Control method beneficial to crystal growth of silicon carbide crystal ingot

Abstract

The invention belongs to the technical field of silicon carbide crystal ingots, and particularly relates to a control method beneficial to crystal growth of silicon carbide crystal ingots, which comprises the following specific steps: uniformly spreading silicon carbide powder serving as a silicon carbide single crystal growth raw material at the bottom of a graphite crucible; placing the silicon carbide seed crystal on the top of the graphite crucible; then, sleeving the outer side of the graphite crucible with a thermal insulation material so as to form a thermal insulation layer between the graphite crucible and a heating structure in the growth device; then, the graphite crucible is placed in a growth device and vacuumized, after the preset growth pressure is reached, the growth device can be heated, so that the silicon carbide single crystals can grow, and silicon carbide crystal ingot crystals are obtained, the silicon carbide crystal ingot crystallization method can be effectively controlled, the formation temperature control gradient of the crystal ingot is facilitated, crystallization control is facilitated, and the yield of the silicon carbide single crystals is improved. Therefore, the overall quality of the crystal ingot is improved, the crystal yield is greatly improved, and the microdefects, the basal crystal face dislocation, the screw dislocation and the stacking fault of the crystal ingot are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon carbide ingots, and in particular to a control method that is beneficial to the crystal growth of silicon carbide ingots. Background Art

[0002] Silicon carbide ingots are crystals made from silicon carbide powder by methods such as sublimation PVT. The preparation process of silicon carbide ingots includes heating silicon carbide powder in special equipment. After the temperature rises to 2200-2500℃, the powder begins to sublimate, and then crystallizes out of the ingot at the top. The growth rate of silicon carbide single crystals is slow, and usually requires continuous and stable growth for several hours to several days, which makes the cost of silicon carbide ingots high.

[0003] However, in the process of preparing silicon carbide ingots, it is difficult to control the temperature during the crystal growth process, which will lead to a large gradient temperature difference, which is not conducive to improving the quality of the ingots. Therefore, a control method is invented to facilitate the crystal growth of silicon carbide ingots. Summary of the invention

[0004] In view of the above-mentioned and / or existing problems in a control method that is beneficial to the crystal growth of silicon carbide ingots, the present invention is proposed.

[0005] Therefore, an object of the present invention is to provide a control method that is beneficial to the crystal growth of silicon carbide ingots and can solve the above-mentioned existing problems.

[0006] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0007] A control method for facilitating the crystal growth of a silicon carbide ingot comprises the following specific steps:

[0008] Step 1: Evenly spread silicon carbide powder used as raw material for growing silicon carbide single crystals on the bottom of a graphite crucible;

[0009] Step 2: placing a silicon carbide seed crystal on top of a graphite crucible;

[0010] Step 3: Covering the outer side of the graphite crucible with a heat-insulating material to form a heat-insulating layer between the graphite crucible and the heating structure in the growth device;

[0011] Step 4: placing the graphite crucible in a growth device and evacuating the device. After reaching a preset growth pressure, the growth device can be heated to allow the silicon carbide single crystal to grow and obtain a silicon carbide ingot crystallization;

[0012] The thermal insulation material is carbon fiber needle punched felt, and the shape of the carbon fiber needle punched felt is cylindrical.

[0013] As a preferred solution of the control method for facilitating the crystal growth of silicon carbide ingots described in the present invention, a protective layer is provided on the surface of the carbon fiber needle-punched felt, and the protective layer is formed by a protective coating.

[0014] As a preferred scheme of a control method for facilitating the crystal growth of silicon carbide ingots described in the present invention, the raw materials of the protective coating include, by weight, 5 to 10 parts of water, 2 to 4 parts of anti-corrosion materials, 2 to 4 parts of ablation-resistant materials, 2 to 4 parts of heat-resistant materials, and 1 to 3 parts of adhesives.

