Crucible device for silicon carbide single crystal growth

Abstract

The utility model discloses a crucible device for silicon carbide single crystal growth, and relates to the technical field of silicon carbide single crystal growth. The crucible device comprises a crucible in which an accommodating cavity for accommodating silicon carbide powder is formed, a seed crystal positioned at the top of the crucible and a graphite structure positioned in the accommodating cavity, and the graphite structure comprises a vertical part penetrating through the silicon carbide powder and a drainage piece positioned at the top of the vertical part; the flow guide piece is arranged to be in a shape which is surrounded by the side wall of the flow guide piece and is gradually expanded from bottom to top, the width ratio of the top surface of the flow guide piece to the seed crystal is any one value of 0.3-0.8, the diameter ratio of the vertical part to the accommodating cavity is any one value of 0.1-0.4, and the surfaces of the vertical part and the flow guide piece are coated with tantalum-containing coatings. According to the crucible device, the distribution uniformity of a temperature field in the crucible can be improved, the growth dislocation density of silicon carbide single crystals is reduced, and the growth quality of the silicon carbide single crystals is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to silicon carbide single crystal production technical field, concretely relates to a silicon carbide single crystal growth with crucible device. BACKGROUND

[0002] As the third generation semiconductor material, silicon carbide has the characteristics of large band gap, high critical breakdown field strength, high thermal conductivity, etc., and is an ideal material for manufacturing high-frequency, high-voltage, high-power and radiation-resistant devices. Physical vapor transport method is the most commonly used method for silicon carbide single crystal growth.

[0003] In the prior art, silicon carbide powder is usually placed in a crucible with an induction coil outside, and the crucible is heated to sublimate to form a silicon carbide atmosphere around the crucible, which is then transported to the surface of the seed crystal to form a silicon carbide single crystal. However, the above method usually has a large radial temperature gradient, which causes a large thermal stress in the initial growth of the silicon carbide single crystal, resulting in a high dislocation density in the silicon carbide single crystal and a problem of silicon carbide carbon wrapping, which affects the growth quality of the silicon carbide single crystal. High dislocation density will adversely affect the performance stability and long-term workability of the later device process.

[0004] Therefore, there is an urgent need for a silicon carbide single crystal growth device that can simultaneously reduce dislocation density and improve crystal growth quality. UTILITY MODEL CONTENT

[0005] One object of the utility model is to provide a silicon carbide single crystal growth crucible device to solve the problem of high dislocation density in the prior art.

[0006] Another object of the utility model is to further improve the growth quality of silicon carbide single crystal.

[0007] According to the purpose of the utility model, the utility model provides a silicon carbide single crystal growth crucible device, comprising:

[0008] A crucible having a receiving cavity for placing silicon carbide powder formed therein;

[0009] A seed crystal located at the top of the crucible;

[0010] A graphite structure located in the receiving cavity, the graphite structure comprising a vertical part passing through the silicon carbide powder and a flow guide located at the top of the vertical part, the flow guide being arranged such that its side wall forms a shape that gradually expands from the bottom upwards; wherein,

[0011] The ratio of the top surface of the flow guide to the width of the seed crystal is any value between 0.3 and 0.8, the ratio of the vertical part to the diameter of the receiving cavity is any value between 0.1 and 0.4, and the surface of the vertical part and the flow guide is coated with a tantalum-containing coating.

[0012] Optionally, the ratio of the width of the bottom surface to the width of the top surface of the flow guide is any value between 0 and 0.5.

[0013] Optionally, the top surface of the flow guide is spaced apart from the bottom surface of the seed crystal by a preset distance, and the preset distance is any value between 70 mm and 160 mm.

[0014] Optionally, the flow guide comprises a side wall formed with a special-shaped cross-section area gradually expanding upward from the bottom, and the flow guide further comprises:

[0015] a guide portion located at the top of the special-shaped cross-section area and extending in the vertical direction, and the ratio of the height of the guide portion to the height of the flow guide is any value between 0.3 and 0.5.

