Glass solder with low thermal expansion coefficient for connecting silicon carbide vacuum chucks, preparation method and connecting method

Abstract

The invention relates to a low-thermal-expansion-coefficient glass solder for connecting silicon carbide vacuum chucks, a preparation method and a connecting method. The glass solder with the low thermal expansion coefficient comprises the following chemical components in percentage by weight: 1 to 5 percent of Al2O3, 26 to 31.3 percent of B2O3, 59.1 to 68 percent of SiO2, 2.1 to 5.5 percent of R2O, 0.2 to 2 percent of RO and 0.1 to 2 percent of RExOy, wherein the sum of the mass percent of all the components is 100 percent. The thermal expansion coefficient of the glass solder provided by the invention is matched with that of a connected silicon carbide chuck body, so that the connection quality of the silicon carbide vacuum chuck is effectively improved. The silicon carbide vacuum chuck connected by the glass solder has the advantages of high welding rate, low helium leakage rate, good water pressure resistance strength and long-term stable flatness. The connection process provided by the invention is stable and reliable, is simple and convenient to operate, and has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of ceramic material welding, specifically relating to a low thermal expansion coefficient glass solder for connecting silicon carbide vacuum chucks, its preparation method, and its connection method. Background Technology

[0002] Semiconductor vacuum chucks, as key clamping devices in chip manufacturing processes such as photolithography, etching, and polishing, directly determine the processing accuracy and production yield of semiconductor devices. These chucks are based on the principle of vacuum adsorption, utilizing the porous ceramic microstructure of silicon carbide to achieve non-destructive wafer fixation. They possess excellent high-temperature stability (>300°C), resistance to chemical corrosion (such as resistance to plasma etching gases), and modular design adaptability suitable for 4- to 12-inch wafer manufacturing. With the continuous miniaturization of semiconductor process nodes (such as sub-3nm technology), the vacuum chuck structure increasingly demands high integration, requiring the construction of a dense water / air channel network within a limited space to achieve wafer temperature control, self-cleaning, and multi-physics field manipulation. Silicon carbide (SiC) ceramics are highly suitable due to their excellent high-temperature strength, high thermal conductivity, and extremely low coefficient of thermal expansion (CTE ~ 4.0 × 10⁻⁶). -6 Due to its excellent corrosion resistance (as described by the character / K), SiC is widely used in the first wall materials of nuclear fusion reactors, aerospace hot-end components, semiconductor wafer chucks, and high-performance heat exchangers. However, the intrinsic properties of SiC make its bonding extremely difficult, facing three major physicochemical challenges.

[0003] Wettability Challenges: SiC is a typical covalent compound with low surface energy, and it readily forms a dense silicon oxide (SiO2) film or remains chemically inert at high temperatures. Most conventional oxide glasses exhibit large wetting angles on SiC surfaces, making them difficult to spread. To improve wettability, it is usually necessary to reduce the surface tension of the glass melt or introduce active elements. High boron oxide (B2O3) content is an effective means of reducing surface tension and improving flowability, but excessively high boron content often leads to a sharp decline in the chemical stability of the glass.

[0004] Thermal expansion matching: SiC has a very low CTE (~4.0 × 10⁻⁶). -6 / K). If the bonding material (e.g., ordinary soda-lime glass CTE ~ 9.0 × 10) -6 The CTE of K is significantly higher than that of SiC, and huge tensile stress will be generated at the interface during the cooling process, causing the joint to crack instantly.

[0005] Interface reactions and bubble defects: These are the most insidious but deadliest defects in SiC bonding. At high temperatures (>1000℃), oxygen or oxides in the glass melt readily undergo redox reactions with the SiC surface.

[0006] The carbon monoxide (CO) and silicon monoxide (SiO) gases produced by the reaction become trapped in the viscous glass weld, forming numerous microbubbles. These bubbles not only reduce joint strength by decreasing the effective connection area, but they also act as sources of stress concentration, leading to joint failure. Existing technologies often struggle to eliminate these bubbles without compromising the glass's properties. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention aims to provide a low thermal expansion coefficient glass solder, its preparation method, and a joining method for joining silicon carbide vacuum chucks. By controlling the composition of the glass solder, a thermal expansion coefficient that closely matches that of silicon carbide can be obtained. Furthermore, this joining technology can produce silicon carbide vacuum chucks with excellent strength at both room temperature and high temperature. These chucks exhibit high welding efficiency, low helium leakage rate, good water pressure resistance, and long-term stable flatness. This joining process is simple, has high engineering application potential, and shows great promise for future applications.

[0008] In a first aspect, the present invention provides a low thermal expansion coefficient glass solder for connecting silicon carbide vacuum chucks, the low thermal expansion coefficient glass solder having the following chemical composition: 1–5 wt.% Al₂O₃, 26–31.3 wt.% B₂O₃, 59.1–68 wt.% SiO₂, 2.1–5.5 wt.% R₂O, 0.2–2 wt.% RO, and 0.1–2 wt.% RE. x O y The sum of the mass percentages of each component is 100 wt.%.

[0009] Preferably, the chemical composition of the low thermal expansion coefficient glass solder includes: 1.3–4.5 wt.% Al2O3, 26.5–30.7 wt.% B2O3, and 61.4–67.2 wt.% SiO2.

[0010] Preferably, the R2O comprises 1–1.5 wt.% Li2O, 1–3 wt.% Na2O, and 0.1–1 wt.% K2O; more preferably, the R2O comprises 1–1.2 wt.% Li2O, 1.5–2 wt.% Na2O, and 0.3–0.5 wt.% K2O. The RO contains 0.1–1 wt.% CaO and 0.1–1 wt.% MgO; preferably, the R2O contains 0.1–0.5 wt.% CaO and 0.2–1 wt.% MgO. The RE x O y The content is 0.1–2 wt.% CeO2, preferably, the RE x O y It is 0.5–1 wt.% CeO2.

[0011] Preferably, the low thermal expansion coefficient glass solder is in powder form with a particle size of 1μm to 44μm.

[0012] Preferably, the glass transition temperature of the low thermal expansion coefficient glass solder is 460–510°C, and the softening point is 570–630°C.

[0013] Preferably, the low thermal expansion coefficient glass solder has a thermal expansion coefficient of (3.5 to 4.0) × 10⁻⁶ between 20 and 400°C. -6 / K.

