A si c powder, a method of preparation and use thereof

Abstract

The application discloses a preparation method of SiC powder, and comprises the following steps: firstly, mixing silicon powder with a purity of 9N and carbon powder to obtain a precursor; and rapidly heating the sample by taking the Joule heat of the powder sample as a heat source to obtain high-purity SiC powder. The non-equilibrium reaction state generated by the ultrafast heating, cooling rate and short-time holding reduces the reaction energy barrier of the conversion of the silicon powder and the carbon powder into SiC, promotes the generation of high-value high-purity SiC products, and the products can be applied to various fields such as chip semiconductors, wear-resistant ceramics and new energy. The preparation method has the advantages that the SiC prepared by the rapid thermal shock technology has high purity and stable structure, the preparation method is simple, the material cost is greatly reduced, the SiC can be mass-produced, the production efficiency is improved, and the energy consumption is reduced.

Description

Technical Field

[0001] This invention belongs to the fields of chip semiconductor and chemical synthesis technology, specifically relating to a SiC powder, its preparation method, and its application. Background Technology

[0002] High-purity SiC powder is a core raw material for preparing third-generation semiconductor chip substrates. Its purity needs to reach 99.95%~99.9999%, and the content of impurity elements must be strictly controlled to meet the requirements of single crystal growth. As the basis of wide bandgap semiconductor materials, this powder directly affects the crystal quality and electrical performance of SiC wafers, and widely supports the manufacturing of devices in high-end fields such as aerospace and new energy vehicles.

[0003] Currently, mainstream preparation processes can be divided into three categories: gas-phase methods, which control gas source impurities through CVD or plasma technology, can produce ultrafine, high-purity powders, but have low synthesis rates and high equipment costs, making mass production difficult; liquid-phase methods, represented by the sol-gel method, achieve molecular-level uniform mixing through hydrolysis-polymerization reactions, resulting in excellent purity, but with complex processes and long post-processing cycles; and solid-phase methods, with the most widely used being the improved self-propagating high-temperature synthesis method, which is simple and less polluting, but requires a high-temperature environment of 1400℃~2000℃, and subsequent pulverization and purification still present energy consumption issues. The traditional Atchison process, while having low equipment investment, has high impurity content, requiring multiple acid washing steps for impurity removal, further increasing costs.

[0004] Existing processes share common bottlenecks: gas-phase and liquid-phase methods are limited by reaction mechanisms and equipment costs, resulting in energy consumption per unit output that is 2 to 3 times higher than that of solid-phase methods. Even with optimized solid-phase methods, the production of one ton of powder still requires nearly a thousand kilograms of standard coal after the addition of pulverization and purification steps, and it is difficult to achieve both high yield and high purity. This situation of "high cost and low efficiency" has become a key obstacle restricting the large-scale application of SiC chips. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a SiC powder, its preparation method, and its applications. This invention uses high-purity silicon powder and carbon powder as raw materials and innovatively proposes a carbothermal reduction method based on Joule heating and high-temperature thermal shock technology. This method achieves non-equilibrium heat treatment of silicon powder and carbon powder on an open heating substrate, directly converting them into high-value, high-purity SiC under the ultra-high temperature (>2000℃) and extremely short time (seconds) non-equilibrium state generated by Joule heating. This invention breaks through the thermodynamic equilibrium limitations of traditional closed systems. Utilizing the instantaneous ultra-high temperature generated by Joule heating, impurity atoms gain enormous kinetic energy and rapidly vaporize; simultaneously, the unique open structure constructs a low-resistance gas diffusion channel, allowing vaporized impurities and byproducts to overflow the reaction zone, completely avoiding the problems of impurity re-condensation, secondary deposition, and lattice solid solution caused by gas retention in traditional processes.

[0006] The preparation process proposed in this invention is simple, easy to operate, highly reproducible, produces high-purity products, and has high stability, which is conducive to large-scale production and has excellent application prospects.

[0007] Specifically, the objective of this invention is achieved through the following technical solutions: This invention provides a method for preparing ultra-high purity SiC powder. The method includes first mixing high-purity silicon powder and carbon powder to obtain a precursor, and then performing heat treatment by a high-temperature heat treatment method to obtain high-purity SiC powder.

[0008] As one embodiment of the present invention, the method specifically includes the following steps: S1. A precursor is obtained by mixing high-purity silicon powder and carbon powder; S2. Spread the uniformly mixed precursor powder evenly on the heating substrate, place it in an argon protective atmosphere, and apply electricity to the heating substrate to achieve thermal shock treatment of the powder to obtain the high-purity SiC material.

[0009] In one embodiment of the present invention, the molar amount of carbon powder in the precursor in step S1 is not less than that of silicon powder.

