A method for preparing a composite coating for a graphite component, the graphite component, and the graphite crucible.

Abstract

This invention relates to the field of semiconductor technology, and particularly to a method for preparing a composite coating for a graphite component, a graphite component, and a graphite crucible. The method includes a TaN coating and a TaC coating. The TaN coating is positioned between the graphite substrate and the TaC coating, acting as a transition layer. This effectively reduces the significant thermal stress caused by the large difference in thermal expansion coefficients between the graphite substrate and the TaC coating, maintaining the stability of the coating on the graphite component surface and improving the bonding strength between the coating and the graphite substrate. Furthermore, during the growth of N-type silicon carbide crystals using the graphite crucible with the composite coating, the nitrogen element in the TaN coating is replaced by carbon elements from the environment. The generated nitrogen gas is released from the inner wall of the isodiameter ring towards the crystal edge, which helps improve the nitrogen uniformity in the N-type silicon carbide crystal growth environment. This reduces the formation of polymorphism, defects, and cracks at the crystal edge, and also reduces the roughness of the generated crystal edge and the low-profile morphology of the intermediate protruding edges.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a method for preparing a composite coating for a graphite component, a graphite component, and a graphite crucible. Background Technology

[0002] SiC crystal, as a high-performance third-generation semiconductor material, holds a prominent position in the semiconductor technology field. However, during SiC crystal growth, the atmosphere in the growth environment has a severe corrosive effect on the graphite components, leading to their loss and contamination of the SiC crystal, thus affecting the growth quality. To prevent corrosion of the graphite components during SiC crystal growth, a TaC coating is used to protect them. The TaC coating has a high melting point and corrosion resistance.

[0003] Currently, high-temperature chemical vapor deposition (CVD) is commonly used to prepare TaC coatings, resulting in low-stress, crack-free coatings. However, CVD suffers from drawbacks such as low deposition rate, long preparation cycle, and high process cost. Furthermore, the obtained TaC coatings may develop cracks during preparation and application due to thermal stress, and may even detach easily, failing to meet the requirements for protecting graphite substrates. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a method for preparing a composite coating of graphite components, a graphite component, and a graphite crucible.

[0005] To achieve the above objectives, the present invention provides a method for preparing a composite coating for graphite components, comprising:

[0006] A nitrogen-tantalum coating liquid, a carbon-tantalum coating liquid, and a graphite component are provided, wherein the graphite substrate on the surface of the graphite component is exposed;

[0007] After the nitrogen-tantalum coating liquid is applied to the surface of the graphite component, a first sintering is performed to form a TaN coating.

[0008] After the carbon-tantalum coating liquid is applied to the surface of the TaN coating, a second sintering is performed to form a TaC coating. The TaN coating and the TaC coating form a composite coating, and finally a graphite component with the composite coating is obtained. The coefficient of thermal expansion of TaN is between that of the graphite substrate and TaC.

[0009] Optionally, the preparation steps of the nitrogen-tantalum coating liquid include:

[0010] Provide the first silicon-containing powder and carbon powder;

[0011] The silicon-containing powder and the carbon powder are subjected to a third sintering under a nitrogen atmosphere to obtain a nitrogen-silicon synthetic powder body.

[0012] The nitrogen-silicon synthesis powder body is crushed to obtain nitrogen-silicon synthesis powder with a certain particle size;

[0013] The nitrogen-tantalum coating liquid is obtained by mixing the first organic binder, the first organic solvent, the first tantalum-containing powder, and the nitrogen-silicon synthetic powder.

[0014] Optionally, the first silicon-containing powder includes one or two of SiO2 and Si, the first tantalum-containing powder includes one or more of tantalum powder, tantalum oxide powder, and tantalum chloride powder, the temperature range for the third sintering of the first silicon-containing powder and the carbon powder under a nitrogen atmosphere is 1000℃~1800℃, and the time range for the third sintering of the first silicon-containing powder and the carbon powder under a nitrogen atmosphere is 1h~5h.

[0015] Optionally, the main component of the nitrogen-silicon synthetic powder is Si. x N y The particle size range of nitrogen-silicon synthetic powder with a certain particle size is 1μm to 5μm.

