TW201829860A - Crucible and manufacture method thereof, and 4h-sic crystal growth method - Google Patents

Abstract

This invention provides a crucible and a manufacture method thereof, and a 4H-SiC crystal growth method. The crucible comprises a carbon graphite crucible; a SiC layer deposited on an inner surface of the carbon graphite crucible. Via the SiC layer, the SiC layer can be used as a carbon source or a silicon source for the 4H-SiC crystal growth. the purity of the crucible is enough, and the cost of the crucible is less than that of SiC crucible.

Description

   Crucible, method for preparing crucible, and method for growing silicon carbide crystal (4H-SiC)   

The invention belongs to the technical field of crystal growth, and particularly relates to a crucible, a method for preparing the crucible, and a method for growing silicon carbide crystal (4H-SiC).

In the prior art, the growth methods of silicon carbide crystals (4H-SiC) mainly include TSM (Traveling Solvent Method), SCT (Slow Cooling Technique, slow cooling method), VLS (Vapor Liquid Solid, vapor liquid solid Growth method) and TSSG (Top Seeded Solution Growth).

The equipment for growing silicon carbide crystals (4H-SiC) by the TSSG method is shown in FIG. 1 and includes a crystal growth furnace 10; a support frame 11 is located in the crystal growth furnace 10 and is located at the bottom of the crystal growth furnace 10; A graphite crucible 12 is located in the crystal growth furnace 10 and is located on the top of the support frame 11; a base 15 is located in the crystal growth furnace 10 and is located around the graphite crucible 12; a heat insulation layer 16 Is located in the crystal growth furnace 10 and is located around the base 15; heater 17 is located in the crystal growth furnace 10 and is located around the heat insulation layer 16. When using the above equipment to grow silicon carbide crystals (4H-SiC) by the TSSG method, the seed crystal 13 is placed on the bottom of the graphite crucible 12, and the carbon source and silicon source 14 are placed in the graphite crucible 12, using the The heater 17 heats the carbon source and the silicon source 14 to melt into a liquid. When the temperature is suitable, silicon carbide crystals (4H-SiC) are formed on the surface of the seed crystal 13. During the process of growing silicon carbide crystals (4H-SiC) using the TSSG method described above, since the carbon source and silicon source 14 are placed in the graphite crucible 12, the graphite crucible 12 can provide silicon carbide crystals (4H-SiC) ) The carbon source required for growth makes the carbon source continue to be supplied during the growth of silicon carbide crystal (4H-SiC), but the silicon source required for the growth of silicon carbide crystal (4H-SiC) is very limited. Crystal (4H-SiC) growth The lack of silicon source will affect the crystal growth.

In view of the problems existing in the above equipment, an improved device is shown in FIG. 2. The device shown in FIG. 2 adds a carbon source and a silicon source supplement container 18 on the basis of the device in FIG. 1. The carbon source A supplemental carbon source and a silicon source 19 are placed in the silicon source replenishment container 18. During the growth of silicon carbide crystal (4H-SiC), the carbon source and silicon source replenishment container 18 continues to add the carbon crucible 12 to the graphite crucible 12 The supplementary carbon source and silicon source 19 are described to ensure the carbon source and silicon source required for the growth of the silicon carbide crystal (4H-SiC). However, after the carbon source and the silicon source supplement container 18 for providing the supplemental carbon source and the silicon source 19 are added to the equipment as shown in FIG. 2, during the process of growing silicon carbide crystal (4H-SiC), the supplemental carbon The continuous addition of the source and the silicon source 19 will cause the temperature of the molten carbon source and the silicon source 14 in the graphite crucible 12 to decrease, thereby causing defects in the grown silicon carbide crystal (4H-SiC).

In view of the problems existing in the equipment shown in FIG. 1, another improvement solution is to replace the graphite crucible 12 in FIG. 1 with a silicon carbide crucible, but the silicon carbide crucible has the problems of insufficient purity and high cost.

The purpose of the present invention is to overcome the defects in the prior art, to provide a crucible, a method for preparing the crucible, and a method for growing silicon carbide crystals (4H-SiC), which are used to solve the crucibles in the prior art that cannot continuously replenish silicon carbide crystals (4H-SiC). The problem of silicon source required for SiC) growth. During the growth of silicon carbide crystal (4H-SiC), the carbon source and silicon source solution required for crystal growth caused by the continuous addition of carbon source and silicon source to the graphite crucible were reduced. As a result, the problem of defects in the grown silicon carbide crystal (4H-SiC) memory and the problems of insufficient purity and high cost of using the silicon carbide crucible are caused.

In order to achieve the above object and other related objectives, the present invention provides a crucible, the crucible includes: a graphite crucible body; and a silicon carbide layer located on an inner wall of the graphite crucible body.