[0010] Preferably, the silicon powder and carbon powder used in the precursor in step S1 have a purity of 9N.

[0011] As one embodiment of the present invention, the heating substrate used in step S2 is an open graphite crucible.

[0012] In one embodiment of the present invention, in step S2, the mixed precursor is laid flat on the bottom of an open graphite crucible, and the upper layer is covered with carbon cloth and carbon felt.

[0013] In one embodiment of the present invention, the temperature in step S2 is 1600~2200℃, the holding time is 5~900s, and the thermal shock heating and cooling rate is 100℃ / s~1000℃ / s.

[0014] Preferably, the heating and cooling rate is 100℃ / s to 400℃ / s.

[0015] In some implementation examples, a method for preparing ultra-high purity SiC powder includes the following steps: (1) Weigh high-purity silicon powder and carbon powder, and grind them evenly using a ball mill or grinder; (2) The precursor is placed in an open graphite crucible, and the crucible is placed in a high-temperature thermal shock device under an argon atmosphere. It is then subjected to one-step heat treatment at different temperatures. After cooling, a high-purity SiC product with impurities removed is obtained.

[0016] The mechanism of this invention lies in mixing high-purity silicon powder and carbon powder, and using a non-equilibrium reaction system provided by Joule heating via high-temperature thermal shock technology, directly converting the silicon powder and carbon powder into high-value, high-purity SiC through a carbothermic reaction. The reaction process is as follows: Si + C = SiC This invention provides a method for preparing ultra-high purity SiC powder, using high-temperature thermal shock technology to produce high-value SiC products. Furthermore, the powder is abundant, inexpensive, and readily available, effectively reducing the production cost of high-purity SiC powder.

[0017] Compared with the prior art, the present invention has the following advantages: The method for preparing ultra-high purity SiC powder provided by this invention is highly efficient and practical, and can improve the purity of the product to above 6N with a yield of not less than 90%.

[0018] (2) The SiC prepared by this invention has high purity and uniform morphology, and can be used in semiconductor materials, new energy materials and wear-resistant ceramics and other fields.

[0019] (3) The preparation method proposed in this invention requires simple equipment, is easy to operate, has controllable conditions, high repeatability, and low preparation cost, making it suitable for large-scale factory production. Attached Figure Description

[0020] Figure 1 This is a graph showing the temperature variation during heat treatment using the high-temperature thermal shock technology employed in this invention. Figure 2 Transmission electron microscope (TEM) images and high-resolution TEM images of the high-purity SiC obtained by this invention. Figure 3 This is a distribution diagram of various elements in the high-purity SiC obtained by this invention; Figure 4 The XRD curve of the high-purity SiC obtained in this invention; Figure 5 SEM image of the high-purity SiC obtained in this invention; Figure 6 EDS image of high-purity SiC obtained in this invention; Figure 7 The Raman curve of the high-purity SiC obtained by this invention is shown. Detailed Implementation

[0021] The following examples are provided to further illustrate the present invention and are intended to explain the invention, not to limit its scope. Unless otherwise specified, all terms are parts by weight and weight percentages.

[0022] Unless otherwise specified, the raw materials used in this invention are all conventional commercially available products; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0023] The embodiments of the present invention will be further described below with reference to several examples.

[0024] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0025] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0026] Example 1 (1) Weigh high-purity silicon powder and carbon powder in a 1:1 molar ratio, and mix them evenly in a mortar to obtain the precursor; (2) Weigh 80 mg of the precursor and spread it evenly at the bottom of the cylindrical cavity of the special graphite crucible; (3) Cut carbon cloth and carbon felt of appropriate size, place one layer of carbon cloth and two layers of carbon felt on the top of the powder precursor in a special graphite crucible and press them tightly. (4) The sample was heat-treated using a high-temperature thermal shock device with a heating time of 20s, a heat treatment temperature of 2200℃, and a holding time of 300s. After cooling to room temperature, high-purity SiC was obtained with a yield of 92%.

[0027] Figure 1 The diagram shows the temperature change during the high-temperature thermal shock technology used in this invention. The heating time is 20s, the heat treatment temperature is 2200℃, and the holding time is 300s. Figure 2 The images shown are transmission electron microscope (TEM) images and high-resolution TEM images of the high-purity SiC obtained in this invention, indicating that the material consists of nanoparticles with a particle size of about 50 nm, and the interplanar spacing measurements confirm that it is 6H-SiC. Figure 3 The image shows the elemental distribution of the high-purity SiC obtained by this invention, proving that Si and C elements are uniformly distributed in the sample. Figure 4 The XRD curve of the high-purity SiC obtained in this invention proves that it is a 6H-SiC phase and there are no other impurity phases. Figure 5 The image shows a SEM image of the high-purity SiC obtained in this invention, indicating that the material is composed of nanoparticles. Figure 6 The image shows an EDS image of the high-purity SiC obtained in this invention, indicating that the material has high purity. Figure 7 The Raman curve of the high-purity SiC obtained in this invention confirms that it is a 6H-SiC phase; Glow discharge mass spectrometry tests showed that the material had a purity of 99.9999 at.

