A device for preparing silicon carbide single crystal by chemical vapor deposition method
Silicon carbide single crystals are prepared in a glass cylinder by chemical vapor deposition method, and low-concentration methylsilane gas and cold hydrogen are used to control current and rotate seed crystals, which solves the problems of large gas phase decomposition amount and powdered amorphous silicon generation in the prior art, and achieves efficient and low-defect silicon single crystal growth.
Patent Information
- Application Number
- CN202421499891.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-28
- Publication Date
- 2025-04-11
- Estimated Expiration
- 2034-06-28
AI Technical Summary
In the prior art, when preparing silicon single crystals, the gas phase decomposition amount is large and a large amount of powdered amorphous silicon is generated. The preparation steps are complicated, and the growth of silicon carbide single crystals is limited, making it difficult to achieve efficient and low-defect crystal growth.
Using chemical vapor deposition method, by setting up a chemical vapor deposition chamber in a glass cylinder, low-concentration methylsilane gas and cold hydrogen, controlling current and rotating seed crystals, the surface reaction generation and deposition of silicon carbide is achieved, reducing the amount of gas phase decomposition and the generation of powdered amorphous substances.
The production of low gas phase decomposition amount and small amount of powdered amorphous substances is achieved, and the prepared silicon carbide single crystal has few defects, the growth rate is increased by 2-3 orders of magnitude, shortening the production cycle, reducing time costs and fixed asset investment.
Smart Images
Figure CN222744443U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of electronic special material manufacturing, in particular to a device for preparing silicon carbide single crystal by chemical vapor deposition method. Background Art
[0002] As an excellent semiconductor material, single crystal silicon has many advantages such as good conductivity, stable chemical properties, high thermal stability, strong mechanical plasticity, etc., and has excellent applications in the fields of electronics and optoelectronics. However, the current method of preparing silicon single crystals using silane produces a large amount of gas phase decomposition during the preparation of silicon single crystals, and a large amount of powdered amorphous silicon is generated, and the preparation steps are complicated.
[0003] At the same time, silicon carbide is the most widely used basic material for making semiconductor chips in the future due to its superior physical properties: high bandgap width (corresponding to high breakdown electric field and high power density), high electrical conductivity, and high thermal conductivity. It is used to make power devices, which can significantly improve the utilization rate of electric energy. In the foreseeable future, new energy vehicles are the main application scenarios of silicon carbide power devices. As a technological pioneer, Tesla has taken the lead in integrating full silicon carbide modules in Model 3, and other first-tier car companies are also planning to expand the application of silicon carbide. With the gradual reduction of the manufacturing cost of silicon carbide devices and the gradual maturity of process technology, the silicon carbide power device industry is promising in the future. Silicon carbide (SiC), as a third-generation compound semiconductor material, is the main direction of progress and development in the power semiconductor industry. At present, silicon carbide single crystals are prepared by heating and sublimating silicon carbide powder loaded in a graphite crucible, which is the so-called PVT (physical method). The PVT method uses silicon carbide solid raw materials, which have a limited filling amount and a limited length of the grown crystal. The chemical vapor deposition process of the present invention can continuously supply gas source materials to the furnace chamber, thereby achieving continuous growth of crystals. Furthermore, the present invention adopts gas-phase raw materials with high purity and extremely low crystal impurities; further, the gas raw materials of the present invention directly undergo chemical reactions on the surface of the seed crystal to generate crystals, and the silicon / carbon ratio of the growth process can be effectively controlled by the gas flow rate, thereby reducing crystal defects caused by deviations from the dose ratio, and at the same time, the doping amount, crystal type, etc. can also be effectively controlled, and the prepared n-type or p-type silicon carbide crystals have fewer defects; further, the crystal growth rate of the present invention is 2 to 3 orders of magnitude of the growth rate of the PVT method, which can not only greatly shorten the production cycle and reduce time costs, but also reduce the fixed asset investment in the single crystal furnace.
[0004] Therefore, a device for preparing silicon carbide single crystal by chemical vapor deposition is proposed to solve the above-mentioned problems. Utility Model Content
[0005] The purpose of the utility model is to provide a device for preparing silicon carbide single crystal by chemical vapor deposition method, so as to solve the problems raised in the above background technology.
[0006] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: a device for preparing silicon carbide single crystal by chemical vapor deposition method, comprising a first glass cylinder and a second glass cylinder, the second glass cylinder is arranged at the lower end of the first glass cylinder, the upper end of the first glass cylinder is fixedly provided with a first metal end cap, the lower side wall of the second glass cylinder is fixedly provided with a second metal end cap, a sealing ring is fixedly provided in the middle of the first glass cylinder and the second glass cylinder on the side close to each other, the upper side wall and the lower side wall of the sealing ring are both provided with polychloroprene rubber gaskets, and the two polychloroprene rubber gaskets are respectively connected to the first glass cylinder on the opposite sides. The first glass cylinder and the second glass cylinder are in contact with each other, a primary coil is arranged outside the connection between the first glass cylinder and the second glass cylinder, a secondary coil is arranged inside the primary coil, an insulating pad is arranged between the primary coil and the secondary coil, a working coil is arranged inside the first glass cylinder and the second glass cylinder, a shaft is rotatably arranged on the side wall of the second metal end cap, a silicon single crystal seed crystal is arranged on the upper end of the shaft, a gas inlet pipe is fixedly arranged on the side wall of the first metal end cap, an outlet pipe is fixedly arranged on the side wall of the second metal end cap, a slit is opened on the upper end of the outlet pipe, and a symmetrical brush is fixedly arranged on the side wall of the shaft;
[0007] A thick tube and a thin tube are arranged inside the gas inlet tube.