[0016] Optionally, the carbon-tantalum coating liquid includes: a second silicon-containing powder, carbon powder, and a second tantalum-containing powder; the particle size range of the second silicon-containing powder, the carbon powder, and the second tantalum-containing powder is 1μm to 5μm; the second silicon-containing powder includes one or two of SiO2 and Si, and the second tantalum-containing powder includes one or more of tantalum powder, tantalum oxide powder, and tantalum chloride powder.

[0017] Optionally, the first sintering temperature range is 1200℃~2000℃ and the first sintering time range is 1h~50h; the second sintering temperature range is 1600℃~2400℃ and the second sintering time range is 1h~50h.

[0018] Optionally, the TaC coating has a certain porosity, allowing the nitrogen gas generated by the reaction of the TaN coating to be released from the pores of the TaC coating.

[0019] The present invention also provides a graphite component with a composite coating, comprising a graphite component and a TaN coating and a TaC coating located on the surface of the graphite component, wherein the TaN coating is attached to the surface of a graphite substrate, and the TaC coating is attached to the surface of the TaN coating, wherein the coefficient of thermal expansion of TaN is between that of the graphite substrate and the coefficient of thermal expansion of TaC.

[0020] Optionally, the thickness of the TaN coating ranges from 15 μm to 40 μm, and the thickness of the TaC coating ranges from 10 μm to 30 μm.

[0021] The present invention also provides a graphite crucible for N-type crystal growth, comprising a graphite crucible and a TaN coating and a TaC coating located on the inner surface of the graphite crucible, wherein the TaN coating is attached to the inner surface of the graphite crucible and the TaC coating is attached to the surface of the TaN coating, wherein the coefficient of thermal expansion of TaN is between that of the graphite substrate and the coefficient of thermal expansion of TaC.

[0022] In summary, the advantages and beneficial effects of the present invention are as follows:

[0023] This invention provides a method for preparing a composite coating for graphite components, a graphite component, and a graphite crucible. The coating includes a TaN coating and a TaC coating. The coefficient of thermal expansion of TaN is between that of the graphite substrate and the TaC coating. Placing the TaN coating between the graphite substrate and the TaC coating acts as a transition, effectively reducing the large thermal stress caused by the significant difference in the coefficients of thermal expansion between the graphite substrate and the TaC coating, maintaining the stability of the coating on the surface of the graphite component, and improving the bonding strength between the coating and the graphite substrate.

[0024] Furthermore, during the growth of N-type crystals using a graphite crucible with a composite coating, the graphite crucible, other graphite components, and silicon carbide powder serve as carbon sources, displacing the nitrogen element in the TaN coating with carbon elements in the growth environment. The generated nitrogen gas is released from the inner wall of the equal-diameter ring towards the crystal edge, which helps to improve the nitrogen uniformity in the N-type crystal growth environment. This avoids the situation in conventional N-type crystal growth where the concentration of nitrogen element at the crystal edge is lower than that at the crystal center, thereby reducing the formation of polymorphism, polytypes, defects, and cracks at the crystal edge. It also reduces the roughness of the generated crystal edge and the low-profile morphology of the crystal's central protrusion. Attached Figure Description

[0025] Figure 1 This is a schematic flowchart illustrating a method for preparing a composite coating for a graphite component according to an embodiment of the present invention. Detailed Implementation

[0026] The coefficient of thermal expansion of the graphite substrate is 2.1 × 10⁻⁶. -6 / K~2.6×10 -6 / K, the coefficient of thermal expansion of TaC is 6.3×10 -6 The large difference in the coefficient of thermal expansion between the TaC coating and the graphite substrate leads to repeated high and low temperature transitions during the preparation of the TaC coating on the graphite substrate and the application of graphite components with the TaC coating. This results in thermal stress at the interface between the TaC coating and the graphite substrate. Due to the large difference in the coefficient of thermal expansion between the TaC coating and the graphite substrate, the bonding strength between the TaC coating and the graphite substrate is low. The TaC coating may crack due to thermal stress, or even easily fall off, failing to meet the requirements for protecting the graphite substrate.

[0027] To facilitate understanding by those skilled in the art, the present invention will be further described in detail below with reference to specific embodiments.

