Method for repairing SiC coating on graphite disk surface using MOCVD system

Abstract

The present application discloses a method for repairing SiC coating on the surface of graphite disk by using MOCVD system, which relates to the field of semiconductor device technology, and comprises the following steps: placing the graphite disk to be repaired into the reaction chamber of MOCVD system, introducing SiH4 and C3H8 for repair reaction, and obtaining a graphite disk with SiC coating on the surface; the temperature of the repair reaction is 1245-1255°C; the pressure of the repair reaction is 190-210torr; the volume flow rate of SiH4 is Q1, and the volume flow rate of C3H8 is Q2, which satisfies: 3≤Q2 / Q1≤7.5. The present application improves the deposition rate of SiC on the surface of graphite disk by controlling the pressure of the repair reaction within a suitable range and coordinating and regulating the flow rate ratio of the growth source in the repair reaction, and the suitable deposition rate is conducive to the growth of SiC coating, and deposition within a suitable time range can improve the cycle life of graphite disk.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor devices, and in particular to a method for repairing a SiC coating on the surface of a graphite disk by using an MOCVD system. Background Art

[0002] The MOCVD system is mainly used in the preparation of semiconductor materials, devices and thin films. It uses organic compounds of group III and group II elements and hydrides of group V and VI elements as crystal growth source materials, and performs vapor phase epitaxy on the substrate in a thermal decomposition reaction mode to grow various thin-layer single crystal materials of group III-V, group II-VI compound semiconductors and their multi-component solid solutions. The substrate is an important component in the MOCVD reaction chamber, which is used to support the growth of thin-layer single crystals, mainly graphite disks coated with SiC coatings. For special epitaxial wafer processes, the graphite disk needs to be placed in the reaction chamber of the MOCVD system when it is reused and Cl2 is passed through its surface under high temperature conditions to bake it. However, Cl2 will have a certain corrosive effect on the SiC coating on the surface of the graphite disk, which will significantly reduce the service life of the graphite disk, which is not conducive to the control of production costs. Summary of the invention

[0003] The present application provides a method for repairing the SiC coating on the surface of a graphite disk by using an MOCVD system. In the production process, no other repair equipment is required. The SiC coating on the surface of the graphite disk can be repaired only by controlling various parameters in the MOCVD system. The repaired SiC coating is more delicate, uniform and dense, and can significantly extend the service life of the graphite disk.

[0004] In the first aspect, the present application provides a method for repairing the SiC coating on the surface of a graphite disk using an MOCVD system, comprising the following steps: placing the graphite disk to be repaired into a reaction chamber of the MOCVD system, introducing SiH4 and C3H8 into a repair reaction to obtain a graphite disk having a surface covered with a SiC coating, the temperature of the repair reaction being 1245-1255°C, the pressure of the repair reaction being 190-210 torr, the volume flow rate of the SiH4 being Q1, the volume flow rate of the C3H8 being Q2, and satisfying: 3≤Q2 / Q1≤7.5. The present application is to place a graphite disk to be repaired into a reaction chamber of an MOCVD system, wherein the graphite disk to be repaired may be a graphite disk corroded by Cl2 or an unused graphite disk. In the unused graphite disk, the surface is mainly uneven when it leaves the factory, and the concave position is easily corroded during subsequent use, making the graphite disk exposed; after the graphite disk to be repaired is placed in position, SiH4 and C3H8 are introduced into the reaction chamber for a repair reaction, which mainly involves the following reaction: 3SiH4+C3H8=3SiC+10H2. At the same time, the present application controls the temperature and pressure of the repair reaction within a suitable range and coordinately controls the flow ratio of the reactants in the repair reaction to be appropriate. At this time, on the one hand, the appropriate flow ratio can improve the utilization rate of silane (C3H8), promote the forward progress of the reaction, and increase the reaction rate. On the other hand, the appropriate reaction pressure and the appropriate flow ratio can cooperate to control the deposition rate of the generated SiC on the surface of the graphite disk, which is beneficial to the growth of the SiC coating.

[0005] Exemplarily, the temperature of the repair reaction is 1245°C, 1248°C, 1250°C, 1252°C, 1254°C, 1255°C or a range consisting of any two of the above values.