[0016] Optionally, the height of the guide portion is any value between 0 and 30 mm.

[0017] Optionally, the ratio of the height of the vertical portion to the height of the silicon carbide powder is any value between 1 and 1.3.

[0018] Optionally, the material of the tantalum-containing coating can be any one of tantalum or tantalum carbide.

[0019] Optionally, the material of the graphite structure is isostatic graphite.

[0020] Optionally, the width of the vertical portion is any value between 30 mm and 80 mm.

[0021] The utility model discloses a graphite structure comprising a vertical portion and a flow guide is arranged in the crucible device, and the flow guide is arranged into the ratio of the width of the top surface to the width of the seed crystal is any value between 0.3 and 0.8, the ratio of the diameter of the vertical portion to the containing cavity is any value between 0.1 and 0.4, that is to say, the vertical portion for heating the silicon carbide powder and the flow guide for guiding the silicon carbide atmosphere are arranged at the bottom of the seed crystal of the crucible device, to improve the heating uniformity of the silicon carbide powder at the middle position of the containing cavity, thereby increasing the temperature of the middle position of the seed crystal, ensuring the axial growth temperature gradient while reducing the radial temperature gradient at the seed crystal, preventing the formation of through dislocations in the silicon carbide single crystal due to the thermal stress inside the crystal in the initial stage of the growth of the silicon carbide single crystal, and guiding the silicon carbide atmosphere at the middle position at the same time, so that the silicon carbide atmosphere flows to the seed crystal through the side wall of the flow guide, reducing the formation rate of the silicon carbide single crystal at the middle position of the seed crystal, and preventing the cracking of the silicon carbide single crystal due to the excessive formation rate of the silicon carbide single crystal at the middle position of the seed crystal.

[0022] Further, the drainage member is provided with the special-shaped section area and the guide part located at the top of the special-shaped section area and extending along the vertical direction, which can not only play a role in draining the silicon carbide atmosphere, but also prevent the thermal stress from increasing due to thermal junction at the top of the drainage member, further reduce the dislocation density of the silicon carbide single crystal, and improve the growth quality of the silicon carbide single crystal.

[0023] The above description is only a summary of the technical scheme of the utility model, in order to more clearly understand the technical means of the utility model, and can be implemented according to the content of the specification, the following preferred embodiments of the utility model are described in detail below with the help of the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0024] Some specific embodiments of the utility model will be described in detail hereinafter with reference to the drawings in an exemplary but not restrictive manner. The same reference signs in the drawings indicate the same or similar components or parts. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0025] Figure 1 It is a schematic structural diagram of a crucible device according to one embodiment of the utility model;

[0026] Figure 2 It is a schematic structural diagram of a crucible device according to another embodiment of the utility model;

[0027] Figure 3 It is a temperature field distribution diagram of a crucible device in the prior art;

[0028] Figure 4 It is a schematic temperature field distribution diagram of a crucible device according to one embodiment of the utility model;

[0029] Figure 5 It is a flow field distribution diagram of a silicon carbide atmosphere in a crucible device in the prior art;

[0030] Figure 6 It is a flow field distribution diagram of a silicon carbide atmosphere in a crucible device according to one embodiment of the utility model.

[0031] Reference signs:

[0032] 100-crucible device, 10-crucible, 11-receiving cavity, 20-seed crystal, 30-graphite structure, 31-vertical part, 32-drainage member, 321-special-shaped section area, 322-guide part, 40-silicon carbide powder. DETAILED DESCRIPTION

[0033] The specific embodiments of the utility model will be further described in detail below in combination with the drawings and examples. The following examples are used to illustrate the utility model, but not to limit the scope of the utility model.

[0034] In order to make the above objects, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below with reference to the drawings. It can be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application. In addition, it should be noted that, for the sake of description, only the parts related to the present application are shown in the drawings, but not all the structures. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0035] The terms "comprising" and "having" and any variations thereof in the present application are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products or devices.

