Thickness-controllable tantalum carbide coating for semiconductor crystal growth and preparation method thereof

Abstract

The invention discloses a thickness-controllable tantalum carbide coating for semiconductor crystal growth and a preparation method thereof, and the preparation method comprises the following steps: carrying out polishing treatment on the surface of graphite, then carrying out ultrasonic cleaning on the surface of the graphite, and then carrying out drying treatment on the graphite to obtain a clean graphite matrix; the preparation method comprises the following steps: uniformly mixing chloride, a tantalum precursor and a carbon source by adopting a ball milling process to prepare mixed powder; and putting the graphite matrix and the mixed powder into a corundum crucible, sintering for 2-10 hours at 1000-1500 DEG C in an argon atmosphere, and finally cleaning with boiling water to obtain the graphite with the tantalum carbide coating. According to the method, the chloride, the tantalum precursor and the carbon source are fully mixed by planetary ball milling, and the thickness-controllable growth of the coating can be realized by regulating and controlling the addition amount of the carbon source and the sintering time; the preparation method of the tantalum carbide coating has the advantages that the process is simple, the preparation period is short, the raw materials are easy to obtain, the required equipment investment is low, the reaction environment requirement is low, and the production cost is low.

Description

Technical Field

[0001] This invention relates to the field of tantalum carbide coating technology, and particularly to a tantalum carbide coating with controllable thickness for semiconductor crystal growth and its preparation method. Background Technology

[0002] In semiconductor crystal growth processes, graphite components (such as crucibles and crystal growth rings) within the crystal growth furnace are exposed to highly corrosive and reactive atmospheres for extended periods. This typically leads to shortened lifespan of the graphite components and decreased stability of the crystal growth process. While traditional graphite materials possess excellent high-temperature resistance and electrical conductivity, their corrosion resistance is insufficient, making them prone to interfacial reactions and the introduction of impurities. This negatively impacts crystal growth quality, resulting in defects such as edge polycrystalline structures, crystal depressions, and micropipes.

[0003] Currently, surface protection for graphite components primarily employs silicon carbide (SiC) or tantalum carbide (TaC) coatings. Compared to SiC coatings, TaC, among high-temperature ceramics, possesses higher melting and boiling points, exhibits structural stability in high-temperature oxygen-free or high-temperature low-pressure environments, and demonstrates excellent corrosion resistance and thermal shock resistance, making it an ideal coating material for growing wide-bandgap semiconductors. However, existing low-cost TaC coating preparation techniques suffer from uncontrollable coating thickness, making it difficult to meet the stringent requirements of semiconductor-grade crystal growth furnaces for coating uniformity and reliability. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a tantalum carbide coating with controllable thickness for semiconductor crystal growth and its preparation method.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A method for preparing a tantalum carbide coating with controllable thickness for semiconductor crystal growth, the method comprising the following steps:

[0007] S1: Polish the surface of the graphite, then ultrasonically clean the surface of the graphite, and then dry the graphite to obtain a clean graphite matrix.

[0008] S2: The chloride, tantalum precursor and carbon source are uniformly mixed by ball milling to prepare a mixed powder;

[0009] S3: The graphite matrix and the mixed powder are placed in a corundum crucible and sintered at 1000-1500℃ for 2-10 hours under an argon atmosphere (flow rate of 60-400 ml / min). Finally, graphite with a tantalum carbide coating is obtained by washing with boiling water.

[0010] S4: By controlling the mass ratio of the carbon source in the mixed powder and the sintering time of the graphite matrix and the mixed powder in the corundum crucible, tantalum carbide coatings of different thicknesses can be obtained.

[0011] The tantalum precursor includes any one or two of tantalum powder, potassium fluorotantalate, tantalum pentachloride, or tantalum pentoxide.

[0012] The carbon source includes any one of asphalt, carbon fiber powder, graphene, graphite nanosheets, petroleum coke, or needle coke.

[0013] Furthermore, the density of the graphite is 1.75–1.88 g / cm³. 3 The coefficient of thermal expansion of the graphite is 6.0 × 10⁻⁶. -6 ~6.4×10 -6 K -1 .

[0014] Furthermore, the graphite is first ultrasonically cleaned in deionized water, and then ultrasonically cleaned in anhydrous ethanol.

