CN111717918A - Rapid synthesis method of high-purity SiC powder - Google Patents
Rapid synthesis method of high-purity SiC powder Download PDFInfo
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- CN111717918A CN111717918A CN201910207141.3A CN201910207141A CN111717918A CN 111717918 A CN111717918 A CN 111717918A CN 201910207141 A CN201910207141 A CN 201910207141A CN 111717918 A CN111717918 A CN 111717918A
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/90—Carbides
- C01B32/914—Carbides of single elements
- C01B32/956—Silicon carbide
- C01B32/963—Preparation from compounds containing silicon
- C01B32/984—Preparation from elemental silicon
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B35/00—Apparatus not otherwise provided for, specially adapted for the growth, production or after-treatment of single crystals or of a homogeneous polycrystalline material with defined structure
- C30B35/007—Apparatus for preparing, pre-treating the source material to be used for crystal growth
Abstract
The invention relates to a rapid synthesis method of high-purity SiC powder, belonging to the technical field of silicon carbide powder synthesis and comprising the following steps: selecting high-purity C powder and uniformly mixing with Si powder; selecting high-purity polycarbosilane powder and uniformly mixing the high-purity polycarbosilane powder with the mixed carbon silicon powder; putting the mixed powder into a high-purity graphite crucible, putting the crucible into a medium-frequency induction heating furnace, and vacuumizing; filling inert gas and slowly heating; introducing high-purity argon or a mixture of the argon and hydrogen into the chamber, and heating to perform synthetic reaction; filling high-purity argon and hydrogen into the chamber, pressurizing, rapidly heating to perform synthetic conversion reaction, and slowly cooling to room temperature under the protection of argon and hydrogen. Can meet the growth requirement of high-purity semi-insulating SiC single crystals, is simple to operate, is suitable for rapid mass production, and further reduces the impurity concentration.
Description
Technical Field
The invention relates to a rapid synthesis method of high-purity SiC powder for semiconductor single crystal growth, belonging to the technical field of silicon carbide powder synthesis.
Background
Silicon carbide (SiC) is an important member of third-generation wide band gap semiconductor materials (also called high-temperature semiconductor materials), has large forbidden band width, high thermal conductivity, high carrier saturation migration speed, high critical breakdown electric field strength and excellent chemical stability, and can be applied to manufactured devices under harsh conditions of high temperature, high frequency, high power, high voltage, strong radiation and the like. At present, the material has wide application in the fields of white light illumination, aerospace, nuclear reactor systems, radar communication, petroleum drilling, automotive electronics, equipment and the like.
The growth of high quality SiC single crystals relies on high purity SiC powders. At present, the synthesis method of SiC powder mainly comprises three methods: the Acheson process, the organic synthesis process and the high temperature self-propagating process. The Acheson process (also known as carbothermic process) is currently the predominant method for the industrial production of SiC powders using SiO in an inert atmosphere (typically Ar gas)2The SiC is produced by chemical reaction with C at high temperature, and the raw material in actual production is quartz sand (the main component is SiO)2) And coke (main component C). In order to make the CO product smoothly escape, a certain amount of sawdust and salt are added into the raw materials. Because of the limited purity of the starting material, the SiC produced by this process usually contains a high level of impurities, which require acid and alkali washing to improve purity. The organic synthesis methods mainly comprise two methods, one is Silane (SiH)4) And acetylene (C)2H4) The other organic synthesis method is to calcine high-purity tetraethoxysilane (a high-purity silicon source) and (linear) novolac type phenol resin (a high-purity carbon source) at about 1700 ℃ to obtain the high-purity SiC powder with the granularity of 10-500 mu m and the impurity content of less than 1 ppm. The two methods have higher requirements on reaction equipment and raw material pretreatment, and are not applied in large scale at present. The high-temperature self-propagating synthesis method has become the preferred method for synthesizing high-purity powder at home and abroad at present. The method utilizes the self-conduction function of the reaction heat of the substances to cause chemical reaction between the substances and form high-temperature synthesis reaction of the compound in a very short time. The basic principle of the method is as follows: heating the uniformly mixed Si powder and C powder in a reaction furnace, heating under the protection of inert atmosphere until the Si is molten, dissolving the C in the Si liquid, increasing the ignition contact area and the diffusion speed, and when the first layer is formedWhen the temperature of the reaction kettle is increased to the ignition temperature, the Si and the C instantaneously react to release heat, the peripheral reaction is ignited layer by layer, more Si is promoted to be molten, the C is continuously dissolved, and the reaction is continuously carried out.
