Silicon carbide crystal growth apparatus

Abstract

This invention provides a silicon carbide crystal growth apparatus, relating to the field of semiconductor technology. The apparatus includes a partition below silicon carbide powder, with a receiving cavity formed below the partition and at least one ring of through holes along the edge of the partition. A pressing structure is positioned above the silicon carbide powder corresponding to the through holes. This pressing structure presses down on the silicon carbide powder near the crucible sidewall during crystal growth, forcing it to pass through the through holes and fall into the receiving cavity. This creates a gap between the crucible sidewall and the silicon carbide powder away from it. Without the obstruction of the silicon carbide powder near the crucible sidewall, the heat from the crucible can be better transferred to the powder away from the sidewall, promoting sublimation of the silicon carbide powder in the corresponding area, thereby improving the utilization rate of the silicon carbide powder and increasing the crystal growth size.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically, to a silicon carbide crystal growth apparatus. Background Technology

[0002] Silicon carbide (SiC) crystal is a typical wide-bandgap semiconductor material and one of the representatives of the third generation of semiconductor materials after silicon and gallium arsenide. SiC crystal possesses excellent properties such as high thermal conductivity, high breakdown field strength, and high saturated electron mobility, making it a popular material for fabricating high-temperature, high-frequency, high-power, and radiation-resistant devices. Currently, the main methods for growing SiC crystals include physical vapor transport (PVT), liquid phase epitaxy (LPE), and chemical vapor deposition (CVD). Among these, PVT is the most mature method. It involves heating SiC powder in a crucible, causing the powder to sublimate and crystallize at a seed crystal at a lower temperature, thus achieving crystal growth.

[0003] However, existing silicon carbide crystal growth devices based on physical vapor transport generally suffer from insufficient utilization of powder materials. Summary of the Invention

[0004] The present invention aims to provide a silicon carbide crystal growth apparatus that enables heat to reach silicon carbide powder away from the crucible sidewall more effectively, thereby promoting the sublimation of silicon carbide powder in the corresponding area and improving the utilization rate of silicon carbide powder.

[0005] The embodiments of the present invention can be implemented as follows: This invention provides a silicon carbide crystal growth apparatus, comprising: A crucible, wherein a seed crystal is provided on the inner side of the top wall of the crucible; A partition is located inside the crucible and spaced apart from the bottom wall of the crucible. The partition, the top wall of the crucible, and the peripheral wall of the crucible together form a growth cavity for filling silicon carbide powder. The partition, the bottom wall of the crucible, and the side wall of the crucible together form a receiving cavity. The edge of the partition is provided with a plurality of through holes arranged at intervals along the circumferential direction. A pressing structure is disposed within the growth chamber and above the silicon carbide powder. Along the height direction of the crucible, the pressing structure corresponds to a plurality of through holes. The pressing structure is used to press down the silicon carbide powder near the sidewall of the crucible during crystal growth, so as to force the silicon carbide powder near the sidewall of the crucible to pass through the plurality of through holes and fall into the receiving chamber.

[0006] In an optional embodiment, the pressure structure is a ring of tantalum carbide particles.

[0007] In an optional embodiment, the upper surface of the tantalum carbide particles is located on the same horizontal plane as the upper surface of the silicon carbide powder.

[0008] In an optional embodiment, the pressing structure is a pressing ring, which is made of tantalum carbide or has a tantalum carbide layer on its outer surface.

[0009] In an optional embodiment, the lower pressure ring is connected to a lifting rod, the lifting rod is made of tantalum carbide or the outer surface of the lifting rod is provided with a tantalum carbide layer, and the lifting rod passes through the top wall of the crucible.

[0010] In an optional embodiment, a flow guide tube is provided on the inner side wall of the crucible, the lifting rod passes through the flow guide tube, and the lower pressure ring is located below the flow guide tube.

[0011] In an optional embodiment, the through hole is frustum-shaped and the diameter gradually decreases from top to bottom.

