Graphite rod ceramic coating for epitaxial support of semiconductor wafer and laser cladding preparation method of graphite rod ceramic coating

Abstract

The invention belongs to the technical field of laser cladding, provides a graphite rod ceramic coating for epitaxial support of a semiconductor wafer and a laser cladding preparation method of the graphite rod ceramic coating, and is used for solving the problems of low bonding strength, low density and the like of a ceramic layer on the surface of an existing graphite substrate. The graphite rod ceramic coating for epitaxial supporting of the semiconductor wafer comprises a graphite substrate, and a transition layer, a ceramic middle layer and a ceramic functional surface layer are sequentially arranged on the outer side of the graphite substrate. According to the method, the bonding strength between the ceramic coating and the graphite rod substrate can be improved, meanwhile, the problems of pores, cracks and the like of the ceramic coating are effectively solved, the density of the ceramic coating is finally improved, the high insulation, high wear resistance and high cleanliness of the ceramic coating are improved, and the method is suitable for high-end semiconductor manufacturing.

Description

Technical Field

[0001] This invention belongs to the field of laser cladding technology, specifically relating to a graphite rod ceramic coating for semiconductor wafer epitaxial support and its laser cladding preparation method. Background Technology

[0002] Semiconductor wafer epitaxial growth supports require the use of graphite rods, and a ceramic layer needs to be deposited on the surface of these graphite rods (graphite substrate). In the semiconductor field, the main purposes of adding a ceramic layer are as follows: Preventing contamination and improving purity: Graphite itself is a conductive material. At high temperatures (such as in CVD, MOCVD, epitaxial growth, and single-crystal silicon growth furnaces), it releases trace amounts of dust or impurity atoms (such as metal ions). These impurities may contaminate semiconductor materials (such as silicon and GaN). Ceramic layers (such as silicon carbide (SiC), boron nitride (BN), and alumina (Al2O3) have high chemical inertness and can effectively prevent direct contact between the graphite substrate and the process atmosphere, preventing impurities from migrating into the wafer or reaction chamber.

[0003] Oxidation and corrosion resistance: Graphite is easily oxidized in high-temperature, oxygen-containing environments, leading to component wear, particle formation, and affecting process stability. The ceramic layer provides a dense physical barrier, significantly improving the service life of graphite components in oxidizing or corrosive atmospheres (such as O2, Cl2, HCl, etc.).

[0004] Improved surface properties and cleanability: Ceramic coatings typically have a smoother, denser surface, reducing particle adhesion and making them easier to clean (e.g., by removing surface deposits through wet or dry etching), thereby extending the maintenance cycle of graphite components and reducing production costs.

[0005] Controlling electrical and thermal properties: Some ceramic coatings have specific resistivity or thermal conductivity, which can be used to adjust the electrothermal characteristics of graphite heaters, electrodes or supports to meet the uniformity requirements of special processes.

[0006] Mechanical protection: The coating enhances the hardness and abrasion resistance of the graphite surface, reducing mechanical damage during wafer or component contact during loading / unloading.

[0007] However, there are the following technical problems in setting an alumina ceramic layer on a graphite substrate (graphite rod): 1. The thermal expansion coefficients of graphite matrix and alumina ceramic are very different. Direct laser cladding is prone to cracking and peeling due to residual stress concentration. The coating is also prone to voids and through cracks, resulting in insufficient bonding strength and low density.

[0008] 2. Traditional coating processes suffer from high thermal stress and poor interfacial bonding, making it difficult to meet high-temperature stability and insulation performance standards.

[0009] 3. Existing surface strengthening technologies (plasma spraying, vapor deposition, laser cladding, etc.) have the following obvious drawbacks: (1) The bonding strength is low, mostly mechanical bonding, not metallurgical bonding, and it is prone to failure at high temperatures; (2) The coating has poor uniformity, high porosity, and insufficient high temperature resistance and insulation performance; (3) Without proper preheating and cooling processes, the graphite matrix is ​​prone to overheating damage, resulting in a high coating cracking rate; (4) It cannot meet the multiple requirements of high bonding strength, thick coating, high temperature resistance and high density. Summary of the Invention

[0010] To address the problems of low bonding strength and low density of existing ceramic layers on graphite substrates, this invention provides a graphite rod ceramic coating for semiconductor wafer epitaxial support and its laser cladding preparation method. This method can improve the bonding strength between the ceramic layer and the graphite rod substrate, while effectively solving problems such as porosity and cracks in the ceramic layer. Ultimately, it improves the density of the ceramic layer, enhances its high insulation, high wear resistance, and high cleanliness, making it suitable for high-end semiconductor manufacturing.

