Silicon carbide coating graphite base as well as preparation method and application thereof

Abstract

The invention relates to a silicon carbide coating graphite base and a preparation method and application thereof.The preparation method of the silicon carbide coating graphite base comprises the following steps that silicon-containing powder and a graphite base are placed in a reaction container, and the silicon-containing powder is selected from one of SiO powder or Si powder; the reaction container is vacuumized, CO gas is introduced into the reaction container and heated, the CO gas and silicon-containing gas formed by volatilization of the silicon-containing powder are subjected to a chemical gas phase reaction, the silicon carbide coating is formed on the surface of the graphite base, and in the step of introducing the CO gas into the reaction container and heating, the temperature of the reaction container is higher than 1400 DEG C, and the flow of the CO gas is smaller than 800 sccm. According to the preparation method of the silicon carbide coating graphite base, the compactness of the silicon carbide coating can be well improved, and the embedding depth of the silicon carbide coating in the graphite base can be well increased.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to a silicon carbide coated graphite base and its preparation method and application. Background Art

[0002] With the rapid development of the Light-emitting diode (LED) industry, the demand for LED epitaxial wafers has been increasing continuously. An LED epitaxial wafer refers to a single crystal thin film grown on a substrate wafer, and the quality of the silicon carbide coated graphite base carrying the substrate wafer directly affects the quality of the LED epitaxial wafer. However, in traditional silicon carbide coated graphite bases, the bonding force between the silicon carbide coating and the graphite base is poor, and the embedding depth in the graphite base is insufficient, thus affecting the quality of the LED epitaxial wafer. Summary of the Invention

[0003] Based on this, in view of the above problems, it is necessary to provide a silicon carbide coated graphite base and its preparation method and application. The preparation method of the silicon carbide coating can well control the embedding depth of the silicon carbide coating in the graphite base.

[0004] The present invention discloses a preparation method of a silicon carbide coated graphite base, comprising the following steps:

[0005] Placing SiO powder and the graphite base in a reaction vessel;

[0006] Performing a vacuum pumping treatment on the reaction vessel, introducing CO gas into the reaction vessel and heating. The CO gas and the silicon-containing gas volatilized from the SiO powder undergo a chemical vapor reaction to form a silicon carbide coating with an embedding depth greater than or equal to 200 μm on the surface of the graphite base. Wherein, in the step of introducing CO gas into the reaction vessel and heating, the temperature of the reaction vessel is greater than 1400 °C, and the flow rate of the CO gas is less than 800 sccm.

[0007] In one embodiment, in the step of introducing CO gas, the flow rate of the CO gas is greater than or equal to 600 sccm and less than 800 sccm.

[0008] In one embodiment, in the heating step, the heating rate is 5 °C / min - 10 °C / min.

[0009] In one embodiment, in the heating step, the temperature of the reaction vessel is less than or equal to 1800 °C and greater than 1400 °C.

[0010] In one embodiment, in the step of placing SiO powder and the graphite base in the reaction vessel, the mass ratio of the SiO powder to the graphite base is 1:2 - 1:20.

[0011] In one embodiment, in the step of performing the chemical vapor reaction, the mass of the SiO powder is less than or equal to 1000 g.

[0012] In one embodiment, in the step of performing the chemical vapor reaction, the reaction time is 3 h - 7 h.

[0013] A silicon carbide coated graphite base, prepared by the preparation method of the silicon carbide coated graphite base as described above, includes a graphite base and a silicon carbide coating, the silicon carbide coating is embedded in the graphite base, and the embedding depth of the silicon carbide coating is greater than or equal to 200 μm.

[0014] In one embodiment, the silicon carbide coating includes β-SiC.

[0015] An application of the silicon carbide coated graphite base as described above in the preparation of light emitting diode epitaxial wafers.