[0036] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily all refer to the same embodiment, nor does it necessarily refer to a separate or alternative embodiment. It is explicitly and implicitly understood by those skilled in the art that embodiments described herein can be combined with each other.

[0037] Figure 1 is a schematic structural diagram of a crucible device according to an embodiment of the present application, Figure 2 is a schematic structural diagram of a crucible device according to another embodiment of the present application, Figure 3 is a temperature field distribution diagram of a crucible device in the prior art, Figure 4 is a schematic temperature field distribution diagram of a crucible device according to an embodiment of the present application, Figure 5 is a flow field distribution diagram of a silicon carbide atmosphere in a crucible device in the prior art, Figure 6 is a flow field distribution diagram of a silicon carbide atmosphere in a crucible device according to an embodiment of the present application.

[0038] As Figure 1As shown, the utility model provides a kind of silicon carbide single crystal growth with crucible device 100, and the crucible device 100 includes crucible 10, seed crystal 20 and graphite structure 30, the accommodating cavity 11 for placing silicon carbide powder 40 is formed in crucible 10, seed crystal 20 is located at the top of crucible 10, graphite structure 30 is located in accommodating cavity 11, graphite structure 30 includes vertical part 31 and drainage member 32 located at the top of vertical part 31, drainage member 32 is set to its side wall encloses the shape of gradually expanding from bottom to upwards, wherein the width ratio of the top surface of drainage member 32 and seed crystal 20 is any one value in 0.3-0.8, the diameter ratio of vertical part 31 and accommodating cavity 11 is any one value in 0.1-0.4, and the surface of vertical part 31 and drainage member 32 is coated with tantalum coating.Here, vertical part 31 and drainage member 32 are connected by mechanical engagement.

[0039] In the embodiment, by setting graphite structure 30 including vertical part 31 and drainage member 32 in crucible device 100, and setting the ratio of the width of the top surface and the width of seed crystal 20 of drainage member 32 to be any one value in 0.3-0.8, the diameter ratio of vertical part 31 and accommodating cavity 11 to be any one value in 0.1-0.4, i.e. setting vertical part 31 for heating silicon carbide powder 40 and drainage member 32 for draining silicon carbide atmosphere at the bottom of seed crystal 20 of crucible device 100, the heating uniformity of silicon carbide powder 40 at the middle position of accommodating cavity 11 is improved, the temperature at the middle position of seed crystal 20 is increased, the axial growth temperature gradient is ensured, the radial temperature gradient at seed crystal 20 is reduced, the formation of through dislocation in silicon carbide single crystal due to internal thermal stress of crystal at the initial stage of silicon carbide single crystal growth is prevented, and the silicon carbide atmosphere at the middle position is drained, so that the silicon carbide atmosphere flows to seed crystal 20 through the side wall of drainage member 32, the formation rate of silicon carbide single crystal at the middle position of seed crystal 20 is reduced, and the cracking of seed crystal 20 at the middle position due to too fast formation of silicon carbide single crystal is prevented.

[0040] In the embodiment, the width ratio of vertical part 31 and accommodating cavity 11 is any one value in 0.1-0.4, i.e. the width ratio of vertical part 31 and accommodating cavity 11 can be 0.1, 0.2, 0.3 or 0.4, or any one value in 0.1-0.4. By setting the width ratio of vertical part 31 and accommodating cavity 11 in the above range, the axial temperature distribution and radial temperature distribution uniformity in crucible device 100 can be effectively adjusted, the internal thermal stress of crystal is further reduced, and the growth dislocation density of silicon carbide single crystal is reduced.

[0041] In the embodiment, the ratio of the top surface of the flow guide 32 to the width of the seed crystal 20 is any value in the range of 0.3-0.8, i.e. the ratio of the top surface of the flow guide 32 to the width of the seed crystal 20 can be 0.3, 0.4, 0.5, 0.6, 0.7 or 0.8, or any value in the range of 0.3-0.8. By setting the ratio of the top surface of the flow guide 32 to the width of the seed crystal 20 in the above range, not only the temperature of the middle region of the seed crystal 20 can be improved, but also the silicon carbide atmosphere at the middle position of the accommodation cavity 11 can be guided, so that the silicon carbide atmosphere can be smoothly transported to the seed crystal 20, while preventing the vertical transmission of the silicon carbide atmosphere at the middle position of the accommodation cavity 11 from causing the silicon carbide single crystal in the middle region of the seed crystal 20 to grow too fast and too large in size, thereby forming a silicon carbide single crystal with uniform size distribution and low dislocation density at the seed crystal 20.

