Silicon carbide single crystal growth device

Abstract

The utility model relates to the field of silicon carbide single crystal growth, and discloses a silicon carbide single crystal growth device which comprises a lower frame, an upper frame is fixedly connected to the top end of the lower frame, a servo lifting mechanism is arranged in the lower frame, and the servo lifting mechanism comprises a gear motor fixedly connected to the top end in the lower frame. An output shaft of the gear motor is fixedly connected with a screw rod which is movably assembled in the lower frame. The silicon carbide single crystal growth device is provided with the servo lifting mechanism and the servo rotating mechanism to cooperatively control the crucible to rotate and lift and the coil to move relatively, so that the position of a heating area and a crystal growth interface are always kept in thermal field consistency, and the silicon carbide single crystal growth device adapts to the change of heat conduction conditions in the growth process; a heating temperature field can be accurately reconstructed in different crystal growth stages, the crystal quality stability is improved, the growth rate is greatly improved compared with a traditional process, and the problem that a fixed crucible and a static heating coil cannot adapt to the dynamically changing temperature field requirement in the growth process is solved.

Description

Technical Field

[0001] This utility model relates to the field of silicon carbide single crystal growth technology, specifically to a silicon carbide single crystal growth device. Background Technology

[0002] Silicon carbide (SiC) is a wide-bandgap semiconductor material with excellent properties such as high breakdown electric field, high thermal conductivity, and high saturated electron drift velocity. It is widely used in high-temperature, high-voltage, high-frequency, and high-power electronic devices. Currently, the mainstream method for preparing SiC single crystals is the physical vapor transport (PVT) method. This process involves sublimating SiC raw materials at high temperatures and then depositing the sublimated gas onto a seed crystal under temperature difference to form a single crystal. However, existing processes have some drawbacks, such as:

[0003] Non-uniform temperature field: The traditional PVT method uses a fixed crucible and static heating coil, which makes it difficult to accurately control the axial / radial temperature gradient, and defects such as polymorphism and dislocations are prone to appear at the crystal growth interface.

[0004] Low raw material utilization: Due to the limited sublimation gas transport rate, a recrystallization zone is easily formed in the middle of the crucible, reducing the raw material conversion efficiency.

[0005] Insufficient dynamic control: Existing improvement schemes (such as zoned heating and graphite rod-assisted heating) only optimize the static temperature field and cannot adapt to the dynamically changing temperature field requirements during growth.

[0006] Therefore, a silicon carbide single crystal growth device is needed to solve the above-mentioned technical defects. Utility Model Content

[0007] The purpose of this invention is to provide a silicon carbide single crystal growth apparatus to solve the problem mentioned in the background art that the fixed crucible and static heating coil cannot adapt to the dynamically changing temperature field requirements during the growth process.

[0008] To achieve the above objectives, this utility model provides the following technical solution: a silicon carbide single crystal growth apparatus, comprising a lower frame, an upper frame fixedly connected to the top of the lower frame, a servo lifting mechanism disposed inside the lower frame, the servo lifting mechanism comprising a geared motor fixedly connected to the top of the lower frame, a screw fixedly connected to the output shaft of the geared motor, the screw being movably assembled inside the lower frame, a threaded lifting seat and a lifting platform movably connected to the outside of the screw, a water-cooling cavity fixedly connected to the left side of the threaded lifting seat, a growth cavity communicating with the top of the water-cooling cavity, a heat-conducting sleeve covering the outer wall of the growth cavity, an induction coil wound around the outer wall of the heat-conducting sleeve; a servo rotation mechanism mounted on the top of the lifting platform; the servo rotation mechanism comprising a set of servo rotation motors fixedly connected to the top of the lifting platform, a water-cooling rod fixedly connected to the output shaft of the servo rotation motor, a connector fixedly connected to the top of the water-cooling rod, and a crucible fixedly connected to the water-cooling rod through the connector.

[0009] As a further technical solution of this utility model, the water-cooling rod passes through the water-cooling cavity and extends into the growth cavity, and the crucible is located at the center of the growth cavity.

[0010] As a further technical solution of this utility model, the output shaft speed range of the servo rotary motor is 0-20 RPM.

[0011] As a further technical solution of this utility model, the crucible descends at a speed of 1.5 mm / h, and the threaded lifting seat rises at a speed of 1 mm / h.

[0012] As a further technical solution of this utility model, a top cover is sealed at the top of the growth chamber, and an air hole is opened on the top of the top cover.

[0013] As a further technical solution of this utility model, the upper frame and the lower frame are bolted together, and the induction coil is welded to the outer wall of the heat-conducting sleeve.

[0014] Compared with the prior art, the beneficial effects of this utility model are: the silicon carbide single crystal growth device not only realizes dynamic temperature field optimization by coordinating the rotation and lifting of the crucible and the relative movement of the coil, thereby improving the crystal growth rate and quality, and realizes real-time adjustment of the crucible position and the temperature zone position, but also improves gas transmission efficiency and reduces the recrystallization area.