[0011] To solve the technical problem, the technical solution adopted by this invention is as follows: A laser cladding method for preparing a ceramic coating on a graphite rod used as an epitaxial support for semiconductor wafers includes the following: (1) Pretreatment of graphite matrix.

[0012] (2) Preheating treatment of graphite matrix: The graphite matrix is ​​preheated by laser homogenization heating and medium frequency induction heating, and the area of ​​the graphite matrix to be clad is heated to 800-1000℃.

[0013] (3) Cladding transition layer: Ti powder is clad onto the surface of the preheated graphite matrix by coaxial powder feeding to form a transition layer with a thickness of 200-500μm.

[0014] (4) Ceramic intermediate layer: Intermediate powder is clad on the Ti transition layer by coaxial powder feeding to form a ceramic intermediate layer.

[0015] (5) Ceramic functional surface layer: Functional powder is clad onto the intermediate layer of ceramic by coaxial powder feeding to form a ceramic functional surface layer.

[0016] (6) Step cooling: After the ceramic functional surface layer is completed, a step cooling method is used to cool it to complete the preparation of the graphite matrix ceramic coating.

[0017] In some embodiments, the Ti powder in step (3) has a purity of ≥99.9% and a particle size of 50-150 μm.

[0018] In some embodiments, when laser cladding is performed in step (3), the laser power is 1200-1800W, the scanning speed is 200-5000mm / min, and the powder feeding rate is 4-9g / min.

[0019] In some embodiments, the intermediate powder in step (4) is composed of yttrium oxide powder and aluminum oxide powder, wherein the mass fraction of the yttrium oxide powder is 0.5-0.9%; the purity of the aluminum oxide powder is ≥99.99% and the particle size is 30-100μm; and the thickness of the ceramic intermediate layer composed of the intermediate powder is 50-100μm.

[0020] In some embodiments, when laser cladding is performed in step (4), the laser power is 1500-2000W, the scanning speed is 300-600mm / min, and the powder feeding rate is 10-22g / min.

[0021] In some embodiments, the functional powder in step (5) is composed of yttrium oxide powder and aluminum oxide powder, wherein the mass fraction of the yttrium oxide powder is 1.7-2.5%; the purity of the aluminum oxide powder is ≥99.99% and the particle size is 30-100μm; and the thickness of the ceramic functional surface layer composed of the functional powder is 300-900μm.

[0022] In some embodiments, when laser cladding is performed in step (5), the laser power is 1600-2500W, the scanning speed is 300-800mm / min, and the powder feeding rate is 11-28g / min.

[0023] In some embodiments, during step (6) of the stepped cooling process, the temperature is cooled to room temperature at a rate of 5-10°C / min under the protection of argon gas with a purity of ≥99.999% and a flow rate of 5-15 L / min.

[0024] The present invention also provides a graphite rod ceramic coating for semiconductor wafer epitaxial support, comprising a graphite substrate, wherein a transition layer, a ceramic intermediate layer and a ceramic functional surface layer are sequentially disposed on the outer side of the graphite substrate.

[0025] In some embodiments, the transition layer is formed by laser cladding of Ti powder onto a graphite substrate, and the thickness of the transition layer is 200-500 μm.

[0026] In some embodiments, the ceramic intermediate layer is formed by laser cladding of intermediate powder onto the transition layer. The intermediate powder is composed of yttrium oxide powder and aluminum oxide powder, and the mass fraction of the yttrium oxide powder is 0.5-0.9%. The thickness of the ceramic intermediate layer is 50-100 μm.

[0027] In some embodiments, the ceramic functional surface layer is formed by laser cladding of functional powder onto the ceramic intermediate layer; the functional powder is composed of yttrium oxide powder and aluminum oxide powder, with the mass fraction of yttrium oxide powder being 1.7-2.5%; the thickness of the ceramic functional surface layer is 300-900 μm.

