Device and method for growing silicon carbide single crystal based on PVT method

1 . A device for growing a silicon carbide single crystal based on a PVT method, comprising a growth chamber, a crucible, and a stock bin for holding raw materials, wherein the crucible and the stock bin are located in the growth chamber, and the stock bin is located in the crucible, wherein the stock bin comprises independent storage compartments, and the device further comprises one or more lifting rods, wherein each of the lifting rods is located in the growth chamber, extends from a bottom of the crucible, passes through a bottom of one of the storage compartments, and extends to a top of the storage compartment, wherein the lifting rod moves upward and downward to seal the storage compartment, or creating a channel for gas-phase raw materials transmission at the top of the storage compartment.

2 . The device according to claim 1 , wherein an exhaust hole is located at the top of each storage compartment and serves as the channel for gas-phase raw materials transmission, wherein a top of each lifting rod is provided with an end surface matching the corresponding exhaust hole, wherein when the lifting rod moves upward and the end surface of the lifting rod abuts the exhaust hole, the storage compartment is sealed, and wherein when the lifting rod moves downward and the end surface of the lifting rod is away from the exhaust hole, gas-phase raw materials are discharged from the storage compartment through the exhaust hole.

3 . The device according to claim 2 , wherein a diameter of each exhaust hole ranges from 0.1 mm to 5 mm, and a lower portion of each exhaust hole is provided with a conical surface that matches the end surface of the corresponding lifting rod, with a conical angle of the conical surface ranging from 5° to 85°.

4 . The device according to claim 3 , wherein a frustum with a height of 1 mm to 5 mm and a diameter of 1 mm to 10 mm is located at the top of each lifting rod, and the frustum is connected with the end surface of the lifting rod.

5 . The device according to claim 1 , wherein each storage compartment is sealed by a graphite thin cover and/or several layers of graphite paper, with a thickness of the graphite thin cover ranging from 0.1 mm to 2 mm, and the lifting rod moves upward to form a hole in the graphite thin cover and/or the several layers of graphite paper, creating the channel for gas-phase raw materials transmission.

6 . The device according to claim 5 , wherein an end surface of each lifting rod is arc-shaped, and a roughness of the end surface is not greater than 1.6 μm.

7 . The device according to claim 1 , wherein the storage compartments of the stock bin are concentric circular structures or concentric polygonal structures arranged inside the crucible based on their inner diameters;

or,

planar shapes of the storage compartments comprise one or more of triangles, quadrilaterals, hexagons, and circles, and the storage compartments are arranged in a honeycomb pattern.

8 . The device according to claim 1 , wherein a top of the stock bin has a parabolic structure with a lower middle and higher edges.

9 . The device according to claim 1 , wherein a thickness of a sidewall of the crucible ranges from 5 mm to 25 mm, and a thickness of a sidewall of each of the storage compartments ranges from 0.5 mm to 3 mm; wherein each lifting rod is a graphite rod with a diameter of 2 mm to 15 mm.

10 . The device according to claim 1 , wherein the bottom of the crucible is provided with threaded holes, and each of the lifting rods is arranged in one of the threaded holes and is threadedly engaged with the threaded hole; wherein each lifting rod is configured to move upward and downward by adjusting a thread engagement length of the lifting rod within the threaded hole.

11 . A method for growing a silicon carbide single crystal based on a PVT method, comprising:

S1: providing a device according to claim 1 , and further configuring the device such that a holder where a silicon carbide seed crystal is fixed is located in the growth chamber and above the stock bin, the raw materials are stored in the storage compartments, and each of the one or more lifting rods extends from the bottom of the crucible, passes through one of the storage compartments, and extends to the top of the storage compartment, keeping the storage compartment sealed;

S2: placing the crucible in a thermal field, and when the thermal field reaches a preset temperature and pressure, moving some of the lifting rods near an edge of the stock bin to release gas-phase raw materials through exhaust holes of a first subset of the storage compartments, causing a surface of the silicon carbide seed crystal to begin nucleating stably for a first period;

S3: moving other ones of the lifting rods near a center of the stock bin to release gas-phase raw materials through exhaust holes of a second subset of the storage compartments, causing the surface of the silicon carbide seed crystal to continue nucleating stably for a second period; and

S4: repeating steps S2 and S3 until the gas-phase raw materials in the storage compartments are completely released, completing growth of the silicon carbide single crystal.

12 . The method according to claim 11 , wherein when using a silicon carbide seed crystal with an offset angle greater than 2° between a C-plane [0001] and an A-plane [11 2 0], amounts of the raw materials in different storage compartments are adjusted to selectively reduce gas-phase raw materials released from those of the storage compartments below the C-plane, enabling the silicon carbide seed crystal to grow with a non-axisymmetric concentration under an axisymmetric temperature distribution.

13 . The method according to claim 11 , wherein after the crucible is placed in the thermal field, an initial atmosphere in the thermal field is at a pressure of 500 mbar to 800 mbar, then the crucible is heated and stays at 2200° C.-2450° C. for 30 min to 5 h, and the pressure is reduced to 0.5 mbar to 50 mbar over a period of 1 h to 15 h; wherein the first period and the second period are both 5 h to 50 h; wherein after the growth of the silicon carbide single crystal is completed, the pressure of the thermal field is adjusted to 100 mbar to 600 mbar, a heating power is reduced to zero over 5 h to 10 h, and the crucible is naturally cooled to room temperature before removing the silicon carbide single crystal.

14 . The method according to claim 11 , wherein the silicon carbide single crystal is greater than or equal to 8 inches, and a thickness of the silicon carbide single crystal is greater than or equal to 15 mm.