Chinese patent document CN1163895A provides a process for directly generating high-purity α -SiC micropowder, which comprises mixing quartz powder, activated carbon, composite catalyst and organic binder according to a certain proportion, granulating the base material, drying, loading into a pot and charging into a furnace to obtain α -SiC micropowder grade product with higher purity and average particle size less than 1um, and patent CN 102674357A provides a method for synthesizing high-purity silicon carbide raw material for silicon carbide single crystal growth, wherein high-purity Si powder and high-purity C powder are placed into a crucible, then placed into a heating furnace, and the growth chamber of the heating furnace is pumped to high vacuum to 1 × 10-3Pa below while raising the temperature to 600-1300 ℃; keeping the reaction for 2-20 hours at the reaction temperature of 1500-2500 ℃ in a high-purity non-oxidizing atmosphere with specified pressure, and then cooling to room temperature to obtain the high-purity silicon carbide raw material for growing the silicon carbide single crystal. Patent CN 103708463A discloses a preparation method of kilogram-grade high-purity silicon carbide powder, which comprises the steps of firstly plating a carbon film on a graphite crucible, then plating silicon carbide on the graphite crucible plated with the carbon film, putting the mixed C powder and Si powder into a medium-frequency induction heating furnace, pumping air to a system, heating to a synthesis temperature under the protection of inert gas, preserving heat for a certain time, and then cooling to obtain the kilogram-grade high-purity silicon carbide powder. The patent CN100595144C provides a method for obtaining high-purity silicon carbide powder by a secondary synthesis method, the method is that a graphite crucible filled with mixed high-purity silicon carbide powder is placed in an induction heating furnace, the product obtained after the reaction is heated to 1500 ℃ under the protection of inert gas is ground into powder with the diameter less than 1mm, and the powder is uniformly mixed and then heated to 1600-2000 ℃ to be synthesized for 2-10 hours to obtain the high-purity silicon carbide powder suitable for the growth of semiconductor single crystals. Patent CN103508454B discloses a preparation method for obtaining high-purity silicon carbide raw material by three-time synthesis. The method comprises the steps of fully mixing high-purity silicon powder and high-purity carbon powder, placing the mixture in a crucible, forming a primary silicon carbide material in a high-temperature furnace at 1400-2200 ℃, then crushing the mixture, performing high-temperature oxidation at 600-1400 ℃ in an oxidation furnace to obtain a secondary silicon carbide material, and performing high-temperature oxidation in a high-vacuum furnaceVacuum degassing at 800-; and carrying out wet chemical metallurgical treatment on the obtained third-time silicon carbide material to obtain a high-purity silicon carbide raw material.
CN1163895A can directly obtain alpha-SiC micropowder, but the used composite catalyst and organic binder are easy to introduce pollution. Other methods are all that high-purity C powder is mixed with Si powder, and SiC powder is synthesized in the environment of mixed gas filled with inert gas or the mixed gas of the inert gas and reducing gas. Because the granularity of the two raw materials is small, after the two raw materials are mixed and placed in a crucible, the gas in the gap between the two raw materials is difficult to be completely pumped out under vacuum, although inert gas can be added for pumping, the impurity gas, particularly nitrogen impurities, is difficult to be removed. Patents CN101302011A and CN103508454B disclose methods for secondary synthesis and tertiary synthesis of SiC powders, which can improve the purity of the powders, but the process is complicated, and the cost of powder preparation is increased.
Disclosure of Invention
Aiming at the defects of the prior art, the rapid synthesis method of the high-purity SiC powder suitable for the growth of the semiconductor single crystal is provided.