[0016] In the preparation method of the silicon carbide coated graphite base provided by the present invention, a single silicon-containing powder and CO gas are used as raw materials to prepare the silicon carbide coating. The CO gas can not only avoid the consumption of carbon on the surface of the graphite base by the silicon-containing gas, but also reduce the concentration of the silicon-containing gas formed by the volatilization of the silicon-containing powder in the reaction vessel when the flow rate of the CO gas is less than 800 sccm, reduce the reaction activity of the silicon-containing gas, slow down the reaction rate of the chemical vapor reaction, deepen the depth of the silicon-containing gas entering the graphite base, and at the same time, the temperature of the reaction vessel is greater than 1400 °C, further deepening the depth of the silicon-containing gas entering the graphite base, and finally well improving the embedding depth of the silicon carbide coating in the graphite base. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 Scanning electron microscope image of the surface of the silicon carbide coated graphite base prepared in Example 1;

[0019] Figure 2 Scanning electron microscope image of the cross-section of the silicon carbide coated graphite base prepared in Example 1;

[0020] Figure 3 X-ray diffraction pattern of the silicon carbide coating prepared in Example 1;

[0021] Figure 4Scanning electron microscope image of the cross-section of the silicon carbide coated graphite base prepared in Example 6;

[0022] Figure 5 Scanning electron microscope image of the surface of the silicon carbide coated graphite base prepared in Example 6;

[0023] Figure 6 Energy spectrum analysis diagram of the silicon carbide coating prepared in Example 6. Detailed implementation manners

[0024] For the convenience of understanding the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosed content of the present invention more thorough and comprehensive.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of the present invention. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments or examples and are not intended to limit the present invention.

[0026] The present invention provides a method for preparing a silicon carbide coated graphite base, comprising the following steps:

[0027] S10, placing a silicon-containing powder and a graphite base in a reaction vessel, the silicon-containing powder being selected from one of SiO powder or Si powder;

[0028] S20, performing a vacuum treatment on the reaction vessel, introducing CO gas into the reaction vessel and heating, the CO gas and the silicon-containing gas volatilized from the silicon-containing powder undergo a chemical vapor reaction to form a silicon carbide coating on the surface of the graphite base. Among them, in the step of introducing CO gas into the reaction vessel and heating, the temperature of the reaction vessel is greater than 1400 °C, and the flow rate of the CO gas is less than 800 sccm.

[0029] In the method for preparing a silicon carbide coated graphite base provided by the present invention, a single silicon-containing powder and CO gas are used as raw materials to prepare a silicon carbide coating. The CO gas can not only prevent the silicon-containing gas from consuming the carbon on the surface of the graphite base, but also the CO gas with a flow rate less than 800 sccm can reduce the concentration of the silicon-containing gas volatilized from the silicon-containing powder in the reaction vessel, reduce the reaction activity of the silicon-containing gas, slow down the reaction rate of the chemical vapor reaction, deepen the depth of the silicon-containing gas entering the graphite base. At the same time, the temperature of the reaction vessel is greater than 1400 °C, which further deepens the depth of the silicon-containing gas entering the graphite base, and finally improves the embedding depth of the silicon carbide coating in the graphite base very well.

[0030] In step S10, in order to improve the bonding force between the silicon carbide coating and the graphite base, in one embodiment, before the step of placing the silicon-containing powder and the graphite base in the reaction vessel, the graphite base is pretreated. Preferably, the pretreatment steps include: first polishing the graphite base with sandpaper, then ultrasonically cleaning the graphite base, and finally drying it; preferably, the graphite base is polished to a roughness less than or equal to 1.6 μm.

[0031] In one embodiment, the graphite base is ultrasonically cleaned with water, and the time for ultrasonic cleaning is 10 min - 30 min, including but not limited to 10 min, 15 min, 20 min, 25 min or 30 min.

[0032] In one embodiment, in the step of placing the silicon-containing powder and the graphite base in the reaction vessel, the graphite base is located on the volatilization path of the silicon-containing powder; preferably, the step of placing the silicon-containing powder and the graphite base in the reaction vessel includes: first placing the silicon-containing powder at the bottom of the graphite crucible, placing the graphite base on the silicon-containing powder, and then placing the crucible containing the silicon-containing powder and the graphite base in the reaction vessel.

[0033] In order to accurately control the raw material components of the chemical vapor reaction and thus control the embedding depth of the silicon carbide coating in the graphite base, in one embodiment, the purity of the silicon-containing powder is greater than or equal to 99.99%.

[0034] In one embodiment, the mass ratio of the silicon-containing powder to the graphite base is 1:2 - 1:20, including but not limited to 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19 or 1:20, so as to ensure that there is a sufficient amount of silicon-containing gas in the reaction vessel.

