Silicon carbide single crystal growth equipment with adjustable crucible position

Abstract

The utility model discloses silicon carbide single crystal growth equipment with adjustable crucible position, which comprises a furnace body, a thermal insulation layer, a crucible and a heater, the crucible and the heater are arranged in the thermal insulation layer, the crucible comprises a crucible body and a crucible cover, and the silicon carbide single crystal growth equipment also comprises a crucible lifting device arranged at the bottom of the crucible body. The crucible lifting device is arranged at the bottom of the crucible, so that the crucible can move up and down as required, and the crucible can be positioned at a proper position in a thermal field generated by the heater according to the change of a crystal growth interface of the silicon carbide single crystal, so as to meet the requirements of a crystal growth process.

Description

Technical Field

[0001] This utility model relates to the field of silicon carbide semiconductor technology, and in particular to a silicon carbide single crystal growth device with an adjustable crucible position. Background Technology

[0002] Silicon carbide (SiC) single crystal, as an important third-generation wide-bandgap semiconductor material, has broad application prospects in power electronic devices used under extreme conditions such as high frequency, high power, radiation resistance, corrosion resistance, and high temperature resistance due to its advantages such as wide bandgap, high thermal conductivity, high critical breakdown electric field and high electron saturation migration rate.

[0003] Physical vapor transport (PVT) is a commonly used method for growing silicon carbide single crystals. It involves placing polycrystalline silicon carbide material at the bottom of a cylindrical graphite crucible, covering it with a graphite crucible lid to form a sealed space. A silicon carbide seed crystal is mounted on the lower surface of the lid. By heating the system consisting of the crucible and lid, the polycrystalline silicon carbide material inside the crucible sublimates, maintaining a suitable temperature gradient between the material and the seed crystal. The sublimated silicon carbide particles then deposit and grow on the seed crystal, thus obtaining a silicon carbide single crystal.

[0004] Silicon carbide single crystal growth equipment mainly includes an insulation layer inside the furnace, a crucible located within the insulation layer, and a heater positioned between the insulation layer and the crucible. The heater heats the crucible, melting the silicon carbide source powder inside, causing it to sublimate and recrystallize at the silicon carbide seed crystal located at the bottom of the crucible's top cover, thus obtaining a silicon carbide single crystal. The heater is typically positioned around the crucible to ensure uniform heating. However, because the heater is fixed inside the furnace, the required temperature gradient between the polycrystalline silicon carbide raw material and the silicon carbide seed crystal leads to temperature variations in different areas within the crucible. The growth interface of the silicon carbide single crystal constantly changes, especially during the processing of large-size single crystals. When the growth interface changes to other areas, the temperature may not be suitable for the crystal growth process. Current technology only allows changing the temperature of different areas by varying the heater power to meet the crystal growth process requirements. However, this method cannot precisely adjust the temperature of the growth interface, easily leading to quality problems such as uneven growth interfaces and numerous crystal dislocation microtube defects. Utility Model Content

[0005] The technical problem to be solved by this utility model is that the temperature at the changing crystal growth interface in the existing silicon carbide single crystal growth equipment is difficult to control precisely, resulting in an uneven crystal growth interface and a large number of crystal dislocation microtube defects. The present invention provides a silicon carbide single crystal growth equipment with an adjustable crucible position that can change the crucible position according to the change of the crystal growth interface, thereby maintaining a consistent crystal growth temperature gradient.

[0006] The technical solution to this problem is: to construct a silicon carbide single crystal growth device with adjustable crucible position, including a furnace body, a heat insulation layer, a crucible and a heater disposed in the heat insulation layer, the crucible including a crucible body and a crucible cover, and a crucible lifting device disposed at the bottom of the crucible body.

[0007] Furthermore, the furnace body includes a lower furnace cover that is sealed at the lower opening of the furnace body, and the crucible lifting device includes a lifting guide rod disposed at the bottom of the crucible body that passes through the insulation layer and the lower furnace cover, and a driver disposed at the bottom of the furnace body that drives the lifting guide rod to rise and fall.