[0028] This invention provides a method for preparing a composite coating for graphite components, such as... Figure 1 As shown, it includes:

[0029] Step S10: Provide nitrogen-tantalum coating liquid, carbon-tantalum coating liquid, and graphite component, wherein the graphite substrate on the surface of the graphite component is exposed;

[0030] Step S20: After the nitrogen-tantalum coating liquid is applied to the surface of the graphite component, a first sintering is performed to form a TaN coating.

[0031] Step S30: After the carbon-tantalum coating liquid is applied to the surface of the TaN coating, a second sintering is performed to form a TaC coating. The TaN coating and the TaC coating form a composite coating, and finally a graphite component with the composite coating is obtained. The coefficient of thermal expansion of TaN is between that of the graphite substrate and TaC.

[0032] Specifically, in step S10, a nitrogen-tantalum coating liquid, a carbon-tantalum coating liquid, and a graphite component are provided, wherein the graphite substrate on the surface of the graphite component is exposed.

[0033] In this embodiment of the invention, the preparation steps of the nitrogen-tantalum coating liquid include:

[0034] Step S111: Provide a first silicon-containing powder and carbon powder;

[0035] In this embodiment of the invention, the first silicon-containing powder is SiO2.

[0036] In other embodiments, the first silicon-containing powder is Si or a mixture of SiO2 and Si.

[0037] In this embodiment of the invention, the amount of silicon in the first silicon-containing powder ranges from 0.2 mol to 1.0 mol, and the amount of carbon powder ranges from 0.3 mol to 1.2 mol.

[0038] In this embodiment of the invention, the first silicon-containing powder and carbon powder are mixed by vibration using a vibration instrument before subsequent third sintering, and the vibration mixing time range is 20 min to 50 min.

[0039] Step S112: The first silicon-containing powder and the carbon powder are subjected to a third sintering under a nitrogen atmosphere to obtain a nitrogen-silicon synthetic powder body;

[0040] In this embodiment of the invention, the mixed first silicon-containing powder and the carbon powder are placed in a silicon carbide crucible for a third sintering.

[0041] In this embodiment of the invention, the temperature range for the third sintering of the first silicon-containing powder and the carbon powder under a nitrogen atmosphere is 1000℃~1800℃, and the time range for the third sintering of the first silicon-containing powder and the carbon powder under a nitrogen atmosphere is 1h~5h.

[0042] In this embodiment of the invention, during the third sintering, the first silicon-containing powder, the carbon powder, and nitrogen gas undergo a chemical reaction, namely SiO2 + C + N2 → Si x N y +CO, the nitrogen-silicon synthetic powder body obtained after the third sintering is divided into Si x N y .

[0043] Step S113: The nitrogen-silicon synthesis powder body is crushed to obtain nitrogen-silicon synthesis powder with a certain particle size;

[0044] In this embodiment of the invention, the nitrogen-silicon synthetic powder body is crushed, ground, and then sieved to obtain nitrogen-silicon synthetic powder with a certain particle size, wherein the particle size range of the nitrogen-silicon synthetic powder with a certain particle size is 1μm to 5μm.

[0045] Step S114: Mix the first organic binder, the first organic solvent, the first tantalum-containing powder, and the nitrogen-silicon synthesis powder to obtain the nitrogen-tantalum coating liquid.

[0046] In this embodiment of the invention, the amount of tantalum in the first tantalum-containing powder in the nitrogen-tantalum coating liquid ranges from 1 mol to 10 mol, the mass of the nitrogen-silicon synthetic powder ranges from 1 g to 20 g, and the mass fraction of the first organic linker ranges from 0.01% to 0.1%.

[0047] In this embodiment of the invention, the first tantalum-containing powder is tantalum powder. In other embodiments, the first tantalum-containing powder is one or more of tantalum powder, tantalum oxide powder, and tantalum chloride powder.

[0048] In this embodiment of the invention, the first organic binder is gum arabic. In other embodiments, the first organic binder is epoxy resin, phenolic resin, or other suitable materials.

[0049] In this embodiment of the invention, the first organic solvent is an alcohol or ketone solvent, specifically one of ethanol, ethylene glycol, and acetone.

[0050] In this embodiment of the invention, when the first organic binder, the first organic solvent, the first tantalum-containing powder, and the nitrogen-silicon synthetic powder are mixed, grinding balls are added to ensure thorough mixing and shorten the mixing time.

