WO2017113368A1

WO2017113368A1 - Crucible for growth of silicon carbide crystal

Info

Publication number: WO2017113368A1
Application number: PCT/CN2015/100284
Authority: WO
Inventors: 孔海宽; 忻隽; 陈建军; 郑燕青; 施尔畏
Original assignee: 中国科学院上海硅酸盐研究所
Priority date: 2015-12-29
Filing date: 2015-12-31
Publication date: 2017-07-06
Also published as: CN106929919A

Abstract

The present invention relates to a crucible for the growth of a silicon carbide crystal, comprising a raw material cavity (2) for holding the raw materials for the growth of the SiC crystal; a growth cavity (1) nested within the upper part of the raw material cavity (2) with relative movement to form a crystalline region of a crystal, wherein the growth cavity (1) has a growth chamber (4) and a seed pad (3) arranged on the top wall of the growth chamber (4). The crucible of the present invention can adjust the distance between the surface of the crystal and the surface of the raw materials during growth, and can maintain the stability of the temperature field, thereby being a crucible for the growth of a silicon carbide crystal for growing high quality silicon carbide crystals.

Description

Specification Name of Invention: A Kind of Silicon Carbide Crystal Growth 坩埚 Technical Field

[0001] The present invention relates to the field of crystal growth, and relates to a ruthenium structure for growing SiC crystal by physical vapor transport, and more particularly to a ruthenium for crystal growth of silicon carbide.

Background technique

[0002] SiC crystals have large forbidden band width, strong critical breakdown field, high saturation drift velocity, and low thermal expansion coefficient

, a series of advantages such as strong radiation resistance, is a new generation of semiconductor materials that are attracting attention, in microwave radio frequency

Applications such as power devices and LED substrates have broad application prospects. Especially in the past ten years, both SiC crystal materials and related device applications have made great progress, and SiC crystal devices have gradually entered the industries of power electronics, new energy vehicles, and LED lighting.

[0003] The SiC crystal growth generally adopts physical vapor transport (PVT), and its basic principle is shown in Fig. 4. The SiC crystal is grown by an induction heating furnace, and the crystal is grown in the graphite crucible 105. Usually, the SiC raw material 104 is placed in the lower portion of the growth chamber of the crucible 105, and the seed crystal 103 is fixed on the seed crystal holder 102 on the top of the growth chamber, and the graphite crucible 105 is wrapped around the periphery. An insulating material is used as the insulating layer 106, and a temperature measuring hole 101 is formed on the top of the insulating layer 106. The temperature field of the crystal growth is constructed by adjusting the position of the crucible 105 in the induction coil and the structure of the insulative material, and the temperature and pressure conditions of the growth chamber are precisely controlled during the growth process, so that the SiC raw material 104 is sublimated from the lower portion of the crucible 105, and rises to The seed crystal 103 is subjected to stack growth to finally obtain a SiC single crystal.

4 shows the structure of a crucible 105 used in the growth of a conventional SiC crystal in which the position of the seed crystal 103 and the SiC raw material 104 is relatively fixed in the closed graphite crucible 105. For example, in the related patents 200680013 157.1, 200580032490.2, 201320740468.5, etc., although the internal structure of the crucible differs from that of the seed crystal structure, it is a closed and fixed structural design.

[0005] However, a large number of experiments have found that in the early stage of crystal growth, due to the inevitable process of temperature rise and depressurization process control, there is a certain temperature gradient instability and insufficient transport of gas phase components inside the crucible, resulting in sublimation destruction of the seed crystal. A large number of defects are introduced in crystal growth. In addition, as the crystal growth process progresses, the crystal gradually thickens, and the distance between the crystal surface and the surface of the raw material decreases, which also leads to the internal temperature ladder of the crucible. Degree changes often lead to polymorphic derivation and other crystal defects.