As a preferred solution of the crucible of the present invention, the silicon carbide layer is a polycrystalline silicon carbide layer.

As a preferred solution of the crucible of the present invention, the silicon carbide layer completely covers the inner wall of the graphite crucible body.

As a preferred solution of the crucible of the present invention, the thickness of the silicon carbide layer is less than 15 cm.

The invention also provides a method for preparing a crucible. The method includes the following steps: (1) providing a graphite crucible body; and (2) forming a silicon carbide layer on an inner wall of the graphite crucible body.

As a preferred solution of the method for preparing the crucible of the present invention, the silicon carbide layer formed in step (2) is a polycrystalline silicon carbide layer.

As a preferred solution of the method for preparing a crucible of the present invention, in the step (2), the SiC layer is formed on the inner wall of the graphite crucible body by a CVD process.

As a preferred solution of the method for preparing the crucible of the present invention, forming the silicon carbide layer on the inner wall of the graphite crucible body by a CVD process includes the following steps: (2-1) placing the graphite crucible body on a CVD A reaction chamber; (2-2) passing a reaction gas into the CVD reaction chamber to perform a reaction, so as to form the silicon carbide layer on an inner wall of the graphite crucible body;

As a preferred solution of the method for preparing the crucible of the present invention, in step (2-2), the reaction gas includes: SiHCl ₃ , C ₃ H _8, and H ₂ .

As a preferred solution of the method for preparing the crucible of the present invention, the inlet flow rate of the SiHCl ₃ is 500 sccm to 3000 sccm; the inlet flow rate of the C ₃ H ₈ is 500 sccm to 3000 sccm; and the reaction temperature is 1000 ° C to 1300 ° C; The reaction pressure is from 500 Torr to 760 Torr.

As a preferred solution of the method for preparing a crucible of the present invention, the thickness of the silicon carbide layer formed on the inner wall of the graphite crucible body in step (2) is less than 20 cm.

As a preferred solution of the method for preparing a crucible of the present invention, after step (2), a step of subjecting the structure obtained in step (2) to a high-temperature treatment is further included.

As a preferred solution of the method for preparing the crucible of the present invention, the structure obtained in step (2) is placed in an oxygen environment for high temperature treatment, and the temperature for the high temperature treatment is 500 ° C to 1000 ° C.

As a preferred solution of the method for preparing the crucible of the present invention, after the structure obtained in step (2) is subjected to high-temperature processing, the thickness of the silicon carbide layer remaining on the inner wall of the graphite crucible body is less than 15 cm.

The invention also provides a method for growing silicon carbide crystal (4H-SiC). The method for growing silicon carbide crystal (4H-SiC) includes the following steps: (1) preparing a crucible, the crucible comprising a graphite crucible body and The silicon carbide layer on the inner wall of the graphite crucible body is described; (2) A carbon source and a silicon source are placed in the crucible, and the silicon carbide crystal (4H-SiC) is grown by a top seed crystal pulling method.

As a preferred scheme of the method for growing silicon carbide crystals (4H-SiC) of the present invention, the crucible is prepared by using the method for preparing a crucible described in any one of the above schemes.

The crucible, the method for preparing the crucible, and the method for growing silicon carbide crystal (4H-SiC) have the following beneficial effects: The crucible of the present invention forms a silicon carbide layer on the inner wall of the graphite crucible body, and the silicon carbide layer can be The silicon carbide crystal (4H-SiC) is used as a supplemental carbon source and silicon source during the growth process; the crucible does not have the problem of insufficient purity, and the cost of the crucible is greatly reduced compared to the cost of the silicon carbide crucible.

10‧‧‧ Crystal Growth Furnace

11‧‧‧ support

12‧‧‧graphite crucible

13‧‧‧seed

14‧‧‧ Carbon source and silicon source

15‧‧‧ base

16‧‧‧ Insulation

17‧‧‧ heater

18‧‧‧ Carbon source and silicon source supplement container

19‧‧‧Supplement of carbon and silicon sources

20‧‧‧ Crucible

201‧‧‧graphite crucible body

202‧‧‧Silicon Carbide Layer

21‧‧‧CVD reaction chamber

22‧‧‧ Gas Pipe

23‧‧‧Support

24‧‧‧Exhaust pipe

FIG. 1 and FIG. 2 are schematic structural diagrams of crucibles provided in the prior art.

FIG. 3 is a schematic structural diagram of a crucible provided in Embodiment 1 of the present invention.

FIG. 4 is a flowchart of a method for preparing a crucible provided in Embodiment 2 of the present invention.

FIG. 5 is a schematic structural diagram of a crucible prepared by a CVD process in a method for preparing a crucible provided in Embodiment 2 of the present invention.