[0028] Compared with the prior art, the present invention has the following beneficial effects: The present invention relates to a graphite rod ceramic coating for semiconductor wafer epitaxial support and its laser cladding preparation method. This method utilizes a three-layer gradient structure consisting of a graphite substrate (such as a graphite rod), a Ti transition layer, an alumina ceramic intermediate layer, and an alumina ceramic functional surface layer. The interface elements are gradient-distributed, and the heat-affected zone of the substrate is <0.3 mm. This completely solves the problem of thermal expansion mismatch between the graphite substrate and the ceramic, thus preventing the ceramic coating from cracking or peeling.

[0029] The preparation process employs laser homogenization preheating and stepped cooling techniques to significantly reduce thermal stress, improve coating bonding strength, and achieve stable metallurgical bonding.

[0030] The ceramic coating of this invention has no obvious pores or cracks, and has the characteristics of high insulation, high wear resistance and high cleanliness, making it suitable for use in high-end semiconductor manufacturing.

[0031] The process of this invention is stable and highly controllable, and can laser clad ceramic coatings on graphite substrates (graphite rods) of different sizes, thus having high promotion and application value. Attached Figure Description

[0032] Figure 1 This is a cross-sectional schematic diagram of the ceramic coating on the graphite rod used for semiconductor wafer epitaxial support according to the present invention.

[0033] Reference numerals: 1. Graphite matrix; 2. Transition layer; 3. Ceramic intermediate layer; 4. Ceramic functional surface layer. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are some, but not all, of the embodiments of the present invention. The following embodiments are only for specific illustration of the implementation methods of the present invention and do not limit the scope of protection of the present invention.

[0035] Combined with appendix Figure 1 The laser cladding method for preparing a ceramic coating on a graphite rod used as a semiconductor wafer epitaxial support according to the present invention includes the following: (1) Pretreatment of graphite matrix; The pretreatment mainly involves cleaning the graphite matrix (graphite rod), which can be understood by those skilled in the art. For example, the surface of the graphite matrix is ​​ultrasonically cleaned with anhydrous ethanol to remove oil and impurities, and then dried for later use.

[0036] In some embodiments, the graphite substrate is a graphite rod, for example, a graphite rod used for epitaxial support of a semiconductor wafer. In some embodiments, the graphite substrate is graphite of other shapes.

[0037] (2) Preheating of the graphite substrate: The graphite substrate is preheated using laser co-source heating and medium-frequency induction heating to heat the area to be clad to 800-1000℃. In some embodiments, a 6KW semiconductor laser with a fiber core diameter of 600μm is used to preheat the area to be clad. The temperature fluctuation is ≤50℃. The preheating treatment reduces the interface temperature gradient and thermal stress, while induction heating is used simultaneously to heat the graphite substrate (graphite rod) to ensure stable and uniform heating temperature.

[0038] (3) Cladding transition layer: Ti powder is laser-clad onto the surface of the preheated graphite matrix using a coaxial powder feeding method to form a transition layer with a thickness of 200-500μm.

[0039] (4) Ceramic intermediate layer: The intermediate powder is laser-clad on the Ti transition layer by using coaxial powder feeding to form a ceramic intermediate layer.

[0040] (5) Ceramic functional surface layer: Functional powder is laser-clad onto the intermediate layer of ceramic by using coaxial powder feeding to form a ceramic functional surface layer.

[0041] (6) Step cooling: After the ceramic functional surface layer is completed, a step cooling method is used to cool the graphite substrate to complete the preparation of the ceramic coating.

[0042] In the specific implementation process, an argon atmosphere chamber is used during laser cladding. The chamber is filled with argon gas, so that the oxygen content in the chamber is less than 0.1 ppm.

[0043] While those skilled in the art understand that argon gas protection is necessary during laser cladding, argon atmosphere chambers (also known as argon protection chambers) are required for situations where materials are highly susceptible to oxidation, the quality of the cladding layer (such as porosity and inclusions) is critical, and cladding in air would lead to serious defects. To ensure the quality of the ceramic coating, this invention utilizes an argon atmosphere chamber for protection.