[0012] In an optional embodiment, the diameter of the bottom end of the through hole is greater than or equal to 2.1 mm, and the diameter of the top end of the through hole is less than or equal to 2.5 mm.

[0013] In an optional embodiment, the partition is supported on the bottom wall of the crucible by a pad.

[0014] In an optional embodiment, the silicon carbide powder filling the growth chamber is divided into an upper layer and a lower layer, wherein the mesh size of the silicon carbide powder in the upper layer is greater than that in the lower layer.

[0015] The beneficial effects of the silicon carbide crystal growth apparatus provided in this embodiment of the invention include: This silicon carbide crystal growth apparatus includes a crucible, a partition, and a pressing structure. A seed crystal is disposed on the inner side of the top wall of the crucible. The partition is located inside the crucible and is spaced apart from the bottom wall. The partition, the top wall of the crucible, and the peripheral wall of the crucible together form a growth cavity for filling with silicon carbide powder. The partition, the bottom wall of the crucible, and the side walls of the crucible together form a receiving cavity. Multiple through holes are arranged circumferentially along the edge of the partition. The pressing structure is disposed inside the growth cavity and above the silicon carbide powder. Along the height of the crucible, the pressing structure corresponds to the multiple through holes.

[0016] The pressure structure is used to press down silicon carbide powder near the crucible sidewall during crystal growth, forcing the silicon carbide powder near the crucible sidewall to fall into the receiving cavity through multiple through holes. This creates a gap between the crucible sidewall and the silicon carbide powder away from the crucible sidewall. Since there is no obstruction from the silicon carbide powder near the crucible sidewall, the heat of the crucible can be better transferred to the silicon carbide powder away from the crucible sidewall, thereby promoting the sublimation of the silicon carbide powder in the corresponding area, thus improving the utilization rate of silicon carbide powder and increasing the growth size of the crystal. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the silicon carbide crystal growth apparatus provided in the first embodiment of the present invention before the pressing structure is pressed down; Figure 2 This is a schematic diagram of the structure of the partition of the silicon carbide crystal growth apparatus provided in the first embodiment of the present invention; Figure 3 This is a schematic diagram of the silicon carbide crystal growth apparatus provided in the first embodiment of the present invention when the pressure structure is pressed down; Figure 4 This is a schematic diagram of the silicon carbide crystal growth apparatus provided in the second embodiment of the present invention before the pressing structure is pressed down; Figure 5 This is a schematic diagram of the silicon carbide crystal growth apparatus provided in the second embodiment of the present invention when the pressure structure is pressed down; Figure 6 This is a schematic diagram of the silicon carbide crystal growth apparatus provided in the second embodiment of the present invention after being pressed down by the pressing structure.

[0019] Icons: 100-Crucible; 102-Growth chamber; 104-Containing chamber; 110-Seed crystal; 200-Separator; 202-Through hole; 210-Padded block; 300-Pressure structure; 310-Lifting rod; 400-Guide tube; 500-Silicon carbide powder. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0022] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0023] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0024] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0025] It should be noted that, where there is no conflict, the features in the embodiments of the present invention can be combined with each other.

[0026] In existing silicon carbide crystal growth apparatuses based on physical vapor transport (PVT), the heating structure is typically located on the periphery of the crucible sidewall, indirectly heating the silicon carbide powder inside the crucible by heating the crucible itself. This heating method inevitably results in the silicon carbide powder near the crucible sidewall (i.e., the edge region) receiving more heat and achieving a higher degree of sublimation, while the silicon carbide powder farther from the crucible sidewall (i.e., the central region) receives less heat and achieves a lower degree of sublimation due to the obstruction of the silicon carbide powder near the crucible sidewall. This leads to lower utilization of the silicon carbide powder and limits the crystal growth size.

