A method for repairing a graphite disk

Abstract

The present invention relates to the technical field of epitaxial wafer growth equipment, and in particular to a method for repairing a graphite disk. The method for repairing a graphite disk comprises the following steps: cleaning the damaged part of the graphite disk and then digging a hole to obtain a columnar hole, cleaning the hole and cutting a silicon nitride (SiN) material into a repair block with the same shape as the hole, placing the repair block into the hole and injecting a sintering aid, and sintering at 1000-2000°C for 12-15h. The method uses a silicon nitride repair block to repair a graphite disk, which greatly reduces the cost without affecting the performance of the graphite disk, and compared with conventional graphite repair, the graphite disk repaired by the method of the present invention has better durability and higher oxidation resistance temperature.

Description

Technical Field

[0001] The invention relates to the technical field of epitaxial wafer growth equipment, and in particular to a method for repairing a graphite disk. Background Art

[0002] Graphite disc is an indispensable consumable part in MOCVD epitaxial growth reaction equipment. The quality of graphite disc has a very critical impact on ensuring the quality and consistency of LED chips. The graphite disc currently used is mainly Si-coated stone grinding disc, which has the characteristics of high temperature resistance, oxidation resistance, high purity, acid, alkali, salt and organic reagent resistance. Compared with Si-coated stone grinding disc, Si-free stone grinding disc begins to oxidize strongly at 400℃. Even if the temperature is not high, it will lose powder due to oxidation after long-term use, and will adhere to the workpiece and table, polluting the use environment; while SiC (silicon carbide) coated stone grinding disc still has very good oxidation resistance at temperatures as high as 1600℃, stable physical and chemical properties, and SiC coated graphite base has the characteristics of erosion resistance, high hardness, dense surface, fine particles, etc. These characteristics also make Si-coated stone grinding disc widely used.

[0003] During the MOCVD deposition process, the SiC-coated graphite disk used as the carrier of MOCVD epitaxial growth wafers often breaks due to the continuous generation of extreme temperature conditions and uneven temperature during the process. After the graphite disk coating is broken, the gas enters the graphite disk body and forms holes.

[0004] The existing method of repairing graphite discs is to use graphite blocks to fill and trim the hollow positions. For example, the Chinese invention patent with publication number CN110890309A discloses a method for repairing graphite discs. The repair method includes the following steps: clearing the wormholes on the scrapped graphite disc to determine the damage range; machining a recessed portion that covers the damage range on the scrapped graphite disc through mechanical processing; using a graphite repair block made of graphite blocks to fill the recessed portion accordingly, and after the filling is completed, further processing and trimming it to make it a part of the scrapped graphite disc; brazing with pure silicon solder to join the graphite repair block and the scrapped graphite disc, and reacting and growing silicon carbide on the surface of the graphite repair block, which is combined with the original silicon carbide coating of the scrapped graphite disc to complete the repair, so that the scrapped graphite disc can be used again. However, this method is more complicated and costly. Summary of the invention

[0005] In order to overcome the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a method for repairing a graphite disk which is simple to operate and has lower cost.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for repairing a graphite disk, comprising the following steps: cleaning the damaged part of the graphite disk and then digging a hole to obtain a columnar hole, cleaning the hole and cutting the silicon nitride (SiN) material into a repair block with the same shape as the hole, placing the repair block into the hole and injecting a sintering aid, and sintering at 1000~2000℃ for 12~15h.

[0007] The beneficial effect of the present invention is that it provides a method for repairing a graphite disk, after cleaning the damaged part and determining the damaged range, a repair block having the same shape as the hole is formed by mechanical processing using silicon nitride material, the hole is filled and sintered, and the repair block and the graphite disk are joined. Silicon nitride, as an advanced refractory material, has good thermal shock resistance and extremely high mechanical strength, greatly reduces the cost without affecting the performance of the graphite disk, and compared with conventional graphite repair, the graphite disk repaired by the method of the present invention has better durability and higher oxidation resistance temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 Shown is a schematic diagram of a graphite disk repair according to a specific embodiment of the present invention;

[0009] Figure 2 Shown is the process flow of repairing a graphite disk according to a specific embodiment of the present invention;

[0010] Figure 3 Shown is a comparison chart of the durability and anti-oxidation temperature of the repaired graphite disks of Example 1 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0011] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in combination with the implementation modes and the accompanying drawings.