[0008] Furthermore, the driver includes a first drive motor disposed at the bottom of the lower furnace cover, a first lead screw driven by the first drive motor, and a first slider sleeved on the first lead screw, the first slider being fixed to the bottom side of the lifting guide rod.

[0009] A positioning frame is fixedly provided at the bottom of the lower furnace cover, the first lead screw is vertically rotatably mounted on the positioning frame, and the first drive motor is located at the bottom end of the positioning frame.

[0010] Furthermore, it also includes a control system, which is electrically connected to the first drive motor. The control system controls the first drive motor to drive the lifting guide rod to rise and fall according to a preset program. Thus, the lifting guide rod can be automatically controlled according to the calculated position change of the crystal growth interface to ensure that the crystal growth interface of the seed crystal is always located in the area of ​​the crucible that meets the process temperature, thereby further ensuring the growth quality of silicon carbide single crystal.

[0011] Furthermore, the bottom of the lower furnace cover is provided with a shaft hole that matches the lifting guide rod, and a sliding sealing bushing is provided between the shaft hole and the lifting guide rod; this further ensures the airtightness of the furnace body.

[0012] Furthermore, the insulation layer includes a lower movable insulation block, and the insulation layer has a lower opening that matches the lower movable insulation block. The lower movable insulation block is fixed to the top of the lower furnace cover, and the lifting guide rod passes through the lower movable insulation block. This allows the lower movable insulation block to rise and fall together with the lower furnace cover, ensuring the thermal sealing of the internal space of the insulation layer without affecting the lifting and lowering of the crucible.

[0013] Furthermore, the heater includes an upper heating element disposed around the crucible and a lower heating element disposed at the bottom of the crucible body. The upper heating element is fixedly disposed on the inner wall of the furnace body, and the lower heating element is fixedly disposed on the top side of the lower furnace cover. This allows for rapid melting of the silicon carbide polycrystalline raw material at the bottom of the crucible body, thereby improving production efficiency.

[0014] Furthermore, it also includes a furnace frame for fixing the furnace body, on which a lower furnace cover lifting device is provided. The lower furnace cover lifting device includes a second lead screw vertically rotatably mounted on the furnace frame, a second slider sleeved on the second lead screw, and a second drive motor mounted on the furnace frame to drive the second lead screw to rotate. The second slider is fixed to the outside of the lower furnace cover by a connecting rod. This facilitates mechanized operation of the lower furnace cover and crucible, speeds up the furnace opening process, and improves production efficiency.

[0015] Furthermore, the control system is electrically connected to the second drive motor, and the control system controls the second drive motor to drive the lower furnace cover to open and close at the lower end of the furnace body; this facilitates automated operation of furnace opening and loading, further improving production efficiency.

[0016] The silicon carbide single crystal growth equipment with adjustable crucible position described in this invention has the following beneficial effects: By setting a crucible lifting device at the bottom of the crucible, the crucible can be moved up and down as needed, ensuring that the crucible is positioned appropriately within the thermal field generated by the heater according to the changes in the growth interface of the silicon carbide single crystal, thus meeting the requirements of the crystal growth process. Specifically, by setting the crucible lifting device, which includes a lifting guide rod at the bottom of the crucible body and a driver for driving the lifting guide rod up and down, the position of the growth interface can be determined based on the calculated growth speed and the initial position of the silicon carbide seed crystal on the crucible cover. Then, the crucible position matching the growth interface is determined based on the position of the temperature gradient inside the crucible. The driver precisely controls the rising speed and initial position of the crucible, thereby ensuring the growth quality of the silicon carbide single crystal. Attached Figure Description

[0017] Figure 1 The diagram shown is a preferred embodiment of the silicon carbide single crystal growth equipment of this utility model.