[0014] Secondly, the present invention also provides a method for preparing the above-mentioned low thermal expansion coefficient glass solder, comprising: (1) Weigh and mix Al2O3 powder, H3BO3 powder, SiO2 powder, K2CO3 powder, Li2O powder, Na2CO3 powder, CaCO3 powder, MgO powder and CeO2 powder in proportion, and obtain a mixture by ball milling, drying, grinding and sieving; (2) Melt the mixture to obtain a molten sample; (3) The molten sample is placed in deionized water and rapidly cooled to obtain a block glass sample. After drying, crushing, ball milling and sieving, the low thermal expansion coefficient glass solder is obtained.

[0015] Preferably, in step (1), the purity of the K2CO3 powder, Li2O powder, Na2CO3 powder, CaCO3 powder, MgO powder and CeO2 powder is ≥99.0%; the purity of the Al2O3 powder, H3BO3 powder and SiO2 powder is ≥99.5%; and the average particle size of the Al2O3 powder, H3BO3 powder, SiO2 powder, K2CO3 powder, Li2O powder, Na2CO3 powder, CaCO3 powder, MgO powder and CeO2 powder is 5-10 μm. The ball mill is a wet ball mill, and the parameters of the wet ball mill include: the mixing medium is anhydrous ethanol, the amount of anhydrous ethanol added is 80-120% of the mixture, the grinding balls are zirconia ceramic balls, the ratio of raw material to grinding balls is (1-2):(2-3), the rotation speed is 200-300 rpm, and the time is 1-2 hours. The drying temperature is 50–80°C, and the drying time is 12–24 hours. The sieve mesh size is 80-100 mesh.

[0016] Preferably, in step (2), the melting temperature is 1500-1700℃ and the holding time is 1-3 hours; preferably, the melting parameters include: first heating to 800-1000℃ at a heating rate of 5-10℃ / min, then heating to 1500-1700℃ at a heating rate of 3-5℃ / min, and holding for 1-3 hours.

[0017] Preferably, in step (3), the drying temperature is 60-100°C and the time is 6-12 hours; The parameters of the ball mill include: dry grinding without mixing media, grinding balls are agate balls, the grinding jar is an agate grinding jar, the rotation speed is 250-300 rpm, and the grinding time is 18-24 hours.

[0018] The sieve mesh size is 325 to 1250 mesh.

[0019] Thirdly, the present invention provides a method for connecting a silicon carbide vacuum chuck using the aforementioned low thermal expansion coefficient glass solder, comprising: (1) A glass solder with a low coefficient of thermal expansion is mixed with an organic carrier to obtain a glass slurry; (2) The obtained glass paste is uniformly coated on the surface of the silicon carbide disk to be connected by screen printing. After debonding treatment, a glass solder layer is formed on the surface of the silicon carbide disk to be connected. (3) The silicon carbide disk with the glass solder layer is fixed to another silicon carbide disk in a sandwich structure. After welding, it is naturally cooled to room temperature in the furnace, thus completing the connection of the silicon carbide vacuum chuck.

[0020] Preferably, in step (1), the organic carrier includes an adhesive and a solvent; wherein the mass ratio of the adhesive to the solvent is (5-10):(90-95). The binder is at least one of methylcellulose, ethylcellulose, polyvinyl alcohol, and phenolic resin; The solvent is at least one selected from terpineol, triterpenol, ethyl acetate, and butyl acetate; The method for preparing the organic carrier includes: mixing the binder and solvent in a mass ratio and stirring at 20-100°C for 4-8 hours to obtain the organic carrier; The amount of the organic carrier is 60-70 wt. of the glass solder mass.

[0021] Preferably, in step (2), the parameters of the debonding treatment include: heating to 240-260°C at a heating rate of 4-5°C / min, then continuing to heat to 440-460°C at a heating rate of 1-3°C / min, and holding at that temperature for 20-30 minutes.

[0022] Preferably, in step (2), the thickness of the glass slurry layer is 100-200 μm.

[0023] Preferably, the silicon carbide disk is prepared by atmospheric pressure sintering, reaction sintering, recrystallization or chemical vapor deposition.

[0024] Preferably, in step (3), the temperature of the welding process is 900-1000℃ and the holding time is 30-60min; preferably, the parameters of the welding process include: heating to 440-460℃ at a heating rate of 4-5℃ / min, then continuing to heat to 900-1000℃ at a heating rate of 2℃ / min, holding for 30-60min, and finally cooling to 440-460℃ at a cooling rate of 2-4℃ / min; more preferably, the ambient atmosphere is at least one of air, vacuum, and argon.

[0025] Fourthly, the present invention provides a silicon carbide vacuum chuck obtained by the connection method described above, wherein the room temperature shear strength of the silicon carbide vacuum chuck is ≥55MPa; The silicon carbide vacuum chuck has a welding rate of ≥95% under vacuum conditions, and the helium leakage rate of the vacuum chuck after welding is <1×10⁻⁶. -13 Pa, water pressure resistance ≥6 MPa, PV 300nm flatness change <300nm within three months. Beneficial effects

[0026] (1) The Al2O3-B2O3-SiO2-R2O-RO-RE used in this invention x O y The glass solder exhibits excellent chemical compatibility with the silicon carbide disk, and its coefficient of thermal expansion in the range of 20–400℃ is (3.5–4.0) × 10⁻⁶. -6 / K, which is compatible with the thermal expansion coefficient of the connected silicon carbide disk, effectively improves the connection quality of the silicon carbide vacuum chuck. (2) The present invention adopts Al2O3-B2O3-SiO2-R2O-RO-RE x O y Glass solder can achieve the connection of silicon carbide vacuum chucks at 900-1000℃, reducing the process difficulty of connecting silicon carbide vacuum chucks. The silicon carbide vacuum chucks connected by this glass solder have a room temperature shear strength of over 55MPa, a welding rate of over 95% under vacuum conditions, and a helium leakage rate of less than 1×10⁻⁶ after welding. -13 Pa, water pressure resistance of over 6 MPa, and PV300nm flatness change of less than 300nm within three months; (3) The glass welding process used in this invention is stable and reliable, easy to operate, and has important application value. Attached Figure Description

[0027] Figure 1 This is a diagram of the original powder of the glass solder prepared in Example 1 of the present invention; Figure 2 Schematic diagram of the process of connecting silicon carbide vacuum chucks to glass solder; Figure 3 Schematic diagram showing the coefficient of thermal expansion measured for silicon carbide substrate (RB-SiC), glass solder of Example 1 and Comparative Examples 2-6; Figure 4 These are microscopic images of the internal morphology of the glass layers obtained by welding in Example 1 and Comparative Examples 2-3; Figure 5 This is a macroscopic morphology image of the silicon carbide substrate surface after screen printing and debonding process in Embodiment 1 of the present invention. Detailed Implementation

[0028] To further illustrate the invention's content, features, and practical effects, the invention will be described in detail below with reference to embodiments. It should be noted that the modification methods of the invention are not limited to these specific implementation methods. Equivalent substitutions and modifications made by those skilled in the art based on their reading of the invention's content, without departing from the spirit and essence of the invention, are also within the scope of protection claimed by this invention.