[0027] To address the above issues, this invention provides a silicon carbide crystal growth apparatus. A partition is positioned below the silicon carbide powder, forming a receiving cavity below the partition. At least one ring of through holes is provided along the edge of the partition. A pressing structure is positioned above the silicon carbide powder at the location corresponding to the through holes. This pressing structure can press down on the silicon carbide powder near the crucible sidewall during crystal growth (e.g., in the middle to later stages of crystal growth), forcing the powder to pass through multiple through holes and fall into the receiving cavity. This creates a gap between the crucible sidewall and the silicon carbide powder away from it. Since there is no obstruction from the silicon carbide powder near the crucible sidewall, the heat from the crucible can be better transferred to the powder away from it, thereby promoting sublimation of the silicon carbide powder in the corresponding area, improving the utilization rate of the silicon carbide powder, and increasing the crystal growth size.

[0028] The following section, with reference to the accompanying drawings, details the overall structure, working principle, and technical effects of this silicon carbide crystal growth apparatus.

[0029] First embodiment: Please refer to Figure 1 and Figure 2 This invention provides a silicon carbide crystal growth apparatus for growing silicon carbide crystals. The silicon carbide crystal growth apparatus includes a crucible 100, a partition 200, a pressing structure 300, and a heater (not shown in the figure).

[0030] The heater is located on the outer periphery of the side wall of the crucible 100 and is used to heat the crucible 100. A seed crystal 110 is provided on the inner side of the top wall of the crucible 100 to serve as the basis for the growth of silicon carbide crystals.

[0031] The partition 200 is located inside the crucible 100 and is spaced apart from the bottom wall of the crucible 100. The partition 200, the top wall of the crucible 100, and the peripheral wall of the crucible 100 together form a growth cavity 102. The growth cavity 102 is used to fill silicon carbide powder 500. The partition 200, the bottom wall of the crucible 100, and the side wall of the crucible 100 together form a receiving cavity 104.

[0032] The partition 200 can be installed in the crucible 100 in different ways as needed. In this embodiment, the partition 200 is supported on the bottom wall of the crucible 100 by the pad 210 to facilitate installation and disassembly.

[0033] The edge of the partition 200 is provided with a plurality of through holes 202 arranged at intervals along the circumferential direction. In this embodiment, the through holes 202 are provided in at least one ring. In other embodiments, the through holes 202 may also be provided in two or three rings.

[0034] The shape and size of the through-hole 202 can be set according to actual needs. In this embodiment, the through-hole 202 is frustum-shaped and the diameter gradually decreases from top to bottom. Further, the diameter of the bottom end of the through-hole 202 is greater than or equal to 2.1 mm, and the diameter of the top end of the through-hole 202 is less than or equal to 2.5 mm. That is, in this embodiment, the diameter of the through-hole 202 is approximately 2.3 mm. This size of the through-hole 202 can better match the size of the silicon carbide powder 500, so that the silicon carbide powder 500 is less likely to fall through the through-hole 202 into the receiving cavity 104 before crystal growth, and allows the silicon carbide powder 500 to fall through the through-hole 202 into the receiving cavity 104 during crystal growth.

[0035] An annular flow guide tube 400 is provided on the inner side wall of the crucible 100. The flow guide tube 400 is used to guide the long crystal gas phase formed by the sublimation of silicon carbide powder 500 to flow efficiently to the seed crystal 110, so as to accelerate the growth of silicon carbide crystal.

[0036] Please refer to again Figure 1 The pressing structure 300 is disposed within the growth chamber 102 and located above the silicon carbide powder 500. Along the height direction of the crucible 100, the pressing structure 300 corresponds to a plurality of through holes 202. The pressing structure 300 is used to press down the silicon carbide powder 500 near the sidewall of the crucible 100 during crystal growth, so as to force the silicon carbide powder 500 near the sidewall of the crucible 100 to pass through the plurality of through holes 202 and fall into the receiving chamber 104.

