A high-quality silicon carbide powder and its preparation method and application

Abstract

The present invention relates to the field of inorganic non-metallic materials, and specifically discloses a high-quality silicon carbide powder, a preparation method and an application thereof. The present invention uses carbon powder and silicon powder as main raw materials, and uses silicon carbide powder of a specific particle size as an additive, and sintering at high temperature to prepare a high-quality silicon carbide powder with high loose density, good crystallization quality and high yield. The growth density of carbon inclusion defects in the silicon carbide single crystal prepared using the silicon carbide powder is low and the quality is high. The method for high-quality silicon carbide powder provided by the present invention is simple, and the raw materials are easily available, which effectively solves the problem in the prior art that the silicon carbide powder required for the growth of silicon carbide single crystals is limited in size and uneven in particle size, which leads to the easy occurrence of carbon inclusion defects in silicon carbide single crystals.

Description

Technical Field

[0001] The invention relates to the field of inorganic non-metallic materials, and specifically discloses high-quality silicon carbide powder, a preparation method and application thereof. Background Art

[0002] With the large-scale application of silicon carbide substrates in electronic devices, the demand for high-quality and large-sized silicon carbide crystals is becoming more and more urgent. However, the yield rate of silicon carbide single crystals grown by physical vapor transport method is low, and carbon inclusion defects are inevitable in silicon carbide single crystals. This is because during the single crystal growth process, the silicon carbide raw material sublimates into a silicon-rich vapor growth component, and the raw material gradually undergoes graphitization, producing a large number of fine carbon particles. The carbon particles with smaller particle sizes are carried to the growth interface under the action of the growth component of the raw material transported to the seed crystal, and then are wrapped by the subsequently grown single crystal, forming carbon particle carbon inclusion defects. Carbon particle inclusions can cause the proliferation of microtubes and penetrating dislocations, seriously affecting the quality of silicon carbide single crystals.

[0003] The particle size of silicon carbide raw materials has an important influence on the growth of silicon carbide crystals by physical vapor transport. The raw material particle size has a great influence on the sublimation rate of the raw material, the carbon-silicon ratio of the sublimated gas phase components and the heat transfer performance of the raw material, which in turn has a great influence on the stability of the grown single crystal and the growth efficiency. Based on this, large-particle silicon carbide raw materials with high bulk density and uniform and controllable particle size are very important for the growth of silicon carbide crystals. The particle size of the current mainstream silicon carbide raw materials is mostly on the order of tens of microns, but its size is not large enough and the particle size is not uniform enough, which easily causes the production of carbon inclusion defects. Therefore, designing a high-quality silicon carbide raw material with uniform particle size and suitable size has become a problem that needs to be solved in this field. Summary of the invention

[0004] In view of the problem in the prior art that the silicon carbide powder required for the growth of silicon carbide single crystals is limited in size and uneven in particle size, which leads to the problem that carbon inclusion defects are easily present in silicon carbide single crystals, the present invention provides a method for preparing high-quality silicon carbide powder. The present invention adds silicon carbide of a certain particle size as an additive on the basis of carbon powder and silicon powder as the main raw materials, and successfully prepares high-quality silicon carbide powder with high bulk density and good crystallization quality. The silicon carbide powder prepared by the present invention has a large size, uniform particle size, and a large weight, and is not easily brought to the growth interface of the silicon carbide crystal, thereby reducing the growth density of carbon inclusion defects and greatly improving the quality of the silicon carbide single crystal.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions.

[0006] The first aspect of the present invention provides a method for preparing high-quality silicon carbide powder, comprising the following steps: uniformly mixing carbon powder, silicon powder and additives, heating to 2050°C-2400°C for sintering in an inert atmosphere, cooling, and crushing to obtain the high-quality silicon carbide powder.

[0007] Wherein, the additive is silicon carbide powder with a particle size of 100 μm-400 μm.

[0008] Compared with the prior art, the present invention provides a simple method for preparing high-quality silicon carbide powder. The present invention uses carbon powder and silicon powder as the main raw materials, adds silicon carbide of a certain particle size as an additive, and successfully prepares a high-quality silicon carbide powder with high loose density, good crystal quality and a certain self-weight. Since the raw material size of silicon carbide prepared by the present invention is quite large and its particle size is uniform and controllable, it is not easy to be brought to the growth interface of silicon carbide single crystal after the single crystal raw material is graphitized, thereby reducing the density of carbon inclusion defects in the crystal and improving the quality of silicon carbide single crystal. Moreover, the silicon carbide powder prepared by the present application is conducive to the uniform sublimation of carbon components and silicon components during the growth of silicon carbide single crystals, so that they are uniformly deposited on the seed crystal, which is beneficial to the crystal stability of silicon carbide single crystals and effectively solves the problem of uneven raw material growth of large-diameter silicon carbide single crystals. The present invention can reduce the density of carbon inclusion defects in silicon carbide single crystals through simple raw materials and a simple synthesis process, thereby achieving a good effect of stabilizing the crystal form of silicon carbide single crystals, and has low cost and outstanding prospects for large-scale application. It effectively solves the problem in the prior art that the silicon carbide powder required for the growth of silicon carbide single crystals is limited in size and uneven in particle size, thereby causing carbon inclusion defects in silicon carbide single crystals to easily appear.