[0015] (1) By setting up a servo lifting mechanism and a servo rotating mechanism, the crucible rotation and lifting are controlled in coordination with the relative movement of the coil, so that the position of the heating zone and the crystal growth interface always maintain the consistency of the thermal field, adapt to the changes in heat conduction conditions during the growth process, and break through the problem of fixed and unadjustable temperature field of traditional PVT device. This allows the heating temperature field to be accurately reconstructed at different stages of crystal growth, improves the stability of crystal quality, and greatly improves the growth rate compared with traditional processes.

[0016] (2) By setting a servo rotary motor, the raw materials in the crucible are heated more evenly, suppressing non-uniform sublimation caused by local high temperature, preventing the raw materials from concentrated sublimation to form polycrystalline nuclei, thereby improving the overall lattice quality and structural integrity of silicon carbide single crystals, especially suitable for high-quality preparation of large-size crystals of 6 inches and above.

[0017] (3) By setting up a servo lifting mechanism, since the crucible and the induction coil move in opposite directions and are synchronously controlled, the growth area is continuously in the optimal temperature gradient zone, and the sublimation gas smoothly migrates from the raw material area to the seed crystal area, effectively reducing the formation of recrystallization zone and improving the raw material utilization rate. Attached Figure Description

[0018] Figure 1 This is a frontal cross-sectional view of the present invention.

[0019] Figure 2 This is a front view schematic diagram of the crucible structure of this utility model;

[0020] Figure 3 This is a front view schematic diagram of the growth chamber structure of this utility model;

[0021] Figure 4 This is a front view schematic diagram of the induction coil structure of this utility model.

[0022] In the diagram: 1. Lower frame; 2. Screw; 3. Gear motor; 4. Water-cooled rod; 5. Connector; 6. Crucible; 7. Heat-conducting sleeve; 8. Top cover; 9. Vent; 10. Induction coil; 11. Upper frame; 12. Growth chamber; 13. Water-cooled chamber; 14. Threaded lifting seat; 15. Servo rotary motor; 16. Lifting platform. Detailed Implementation

[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0024] Please see Figure 1-4 This utility model provides an embodiment of a silicon carbide single crystal growth apparatus, comprising a lower frame 1, an upper frame 11 fixedly connected to the top of the lower frame 1, a servo lifting mechanism inside the lower frame 1, a reduction motor 3 fixedly connected to the top of the lower frame 1, a screw 2 fixedly connected to the output shaft of the reduction motor 3, the screw 2 being movably mounted inside the lower frame 1, a threaded lifting seat 14 and a lifting platform 16 movably connected to the outside of the screw 2, a water-cooling cavity 13 fixedly connected to the left side of the threaded lifting seat 14, and a growth chamber 16 communicating with the top of the water-cooling cavity 13. The growth chamber 12 is covered with a heat-conducting sleeve 7 on its outer wall, and an induction coil 10 is wound around the outer wall of the heat-conducting sleeve 7. A servo rotation mechanism is installed at the top of the lifting platform 16. The servo rotation mechanism includes a set of servo rotation motors 15 fixed to the top of the lifting platform 16. The output shaft of the servo rotation motors 15 is fixedly connected to a water-cooling rod 4. A connector 5 is fixedly connected to the top of the water-cooling rod 4. A crucible 6 is fixedly connected to the water-cooling rod 4 through the connector 5. The water-cooling rod 4 passes through the water-cooling chamber 13 and extends to the growth chamber 12. The crucible 6 is located at the center of the inside of the growth chamber 12.

[0025] Specifically, such as Figure 1 , Figure 2 , Figure 3 and Figure 4As shown, the crucible 6 rotates at low speed under the control of the servo rotary motor 15. The crucible 6 and the induction coil 10 rise and fall slowly at the same time. By coordinating the rotation and rise of the crucible and the relative movement of the coil, the position of the heating zone and the crystal growth interface always maintain the consistency of the thermal field. This adapts to the changes in heat conduction conditions during the growth process, breaking through the problem of fixed and unadjustable temperature field in traditional PVT devices. This allows the heating temperature field to be accurately reconstructed at different stages of crystal growth.

[0026] Servo rotary motor 15 output shaft speed range 0-20RPM;

[0027] Specifically, such as Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, the device is equipped with a servo rotary motor 15, whose output shaft drives the water-cooled rod 4 and the crucible 6 to achieve stable rotation in the range of 0.1 to 20 RPM. The rotational motion makes the raw material in the crucible 6 more uniformly heated, suppresses non-uniform sublimation caused by local high temperature, prevents the raw material from concentrated sublimation to form polycrystalline nuclei, effectively controls the distortion and dislocations of the crystal growth interface, thereby improving the overall lattice quality and structural integrity of silicon carbide single crystal SiC.