[0006] Exemplarily, the pressure of the repair reaction is 190 torr, 195 torr, 200 torr, 205 torr, 210 torr or a range consisting of any two of the above values.

[0007] Exemplarily, the ratio Q2 / Q1 of the volume flow rate Q2 of C3H8 to the volume flow rate Q1 of SiH4 is 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5 or a range consisting of any two of the above values.

[0008] In some embodiments, the method satisfies at least one of the following conditions: Condition I: 100≤Q1≤150; Condition II: 500≤Q2≤750. At this time, the flow rates of SiH4 (silane) and C3H8 (propane) as growth sources are appropriate. Under the coordination of appropriate pressure and appropriate growth source flow rates, the deposition rate of the SiC coating can be improved. When 3≤Q2 / Q1≤7.5 is satisfied, the deposition rate of the SiC coating can be controlled at 2-4 nm / min. The grown SiC coating has good density and a fine surface, which is beneficial to improving the corrosion resistance of the graphite disk.

[0009] Exemplarily, the volume flow rate Q1 of SiH4 is 100 sccm, 110 sccm, 120 sccm, 130 sccm, 140 sccm, 150 sccm or a range consisting of any two of the above values.

[0010] Exemplarily, the volume flow rate Q2 of C3H8 is 500sccm, 550sccm, 600sccm, 650sccm, 700sccm, 750sccm or a range consisting of any two of the above values.

[0011] In some embodiments, the pressure of the repair reaction is 195-205 torr; and 4.6≤Q2 / Q1≤5.0 is satisfied. At this time, the deposition rate of the SiC coating can be controlled at about 3 nm / min, which is more conducive to the growth of the SiC coating.

[0012] Exemplarily, the ratio Q2 / Q1 of the volume flow rate Q2 of the C3H8 and the volume flow rate Q1 of the SiH4 is 4.6, 4.7, 4.8, 4.9, 5.0 or a range consisting of any two of the above values.

[0013] In some embodiments, at least one of the following conditions is satisfied: Condition III: 128≤Q1≤132; Condition IV: 622≤Q2≤626. In this case, the flow rate of the growth source is more appropriate, which is more conducive to the coordinated cooperation with the pressure of the repair reaction, and the prepared SiC coating has better performance.

[0014] Exemplarily, the volume flow rate Q1 of SiH4 is 128 sccm, 129 sccm, 130 sccm, 131 sccm, 132 sccm or a range consisting of any two of the above values.

[0015] Exemplarily, the volume flow rate Q2 of C3H8 is 622sccm, 623sccm, 624sccm, 625sccm, 626sccm or a range consisting of any two of the above values.

[0016] In some embodiments, the rotation speed of the graphite disk is V r / min, which satisfies: 0.55≤(Q1+Q2) / V≤0.75. Preferably, it satisfies: 0.65≤(Q1+Q2) / V≤0.67. By controlling the rotation speed of the graphite disk within a suitable range, the grown SiC coating is facilitated to uniformly cover the surface of the graphite disk.

[0017] Exemplarily, (Q1+Q2) / V is 0.55, 0.58, 0.6, 0.62, 0.64, 0.65, 0.66, 0.67, 0.68, 0.7, 0.73, 0.75 or a range consisting of any two of the above values.

[0018] In some embodiments, the rotation speed of the graphite disk is 1145-1155 r / min. At this time, the grown SiC coating is more evenly distributed on the surface of the graphite disk, which is beneficial to improving the service life of the graphite disk.

[0019] Exemplarily, the rotational speed of the graphite disk is 1145 r / min, 1148 r / min, 1150 r / min, 1152 r / min, 1154 r / min, 1155 r / min or a range consisting of any two of the above values.

[0020] In some embodiments, the repair reaction time is 30 to 35 minutes. At this time, the thickness of the SiC coating on the surface of the graphite disk can be controlled between 90 and 110 nm. If the thickness of the SiC coating is too thin (for example, less than 90 nm), it will not play a role in repairing the graphite disk, that is, the improvement of corrosion resistance is not significant. If the thickness of the SiC coating is too thick (for example, greater than 110 nm), it will affect the subsequent production yield.

[0021] Exemplarily, the repair reaction time is 30 min, 31 min, 32 min, 33 min, 34 min, 35 min or a range consisting of any two of the above values.