[0029] First, the present invention provides a low thermal expansion coefficient glass solder for connecting silicon carbide vacuum chucks. The chemical composition of the low thermal expansion coefficient glass solder includes: 1-5 wt.% Al2O3, 26-31.3 wt.% B2O3, 59.1-68 wt.% SiO2, 2.1-5.5 wt.% R2O, 0.2-2 wt.% RO, and 0.1-2 wt.% RE. x O yThe sum of the mass percentages of all components is 100 wt.%. If the SiO2 content is too high, it will further increase the melting and bonding temperatures, and while increasing the difficulty of glass powder preparation and application, it will significantly reduce the coefficient of thermal expansion of the glass solder, leading to thermal stress mismatch between it and the silicon carbide matrix. Furthermore, excessive SiO2 content will cause a sharp increase in the high-temperature viscosity of the glass, resulting in poor fluidity and wettability, and consequently, the precipitation of a large number of crystals during the bonding process. If the B2O3 content is too high, it will increase the proportion of [BO3] in the glass network, leading to a decrease in the stability of the glass network. Conversely, excessive B2O3 content will lead to an increase in CTE, resulting in a more severe thermal stress mismatch than a decrease in CTE. Additionally, excessive boron oxide may exacerbate boron anomalies, increasing the tendency for phase separation of the liquid glass during bonding, and may lead to high-temperature volatilization, causing component loss during bonding, ultimately causing the composition and performance of the bonding layer to deviate from the design expectations. The low thermal expansion coefficient glass solder has a thermal expansion coefficient of (3.5~4.0)×10⁻¹⁰ between 20 and 400°C. -6 / K is very well matched with the thermal expansion coefficient of silicon carbide vacuum chucks, and has good chemical compatibility with silicon carbide vacuum chucks.

[0030] Compared with traditional glass solders, the glass-forming matrix of the present invention belongs to a typical high borosilicate system, in which the total amount of SiO2 and B2O3 is close to 95%.

[0031] The unique characteristic of high B2O3 content: The B2O3 content of ordinary borosilicate glass is typically around 12-13%. The B2O3 content in this invention is exceptionally high, approaching or even exceeding that of typical commercial sealing glasses (such as Schott 8250, with a boron content of approximately 24%). In the presence of alkali metal oxides, boron atoms transform from two-dimensional layered trigonal structures to three-dimensional framework tetrahedrons. This change in coordination number tightens the glass network, significantly reducing the coefficient of thermal expansion (CTE). This invention utilizes a high-boron-content glass solder formulation to achieve extremely low CTE to match SiC (~4.0 × 10⁻⁶). -6 / K), while significantly reducing the softening point, enabling the bonding process to be completed at a lower temperature (expected 900-1000°C), thereby protecting the SiC matrix.

[0032] Al₂O₃ plays a crucial role as a "network stabilizer" in glass solder formulations. Studies have shown that when Al₂O₃ is added to borosilicate glass, aluminum ions, due to the need for charge compensation, preferentially combine with alkali metal ions to enter the network and form [AlO₄] tetrahedra. When Al… 3+ Located within [AlO4], it forms a unified network with silicon-oxygen tetrahedra, with a small amount of Al2O3 introduced. 3+This allows non-bridging oxygen to be captured and form [AlO4] tetrahedra that enter the silicon-oxygen network, reconnecting the broken networks in the glass and making the glass structure more compact. Therefore, due to the presence of a small amount of Al2O3, a series of glass properties are improved.

[0033] The glass solder formulation of this invention simultaneously incorporates three alkali metals: lithium, sodium, and potassium, with a total content of approximately 2.1–5.5 wt.%. When two or more alkali metal ions are present in the glass, a mixed alkali effect may occur, which mutually hinders ion mobility. This typically leads to a significant increase in the glass resistivity (advantageous for electronic packaging). More importantly, the mixed alkali effect can significantly suppress crystallization tendency. Preventing glass solder crystallization is crucial for ensuring controllable residual stress in the vacuum chuck during the slow cooling process of silicon carbide vacuum chuck connections. Furthermore, K₂O and Li₂O, as fluxing oxides, can provide free O₂. 2- Ions disrupt the Si-O-Si and BOB bonding networks, thereby lowering the melting point and viscosity, and reducing the difficulty of preparation. The most crucial role of Na₂O is that, as a strong network modifier, its introduction significantly disrupts the special boron-oxygen ring structure composed of [BO₃] units in the original glass, driving its transformation to [BO₄] and generating a large amount of non-bridging oxygen. This directly leads to the depolymerization of the glass network, increased hydrophilicity, and a general increase in the coefficient of thermal expansion. However, it is precisely this "destructive" behavior that allows the coefficient of thermal expansion of the glass solder to be adjusted to perfectly match that of the silicon carbide vacuum chuck, laying the primary foundation for obtaining high bonding strength. If the glass solder does not contain Na₂O, the lack of Na will first cause problems. + Ions break the Si-O-Si bonds and BOB bonds in the glass mesh, significantly reducing the glass's coefficient of thermal expansion; secondly, they lead to the formation of Ce bonds within the dense glass mesh. 4+ Unable to be stably integrated into the glass network, it undergoes local segregation and induces the precipitation of cerium-rich crystalline phases. The precipitation of these crystals disrupts the glass mesh structure and further reduces the bonding performance. This phenomenon becomes more pronounced with increasing temperature.