[0044] In some embodiments, the Ti powder in step (3) has a purity ≥99.9% and a particle size of 50-150 μm. Ti metal powder is used as a transition material between the graphite and ceramic layers. Ti diffuses at the graphite interface to form TiC and TiAl intermetallic compounds, achieving a strong metallurgical bond.

[0045] In some embodiments, when laser cladding is performed in step (3), the laser power is 1200-1800W, the scanning speed is 200-5000mm / min, and the powder feeding rate is 4-9g / min.

[0046] In some embodiments, the intermediate powder in step (4) is composed of yttrium oxide powder and aluminum oxide powder, wherein the mass fraction of the yttrium oxide powder is 0.5-0.9%; the purity of the aluminum oxide powder is ≥99.99%, the particle size is 30-100 μm, and the thickness of the ceramic intermediate layer composed of the intermediate powder is 50-100 μm. The ceramic intermediate layer further alleviates thermal expansion mismatch (i.e., alleviates the phenomenon of inconsistent thermal expansion due to different coefficients of thermal expansion). Among them, yttrium oxide can stabilize the Al2O3 crystal form, inhibit high-temperature phase transformation, reduce residual stress in the coating, improve toughness and high-temperature creep resistance, and prevent the coating from cracking and peeling during long-term high-temperature service.

[0047] In some embodiments, when laser cladding is performed in step (4), the laser power is 1500-2000W, the scanning speed is 300-600mm / min, and the powder feeding rate is 10-22g / min.

[0048] In some embodiments, the functional powder in step (5) is composed of yttrium oxide powder and aluminum oxide powder, wherein the mass fraction of the yttrium oxide powder is 1.7-2.5%; the purity of the aluminum oxide powder is ≥99.99%, the particle size is 30-100 μm, and the thickness of the ceramic functional surface layer composed of the functional powder is 300-900 μm. The ceramic functional surface layer is clad onto the ceramic intermediate layer to form the final working layer. This ensures the core properties of high temperature resistance, insulation, and wear resistance.

[0049] In some embodiments, when laser cladding is performed in step (5), the laser power is 1600-2500W, the scanning speed is 300-800mm / min, and the powder feeding rate is 11-28g / min.

[0050] In some embodiments, during step (6) of the stepped cooling process, the temperature is reduced to room temperature at a rate of 5-10°C / min under the protection of argon gas with a purity ≥99.999% and a flow rate of 5-15 L / min. This step-cooling process releases residual stress and prevents the coating from cracking.

[0051] The present invention also provides a graphite rod ceramic coating for semiconductor wafer epitaxial support, comprising a graphite substrate, wherein a transition layer, a ceramic intermediate layer and a ceramic functional surface layer are sequentially disposed on the outer side of the graphite substrate.

[0052] In some embodiments, the total thickness of the transition layer, the ceramic intermediate layer, and the ceramic functional surface layer is 0.6-1.5 mm.

[0053] In some embodiments, the transition layer is formed by laser cladding of Ti powder onto a graphite substrate, and the thickness of the transition layer is 200-500 μm.

[0054] In some embodiments, the ceramic intermediate layer is formed by laser cladding of intermediate powder onto the transition layer. The intermediate powder is composed of yttrium oxide powder and aluminum oxide powder, and the mass fraction of the yttrium oxide powder is 0.5-0.9%. The thickness of the ceramic intermediate layer is 50-100 μm.

[0055] In some embodiments, the ceramic functional surface layer is formed by laser cladding of functional powder onto the ceramic intermediate layer; the functional powder is composed of yttrium oxide powder and aluminum oxide powder, with the mass fraction of yttrium oxide powder being 1.7-2.5%; the thickness of the ceramic functional surface layer is 300-900 μm.

