Method and device for growing silicon carbide crystals
By using core-shell particles coated with a silicon carbide shell around a germanium core, combined with fluidized bed chemical vapor deposition and physical vapor transport, the problem of uneven doping during the growth of germanium-doped silicon carbide crystals was solved, and high-quality growth of germanium-doped silicon carbide crystals was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG SCI-TECH UNIV
- Filing Date
- 2026-01-19
- Publication Date
- 2026-05-12
AI Technical Summary
In existing technologies, uneven doping during the growth of germanium-doped silicon carbide crystals leads to a decrease in crystal quality.
Fluidized bed chemical vapor deposition (FB-CVD) is used to coat a germanium core with a silicon carbide shell to form core-shell particles. These particles are then used as raw materials to grow silicon carbide crystals via physical vapor transport (PVT) method. By controlling the growth temperature and pressure, uniform germanium doping is achieved.
Precise control of germanium doping concentration within the range of 5×10¹⁶ atoms/cm³ to 5×10¹⁹ atoms/cm³ was achieved, improving the uniformity of germanium doping and the quality of silicon carbide crystals.
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Figure CN122013306A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of silicon carbide crystal preparation technology, and particularly relates to a method and apparatus for growing silicon carbide crystals. Background Technology
[0002] Silicon carbide (SiC) crystal is the core material of third-generation wide bandgap semiconductors. It has advantages such as large bandgap, high thermal conductivity, high breakdown electric field strength, and fast electron saturation drift speed. It is widely used in power devices, radio frequency devices, optoelectronic devices and other fields.
[0003] Germanium (Ge) doping can optimize the lattice matching, band structure, and electrical properties of silicon carbide (SiC) crystals, thereby improving device yield. Currently, Ge doping mainly involves directly mixing Ge and SiC raw materials or pressing them into bulk form for crystal growth.
[0004] For example, patent CN115161762B discloses a method for growing silicon carbide ingots using a germanium-silicon-carbon ternary alloy solid, comprising the following steps: mixing carbon powder, silicon powder, and germanium powder uniformly to form a mixed powder, pressing the mixed powder into a cake; placing the mixed powder cake into a reactor and firing it to form a germanium-silicon-carbon ternary alloy solid; using the germanium-silicon-carbon ternary alloy solid as a raw material to grow silicon carbide crystals based on the PVT method, thereby obtaining germanium-doped silicon carbide ingots; wherein, the mass fraction ratio of Ge and C in the germanium-silicon-carbon ternary alloy solid is determined according to the lattice constant of the silicon carbide seed crystal used in the PVT method, so that the lattice constant of the germanium-silicon-carbon ternary alloy is consistent with that of the silicon carbide seed crystal. By using the germanium-silicon-carbon ternary alloy solid as a raw material to grow silicon carbide crystals, it is possible to obtain silicon carbide ingots with uniform germanium doping, which is beneficial to improving the yield of germanium-doped silicon carbide products.
[0005] However, the sublimation point of germanium (Ge) powder is about 1200℃, while the growth temperature of SiC exceeds 2000℃. Germanium is already depleted through volatilization in the early stages of growth, resulting in a sharp drop in vertical doping concentration and uneven doping.
[0006] Therefore, there is an urgent need to develop a method and apparatus for growing silicon carbide crystals to solve the problems in the existing technology. Summary of the Invention
[0007] The purpose of this invention is to provide a method and apparatus for growing silicon carbide crystals. By coating a germanium core with a silicon carbide shell, the low-melting-point material germanium is completely coated with the high-melting-point material silicon carbide, thus avoiding the uneven release of germanium during the growth process and solving the problem of uneven doping of germanium-doped silicon carbide crystals mentioned in the background art.
[0008] To solve the above-mentioned technical problems, the specific technical solution of the present invention is as follows:
[0009] A method and apparatus for growing silicon carbide crystals, comprising the following steps:
[0010] Obtaining core-shell particles and silicon carbide powder; wherein, the core-shell particles include a core and a shell, the shell covering the core, the core being germanium, and the shell being silicon carbide;
[0011] Silicon carbide crystals were grown using core-shell particles and silicon carbide powder as growth materials via the PVT method. The growth temperature for silicon carbide crystal growth was 2100℃~2300℃, the growth pressure was 5mbar-30mbar, and the growth time was 50 hours-200 hours.