The technical scheme of the invention is as follows:
a rapid synthesis method of high-purity SiC powder comprises the following steps:
(1) selecting high-purity C powder and Si powder according to the proportion of 1: 1.05, the purity of the C powder and the purity of the Si powder are both more than 99.998 percent;
(2) selecting high-purity Polycarbosilane (PCS) powder and the carbon-silicon powder mixed in the step (1) according to the mass ratio of 1: uniformly mixing the components in a ratio of 100; the purity of the polycarbosilane is better than 99.99 percent;
(3) putting the mixed powder in the step (2) into a high-purity graphite crucible, putting the crucible into a medium-frequency induction heating furnace, and vacuumizing;
(4) filling inert gas into the reaction chamber to 100mbar, slowly heating to 500-;
(5) introducing high-purity argon or a mixture of argon and hydrogen into the chamber, heating to 1100-1300 ℃ for synthetic reaction, wherein the reaction time is 3-5 h;
(6) filling high-purity argon and hydrogen into a cavity according to the flow ratio of 90:10, pressurizing to 600mbar, rapidly heating to 1900-;
(7) slowly cooling to room temperature under the protection of argon and hydrogen.
Preferably, in the step (3), the crucible upper cover is provided with a hole. The gas generated by decomposing the PCS can be discharged.
Preferably, in step (3), vacuum is applied to 5x10-6mbar。
Preferably, in step (4), the inert gas is H2。
The obtained powder has high purity, can meet the growth requirement of high-purity semi-insulating SiC single crystals, is simple to operate and is suitable for rapid mass production. The PCS powder was mixed with the high purity C powder and the Si powder because PCS was decomposed to generate a large amount of gas upon heating, and constituent elements contained only C, H, and no impurity contamination was introduced. The gas generated during decomposition can effectively fill gaps between the C powder and the Si powder particles to generate cavities, and is assisted with the filling and pumping of inert gas, so that impurity gas, particularly nitrogen, desorbed from the surfaces of the C powder and the Si powder during high-temperature heating is efficiently discharged by utilizing the flushing effect, and is pumped away by a mechanical pump through a small hole in the upper cover of the crucible. As the decomposition temperature of PCS is lower than the synthesis temperature of silicon carbide, the powder can be further purified before reaction, and early-stage conditions are provided for obtaining high-purity powder. After the pumping is finished, heating to 1100-1300 ℃ under the protection of high-purity inert gas, and carrying out synthetic reaction for 3-5h to obtain SiC powder. The powder particles are smaller and the impurity content is still higher. Then, according to 100: 5, introducing high-purity argon and hydrogen to 600mBar, rapidly heating to 1900-2100 ℃, and carrying out a dynamic process of decomposition and re-polymerization on the SiC powder, wherein the smaller particles gradually aggregate and change to large particles, and impurities such as impurity elements, namely nitrogen, boron, aluminum, vanadium and the like, reach an overflow temperature point and overflow from small holes of the crucible, thereby achieving the purposes of particle growth and further reduction of impurity concentration.
The invention has the beneficial effects that:
the technical scheme of the invention can meet the growth requirement of the high-purity semi-insulating SiC single crystal, is simple to operate, is suitable for rapid mass production, and further reduces the impurity concentration.
The specific implementation mode is as follows:
the present invention is further illustrated by, but is not limited to, the following examples.
Example 1:
a rapid synthesis method of high-purity SiC powder comprises the following steps:
(1) according to the molar ratio of the Si powder to the C powder of 1.05:1, the semiconductor-grade Si powder and the semiconductor-grade C powder are taken, the purity of both the Si powder and the C powder is more than 99.998%, and the particle size is less than or equal to 300 um.
(2) Selecting high-purity Polycarbosilane (PCS) powder and the carbon-silicon powder mixed in the step (1) according to the mass ratio of 1: uniformly mixing the components in a ratio of 100; the addition amount of PCS powder is 1 percent of the total mass of Si powder and C powder; the purity of the polycarbosilane is better than 99.99 percent.
(3) Uniformly mixing the powder obtained in the step (2), putting the mixture into a high-purity graphite crucible, putting the high-purity graphite crucible into a medium-frequency induction heating furnace, and vacuumizing to 5x10-6mbar。
(4) Is filled into H2The gas is pumped to 100mbar, slowly heated to 500 deg.C, pumped to 0.1mbar, re-pumped to 100mbar, and repeatedly pumped for 3 times.
(5) Introducing high-purity argon into the chamber, adjusting the pressure to 600mbar, and heating to 1100-.