[0056] In summary, this invention can improve the bonding strength between the ceramic layer and the graphite rod substrate, while effectively solving problems such as porosity and cracks in the ceramic layer, ultimately improving the density of the ceramic layer, and enhancing its high insulation, high wear resistance and high cleanliness, making it suitable for high-end semiconductor manufacturing. Example 1

[0057] The graphite rod ceramic coating for semiconductor wafer epitaxial support in this embodiment includes a graphite substrate. A transition layer, a ceramic intermediate layer, and a ceramic functional surface layer are sequentially disposed on the outer side of the graphite substrate. The transition layer is formed by laser cladding of Ti powder onto the graphite substrate, and the thickness of the transition layer is 200-500 μm. The intermediate powder is composed of yttrium oxide powder and aluminum oxide powder, with the mass fraction of the yttrium oxide powder being 0.5-0.9%. The thickness of the ceramic intermediate layer is 50-100 μm. The ceramic functional surface layer is formed by laser cladding of functional powder onto the ceramic intermediate layer, with the functional powder being composed of yttrium oxide powder and aluminum oxide powder, and the mass fraction of the yttrium oxide powder being 1.7-2.5%. The thickness of the ceramic functional surface layer is 300-900 μm. Example 2

[0058] The graphite rod ceramic coating for semiconductor wafer epitaxial support in this embodiment includes a graphite substrate. A transition layer, a ceramic intermediate layer, and a ceramic functional surface layer are sequentially disposed on the outer side of the graphite substrate. The transition layer is formed by laser cladding of Ti powder onto the graphite substrate, and the thickness of the transition layer is 200-500 μm. The intermediate powder is composed of yttrium oxide powder and aluminum oxide powder, with the mass fraction of the yttrium oxide powder being 0.5%. The thickness of the ceramic intermediate layer is 50-100 μm. The ceramic functional surface layer is formed by laser cladding of functional powder onto the ceramic intermediate layer, with the functional powder composed of yttrium oxide powder and aluminum oxide powder, and the mass fraction of the yttrium oxide powder being 1.7%. The thickness of the ceramic functional surface layer is 300-900 μm. Example 3

[0059] The graphite rod ceramic coating for semiconductor wafer epitaxial support in this embodiment includes a graphite substrate. A transition layer, a ceramic intermediate layer, and a ceramic functional surface layer are sequentially disposed on the outer side of the graphite substrate. The transition layer is formed by laser cladding of Ti powder onto the graphite substrate, and the thickness of the transition layer is 200-500 μm. The intermediate powder is composed of yttrium oxide powder and aluminum oxide powder, with the mass fraction of the yttrium oxide powder being 0.9%. The thickness of the ceramic intermediate layer is 50-100 μm. The ceramic functional surface layer is formed by laser cladding of functional powder onto the ceramic intermediate layer, with the functional powder composed of yttrium oxide powder and aluminum oxide powder, and the mass fraction of the yttrium oxide powder being 2.5%. The thickness of the ceramic functional surface layer is 300-900 μm. Example 4

[0060] The graphite rod ceramic coating for semiconductor wafer epitaxial support in this embodiment includes a graphite substrate. A transition layer, a ceramic intermediate layer, and a ceramic functional surface layer are sequentially disposed on the outer side of the graphite substrate. The transition layer is formed by laser cladding of Ti powder onto the graphite substrate, and the thickness of the transition layer is 200-500 μm. The intermediate powder is composed of yttrium oxide powder and aluminum oxide powder, with the mass fraction of the yttrium oxide powder being 0.7%. The thickness of the ceramic intermediate layer is 50-100 μm. The ceramic functional surface layer is formed by laser cladding of functional powder onto the ceramic intermediate layer, with the functional powder composed of yttrium oxide powder and aluminum oxide powder, and the mass fraction of the yttrium oxide powder being 2.1%. The thickness of the ceramic functional surface layer is 300-900 μm. Example 5

[0061] The graphite rod ceramic coating for semiconductor wafer epitaxial support in this embodiment includes a graphite substrate. A transition layer, a ceramic intermediate layer, and a ceramic functional surface layer are sequentially disposed on the outer side of the graphite substrate. The transition layer is formed by laser cladding of Ti powder onto the graphite substrate, and the thickness of the transition layer is 200-500 μm. The intermediate powder is composed of yttrium oxide powder and aluminum oxide powder, with the mass fraction of the yttrium oxide powder being 0.8%. The thickness of the ceramic intermediate layer is 50-100 μm. The ceramic functional surface layer is formed by laser cladding of functional powder onto the ceramic intermediate layer, with the functional powder composed of yttrium oxide powder and aluminum oxide powder, and the mass fraction of the yttrium oxide powder being 2.3%. The thickness of the ceramic functional surface layer is 300-900 μm. Example 6