[0034] The glass solder formulation of this invention also incorporates two alkaline earth metals, calcium and magnesium, with a total content of approximately 0.2–2 wt.%. Trace amounts of calcium and magnesium oxides are primarily used to fine-tune the glass's "length and shortness" (slope of the viscosity-temperature curve) and chemical stability. MgO is particularly helpful in improving the glass's elastic modulus, thereby alleviating thermal mismatch stress in the vacuum chuck to some extent. Furthermore, MgO also plays a structural "anchoring" role within the glass's internal structure. Due to Mg... 2+The high ionic field strength of ions exerts a strong polarization effect on surrounding oxygen atoms, effectively "clamping" the crystal lattice structure and limiting thermal vibrations. Removing MgO makes the glass framework more susceptible to thermal disturbances, leading to a sudden increase in the coefficient of thermal expansion and reduced welding strength. If the glass solder does not contain CaO, the mesh will lack charge compensator, hindering the promotion of Al... 3+ The MgO enters the grid in the form of [AlO4]. Simultaneously, due to the lack of CaO, the precipitation temperature of the MgO·Al2O3·SiO2 crystal form decreases, and strip-shaped crystals precipitate inside the glass at approximately 900℃, reducing bonding performance. If the glass solder does not contain MgO, it will reduce the ionic bond strength between the glass grids, thereby reducing the hardness, flexural strength, and abrasion resistance of the glass body, and may also reduce the glass's hydrolysis resistance.

[0035] Furthermore, cerium, a rare earth metal, is introduced into the glass solder formulation of this invention, with a total content of approximately 0.1–2 wt.%. As mentioned earlier, silicon carbide vacuum chuck connections face a severe interfacial gas generation problem (CO / SiO). CeO2 is a variable-valence oxide that exists at high temperatures. Balance. When interfacial reactions lead to a decrease in local oxygen partial pressure (reducing atmosphere), CeO2 can release oxygen and inhibit the active decomposition of SiC. More importantly, CeO2 acts as a clarifying agent, promoting the coalescence and expulsion of small bubbles or absorbing trace gases, thereby eliminating interfacial microbubbles. Additionally, rare earth oxides (such as CeO2, Y2O3) have been shown to reduce the contact angle of silicate glass on covalently bonded ceramics (such as Si3N4, SiC), improving wetting and spreading properties. Since interfacial reactions generate gases that form pores within the weld layer, it is usually necessary to control the bonding temperature to reduce pore formation. If the glass solder does not contain CeO2, it will be difficult for the glass solder to wet the ceramic surface at the set bonding temperature, resulting in unbonded areas.

[0036] The following is an exemplary description of the preparation method of the low thermal expansion coefficient glass solder provided by the present invention.

[0037] Preparation of the mixture: Al2O3 powder, H3BO3 powder, SiO2 powder, K2CO3 powder, Li2O powder, Na2CO3 powder, CaCO3 powder, MgO powder and CeO2 powder are weighed and mixed in proportion, and then ball-milled, dried, ground and sieved to obtain the mixture.

[0038] In an optional embodiment, the purity of the K2CO3 powder, Li2O powder, Na2CO3 powder, CaCO3 powder, MgO powder, and CeO2 powder is ≥99.0%; the purity of the Al2O3 powder, H3BO3 powder, and SiO2 powder is ≥99.5%; and the average particle size of the Al2O3 powder, H3BO3 powder, SiO2 powder, K2CO3 powder, Li2O powder, Na2CO3 powder, CaCO3 powder, MgO powder, and CeO2 powder is 5–10 μm.

[0039] In an optional embodiment, the ball milling is a wet ball milling process. The parameters of the wet ball milling process include: the mixing medium is anhydrous ethanol, the amount of anhydrous ethanol added is 80-120% of the mixture, the grinding balls are zirconia ceramic balls, the ratio of raw material to grinding balls is (1-2):(2-3), the rotation speed is 200-300 rpm, and the time is 1-2 hours. The drying temperature is 50-80℃, and the drying time is 12-24 hours. The sieve mesh size is 80-100 mesh.

[0040] Preparation of glass samples: The mixture is placed in a crucible and melted in a muffle furnace. Then, the molten sample is poured directly into deionized water at a holding temperature and rapidly cooled to obtain a block glass sample.

[0041] In an optional embodiment, the melting parameters include: a melting temperature of 1500–1700°C and a melting time of 1–3 hours; preferably, the melting parameters include: first heating to 800–1000°C at a heating rate of 5–10°C / min, then heating to 1500–1700°C at a heating rate of 3–5°C / min, and holding at that temperature for 1–3 hours.

[0042] Preparation of glass solder: The block glass sample was crushed into powder using a multi-functional pulverizer, then hand-ground in a mortar, dried, and sieved to obtain Al2O3-B2O3-SiO2-R2O-RO-RE. x O y Glass solder.

[0043] In an optional embodiment, the drying temperature is 60–100°C, and the time is 6–12 hours. The ball milling parameters include: dry grinding without mixing media, agate balls, an agate ball mill jar, a rotation speed of 250–300 rpm, and a milling time of 18–24 hours. The sieve mesh size is 325–1250 mesh.

[0044] The following exemplarily illustrates a method for connecting silicon carbide vacuum chucks using the aforementioned low thermal expansion coefficient glass solder (e.g. Figure 2 (As shown).

[0045] A glass slurry is obtained by mixing a glass solder with a low coefficient of thermal expansion and an organic carrier.

[0046] In an optional embodiment, the organic carrier comprises a binder and a solvent; wherein the mass ratio of the binder to the solvent is (5-10):(90-95). The binder is at least one selected from methylcellulose, ethylcellulose, polyvinyl alcohol, and phenolic resin. The solvent is at least one selected from terpineol, triterpene alcohol, ethyl acetate, and butyl acetate. The method for preparing the organic carrier comprises: mixing the binder and solvent in a mass ratio, and stirring at 20-100°C for 4-8 hours to obtain the organic carrier. The amount of the organic carrier is 60-70 wt.% of the mass of the glass solder.

[0047] The obtained glass paste is uniformly coated onto the bonding surface of the silicon carbide disk using screen printing. After debonding, a glass solder layer is formed on the bonding surface of the silicon carbide disk.

[0048] In an optional embodiment, the parameters of the debonding treatment include: heating to 240-260°C at a heating rate of 4-5°C / min, then continuing to heat to 440-460°C at a heating rate of 1-3°C / min, and holding at that temperature for 20-30 minutes.

[0049] In an optional embodiment, the thickness of the glass slurry layer can be 100–200 μm.

[0050] The silicon carbide disk with a glass solder layer is fixed to another silicon carbide disk in a sandwich structure using a clamp (such as an alumina clamp) (i.e., the glass solder layer of the silicon carbide disk faces the connection surface of the other silicon carbide disk), and a certain counterweight pressure is applied. The disk is then placed in a muffle furnace for welding. After the heat preservation is completed, the silicon carbide vacuum chuck is naturally cooled with the furnace to complete the connection.