[0035] In one embodiment, the mass of the silicon-containing powder is less than or equal to 1000 g, including but not limited to, the mass of the silicon-containing powder is 50 g, 100 g, 150 g, 200 g, 250 g, 300 g, 350 g, 400 g, 450 g, 500 g, 550 g, 600 g, 650 g, 700 g, 750 g, 800 g, 850 g, 900 g, 950 g or 1000 g, so as to ensure that there is a sufficient amount of silicon-containing gas in the reaction vessel and at the same time reduce the concentration of silicon-containing gas in the reaction vessel.

[0036] In step S20, during the heating process, the silicon-containing powder volatilizes to form silicon-containing gas, which undergoes a chemical vapor reaction with CO gas to form a silicon carbide coating.

[0037] To better reduce the concentration of silicon-containing gas in the reaction vessel, the steps of introducing CO gas into the reaction vessel and heating include first introducing CO gas into the reaction vessel and then raising the temperature of the reaction vessel.

[0038] In one embodiment, the purity of the CO gas is greater than or equal to 99.99%; thus ensuring the formation of a high-purity silicon carbide coating.

[0039] When the silicon-containing powder is SiO powder, in one embodiment, in the step of introducing CO gas, the flow rate of the CO gas is greater than or equal to 600 sccm and less than 800 sccm, including but not limited to 600 sccm, 650 sccm, 700 sccm, 750 sccm or 790 sccm.

[0040] When the silicon-containing powder is Si powder, in one embodiment, in the step of introducing CO gas, the flow rate of the CO gas is greater than or equal to 400 sccm and less than 800 sccm, including but not limited to 400 sccm, 500 sccm, 600 sccm, 650 sccm, 700 sccm, 750 sccm or 790 sccm.

[0041] In one embodiment, in the heating step, the temperature of the reaction vessel is controlled to be less than or equal to 1800 °C to slow down the reaction rate of the chemical vapor reaction, thereby further improving the uniformity, density and embedding depth of the silicon carbide coating in the graphite base.

[0042] In one embodiment, in the heating step, the heating rate is 5 °C / min - 10 °C / min, including but not limited to 5 °C / min, 6 °C / min, 7 °C / min, 8 °C / min, 9 °C / min or 10 °C / min; thus enabling the temperature of the reaction vessel to rise steadily.

[0043] Under normal pressure (100 kPa), SiO powder exists in solid form from room temperature to 1700 °C. The lower the pressure, the lower the volatilization temperature of SiO powder. In a vacuum environment, when the temperature reaches 1100 °C - 1200 °C, SiO powder will start to volatilize; at the same time, in a vacuum environment, there is no oxygen present, and SiO will not react to form silicon dioxide. Therefore, when the silicon-containing powder is SiO powder, in the heating step, preferably, the temperature of the reaction vessel is less than or equal to 1800 °C and greater than 1400 °C, including but not limited to 1401 °C, 1410 °C, 1420 °C, 1430 °C, 1440 °C, 1450 °C, 1500 °C, 1550 °C, 1600 °C, 1650 °C, 1700 °C, 1750 °C, 1790 °C or 1800 °C.

[0044] In one embodiment, in the step of vacuum pumping treatment, the absolute pressure of the reaction vessel is less than or equal to 10 Pa, including but not limited to 0 Pa, 1 Pa, 2 Pa, 3 Pa, 4 Pa, 5 Pa, 6 Pa, 7 Pa, 8 Pa, 9 Pa or 10 Pa.

[0045] In one embodiment, when the silicon-containing powder is SiO powder, in the step of chemical vapor reaction, the reaction time is 3 h - 7 h, including but not limited to 3 h, 4 h, 5 h, 6 h or 7 h.

[0046] In one embodiment, when the silicon-containing powder is Si powder, in the step of chemical vapor reaction, the reaction time is 2 h - 5 h, including but not limited to 2 h, 3 h, 4 h or 5 h.

[0047] The present invention also provides a silicon carbide coated graphite base obtained by the preparation method, including a graphite base and a silicon carbide coating, and the silicon carbide coating is embedded in the graphite base.

[0048] In one embodiment, when the silicon-containing powder is SiO powder, the embedding depth of the silicon carbide coating is greater than or equal to 200 μm, including but not limited to 200 μm, 225 μm, 250 μm, 275 μm, 300 μm, 325 μm, 350 μm, 375 μm, 400 μm, 425 μm, 450 μm, 475 μm or 500 μm.