[0008] Preferably, the interiors of the first glass cylinder and the second glass cylinder constitute a chemical vapor deposition chamber.
[0009] Preferably, the upper end of the outlet pipe is annular.
[0010] Preferably, the number of the thick tubes is 3-20, and the number of the thin tubes is 6-60.
[0011] Compared with the prior art, the beneficial effects of the utility model are:
[0012] By introducing low-concentration methylsilane gas and inert gas around, and adjusting specific parameters, the minimum gas phase decomposition amount can be obtained and the generated powdery amorphous material can be reduced. The operation process of this method involves rotating seed crystals, introducing methylsilane gas and cold hydrogen, controlling current and other steps to achieve surface reaction generation and deposition of silicon carbide. In addition to hydrogen, other gases that are inert to methylsilane and thermal decomposition products can also be used as protective gases. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 It is a schematic diagram of the structure of the present invention;
[0014] Figure 2 Schematic diagram of the cross section of the gas inlet pipe.
[0015] In the figure: 1 first glass cylinder, 2 second glass cylinder, 3 first metal end cap, 4 second metal end cap, 5 polychloroprene rubber gasket, 6 sealing ring, 7 primary coil, 8 secondary coil, 9 insulating pad, 10 working coil, 11 shaft, 12 silicon single crystal seed crystal, 13 gas inlet pipe, 14 outlet pipe, 15 slit, 16 brush, 17 thick pipe, 18 thin pipe. DETAILED DESCRIPTION
[0016] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0017] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.
[0018] Example:
[0019] See also Figure 1-2 , the utility model provides a technical solution:
[0020] A device for preparing silicon carbide single crystal by chemical vapor deposition method comprises a first glass cylinder 1 and a second glass cylinder 2, wherein the second glass cylinder 2 is arranged at the lower end of the first glass cylinder 1, a first metal end cap 3 is fixedly arranged at the upper end of the first glass cylinder 1, a second metal end cap 4 is fixedly arranged at the lower side wall of the second glass cylinder 2, a sealing ring 6 is fixedly arranged in the middle of the side where the first glass cylinder 1 and the second glass cylinder 2 are close to each other, a polychloroprene rubber gasket 5 is arranged on the upper side wall and the lower side wall of the sealing ring 6 (silicon rubber or fluororubber gaskets can also be arranged on the upper side wall and the lower side wall of the sealing ring 6), and the two polychloroprene rubber gaskets 5 are respectively in contact with the side walls of the first glass cylinder 1 and the second glass cylinder 2 on the opposite sides. A primary coil 7 is arranged outside the connection of the first glass cylinder 1 and the second glass cylinder 2, a secondary coil 8 is arranged inside the primary coil 7, an insulating pad 9 is arranged between the primary coil 7 and the secondary coil 8, a working coil 10 is arranged inside the first glass cylinder 1 and the second glass cylinder 2, a shaft 11 is rotatably arranged on the side wall of the second metal end cover 4, a silicon single crystal seed crystal 12 is arranged on the upper end of the shaft 11 (a silicon carbide single crystal seed crystal can also be arranged on the upper end of the shaft 11), a gas inlet pipe 13 is fixedly arranged on the side wall of the first metal end cover 3, an outlet pipe 14 is fixedly arranged on the side wall of the second metal end cover 4, a slit 15 is opened on the upper end of the outlet pipe 14, and a symmetrical brush 16 is fixedly arranged on the side wall of the shaft 11;
[0021] A thick tube 17 and a thin tube 18 are arranged inside the gas inlet tube 13 .
[0022] The interior of the first glass cylinder 1 and the second glass cylinder 2 constitutes a chemical vapor deposition chamber, which is made of high-purity quartz glass.
[0023] The upper end of the outlet pipe 14 is in a circular ring shape.
[0024] The number of thick tubes 17 is 3 to 20, and the number of thin tubes 18 is 6 to 60.
[0025] The shaft 11 is used to place a silicon single crystal seed crystal 12. It must be able to rotate and move axially relative to the decomposition chamber. Gas can be introduced into the decomposition chamber through the gas inlet pipe 13 and can be led out through the outlet pipe 14. One end of the outlet pipe 14 is annular, and a slit 15 is cut on the inner side. The other end of the outlet pipe is connected to a vacuum pump (not shown). Two brushes 16 are installed on the shaft 11 to prevent the slit 15 from being blocked by silicon carbide powder.