[0006] Therefore, designing a new ruthenium structure, combined with the corresponding crystal growth process control technology, can adjust the position of the seed crystal, avoid seed sublimation damage during the crystal inoculation growth stage, and can adjust the crystal surface and raw materials during the growth process. The distance of the surface, maintaining the stability of the temperature field, is important for growing high quality SiC crystals.

technical problem

In view of the above problems, the technical problem to be solved by the present invention is to provide a method capable of adjusting the distance between the surface of the crystal and the surface of the raw material during the growth process, maintaining the stability of the temperature field, thereby growing high quality silicon carbide crystals. The silicon carbide crystal is grown by ruthenium.

Problem solution

Technical solution

[0008] In order to solve the above problems, the silicon carbide crystal growth enthalpy provided by the present invention comprises: a raw material cavity for holding a raw material for SiC crystal growth; and a relatively movable nested in an upper portion of the raw material cavity A growth chamber forming a crystalline crystal region, the growth chamber having a growth chamber and a seed holder disposed on a top wall of the growth chamber.

[0009] According to the present invention, the silicon carbide crystal growth is divided into two parts, the upper part is a growth cavity, including a seed crystal holder and a growth chamber, which are crystal crystal regions; and the lower part is a raw material cavity for holding raw materials for SiC crystal growth. . The growth chamber and the raw material chamber are combined to form a crystal growth crucible, and the relative positions of the growth chamber and the raw material chamber can be adjusted, thereby adjusting the position of the seed crystal in the early stage of crystal growth, thereby preventing the seed crystal from being destroyed under unstable temperature gradient conditions; The process can adjust the distance between the crystal growth surface and the raw material, maintain stable crystal growth conditions and growth process, and grow high quality silicon carbide crystals.

Further, in the invention, the material chamber may include a guide cylinder located at an upper portion and a material storage portion located at a lower portion, and the growth chamber may be nested in the guide cylinder.

[0011] According to the present invention, the guiding cylinder is mainly used for assembling with the growth chamber to exert a motion guiding effect, and the same is also used for constructing the temperature field in the growth chamber, and also as an external heating body of the growth chamber. The growth chamber is nested within the guide barrel at the upper portion of the material chamber, and the two are relatively free to slide and rotate.

1毫米。 The gap is 0. lmm - 3mm. The gap between the outer surface of the side wall of the growth chamber and the inner surface of the guide tube is 0. lmm - 3mm. [0013] According to the present invention, it is advantageous to achieve relative free sliding and rotation of both the growth chamber and the guide barrel.

Further, in the invention, the material chamber may further include an annular flow guide located between the guide cylinder and the raw material accommodating portion.

[0015] According to the present invention, by providing a baffle, the gas phase component of the raw material sublimated in the feed zone can be transported to the central region of the growth chamber to achieve continuous crystal growth, avoiding the gap between the gas phase component and the growth chamber and the guide cylinder. Escapes 坩埚, affecting crystal growth.

Further, in the invention, the lower portion of the baffle may be formed in a slope structure.

[0017] According to the present invention, it may be further advantageous to direct the sublimated raw material gas phase component to be transported to the central region of the growth chamber.

Further, in the invention, the side wall of the growth chamber may be formed as a solid structure, a hollow structure, or an expanded diameter structure.

[0019] According to the present invention, the sidewall of the growth chamber can be formed as a solid structure, a hollow structure, or an expanded diameter structure to meet the needs of temperature gradient adjustment, crystal shape control, and the like.

Further, in the invention, the top of the growth chamber may be provided with a connection portion connected to the upper pulling mechanism of the growth furnace.

[0021] According to the present invention, by providing a connection portion connected to the upper pulling mechanism of the growth furnace at the top of the growth chamber, the lifting movement and the rotation control of the growth chamber can be realized by the pulling action of the upper pulling mechanism.

Further, in the present invention, the material chamber may be placed on a bottom stage of the growth furnace, and the material chamber may be raised and lowered with the bottom tray.

[0023] According to the present invention, the lifting and turning control of the material chamber can be achieved during the crystal growth process.

Further, in the invention, the material of the crucible may be graphite, tantalum, niobium, niobium carbide, or tantalum carbide.

[0025] According to the present invention, the use of a high temperature resistant material such as graphite, tantalum, niobium, tantalum carbide, or niobium carbide to produce niobium can improve the high temperature resistance of niobium.

