 70 minutes, then raised to 590°C for 10 minutes and held for 20 minutes; finally, the temperature is lowered to below 60°C for 60 minutes, the pressure is released, the furnace is opened to complete the vacuum brazing, and the base is removed.

9. The welding method for an electrostatic chuck base according to claim 7, characterized in that, In step 3, the base is fixed on the vacuum electron beam welding workbench; after determining the working distance, the door is closed, and the vacuum chamber is evacuated to 5x10-5 mbr; spot welding with a penetration depth of 1 mm, sealing welding with a penetration depth of 2 mm, formal welding with a penetration depth of 9 mm, and finishing welding with a penetration depth of 2.5 mm are performed in sequence; after depressurization, the vacuum chamber is opened, the weld is inspected, and the base is removed.

10. The welding method for an electrostatic chuck base according to claim 7, characterized in that, Before step 1, the base body and cover plate to be welded are chemically cleaned and packaged. The packaging is opened and installed before welding the base.

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