[0042] In a further embodiment, the ratio of the bottom surface to the top surface of the flow guide 32 is any value in the range of 0-0.5, i.e. the ratio of the bottom surface to the top surface of the flow guide 32 can be 0, 0.1, 0.2, 0.3, 0.4 or 0.5, or any value in the range of 0-0.5. In the embodiment, by setting the ratio of the bottom surface to the top surface of the flow guide 32 in the above range, the inclination angle of the side wall of the flow guide 32 is adjusted, thereby adjusting the distribution state of the silicon carbide single crystal at the seed crystal 20, which can increase the temperature of the middle region of the seed crystal 20 and reduce the thermal stress of the silicon carbide single crystal in the initial growth stage, thereby reducing the dislocation density of the silicon carbide single crystal.

[0043] In a further embodiment, the top surface of the flow guide 32 is spaced apart from the bottom surface of the seed crystal 20 by a predetermined distance, and the predetermined distance is any value in the range of 70mm-160mm, i.e. the spacing distance between the top surface of the flow guide 32 and the bottom surface of the seed crystal 20 can be 70mm, 80mm, 90mm, 100mm, 110mm, 120mm, 130mm, 140mm, 150mm or 160mm, or any value in the range of 70mm-160mm. In the embodiment, by setting the top surface of the flow guide 32 apart from the bottom surface of the seed crystal 20 by the above predetermined distance, not only the transmission efficiency of the silicon carbide atmosphere in the middle region of the accommodation cavity 11 can be improved, but also the silicon carbide atmosphere can be transported to the middle region of the seed crystal 20, thereby growing a silicon carbide single crystal with uniform distribution in the seed crystal 20.

[0044] In a further embodiment, the flow guide 32 includes a shaped cross-sectional area 321 formed on its sidewalls, which gradually expands upward from the bottom. The flow guide 32 also includes a guide portion located at the top of the shaped cross-sectional area 321 and extending vertically. The ratio of the height of the guide portion to the height of the flow guide 32 is any value between 0.3 and 0.5, that is, the ratio of the height of the guide portion to the height of the flow guide 32 can be 0.3, 0.35, 0.4, 0.45, or 0.5, or any value between 0.3 and 0.5. By configuring the flow guide 32 with the shaped cross-sectional area 321 and the guide portion located at the top of the shaped cross-sectional area 321 and extending vertically, it can not only guide the silicon carbide atmosphere but also prevent the formation of a thermal junction at the top of the flow guide 32, which would lead to increased thermal stress. This further reduces the dislocation density of the silicon carbide single crystal and improves the growth quality of the silicon carbide single crystal.

[0045] In a further embodiment, the height of the guide portion is any value between 0 and 30 mm, that is, the height of the guide portion can be 0 mm, 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, or 30 mm, or any value between 0 and 30 mm. In this embodiment, by setting the height of the guide portion to any value between 0 and 30 mm, a further flow guide portion 322 is formed on the top of the irregular cross-section region 321, so that the formed silicon carbide atmosphere can flow sequentially through the sidewall of the irregular cross-section region 321 and the sidewall of the flow guide portion 322, reducing the flow resistance during the silicon carbide atmosphere transmission process, and preventing the silicon carbide atmosphere from forming a hot junction in the flow guide portion 32, thereby further improving the temperature distribution uniformity at the seed crystal 20, reducing the thermal stress of silicon carbide single crystal growth, and thus reducing the growth dislocation density of silicon carbide single crystal.

