A crucible structure for single crystal growth with low stress and low dislocation

Abstract

The utility model belongs to the field of silicon carbide single crystal production, and specifically relates to a crucible structure for single crystal growth with low stress and low dislocation, comprising a crucible, wherein a graphite blocking sheet for separating upper and lower cavities is arranged on the crucible, a graphite blocking ring is arranged above the graphite blocking sheet, a graphite spoiler ring is arranged in a clamping interval between the two, and a crucible cover is placed on the upper part of the graphite spoiler ring; a combined mechanism comprises an upper ring pad formed on the crucible cover and a lower ring pad on the graphite spoiler ring, bolt holes are symmetrically provided on the upper ring pad and the lower ring pad, and bolt rods are connected in the bolt holes; the lifting mechanism works to drive the crucible cover to move upward, thereby increasing the space of the growth cavity, while ensuring the sealing, making Si, Si2C, SiC2 and other gas phase components still in the growth cavity, and always being in a low temperature state for crystallization, because the seed crystal is always in the axial position, dislocation of crystallization is prevented, and the growth thickness increases due to the lifting of the space, thereby reducing the crystallization stress.

Description

Technical Field

[0001] The utility model relates to the field of silicon carbide single crystal production, in particular to a crucible structure for single crystal growth with low stress and low dislocation. Background Art

[0002] Silicon carbide single crystal is a new third-generation semiconductor material for preparing radio frequency power devices and high-voltage power electronic devices. Currently, the mainstream silicon carbide single crystal growth method in the world is physical vapor transport method.

[0003] The physical vapor transport method for growing silicon carbide single crystals generally adopts induction heating. In a graphite crucible protected by an inert gas atmosphere, silicon carbide powder is used as the raw material. Under a certain temperature and pressure, the solid silicon carbide powder at the bottom of the graphite crucible sublimates and decomposes at high temperature to form gas phase components such as Si(g), Si2C(g), and SiC2(g). Due to the temperature gradient in the axial direction of the graphite crucible reaction chamber, the sublimated and decomposed gas phase components move from the relatively high temperature growth raw material area to the relatively low temperature growth interface, and deposit and crystallize on the silicon carbide seed crystal at the top of the graphite crucible. This process lasts for a certain period of time, and the growth interface will steadily move toward the raw material area, and finally generate a silicon carbide single crystal of a certain thickness.

[0004] Silicon carbide single crystal grows at the bottom of the crucible cover, but the space at the bottom of the crucible cover is fixed. The movement of sublimated and decomposed gas components from the relatively high-temperature growth raw material area to the relatively low-temperature growth interface is hindered by crystallization, causing the subsequently generated crystals to block the channel. In addition, due to the reduction of the growth space, the temperature increase will affect the quality of crystal growth. Utility Model Content

[0005] (I) Purpose of the utility model

[0006] In order to solve the technical problems existing in the background technology, the utility model proposes a low-stress and low-dislocation crucible structure for single crystal growth, which has the characteristics of adjustable single crystal growth space, ensuring sufficient growth space and ensuring the quality of single crystal growth.

[0007] (II) Technical solution

[0008] In order to solve the above technical problems, the utility model provides a low-stress and low-dislocation single crystal growth crucible structure, comprising a crucible, on which a graphite barrier sheet is provided to separate the upper and lower cavities.

[0009] A graphite blocking ring is arranged above the graphite blocking sheet, a graphite spoiler ring is arranged in the clamping interval between the two, and a crucible cover is placed on the upper part of the graphite spoiler ring;

[0010] The combined mechanism comprises an upper ring gasket formed on the crucible cover and a lower ring gasket on the graphite spoiler ring, bolt holes are symmetrically arranged on the upper ring gasket and the lower ring gasket, and bolt rods are connected in the bolt holes;

[0011] The heating mechanism comprises an inner heater arranged in the lower cavity of the crucible, a lower heater with an annular structure is arranged on the outer side of the crucible, and an upper heater with an annular structure is arranged on the outer side of the upper cavity of the crucible;

[0012] The lifting mechanism comprises a cylinder arranged at one side of the crucible, a piston rod is installed at the output end of the cylinder, and the piston rod is connected to the crucible cover through a connecting rod.

[0013] Preferably, the lower cavity of the crucible separated by the graphite barrier sheet is a raw material cavity, and the upper cavity is a growth cavity.

[0014] Preferably, a seed crystal is bonded to the bottom of the crucible cover, and the seed crystal is parallel to the opening of the graphite blocking sheet.