[0051] In this embodiment of the invention, the grinding ball is a zirconia ball, and the grinding ball has two particle sizes: 3 mm and 5 mm, with the ratio of the two particle sizes ranging from 4:1 to 2:1.

[0052] In this embodiment of the invention, the mixing time for the first organic linker, the first organic solvent, the first tantalum-containing powder, and the nitrogen-silicon synthetic powder is 1h to 5h.

[0053] In this embodiment of the invention, the carbon-tantalum coating liquid includes a second silicon-containing powder, carbon powder, and a second tantalum-containing powder.

[0054] In this embodiment of the invention, the carbon-tantalum coating liquid further includes a second organic binder and a second organic solvent.

[0055] In this embodiment of the invention, the preparation steps of the carbon-tantalum coating liquid include:

[0056] Step S121: Provide a second silicon-containing powder, carbon powder, and a second tantalum-containing powder, and mix them uniformly to obtain a carbon-tantalum coating powder;

[0057] In this embodiment of the invention, the second silicon-containing powder is SiO2; in other embodiments, the second silicon-containing powder is Si or a mixture of SiO2 and Si.

[0058] In this embodiment of the invention, the second tantalum-containing powder is tantalum powder; in other embodiments, the second tantalum-containing powder is one or more of tantalum powder, tantalum oxide powder, and tantalum chloride powder.

[0059] In this embodiment of the invention, the particle size range of the second silicon-containing powder, the carbon powder, and the second tantalum-containing powder is 1 μm to 5 μm.

[0060] In this embodiment of the invention, the amount of silicon in the second silicon-containing powder of the carbon-tantalum coating powder ranges from 0.2 mol to 1.0 mol, the amount of carbon powder ranges from 0.3 mol to 1.2 mol, and the amount of tantalum in the second tantalum-containing powder ranges from 0.3 mol to 1.0 mol.

[0061] In this embodiment of the invention, the second silicon-containing powder, the carbon powder, and the second tantalum-containing powder are subjected to vibration crushing and grinding on a vibrating instrument to obtain carbon-tantalum coated powder with a particle size of 1μm to 5μm by sieving. The vibration crushing and grinding time on the vibrating instrument ranges from 20min to 50min.

[0062] Step S122: Provide a second organic linker and a second organic solvent;

[0063] In this embodiment of the invention, the second organic binder is gum arabic. In other embodiments, the second organic binder is epoxy resin, phenolic resin, or other suitable materials.

[0064] In this embodiment of the invention, the second organic solvent is an alcohol or ketone solvent, specifically one of ethanol, ethylene glycol, and acetone.

[0065] Step S123: After uniformly mixing the carbon-tantalum coating powder with the second organic binder and the second organic solvent, the carbon-tantalum coating liquid is obtained.

[0066] In this embodiment of the invention, the mass range of the carbon-tantalum coating powder in the carbon-tantalum coating liquid is 1g to 20g, and the mass fraction of the second organic linker is 0.01% to 0.5%.

[0067] In this embodiment of the invention, when the first organic binder, the first organic solvent, the first tantalum-containing powder, and the nitrogen-silicon synthetic powder are mixed, grinding balls are added to ensure thorough mixing and shorten the mixing time.

[0068] In this embodiment of the invention, the grinding ball is a zirconia ball, and the grinding ball has two particle sizes: 3 mm and 5 mm, with the ratio of the two particle sizes ranging from 4:1 to 2:1.

[0069] In this embodiment of the invention, the mixing time for the first organic linker, the first organic solvent, the first tantalum-containing powder, and the nitrogen-silicon synthetic powder is 1h to 5h.

[0070] In step S20, the nitrogen-tantalum coating liquid is applied to the surface of the graphite component, and then a first sintering is performed to form a TaN coating.

[0071] In this embodiment of the invention, the nitrogen-tantalum coating liquid is applied to the surface of the graphite component by one of brushing, spraying, or immersion.

[0072] In this embodiment of the invention, the method further includes: before the first sintering, coating the nitrogen-tantalum coating liquid onto the surface of the graphite component and then drying and curing it to form a nitrogen-tantalum pre-coating, wherein the drying and curing time for forming the nitrogen-tantalum pre-coating is 1h to 5h.