[0049] In one embodiment, when the silicon-containing powder is Si powder, the embedding depth of the silicon carbide coating is greater than or equal to 50 μm, including but not limited to 50 μm, 75 μm, 100 μm, 125 μm, 150 μm, 175 μm, 200 μm, 225 μm, 250 μm, 275 μm, 300 μm, 325 μm, 350 μm, 375 μm, 400 μm, 425 μm, 450 μm, 475 μm or 500 μm.

[0050] In one embodiment, the silicon carbide coating is mainly composed of β-SiC, and the thickness of the silicon carbide coating is 30 μm - 100 μm, including but not limited to 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm.

[0051] The present invention also provides an application of the silicon carbide coated graphite base as described above in the preparation of light-emitting diode epitaxial wafers.

[0052] The silicon carbide coated graphite base provided by the present invention has excellent uniformity, density and embedding depth in the graphite base. Using this silicon carbide coated graphite base to carry the substrate wafer for growing LED epitaxial wafers can well improve the quality of LED epitaxial wafers.

[0053] Hereinafter, the silicon carbide coated graphite base, its preparation method and application will be further described through the following specific examples.

[0054] Example 1

[0055] The graphite base was polished with sandpaper, ultrasonically cleaned with pure water for 20 min, and then placed in an oven and dried at 130 °C for 3 h to obtain a pretreated graphite base.

[0056] First, 100 g of SiO powder was placed at the bottom of a graphite crucible, and then 600 g of the pretreated graphite base was placed on the SiO powder. The graphite crucible containing the SiO powder and the pretreated graphite base was placed in a vacuum furnace.

[0057] The vacuum furnace was evacuated, then heated to 1600 °C at a rate of 10 °C / min, and then 600 sccm of CO gas was introduced to carry out a chemical vapor reaction with the SiO gas volatilized from the SiO powder. After holding for 4 h, a silicon carbide coating was formed on the surface of the graphite base to obtain a silicon carbide coated graphite base.

[0058] Scanning electron microscopic analysis was performed on the surface and cross-section of the silicon carbide coated graphite base, and the analysis results are as Figure 1 and Figure 2 shown. It can be seen from Figure 1 that a dense silicon carbide coating was formed on the graphite base; it can be seen from Figure 2 that the silicon carbide coating was deeply embedded in the graphite base, indicating a high bonding strength between the silicon carbide coating and the graphite matrix. Figure 3 is the X-ray diffraction pattern of the silicon carbide coating. It can be seen from Figure 3 that the silicon carbide coating is mainly composed of the β-SiC phase.

[0059] Comparative Example 1

[0060] The graphite base was polished with sandpaper, ultrasonically cleaned with pure water for 20 min, and then placed in an oven and dried at 130 °C for 3 h to obtain a pretreated graphite base.

[0061] First, 100 g of SiO powder was placed at the bottom of a graphite crucible, and then 600 g of the pretreated graphite base was placed on the SiO powder. The graphite crucible containing the SiO powder and the pretreated graphite base was placed in a vacuum furnace.

[0062] The vacuum furnace was evacuated, then heated to 1600 °C at a rate of 10 °C / min, and held for 4 h to form a silicon carbide coating on the surface of the graphite base to obtain a silicon carbide coated graphite base.

[0063] Comparative Example 2

[0064] The graphite base was polished with sandpaper and ultrasonically cleaned with pure water for 20 min, then placed in an oven and dried at 130 °C for 3 h to obtain a pretreated graphite base.

[0065] First, the mixed powder of Si and SiO 2 was placed at the bottom of a graphite crucible, and then 600 g of the pretreated graphite base was placed on the SiO powder. The SiO powder and the pretreated graphite base were placed in a vacuum furnace. Among them, the molar ratio of Si to SiO 2 was 1:1, and the total mass of Si and SiO 2 was the same as that of the SiO powder.

[0066] The vacuum furnace was evacuated, then heated to 1600 °C at a rate of 10 °C / min, and then 600 sccm of CO gas was introduced to carry out a chemical vapor reaction with the SiO gas volatilized from the SiO powder. After holding for 4 h, a silicon carbide coating was formed on the surface of the graphite base to obtain a graphite base with a silicon carbide coating.