[0051] In an optional embodiment, the temperature is increased to 440-460°C at a heating rate of 4-5°C / min, then increased to 900-1000°C at a heating rate of 2°C / min, held for 30-60 minutes, and finally decreased to 440-460°C at a cooling rate of 2-4°C / min. Preferably, the ambient atmosphere is at least one of air, vacuum, and argon. If the welding temperature is too low, the high viscosity of the glass at low temperatures will prevent complete filling of the weld layer, and it will also be insufficient to catalyze the interfacial reaction at the glass-silicon carbide interface, leading to connection failure. If the welding temperature is too high, crystallization will occur within the glass phase, damaging the glass mesh. Simultaneously, the interfacial reaction at the glass-silicon carbide interface will become uncontrolled, generating a large amount of gas that remains within the weld layer, forming pores that penetrate the weld layer and severely reducing connection performance. If the welding time is too short, the interfacial bonding will be poor; if the welding time is too long, glass solder will accumulate during the connection process, leading to pores.

[0052] In this invention, the purpose of employing a pre-debonding followed by welding approach is to: during the debonding process, allow the organic carrier to completely volatilize, reducing the possibility of impurities and residual pores, leaving only the glass powder itself, while simultaneously forming a uniform, continuous, and dense glass powder layer that is less prone to detachment during subsequent welding and assembly. The welding process completes the uniform transformation of the glass and achieves connection. Compared to one-step welding, pre-debonding followed by welding effectively reduces the residue of organic carriers, ensures the purity of the weld, improves connection performance, and is more conducive to industrial production in various fields.

[0053] In this invention, the prepared glass solder has a thermal expansion coefficient that is compatible with that of the silicon carbide vacuum chuck, and has good chemical compatibility, thereby realizing the connection of the silicon carbide vacuum chuck, effectively improving the connection strength and connection quality of the silicon carbide vacuum chuck, and the process is stable and reliable.

[0054] In this invention, the room temperature shear strength of a silicon carbide vacuum chuck is tested using the following assembly method: a silicon carbide substrate (5×5×30 mm) with a glass solder layer is formed. 3 ) and another silicon carbide substrate (5×15×30 mm) 3 The silicon carbide substrate with a glass solder layer is located in the center of the uncoated silicon carbide substrate, forming a convex sandwich structure. The room temperature shear strength of the silicon carbide vacuum chuck connected using the aforementioned low thermal expansion coefficient glass solder exceeds 55 MPa.

[0055] In this invention, the welding rate of the silicon carbide vacuum chuck after connection, tested using an ultrasonic scanning microscope, is over 95% under vacuum conditions; the helium leakage rate of the vacuum chuck after welding, tested using a helium mass spectrometer, is less than 1×10⁻⁶. -13 Pa; the water pressure resistance of the silicon carbide vacuum chuck was tested using a water pressure burst test and found to be above 6 MPa; the PV300nm flatness of the silicon carbide vacuum chuck changed by less than 300nm within three months when tested using a laser flatness measuring instrument.

[0056] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below. Example 1

[0057] (I) Preparation of glass powder (1) Weigh and mix Al2O3 powder, H3BO3 powder, SiO2 powder, K2CO3 powder, Li2O powder, Na2CO3 powder, CaCO3 powder, MgO powder, and CeO2 powder according to the mass ratio shown in the formula. The formula and proportions of the glass solder are shown in Table 1. The raw materials are mixed by wet ball milling. The solvent used for mixing is anhydrous ethanol with a purity of 99.5%, and the amount added is 100% of the mixed powder. The ball milling media is zirconia balls, wherein the ratio of raw materials to grinding balls is 1:2. The above raw materials are added sequentially into the ball mill jar and ball milled at 300 r / min for 1 h to obtain the mixed powder.

[0058] Table 1 lists the raw materials and proportions used in glass solder: .

[0059] (2) The mixed powder was dried in an oven at 60°C for 12 hours, ground, and then passed through an 80-mesh sieve. A certain amount of glass raw material was placed in an alumina crucible and melted in a high-temperature heating furnace. The temperature was raised to 800°C at a rate of 10°C / min, and then raised to 1600°C at a rate of 5°C / min. The temperature was held for 2 hours. The molten sample was then poured directly into deionized water and rapidly cooled to obtain a block glass sample.

[0060] (3) After drying at 60℃ for 12 hours, the block glass sample was crushed using a multi-functional pulverizer and then ball-milled in an agate ball mill jar. After passing through a 325-mesh sieve, Al2O3-B2O3-SiO2-R2O-RO-RE was obtained. x O y Glass powder.

[0061] (ii) Connection of silicon carbide vacuum chuck (1) Weigh ethyl cellulose and terpineol in a mass ratio of 5:95, pour them into a sealed beaker and stir in a constant temperature magnetic stirrer at 90°C for 4 hours until the ethyl cellulose is completely dissolved. Then cool to room temperature to obtain an organic carrier. Take a certain amount of glass powder obtained in step (1) and mix it evenly with the organic carrier to obtain a glass slurry. The amount of organic carrier is 70 wt. of the glass powder.

[0062] (2) The surface of the silicon carbide disk to be welded is polished step by step using 500, 800, 1200 and 1600 grit wet sandpaper, and then ultrasonically cleaned with anhydrous ethanol. The silicon carbide disk is prepared by reaction sintering.

[0063] (3) The glass paste is uniformly coated on the surface of the silicon carbide disk to be connected after polishing by screen printing. After debonding treatment, a glass solder layer with a thickness of 200μm is formed on the surface of the silicon carbide disk to be connected. The debonding treatment parameters include: heating to 250℃ in a muffle furnace at a heating rate of 5℃ / min, and then continuing to heat to 450℃ at a heating rate of 1.6℃ / min, and holding for 30min.

[0064] (4) Using an alumina clamp, the silicon carbide disk with the glass solder layer formed is fixed to another silicon carbide disk in a sandwich structure and placed in a muffle furnace for welding. The welding parameters include: heating to 450°C at a heating rate of 5°C / min, then continuing to heat to 900°C at a heating rate of 2°C / min, holding at that temperature for 30 min, cooling down to 450°C at a cooling rate of 3°C / min, and finally cooling naturally with the furnace to complete the connection of the silicon carbide vacuum chuck.