[0015] Furthermore, the graphite is dried at a temperature of 60–100°C for a time of 7–15 hours.

[0016] Furthermore, the chloride is any two of calcium chloride, magnesium chloride, zinc chloride, sodium chloride, potassium chloride, and lithium chloride.

[0017] Furthermore, the purity of the chloride is greater than 99.5%, the purity of the tantalum precursor is greater than 99%, and the purity of the carbon source is greater than 99.5%.

[0018] Furthermore, in the ball milling process, the mass ratio of the chloride, the tantalum precursor, and the carbon source is 1–50:1–50:1–50, the ball milling speed is 300–800 r / min, the ball milling time is 2–10 h, and the mass ratio of balls to material is 5:1.

[0019] Furthermore, the heating rate in the corundum crucible is 5-10 °C / min, and the crucible is cooled to room temperature after sintering.

[0020] Furthermore, the boiling water cleaning is performed in boiling deionized water, and the cleaning is repeated 5 to 10 times to completely remove impurities from the tantalum carbide coating.

[0021] A method for preparing a tantalum carbide coating with controllable thickness for semiconductor crystal growth, wherein the tantalum carbide coating obtained by the method is described.

[0022] The beneficial effects of this invention are:

[0023] This invention utilizes a molten salt method to prepare graphite-based tantalum carbide coatings with controllable thickness. The method employs a planetary ball mill to thoroughly mix chloride, tantalum precursor, and carbon source. By controlling the amount of carbon source added and the sintering time, controllable growth of the coating thickness can be achieved. This tantalum carbide coating preparation method has advantages such as simple process, short preparation cycle, readily available raw materials, low equipment investment, low environmental requirements for the reaction, and low production cost. Furthermore, the prepared tantalum carbide coating exhibits uniform elemental distribution, a single phase, and controllable thickness. Attached Figure Description

[0024] Figure 1 The image shows a scanning electron microscope (SEM) image and the corresponding elemental distribution diagram of the tantalum carbide coating prepared on the graphite substrate in Example 1 (red dots represent carbon elements, and green parts represent tantalum elements).

[0025] Figure 2 The image shows the X-ray diffraction (XRD) pattern of the tantalum carbide coating prepared on the graphite substrate in Example 1.

[0026] Figure 3 The images show XRD comparisons of tantalum carbide coatings prepared on graphite substrates in Examples 1, 2, 3, 4 and Comparative Example 1. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] See Figures 1-3 The present invention provides a technical solution:

[0029] A method for preparing a tantalum carbide coating with controllable thickness for semiconductor crystal growth, comprising the following steps:

[0030] (1) The surface of the graphite is polished, then ultrasonically cleaned, and finally dried to obtain a clean graphite matrix. The density of the graphite is 1.75–1.88 g / cm³. 3 The coefficient of thermal expansion of graphite is 6.0 × 10⁻⁶. -6 ~6.4×10 -6 K -1 Graphite is first ultrasonically cleaned in deionized water, and then ultrasonically cleaned in anhydrous ethanol. The drying temperature of graphite is 60–100℃, and the drying time is 7–15 hours.

[0031] (2) A mixed powder is prepared by uniformly mixing chloride, tantalum precursor, and carbon source using a ball milling process. The chloride is any two of calcium chloride, magnesium chloride, zinc chloride, sodium chloride, potassium chloride, and lithium chloride. The purity of the chloride is greater than 99.5%, the purity of the tantalum precursor is greater than 99%, and the purity of the carbon source is greater than 99.5%. In the ball milling process, the mass ratio of chloride, tantalum precursor, and carbon source is 1–50:1–50:1–50, the ball milling speed is 300–800 r / min, the ball milling time is 2–10 h, and the mass ratio of balls to material is 5:1. The tantalum precursor includes any one or two of tantalum powder, potassium fluorotantalate, tantalum pentachloride, or tantalum pentoxide; the carbon source includes any one of pitch, carbon fiber powder, graphene, graphite nanosheets, petroleum coke, or needle coke.

[0032] (3) The graphite matrix and the mixed powder were placed in an alumina crucible and sintered at 1000–1500 °C for 2–10 h under an argon atmosphere (flow rate of 60–400 ml / min). Finally, the graphite with a tantalum carbide coating was obtained by boiling water washing. The heating rate in the alumina crucible was 5–10 °C / min. After sintering, the mixture was cooled to room temperature. Boiling water washing was performed in boiling deionized water, and the washing was performed 5–10 times to completely remove impurities from the tantalum carbide coating.