[0012] The most critical concept of the present invention is to use silicon nitride repair blocks to repair graphite disks, thereby greatly reducing costs without affecting the performance of the graphite disks.

[0013] Please refer to Figure 1 to Figure 2 As shown, a method for repairing a graphite disk of the present invention comprises the following steps: cleaning the damaged part of the graphite disk and then digging a hole to obtain a columnar hole, cleaning the hole and cutting the silicon nitride material into a repair block with the same shape as the hole, placing the repair block into the hole and injecting a sintering aid, and sintering at 1000-2000°C for 12-15h.

[0014] From the above description, it can be seen that the beneficial effect of the present invention is that after cleaning the damaged area and determining the scope of damage, a repair block with the same shape as the hole is formed by machining using silicon nitride material, the hole is filled and densified by sintering, and the repair block and the graphite disk are joined.

[0015] Silicon nitride is not only a high-temperature insulating material with good heat shock resistance, but also has high mechanical strength at high temperatures. Sintered silicon nitride has excellent thermal shock resistance and can continue to be used in continuous high and low temperature thermal cycle tests. Using silicon nitride to repair graphite disks can greatly reduce costs without affecting the properties of the graphite disks. Compared with conventional graphite repairs, the graphite disks repaired using the method of the present invention have better durability and higher oxidation resistance temperature.

[0016] Furthermore, the cleaning is specifically as follows: wiping with industrial alcohol having a volume fraction of 99.99% and a fiber dust-free cloth, and then purging with nitrogen.

[0017] From the above description, it can be seen that there are two cleanings. The first cleaning removes impurities (mainly Ga and graphite powder) at the damaged part to determine the scope of damage; the second cleaning removes impurities inside the holes (produced by digging holes) to facilitate subsequent sintering.

[0018] Furthermore, the distance between two adjacent damaged areas is greater than 3 mm.

[0019] Furthermore, the repair block needs to be polished until there are no protrusions on the surface.

[0020] From the above description, it can be seen that grinding the repair block until there is no protrusion on the surface is conducive to uniform injection of the sintering aid.

[0021] Furthermore, the gap between the repair block and the hole is ≤0.05 mm.

[0022] Preferably, the gap between the repair block and the hole is 0.01 mm.

[0023] From the above description, it can be seen that the repair block needs to fit the hole as closely as possible within the process range, but a gap that is too small is not conducive to the injection of the sintering aid.

[0024] Furthermore, the sintering aid includes pure silicon powder and silicon nitride powder in a mass ratio of 1:1, and the sintering aid fills the gap between the repair block and the hole.

[0025] Furthermore, the sintering temperature is 1200-1400°C.

[0026] From the above description, it can be seen that the load of sintered silicon nitride at a high temperature of 1200~1400℃ is 34MPa, and the deformation is small over a long period of time, and the repair position will not be deformed and damaged at high temperature.

[0027] Furthermore, after sintering, the residual material needs to be scraped off and the graphite disk needs to be polished until there is no protrusion on the surface of the repaired part.

[0028] From the above description, it can be known that the graphite disk surface protrusions are prevented from affecting the growth of the epitaxial wafer.

[0029] Please refer to Figure 1 to Figure 2 As shown, the first embodiment of the present invention is: a method for repairing a graphite disk, comprising the following steps:

[0030] S1. Clean the damaged part of the graphite disk: first use 99.99% industrial alcohol and fiber dust-free cloth to wipe the damaged part of the graphite disk, then use a nitrogen air gun to purge it to remove impurities (mainly Ga and graphite powder) in the damaged part and determine the damaged range; the distance between two adjacent damaged parts is greater than 11mm;

[0031] S2: Through machine tool processing, select a drill bit with a diameter of 10mm (matching the damaged part) to drill and dig a hole with a diameter of 10mm;