[0065] The glass solder obtained in Example 1 has a glass transition temperature of 503℃, a softening point of 592℃, and a coefficient of thermal expansion of 3.9 × 10⁻⁶ between 20℃ and 400℃. -6 The coefficient of thermal expansion (C / K) is almost perfectly matched to that of the silicon carbide vacuum chuck. Furthermore, the interface bonding effect after joining with glass solder is excellent, and the resulting silicon carbide vacuum chuck achieves a room temperature shear strength of 83 MPa. The welding rate under vacuum conditions is 97.6%, and the helium leakage rate of the welded vacuum chuck is <1×10⁻⁶. -13 Pa, water pressure resistance ≥7 MPa, PV300nm flatness changes by 186nm within three months.

[0066] Figure 1 This is a diagram of the original powder of the glass solder prepared in Example 1 of the present invention. As can be seen from the diagram, the glass solder prepared in Example 1 of the present invention is a white powder. This is due to its strong light scattering effect, indicating that its particle size is very small, meeting the requirements for subsequent applications.

[0067] Figure 5 This is a macroscopic morphology image of the silicon carbide substrate surface after screen printing and debinding process in Embodiment 1 of the present invention. As shown in the figure, after debinding, a uniform, continuous and dense glass powder layer is formed on the surface of the silicon carbide substrate. Example 2

[0068] The preparation method of low thermal expansion coefficient glass solder and the connection process of silicon carbide vacuum chuck in this embodiment 2 are the same as in embodiment 1, except that: (i) Preparation of glass powder: In step (1), the glass solder component ratio is different, as shown in Table 2.

[0069] Table 2 lists the raw materials and proportions used in glass solder: .

[0070] The glass solder obtained in Example 2 has a glass transition temperature of 474℃, a softening point of 589℃, and a coefficient of thermal expansion of 3.5×10⁻⁶ between 20℃ and 400℃. -6 The coefficient of thermal expansion (COP) is close to that of silicon carbide vacuum chucks. Furthermore, the interface bonding effect after joining with glass solder is excellent, and the room temperature shear strength of the resulting silicon carbide vacuum chuck reaches 60 MPa. The welding rate in a vacuum environment is 96.8%, and the helium leakage rate of the welded vacuum chuck is <1×10⁻⁶. -13 Pa, water pressure resistance ≥7 MPa, PV300nm flatness changes by 249nm within three months. Example 3

[0071] The preparation method of low thermal expansion coefficient glass solder and the connection process of silicon carbide vacuum chuck in this embodiment 3 are the same as in embodiment 1, except that: (i) Preparation of glass powder: In step (1), the glass solder component ratio is different, as shown in Table 3.

[0072] Table 3 lists the raw materials and proportions used in glass solder: .

[0073] The glass solder obtained in Example 3 has a glass transition temperature of 482℃, a softening point of 582℃, and a coefficient of thermal expansion of 3.7×10⁻⁶ between 20℃ and 400℃. -6 The coefficient of thermal expansion (COP) is close to that of silicon carbide vacuum chucks. Furthermore, the interface bonding effect after joining with glass solder is excellent, and the room temperature shear strength of the resulting silicon carbide vacuum chuck reaches 55 MPa. The welding rate in a vacuum environment is 95.3%, and the helium leakage rate of the welded vacuum chuck is <1×10⁻⁶. -13 Pa, water pressure resistance ≥7 MPa, PV300nm flatness changes by 293nm within three months. Example 4

[0074] The preparation method of low thermal expansion coefficient glass solder and the connection process of silicon carbide vacuum chuck in this embodiment 4 are the same as in embodiment 1, except that: (i) Preparation of glass powder: In step (2), the melting process is: heating from room temperature to 1700℃ at a heating rate of 10℃ / min and holding for 2h.

[0075] The glass solder obtained in Example 4 has a glass transition temperature of 503℃, a softening point of 592℃, and a coefficient of thermal expansion of 3.9 × 10⁻⁶ between 20℃ and 400℃. -6The coefficient of thermal expansion (COP) is close to that of silicon carbide vacuum chucks. Furthermore, the interface bonding effect after joining with glass solder is excellent, and the resulting silicon carbide vacuum chuck exhibits a room temperature shear strength of 80 MPa. The welding rate under vacuum conditions is 97.7%, and the helium leakage rate of the welded vacuum chuck is <1×10⁻⁶. -13 Pa, water pressure resistance ≥7 MPa, PV300nm flatness changes by 196 nm within three months. Example 5

[0076] The preparation method of the low thermal expansion coefficient glass solder and the connection process of the silicon carbide vacuum chuck in this embodiment 5 are the same as those in embodiment 1, except that: (ii) connection of silicon carbide ceramic: in step (4), the welding process is as follows: heat up to 450°C at a heating rate of 5°C / min, then continue to heat up to 950°C at a heating rate of 2°C / min, hold for 30 min, and then cool down to 450°C at a cooling rate of 3°C / min.

[0077] In Example 5, the interface bonding effect after joining with glass solder was excellent, and the room temperature shear strength of the resulting silicon carbide vacuum chuck reached 107 MPa. The welding rate under vacuum was 98.6%, and the helium leakage rate of the vacuum chuck after welding was <1×10⁻⁶. - 13 Pa, water pressure resistance ≥7 MPa, PV300nm flatness changes by 216nm within three months. Example 6

[0078] The preparation method of the low thermal expansion coefficient glass solder and the connection process of the silicon carbide vacuum chuck in this embodiment 6 are the same as those in embodiment 1, except that: (ii) connection of silicon carbide ceramic: in step (4), the welding process is as follows: heat up to 450°C at a heating rate of 5°C / min, then continue to heat up to 1000°C at a heating rate of 2°C / min, hold for 60 min, and then cool down to 450°C at a cooling rate of 3°C / min.

[0079] In Example 6, the interface bonding effect after joining with glass solder was excellent, and the room temperature shear strength of the resulting silicon carbide vacuum chuck reached 57 MPa. The welding rate under vacuum was 95.1%, and the helium leakage rate of the vacuum chuck after welding was <1×10⁻⁶. - 13 Pa, water pressure resistance ≥7 MPa, PV300nm flatness changes by 266nm within three months. Example 7

[0080] The preparation method of the low thermal expansion coefficient glass solder and the connection process of the silicon carbide vacuum chuck in this embodiment 7 are the same as those in embodiment 1, except that: (ii) connection of silicon carbide ceramic: in step (2), the silicon carbide disk is prepared by atmospheric pressure sintering.