[0018] Figure 1a As shown Figure 1 Enlarged schematic diagram of Part I;

[0019] Figure 1b As shown Figure 1 Enlarged schematic diagram of Part II;

[0020] Figure 2 The diagram shown is a schematic representation of the structure of the silicon carbide single crystal growth equipment with adjustable crucible position according to the present invention when the crucible is lifted.

[0021] Figure 3 The diagram shown is a schematic representation of the structure of the silicon carbide single crystal growth equipment with adjustable crucible position according to the present invention when the lower furnace cover is opened. Detailed Implementation

[0022] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] It should also be noted that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0025] like Figure 1 , 1a As shown in Figures 1b, 2, and 3, in a preferred embodiment of the silicon carbide single crystal growth equipment of this utility model, the equipment mainly includes a furnace body 10, an insulation layer 20, a crucible 30, and a heater 40. The furnace body 10 may include a lower furnace cover 11 as needed. Specifically, an opening 12 may be provided at the lower end of the furnace body 10, and the lower furnace cover 11 matches the opening 12 to seal it. Sealing fasteners are provided around the lower furnace cover 11 to tightly seal it at the opening 12. After removing the lower furnace cover 11, the furnace body 10 can be quickly opened. Before preparing silicon carbide single crystals, the silicon carbide polycrystalline raw material 3 is placed into the crucible 30, and the silicon carbide seed crystal 1 is installed inside the crucible 30. Simultaneously, the lower furnace cover 11 is reliably sealed to the furnace body 10, ensuring that the space inside the furnace body 10 is airtight during the preparation process, preventing contamination of the silicon carbide inside the furnace body 10. The insulation layer 20 is uniformly attached to the inner wall of the furnace body 10, forming an insulation cavity 23 inside the furnace body 10. The crucible 30 and the heater 40 are disposed within the insulation cavity 23, with the heater 40 located between the crucible 30 and the insulation layer 20. When the crucible 30 is heated by the heater 40, the polycrystalline silicon carbide raw material 3 inside the crucible 30 is sublimated into fumed silicon carbide. The fumed silicon carbide gradually cools and recrystallizes at the silicon carbide seed crystal 1, forming a silicon carbide single crystal.

[0026] In this preferred embodiment, the crucible 30 includes a crucible body 31 and a crucible cover 32, and also includes a crucible lifting device 50 disposed at the bottom of the crucible body 31, used to drive the crucible 30 up and down to adjust the height position of the crucible 30 within the insulation cavity 23, so that the growth interface of the silicon carbide seed crystal 1 located at the bottom of the crucible cover 32 is always within the temperature range required by the process. Preferably, the crucible lifting device 50 includes a lifting guide rod 51 and a driver 52, wherein one end of the lifting guide rod 51 is fixedly connected to the bottom of the crucible body 31, and the other end passes vertically through the insulation layer 20 and the lower furnace cover 11 and is connected to the driver 52, which can drive the lifting guide rod 51 up and down. Specifically, preferably, a shaft hole 13 matching the lifting guide rod 51 is provided on the lower furnace cover 11, and a sliding sealing bushing 14 is provided between the shaft hole 13 and the lifting guide rod 51. The sliding sealing bushing 14 is embedded in the shaft hole 13, and the lifting guide rod 51 is slidably disposed in the sliding sealing bushing 14.

[0027] In this preferred embodiment, the driver 52 preferably includes a first drive motor 53, a first lead screw 54, and a first slider 55. The first drive motor 53 is located at the bottom of the lower furnace cover 11 and can be a servo motor or a frequency converter motor. The first lead screw 54 is vertically rotatable at the bottom of the lower furnace cover 11 and is driven by the first drive motor 53. The first slider 55 is sleeved on the first lead screw 54 and fixed to the bottom side of the lifting guide rod 51. Specifically, the first drive motor 53 can be located at the end of the first lead screw 54, and a threaded hole 56 matching the first lead screw 54 can be provided at the center of the first slider 55. When the first drive motor 53 drives the first lead screw 54 to rotate forward and backward, the first slider 55 can move up and down along the first lead screw 54, thereby driving the lifting guide rod 51 to move up and down within the sliding sealing sleeve 14, causing the crucible 30 located at the top of the lifting guide rod to also move up and down accordingly. Ideally, a positioning frame 57 should be fixedly installed at the bottom of the lower furnace cover 11, with the first lead screw 54 vertically rotating on the positioning frame 57, and the first drive motor 53 installed at the bottom of the positioning frame 57.