[0015] Preferably, the connecting rod is an "inverted U-shaped" structure, and the seed crystal and the crucible cover are displaced synchronously.

[0016] Preferably, the crucible cover and the graphite spoiler ring are connected via a combined mechanism, and when the crucible cover moves, the end surface attached to the graphite blocking ring is in a sealed state.

[0017] Preferably, the outer sides of the lower heater and the upper heater are covered with thermal insulation covers.

[0018] The above-mentioned technical scheme of the utility model has the following beneficial technical effects: through the operation of the lifting mechanism, the crucible cover is driven to move upward, thereby increasing the space of the growth cavity. While ensuring the sealing, the gas phase components such as Si, Si2C, SiC2 are still in the growth cavity, and are always crystallized in a low temperature state. Because the seed crystal is always in the axial position, dislocation of crystallization is prevented, and the growth thickness is increased due to the lifting of the space, which can reduce the crystallization stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the utility model;

[0020] Figure 2 It is a cross-sectional structural schematic diagram of the utility model;

[0021] Figure 3 It is a schematic diagram of the implementation of the utility model.

[0022] Reference numerals:

[0023] 1. Crucible; 21. Graphite blocking plate; 22. Graphite blocking ring; 23. Graphite spoiler ring; 24. Crucible cover; 31. Upper ring gasket; 32. Lower ring gasket; 33. Bolt rod; 41. Inner heater; 42. Lower heater; 43. Upper heater; 51. Cylinder; 52. Piston rod; 53. Connecting rod; 6. Seed crystal; 7. Insulation sleeve. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model is further described in detail below in combination with specific implementation methods and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the utility model. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the utility model.

[0025] like Figure 1-3 As shown, the utility model proposes a low-stress and low-dislocation single crystal growth crucible structure, comprising a crucible 1, on which a graphite barrier sheet 21 is provided to separate the upper and lower cavities.

[0026] A graphite blocking ring 22 is arranged above the graphite blocking sheet 21, a graphite spoiler ring 23 is arranged in the clamping interval between the two, and a crucible cover 24 is placed on the upper part of the graphite spoiler ring 23;

[0027] The combined mechanism includes an upper ring gasket 31 formed on the crucible cover 24 and a lower ring gasket 32 ​​on the graphite spoiler ring 23. Bolt holes are symmetrically provided on the upper ring gasket 31 and the lower ring gasket 32, and bolt rods 33 are connected to the bolt holes.

[0028] The heating mechanism comprises an inner heater 41 arranged in the lower cavity of the crucible 1, a lower heater 42 with an annular structure is arranged on the outer side of the crucible 1, and an upper heater 43 with an annular structure is arranged on the outer side of the upper cavity of the crucible 1;

[0029] The lifting mechanism includes a cylinder 51 disposed on one side of the crucible 1 . A piston rod 52 is mounted on the output end of the cylinder 51 . The piston rod 52 is connected to the crucible cover 24 via a connecting rod 53 .

[0030] It should be noted that the lower cavity of the crucible 1 separated by the graphite blocking sheet 21 is the raw material cavity, in which silicon carbide powder is placed, the upper cavity is the growth cavity, and a seed crystal 6 is bonded to the bottom of the crucible cover 24. The seed crystal 6 is parallel to the opening of the graphite blocking sheet 21. The gas sublimated by the heating of the silicon carbide powder enters the growth cavity through the opening, and crystal growth is carried out at the position of the seed crystal 6.

[0031] In this embodiment, the silicon carbide powder is sublimated and decomposed into gas phase components such as Si, Si2C, and SiC2 through the operation of the heating mechanism, diffused through the graphite spoiler ring 23, and transmitted to the surface of the SiC seed crystal 6 in the low temperature zone of the growth chamber, and crystallized into a silicon carbide single crystal. During the growth process, the space of the growth chamber is affected by the crystallization, and the temperature in the low temperature zone rises, resulting in a decrease in the crystallization effect.

[0032] Through the operation of the lifting mechanism, the cylinder 51 drives the piston rod 52 to extend, driving the crucible cover 24 to move upward. Since the growth chamber is surrounded by the graphite spoiler ring 23, the graphite blocking ring 22 and the graphite blocking sheet 21, the crucible cover 24 and the graphite spoiler ring 23 are connected by a combined mechanism. When the crucible cover 24 moves, the end surface attached to the graphite blocking ring 22 is in a sealed state. The rising crucible cover 24 ensures the sealing of the growth chamber while keeping the gas phase components such as Si, Si2C, SiC2 in the growth chamber. The growth chamber is always in a low temperature state for crystallization.