[0032] S3: After digging the hole, wipe the hole again with 99.99% industrial alcohol and fiber dust-free cloth, and then use a nitrogen air gun to purge it to remove impurities generated by digging inside the hole;

[0033] S4: Use a cutting machine to cut the silicon nitride material into a suitable size, machine and grind it until there is no protrusion on the surface, and grind the silicon nitride material into a repair block that meets the size of the hole to fill the hole; the gap between the repair block and the hole is 0.01mm;

[0034] S5: injecting a sintering agent into the gap of the filled hole, and placing the graphite disk injected with the sintering agent into a high temperature oven at 1300°C for 13h, so that the repair block is bonded to the graphite disk;

[0035] S6: Use a spatula to scrape off the residual material on the surface of the baked graphite disc, and use sandpaper or a grinding wheel to grind it to remove the residual material and other excess parts until there is no protrusion on the surface of the repaired graphite disc.

[0036] The sintering aid comprises pure silicon powder and silicon nitride powder in a mass ratio of 1:1.

[0037] Embodiment 2 of the present invention is: a method for repairing a graphite disk, comprising the following steps:

[0038] S1. Clean the damaged part of the graphite disk: first use 99.99% industrial alcohol and fiber dust-free cloth to wipe the damaged part of the graphite disk, then use a nitrogen air gun to purge it to remove impurities (mainly Ga and graphite powder) in the damaged part and determine the damaged range; the distance between two adjacent damaged parts is greater than 4mm;

[0039] S2: Through machine tool processing, a drill bit with a diameter of 3 mm (matching the damaged part) is selected to drill and dig holes at the damaged part to dig out holes with a diameter of 3 mm;

[0040] S3: After digging the hole, wipe the hole again with 99.99% industrial alcohol and fiber dust-free cloth, and then use a nitrogen air gun to purge it to remove impurities generated by digging inside the hole;

[0041] S4: Use a cutting machine to cut the silicon nitride material into a suitable size, machine and grind it until there is no protrusion on the surface, and grind the silicon nitride material into a repair block that meets the size of the hole to fill the hole; the gap between the repair block and the hole is 0.05mm;

[0042] S5: injecting a sintering agent into the gap of the filled hole, and placing the graphite disk injected with the sintering agent into a high temperature oven at 1000°C for 15h, so that the repair block is bonded to the graphite disk;

[0043] S6: Use a spatula to scrape off the residual material on the surface of the baked graphite disc, and use sandpaper or a grinding wheel to grind it to remove the residual material and other excess parts until there is no protrusion on the surface of the repaired graphite disc.

[0044] The sintering aid comprises pure silicon powder and silicon nitride powder in a mass ratio of 1:1.

[0045] Embodiment 3 of the present invention is: a method for repairing a graphite disk, comprising the following steps:

[0046] S1. Clean the damaged part of the graphite disk: first use 99.99% industrial alcohol and fiber dust-free cloth to wipe the damaged part of the graphite disk, then use a nitrogen air gun to purge it to remove impurities (mainly Ga and graphite powder) in the damaged part and determine the damaged range; the distance between two adjacent damaged parts is greater than 17mm;

[0047] S2: Through machine tool processing, a drill bit with a diameter of 15 mm (matching the damaged part) is selected to drill and dig holes at the damaged part to dig out holes with a diameter of 15 mm;

[0048] S3: After digging the hole, wipe the hole again with 99.99% industrial alcohol and fiber dust-free cloth, and then use a nitrogen air gun to purge it to remove impurities generated by digging inside the hole;

[0049] S4: Use a cutting machine to cut the silicon nitride material into a suitable size, machine and grind it until there is no protrusion on the surface, and grind the silicon nitride material into a repair block that meets the size of the hole to fill the hole; the gap between the repair block and the hole is 0.001mm;

[0050] S5: injecting a sintering agent into the gap of the filled hole, and placing the graphite disk injected with the sintering agent into a high temperature oven at 2000°C for 15h, so that the repair block is bonded to the graphite disk;

[0051] S6: Use a spatula to scrape off the residual material on the surface of the baked graphite disc, and use sandpaper or a grinding wheel to grind it to remove the residual material and other excess parts until there is no protrusion on the surface of the repaired graphite disc.