[0022] In some embodiments, the graphite disk to be repaired is placed in the reaction chamber of the MOCVD system, and before SiH4 and C3H8 are introduced, the process also includes: pre-treating the surface of the graphite disk, wherein H2 is introduced into the reaction chamber for pre-treatment reaction; the temperature of the pre-treatment reaction is 1140-1160°C, preferably 1150°C; the pressure of the pre-treatment reaction is 74-76 torr, preferably 75 torr; the rotation speed of the graphite disk is 595-605 r / min, preferably 600 r / min; the volume flow rate of H2 is 88-92 slm, preferably 90 slm; the time of the pre-treatment reaction is 5-7 min, preferably 6 min. The above pre-treatment conditions can remove some residual impurities such as GaN on the surface of the graphite disk, and will not affect the SiC coating on the surface of the graphite disk.

[0023] In some embodiments, after the repair reaction is completed, N2 is introduced into the reaction chamber for post-treatment reaction, and the temperature is cooled to 400°C at a cooling rate of 1.4-1.6°C / s, preferably 1.5°C / s, and then naturally cooled to room temperature; the volume flow rate of N2 is 95-105slm, preferably 100slm; the pressure of the post-treatment reaction is 75-80torr, preferably 80torr. At this time, it is beneficial to improve the fit between the SiC coating and the surface of the graphite disk, making the grown SiC coating more solid, thereby improving the corrosion resistance of the surface of the graphite disk, and making the service life of the graphite disk longer.

[0024] The beneficial effects brought about by the technical solutions provided by some embodiments of the present application include at least:

[0025] The present application provides a method for repairing a SiC coating on the surface of a graphite disk by using an MOCVD system. By controlling the pressure of a repair reaction within a suitable range and coordinating and regulating the flow rate ratio of a growth source in the repair reaction to be appropriate, the deposition rate of SiC on the surface of the graphite disk is improved. The appropriate deposition rate is conducive to the growth of the SiC coating. The grown SiC coating is more delicate, has a good density, and has a stronger corrosion resistance, thereby improving the cycle life of the graphite disk. Furthermore, by controlling the rotation speed of the graphite disk within a suitable range, the rotation speed of the graphite disk is coordinated with the pressure of the reaction chamber and the flow rate of the growth source, so that the surface of the graphite disk can be fully covered with the SiC coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 is a diagram of the surface of the graphite disk to be repaired in Example 1 of the present application;

[0028] Figure 2 It is a diagram of the surface of the graphite disk after repair in Example 1 of the present application;

[0029] Figure 3 This is a diagram showing the corrosion of the repaired graphite disk of Example 1 of the present application after 230 uses. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments and drawings. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0031] The present application is further described below by way of examples.

[0032] Example 1

[0033] Step 1: Place the graphite disk to be repaired into the reaction chamber of the MOCVD system and introduce H2 to pretreat the surface of the graphite disk. At a rate of 1°C / s, increase the temperature of the reaction chamber to 1150°C, adjust the pressure of the reaction chamber to 75torr, set the rotation speed of the graphite disk to 600 / min, control the volume flow rate of the introduced H2 to 90slm, and stop introducing H2 after 6 minutes of pretreatment reaction;

[0034] Step 2: Raise the temperature of the reaction chamber to 1250°C, adjust the pressure of the reaction chamber to 190 torr, set the rotation speed of the graphite disk to 1145 r / min, and at the same time, introduce SiH4 gas and C3H8 gas, control the volume flow rate of the introduced SiH4 to 150 sccm, and control the volume flow rate of the introduced C3H8 to 500 sccm. After reacting for 33 minutes, stop introducing SiH4 gas and C3H8 gas;

[0035] Step 3: The pressure of the reaction chamber was reduced to 80 torr, N2 was introduced into the reaction chamber for post-treatment reaction, the volume flow of N2 was controlled to be 100 slm, and the temperature was reduced to 400°C at a cooling rate of 1.5°C / s, and then naturally cooled to room temperature. When the repaired graphite disk in Example 1 was put into the MOCVD system and continued to be used, corrosion spots did not appear until 230 cycles, and the average diameter of the corrosion spots was about 0.1 mm.