[0033] It can be understood that the connecting rod 53 is an "inverted U-shaped" structure, which drives the crucible cover 24 to move upward, and the seed crystal 6 and the crucible cover 24 are displaced synchronously. Since the seed crystal 6 is always in the axial position, dislocation of crystallization is prevented, and the growth thickness increases due to the space increase, which can reduce the crystallization stress.

[0034] like Figure 2 As shown, the heating mechanism includes an inner heater 41 arranged in the lower cavity of the crucible 1, and a lower heater 42 with an annular structure is arranged on the outer side of the crucible 1. The inner heater 41 located inside and the lower heater 42 located outside heat the silicon carbide powder at the same time, so that the center position of the silicon carbide powder can be heated more fully, thereby improving the utilization rate of the silicon carbide powder.

[0035] An upper heater 43 of an annular structure is arranged outside the upper cavity of the crucible 1. The heating temperature of the upper heater 43 is lower than that of other heaters, so as to make the rising gas phase components crystallize at low temperature.

[0036] By controlling the upper heater 43, the lower heater 42 and the inner heater 41, the radial temperature and axial temperature gradient inside the crucible can be adjusted, and the Si / C ratio of the gas phase components can be adjusted, so as to grow thicker and better quality crystals.

[0037] Among them, after the space in the growth chamber is increased, the upper heater 43 is still in the initial position, the previously crystallized silicon carbide single crystal is equivalent to the seed crystal 6, and the growth space is still maintained at a low temperature through the heat release of the upper heater 43.

[0038] In order to improve the heat preservation effect of the crucible 1 , further, the outer sides of the lower heater 42 and the upper heater 43 are covered with heat preservation sleeves 7 .

[0039] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation on the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the claims attached to the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the attached claims, or the equivalent forms of such scope and boundaries.

Claims

1. A crucible structure for single crystal growth with low stress and low dislocation, characterized in that: The crucible (1) comprises a graphite barrier sheet (21) for separating an upper cavity and an lower cavity. A graphite blocking ring (22) is arranged above the graphite blocking sheet (21), a graphite spoiler ring (23) is arranged in the clamping area between the two, and a crucible cover (24) is placed on the upper part of the graphite spoiler ring (23); The combined mechanism comprises an upper ring gasket (31) formed on the crucible cover (24) and a lower ring gasket (32) on the graphite spoiler ring (23), bolt holes are provided at symmetrical positions on the upper ring gasket (31) and the lower ring gasket (32), and bolt rods (33) are connected to the bolt holes; The heating mechanism comprises an inner heater (41) arranged in the lower cavity of the crucible (1), a lower heater (42) with an annular structure is arranged on the outer side of the crucible (1), and an upper heater (43) with an annular structure is arranged on the outer side of the upper cavity of the crucible (1); The lifting mechanism comprises a cylinder (51) arranged on one side of the crucible (1), a piston rod (52) is installed at the output end of the cylinder (51), and the piston rod (52) is connected to the crucible cover (24) through a connecting rod (53).

2. The crucible structure for single crystal growth with low stress and low dislocation according to claim 1, characterized in that: The lower cavity of the crucible (1) separated by the graphite blocking sheet (21) is a raw material cavity, and the upper cavity is a growth cavity.

3. The crucible structure for single crystal growth with low stress and low dislocation according to claim 1, characterized in that: A seed crystal (6) is bonded to the bottom of the crucible cover (24), and the seed crystal (6) is parallel to the opening of the graphite blocking sheet (21).

4. The crucible structure for single crystal growth with low stress and low dislocation according to claim 3, characterized in that: The connecting rod (53) is an "inverted U-shaped" structure, and the seed crystal (6) and the crucible cover (24) move synchronously.

5. The crucible structure for single crystal growth with low stress and low dislocation according to claim 1, characterized in that: The crucible cover (24) and the graphite spoiler ring (23) are connected via a combined mechanism, and when the crucible cover (24) moves, the end surface attached to the graphite blocking ring (22) is in a sealed state.

6. The crucible structure for single crystal growth with low stress and low dislocation according to claim 1, characterized in that: The outer sides of the lower heater (42) and the upper heater (43) are covered with heat-insulating covers (7).

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