[0015] As a preferred embodiment of the control method for facilitating the crystal growth of silicon carbide ingots described in the present invention, the preparation process of the protective coating is as follows:

[0016] Process 1: Mixing water, anti-corrosion material, ablation-resistant material, temperature-resistant material and adhesive;

[0017] Process 2: Heat the mixed water, anti-corrosion material, ablation-resistant material, heat-resistant material and adhesive until the water, anti-corrosion material, ablation-resistant material, heat-resistant material and adhesive are in liquid state, thereby obtaining a protective coating.

[0018] As a preferred scheme of a control method beneficial to the crystal growth of silicon carbide ingots described in the present invention, the raw materials of the anti-corrosion material include, by weight: 4-8 parts of diatomaceous earth, 2-6 parts of high alumina cement, 1-5 parts of glass flakes, and 2-4 parts of epoxy resin.

[0019] As a preferred solution of the control method for facilitating the crystal growth of silicon carbide ingots described in the present invention, the preparation process of the anti-corrosion material is as follows:

[0020] Process 1: Stirring and mixing diatomaceous earth, high alumina cement and glass flakes;

[0021] Process 2: The epoxy resin and the mixture in process 1 are placed in a reaction kettle for mixing to obtain an anti-corrosion material.

[0022] As a preferred embodiment of the control method for facilitating the crystal growth of silicon carbide ingots described in the present invention, the raw materials of the ablation-resistant material include, by weight, 2 to 4 parts of polytetrafluoroethylene, 4 to 6 parts of polyisocyanurate foam plastic, 2 to 6 parts of polyimide, 2 to 4 parts of high silica, and 1 to 3 parts of quartz glass.

[0023] As a preferred solution of the control method for facilitating the crystal growth of silicon carbide ingots described in the present invention, the preparation process of the ablation-resistant material is as follows:

[0024] Process 1: mixing polytetrafluoroethylene, polyisocyanurate foam plastic and polyimide;

[0025] Process 2: Mixing high silica and quartz glass;

[0026] Process 3: Mix the mixtures obtained in process 1 and process 2 to obtain an ablation-resistant material.

[0027] As a preferred scheme of a control method that is beneficial to the crystal growth of silicon carbide ingots described in the present invention, the raw materials of the heat-resistant material include, by weight: 4-6 parts of silicone rubber, 2-4 parts of polyethylene, 2-6 parts of perfluoroether rubber, 1-5 parts of silicone resin, and 2-6 parts of polyphenylene sulfide.

[0028] As a preferred solution of a control method for facilitating the crystal growth of silicon carbide ingots described in the present invention, the preparation process of the temperature-resistant material is as follows:

[0029] Process 1: Mixing silicone rubber, polyethylene, perfluoroether rubber and silicone resin;

[0030] Process 2: placing polyphenylene sulfide and the mixture in process 1 in a reaction kettle for mixing to obtain a temperature-resistant material.

[0031] Compared with existing technologies:

[0032] The present invention can effectively control the silicon carbide ingot crystallization method, is beneficial to the formation temperature control gradient of the ingot, and is beneficial to crystallization control, thereby improving the overall quality of the ingot and greatly improving the crystal yield, and its microscopic defects, basal plane dislocations, screw dislocations, and stacking faults are improved and enhanced; in addition, by arranging a protective layer on the outer surface of the carbon fiber needle felt, the service life of the thermal insulation material can be increased. DETAILED DESCRIPTION

[0033] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below.