[0009] Preferably, the carbon powder is spherical high-purity carbon powder with a particle size of 20 μm-1.5 mm, and its purity is ≥99.999%.

[0010] Preferably, the silicon powder is high-purity silicon powder with a particle size of 0.01 mm-25 mm and a purity of ≥99.999%.

[0011] Preferably, the silicon carbide powder has a spherical shape and a purity of ≥99.9993%.

[0012] Preferably, the mass ratio of the carbon powder to the silicon powder is 10-14:26-30.

[0013] Preferably, the mass ratio of the amount of the additive added to the total mass of the carbon powder and the silicon powder is 0.05-0.3:1.

[0014] Preferably, the sintering time is 1.5h-5h.

[0015] Preferably, the temperature is increased by programmed temperature increase at a rate of 5°C / min-20°C / min.

[0016] Preferably, the temperature is lowered to room temperature by programmed cooling, and the cooling rate is 10°C / min-30°C / min.

[0017] A second aspect of the present invention provides a high-quality silicon carbide powder, which is prepared using the method for preparing the high-quality silicon carbide powder.

[0018] Preferably, the particle size of the high-quality silicon carbide powder is 5 mm-10 mm.

[0019] Preferably, the bulk density of the high-quality silicon carbide powder is 1.2 g / cm 3 -1.8g / cm 3 .

[0020] A third aspect of the present invention provides an application of the high-quality silicon carbide powder in the growth of silicon carbide single crystals.

[0021] In summary, the present invention provides a high-quality silicon carbide powder, a preparation method thereof, and an application thereof in the growth of silicon carbide single crystals. The present invention uses carbon powder and silicon powder as main raw materials, and silicon carbide powder of a specific particle size as an additive, and sintering at high temperature to prepare a high-quality silicon carbide powder with high loose density and good crystallization quality. The silicon carbide single crystal prepared using the silicon carbide powder has a low growth density of carbon inclusion defects and high quality. The method for the high-quality silicon carbide powder provided by the present invention is simple, and the raw materials are readily available, which effectively solves the problem in the prior art that the silicon carbide powder required for the growth of silicon carbide single crystals is limited in size and uneven in particle size, which results in the carbon inclusion defects in the silicon carbide single crystals being prone to occur. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a photo of a silicon carbide single crystal ingot prepared using the high-quality silicon carbide powder obtained in Example 1;

[0023] Figure 2 This is a photo of a silicon carbide single crystal ingot prepared using the high-quality silicon carbide powder obtained in Example 2;

[0024] Figure 3 This is a photo of a silicon carbide single crystal ingot prepared using the high-quality silicon carbide powder obtained in Example 3;

[0025] Figure 4 This is a photo of a silicon carbide single crystal ingot prepared using the high-quality silicon carbide powder obtained in Example 4;

[0026] Figure 5This is a photo of a silicon carbide single crystal ingot prepared using the high-quality silicon carbide powder obtained in Example 5;

[0027] Figure 6 This is a photo of a silicon carbide single crystal ingot prepared using the silicon carbide powder obtained in Comparative Example 1;

[0028] Figure 7 This is a photograph of a silicon carbide single crystal ingot prepared using the silicon carbide powder obtained in Comparative Example 3. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Example 1

[0031] This embodiment provides a high-quality silicon carbide powder, which specifically includes the following steps:

[0032] Weigh 3kg of spherical high-purity carbon powder with a purity of 99.999% and a particle size of 50μm-150μm, 7kg of high-purity silicon powder with a purity of 99.999% and a particle size of 0.12mm, and 1.8kg of spherical silicon carbide powder with a purity of 99.9995% and a particle size of 250μm-400μm, mix them evenly, put them into a graphite crucible, transfer the graphite crucible to a high-temperature synthesis furnace, and heat them to 2250℃ at a heating rate of 10℃ / min under an inert atmosphere. Sinter for 3h, cool them to room temperature at a cooling rate of 25℃ / min after sintering, and crush them to obtain high-quality silicon carbide powder with a particle size of 5mm-10mm for the growth of the silicon carbide single crystal.