[0028] The crucible 6 descends at a speed of 1.5 mm / h, the threaded lifting seat 14 rises at a speed of 1 mm / h, the top of the growth chamber 12 is sealed with a top cover 8, the top of the top cover 8 has an air hole 9, the upper frame 11 is bolted to the lower frame 1, and the induction coil 10 is welded to the outer wall of the heat-conducting sleeve 7.

[0029] Specifically, such as Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, the crucible 6 is mounted on the threaded lifting seat 14, which is driven by the screw 2 driven by the geared motor 3, causing the crucible 6 to descend slowly at a speed of 1 mm / h. At the same time, the induction coil 10 is fixedly coiled around the outer wall of the growth chamber 12 and is driven by the growth chamber 12 to rise at a speed of 1.5 mm / h through the servo lifting mechanism. Since the axial movement directions of the crucible 6 and the induction coil 10 are opposite and synchronously controlled, the growth area is continuously within the optimal temperature gradient zone, and the sublimation gas smoothly migrates from the raw material area to the seed crystal area, effectively reducing the formation of the recrystallization zone.

[0030] Working principle: The crucible 6 is mounted on the threaded lifting seat 14, which is driven by the screw 2 driven by the geared motor 3, causing the crucible 6 to descend slowly at a speed of 1 mm / h. At the same time, the induction coil 10 is fixedly coiled around the outer wall of the growth chamber 12 and is driven by the growth chamber 12 to rise at a speed of 1.5 mm / h through the servo lifting mechanism. Since the axial movement directions of the crucible 6 and the induction coil 10 are opposite and synchronously controlled, the growth area is continuously within the optimal temperature gradient zone, and the sublimation gas smoothly migrates from the raw material area to the seed crystal area, effectively reducing the formation of recrystallization zone. The device is equipped with a servo rotary motor 15, whose output shaft drives the water-cooled rod 4 and the crucible 6 at 0. Stable rotation is achieved within a range of 1–20 RPM. The rotational motion makes the raw material in crucible 6 more uniformly heated, suppresses non-uniform sublimation caused by local high temperature, prevents the formation of polycrystalline nuclei due to concentrated sublimation of raw material, and effectively controls the distortion and dislocations at the crystal growth interface. This improves the overall lattice quality and structural integrity of silicon carbide single crystal SiC. The crucible 6 and the induction coil 10 are staggered in height and position. Under the control of the servo rotary motor 15, the crucible 6 rotates at a low speed simultaneously. By coordinating and controlling the movement speed of the two, the position of the heating zone and the crystal growth interface are kept consistent with the thermal field. This adapts to the changes in heat conduction conditions during the growth process, allowing the heating temperature field to be accurately reconstructed at different stages of crystal growth.

[0031] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A silicon carbide single crystal growth apparatus, comprising a support frame (1), characterized in that: The upper frame (11) is fixedly connected to the top of the lower frame (1). A servo lifting mechanism is provided inside the lower frame (1). The servo lifting mechanism includes a geared motor (3) fixedly connected to the top of the lower frame (1). The output shaft of the geared motor (3) is fixedly connected to a screw (2). The screw (2) is movably assembled inside the lower frame (1). A threaded lifting seat (14) and a lifting platform (16) are movably connected to the outside of the screw (2). A water-cooling cavity (13) is fixedly connected to the left side of the threaded lifting seat (14). A growth cavity (12) is connected to the top of the water-cooling cavity (13). A heat-conducting sleeve (7) is covered on the outer wall of the growth cavity (12). An induction coil (10) is wound around the outer wall of the heat-conducting sleeve (7). The top of the lifting platform (16) is equipped with a servo rotation mechanism; the servo rotation mechanism includes a set of servo rotation motors (15) fixed to the top of the lifting platform (16), the output shaft of the servo rotation motors (15) is fixedly connected to a water-cooled rod (4), the top of the water-cooled rod (4) is fixedly connected to a connector (5), and the water-cooled rod (4) is fixedly connected to a crucible (6) through the connector (5).

2. The silicon carbide single crystal growth apparatus according to claim 1, characterized in that: The water-cooling rod (4) penetrates the water-cooling cavity (13) and extends to the growth cavity (12), and the crucible (6) is located at the center of the growth cavity (12).

3. The silicon carbide single crystal growth apparatus according to claim 1, characterized in that: The output shaft speed range of the servo rotary motor (15) is 0-20 RPM.

4. The silicon carbide single crystal growth apparatus according to claim 1, characterized in that: The crucible (6) descends at a speed of 1.5 mm / h, and the threaded lifting seat (14) rises at a speed of 1 mm / h.

5. The silicon carbide single crystal growth apparatus according to claim 1, characterized in that: The top of the growth chamber (12) is sealed with a top cover (8), and the top of the top cover (8) has an air hole (9).

6. The silicon carbide single crystal growth apparatus according to claim 1, characterized in that: The upper frame (11) and the lower frame (1) are bolted together, and the induction coil (10) is welded to the outer wall of the heat-conducting sleeve (7).

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