[0036] Figure 1The surface of the graphite disk to be repaired in Example 1 of the present application is a common commercially available graphite disk. The whitish position on the surface of the graphite disk is the corrosion condition of the surface of the commercially available graphite disk when it is used about 180 to 200 times. The diameter of the corrosion point is between 1 and 5 mm.

[0037] Figure 2 This is the surface of the repaired graphite disk in Example 1 of the present application. It can be seen that the coating on the surface of the repaired graphite disk is fine, uniform and dense;

[0038] Figure 3 This is the surface corrosion condition of the repaired graphite disk of Example 1 of the present application after being used 230 times. Points A, B and C in the figure are all corrosion points, and the average diameter of the corrosion points is about 0.1 mm.

[0039] Example 2

[0040] Step 1: Place the graphite disk to be repaired into the reaction chamber of the MOCVD system and introduce H2 to pretreat the surface of the graphite disk. At a rate of 1°C / s, increase the temperature of the reaction chamber to 1150°C, adjust the pressure of the reaction chamber to 75torr, set the rotation speed of the graphite disk to 600 / min, control the volume flow rate of the introduced H2 to 90slm, and stop introducing H2 after 6 minutes of pretreatment reaction;

[0041] Step 2: Raise the temperature of the reaction chamber to 1250°C, adjust the pressure of the reaction chamber to 210 torr, set the rotation speed of the graphite disk to 1155 r / min, and at the same time, introduce SiH4 gas and C3H8 gas, control the volume flow rate of the introduced SiH4 to 100 sccm, and control the volume flow rate of the introduced C3H8 to 750 sccm. Stop introducing SiH4 gas and C3H8 gas after reacting for 33 minutes;

[0042] Step 3: The pressure of the reaction chamber was reduced to 80 torr, N2 was introduced into the reaction chamber for post-treatment reaction, the volume flow of N2 was controlled to be 100 slm, and the temperature was reduced to 400°C at a cooling rate of 1.5°C / s, and then naturally cooled to room temperature. When the repaired graphite disk in Example 2 was put into the MOCVD system and continued to be used, corrosion spots did not appear until the cycle was 220 times, and the average diameter of the corrosion spots was about 0.1 mm.

[0043] Example 3

[0044] Step 1: Place the graphite disk to be repaired into the reaction chamber of the MOCVD system and introduce H2 to pretreat the surface of the graphite disk. At a rate of 1°C / s, increase the temperature of the reaction chamber to 1150°C, adjust the pressure of the reaction chamber to 75torr, set the rotation speed of the graphite disk to 600 / min, control the volume flow rate of the introduced H2 to 90slm, and stop introducing H2 after 6 minutes of pretreatment reaction;

[0045] Step 2: Raise the temperature of the reaction chamber to 1250°C, adjust the pressure of the reaction chamber to 200 torr, set the rotation speed of the graphite disk to 1150 r / min, and at the same time, introduce SiH4 gas and C3H8 gas, control the volume flow rate of the introduced SiH4 to 130 sccm, and control the volume flow rate of the introduced C3H8 to 624 sccm. Stop introducing SiH4 gas and C3H8 gas after reacting for 33 minutes;

[0046] Step 3: The pressure of the reaction chamber was reduced to 80 torr, N2 was introduced into the reaction chamber for post-treatment reaction, the volume flow rate of N2 was controlled to be 100 slm, and the temperature was reduced to 400°C at a cooling rate of 1.5°C / s, and then naturally cooled to room temperature. When the repaired graphite disk in Example 3 was put into the MOCVD system and continued to be used, corrosion spots did not appear until 250 cycles, and the average diameter of the corrosion spots was about 0.1 mm.

[0047] Example 4

[0048] Step 1: Place the graphite disk to be repaired into the reaction chamber of the MOCVD system and introduce H2 to pretreat the surface of the graphite disk. At a rate of 1°C / s, increase the temperature of the reaction chamber to 1150°C, adjust the pressure of the reaction chamber to 75torr, set the rotation speed of the graphite disk to 600 / min, control the volume flow rate of the introduced H2 to 90slm, and stop introducing H2 after 6 minutes of pretreatment reaction;