FIG. 6 is a flowchart of a method for preparing a crucible provided in Embodiment 3 of the present invention.

The following describes the embodiments of the present invention through specific specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through different specific implementations, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

Please refer to Figures 3 to 5. It should be noted that the illustrations provided in this embodiment only illustrate the basic idea of the present invention in a schematic manner, although the illustrations only show the components related to the present invention and not the number, shape and For size drawing, the type, quantity, and proportion of each component can be changed at will in actual implementation, and the layout of the components may be more complicated.

Embodiment one:

Referring to FIG. 3, the present invention provides a crucible 20 including a graphite crucible body 201 and a silicon carbide layer 202. The silicon carbide layer 202 is located on an inner wall of the graphite crucible body 201. The crucible 20 of the present invention is formed by forming the silicon carbide layer 202 on the inner wall of the graphite crucible body 201, and the silicon carbide layer 202 can be used as a supplemental carbon source during the growth of silicon carbide crystal (4H-SiC) and Silicon source to ensure sufficient supply of carbon source and silicon source during the growth of silicon carbide crystal (4H-SiC); the crucible 20 of the present invention does not have the problem of insufficient purity, and the cost of the crucible 20 is compared to The cost of a silicon carbide crucible is greatly reduced.

As an example, the silicon carbide layer 202 is a polycrystalline silicon carbide layer.

As an example, the silicon carbide layer 202 completely covers the inner wall of the graphite crucible body 201. Of course, in other examples, the silicon carbide layer 202 may also cover part of the inner wall of the graphite crucible body 201.

As an example, the thickness of the silicon carbide layer 202 can be set according to actual needs, taking into account factors such as the expected purpose and cost of the silicon carbide layer 202 to achieve, preferably, in this embodiment, the silicon carbide layer 202 The thickness is less than 15cm.

Embodiment two:

Referring to FIG. 4, the present invention also provides a method for preparing a crucible. The method for preparing a crucible is suitable for preparing the crucible described in Example 1. The method for preparing the crucible includes the following steps: (1) providing a graphite crucible body (2) A silicon carbide layer is formed on the inner wall of the graphite crucible body.

In step (1), refer to step S1 in FIG. 4 to provide a graphite crucible body.

In step (2), referring to step S2 in FIG. 4, a silicon carbide layer is formed on the inner wall of the graphite crucible body.

As an example, the formed silicon carbide layer may be, but is not limited to, a polycrystalline silicon carbide layer.

As an example, physical vapor deposition (PVD) or chemical vapor deposition (CVD) can be used to form the silicon carbide layer on the inner wall of the graphite crucible body. Preferably, in this embodiment, a CVD process is used. The silicon carbide layer is formed on an inner wall of the graphite crucible body.

As an example, the structure diagram of a device for forming the silicon carbide layer on the inner wall of the graphite crucible body using a CVD process is shown in FIG. 5. The CVD process forms the The silicon carbide layer includes the following steps: (2-1) placing the graphite crucible body 201 in a CVD reaction chamber 21 in a CVD apparatus, and a support frame 23 is provided in the CVD reaction chamber 21, and the graphite crucible body 201 is located on the top of the support frame 23; an exhaust pipe 24 is provided at the bottom of the CVD reaction chamber 21; a heater 25 is provided around the CVD reaction chamber 21; (2-2) the reaction gas is passed through the exhaust The hole 24 opens into the CVD reaction chamber 21 for reaction, so as to form the silicon carbide layer 202 on the inner wall of the graphite crucible body 201.

As an example, the reaction gas may include SiHCl ₃ , C ₃ H _8, and H ₂ .

As an example, the inlet flow rate of the SiHCl ₃ is 500 sccm to 3000 sccm; the inlet flow rate of the C ₃ H ₈ is 500 sccm to 3000 sccm; the reaction temperature for forming the silicon carbide layer is 1000 ° C. to 1300 ° C .; The reaction pressure of the silicon layer is 500Torr ~ 760Torr.

As an example, the thickness of the silicon carbide layer formed on the inner wall of the graphite crucible body is less than 20 cm.

As an example, the step (2) further includes a step of subjecting the structure obtained in the step (2) to a high-temperature treatment.

Specifically, the structure obtained in step (2) is placed in an oxygen environment for high-temperature treatment, and the temperature of the high-temperature treatment is 500 ° C to 1000 ° C.

As an example, during the high-temperature treatment of the structure obtained in step (2), some silicon carbide reacts with oxygen and is consumed. Preferably, in this embodiment, after the high-temperature treatment is performed on the structure obtained in step (2), The thickness of the silicon carbide layer remaining on the inner wall of the graphite crucible body is less than 15 cm.