[0033] After testing, the obtained silicon carbide powder has no excess carbon powder inclusions and its bulk density is 1.7g / cm 3 , the yield of silicon carbide powder is 96%.

[0034] Example 2

[0035] This embodiment provides a high-quality silicon carbide powder, which specifically includes the following steps:

[0036] Weigh 3.2 kg of spherical high-purity carbon powder with a purity of 99.999% and a particle size of 150 μm-250 μm, 6.8 kg of high-purity silicon powder with a purity of 99.999% and a particle size of 0.12 mm, and 1.8 kg of spherical silicon carbide powder with a purity of 99.9993% and a particle size of 150 μm-300 mm, mix them evenly, put them into a graphite crucible, transfer the graphite crucible to a high-temperature synthesis furnace, and heat them to 2200°C at a heating rate of 15°C / min under an inert atmosphere, sinter for 5 hours, cool them to room temperature at a cooling rate of 20°C / min after sintering, and crush them to obtain high-quality silicon carbide powder with a particle size of 5 mm-10 mm for the growth of the silicon carbide single crystal.

[0037] After testing, the obtained silicon carbide powder has no excess carbon powder inclusions and its bulk density is 1.2g / cm 3 The yield of silicon carbide powder is 85%.

[0038] Example 3

[0039] This embodiment provides a high-quality silicon carbide powder, which specifically includes the following steps:

[0040] Weigh 3kg of spherical high-purity carbon powder with a purity of 99.999% and a particle size of 50μm, 7kg of high-purity silicon powder with a purity of 99.999% and a particle size of 0.12mm, and 1.8kg of spherical silicon carbide powder with a purity of 99.9995% and a particle size of 15μm, mix them evenly, put them into a graphite crucible, transfer the graphite crucible to a high-temperature synthesis furnace, and heat them to 2050℃ at a heating rate of 5℃ / min under an inert atmosphere, sinter for 2h, and after sintering, cool them to room temperature at a cooling rate of 10℃ / min, crush them, and obtain high-quality silicon carbide powder with a particle size of 5mm-10mm for the growth of the silicon carbide single crystal.

[0041] After testing, the obtained silicon carbide powder has no excess carbon powder inclusions and its bulk density is 1.5g / cm 3 The yield of silicon carbide powder was 52%.

[0042] Example 4

[0043] This embodiment provides a high-quality silicon carbide powder, which specifically includes the following steps:

[0044] Weigh 3kg of spherical high-purity carbon powder with a purity of 99.999% and a particle size of 50μm, 7kg of high-purity silicon powder with a purity of 99.999% and a particle size of 0.12mm, and 1.8kg of spherical silicon carbide powder with a purity of 99.9995% and a particle size of 15μm, mix them evenly, put them into a graphite crucible, transfer the graphite crucible to a high-temperature synthesis furnace, and heat them to 2150℃ at a heating rate of 15℃ / min under an inert atmosphere. Sinter for 4h, cool them to room temperature at a cooling rate of 15℃ / min after sintering, and crush them to obtain high-quality silicon carbide powder with a particle size of 5mm-10mm for the growth of the silicon carbide single crystal.

[0045] After testing, the obtained silicon carbide powder is prone to contain excess carbon powder, and its bulk density is 1.8g / cm 3 The yield of silicon carbide powder is only 65%.

[0046] Example 5

[0047] This embodiment provides a high-quality silicon carbide powder, which specifically includes the following steps:

[0048] Weigh 3kg of spherical high-purity carbon powder with a purity of 99.999% and a particle size of 10μm, 7kg of high-purity silicon powder with a purity of 99.999% and a particle size of 0.12mm, and 1.8kg of spherical silicon carbide powder with a purity of 99.9995% and a particle size of 15μm, mix them evenly, put them into a graphite crucible, transfer the graphite crucible to a high-temperature synthesis furnace, and heat them to 2400℃ at a heating rate of 20℃ / min under an inert atmosphere. Sinter them for 1.5h, cool them to room temperature at a cooling rate of 15℃ / min after sintering, and crush them to obtain high-quality silicon carbide powder with a particle size of 5mm-10mm for the growth of the silicon carbide single crystal.

[0049] After testing, the obtained silicon carbide powder has no excess carbon powder inclusions and its bulk density is 1.1g / cm 3 The yield of silicon carbide powder was 55%.