Further, in the invention, the material of the crucible may be a graphite material crucible, and the surface of the crucible may be coated with a ruthenium, rhodium, tungsten, tantalum carbide or tantalum carbide coating.

[0027] According to the present invention, the crucible is made of a graphite material, and various anti-high temperature coatings such as tantalum, niobium, tungsten, tantalum carbide, or tantalum carbide are coated on the surface of the crucible to suppress or prevent the graphite crucible in the crystal. Growing process Destruction occurs to ensure that the crystal growth process is stable.

The above and other objects, features and advantages of the present invention will become <RTIgt;

Advantageous effects of the invention

Brief description of the drawing

DRAWINGS

1 is a schematic view showing the structure of a crucible for SiC crystal growth according to an embodiment of the present invention;

2 is a schematic view showing the structure of a growth system for crystal growth using the crucible shown in FIG. 1;

3 is a schematic structural view of a SiC crystal growth crucible according to another embodiment of the present invention; [0032] FIG. 4 is a schematic view showing a structure of a growth system in which a SiC crystal is grown by a PVT method in the prior art;

[0033] Reference numerals: 1, growth chamber, 2, raw material chamber, 3, seed crystal holder, 4, growth chamber, 5, 51, growth chamber side cylinder, 6, guiding cylinder, 7, guide, 8, Raw material, 9, connection part, 10, growth furnace body, 11, upper lifting rod, 12, bottom support, 13, upper lifting parts, 14, lifting parts, 15, lifting rod, 16, insulation material, 17, coil 101, temperature measuring hole, 102, seed crystal 103, seed crystal, 104, SiC raw material, 105, 坩埚, 106, insulating layer.

Embodiments of the invention

The present invention is further described in the following description of the embodiments of the invention, and the accompanying drawings

[0035] In view of the fact that the ruthenium structure of the seed crystal and the raw material which are usually used in the current growth of SiC crystals is relatively fixed, in order to avoid the damage of the seed crystal due to temperature field instability in the early stage of crystal growth, and the distance between the seed crystal and the raw material during the growth process cannot be Disadvantages of the adjustment, the present invention designs a novel ruthenium structure for growing SiC crystals. The combined mechanical mechanism of the growth furnace enables independent motion control of the seed crystal (and the growing crystal) and the raw material. To this end, the present invention provides a crucible for crystal growth of silicon carbide, comprising: a raw material chamber for containing a raw material for growing SiC crystal; and a relatively movable inside nested in an upper portion of the raw material chamber to form a crystal crystalline region; a growth chamber having a growth chamber and a seed holder disposed on a top wall of the growth chamber. [0036] Specifically, the SiC crystal growth crucible is mainly composed of upper and lower portions, and the upper portion is called a growth chamber, and the main components include a seed crystal holder and a growth chamber, and the growth chamber is a crystal crystallization region. The lower part of the crucible is a raw material chamber for holding raw materials for SiC crystal growth.

[0037] Moreover, the upper and lower parts of the crucible, that is, the growth chamber and the raw material chamber, are used in combination for crystal growth, wherein the growth chamber can be relatively moved and nested in the upper region of the raw material chamber. The material chamber may have a guide cylinder at the upper portion and a material accommodating portion at the lower portion, and the growth chamber may be nested in the guide cylinder so as to be relatively movable. That is, after the growth chamber is combined with the material chamber, the growth chamber can be moved up and down in the direction of the guide cylinder.

[0038] Preferably, a small gap is maintained between the outer wall of the growth chamber and the inner wall of the raw material chamber (the guide cylinder), that is, the outer surface of the side wall of the growth chamber and the inner surface of the guide cylinder to ensure that the two are opposite Free sliding and rotating, the general clearance is 0.1mm - 3mm.

[0039] In addition, an inner annular wall region of the raw material chamber located between the guiding cylinder and the raw material receiving portion may be provided with an annular guide table

The lower portion of the deflector may be formed as a slope structure to guide the gas phase component sublimated in the feed zone to the central region of the growth chamber.