[0049] Step 2: Raise the temperature of the reaction chamber to 1250°C, adjust the pressure of the reaction chamber to 200 torr, set the rotation speed of the graphite disk to 1885 r / min, and at the same time, introduce SiH4 gas and C3H8 gas, control the volume flow rate of the introduced SiH4 to 130 sccm, and control the volume flow rate of the introduced C3H8 to 624 sccm. After reacting for 30 minutes, stop introducing SiH4 gas and C3H8 gas;

[0050] Step 3: Reduce the pressure of the reaction chamber to 80torr, introduce N2 into the reaction chamber for post-treatment reaction, control the volume flow of N2 to 100slm, and cool to 400°C at a cooling rate of 1.5°C / s, and then cool naturally to room temperature. When the repaired graphite disk in Example 4 is put into the MOCVD system and continues to be used, corrosion spots will appear after 180 cycles. This is because the rotation speed of the graphite disk is too fast, resulting in uneven deposition of the SiC coating. The average diameter of the corrosion spots is about 1mm.

[0051] Example 5

[0052] Step 1: Place the graphite disk to be repaired into the reaction chamber of the MOCVD system and introduce H2 to pretreat the surface of the graphite disk. At a rate of 1°C / s, increase the temperature of the reaction chamber to 1150°C, adjust the pressure of the reaction chamber to 75torr, set the rotation speed of the graphite disk to 600 / min, control the volume flow rate of the introduced H2 to 90slm, and stop introducing H2 after 6 minutes of pretreatment reaction;

[0053] Step 2: Raise the temperature of the reaction chamber to 1250°C, adjust the pressure of the reaction chamber to 200 torr, set the rotation speed of the graphite disk to 754 r / min, and at the same time, introduce SiH4 gas and C3H8 gas, control the volume flow rate of the introduced SiH4 to 130 sccm, and control the volume flow rate of the introduced C3H8 to 624 sccm. After reacting for 30 minutes, stop introducing SiH4 gas and C3H8 gas;

[0054] Step 3: Reduce the pressure of the reaction chamber to 80torr, introduce N2 into the reaction chamber for post-treatment reaction, control the volume flow of N2 to 100slm, and cool to 400°C at a cooling rate of 1.5°C / s, and then cool naturally to room temperature. When the repaired graphite disk in Example 5 was put into the MOCVD system and continued to be used, corrosion spots appeared after 141 cycles. This is because the rotation speed of the graphite disk is too low, resulting in too thick a coating, which is prone to cracks during use, resulting in a significant reduction in cycle life. The average diameter of the corrosion spots is 1.5mm.

[0055] Example 6

[0056] Step 1: Place the graphite disk to be repaired into the reaction chamber of the MOCVD system and introduce H2 to pretreat the surface of the graphite disk. At a rate of 1°C / s, increase the temperature of the reaction chamber to 1150°C, adjust the pressure of the reaction chamber to 75torr, set the rotation speed of the graphite disk to 600 / min, control the volume flow rate of the introduced H2 to 90slm, and stop introducing H2 after 6 minutes of pretreatment reaction;

[0057] Step 2: Raise the temperature of the reaction chamber to 1250°C, adjust the pressure of the reaction chamber to 200 torr, set the rotation speed of the graphite disk to 1150 r / min, and at the same time, introduce SiH4 gas and C3H8 gas, control the volume flow rate of the introduced SiH4 to 180 sccm, and control the volume flow rate of the introduced C3H8 to 990 sccm. After reacting for 30 minutes, stop introducing SiH4 gas and C3H8 gas;

[0058] Step 3: Reduce the pressure of the reaction chamber to 80torr, introduce N2 into the reaction chamber for post-treatment reaction, control the volume flow of N2 to 100slm, and cool to 400°C at a cooling rate of 1.5°C / s, and then cool naturally to room temperature. When the repaired graphite disk in Example 6 was put into the MOCVD system and continued to be used, corrosion spots appeared after 143 cycles. This is because the flow ratio of silane and propane is not suitable, which is not conducive to the growth of SiC coating. The average diameter of the corrosion spots is 0.8mm.