[0046] like Figure 2 As shown, in a preferred embodiment, the height of the guide portion is 0 mm and the width ratio of the bottom surface to the top surface of the guide member 32 is 0. That is, the guide member 32 of the graphite structure 30 in the crucible device 100 has a conical structure. The silicon carbide atmosphere generated by the thermal sublimation of silicon carbide powder 40 only flows through the sidewall of the irregular cross-section region 321 in the guide member 32, and finally grows a silicon carbide single crystal with uniform crystal arrangement and low dislocation density at the seed crystal 20, thereby further improving the growth quality of silicon carbide single crystal.

[0047] In a further embodiment, the ratio of the height of the vertical portion 31 to the height of the silicon carbide powder 40 is any value between 1 and 1.3, that is, the ratio of the height of the vertical portion 31 to the height of the silicon carbide powder 40 can be 1, 1.1, 1.2, or 1.3, or any value between 1 and 1.3. In this embodiment, the height of the vertical portion 31 is set within the above range, that is, the height of the vertical portion 31 can be the same as the height of the silicon carbide powder 40, or it can be higher than the height of the silicon carbide powder 40, so that the guide element 32 is always located above the silicon carbide powder 40, which facilitates the flow and transmission of the silicon carbide atmosphere generated after the silicon carbide powder 40 sublimates, that is, the silicon carbide atmosphere is transported from the bottom of the guide element 32 along the side wall of the irregular cross-section region 321 and the side wall of the guide portion 322 toward the seed crystal 20 (refer to...). Figure 6 ), to transport the central silicon carbide atmosphere vertically upward (refer to Figure 5 The silicon carbide atmosphere is guided to both sides by the graphite structure 30, which reduces the flow rate of the silicon carbide atmosphere in the center, prevents the silicon carbide single crystal at the center of the seed crystal 20 from growing too fast, avoids the crystal from cracking due to excessive convexity, and further improves the growth quality of the silicon carbide single crystal.

[0048] In a further embodiment, the tantalum-containing coating material can be either tantalum or tantalum carbide, that is, the tantalum-containing coating material on the surface of the graphite structure 30 can be either tantalum or tantalum carbide. In this embodiment, by coating the surface of the graphite structure 30 with a tantalum-containing coating, carbon particles are prevented from being generated by etching of the graphite structure 30 in the silicon carbide atmosphere during the growth of silicon carbide single crystals. This reduces the presence of graphite particles in the silicon carbide atmosphere due to the graphitization of powder, further reducing carbon encapsulation defects in the silicon carbide single crystal and improving the quality of the silicon carbide single crystal.

[0049] In a further embodiment, the graphite structure 30 is made of isostatically pressed graphite. By setting the graphite structure 30 to isostatically pressed graphite, not only can the thermal stability and thermal conductivity of the graphite structure 30 be improved, ensuring that the graphite structure 30 does not deform or decompose under high-temperature environments, maintaining the stability of the silicon carbide single crystal growth process, and reducing temperature field fluctuations and crystal defects caused by structural changes, but the graphite structure 30 also has high thermal conductivity, providing a uniform temperature field, optimizing the transport and deposition path of the silicon carbide atmosphere, and improving the uniformity and quality of silicon carbide single crystal growth. Furthermore, due to its dense internal structure, isostatically pressed graphite still has high compressive and flexural strength at high temperatures, providing reliable structural support and preventing the graphite structure 30 from cracking or deforming due to thermal or mechanical stress, ensuring the long-term stable operation of the crucible device 100. Here, the material of the crucible device 100 can be isostatically pressed graphite.