[0073] In this embodiment of the invention, the first sintering is vacuum sintering, the temperature range of the first sintering is 1200℃~2000℃, and the time range of the first sintering is 1h~50h.

[0074] During the first sintering process, the nitrogen-silicon composite powder in the nitrogen-tantalum coating liquid reacts with the first tantalum-containing powder to generate tantalum nitride, i.e., Si. x N y +Ta→TaSi x +TaN, forming a TaN coating on the surface of the graphite component.

[0075] The coefficient of thermal expansion of TaN is between that of graphite substrate and TaC. Placing the TaN coating between the graphite substrate and the TaC coating acts as a transition, effectively reducing the large thermal stress caused by the large difference in the coefficients of thermal expansion between the graphite substrate and the TaC coating, maintaining the stability of the coating on the surface of the graphite component, and improving the bonding strength between the coating and the graphite substrate.

[0076] In step S30, the carbon-tantalum coating liquid is applied to the surface of the TaN coating, and then a second sintering is performed to form a TaC coating. The TaN coating and the TaC coating form a composite coating, and finally a graphite component with the composite coating is obtained. The coefficient of thermal expansion of TaN is between that of the graphite substrate and the coefficient of thermal expansion of TaC.

[0077] In this embodiment of the invention, the carbon-tantalum coating liquid is applied to the surface of the TaN coating by brushing, spraying, or immersion.

[0078] In this embodiment of the invention, the method further includes: before the second sintering, coating the carbon-tantalum coating liquid onto the surface of the TaN coating and then drying and curing it to form a carbon-tantalum pre-coating, wherein the drying and curing time for forming the carbon-tantalum pre-coating is in the range of 1h to 5h.

[0079] In this embodiment of the invention, the second sintering is vacuum sintering, the temperature range of the second sintering is 1600℃~2400℃, and the time range of the second sintering is 1h~50h.

[0080] In this embodiment of the invention, the thickness of the TaN coating ranges from 15 μm to 40 μm, and the thickness of the TaC coating ranges from 10 μm to 30 μm.

[0081] In the process of growing N-type silicon carbide crystals using a graphite crucible with a composite coating, the graphite crucible, other graphite components, and silicon carbide powder in the growth environment serve as carbon sources, displacing the nitrogen element in the TaN coating to generate nitrogen gas. The generated nitrogen gas is released from the inner wall of the equal-diameter ring towards the edge of the silicon carbide crystal, which helps to improve the nitrogen uniformity in the N-type silicon carbide crystal growth environment. This avoids the situation in conventional N-type silicon carbide crystal growth where the concentration of nitrogen element at the edge of the silicon carbide crystal is lower than that at the center of the silicon carbide crystal. This reduces the formation of polymorphism, polytypes, defects, and cracks at the edge of the silicon carbide crystal, and also reduces the roughness of the edge of the generated silicon carbide crystal and the low morphology of the intermediate protruding edge of the silicon carbide crystal.

[0082] In this embodiment of the invention, the TaC coating has a certain porosity, so that the nitrogen gas released by the TaN coating during crystal growth is released through the voids in the TaC coating.

[0083] The present invention also provides a graphite component with a composite coating, comprising a graphite component and a TaN coating and a TaC coating located on the surface of the graphite component, wherein the TaN coating is attached to the surface of a graphite substrate, and the TaC coating is attached to the surface of the TaN coating, wherein the coefficient of thermal expansion of TaN is between that of the graphite substrate and the coefficient of thermal expansion of TaC.

[0084] In this embodiment of the invention, the thickness of the TaN coating ranges from 15 μm to 40 μm, and the thickness of the TaC coating ranges from 10 μm to 30 μm.

[0085] This invention also provides a graphite crucible for N-type crystal growth, comprising a graphite crucible and a TaN coating and a TaC coating located on the inner surface of the graphite crucible. The TaN coating is attached to the inner surface of the graphite crucible, and the TaC coating is attached to the surface of the TaN coating. The coefficient of thermal expansion of TaN is between that of the graphite substrate and the coefficient of thermal expansion of TaC.