[0034] Embodiment 1:

[0035] The present invention provides a control method for facilitating the crystal growth of a silicon carbide ingot, comprising the following specific steps:

[0036] Step 1: Evenly spread silicon carbide powder used as raw material for growing silicon carbide single crystals on the bottom of a graphite crucible;

[0037] Step 2: placing a silicon carbide seed crystal on top of a graphite crucible;

[0038] Step 3: Covering the outer side of the graphite crucible with a heat-insulating material to form a heat-insulating layer between the graphite crucible and the heating structure in the growth device;

[0039] Step 4: placing the graphite crucible in a growth device and evacuating the device. After reaching a preset growth pressure, the growth device can be heated to allow the silicon carbide single crystal to grow and obtain a silicon carbide ingot crystallization;

[0040] The thermal insulation material is set to be carbon fiber needle felt, and the shape of the carbon fiber needle felt is set to be cylindrical; among them, the carbon fiber needle felt is a soft felt made of carbon fiber through a needle punching process and then graphitized; it has the characteristics of smooth surface, no hair loss, high temperature resistance, low density, high purity, low thermal conductivity, etc.; the carbon fiber needle felt has firm fiber bonding, is resistant to air flow erosion, not easy to pulverize, has strong self-support, uniform density, good thermal insulation performance, and low heat capacity, etc.

[0041] The surface of the carbon fiber needle felt is provided with a protective layer, which is formed by a protective coating.

[0042] The raw materials of the protective coating include, by weight: 5 parts of water, 2 parts of anti-corrosion materials, 2 parts of ablation-resistant materials, 2 parts of heat-resistant materials, and 1 part of adhesive.

[0043] The preparation process of protective coating is as follows:

[0044] Process 1: Mixing water, anti-corrosion material, ablation-resistant material, temperature-resistant material and adhesive;

[0045] Process 2: Heat the mixed water, anti-corrosion material, ablation-resistant material, heat-resistant material and adhesive until the water, anti-corrosion material, ablation-resistant material, heat-resistant material and adhesive are in liquid state, thereby obtaining a protective coating.

[0046] The raw materials of the anti-corrosion material include, by weight: 4 parts of diatomaceous earth, 2 parts of high-alumina cement, 1 part of glass flakes, and 2 parts of epoxy resin.

[0047] The preparation process of anti-corrosion materials is as follows:

[0048] Process 1: Stirring and mixing diatomaceous earth, high alumina cement and glass flakes;

[0049] Process 2: The epoxy resin and the mixture in process 1 are placed in a reaction kettle for mixing to obtain an anti-corrosion material.

[0050] The raw materials of the ablation-resistant material include, by weight: 2 parts of polytetrafluoroethylene, 4 parts of polyisocyanurate foam plastics, 2 parts of polyimide, 2 parts of high silica, and 1 part of quartz glass.

[0051] The preparation process of ablation-resistant materials is as follows:

[0052] Process 1: mixing polytetrafluoroethylene, polyisocyanurate foam plastic and polyimide;

[0053] Process 2: Mixing high silica and quartz glass;

[0054] Process 3: Mix the mixtures obtained in process 1 and process 2 to obtain an ablation-resistant material.

[0055] The raw materials of the heat-resistant material include, by weight: 4 parts of silicone rubber, 2 parts of polyethylene, 2 parts of perfluoroether rubber, 1 part of organic silicone resin, and 2 parts of polyphenylene sulfide.

[0056] The preparation process of temperature-resistant materials is as follows:

[0057] Process 1: Mixing silicone rubber, polyethylene, perfluoroether rubber and silicone resin;

[0058] Process 2: placing polyphenylene sulfide and the mixture in process 1 in a reaction kettle for mixing to obtain a temperature-resistant material.

[0059] Embodiment 2:

[0060] The present invention provides a control method for facilitating the crystal growth of a silicon carbide ingot, comprising the following specific steps:

[0061] Step 1: Evenly spread silicon carbide powder used as raw material for growing silicon carbide single crystals on the bottom of a graphite crucible;

[0062] Step 2: placing a silicon carbide seed crystal on top of a graphite crucible;

[0063] Step 3: Covering the outer side of the graphite crucible with a heat-insulating material to form a heat-insulating layer between the graphite crucible and the heating structure in the growth device;