[0081] In Example 7, the interface bonding effect after joining with glass solder was excellent, and the room temperature shear strength of the resulting silicon carbide vacuum chuck reached 78 MPa. The welding rate under vacuum was 95.6%, and the helium leakage rate of the vacuum chuck after welding was <1×10⁻⁶. - 13 Pa, water pressure resistance ≥7 MPa, PV300nm flatness changes by 235nm within three months. Comparative Example 1

[0082] The preparation method of the low thermal expansion coefficient glass solder and the connection process of the silicon carbide vacuum chuck in Comparative Example 1 are the same as in Example 1, except that: (i) Preparation of glass powder: In step (1), the glass solder component ratio is different, as shown in Table 4. Comparative Example 2

[0083] The preparation method of the low thermal expansion coefficient glass solder and the connection process of the silicon carbide vacuum chuck in Comparative Example 2 are the same as those in Example 1, except that: (i) Preparation of glass powder: In step (1), the glass solder component ratio is different, as shown in Table 4. Comparative Example 3

[0084] The preparation method of the low thermal expansion coefficient glass solder and the connection process of the silicon carbide vacuum chuck in this comparative example 3 are the same as those in example 1, except that: (i) Preparation of glass powder: In step (1), the glass solder component ratio is different, as shown in Table 4. Comparative Example 4

[0085] The preparation method of the low thermal expansion coefficient glass solder and the connection process of the silicon carbide vacuum chuck in Comparative Example 4 are the same as in Example 1, except that: (i) Preparation of glass powder: In step (1), the glass solder component ratio is different, as shown in Table 4. Comparative Example 5

[0086] The preparation method of the low thermal expansion coefficient glass solder and the connection process of the silicon carbide vacuum chuck in Comparative Example 5 are the same as in Example 1, except that: (i) Preparation of glass powder: In step (1), the glass solder component ratio is different, as shown in Table 4.

[0087] In Comparative Example 5, although the room temperature shear strength of the silicon carbide vacuum chuck obtained by joining with glass solder can reach 73 MPa, the welding rate of the vacuum chuck under vacuum environment is only 86.6%, and the helium leakage rate of the vacuum chuck after welding is approximately 1 × 10⁻⁶. -8 Pa, neither of them meets the design requirements. Comparative Example 6

[0088] The preparation method of the low thermal expansion coefficient glass solder and the connection process of the silicon carbide vacuum chuck in Comparative Example 6 are the same as in Example 1, except that: (i) Preparation of glass powder: In step (1), the glass solder component ratio is different, as shown in Table 4. Comparative Example 7

[0089] The preparation method of the low thermal expansion coefficient glass solder and the connection process of the silicon carbide vacuum chuck in Comparative Example 7 are the same as in Example 1, except that: (i) Preparation of glass powder: In step (1), the glass solder component ratio is different, as shown in Table 4.

[0090] In Comparative Example 7, the interface bonding effect after joining with glass solder was excellent, and the room temperature shear strength of the resulting silicon carbide vacuum chuck reached 87 MPa. The welding rate under vacuum was 98.1%, and the helium leakage rate of the vacuum chuck after welding was <1×10⁻⁶. -13 P. However, its water pressure resistance is <5MPa, which does not meet the design requirements. Comparative Example 8

[0091] The preparation method of the low thermal expansion coefficient glass solder and the connection process of the silicon carbide vacuum chuck in Comparative Example 8 are the same as in Example 1, except that: (i) Preparation of glass powder: In step (1), the glass solder component ratio is different, as shown in Table 4. Comparative Example 9

[0092] The preparation method of the low thermal expansion coefficient glass solder and the connection process of the silicon carbide vacuum chuck in Comparative Example 9 are the same as in Example 1, except that: (i) Preparation of glass powder: In step (1), the glass solder component ratio is different, as shown in Table 4. Comparative Example 10

[0093] The preparation method of the low thermal expansion coefficient glass solder and the connection process of the silicon carbide vacuum chuck in Comparative Example 10 are the same as those in Example 1, except that: (ii) Connection of silicon carbide ceramic: In step (4), the welding process is: the welding temperature is 800℃ and the welding time is 30min. Comparative Example 11

[0094] The preparation method of the low thermal expansion coefficient glass solder and the connection process of the silicon carbide vacuum chuck in Comparative Example 11 are the same as in Example 1, except that: (ii) Connection of silicon carbide ceramic: In step (4), the welding process is: the welding temperature is 1050℃ and the welding time is 30min. Comparative Example 12

[0095] The preparation method of the low thermal expansion coefficient glass solder and the connection process of the silicon carbide vacuum chuck in Comparative Example 12 are the same as those in Example 1, except that: (ii) Connection of silicon carbide ceramic: In step (4), the welding process is: the welding temperature is 900℃ and the welding time is 10min. Comparative Example 13

[0096] The preparation method of the low thermal expansion coefficient glass solder and the connection process of the silicon carbide vacuum chuck in Comparative Example 13 are the same as those in Example 1, except that: (ii) Connection of silicon carbide ceramic: In step (4), the welding process is: the welding temperature is 1000℃ and the welding time is 10min.

[0097] Table 4 lists the composition of the glass solder in Examples 1-3 and Comparative Examples 1-9: .

[0098] Figure 3 The diagram shows the measured coefficients of thermal expansion of the glass solders in Examples 1 and Comparative Examples 2-6. Table 5 lists the preparation parameters and properties of the glass solders in Examples 1-7 and Comparative Examples 1-13, as well as the welding parameters and performance parameters of the silicon carbide vacuum chuck: .