[0037] In this embodiment, the pressing structure 300 is a ring of tantalum carbide particles, with the upper surface of the tantalum carbide particles and the upper surface of the silicon carbide powder 500 at the same horizontal plane. Using a ring of tantalum carbide particles as the pressing structure 300 has many advantages. The tantalum carbide will not react with the crystal growth vapor phase formed by the sublimation of the silicon carbide particles, effectively avoiding the introduction of impurities and ensuring crystal quality. Furthermore, the granular tantalum carbide particles can minimize obstruction to the crystal growth vapor phase formed by the sublimation of the silicon carbide powder 500, ensuring the crystal growth rate. Moreover, using a ring of tantalum carbide particles as the pressing structure 300 is simple in structure, requires no external power, and can effectively press down the silicon carbide powder 500 in the edge region during crystal growth solely by its own gravity. It should be noted that in other embodiments, tantalum carbide particles can also be filled at the edge of the upper surface of the silicon carbide powder 500.

[0038] The working principle and process of the silicon carbide crystal growth apparatus in this embodiment are as follows: Before crystal growth, the partition 200 is supported on the bottom wall of the crucible 100 by the pad 210. Then, silicon carbide powder 500 is filled in. When filling the silicon carbide powder 500, it can be filled in layers. The mesh size of the upper layer of silicon carbide powder 500 (optionally greater than 8 mesh) is greater than that of the lower layer of silicon carbide powder 500 (optionally 8 mesh). Since the initial silicon carbide powder 500 has a high density and weight, and strong load-bearing capacity, it will not fall into the receiving cavity 104 through the through hole 202. Even if a small number of particles fall, it will not have a significant impact, because the through hole 202 ensures the sublimation channel. After the silicon carbide powder 500 is filled, a ring of tantalum carbide particles is filled at the top edge of the silicon carbide powder 500 so that the tantalum carbide particles are flush with the upper surface of the silicon carbide powder 500 (i.e., located on the same horizontal plane), and the tantalum carbide particles correspond to a ring of through holes 202 in the height direction of the crucible 100.

[0039] After filling with silicon carbide powder 500 and tantalum carbide particles, the guide tube 400 and the top wall of the crucible 100 with the seed crystal 110 are installed. The heater is started, and the silicon carbide powder 500 begins to sublimate under heat, crystallizing on the seed crystal 110 to form silicon carbide crystals. As the crystals continue to grow, the silicon carbide powder 500 gradually becomes loose and porous, its weight and density gradually decrease, and its load-bearing capacity becomes weaker and weaker. The silicon carbide powder 500 near the side wall of the crucible 100 begins to fall into the receiving cavity 104 through the through hole 202 under its own gravity and the downward pressure of the tantalum carbide particles (see...). Figure 3 This design allows for the formation of a gap between the sidewall of crucible 100 and the silicon carbide powder 500 located away from the sidewall. Since there is no obstruction from the silicon carbide powder 500 near the sidewall, the heat from crucible 100 can be better transferred to the silicon carbide powder 500 located away from the sidewall, thereby promoting the sublimation of the silicon carbide powder 500 in the corresponding region (i.e., the central region), thus improving the utilization rate of the silicon carbide powder 500 and increasing the crystal growth size. Simultaneously, it can effectively adjust the carbon-silicon ratio within crucible 100, effectively reducing the carbonization of the silicon carbide powder 500, thereby reducing crystal defects.

[0040] Second embodiment: Please refer to Figure 4 The silicon carbide crystal growth apparatus provided in this embodiment is basically the same as the silicon carbide crystal growth apparatus provided in the first embodiment in terms of overall structure, working principle and technical effect. The difference lies in the specific form of the pressure structure 300.

[0041] In this embodiment, the pressure structure 300 is a pressure ring, which is made of tantalum carbide or has a tantalum carbide layer on its outer surface. The pressure ring is located below the guide tube 400. Furthermore, the pressure ring is connected to a lifting rod 310, which is also made of tantalum carbide or has a tantalum carbide layer on its outer surface. The lifting rod 310 passes through the top wall of the guide tube 400 and the crucible 100, with its bottom end connected to the pressure ring and its top end extending out of the crucible 100 and connected to an external power source, so that the pressure ring can be raised and lowered under the drive of the external power source.