[0033] (4) By controlling the mass ratio of carbon source in the mixed powder and the sintering time of graphite matrix and mixed powder in the corundum crucible, tantalum carbide coatings of different thicknesses can be obtained.

[0034] A tantalum carbide coating with controllable thickness is a tantalum carbide coating obtained by the above preparation method.

[0035] Example 1

[0036] This embodiment provides a method for preparing a tantalum carbide coating with controllable thickness for semiconductor crystal growth, including the following steps:

[0037] (1) For materials with a density of 1.75~1.88g / cm3 and a coefficient of thermal expansion of 6.0×10 -6 ~6.4×10 -6 The graphite matrix of K-1 was polished to obtain a smooth surface, and then ultrasonically cleaned with deionized water and anhydrous ethanol in sequence. After drying at 80°C for 7 hours, a clean graphite matrix was obtained for later use.

[0038] (2) Calcium chloride, potassium chloride, potassium fluorotantalate, tantalum pentoxide, and asphalt were mixed using a ball milling method. The mass ratio of calcium chloride, potassium chloride, potassium fluorotantalate, and tantalum pentoxide was 11:33:9:1, and the mass ratio of potassium fluorotantalate, tantalum pentoxide, and asphalt was 9:1:20. The ball milling speed was 450 r / min, the milling time was 5 h, and the mass ratio of balls to material was 5:1, resulting in a mixed powder.

[0039] (3) The dried graphite and mixed powder were placed in an alumina crucible and sintered at 1150℃ for 4 hours, with a heating rate of 5℃ / min and an Ar atmosphere. After sintering, the samples were cooled to room temperature in the furnace. The sintered samples were washed 10 times with boiling water to obtain a graphite-based tantalum carbide coating.

[0040] The scanning electron microscope and elemental distribution map of the sample coating section obtained after step (3) are shown below. Figure 1 As shown, the Ta and C elements in the coating are uniformly distributed, and its thickness is 23.7 μm. The corresponding XRD pattern of the sample is shown below. Figure 2 As shown, the coating contains only the TaC phase and has a high degree of crystallinity.

[0041] Example 2

[0042] This embodiment provides a method for preparing a tantalum carbide coating with controllable thickness for semiconductor crystal growth, including the following steps:

[0043] (1) For materials with a density of 1.75~1.88g / cm3 and a coefficient of thermal expansion of 6.0×10 -6 ~6.4×10 -6 The graphite matrix of K-1 was polished to obtain a smooth surface, and then ultrasonically cleaned with deionized water and anhydrous ethanol in sequence. After drying at 80°C for 7 hours, a clean graphite matrix was obtained for later use.

[0044] (2) Calcium chloride, potassium chloride, potassium fluorotantalate, tantalum pentoxide, and asphalt were mixed using a ball milling method. The mass ratio of calcium chloride, potassium chloride, potassium fluorotantalate, and tantalum pentoxide was 11:33:9:1, and the mass ratio of potassium fluorotantalate, tantalum pentoxide, and asphalt was 9:1:10. The ball milling speed was 450 r / min, the milling time was 5 h, and the mass ratio of balls to materials was 5:1, resulting in a mixed powder.

[0045] (3) The dried graphite and mixed powder were placed in an alumina crucible and sintered at 1150℃ for 3 hours, with a heating rate of 5℃ / min and an Ar atmosphere. After sintering, the samples were cooled to room temperature in the furnace. The sintered samples were washed 10 times with boiling water to obtain a graphite-based tantalum carbide coating.

[0046] The XRD pattern of the sample obtained after step (3) is shown below. Figure 3As shown, the coating contains only a single TaC phase.

[0047] Example 3

[0048] This embodiment provides a method for preparing a tantalum carbide coating with controllable thickness for semiconductor crystal growth, including the following steps:

[0049] (1) For materials with a density of 1.75~1.88g / cm3 and a coefficient of thermal expansion of 6.0×10 -6 ~6.4×10 -6 The graphite matrix of K-1 was polished to obtain a smooth surface, and then ultrasonically cleaned with deionized water and anhydrous ethanol in sequence. After drying at 80°C for 7 hours, a clean graphite matrix was obtained for later use.