[0059] Example 7

[0060] Step 1: Place the graphite disk to be repaired into the reaction chamber of the MOCVD system and introduce H2 to pretreat the surface of the graphite disk. At a rate of 1°C / s, increase the temperature of the reaction chamber to 1150°C, adjust the pressure of the reaction chamber to 75torr, set the rotation speed of the graphite disk to 600 / min, control the volume flow rate of the introduced H2 to 90slm, and stop introducing H2 after 6 minutes of pretreatment reaction;

[0061] Step 2: Raise the temperature of the reaction chamber to 1250°C, adjust the pressure of the reaction chamber to 200 torr, set the rotation speed of the graphite disk to 1150 r / min, and at the same time, introduce SiH4 gas and C3H8 gas, control the volume flow rate of the introduced SiH4 to 130 sccm, and control the volume flow rate of the introduced C3H8 to 624 sccm. After reacting for 25 minutes, stop introducing SiH4 gas and C3H8 gas;

[0062] Step 3: Reduce the pressure of the reaction chamber to 80torr, introduce N2 into the reaction chamber for post-treatment reaction, control the volume flow of N2 to 100slm, and cool to 400°C at a cooling rate of 1.5°C / s, and then cool naturally to room temperature. When the repaired graphite disk in Example 7 was put into the MOCVD system and continued to be used, corrosion spots appeared after 195 cycles. The average diameter of the corrosion spots was about 0.3mm. This was because the deposition time was too short, the thickness of the SiC coating was thin, and the corrosion resistance was significantly reduced.

[0063] Example 8

[0064] Step 1: Place the graphite disk to be repaired into the reaction chamber of the MOCVD system and introduce H2 to pretreat the surface of the graphite disk. At a rate of 1°C / s, increase the temperature of the reaction chamber to 1150°C, adjust the pressure of the reaction chamber to 75torr, set the rotation speed of the graphite disk to 600 / min, control the volume flow rate of the introduced H2 to 90slm, and stop introducing H2 after 6 minutes of pretreatment reaction;

[0065] Step 2: Raise the temperature of the reaction chamber to 1250°C, adjust the pressure of the reaction chamber to 200 torr, set the rotation speed of the graphite disk to 1150 r / min, and at the same time, introduce SiH4 gas and C3H8 gas, control the volume flow rate of the introduced SiH4 to 130 sccm, and control the volume flow rate of the introduced C3H8 to 624 sccm. After reacting for 40 minutes, stop introducing SiH4 gas and C3H8 gas;

[0066] Step 3: Reduce the pressure of the reaction chamber to 80torr, introduce N2 into the reaction chamber for post-treatment reaction, control the volume flow of N2 to 100slm, and cool to 400°C at a cooling rate of 1.5°C / s, and then cool naturally to room temperature. When the repaired graphite disk in Example 8 was put into the MOCVD system and continued to be used, corrosion spots appeared after 201 cycles. The average diameter of the corrosion spots was about 0.3mm. This was because the deposition time was too long and the thickness of the SiC coating was too thick, which easily cracked during use and significantly reduced the corrosion resistance.

[0067] Comparative Example 1

[0068] Step 1: Place the graphite disk to be repaired into the reaction chamber of the MOCVD system and introduce H2 to pretreat the surface of the graphite disk. At a rate of 1°C / s, increase the temperature of the reaction chamber to 1150°C, adjust the pressure of the reaction chamber to 75torr, set the rotation speed of the graphite disk to 600 / min, control the volume flow rate of the introduced H2 to 90slm, and stop introducing H2 after 6 minutes of pretreatment reaction;

[0069] Step 2: Raise the temperature of the reaction chamber to 1250°C, adjust the pressure of the reaction chamber to 200 torr, set the rotation speed of the graphite disk to 1150 r / min, and at the same time, introduce SiH4 gas and C3H8 gas, control the volume flow rate of the introduced SiH4 to 130 sccm, and control the volume flow rate of the introduced C3H8 to 1040 sccm. After reacting for 33 minutes, stop introducing SiH4 gas and C3H8 gas;

[0070] Step 3: Reduce the pressure of the reaction chamber to 80torr, introduce N2 into the reaction chamber for post-treatment reaction, control the volume flow rate of N2 to 100slm, and cool to 400°C at a cooling rate of 1.5°C / s, and then cool naturally to room temperature. When the repaired graphite disk in Comparative Example 1 was put into the MOCVD system for continued use, corrosion spots appeared after 131 cycles. At this time, the growth source flow ratio was not in the appropriate range, resulting in incomplete forward reaction, significantly reduced production of product SiC, and failure to completely cover the surface of the graphite disk. The average diameter of the corrosion spots was about 0.8mm.