[0026] (The same apparatus described above is also applicable to the preparation of silicon crystals).
[0027] Working principle:
[0028] The radio frequency current in the primary coil 7 causes the secondary coil 8 and the working coil 10 to excite current in the silicon carbide single crystal seed crystal 12. These currents must be large enough to make the top of the seed crystal reach or exceed the decomposition temperature of the methylsilane gas;
[0029] The silicon carbide single crystal seed crystal 12 and the brush 16 rotate with the shaft 11. Very pure methylsilane gas is introduced from n thick tubes 17 in the gas inlet pipe 13, and its molecular concentration is less than the concentration at normal pressure. Cold hydrogen enters from n smaller thin tubes 18. Methylsilane hits the top of the hot silicon carbide single crystal seed crystal 12 and immediately decomposes into silicon carbide and hydrogen on its surface and near the hot zone. The undecomposed methylsilane is discharged through the outlet pipe 14 together with the hydrogen from the gas inlet pipe 13 and the hydrogen produced by decomposition;
[0030] During the entire growth process of the silicon carbide single crystal seed crystal 12, the shaft 11 slowly descends, and the descending speed makes the relative position of the seed crystal top and the working coil 10 consistent;
[0031] Step 4: Even if there is a suitable space between the working coil 10 and the seed crystal 12, a certain amount of methylsilane will still decompose in the space of hot hydrogen produced during the decomposition process and around the silicon carbide single crystal seed crystal 12. Such a gas phase decomposition increases the powdered amorphous silicon carbide. In order to prevent the hot gas from entering the area near the top of the seed crystal, cold hydrogen is introduced through the capillary 18. The hydrogen forms a cold zone around the methylsilane gas, so that the decomposed hot hydrogen is limited to the smallest possible range and promotes the contact between the silicon single crystal seed crystal, methylsilane and the top of the silicon carbide seed crystal 12. Therefore, silicon carbide is produced by surface reaction rather than gas phase reaction, and most of the silicon carbide is deposited on the silicon carbide seed crystal 12 to form dense silicon carbide crystals rather than powdered amorphous silicon carbide.
[0032] The above shows and describes the basic principle and main features of the utility model and the advantages of the utility model. For those skilled in the art, it is obvious that the utility model is not limited to the details of the above exemplary embodiments, and the utility model can be implemented in other specific forms without departing from the spirit or basic features of the utility model; therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the utility model is limited by the attached claims rather than the above description. Therefore, it is intended to include all changes within the meaning and scope of the equivalent elements of the claims in the utility model, and any figure marks in the claims should not be regarded as limiting the claims involved.
[0033] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A device for preparing silicon carbide single crystal by chemical vapor deposition, comprising a first glass cylinder (1) and a second glass cylinder (2), characterized in that: The second glass cylinder (2) is arranged at the lower end of the first glass cylinder (1); a first metal end cap (3) is fixedly arranged at the upper end of the first glass cylinder (1); a second metal end cap (4) is fixedly arranged at the lower side wall of the second glass cylinder (2); a sealing ring (6) is fixedly arranged in the middle of the side where the first glass cylinder (1) and the second glass cylinder (2) are close to each other; polychloroprene rubber gaskets (5) are arranged on the upper side wall and the lower side wall of the sealing ring; the two polychloroprene rubber gaskets (5) are in contact with the side walls of the first glass cylinder (1) and the second glass cylinder (2) respectively on the opposite sides; a primary coil (6) is arranged outside the connection between the first glass cylinder (1) and the second glass cylinder (2) 7), a secondary coil (8) is arranged inside the primary coil (7), an insulating pad (9) is arranged between the primary coil (7) and the secondary coil (8), a working coil (10) is arranged inside the first glass cylinder (1) and the second glass cylinder (2), a shaft (11) is rotatably arranged on the side wall of the second metal end cover (4), a silicon single crystal seed crystal (12) is arranged on the upper end of the shaft (11), a gas inlet pipe (13) is fixedly arranged on the side wall of the first metal end cover (3), an outlet pipe (14) is fixedly arranged on the side wall of the second metal end cover (4), a slit (15) is opened at the upper end of the outlet pipe (14), and a symmetrical brush (16) is fixedly arranged on the side wall of the shaft (11); A thick tube (17) and a thin tube (18) are arranged inside the gas inlet tube (13).
2. The device for preparing silicon carbide single crystal by chemical vapor deposition method according to claim 1, characterized in that: The interiors of the first glass cylinder (1) and the second glass cylinder (2) constitute a chemical vapor deposition chamber.
3. The device for preparing silicon carbide single crystal by chemical vapor deposition method according to claim 1, characterized in that: The upper end of the outlet pipe (14) is in a circular ring shape.
4. The device for preparing silicon carbide single crystal by chemical vapor deposition method according to claim 1, characterized in that: The number of the thick tubes (17) is 3 to 20, and the number of the thin tubes (18) is 6 to 60.