[0064] Step 4: placing the graphite crucible in a growth device and evacuating the device. After reaching a preset growth pressure, the growth device can be heated to allow the silicon carbide single crystal to grow and obtain a silicon carbide ingot crystallization;

[0065] The thermal insulation material is set to be carbon fiber needle felt, and the shape of the carbon fiber needle felt is set to be cylindrical; among them, the carbon fiber needle felt is a soft felt made of carbon fiber through a needle punching process and then graphitized; it has the characteristics of smooth surface, no hair loss, high temperature resistance, low density, high purity, low thermal conductivity, etc.; the carbon fiber needle felt has firm fiber bonding, is resistant to air flow erosion, not easy to pulverize, has strong self-support, uniform density, good thermal insulation performance, and low heat capacity, etc.

[0066] The surface of the carbon fiber needle felt is provided with a protective layer, which is formed by a protective coating.

[0067] The raw materials of the protective coating include, by weight: 7.5 parts of water, 3 parts of anti-corrosion material, 3 parts of ablation-resistant material, 3 parts of heat-resistant material, and 2 parts of adhesive.

[0068] The preparation process of protective coating is as follows:

[0069] Process 1: Mixing water, anti-corrosion material, ablation-resistant material, temperature-resistant material and adhesive;

[0070] Process 2: Heat the mixed water, anti-corrosion material, ablation-resistant material, heat-resistant material and adhesive until the water, anti-corrosion material, ablation-resistant material, heat-resistant material and adhesive are in liquid state, thereby obtaining a protective coating.

[0071] The raw materials of the anti-corrosion material include, by weight: 6 parts of diatomaceous earth, 4 parts of high-alumina cement, 3 parts of glass flakes, and 3 parts of epoxy resin.

[0072] The preparation process of anti-corrosion materials is as follows:

[0073] Process 1: Stirring and mixing diatomaceous earth, high alumina cement and glass flakes;

[0074] Process 2: The epoxy resin and the mixture in process 1 are placed in a reaction kettle for mixing to obtain an anti-corrosion material.

[0075] The raw materials of the ablation-resistant material include, by weight: 3 parts of polytetrafluoroethylene, 5 parts of polyisocyanurate foam plastics, 4 parts of polyimide, 3 parts of high silica, and 2 parts of quartz glass.

[0076] The preparation process of ablation-resistant materials is as follows:

[0077] Process 1: mixing polytetrafluoroethylene, polyisocyanurate foam plastic and polyimide;

[0078] Process 2: Mixing high silica and quartz glass;

[0079] Process 3: Mix the mixtures obtained in process 1 and process 2 to obtain an ablation-resistant material.

[0080] The raw materials of the heat-resistant material include, by weight: 5 parts of silicone rubber, 3 parts of polyethylene, 4 parts of perfluoroether rubber, 3 parts of organic silicone resin, and 4 parts of polyphenylene sulfide.

[0081] The preparation process of temperature-resistant materials is as follows:

[0082] Process 1: Mixing silicone rubber, polyethylene, perfluoroether rubber and silicone resin;

[0083] Process 2: placing polyphenylene sulfide and the mixture in process 1 in a reaction kettle for mixing to obtain a temperature-resistant material.

[0084] Embodiment 3:

[0085] The present invention provides a control method for facilitating the crystal growth of a silicon carbide ingot, comprising the following specific steps:

[0086] Step 1: Evenly spread silicon carbide powder used as raw material for growing silicon carbide single crystals on the bottom of a graphite crucible;

[0087] Step 2: placing a silicon carbide seed crystal on top of a graphite crucible;

[0088] Step 3: Covering the outer side of the graphite crucible with a heat-insulating material to form a heat-insulating layer between the graphite crucible and the heating structure in the growth device;

[0089] Step 4: placing the graphite crucible in a growth device and evacuating the device. After reaching a preset growth pressure, the growth device can be heated to allow the silicon carbide single crystal to grow and obtain a silicon carbide ingot crystallization;

[0090] The thermal insulation material is set to be carbon fiber needle felt, and the shape of the carbon fiber needle felt is set to be cylindrical; among them, the carbon fiber needle felt is a soft felt made of carbon fiber through a needle punching process and then graphitized; it has the characteristics of smooth surface, no hair loss, high temperature resistance, low density, high purity, low thermal conductivity, etc.; the carbon fiber needle felt has firm fiber bonding, is resistant to air flow erosion, not easy to pulverize, has strong self-support, uniform density, good thermal insulation performance, and low heat capacity, etc.