Embodiment three:

Referring to FIG. 6, the present invention also provides a method for growing silicon carbide crystal (4H-SiC). The method for growing silicon carbide crystal (4H-SiC) includes the following steps: (S6-1) preparing a crucible, where The crucible includes a graphite crucible body and a silicon carbide layer on an inner wall of the graphite crucible body; (S6-2) placing a carbon source and a silicon source in the crucible, and growing the seed crystal by a top seed crystal (TSSG) method; Silicon carbide crystal (4H-SiC).

As a preferred solution of the method for growing silicon carbide crystals (4H-SiC) according to the present invention, in step 1), the crucible preparation method described in Example 2 is used to prepare the crucible. For a specific method for preparing the crucible, please refer to Example 2, which is no longer similar here.

In summary, the present invention provides a crucible, a method for preparing the crucible, and a method for growing silicon carbide crystal (4H-SiC). The crucible includes: a graphite crucible body; and a silicon carbide layer on an inner wall of the graphite crucible body. on. The crucible of the present invention forms a silicon carbide layer on the inner wall of the graphite crucible body. The silicon carbide layer can be used as a supplemental carbon source and a silicon source during the growth of silicon carbide crystal (4H-SiC); the crucible does not have insufficient purity. The problem is high, and the cost of the crucible is greatly reduced compared to the cost of the silicon carbide crucible.

The above-mentioned embodiments merely illustrate the principle of the present invention and its effects, but are not intended to limit the present invention. Anyone familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field to which they belong without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the scope of patent application of the present invention.

Claims (16)

    A crucible includes: a graphite crucible body; and a silicon carbide layer on an inner wall of the graphite crucible body.         The crucible according to claim 1, wherein the silicon carbide layer is a polycrystalline silicon carbide layer.         The crucible according to claim 1, wherein the silicon carbide layer completely covers an inner wall of the graphite crucible body.         The crucible of claim 1, wherein the thickness of the silicon carbide layer is less than 15 cm.         A method for preparing a crucible includes the following steps: (1): providing a graphite crucible body; (2): forming a silicon carbide layer on an inner wall of the graphite crucible body.         The method for preparing a crucible according to claim 5, wherein the silicon carbide layer formed in the step (2) is a polycrystalline silicon carbide layer.         The method for preparing a crucible according to claim 5, wherein in the step (2), the silicon carbide layer is formed on an inner wall of the graphite crucible body by a chemical vapor deposition process.         The method for preparing a crucible according to claim 7, wherein forming the silicon carbide layer on the inner wall of the graphite crucible body by a chemical vapor deposition process includes the following steps: (2-1) the graphite crucible body Placed in a chemical vapor deposition reaction chamber; (2-2) passing a reaction gas into the chemical vapor deposition reaction chamber to perform a reaction to form the silicon carbide layer on the inner wall of the graphite crucible body.     The method for preparing a crucible according to claim 8, wherein in the step (2-2), the reaction gas includes: SiHCl ₃ , C ₃ H _8, and H ₂ . The method for preparing a crucible according to claim 9, wherein the inlet flow rate of the SiHCl ₃ is 500 sccm (standard cubic centimeter per minute) to 3000 sccm; the inlet flow rate of the C ₃ H ₈ is 500 sccm to 3000 sccm; and the reaction temperature is 1000 ° C ~ 1300 ° C; the reaction pressure is 500Torr ~ 760Torr.     The method for preparing a crucible according to claim 5, wherein the thickness of the silicon carbide layer formed on the inner wall of the graphite crucible body in the step (2) is less than 20 cm.         The method for preparing a crucible according to any one of claims 5 to 11, wherein the step (2) further includes a step of subjecting the structure obtained in the step (2) to a high-temperature treatment.         The method for preparing a crucible according to claim 12, wherein the structure obtained in the step (2) is subjected to a high temperature treatment under an oxygen environment, and the temperature of the high temperature treatment is 500 ° C to 1000 ° C.         The method for preparing a crucible according to claim 13, wherein after the structure obtained in the step (2) is subjected to high temperature treatment, the thickness of the silicon carbide layer remaining on the inner wall of the graphite crucible body is less than 15 cm.         A method for growing silicon carbide crystal (4H-SiC) includes the following steps: preparing a crucible, the crucible comprising a graphite crucible body and a silicon carbide layer on an inner wall of the graphite crucible body; and placing a carbon source and a silicon source In the crucible, a silicon carbide crystal (4H-SiC) is grown by a top seed crystal pulling method.         The method for growing a silicon carbide crystal (4H-SiC) according to claim 15, wherein the crucible is prepared using the method for preparing a crucible according to any one of claims 5 to 14.