[0050] (2) Calcium chloride, potassium chloride, potassium fluorotantalate, tantalum pentoxide, and asphalt were mixed using a ball milling method. The mass ratio of calcium chloride, potassium chloride, potassium fluorotantalate, and tantalum pentoxide was 11:33:9:1, and the mass ratio of potassium fluorotantalate, tantalum pentoxide, and asphalt was 9:1:5. The ball milling speed was 450 r / min, the milling time was 5 h, and the mass ratio of balls to material was 5:1, resulting in a mixed powder.

[0051] (3) The dried graphite and the ball-milled mixed powder were placed in an alumina crucible and sintered at 1150℃ for 3 hours, with a heating rate of 5℃ / min and an Ar atmosphere. After sintering, the sample was cooled to room temperature in the furnace. The sintered sample was washed 10 times with boiling water to obtain a graphite-based tantalum carbide coating.

[0052] The XRD pattern of the sample obtained after step (3) is shown below. Figure 3 As shown, the coating contains only a single TaC phase.

[0053] Example 4

[0054] This embodiment provides a method for preparing a tantalum carbide coating with controllable thickness for semiconductor crystal growth, including the following steps:

[0055] (1) For materials with a density of 1.75~1.88g / cm3 and a coefficient of thermal expansion of 6.0×10 -6 ~6.4×10 -6 The graphite matrix of K-1 was polished to obtain a smooth surface, and then ultrasonically cleaned with deionized water and anhydrous ethanol in sequence. After drying at 80°C for 7 hours, a clean graphite matrix was obtained for later use.

[0056] (2) Calcium chloride, potassium chloride, potassium fluorotantalate, tantalum pentoxide, and carbon fiber were mixed using ball milling. The mass ratio of calcium chloride, potassium chloride, potassium fluorotantalate, and tantalum pentoxide was 11:33:9:1, and the mass ratio of potassium fluorotantalate, tantalum pentoxide, and carbon fiber powder was 9:1:15. The ball milling speed was 450 r / min, the milling time was 5 h, and the mass ratio of balls to materials was 5:1 to obtain a mixed powder.

[0057] (3) The dried graphite and the ball-milled mixed powder were placed in an alumina crucible and sintered at 1150℃ for 3 hours, with a heating rate of 5℃ / min and an Ar atmosphere. After sintering, the sample was cooled to room temperature in the furnace. The sintered sample was washed 10 times with boiling water to obtain a graphite-based tantalum carbide coating.

[0058] The XRD pattern of the sample obtained after step (3) is shown below. Figure 3 As shown, the coating contains only a single TaC phase.

[0059] Comparative Example 1

[0060] This comparative example is basically the same as Example 1, except that no asphalt is added in step (2) of this comparative example, and the other steps are performed sequentially. The XRD pattern of the obtained sample coating is shown in the figure. Figure 3 As shown.

[0061] Comparative Example 2

[0062] This comparative example is basically the same as Example 1, except that the sintering time in step (3) of this comparative example is 6 hours, and the other steps are performed sequentially. The XRD pattern of the obtained sample coating is shown below. Figure 3 As shown.

[0063] The thicknesses of the graphite-based tantalum carbide coatings obtained through the above embodiments and comparative examples are shown in Table 1.

[0064] Table 1 Comparison of the thickness of graphite-based tantalum carbide coatings obtained in the examples and comparative examples.

[0065]

[0066] As shown in Table 1, the introduction of a carbon source can significantly increase the coating thickness, indicating that it promotes coating growth during sintering. Furthermore, as shown in Examples 1, 2, 3 and Comparative Example 1, the carbon source content and sintering time also have a certain impact on the coating thickness. This means that by adjusting these two key parameters—carbon source content and sintering time—effective control of the tantalum carbide coating thickness can be achieved.

[0067] The morphology and phase characterization results of the graphite-based tantalum carbide coatings obtained through the above embodiments and comparative examples are as follows: Figure 1 , Figure 2and Figure 3 As shown, Figure 1 The image shows a scanning electron microscope (SEM) image and elemental distribution diagram of the cross-section of the graphite-based tantalum carbide coating in Example 1. Figure 2 The image shows the XRD pattern of the graphite-based tantalum carbide coating in Example 1. Figure 3 The images show the XRD patterns of the graphite-based tantalum carbide coatings in Examples 1, 2, 3, 4 and Comparative Examples 1 and 2.