[0012] Furthermore, the core has a particle size of 5um-30um, and the shell has a thickness of 5um-40um.
[0013] Furthermore, the particle size of the core-shell particles is 10um-50um.
[0014] Furthermore, the mass ratio of the core-shell particles to the silicon carbide powder is determined based on the germanium concentration required to be doped into the silicon carbide crystal.
[0015] Furthermore, the core-shell particles are mixed with silicon carbide powder at a mass ratio of 1:99 - 30:70.
[0016] Furthermore, the core-shell particles are obtained by coating a silicon carbide layer onto the surface of germanium seed crystals through fluidized bed chemical vapor deposition.
[0017] Furthermore, the preparation of the core-shell particles includes the following steps:
[0018] Germanium seed crystals are placed into a fluidized bed reactor;
[0019] The silicon source and the carbon source are introduced into the fluidized bed reactor;
[0020] A vapor-phase deposition reaction is carried out in a fluidized bed reactor to obtain the reaction products;
[0021] Core-shell particles of suitable size were separated from the reaction products;
[0022] The temperature of the vapor deposition reaction is controlled within the range of 600℃-900℃, the pressure is controlled within the range of 0.5 MPa to 1 MPa, and the carrier gas flow rate is controlled within the range of 150 L / min-250 L / min.
[0023] Furthermore, the separation of core-shell particles of suitable size from the reaction products includes the following steps:
[0024] The reaction products inside the fluidized bed reactor are discharged from the fluidized bed reactor;
[0025] Core-shell particles of suitable size are separated from the reaction products using sieves of different sizes.
[0026] Furthermore, the silicon source includes methyltrichlorosilane, trichlorosilane, or dichlorosilane, and the carbon source includes ethylene or acetylene; the germanium seed crystals have a particle size of 5µm-30µm and a purity greater than 6n.
[0027] A computer device includes a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method.
[0028] The present invention has the following advantages:
[0029] This application utilizes fluidized bed chemical vapor deposition (FB-CVD) to coat germanium with a silicon carbide layer, forming "Ge@SiC" core-shell particles of suitable size. These core-shell particles are then mixed with conventional silicon carbide powder at an appropriate mass ratio as a PVT growth feedstock. Crystal growth is achieved using a growth pressure of 5 mbar-30 mbar and a growth temperature of 2100℃-2300℃, resulting in a germanium doping concentration of 5 × 10⁻⁶ for the silicon carbide crystal. 16 atoms / cm 3 ~ 5×10 19 atoms / cm 3 With precise control within the specified range, this application also improves the uniformity of germanium doping and the quality of silicon carbide crystals compared to conventional methods for preparing germanium-doped silicon carbide crystals.
[0030] Other features and advantages of the present invention will be disclosed in detail in the following detailed description and accompanying drawings. Attached Figure Description
[0031] Figure 1 This is a schematic diagram of the growth process of this application;
[0032] Figure 2 This is a schematic diagram of the structure of the core-shell particles in this application;
[0033] Figure 3 A schematic diagram showing the quality of the germanium-doped silicon carbide crystal prepared in this application;
[0034] Figure 4 This is a schematic diagram of the quality of a typical germanium-doped silicon carbide crystal. Detailed Implementation
[0035] To better understand the purpose, structure, and function of this invention, the invention will be described in further detail below with reference to the accompanying drawings.
[0036] A method for growing silicon carbide crystals, such as Figure 1As shown, it includes the following steps:
[0037] Obtain core-shell particles and silicon carbide powder; wherein, such as Figure 2 As shown, the core-shell particle includes a core and a shell, the shell covering the surface of the core, the core being germanium, and the shell being silicon carbide;
[0038] Silicon carbide crystals were grown using core-shell particles and silicon carbide powder as growth materials via the PVT method. The growth temperature was 2100℃~2300℃, the growth pressure was 5mbar-30mbar, and the growth time was 50 hours-200 hours.
[0039] Specifically, silicon carbide crystal growth via the PVT method is an existing technology, and will not be described further in this application.