[0042] The difference between the working principle and process of the silicon carbide crystal growth apparatus in this embodiment and that in the first embodiment is that, in this embodiment, tantalum carbide particles are not loaded. Instead, at a suitable time point during crystal growth (generally the middle and late stages of crystal growth), the lifting rod 310 drives the pressure ring to descend from a position near the guide cylinder 400, pressing down on the silicon carbide powder 500 near the side wall of the crucible 100. This forces the silicon carbide powder 500 near the side wall of the crucible 100 to pass through the through hole 202 and fall into the receiving cavity 104 (see...). Figure 5 Compared to the first embodiment, the timing of the downward pressure of the downward pressure structure 300 in this embodiment can be actively controlled, and it can be pressed down multiple times as needed to ensure the pressing effect. After pressing down, the lifting rod 310 can drive the downward pressure ring to rise and return to a position close to the guide tube 400 (see...). Figure 6 When pressure is not required, the pressure ring is positioned 400mm close to the guide tube to minimize obstruction to the crystal growth gas phase.

[0043] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A silicon carbide crystal growth apparatus, characterized in that, include: A crucible (100) having a seed crystal (110) disposed on the inner side of its top wall. A partition (200) is located inside the crucible (100) and spaced apart from the bottom wall of the crucible (100). The partition (200), the top wall of the crucible (100), and the peripheral wall of the crucible (100) together form a growth cavity (102). The growth cavity (102) is used to fill silicon carbide powder (500). The partition (200), the bottom wall of the crucible (100), and the side wall of the crucible (100) together form a receiving cavity (104). The edge of the partition (200) is provided with a plurality of through holes (202) arranged at intervals along the circumferential direction. A pressing structure (300) is disposed in the growth chamber (102) and above the silicon carbide powder (500). Along the height direction of the crucible (100), the pressing structure (300) corresponds to a plurality of through holes (202). The pressing structure (300) is used to press down the silicon carbide powder (500) close to the side wall of the crucible (100) during crystal growth, so as to force the silicon carbide powder (500) close to the side wall of the crucible (100) to pass through the plurality of through holes (202) and fall into the receiving chamber (104).

2. The silicon carbide crystal growth apparatus according to claim 1, characterized in that, The pressure structure (300) is a ring of tantalum carbide particles.

3. The silicon carbide crystal growth apparatus according to claim 2, characterized in that, The upper surface of the tantalum carbide particles is on the same horizontal plane as the upper surface of the silicon carbide powder (500).

4. The silicon carbide crystal growth apparatus according to claim 1, characterized in that, The pressing structure (300) is a pressing ring, which is made of tantalum carbide or has a tantalum carbide layer on its outer surface.

5. The silicon carbide crystal growth apparatus according to claim 4, characterized in that, The lower pressure ring is connected to a lifting rod (310), which is made of tantalum carbide or has a tantalum carbide layer on its outer surface. The lifting rod (310) passes through the top wall of the crucible (100).

6. The silicon carbide crystal growth apparatus according to claim 5, characterized in that, A flow guide tube (400) is provided on the inner side wall of the crucible (100), the lifting rod (310) passes through the flow guide tube (400), and the lower pressure ring is located below the flow guide tube (400).

7. The silicon carbide crystal growth apparatus according to any one of claims 1-6, characterized in that, The through hole (202) is frustum-shaped and the diameter gradually decreases from top to bottom.

8. The silicon carbide crystal growth apparatus according to claim 7, characterized in that, The diameter of the bottom end of the through hole (202) is greater than or equal to 2.1 mm, and the diameter of the top end of the through hole (202) is less than or equal to 2.5 mm.

9. The silicon carbide crystal growth apparatus according to claim 1, characterized in that, The partition (200) is supported on the bottom wall of the crucible (100) by a pad (210).

10. The silicon carbide crystal growth apparatus according to claim 1, characterized in that, The silicon carbide powder (500) filled in the growth chamber (102) is divided into an upper layer and a lower layer. The mesh size of the silicon carbide powder (500) in the upper layer is greater than that in the lower layer.

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