[0052] The sintering aid comprises pure silicon powder and silicon nitride powder in a mass ratio of 1:1.

[0053] Comparative Example 1 of the present invention is: using graphite to repair holes, comprising the following steps:

[0054] S1. Clean the damaged part of the graphite disk: first use 99.99% industrial alcohol and a fiber dust-free cloth to wipe the damaged part of the graphite disk, then use a nitrogen air gun to purge it to remove impurities (mainly Ga and graphite powder) at the damaged part and determine the damaged range;

[0055] S2: Through machine tool processing, a drill bit with a diameter of 15 mm (matching the damaged part) is selected to drill and dig holes at the damaged part to dig out holes with a diameter of 15 mm;

[0056] S3: After digging the hole, wipe the hole again with 99.99% industrial alcohol and fiber dust-free cloth, and then use a nitrogen air gun to purge it to remove impurities generated by digging inside the hole;

[0057] S4: Use a cutting machine to cut the graphite material into appropriate sizes, machine and grind it until there are no protrusions on the surface, and grind the graphite material into repair blocks that match the size of the holes to fill the holes.

[0058] 1. The repair methods of Example 1 and Comparative Example 1 were used to repair multiple graphite holes with a diameter of 9 mm. The cost of raw materials in Example 1 was 1100 to 1400 yuan, and the cost of raw materials in Comparative Example 1 was about 2000 yuan. Therefore, the repair method of the present invention can effectively reduce the cost of raw materials.

[0059] 2. Use the repairing methods of Example 1 and Comparative Example 1 to repair multiple graphite holes with a diameter of 9 mm, and perform durability and oxidation resistance temperature tests on the repaired graphite disks. The test results (average values) are shown in Figure 3 .Depend on Figure 3 It can be seen that the graphite disk repaired by the method of Example 1 has better durability and higher oxidation resistance temperature.

[0060] In summary, the method for repairing a graphite disk provided by the present invention, after cleaning the damaged part and determining the damage range, uses silicon nitride material to form a repair block with the same shape as the hole through mechanical processing, fills the hole and densifies it through sintering, so that the repair block and the graphite disk are joined.

[0061] Silicon nitride is not only a high-temperature insulating material with good heat shock resistance, but also has high mechanical strength at high temperatures. Sintered silicon nitride has excellent thermal shock resistance and can continue to be used in continuous high and low temperature thermal cycle tests. Using silicon nitride to repair graphite disks can greatly reduce costs without affecting the properties of the graphite disks. Compared with conventional graphite repairs, the graphite disks repaired using the method of the present invention have better durability and higher oxidation resistance temperature.

[0062] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for repairing a graphite disk, characterized in that: The method comprises the following steps: cleaning the damaged part of the graphite disk and then digging a hole to obtain a columnar hole, cleaning the hole and cutting the silicon nitride material into a repair block with the same shape as the hole, placing the repair block into the hole and filling the gap between the repair block and the hole with pure silicon powder and silicon nitride powder in a mass ratio of 1:1, and sintering at 1000-2000°C for 12-15 hours.

2. The method for repairing a graphite disk according to claim 1, characterized in that: The cleaning is specifically as follows: wiping with industrial alcohol having a volume fraction of 99.99% and a fiber dust-free cloth, and then purging with nitrogen.

3. The method for repairing a graphite disk according to claim 1, characterized in that: The distance between two adjacent damaged parts is greater than 3 mm.

4. The method for repairing a graphite disk according to claim 1, characterized in that: The repair block needs to be polished until there is no protrusion on the surface.

5. The method for repairing a graphite disk according to claim 1, characterized in that: The gap between the repair block and the hole is ≤0.05mm.

6. The method for repairing a graphite disk according to claim 1, characterized in that: The sintering temperature is 1200-1400°C.

7. The method for repairing a graphite disk according to claim 1, characterized in that: After sintering, the residual material needs to be scraped off and the graphite disk needs to be polished until there is no protrusion on the surface of the repaired area.

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