[0050] Comparative Example 1

[0051] This comparative example provides a silicon carbide powder, which is different from Example 1 in that silicon carbide is not added as an additive, and other raw materials, amounts and preparation methods remain unchanged, and specifically comprises the following steps:

[0052] Weigh 3 kg of spherical high-purity carbon powder with a purity of 99.999% and a particle size of 50 μm and 7 kg of high-purity silicon powder with a purity of 99.999% and a particle size of 0.12 mm, mix them evenly, put them into a graphite crucible, transfer the graphite crucible to a high-temperature synthesis furnace, and heat them to 2250°C at a heating rate of 10°C / min under an inert atmosphere. Sinter for 3 hours, and after sintering, cool them to room temperature at a cooling rate of 25°C / min. No crushing is required to obtain high-quality silicon carbide powder with a particle size of 10 μm to 2 mm for the growth of the silicon carbide single crystal.

[0053] The obtained silicon carbide powder was tested to have excess carbon powder inclusions, and its bulk density was 0.8g / cm 3 .

[0054] Comparative Example 2

[0055] This comparative example provides commercially available silicon carbide powder, the purity of which is greater than 99.999%, more than 95% of which is in the form of α-silicon carbide and has a particle size of 0.1-2 mm.

[0056] In order to further demonstrate the technical effect of the present invention, the present invention uses the high-quality silicon carbide powder obtained in Example 1 and Example 5 and the silicon carbide powder obtained in Comparative Examples 1-2 to prepare silicon carbide single crystals, and the specific steps are shown in the test examples.

[0057] Test example

[0058] The obtained silicon carbide powder and seed crystal are loaded into a high-purity graphite crucible, the high-purity graphite crucible is transferred to a single crystal growth chamber and the growth chamber is sealed, a protective gas is introduced into the growth chamber, and a 6-inch 4H silicon carbide single crystal with no polymorphism, no visual inclusion aggregation area, and no microtube growth is grown using a traditional PVT method. The growth is repeated for 10 batches.

[0059] The present invention has carried out relevant performance tests on each silicon carbide single crystal obtained in the test example, and the results are shown in Table 1 and Figure 1-3 shown.

[0060] Table 1 Performance test results of various silicon carbide single crystals

[0061]

[0062] According to Table 1 and Figure 1-3 It can be seen that the growth rate of silicon carbide single crystals grown using the high-quality silicon carbide powder obtained in Example 1 is fast, the growth thickness is large, and the process yield is as high as 95%. Visually, the obtained silicon carbide single crystal ingot has no polymorphism, no micropipes, and no proliferation of defects in the area of ​​aggregation of inclusions.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing high-quality silicon carbide powder, characterized in that: The method comprises the following steps: uniformly mixing carbon powder, silicon powder and additives, heating to 2050°C-2400°C in an inert atmosphere for sintering, cooling, and crushing to obtain the high-quality silicon carbide powder; Wherein, the additive is silicon carbide powder with a particle size of 100 μm-400 μm; The mass ratio of the carbon powder to the silicon powder is 10-14:26-30; The sintering time is 1.5h-5h; The temperature is raised by programmed heating, and the heating rate is 5°C / min-20°C / min; The temperature is lowered to room temperature by programmed cooling, and the cooling rate is 10°C / min-30°C / min; The silicon carbide powder has a spherical shape and a purity of ≥99.9993%; The particle size of the high-quality silicon carbide powder is 5mm-10mm; The bulk density of the high-quality silicon carbide powder is 1.2 g / cm 3 -1.8g / cm 3 .

2. The method for preparing high-quality silicon carbide powder according to claim 1, characterized in that: The carbon powder is spherical high-purity carbon powder with a particle size of 20 μm-1.5 mm, and its purity is ≥99.999%.

3. The method for preparing high-quality silicon carbide powder according to claim 1, characterized in that: The silicon powder is high-purity silicon powder with a particle size of 0.01mm-25mm and a purity of ≥99.999%.

4. The method for preparing high-quality silicon carbide powder according to claim 1, characterized in that: The mass ratio of the additive amount to the total mass of the carbon powder and the silicon powder is 0.05-0.3:

1.

5. A high-quality silicon carbide powder, characterized by: The high-quality silicon carbide powder is prepared by the preparation method of any one of claims 1 to 4.

6. The high-quality silicon carbide powder according to claim 5, characterized in that: The particle size of the high-quality silicon carbide powder is 5mm-10mm; and / or The bulk density of the high-quality silicon carbide powder is 1.2 g / cm 3 -1.8g / cm 3 .

7. Use of the high-quality silicon carbide powder according to any one of claims 5 or 6 in the growth of silicon carbide single crystals.

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