[0040] Further, the cylindrical growth chamber side wall (i.e., the growth chamber side tube) can be designed into a solid or hollow structure and other shapes according to the crystal growth temperature field requirement, to meet the needs of temperature gradient adjustment, crystal shape control, and the like.

[0041] In addition, a connection portion connected to a lifting mechanism of the growth furnace, such as an upper lifting rod, may be provided at the top of the growth chamber of the crucible, so that the growth chamber can be realized by the upper pulling mechanism of the growth furnace. Lifting movement and turning function.

[0042] Generally, the raw material cavity can be placed on the bottom support of the growth furnace. Preferably, for the growth furnace having the lifting and rotating functions of the bottom support, the lifting and rotation control of the raw material cavity can also be realized during the crystal growth process. .

[0043] The material of the crucible of the present invention is generally a graphite material, and a high temperature resistant material such as tantalum, niobium, tantalum carbide or niobium carbide can also be used. When graphite is used to process the above structure, various high temperature resistant coatings such as tantalum, niobium, tungsten, tantalum carbide, niobium carbide and the like may be applied to the surface of the graphite crucible.

[0044] The crucible of the invention is combined with the corresponding growth process, and on the one hand, in the early stage of heating growth, the growth chamber can be placed at a higher position, the seed crystal is kept away from the high temperature region, and the sublimation destruction of the seed crystal in the depressurization phase is avoided. Warming to a suitable temperature, reducing the pressure to the pressure required for growth, reducing the seed crystal to a suitable position, and starting crystal growth; On the other hand, in the crystal growth stage, the growth chamber position is continuously increased slowly, so that the crystal growth surface and the raw material maintain a stable distance to achieve the purpose and effect of making the crystal growth more stable.

[0045] Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

1 shows a crucible for SiC crystal growth according to an embodiment of the present invention. As shown in FIG. 1, the crucible of this embodiment can be roughly divided into upper and lower parts, and the upper part is a growth chamber 1, which includes a seed crystal holder 3, a growth chamber 4, and a growth chamber side cylinder 5, which is a gas phase transport and Crystal crystalline region. The lower portion of the crucible is a raw material chamber 2, and is mainly used for holding a raw material for SiC crystal growth, and a guide cylinder 6 is provided at the upper end of the raw material chamber 2.

[0047] The growth chamber 1 and the raw material chamber 2 are combined to form a crucible for growing the SiC crystal. As shown in FIG. 1, the growth chamber 1 is nested in the upper portion of the raw material chamber, and has a small gap therebetween. And the outer wall of the growth chamber 1 and the inner wall of the guide cylinder 6 are appropriately treated to make the surface smooth, so as to ensure that the two can slide and rotate relatively freely, and the gap is generally 0.1 mm - 3 mm.

2 is a schematic view showing the structure of a growth system for crystal growth using the crucible shown in FIG. 1. As shown in Fig. 2, the crucible is placed on the bottom tray 12 in the growth furnace body 10, and is surrounded by the heat insulating material 16, and is surrounded by an induction coil 17, through which the crucible 17 is heated. As shown in FIG. 1 and FIG. 2, in order to control the movement and rotation of the growth chamber 1, the top of the growth chamber 1 is provided with a corresponding mechanical component of the growth furnace, for example, a connection portion 9 connected to the upper pull rod 11, and is pulled up. The component 13 drives the connecting portion 9 to move via the upper pull rod 11. As also shown in Fig. 1, the growth chamber side cylinder 5 can be formed into a solid structure.

[0049] The upper part of the material chamber 2 is a guiding cylinder 6, which is mainly used for assembling with the growth chamber 1 to exert a motion guiding effect, and is also used for constructing a temperature field in the growth chamber 4, and can also be used as an external heating body of the growth chamber. . The height and inner diameter and outer diameter of the guiding cylinder 6 are closely combined with the size of the growth chamber 1, and the temperature gradient condition needs to be designed, and the height may be greater than or less than or equal to the height of the growth chamber 1, which is related to the internal temperature field construction of the crucible. It is also related to the crystal growth process conditions and is affected by many factors and can generally be determined experimentally.