[0086] Finally, it should be noted that any modification or equivalent substitution of some or all of the technical features based on the device structure and the technical solutions of the embodiments of the present invention, without departing from the corresponding technical solutions of the present invention, shall fall within the patent scope of the device structure and the embodiments of the present invention.

Claims

1. A method for preparing a composite coating for graphite components, characterized in that, include: A nitrogen-tantalum coating liquid, a carbon-tantalum coating liquid, and a graphite component are provided, wherein the graphite substrate on the surface of the graphite component is exposed; After the nitrogen-tantalum coating liquid is applied to the surface of the graphite component, a first sintering is performed to form a TaN coating. After the carbon-tantalum coating liquid is applied to the surface of the TaN coating, a second sintering is performed to form a TaC coating. The TaN coating and the TaC coating form a composite coating, and finally a graphite component with the composite coating is obtained. The coefficient of thermal expansion of TaN is between that of the graphite substrate and TaC. The preparation steps of the nitrogen-tantalum coating liquid include: providing a first silicon-containing powder and carbon powder; performing a third sintering of the silicon-containing powder and the carbon powder under a nitrogen atmosphere to obtain a nitrogen-silicon synthetic powder body; crushing the nitrogen-silicon synthetic powder body to obtain nitrogen-silicon synthetic powder of a certain particle size; and mixing a first organic binder, a first organic solvent, the first tantalum-containing powder, and the nitrogen-silicon synthetic powder to obtain the nitrogen-tantalum coating liquid.

2. The method for preparing a composite coating for graphite components as described in claim 1, characterized in that, The first silicon-containing powder includes one or two of SiO2 and Si, and the first tantalum-containing powder includes one or more of tantalum powder, tantalum oxide powder, and tantalum chloride powder. The temperature range for the third sintering of the first silicon-containing powder and the carbon powder under a nitrogen atmosphere is 1000℃~1800℃, and the time range for the third sintering of the first silicon-containing powder and the carbon powder under a nitrogen atmosphere is 1h~5h.

3. The method for preparing a composite coating for graphite components as described in claim 1, characterized in that, The main component of the nitrogen-silicon synthetic powder obtained is Si. x N y The particle size range of nitrogen-silicon synthetic powder with a certain particle size is 1μm~5μm.

4. The method for preparing a composite coating for graphite components as described in claim 1, characterized in that, The carbon-tantalum coating liquid comprises: a second silicon-containing powder, carbon powder, and a second tantalum-containing powder; the particle size range of the second silicon-containing powder, the carbon powder, and the second tantalum-containing powder is 1μm to 5μm; the second silicon-containing powder comprises one or two of SiO2 and Si, and the second tantalum-containing powder comprises one or more of tantalum powder, tantalum oxide powder, and tantalum chloride powder.

5. The method for preparing a composite coating for graphite components as described in claim 1, characterized in that, The first sintering temperature range is 1200℃~2000℃ and the first sintering time range is 1h~50h; the second sintering temperature range is 1600℃~2400℃ and the second sintering time range is 1h~50h.

6. The method for preparing a composite coating for graphite components as described in claim 1, characterized in that, The TaC coating has a certain porosity.

7. A graphite component with a composite coating, characterized in that, The invention includes a graphite component and a TaN coating and a TaC coating on the surface of the graphite component. The TaN coating is attached to the surface of a graphite substrate, and the TaC coating is attached to the surface of the TaN coating. The coefficient of thermal expansion of TaN is between that of the graphite substrate and the TaC. The TaN coating and the TaC coating are prepared by the method described in any one of claims 1 to 6.

8. A graphite component with a composite coating as described in claim 7, characterized in that, The thickness of the TaN coating ranges from 15 μm to 40 μm, and the thickness of the TaC coating ranges from 10 μm to 30 μm.

9. A graphite crucible for N-type crystal growth, characterized in that, The invention includes a graphite crucible and a TaN coating and a TaC coating located on the inner surface of the graphite crucible. The TaN coating is attached to the inner surface of the graphite crucible, and the TaC coating is attached to the surface of the TaN coating. The coefficient of thermal expansion of TaN is between that of the graphite substrate and the coefficient of thermal expansion of TaC. The TaN coating and the TaC coating are prepared by the method described in any one of claims 1 to 6.

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