[0067] Comparative Example 3

[0068] The graphite base was polished with sandpaper and ultrasonically cleaned with pure water for 20 min, then placed in an oven and dried at 130 °C for 3 h to obtain a pretreated graphite base.

[0069] First, 100 g of SiO powder was placed at the bottom of a graphite crucible, and then 600 g of the pretreated graphite base was placed on the SiO powder. The SiO powder and the pretreated graphite base were placed in a vacuum furnace.

[0070] The vacuum furnace was evacuated, then heated to 1600 °C at a rate of 10 °C / min, and then 1000 sccm of CO gas was introduced to carry out a chemical vapor reaction with the SiO gas volatilized from the SiO powder. After holding for 4 h, a silicon carbide coating was formed on the surface of the graphite base to obtain a graphite base with a silicon carbide coating.

[0071] Comparative Example 4

[0072] The graphite base was polished with sandpaper and ultrasonically cleaned with pure water for 20 min, then placed in an oven and dried at 130 °C for 3 h to obtain a pretreated graphite base.

[0073] First, 100 g of SiO powder was placed at the bottom of a graphite crucible, and then 600 g of the pretreated graphite base was placed on the SiO powder. The SiO powder and the pretreated graphite base were placed in a vacuum furnace.

[0074] The vacuum furnace was evacuated, then heated to 1600 °C at a rate of 10 °C / min. Subsequently, 800 sccm of CO gas was introduced to carry out a chemical vapor reaction with the SiO gas formed by the volatilization of SiO powder. After holding for 4 h, a silicon carbide coating was formed on the surface of the graphite base to obtain a graphite base with a silicon carbide coating.

[0075] Comparative Example 5

[0076] The graphite base was polished with sandpaper and ultrasonically cleaned with pure water for 20 min, then placed in an oven and dried at 130 °C for 3 h to obtain a pretreated graphite base.

[0077] First, 100 g of SiO powder was placed at the bottom of a graphite crucible, and then 600 g of the pretreated graphite base was placed on the SiO powder. The SiO powder and the pretreated graphite base were placed in a vacuum furnace.

[0078] The vacuum furnace was evacuated, then heated to 1300 °C at a rate of 10 °C / min. Subsequently, 600 sccm of CO gas was introduced to carry out a chemical vapor reaction with the SiO gas formed by the volatilization of SiO powder. After holding for 4 h, a silicon carbide coating was formed on the surface of the graphite base to obtain a graphite base with a silicon carbide coating.

[0079] Test Example 1

[0080] The embedding depth in the graphite bases with silicon carbide coatings prepared in Test Example 1 and Comparative Examples 1 to 5 was measured. The test method is as follows, and the test results are shown in Table 1.

[0081] Embedding depth in the graphite base: The embedding depth of the silicon carbide coating in the graphite base was measured with a scanning electron microscope.

[0082] Density: The surface was observed with a scanning electron microscope, and whether it was dense was judged according to the exposure of graphite on the surface. The higher the density, the smaller the porosity, and vice versa, the larger the porosity.

[0083] Table 1

[0084] Embedding depth in the graphite base Whether it is dense Example 1 300μm Yes Comparative Example 1 550μm No Comparative Example 2 250μm Yes Comparative Example 3 150μm Yes Comparative Example 4 210μm Yes Comparative Example 5 50μm No

[0085] Example 2

[0086] The graphite base was polished with sandpaper and ultrasonically cleaned with pure water for 20 min, then placed in an oven and dried at 130 °C for 3 h to obtain a pretreated graphite base.

[0087] First, place 100 g of SiO powder at the bottom of a graphite crucible, then place 600 g of pretreated graphite base on the SiO powder, and place the graphite crucible containing the SiO powder and the pretreated graphite base into a vacuum furnace.

[0088] Perform vacuum pumping on the vacuum furnace, then heat it up to 1900 °C at a rate of 10 °C / min. Then, introduce 600 sccm of CO gas to carry out a chemical vapor reaction with the SiO gas volatilized from the SiO powder, hold the temperature for 4 h, and form a silicon carbide coating on the surface of the graphite base to obtain a graphite base with a silicon carbide coating.