[0091] The surface of the carbon fiber needle felt is provided with a protective layer, which is formed by a protective coating.

[0092] The raw materials of the protective coating include, by weight: 10 parts of water, 4 parts of anti-corrosion material, 4 parts of ablation-resistant material, 4 parts of heat-resistant material, and 3 parts of adhesive.

[0093] The preparation process of protective coating is as follows:

[0094] Process 1: Mixing water, anti-corrosion material, ablation-resistant material, temperature-resistant material and adhesive;

[0095] Process 2: Heat the mixed water, anti-corrosion material, ablation-resistant material, heat-resistant material and adhesive until the water, anti-corrosion material, ablation-resistant material, heat-resistant material and adhesive are in liquid state, thereby obtaining a protective coating.

[0096] The raw materials of the anti-corrosion material include, by weight: 8 parts of diatomaceous earth, 6 parts of high-alumina cement, 5 parts of glass flakes, and 4 parts of epoxy resin.

[0097] The preparation process of anti-corrosion materials is as follows:

[0098] Process 1: Stirring and mixing diatomaceous earth, high alumina cement and glass flakes;

[0099] Process 2: The epoxy resin and the mixture in process 1 are placed in a reaction kettle for mixing to obtain an anti-corrosion material.

[0100] The raw materials of the ablation-resistant material include, by weight: 4 parts of polytetrafluoroethylene, 6 parts of polyisocyanurate foam plastics, 6 parts of polyimide, 4 parts of high silica, and 3 parts of quartz glass.

[0101] The preparation process of ablation-resistant materials is as follows:

[0102] Process 1: mixing polytetrafluoroethylene, polyisocyanurate foam plastic and polyimide;

[0103] Process 2: Mixing high silica and quartz glass;

[0104] Process 3: Mix the mixtures obtained in process 1 and process 2 to obtain an ablation-resistant material.

[0105] The raw materials of the heat-resistant material include, by weight: 6 parts of silicone rubber, 4 parts of polyethylene, 6 parts of perfluoroether rubber, 5 parts of silicone resin, and 6 parts of polyphenylene sulfide.

[0106] The preparation process of temperature-resistant materials is as follows:

[0107] Process 1: Mixing silicone rubber, polyethylene, perfluoroether rubber and silicone resin;

[0108] Process 2: placing polyphenylene sulfide and the mixture in process 1 in a reaction kettle for mixing to obtain a temperature-resistant material.

[0109] The thermal insulation materials prepared in the above examples 1-3 are compared to obtain the following data:

[0110] Example 1 Example 2 Example 3 Corrosion resistance grade Sa2 Sa2.5 Sa2 Ablation resistance excellent excellent excellent Temperature resistance level 2043℃ 2319℃ 2172℃

[0111] It can be seen from the above table that the thermal insulation materials prepared in Examples 1-3 have good performance in terms of corrosion resistance, ablation resistance and temperature resistance. After use, Example 2 has the best effect.