[0099] Combined with Table 4-5 and Figure 4 It can be seen that each additional R2O, RO and RE x O y The effects on the glass's intrinsic properties and bonding properties are significant. (1) For CaO, if the content is too low (Comparative Example 3), it lacks charge compensation, such as Figure 4 As shown, crystals will still precipitate inside the glass at the lowest bonding temperature, thus affecting the bonding strength; if the content is too high, its glass transition temperature will increase significantly, and it will also begin to precipitate inside the glass, similarly affecting the bonding strength. (2) For Na2O, if there is no Na2O (Comparative Example 2), the coefficient of thermal expansion of the glass will be significantly reduced, causing thermal stress mismatch between the glass and silicon carbide during the bonding process, and at the same time, Figure 4 As shown, in a dense glass mesh, Ce 4+ Unable to stably integrate into the glass network, it undergoes localized segregation and induces the precipitation of cerium-rich crystalline phases; if the content is too high (Comparative Example 7), the coefficient of thermal expansion will also increase accordingly, generating a mismatch of thermal stress from another direction. Furthermore, due to Na… +The hydrolytic properties of the glass mean that an excessively high content will result in the vacuum chuck after connection not having sufficient water pressure resistance and failing to meet the application specifications. (3) As a rare earth oxide, CeO2, if it is not present (Comparative Example 5), reduces the wettability between the glass and silicon carbide, resulting in the welding rate and helium leakage rate of the vacuum chuck obtained by welding not meeting the standards; if the content is too high (Comparative Example 9), it significantly increases the glass transition temperature and softening point temperature of the glass. Although the strength is still within the required range, it cannot be directly applied. In summary, the additional oxides not only affect the glass's own properties and connection performance, but the two oxides also interact with each other, further improving the glass performance. Therefore, all these oxides must be present at the same time and their content must be controlled. None of them can be omitted. Furthermore, if the welding temperature is too low, the high viscosity of the glass at low temperatures will prevent complete filling of the weld layer, and it will also be insufficient to catalyze the interfacial reaction at the glass-silicon carbide interface, leading to weld failure. If the welding temperature is too high, crystallization will occur within the glass phase, destroying the glass mesh. At the same time, the interfacial reaction at the glass-silicon carbide interface will become uncontrolled, generating a large amount of gas that remains within the weld layer, forming pores that penetrate the weld layer and severely reducing the weld performance. If the welding time is too short, the interfacial bonding will be poor, making it difficult to achieve the required weld ratio. If the welding time is too long, glass solder will accumulate during the connection process, leading to pores, which will also significantly affect the weld ratio.

Claims

1. A low thermal expansion coefficient glass solder for connecting silicon carbide vacuum chucks, characterized in that, The chemical composition of the low thermal expansion coefficient glass solder includes: 1–5 wt.% Al₂O₃, 26–31.3 wt.% B₂O₃, 59.1–68 wt.% SiO₂, 2.1–5.5 wt.% R₂O, 0.2–2 wt.% RO, and 0.1–2 wt.% RE. x O y The sum of the mass percentages of each component is 100 wt.%.

2. The low thermal expansion coefficient glass solder according to claim 1, characterized in that, The R2O contains 1–1.5 wt.% Li2O, 1–3 wt.% Na2O, and 0.1–1 wt.% K2O; The RO contains 0.1–1 wt.% CaO and 0.1–1 wt.% MgO; The RE x O y It is 0.1–2 wt.% CeO2.

3. The low thermal expansion coefficient glass solder according to claim 1 or 2, characterized in that, The low thermal expansion coefficient glass solder is in powder form with a particle size of 1μm to 44μm. The glass transition temperature of the low thermal expansion coefficient glass solder is 460–510°C, and the softening point is 570–630°C. The low thermal expansion coefficient glass solder has a thermal expansion coefficient of (3.5~4.0)×10⁻⁶ between 20 and 400°C. -6 / K.

4. A method for preparing a low thermal expansion coefficient glass solder according to any one of claims 1-3, characterized in that, include: (1) Weigh and mix Al2O3 powder, H3BO3 powder, SiO2 powder, K2CO3 powder, Li2O powder, Na2CO3 powder, CaCO3 powder, MgO powder and CeO2 powder in proportion, and obtain a mixture by ball milling, drying, grinding and sieving; (2) Melt the mixture to obtain a molten sample; (3) The molten sample is placed in deionized water and rapidly cooled to obtain a block glass sample. After drying, crushing, ball milling and sieving, the low thermal expansion coefficient glass solder is obtained.

5. The preparation method according to claim 4, characterized in that, The melting temperature is 1500-1700℃, and the holding time is 1-3 hours; preferably, the melting parameters include: first heating to 800-1000℃ at a heating rate of 5-10℃ / min, then heating to 1500-1700℃ at a heating rate of 3-5℃ / min, and holding for 1-3 hours.

6. A method for joining a silicon carbide vacuum chuck with a glass solder of low thermal expansion coefficient according to any one of claims 1-3, characterized in that, include: (1) A glass solder with a low coefficient of thermal expansion is mixed with an organic carrier to obtain a glass slurry; (2) The obtained glass paste is uniformly coated on the surface of the silicon carbide disk to be connected by screen printing. After debonding treatment, a glass solder layer is formed on the surface of the silicon carbide disk to be connected. (3) The silicon carbide disk with the glass solder layer is fixed to another silicon carbide disk in a sandwich structure. After welding, it is naturally cooled to room temperature in the furnace, thus completing the connection of the silicon carbide vacuum chuck.

7. The method according to claim 6, characterized in that, In step (1), the organic carrier includes a binder and a solvent; wherein the mass ratio of the binder to the solvent is (5-10):(90-95). The binder is at least one of methylcellulose, ethylcellulose, polyvinyl alcohol, and phenolic resin; The solvent is at least one selected from terpineol, triterpenol, ethyl acetate, and butyl acetate; The method for preparing the organic carrier includes: mixing the binder and solvent in a mass ratio and stirring at 20-100°C for 4-8 hours to obtain the organic carrier; The amount of the organic carrier is 60-70 wt. of the glass solder mass.

8. The method according to claim 6 or 7, characterized in that, In step (2), the parameters of the debonding treatment include: heating to 240-260°C at a heating rate of 4-5°C / min, then continuing to heat to 440-460°C at a heating rate of 1-3°C / min, and holding at the temperature for 20-30 minutes; The thickness of the glass slurry layer is 100–200 μm.

9. The method according to any one of claims 6-8, characterized in that, In step (3), the temperature of the welding process is 900-1000℃ and the holding time is 30-60min; preferably, the parameters of the welding process include: heating to 440-460℃ at a heating rate of 4-5℃ / min, then continuing to heat to 900-1000℃ at a heating rate of 2℃ / min, holding for 30-60min, and finally cooling to 440-460℃ at a cooling rate of 2-4℃ / min; more preferably, the ambient atmosphere is at least one of air, vacuum, and argon.

10. A silicon carbide vacuum chuck obtained by the method according to any one of claims 6-9, characterized in that, The room temperature shear strength of the silicon carbide vacuum chuck is ≥55MPa; The silicon carbide vacuum chuck has a welding rate of ≥95% under vacuum conditions, and the helium leakage rate of the vacuum chuck after welding is <1×10⁻⁶. - 13 Pa, water pressure resistance ≥6 MPa, PV 300nm flatness change <300nm within three months.

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