[0040] In this embodiment, preferably, the core particle size is 5um-30um, and the shell thickness is 5um-40um. The core-shell particles have a particle size of 10um-50um.
[0041] The combination of the core of this particle size and the shell of this thickness in the silicon carbide crystal growth environment of this application helps to improve the uniformity of germanium doping and effectively improve the quality of silicon carbide crystals.
[0042] The mass ratio of the core-shell particles to the silicon carbide powder is determined based on the required germanium doping concentration in the silicon carbide crystal. Preferably, the core-shell particles and silicon carbide powder are mixed at a mass ratio of 1:99 to 30:70.
[0043] In this embodiment, the core-shell particles are obtained by chemical vapor deposition of a silicon carbide layer onto the surface of a germanium seed crystal.
[0044] Specifically, the preparation of the core-shell particles includes the following steps:
[0045] Germanium seed crystals are placed in a fluidized bed reactor; wherein the germanium seed crystals have a particle size of 5um-30um and a purity greater than 6n;
[0046] A silicon source and a carbon source are introduced into a fluidized bed reactor; wherein, methyltrichlorosilane (CH3SiCl3), trichlorosilane (SiHCl3) or dichlorosilane (SiH2Cl2) are used as silicon sources, and ethylene (C2H4) or acetylene (C2H2) are used as carbon sources.
[0047] A vapor-phase deposition reaction is carried out in a fluidized bed reactor to obtain the reaction products; wherein the temperature of the vapor-phase deposition reaction is controlled within the range of 600℃-900℃, the pressure is controlled within the range of 0.5 MPa to 1 MPa, and the carrier gas flow rate is controlled within the range of 150 L / min-250 L / min. In this embodiment, the carrier gas is Ar.
[0048] Core-shell particles of suitable size were separated from the reaction products.
[0049] In this embodiment, separating core-shell particles of suitable size from the reaction product includes the following steps:
[0050] The reaction products in the fluidized bed reactor are discharged from the fluidized bed reactor through a particulate discharge device;
[0051] Core-shell particles of suitable size are separated from the reaction products by using sieves of different coarseness, wherein the suitable particle size is in the range of 10um-50um.
[0052] The exhaust gas is discharged from the fluidized bed reactor through a gas emission device.
[0053] In this embodiment, the subsequent silicon carbide crystal growth method specifically includes the following:
[0054] Core-shell particles with a core diameter of approximately 10 μm and a shell thickness of approximately 15 μm prepared by fluidized bed were mixed with silicon carbide powder at a mass ratio of 1:10 to obtain the growth raw material.
[0055] Place the prepared growth raw materials and seed crystals and other materials required for growth into a crucible and load it into the growth furnace;
[0056] Crystals were grown in a growth furnace using the PVT method; the upper growth temperature was 2100℃, the lower growth temperature was 2300℃, the growth pressure was 7 mbar, and the growth time was 150 h.
[0057] like Figure 3 The diagram shown is a dislocation density map of the late stage of wafer growth in the crystal prepared in this embodiment, which shows that there are relatively few dislocations.
[0058] like Figure 4 The figure shows the dislocation density diagram in the later stage of crystal growth of a crystal prepared by existing technology. It can be seen that Ge volatilizes excessively in the early stage and is insufficient in the later stage of growth, resulting in more dislocations.
[0059] contrast Figure 3 and Figure 4 It can be seen that the method of this application significantly improves the uniformity of Ge volatilization over time and significantly reduces crystal dislocations.
[0060] The present invention discloses a method for preparing germanium-containing silicon carbide particles. Using germanium as a seed crystal, silicon and carbon source gases are introduced into a fluidized bed reactor for vapor deposition. By controlling the temperature and pressure of the vapor deposition reaction within the fluidized bed reactor, the reaction products are discharged from the reactor via a particle discharge device. Germanium-containing silicon carbide particles are then separated from the reaction products. The low-melting-point germanium is completely coated with high-melting-point silicon carbide, avoiding uneven release of germanium during growth. This simple production process effectively improves the quality of silicon carbide crystals.