[0028] Preferably, the insulation layer 20 includes a lower movable insulation block 21. A lower opening 22 matching the lower movable insulation block 21 is formed at the bottom of the insulation layer 20. The maximum outline size of the lower opening 22 is set larger than the maximum outline size of the crucible 30 so that the crucible 30 can be inserted or removed through the lower opening 22 after the lower furnace cover 11 is opened. The lower movable insulation block 21 can be fixedly set on the top of the lower furnace cover 11, and the aforementioned lifting guide rod 51 passes through the lower movable insulation block 21.

[0029] In this preferred embodiment, the heater 40 preferably includes an upper heating element 41 and a lower heating element 42. The upper heating element 42 is preferably disposed around the crucible 30 to heat the crucible body 31, allowing the silicon carbide polycrystalline raw material 3 inside the crucible to sublimate into fumed silicon carbide. Specifically, the upper heating element 41 can be fixed to the inner wall of the furnace body 10 via a connector. The lower heating element 42 is disposed at the bottom of the crucible body 31 to heat the silicon carbide polycrystalline raw material 3 at the bottom inner side of the crucible body, allowing the raw material to melt rapidly and sublimate into fumed silicon carbide, thereby improving production efficiency. Specifically, the lower heating element 42 can be fixed to the top side of the lower furnace cover 11 via a connector and located between the insulation layer 20 and the crucible body 31.

[0030] In this preferred embodiment, the furnace further includes a furnace frame 15 for fixing the furnace body 10. A lower furnace cover lifting device 60 is provided on the furnace frame 15. This lower furnace cover lifting device 60 can be used to lift the lower furnace cover 11 and the crucible 30, thereby improving the furnace opening speed and production efficiency. Preferably, the lower furnace cover lifting device 60 includes a second lead screw 61, a second slider 62, and a second drive motor 63. The second lead screw 61 is vertically rotatably mounted on the furnace frame 15 and located below the lower furnace cover 11. The second slider 62 is sleeved on the second lead screw 61. The second drive motor 63 is mounted on the furnace frame 15 to drive the second lead screw 61 to rotate. The second slider 62 is fixed to the outside of the lower furnace cover 11 by a connecting rod 64. By driving the second lead screw 61 to rotate forward and backward by the second drive motor 63, the second slider 62 and the lower furnace cover 11 can be lifted up and down, thereby causing the entire crucible lifting device 50 and the crucible 30 to rise and fall accordingly.

[0031] In the above embodiments, a control system is preferably also included, which can be electrically connected to the first drive motor 53. By adjusting the process conditions, the growth speed of silicon carbide can be controlled according to a preset speed, thereby obtaining the position information of the growth interface inside the crucible 30. The control system can automatically control the first drive motor 53 to drive the lifting guide rod 51 to rise and fall according to the position change of the growth interface, thereby driving the crucible 30 to rise and fall, so as to automatically control the growth interface of the silicon carbide seed crystal 1 to always be in the temperature range required by the process, further ensuring the growth quality of the silicon carbide single crystal 2. Similarly, the control system can be electrically connected to the second drive motor 63. When it is necessary to open the lower furnace cover 11, first release the sealing fasteners between the lower furnace cover 11 and the furnace body 10, and then control the second drive motor 63 to drive the second lead screw 61 to rotate through the control system. The second slider 62 drives the lower furnace cover 11 to fall, thereby driving the crucible lifting device 50 and the crucible 30 to fall below the furnace body 10. At this time, the loading or unloading operation can be performed. After the charging or unloading operation is completed, the control system controls the second drive motor 63 to drive the second lead screw 61 to reverse, and the second slider 62 drives the lower furnace cover 11 to rise and seal it to the opening 12 of the furnace body 10.