[0050] As shown in FIG. 1, the inner wall region of the raw material chamber 2, that is, the lower end of the guiding cylinder 6, has an annular flow guiding platform 7, and the lower portion of the guiding platform 7 has a slope structure for guiding the gas phase component of the raw material 8 sublimation to the growth chamber. The central region of 4 transports, achieving continuous crystal growth, avoiding gas phase components from escaping along the gap between the growth chamber 1 and the guide cylinder 6, affecting crystal growth. Further, the flow guide 7 is generally formed into a triangular structure as shown in Fig. 1, and may be designed in other shapes for the purpose of guiding the transport direction of the gas phase components.

[0051] As shown in FIG. 2, the material chamber 2 is placed on the bottom tray 12 of the growth furnace, and has a lifting and rotating rotation for the bottom tray. In the case of a functional growth furnace, the lifting and rotation control of the crucible material chamber 2 can also be achieved during the crystal growth process, depending on the crystal growth process requirements. For example, as shown in FIG. 2, the bottom pallet 12 is connected to the elevating member 14 via the elevating rod 15, and is moved by the elevating member 14.

The crucible material of the present embodiment is generally a graphite material, and a high temperature resistant material such as tantalum, niobium carbide or tantalum carbide may be used.

[0053] Further, when the crucible is processed by a graphite material, various high temperature resistant coatings may be applied on the surface or part of the surface of the graphite crucible, such as germanium, antimony, tungsten, and materials such as tantalum carbide and tantalum carbide. It is used to inhibit or avoid the destruction of graphite crucible during crystal growth, and to ensure the crystal growth process is stable.

3 shows a crucible for SiC crystal growth according to another embodiment of the present invention. As shown in Fig. 3, in the present embodiment, the growth chamber side cylinder 51 is formed in a hollow structure, and the SiC crystal growth crucible shown in Fig. 3 is basically the same as the embodiment of Fig. 1, and the same components are the same. The reference numerals are shown, and the description will not be repeated here.

[0055] However, the structure of the growth chamber side cylinder of the present invention is not limited thereto, and the temperature field conditions required for crystal growth are considered, and the diameter expansion structure and other shapes may be designed to satisfy temperature gradient adjustment, crystal shape control, and the like. need.

[0056] Hereinafter, the SiC crystal growth crucible of the present invention will be further described in detail by way of specific examples.

Embodiment 1

[0058] The SiC crystal growth crucible having the structure shown in FIG. 1 was prepared by using a high-purity graphite material (purity >99.9%), and the gap between the outer wall of the growth chamber 1 and the inner wall of the guide cylinder 6 was 0.5 mm. The specific structure is as described above. By adopting the structure, the growth chamber 1 can be controlled to rise and fall during the crystal growth process, the seed crystal position is controlled during the early crystal growth stage, and the distance between the crystal growth surface and the raw material is adjusted during the growth process to grow high quality SiC crystal.

Example 2

[0060] The SiC crystal growth crucible having the structure shown in FIG. 3 is prepared by using a high-purity graphite material (purity >99.9%), wherein the growth chamber 1 includes a seed crystal holder 3, a growth chamber 4, and a growth chamber side cylinder having a cavity. 5. The material chamber 2 includes a guiding cylinder 6, a baffle 7, and a material 8 can be contained therein.

[0061] In this embodiment, the growth chamber side cylinder is formed into a cavity structure, and to achieve this design, the growth chamber 1 is assembled by a plurality of different components. [0062] The growth chamber 1 is combined with the raw material chamber 2, and the growth chamber 1 is nested in the guide cylinder 6, and the gap between the two is 0.1 mm. The outer wall of the growth chamber 1 and the inner wall surface of the guide cylinder 6 are smooth, and the two can slide relatively freely. And turning.

[0063] The top of the growth chamber 1 is provided with a connection to the corresponding mechanical component of the growth furnace.