[0062] The graphite rod ceramic coating for semiconductor wafer epitaxial support in this embodiment includes a graphite substrate. A transition layer, a ceramic intermediate layer, and a ceramic functional surface layer are sequentially disposed on the outer side of the graphite substrate. The transition layer is formed by laser cladding of Ti powder onto the graphite substrate, and the thickness of the transition layer is 200-500 μm. The intermediate powder is composed of yttrium oxide powder and aluminum oxide powder, with the mass fraction of the yttrium oxide powder being 0.6%. The thickness of the ceramic intermediate layer is 50-100 μm. The ceramic functional surface layer is formed by laser cladding of functional powder onto the ceramic intermediate layer, with the functional powder composed of yttrium oxide powder and aluminum oxide powder, and the mass fraction of the yttrium oxide powder being 2.5%. The thickness of the ceramic functional surface layer is 300-900 μm. Example 7

[0063] The present invention provides a laser cladding method for preparing a ceramic coating on a graphite rod used as a semiconductor wafer epitaxial support, comprising: (1) Pretreatment of graphite matrix.

[0064] (2) Preheating treatment of graphite matrix: The graphite matrix is ​​preheated by laser homogenization heating and medium frequency induction heating, and the area of ​​the graphite matrix to be clad is heated to 800-1000℃.

[0065] (3) Cladding transition layer: Ti powder is clad onto the surface of the preheated graphite matrix by coaxial powder feeding to form a transition layer with a thickness of 200-500μm; the purity of the Ti powder is ≥99.9% and the particle size is 50-150μm; when laser cladding is performed, the laser power is 1200-1800W, the scanning speed is 200-5000mm / min, and the powder feeding rate is 4-9g / min.

[0066] (4) Ceramic Intermediate Layer: Intermediate powder is laser-clad onto the Ti transition layer using a coaxial powder feeding method to form a ceramic intermediate layer. The intermediate powder consists of yttrium oxide powder and aluminum oxide powder, wherein the mass fraction of the yttrium oxide powder is 0.5-0.9%; the purity of the aluminum oxide powder is ≥99.99%, the particle size is 30-100μm, and the thickness of the ceramic intermediate layer composed of the intermediate powder is 50-100μm; during laser cladding, the laser power is 1500-2000W, the scanning speed is 300-600mm / min, and the powder feeding rate is 10-22g / min.

[0067] (5) Ceramic functional surface layer: Functional powder is clad onto the ceramic intermediate layer by coaxial powder feeding to form a ceramic functional surface layer; the functional powder is composed of yttrium oxide powder and aluminum oxide powder, the mass fraction of yttrium oxide powder is 1.7-2.5%; the purity of aluminum oxide powder is ≥99.99% and the particle size is 30-100μm, and the thickness of the ceramic functional surface layer composed of functional powder is 300-900μm; during laser cladding, the laser power is 1600-2500W, the scanning speed is 300-800mm / min, and the powder feeding rate is 11-28g / min.

[0068] (6) Step cooling: After completing the ceramic functional surface layer, a step cooling method is used to cool the graphite substrate to complete the preparation of the ceramic coating. Under the protection of argon gas with a purity ≥99.999% and a flow rate of 5-15 L / min, the temperature is cooled to room temperature at a rate of 5-10 °C / min. This step cooling method releases residual stress and prevents the coating from cracking. Steps (2) to (6) are all carried out in an argon atmosphere chamber and the argon gas is used for gas protection, so that the oxygen content in the argon atmosphere chamber is less than 0.1 ppm.

[0069] Before proceeding to step (2), an argon atmosphere chamber should be prepared and filled with argon gas so that the oxygen content in the argon atmosphere chamber is less than 0.1 ppm.

[0070] It should be understood that the above description of the preferred embodiments is quite detailed, but it should not be considered as a limitation on the scope of protection of this invention. Those skilled in the art, under the guidance of this invention, can make substitutions or modifications without departing from the scope of protection of the claims of this invention, and all such substitutions or modifications fall within the scope of protection of this invention. The scope of protection of this invention should be determined by the appended claims.