[0061] In summary, this application first employs fluidized bed chemical vapor deposition (FB-CVD) with 5µm-30µm Ge as the core, controlling the temperature at 600℃-900℃, and selecting precursors with sufficient reactivity at lower temperatures. The silicon source is selected from methyltrichlorosilane (CH3SiCl3), trichlorosilane (SiHCl3), or dichlorosilane (SiH2Cl2); the carbon source is selected from ethylene (C2H4) or acetylene (C2H2), etc. By controlling appropriate precursor concentrations and flow rates, core-shell structures of different particle sizes are formed, creating "Ge@SiC" core-shell particles, thus achieving the coating of silicon carbide onto the surface of germanium particles. The precursor is a silicon source with a flow rate of 1L / min-10L / min. Secondly, this application uses a mixture of Ge@SiC core-shell particles and conventional SiC powder at a mass ratio of 1:99 to 30:70 as a PVT growth material for crystal growth. Finally, under an environment with a growth pressure of 5 mbar-30 mbar and a growth temperature of 2100℃-2300℃, the germanium doping concentration of 5 × 10⁻⁶ is achieved by adjusting the mixing ratio of the core-shell particles and silicon carbide powder. 16 atoms / cm 3 ~5×10 19 atoms / cm 3 Precise control within the specified range.
[0062] A computer device includes a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method.
[0063] A computer program product includes a computer program that, when executed by a processor, implements the steps of the method.
[0064] A computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements the steps of the method.
[0065] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.
[0066] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A method and apparatus for growing silicon carbide crystals, characterized in that, Includes the following steps: Obtaining core-shell particles and silicon carbide powder; wherein, the core-shell particles include a core and a shell, the shell covering the core, the core being germanium, and the shell being silicon carbide; Silicon carbide crystals were grown using core-shell particles and silicon carbide powder as growth materials via the PVT method. The growth temperature for silicon carbide crystal growth was 2100℃~2300℃, the growth pressure was 5mbar-30mbar, and the growth time was 50 hours-200 hours.
2. The method for growing silicon carbide crystals according to claim 1, characterized in that, The core has a particle size of 5um-30um, and the shell has a thickness of 5um-40um.
3. The method for growing silicon carbide crystals according to claim 2, characterized in that, The core-shell particles have a particle size of 10µm-50µm.
4. The method for growing silicon carbide crystals according to any one of claims 1-3, characterized in that, The mass ratio of the core-shell particles to the silicon carbide powder is determined based on the germanium concentration required to be doped into the silicon carbide crystal.
5. The method for growing silicon carbide crystals according to claim 4, characterized in that, The core-shell particles and silicon carbide powder are mixed at a mass ratio of 1:99 - 30:
70.
6. The method for growing silicon carbide crystals according to any one of claims 1-3 or 5, characterized in that, The core-shell particles are obtained by coating a silicon carbide layer onto the surface of germanium seed crystals through fluidized bed chemical vapor deposition.
7. The method for growing silicon carbide crystals according to claim 6, characterized in that, The preparation of the core-shell particles includes the following steps: Germanium seed crystals are placed into a fluidized bed reactor; Silicon and carbon sources are introduced into the fluidized bed reactor; A vapor-phase deposition reaction is carried out in a fluidized bed reactor to obtain the reaction products; Core-shell particles of suitable size were separated from the reaction products; The temperature of the vapor deposition reaction is controlled within the range of 600℃-900℃, the pressure is controlled within the range of 0.5 MPa to 1 MPa, and the carrier gas flow rate is controlled within the range of 150 L / min-250 L / min.
8. The method for growing silicon carbide crystals according to claim 7, characterized in that, The separation of core-shell particles of suitable size from the reaction products includes the following steps: The reaction products inside the fluidized bed reactor are discharged from the fluidized bed reactor; Core-shell particles of suitable size are separated from the reaction products using sieves of different sizes.
9. The method for growing silicon carbide crystals according to claim 7 or 8, characterized in that, The silicon source includes methyltrichlorosilane, trichlorosilane, or dichlorosilane; the carbon source includes ethylene or acetylene; the germanium seed crystals have a particle size of 5µm-30µm and a purity greater than 6n.
10. A computer device comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the steps of the method according to any one of claims 1-9.