The growth chamber side barrel 5 is formed in a hollow structure to improve the temperature gradient in the growth chamber 4, particularly the radial temperature gradient. Under the electromagnetic induction, the outer surface of the sidewall of the graphite crucible is the main part of the heat generation. The heat is conducted or radiated from the sidewall of the crucible to the center of the growth chamber. When the side cylinder of the growth chamber is a solid structure, the heat is transferred from the side cylinder by heat conduction. The outer wall is directed to the inner wall and then radiates toward the center of the growth chamber. When the side tube of the growth chamber is a hollow structure, heat is radiated from the outer wall of the side tube to the inner wall. Experiments have shown that the hollow structure slows down the heat transfer rate and is conducive to constructing growth. Smaller radial temperature gradients in the room.

[0065] The guiding cylinder 6 of the raw material chamber 2 has the same height as the growth chamber 1, that is, the growth chamber 1 is placed on the baffle 7, and the top surface of the growth chamber 1 is level with the top surface of the guiding cylinder 6. The lower portion of the deflector 7 has a slope structure.

[0066] In the present embodiment, the cavity structure design of the growth chamber side cylinder 5 is mainly used to adjust the radial temperature gradient in the growth chamber, combined with the design of the relevant insulation system and the growth process parameter control, which is beneficial to further optimize the crystal growth process control. , growing high quality SiC crystals.

Example 3

[0068] The ruthenium for SiC crystal growth of the structure shown in FIG. 1 was prepared by using ruthenium (metal element) (purity >99.9%), and the specific structure was as described above. The gap between the outer wall of the growth chamber 1 and the inner wall of the guide cylinder 6 is lmm. The use of bismuth prevents the C element in the graphite crucible from becoming a part of the C source for the growth of the SiC crystal, and is more conducive to the control of the gas phase component. The same enthalpy can also control the rise and fall of the growth chamber 1 during the crystal growth process. The seeding position is controlled during the inoculation stage, and the distance between the crystal growth surface and the raw material is adjusted during the growth process, and finally a high quality SiC crystal is grown.

[0069] The present invention may be embodied in a variety of forms without departing from the spirit and scope of the invention. All changes which come within the scope of the claims, and the scope of the claims

Claims

Claim

A crucible for crystal growth of silicon carbide, characterized in that it comprises:

a raw material cavity for holding raw materials for SiC crystal growth;

a growth chamber that is relatively movably nested within the upper portion of the material chamber to form a crystalline crystalline region, the growth chamber having a growth chamber and a seed holder disposed on a top wall of the growth chamber. The silicon carbide crystal growth crucible according to claim 1, wherein the raw material chamber has a guide cylinder located at an upper portion and a raw material storage portion at a lower portion, and the growth chamber is fitted in the guide cylinder.

The crucible for crystal growth of silicon carbide according to claim 2, wherein a gap exists between an outer surface of the side wall of the growth chamber and an inner surface of the guide cylinder, and the gap is 0.1 mm - 3 mm.

The silicon carbide crystal growth crucible according to claim 2, wherein the raw material chamber further includes an annular flow guiding table between the guide cylinder and the raw material accommodating portion. The crucible for crystal growth of silicon carbide according to claim 4, wherein a lower portion of the baffle is formed in a sloped structure.

The crucible for crystal growth of silicon carbide according to claim 1, wherein the side wall of the growth chamber is formed into a solid structure, a hollow structure, or an expanded diameter structure.

The crucible for crystal growth of silicon carbide according to claim 1, wherein a top portion of the growth chamber is provided with a connection portion connected to an upper pulling mechanism of the growth furnace.

The crucible for crystal growth of silicon carbide according to claim 1, wherein the raw material chamber is placed on a bottom stage of the growth furnace, and the raw material chamber is lifted and rotated with the bottom stage.

The crucible for crystal growth of silicon carbide according to any one of claims 1 to 8, characterized in that the material of the crucible is graphite, ruthenium, iridium, ruthenium carbide, or tantalum carbide. The crucible for crystal growth of silicon carbide according to claim 9, wherein the crucible is made of a graphite material, and the surface of the crucible is coated with ruthenium, osmium, tungsten, tantalum carbide or tantalum carbide coating. .