(6) According to the flow ratio of 100: 5, filling high-purity argon and hydrogen into the chamber, pressurizing to 600mbar, rapidly heating to 1900-2100 ℃ for synthesis conversion reaction, and keeping the synthesis time for 15 hours to promote the particle growth and achieve the purpose of further purification.
(7) Slowly cooling to room temperature under the protection of argon and hydrogen.
Claims (4)
1. A rapid synthesis method of high-purity SiC powder is characterized by comprising the following steps:
(1) selecting high-purity C powder and Si powder according to the proportion of 1: 1.05, the purity of the C powder and the purity of the Si powder are both more than 99.998 percent;
(2) selecting high-purity Polycarbosilane (PCS) powder and the carbon-silicon powder mixed in the step (1) according to the mass ratio of 1: uniformly mixing the components in a ratio of 100; the purity of the polycarbosilane is better than 99.99 percent;
(3) putting the mixed powder in the step (2) into a high-purity graphite crucible, putting the crucible into a medium-frequency induction heating furnace, and vacuumizing;
(4) filling inert gas into the reaction chamber to 100mbar, slowly heating to 500-;
(5) introducing high-purity argon or a mixture of argon and hydrogen into the chamber, heating to 1100-1300 ℃ for synthetic reaction, wherein the reaction time is 3-5 h;
(6) filling high-purity argon and hydrogen into a cavity according to the flow ratio of 90:10, pressurizing to 600mbar, rapidly heating to 1900-;
(7) slowly cooling to room temperature under the protection of argon and hydrogen.
2. The method for rapidly synthesizing high purity SiC powder according to claim 1, wherein in the step (3), the crucible cover is provided with holes.
3. The method for rapidly synthesizing high purity SiC powder according to claim 1, wherein in the step (3), the vacuum is applied to 5x10-6mbar。
4. The method for rapidly synthesizing high purity SiC powder according to claim 1, wherein in the step (4), the inert gas is H2。
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112978732A (en) * | 2021-02-02 | 2021-06-18 | 北京绿清科技有限公司 | Production method and special production system of silicon carbide |
| CN113481603A (en) * | 2021-08-02 | 2021-10-08 | 哈尔滨科友半导体产业装备与技术研究院有限公司 | Preparation method of PVT method silicon carbide crystal growth raw material |
| CN113501525A (en) * | 2021-08-20 | 2021-10-15 | 中电化合物半导体有限公司 | Synthesis method of silicon carbide powder |
| CN113716566A (en) * | 2021-09-13 | 2021-11-30 | 浙江大学杭州国际科创中心 | Preparation method of high-purity silicon carbide source powder |
| CN114014318A (en) * | 2021-12-20 | 2022-02-08 | 中电化合物半导体有限公司 | Synthesis method of silicon carbide powder |
| CN116553555A (en) * | 2023-07-07 | 2023-08-08 | 通威微电子有限公司 | Synthesis method of large kilogram silicon carbide powder and silicon carbide powder |
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- 2019-03-19 CN CN201910207141.3A patent/CN111717918A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112978732A (en) * | 2021-02-02 | 2021-06-18 | 北京绿清科技有限公司 | Production method and special production system of silicon carbide |
| CN112978732B (en) * | 2021-02-02 | 2023-08-18 | 北京绿清科技有限公司 | Production method and special production system of silicon carbide |
| CN113481603A (en) * | 2021-08-02 | 2021-10-08 | 哈尔滨科友半导体产业装备与技术研究院有限公司 | Preparation method of PVT method silicon carbide crystal growth raw material |
| CN113501525A (en) * | 2021-08-20 | 2021-10-15 | 中电化合物半导体有限公司 | Synthesis method of silicon carbide powder |
| CN113716566A (en) * | 2021-09-13 | 2021-11-30 | 浙江大学杭州国际科创中心 | Preparation method of high-purity silicon carbide source powder |
| CN114014318A (en) * | 2021-12-20 | 2022-02-08 | 中电化合物半导体有限公司 | Synthesis method of silicon carbide powder |
| CN116553555A (en) * | 2023-07-07 | 2023-08-08 | 通威微电子有限公司 | Synthesis method of large kilogram silicon carbide powder and silicon carbide powder |
| CN116553555B (en) * | 2023-07-07 | 2023-09-26 | 通威微电子有限公司 | Synthesis method of large kilogram of silicon carbide powder |
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