[0050] In a further embodiment, the width of the vertical portion 31 is any value within a range of 30mm-80mm, and the width of the accommodating cavity 11 is any value within a range of 200mm-250mm, i.e. the width of the vertical portion 31 can be 30mm, 40mm, 50mm, 60mm, 70mm or 80mm, or any value within a range of 30mm-80mm, and the width of the accommodating cavity 11 can be 200mm, 210mm, 220mm, 230mm, 240mm or 250mm, or any value within a range of 200mm-250mm. By setting the width of the vertical portion 31 and the width of the accommodating cavity 11 within the above corresponding ranges, the vertical portion 31 of the graphite structure 30 can heat the silicon carbide powder 40 at the central position of the accommodating cavity 11, which not only improves the sublimation efficiency of the silicon carbide powder 40 and the growth efficiency of the silicon carbide single crystal, but also prevents the silicon carbide powder 40 at the central position from generating carbon-wrapped defects and improves the growth quality of the silicon carbide single crystal.

[0051] The present application will be further described in detail with reference to specific embodiments.

[0052] Embodiment 1

[0053] The ratio of the top surface of the flow guide 30 to the width of the seed crystal 20 of the crucible device 100 is 0.5, the ratio of the vertical portion 31 to the diameter of the accommodating cavity 11 is 0.3, and the ratio of the bottom surface to the top surface of the flow guide 30 is 0, i.e. the flow guide 30 has a conical structure. The temperature field of the crucible device 100 with the conical flow guide 30 is tested, and the temperature field distribution is shown in FIG. 2. Figure 4

[0054] As shown in FIG. 3, the temperature at the upper portion of the flow guide in the crucible device is higher than the temperature at the same position in the prior art (see FIG. 1), which increases the temperature in the middle region of the seed crystal, ensures the axial growth temperature gradient, reduces the radial temperature gradient at the seed crystal, and thus reduces the through-type dislocations caused by thermal stress in the initial stage of crystal growth. Figure 4 Figure 3

[0055] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but as long as the combinations of the technical features do not contradict, they should be considered within the scope of the present disclosure.

[0056] ​​​The above-described embodiments only express several implementation manners of the utility model, the description is more specific and detailed, but can not therefore be understood as the limitation of the utility model patent range. It should be pointed out that for ordinary skilled person in the art, without departing from the utility model concept, several modifications and improvements can be made, which belong to the protection range of the utility model. Therefore, the protection range of the utility model patent should be subject to the appended claims.

Claims

1. A crucible apparatus for silicon carbide single crystal growth, characterized in that, The application relates to a crucible device, comprising: a crucible, in which an accommodating cavity for placing silicon carbide powder is formed; a seed crystal located at the top of the crucible; a graphite structure located in the accommodating cavity, the graphite structure comprising a vertical part penetrating the silicon carbide powder and a flow guide located at the top of the vertical part, the flow guide being arranged such that the side wall thereof forms a shape gradually expanding from the bottom upwards; wherein the width ratio of the top surface of the flow guide to the seed crystal is any value in the range of 0.3-0.8, the diameter ratio of the vertical part to the accommodating cavity is any value in the range of 0.1-0.4, and the surfaces of the vertical part and the flow guide are coated with a tantalum-containing coating.

2. The crucible device according to claim 1, wherein the width ratio of the bottom surface of the flow guide to the top surface is any value in the range of 0-0.

5.

3. The crucible device according to claim 2, wherein the top surface of the flow guide is spaced apart from the bottom surface of the seed crystal by a preset distance, and the preset distance is any value in the range of 70mm-160mm.

4. The crucible apparatus of claim 3, wherein the flow guide comprises a side wall forming a special-shaped cross-section area gradually expanding from the bottom upwards, and the flow guide further comprises: a guide part located at the top of the special-shaped cross-section area and extending in the vertical direction, and the height ratio of the guide part to the flow guide is any value in the range of 0.3-0.

5.

5. The crucible device according to claim 4, wherein the height of the guide part is any value in the range of 0-30mm.

6. The crucible device according to any one of claims 1-5, wherein the height ratio of the vertical part to the silicon carbide powder is any value in the range of 1-1.

3.

7. The crucible device according to claim 6, wherein the material of the tantalum-containing coating is any one of tantalum or tantalum carbide.

8. The crucible device according to claim 7, wherein the material of the graphite structure is isostatic graphite.

9. The crucible device according to claim 8, wherein the width of the vertical part is any value in the range of 30mm-80mm.

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