[0112] Although the present invention has been described above with reference to the embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the various features in the embodiments disclosed in the present invention may be used in combination with each other in any manner, and the fact that these combinations are not exhaustively described in this specification is only for the sake of omitting space and saving resources. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A control method for facilitating the crystal growth of a silicon carbide ingot, characterized in that: The specific steps are as follows: Step 1: Evenly spread silicon carbide powder used as raw material for growing silicon carbide single crystals on the bottom of a graphite crucible; Step 2: placing a silicon carbide seed crystal on top of a graphite crucible; Step 3: Covering the outer side of the graphite crucible with a heat-insulating material to form a heat-insulating layer between the graphite crucible and the heating structure in the growth device; Step 4: placing the graphite crucible in a growth device and evacuating the device. After reaching a preset growth pressure, the growth device can be heated to allow the silicon carbide single crystal to grow and obtain a silicon carbide ingot crystallization; The thermal insulation material is carbon fiber needle punched felt, and the shape of the carbon fiber needle punched felt is cylindrical.

2. A control method for facilitating the crystal growth of silicon carbide ingots according to claim 1, characterized in that: A protective layer is provided on the surface of the carbon fiber needle-punched felt, and the protective layer is formed by a protective coating.

3. A control method for facilitating the crystal growth of silicon carbide ingots according to claim 2, characterized in that: The raw materials of the protective coating include, by weight: 5-10 parts of water, 2-4 parts of anti-corrosion materials, 2-4 parts of ablation-resistant materials, 2-4 parts of heat-resistant materials, and 1-3 parts of adhesives.

4. A control method for facilitating the crystal growth of silicon carbide ingots according to claim 3, characterized in that: The preparation process of the protective coating is as follows: Process 1: Mixing water, anti-corrosion material, ablation-resistant material, temperature-resistant material and adhesive; Process 2: Heat the mixed water, anti-corrosion material, ablation-resistant material, heat-resistant material and adhesive until the water, anti-corrosion material, ablation-resistant material, heat-resistant material and adhesive are in liquid state, so as to obtain the protective coating.

5. The control method for facilitating the crystal growth of silicon carbide ingot according to claim 3, characterized in that: The raw materials of the anti-corrosion material include, by weight: 4-8 parts of diatomaceous earth, 2-6 parts of high-alumina cement, 1-5 parts of glass flakes, and 2-4 parts of epoxy resin.

6. A control method for facilitating the crystal growth of silicon carbide ingots according to claim 5, characterized in that: The preparation process of the anti-corrosion material is as follows: Process 1: Stirring and mixing diatomaceous earth, high alumina cement and glass flakes; Process 2: The epoxy resin and the mixture in process 1 are placed in a reaction kettle for mixing to obtain an anti-corrosion material.

7. A control method for facilitating the crystal growth of silicon carbide ingots according to claim 3, characterized in that: The raw materials of the ablation-resistant material include, by weight: 2-4 parts of polytetrafluoroethylene, 4-6 parts of polyisocyanurate foam plastics, 2-6 parts of polyimide, 2-4 parts of high silica, and 1-3 parts of quartz glass.

8. A control method for facilitating the crystal growth of silicon carbide ingots according to claim 7, characterized in that: The preparation process of the ablation-resistant material is as follows: Process 1: mixing polytetrafluoroethylene, polyisocyanurate foam plastic and polyimide; Process 2: Mixing high silica and quartz glass; Process 3: Mix the mixtures obtained in process 1 and process 2 to obtain an ablation-resistant material.

9. The control method for facilitating the crystal growth of silicon carbide ingot according to claim 3, characterized in that: The raw materials of the heat-resistant material include, by weight: 4-6 parts of silicone rubber, 2-4 parts of polyethylene, 2-6 parts of perfluoroether rubber, 1-5 parts of organic silicone resin, and 2-6 parts of polyphenylene sulfide.

10. A control method for facilitating the crystal growth of silicon carbide ingots according to claim 9, characterized in that: The preparation process of the heat-resistant material is as follows: Process 1: Mixing silicone rubber, polyethylene, perfluoroether rubber and silicone resin; Process 2: placing polyphenylene sulfide and the mixture in process 1 in a reaction kettle for mixing to obtain a temperature-resistant material.