[0028] Example 2 (1) Weigh high-purity silicon powder and carbon powder in a 1:1 molar ratio, and mix them evenly in a mortar to obtain the precursor; (2) Weigh 80 mg of the precursor and spread it evenly at the bottom of the cylindrical cavity of the special graphite crucible; (3) Cut carbon cloth and carbon felt of appropriate size, place one layer of carbon cloth and two layers of carbon felt on the top of the powder precursor in a special graphite crucible and press them tightly. (4) The sample was heat-treated using a high-temperature thermal shock device with a heating time of 18s, a heat treatment temperature of 1800℃, and a holding time of 30s. After cooling to room temperature, high-purity 3C-SiC was obtained with a yield of 90%.

[0029] Characterization of its morphology and structure using scanning electron microscopy, transmission electron microscopy, and XRD revealed that high-purity SiC was successfully prepared. The high-purity SiC prepared in this example is composed of nanoparticles.

[0030] Example 3 (1) Weigh high-purity silicon powder and carbon powder in a 1:1 molar ratio, and mix them evenly in a mortar to obtain the precursor; (2) Weigh 80 mg of the precursor and spread it evenly at the bottom of the cylindrical cavity of the special graphite crucible; (3) Cut carbon cloth and carbon felt of appropriate size, place one layer of carbon cloth and two layers of carbon felt on the top of the powder precursor in a special graphite crucible and press them tightly. (4) The sample was heat-treated using a high-temperature thermal shock device with a heating time of 15s, a heat treatment temperature of 2000℃, and a holding time of 30s. After cooling to room temperature, high-purity SiC was obtained with a yield of 90%.

[0031] Characterization of its morphology and structure using scanning electron microscopy, transmission electron microscopy, and XRD revealed that high-purity 3C-SiC was successfully prepared. The high-purity SiC prepared in this example is composed of nanoparticles.

[0032] Example 4 (1) Weigh high-purity silicon powder and carbon powder in a 1:1 molar ratio, and mix them evenly in a mortar to obtain the precursor; (2) Weigh 80 mg of the precursor and spread it evenly at the bottom of the cylindrical cavity of the special graphite crucible; (3) Cut carbon cloth and carbon felt of appropriate size, place one layer of carbon cloth and two layers of carbon felt on the top of the powder precursor in a special graphite crucible and press them tightly. (4) The sample was heat-treated using a high-temperature thermal shock device with a heating time of 10s, a heat treatment temperature of 2200℃, and a holding time of 100s. After cooling to room temperature, high-purity 3C-SiC was obtained with a yield of 93%.

[0033] Characterization of its morphology and structure using scanning electron microscopy, transmission electron microscopy, and XRD revealed that high-purity SiC was successfully prepared. The high-purity SiC prepared in this example is composed of nanoparticles.

[0034] The above embodiments detail the structure, features, and effects of the present invention. The above descriptions are merely preferred embodiments of the present invention. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent variations, shall still fall within the scope of protection of the present invention if they do not exceed the scope covered by the specification.

Claims

1. A method for preparing SiC powder, characterized in that, Silicon powder and carbon powder are mixed to obtain a precursor, and the precursor is heated by Joule thermal shock to obtain SiC powder.

2. The method according to claim 1, characterized in that, The heating temperature is 1600~2200℃.

3. The method according to claim 1, characterized in that, The molar amount of the carbon powder is not less than that of the silicon powder.

4. The method according to claim 1, characterized in that, The precursor is placed on a heated substrate, covered with carbon cloth and carbon felt, and subjected to Joule thermal shock in an argon atmosphere.

5. The method according to claim 4, characterized in that, The heating substrate is an open graphite crucible.

6. The method according to claim 1, characterized in that, The purity of the silicon powder and carbon powder is 9N.

7. The method according to claim 1, characterized in that, The heating and cooling rates are 100℃ / s to 1000℃ / s.

8. A SiC powder prepared by the method described in claim 1.

9. The SiC powder according to claim 8, characterized in that, The purity is not less than 6N.

10. The application of the SiC powder as described in claim 8 in the preparation of semiconductor chips, wear-resistant ceramic materials, and new energy materials.

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