[0089] Example 3

[0090] Use sandpaper to polish the graphite base, ultrasonically clean the graphite base with pure water for 20 min, and then place it in an oven and dry it at 130 °C for 3 h to obtain a pretreated graphite base.

[0091] First, place 100 g of SiO powder at the bottom of a graphite crucible, then place 600 g of pretreated graphite base on the SiO powder, and place the graphite crucible containing the SiO powder and the pretreated graphite base into a vacuum furnace.

[0092] Perform vacuum pumping on the vacuum furnace, then heat it up to 1800 °C at a rate of 10 °C / min. Then, introduce 600 sccm of CO gas to carry out a chemical vapor reaction with the SiO gas volatilized from the SiO powder, hold the temperature for 4 h, and form a silicon carbide coating on the surface of the graphite base to obtain a graphite base with a silicon carbide coating.

[0093] Example 4

[0094] Use sandpaper to polish the graphite base, ultrasonically clean the graphite base with pure water for 20 min, and then place it in an oven and dry it at 130 °C for 3 h to obtain a pretreated graphite base.

[0095] First, place 200 g of SiO powder at the bottom of a graphite crucible, then place 600 g of pretreated graphite base on the SiO powder, and place the graphite crucible containing the SiO powder and the pretreated graphite base into a vacuum furnace.

[0096] Perform vacuum pumping on the vacuum furnace, then heat it up to 1600 °C at a rate of 10 °C / min. Then, introduce 600 sccm of CO gas to carry out a chemical vapor reaction with the SiO gas volatilized from the SiO powder, hold the temperature for 4 h, and form a silicon carbide coating on the surface of the graphite base to obtain a graphite base with a silicon carbide coating.

[0097] Example 5

[0098] The graphite base was polished with sandpaper, ultrasonically cleaned with pure water for 20 min, and then dried in an oven at 130 °C for 3 h to obtain a pretreated graphite base.

[0099] First, 300 g of SiO powder was placed at the bottom of a graphite crucible, and then 600 g of the pretreated graphite base was placed on the SiO powder. The SiO powder and the pretreated graphite base were placed in a vacuum furnace.

[0100] The vacuum furnace was evacuated, then heated to 1600 °C at a rate of 10 °C / min. Then, 600 sccm of CO gas was introduced to carry out a chemical vapor reaction with the SiO gas volatilized from the SiO powder, and the temperature was maintained for 4 h to form a silicon carbide coating on the surface of the graphite base, obtaining a graphite base with a silicon carbide coating.

[0101] Test Example 2

[0102] Referring to Test Example 1, the embedding depth of the silicon carbide coatings prepared in Examples 2 to 5 in the graphite base was tested, and the test results are shown in Table 2.

[0103] Table 2

[0104] Embedding depth in the graphite base Whether it is dense Example 2 700μm Yes Example 3 600μm Yes Example 4 420μm Yes Example 5 510μm Yes

[0105] Example 6

[0106] The graphite base was polished with sandpaper, ultrasonically cleaned with pure water for 20 min, and then dried in an oven at 120 °C for 2 h to obtain a pretreated graphite base.

[0107] First, 100 g of Si powder was placed at the bottom of a graphite crucible, and then 600 g of the pretreated graphite base was placed on the Si powder. The Si powder and the pretreated graphite base were placed in a vacuum furnace.

[0108] The vacuum furnace was evacuated, then heated to 1700 °C at a rate of 10 °C / min. Then, 400 sccm of CO gas was introduced to carry out a chemical vapor reaction with the Si gas volatilized from the Si powder, and the temperature was maintained for 3 h to form a silicon carbide coating on the surface of the graphite base, obtaining a graphite base with a silicon carbide coating.

[0109] The cross-section and surface of the graphite base with a silicon carbide coating were analyzed by scanning electron microscopy, and the analysis results are as Figure 4 and Figure 5 shown. From Figure 4It can be seen that the white part is the silicon carbide coating. The silicon carbide coating has a very deep embedding depth, greater than 300 μm. The bonding force between the silicon carbide coating and the graphite base is high, the strength of the silicon carbide coating is high, and it has excellent thermal shock resistance; from Figure 5 It can be seen that the surface of the silicon carbide coating is continuous, and the generated silicon carbide grains are between 10 μm and 40 μm; Figure 6 It is the energy spectrum analysis diagram of the silicon carbide coating. From Figure 6 it can be seen that the silicon carbide coating is composed of two elements, Si and C.