[0071] Comparative Example 2

[0072] Step 1: Place the graphite disk to be repaired into the reaction chamber of the MOCVD system and introduce H2 to pretreat the surface of the graphite disk. At a rate of 1°C / s, increase the temperature of the reaction chamber to 1150°C, adjust the pressure of the reaction chamber to 75torr, set the rotation speed of the graphite disk to 600 / min, control the volume flow rate of the introduced H2 to 90slm, and stop introducing H2 after 6 minutes of pretreatment reaction;

[0073] Step 2: Raise the temperature of the reaction chamber to 1250°C, adjust the pressure of the reaction chamber to 200 torr, set the rotation speed of the graphite disk to 1150 r / min, and at the same time, introduce SiH4 gas and C3H8 gas, control the volume flow rate of the introduced SiH4 to 130 sccm, and control the volume flow rate of the introduced C3H8 to 325 sccm. After reacting for 33 minutes, stop introducing SiH4 gas and C3H8 gas;

[0074] Step 3: Reduce the pressure of the reaction chamber to 80torr, introduce N2 into the reaction chamber for post-treatment reaction, control the volume flow rate of N2 to 100slm, and cool to 400℃ at a cooling rate of 1.5℃ / s, and then cool naturally to room temperature. When the repaired graphite disk in Comparative Example 2 was put into the MOCVD system for continued use, corrosion spots appeared after 125 cycles. At this time, the growth source flow ratio was not in the appropriate range, resulting in incomplete forward reaction, significantly reduced production of product SiC, and failure to completely cover the surface of the graphite disk. The average diameter of the corrosion spots was about 1mm.

[0075] Comparative Example 3

[0076] A commercially available graphite disk was directly put into the MOCVD system for use. Corrosion spots appeared after 183 cycles, and the average diameter of the corrosion spots was about 2.2 mm.

[0077] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for repairing SiC coating on the surface of a graphite disk using a MOCVD system, characterized in that: The following steps are involved: The graphite disk to be repaired is placed in the reaction chamber of the MOCVD system and SiH4 and C3H8 are introduced to perform a repair reaction to obtain a graphite disk with a SiC coating on the surface; The temperature of the repair reaction is 1245-1255°C; The pressure of the repair reaction is 190-210 torr; The volume flow rate of SiH4 is Q1 sccm, and the volume flow rate of C3H8 is Q2 sccm, satisfying: 3≤Q2 / Q1≤7.5; 100≤Q1≤150, 500≤Q2≤750.

2. The method according to claim 1, characterized in that The pressure of the repair reaction is 195 to 205 torr; and Satisfies: 4.6≤Q2 / Q1≤5.

0.

3. The method according to claim 2, characterized in that At least one of the following conditions is met: Condition III: 128≤Q1≤132; Condition IV: 622≤Q2≤626.

4. The method according to claim 1, characterized in that: The rotation speed of the graphite disk is denoted as Vr / min, which satisfies: 0.55≤(Q1+Q2) / V≤0.

75.

5. The method according to claim 4, characterized in that Satisfies: 0.65≤(Q1+Q2) / V≤0.

67.

6. The method according to claim 5, characterized in that The rotation speed V of the graphite disk is 1145-1155 r / min.

7. The method according to claim 1, characterized in that The graphite disk to be repaired is placed in the reaction chamber of the MOCVD system, and before SiH4 and C3H8 are introduced, the method further includes: pre-treating the surface of the graphite disk, wherein the pre-treatment is to introduce H2 into the reaction chamber for a pre-treatment reaction; The temperature of the pretreatment reaction is 1140-1160°C; The pressure of the pretreatment reaction is 74-76 torr; The rotation speed of the graphite disk is 595-605 r / min; The volume flow rate of H2 is 88-92slm; The pretreatment reaction time is 5 to 7 minutes.

8. The method according to claim 1, characterized in that: After the repair reaction is completed, N2 is introduced into the reaction chamber for post-treatment reaction, and the temperature is lowered to 400°C at a cooling rate of 1.4-1.6°C / s, and then naturally cooled to room temperature; The volume flow rate of N2 is 95-105slm; The pressure of the post-treatment reaction is 75-80 torr.

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