[0032] In this preferred embodiment, a process gas path system (not shown in the figure) may also be included to control the vacuum level inside the furnace body 10 and to charge the furnace body 10 with process gas; a water cooling system (not shown in the figure) may also be provided as needed to accelerate the cooling rate of the furnace body 10 after the silicon carbide single crystal preparation is completed.

[0033] Based on the embodiments of this utility model, any modifications, equivalent substitutions, improvements, etc., made by all other embodiments obtained by those skilled in the art without creative effort should be included within the protection scope of this utility model.

Claims

1. A silicon carbide single crystal growth apparatus with adjustable crucible position, comprising a furnace body, an insulation layer, a crucible provided in the insulation layer, and a heater, the crucible comprising a crucible body and a crucible lid, characterized in that, The furnace body comprises a lower furnace cover sealingly arranged at the opening of the lower end of the furnace body, and the crucible lifting device comprises a lifting guide rod arranged at the bottom of the crucible body and penetrating through the heat preservation layer and the lower furnace cover, and a driver arranged at the bottom of the furnace body and driving the lifting guide rod to lift.

2. The apparatus for growing a silicon carbide single crystal according to claim 1, wherein The driver comprises a first driving motor arranged at the bottom of the lower furnace cover, a first screw rod driven by the first driving motor, and a first sliding block sleeved on the first screw rod, the first sliding block being fixed to the bottom side of the lifting guide rod.

3. The apparatus for growing a silicon carbide single crystal with adjustable crucible position according to claim 2, wherein The bottom of the lower furnace cover is fixedly provided with a positioning frame, the first screw rod is vertically arranged on the positioning frame, and the first driving motor is arranged at the bottom end of the positioning frame.

4. The apparatus for growing a silicon carbide single crystal with a position-adjustable crucible according to claim 2, wherein The control system is electrically connected with the first driving motor, and the control system controls the first driving motor to drive the lifting guide rod to lift according to a preset program.

5. The apparatus for growing a silicon carbide single crystal with adjustable crucible position according to claim 1, wherein The lower furnace cover is provided with an axle hole matched with the lifting guide rod, and a sliding sealing sleeve is arranged between the axle hole and the lifting guide rod.

6. The apparatus for growing a silicon carbide single crystal with adjustable crucible position according to claim 1, wherein The heat preservation layer comprises a lower movable heat preservation block, the heat preservation layer is provided with a lower opening matched with the lower movable heat preservation block, the lower movable heat preservation block is fixed to the top of the lower furnace cover, and the lifting guide rod penetrates through the lower movable heat preservation block.

7. The apparatus for growing a silicon carbide single crystal with a position-adjustable crucible according to claim 1, wherein The heater comprises an upper heating body arranged around the crucible and a lower heating body arranged at the bottom of the crucible body, the upper heating body is fixedly arranged on the inner side wall of the furnace body, and the lower heating body is fixedly arranged on the top side of the lower furnace cover.

8. The apparatus for growing a silicon carbide single crystal according to claim 6 or 7, wherein The furnace frame is further provided with a lower furnace cover lifting device, the lower furnace cover lifting device comprises a second screw rod vertically arranged on the furnace frame, a second sliding block sleeved on the second screw rod, and a second driving motor arranged on the furnace frame and driving the second screw rod to rotate, and the second sliding block is fixed to the outer side of the lower furnace cover through a connecting rod.

9. The apparatus for growing a silicon carbide single crystal with a position-adjustable crucible according to claim 8, wherein The control system is electrically connected with the second driving motor, and the control system controls the second driving motor to drive the lower furnace cover to open and close at the opening of the lower end of the furnace body.

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