[0110] Example 7

[0111] Example 7 was carried out with reference to Example 6, except that the temperature was raised to 1800 °C at a rate of 10 °C / min; the flow rate of CO gas was 600 sccm.

[0112] Comparative Example 6

[0113] Comparative Example 6 was carried out with reference to Example 6, except that the temperature of the reaction vessel was raised to 1400 °C at a heating rate of 10 °C / min.

[0114] Test Example 3

[0115] With reference to Test Example 1, the embedding depths of the silicon carbide coatings prepared in Example 6, Example 7, and Comparative Example 6 in the graphite base were tested, and the test results are shown in Table 3.

[0116] Table 3

[0117] Embedding depth in the graphite base Whether it is dense Example 6 630μm Yes Example 7 750μm Yes Comparative Example 6 150μm Yes

[0118] Example 8

[0119] Example 8 was carried out with reference to Example 6, except that the flow rate of CO gas was 1000 sccm.

[0120] Example 9

[0121] Example 9 was carried out with reference to Example 6, except that the flow rate of CO gas was 700 sccm.

[0122] Example 10

[0123] Example 10 was carried out with reference to Example 6, except that the mass of Si powder was 200 g.

[0124] Example 11

[0125] Example 11 was carried out with reference to Example 6, except that the mass of Si powder was 300 g.

[0126] Test Example 4

[0127] The embedding depths of the silicon carbide coatings prepared in Examples 8 to 11 were tested with reference to Test Example 1, and the test results are shown in Table 4.

[0128] Table 4

[0129] Embedding depth in the graphite base Whether it is dense Example 8 400μm Yes Example 9 530μm Yes Example 10 700μm Yes Example 11 780μm Yes

[0130] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0131] The above-described embodiments only represent several implementation manners of the present invention, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A method for preparing a silicon carbide coated graphite susceptor, characterized in that: The following steps are involved: Placing SiO powder and graphite base in a reaction container; The reaction container is vacuumed, CO gas is introduced into the reaction container and heated, the CO gas reacts with the silicon-containing gas formed by the volatilization of the SiO powder to form a chemical vapor phase reaction, and a silicon carbide coating with an embedding depth greater than or equal to 200 μm is formed on the surface of the graphite base, wherein in the step of introducing CO gas into the reaction container and heating, the temperature of the reaction container is greater than 1400° C., and the flow rate of the CO gas is less than 800 sccm.

2. The method for preparing a silicon carbide coated graphite susceptor according to claim 1, characterized in that: In the step of introducing CO gas, the flow rate of the CO gas is greater than or equal to 600 sccm and less than 800 sccm.

3. The method for preparing a silicon carbide coated graphite susceptor according to claim 1, characterized in that: In the heating step, the heating rate is 5°C / min-10°C / min.

4. The method for preparing a silicon carbide coated graphite susceptor according to any one of claims 1 to 3, characterized in that: In the heating step, the temperature of the reaction container is less than or equal to 1800°C and greater than 1400°C.

5. The method for preparing a silicon carbide coated graphite susceptor according to any one of claims 1 to 3, characterized in that: In the step of placing SiO powder and a graphite base in a reaction container, the mass ratio of the SiO powder to the graphite base is 1:2-1:

20.

6. The method for preparing a silicon carbide coated graphite susceptor according to claim 5, characterized in that: In the step of performing a chemical vapor reaction, the mass of the SiO powder is less than or equal to 1000 g.

7. The method for preparing a silicon carbide coated graphite susceptor according to any one of claims 1 to 3, characterized in that: In the step of performing the chemical vapor reaction, the reaction time is 3h-7h.

8. A silicon carbide coated graphite susceptor, characterized in that: The method for preparing a silicon carbide coated graphite base according to any one of claims 1 to 7 comprises a graphite base and a silicon carbide coating, wherein the silicon carbide coating is embedded in the graphite base, and the embedding depth of the silicon carbide coating is greater than or equal to 200 μm.

9. The silicon carbide coated graphite susceptor according to claim 8, characterized in that: The silicon carbide coating includes β-SiC.

10. Use of the silicon carbide coated graphite susceptor according to claim 8 or claim 9 in preparing light emitting diode epitaxial wafers.

Images