[0068] Depend on Figure 1 It is evident that the preparation method of the present invention can successfully prepare tantalum carbide coatings with the following characteristics: (1) the coating can completely cover the surface of the graphite substrate; (2) the tantalum element is uniformly distributed in the coating. This result indicates that the method has good surface coverage and elemental dispersion during the coating preparation process.

[0069] Phase analysis of the prepared graphite-based tantalum carbide coating was performed using XRD. Figure 2 As shown, the XRD pattern of the obtained coating only shows typical TaC diffraction peaks, and no diffraction signals of Ta2C, free carbon or other impurity phases were detected, indicating that the method successfully prepared a high-purity tantalum carbide coating with good crystallinity and a single phase.

[0070] Further comparison of the XRD patterns of samples under different process parameters ( Figure 3 The study included Examples 1-3 (different carbon source contents), Example 4 (different carbon sources), and Comparative Examples 1 (traditional molten salt method) and 2 (different sintering times). The XRD patterns of all samples showed completely consistent TaC characteristic peaks, confirming that the method can guarantee the phase purity of the product. Particularly noteworthy is that even with an extended sintering time of 6 hours (Comparative Example 2), no transformation of TaC to other phases was observed, indicating that the method possesses excellent phase stability.

[0071] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A method for preparing a tantalum carbide coating with controllable thickness for semiconductor crystal growth, characterized in that, The preparation method includes the following steps: S1: Polish the surface of the graphite, then ultrasonically clean the surface of the graphite, and then dry the graphite to obtain a clean graphite matrix. S2: The chloride, tantalum precursor and carbon source are uniformly mixed by ball milling to prepare a mixed powder; S3: The graphite matrix and the mixed powder are placed in a corundum crucible and sintered at 1000-1500℃ for 2-10 hours under an argon atmosphere. Finally, graphite with a tantalum carbide coating is obtained by washing with boiling water. S4: By controlling the mass ratio of the carbon source in the mixed powder and the sintering time of the graphite matrix and the mixed powder in the corundum crucible, tantalum carbide coatings of different thicknesses can be obtained. The tantalum precursor includes any one or two of tantalum powder, potassium fluorotantalate, tantalum pentachloride, or tantalum pentoxide. The carbon source includes any one of asphalt, carbon fiber powder, graphene, graphite nanosheets, petroleum coke, or needle coke.

2. The preparation method according to claim 1, characterized in that: The density of the graphite is 1.75–1.88 g / cm³. 3 The coefficient of thermal expansion of the graphite is 6.0 × 10⁻⁶. -6 ~6.4×10 -6 K -1 .

3. The preparation method according to claim 1, characterized in that: The graphite was first ultrasonically cleaned in deionized water, and then ultrasonically cleaned in anhydrous ethanol.

4. The preparation method according to claim 1, characterized in that: The graphite is dried at a temperature of 60–100°C for 7–15 hours.

5. The preparation method according to claim 1, characterized in that: The chloride is any two of calcium chloride, magnesium chloride, zinc chloride, sodium chloride, potassium chloride, and lithium chloride.

6. The preparation method according to claim 1, characterized in that: The purity of the chloride is greater than 99.5%, the purity of the tantalum precursor is greater than 99%, and the purity of the carbon source is greater than 99.5%.

7. The preparation method according to claim 1, characterized in that: In the ball milling process, the mass ratio of the chloride, the tantalum precursor, and the carbon source is 1-50:1-50:1-50, the ball milling speed is 300-800 r / min, the ball milling time is 2-10 h, and the mass ratio of balls to material is 5:

1.

8. The preparation method according to claim 1, characterized in that: The heating rate in the corundum crucible is 5-10 °C / min, and it is cooled to room temperature after sintering.

9. The preparation method according to claim 1, characterized in that: The boiling water cleaning is performed in boiling deionized water, and the cleaning is repeated 5 to 10 times to completely remove impurities from the tantalum carbide coating.

10. A tantalum carbide coating with controllable thickness for semiconductor crystal growth, characterized in that: The tantalum carbide coating obtained by the preparation method as described in any one of claims 1-9.

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