Claims

1. A graphite rod ceramic coating for semiconductor wafer epitaxial support, characterized in that, It includes a graphite matrix, and a transition layer, a ceramic intermediate layer and a ceramic functional surface layer are sequentially disposed on the outer side of the graphite matrix.

2. The graphite rod ceramic coating for semiconductor wafer epitaxial support according to claim 1, characterized in that, The transition layer is formed by laser cladding of Ti powder onto a graphite substrate, and the thickness of the transition layer is 200-500 μm.

3. The graphite rod ceramic coating for semiconductor wafer epitaxial support according to claim 1, characterized in that, The ceramic intermediate layer is formed by laser cladding of intermediate powder onto the transition layer. The intermediate powder is composed of yttrium oxide powder and aluminum oxide powder, and the mass fraction of the yttrium oxide powder is 0.5-0.9%. The thickness of the ceramic intermediate layer is 50-100 μm.

4. The graphite rod ceramic coating for semiconductor wafer epitaxial support according to claim 1, characterized in that, The ceramic functional surface layer is formed by laser cladding of functional powder onto the ceramic intermediate layer; the functional powder is composed of yttrium oxide powder and aluminum oxide powder, with the mass fraction of yttrium oxide powder being 1.7-2.5%; the thickness of the ceramic functional surface layer is 300-900 μm.

5. A method for laser cladding a ceramic coating on a graphite rod used as an epitaxial support for a semiconductor wafer as described in any one of claims 1-4, characterized in that, include: (1) Pretreatment of graphite matrix; (2) Preheating treatment of graphite matrix: The graphite matrix is ​​preheated using laser homogenization heating and medium frequency induction heating to heat the area of ​​the graphite matrix to be clad to 800-1000℃; (3) Cladding transition layer: Ti powder is laser-clad onto the surface of the preheated graphite substrate using a coaxial powder feeding method to form a transition layer with a thickness of 200-500μm; (4) Ceramic intermediate layer: Intermediate powder is laser-clad onto the Ti transition layer using a coaxial powder feeding method to form a ceramic intermediate layer; (5) Ceramic functional surface layer: Functional powder is laser-clad onto the intermediate layer of ceramic using a coaxial powder feeding method to form a ceramic functional surface layer; (6) Step cooling: After the ceramic functional surface layer is completed, a step cooling method is used to cool it to complete the preparation of the graphite matrix ceramic coating.

6. The laser cladding method for preparing a ceramic coating on a graphite rod used as an epitaxial support for semiconductor wafers according to claim 5, characterized in that, The intermediate powder in step (4) is composed of yttrium oxide powder and aluminum oxide powder. The mass fraction of the yttrium oxide powder is 0.5-0.9%; the purity of the aluminum oxide powder is ≥99.99% and the particle size is 30-100μm. The thickness of the ceramic intermediate layer composed of the intermediate powder is 50-100μm.

7. The laser cladding method for preparing a ceramic coating on a graphite rod used as an epitaxial support for semiconductor wafers according to claim 6, characterized in that, When performing laser cladding in step (4), the laser power is 1500-2000W, the scanning speed is 300-600mm / min, and the powder feeding rate is 10-22g / min.

8. The laser cladding method for preparing a ceramic coating on a graphite rod used as an epitaxial support for semiconductor wafers according to claim 5, characterized in that, The functional powder in step (5) is composed of yttrium oxide powder and aluminum oxide powder. The mass fraction of the yttrium oxide powder is 1.7-2.5%. The purity of the aluminum oxide powder is ≥99.99%, the particle size is 30-100μm, and the thickness of the ceramic functional surface layer composed of the functional powder is 300-900μm.

9. The laser cladding method for preparing a ceramic coating on a graphite rod used as an epitaxial support for semiconductor wafers according to claim 8, characterized in that, When performing laser cladding in step (5), the laser power is 1600-2500W, the scanning speed is 300-800mm / min, and the powder feeding rate is 11-28g / min.

10. The laser cladding method for preparing a ceramic coating on a graphite rod used as an epitaxial support for semiconductor wafers according to claim 5, characterized in that, During the step cooling in step (6), under the protection of argon gas with a purity ≥99.999% and a flow rate of 5-15 L / min, the temperature is cooled to room temperature at a rate of 5-10 °C / min.

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