Crystal growth apparatus and crystal growth method
By setting up heat-insulating baffles and rotatable heat-insulating plates in the crucible to control the connection and closure of the flow holes, the problem of silicon and carbon component enrichment during silicon carbide crystal growth was solved, carbon encapsulation and seed crystal sublimation defects were alleviated, the process window was broadened, and the industrialization of silicon carbide crystals was promoted.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHAANXI LICHUANG JINGYUAN SEMICONDUCTOR TECHNOLOGY CO LTD
- Filing Date
- 2026-03-24
- Publication Date
- 2026-06-05
AI Technical Summary
The existing PVT method has problems with the enrichment of silicon and carbon components in the early and middle stages of silicon carbide crystal growth, resulting in defects such as carbon encapsulation and seed crystal sublimation. The process window is narrow, which is not conducive to industrialization.
A heat-insulating baffle plate and rotatable first and second heat-insulating plates are set in the crucible. By controlling the connection and closure of the flow holes, a heat-insulating and sealing structure is formed to separate the powder placement area and the crystal growth area, control the atmosphere delivery, and prevent the transport of carbon-rich components.
It effectively alleviates the carbon encapsulation problem, improves crystal quality, and broadens the process window, which is conducive to the industrialization and promotion of silicon carbide crystals.
Smart Images
Figure CN122147502A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of crystal growth technology, and more specifically, to a crystal growth apparatus and a crystal growth method. Background Technology
[0002] In the field of crystal growth, physical vapor transport (PVT) is the mainstream technology for growing high-quality single crystals such as silicon carbide. The basic principle of PVT is to sublimate SiC powder into a gas phase at a high temperature (above 2000°C), and then transport the sublimated atmosphere through convection and diffusion. During the transport process, multiple round-trip chemical reactions occur, and finally, SiC single crystals are formed by sublimation on an existing seed crystal.
[0003] During crystal growth, the sublimation of silicon carbide powder is related to temperature and furnace pressure, with temperature having the greatest impact. Higher temperatures result in faster sublimation and crystal growth. In the PVT process, as the heating power increases, the temperature inside the crucible gradually rises, and the furnace pressure is matched to the temperature change. The commonly used temperature range for growing 4H crystals using the normal PVT method is 2200-2400℃. However, when the temperature rises above 1800℃, silicon carbide powder begins to participate in sublimation. In the initial sublimation atmosphere, the silicon content is relatively high, which can easily cause defects and changes in crystal form during the early stages of crystal growth. Controlling the furnace pressure can have a certain effect on suppressing atmosphere transport, but the suppression effect is limited.
[0004] Moreover, due to the low thermal conductivity of silicon carbide powder caused by its porosity, the temperature of the crucible edge closer to the heater is higher than that of the center region during the crystal growth process. The powder at the edge sublimates before the powder at the center. The remaining carbon-rich components are transported upwards, and the sublimation atmosphere is rich in carbon, which can easily lead to carbon encapsulation in the middle and later stages of crystal growth, and even cause fatal defects such as microtubes in the edge region.
[0005] In addition, conventional seed crystals are usually bonded to the base, and the seed crystal and the powder heating and sublimation chamber are in the same chamber, which makes the seed crystal easy to sublimate together. Therefore, the requirements for temperature distribution are very high, the process window is very small, which is not conducive to the industrialization and promotion of silicon carbide crystals. Summary of the Invention
[0006] The purpose of this invention is to provide a crystal growth apparatus and a crystal growth method that can solve the problems of silicon and carbon component enrichment in the early and middle stages of crystal growth, effectively alleviate the carbon encapsulation problem, alleviate the seed crystal sublimation problem, broaden the process window, and facilitate the industrialization and promotion of silicon carbide crystals.
[0007] In a first aspect, the present invention provides a crystal growth apparatus, comprising: crucible; A heat insulation baffle is disposed in the middle of the crucible, dividing the crucible into a powder placement area and a crystal growth area. A first flow hole is provided in the central area of the heat insulation baffle, and a second flow hole is provided in the edge area of the heat insulation baffle. A first heat insulation plate is movably disposed on the side of the heat insulation barrier plate away from the powder placement area, and at least covers the central area of the heat insulation barrier plate, and a third flow hole is provided on the first heat insulation plate; The second heat insulation plate is movably disposed on the side of the heat insulation barrier plate away from the powder placement area, and at least covers the edge area of the heat insulation barrier plate, and the second heat insulation plate is provided with a fourth flow hole; A seed crystal holder is disposed on top of the crucible to support the seed crystal; Both the first heat insulation plate and the second heat insulation plate are rotatable relative to the heat insulation barrier plate, so that the third flow hole is selectively connected to the first flow hole, and / or the fourth flow hole is selectively connected to the second flow hole.
[0008] In an optional embodiment, the rotation axis of both the first heat insulation plate and the rotation axis of the second heat insulation plate pass through the center of the heat insulation barrier plate.
[0009] In an optional embodiment, a first actuating rod is provided on the edge of the first heat insulation plate, the first actuating rod passing through the side wall of the crucible and extending out of the crucible; The edge of the second heat insulation plate is provided with a second actuating rod, which passes through the side wall of the crucible and extends out of the crucible.
[0010] In an optional embodiment, the side wall of the crucible is provided with a clearance hole, the first actuating rod and the second actuating rod both pass through the clearance hole, and the first actuating rod is provided with a first shielding plate, the second actuating rod is provided with a second shielding plate, the first shielding plate and the second shielding plate are both attached to the outer side wall of the crucible and block the clearance hole.
[0011] In an optional embodiment, there are multiple first flow holes, which are evenly distributed radially around the center of the heat insulation barrier plate; there are multiple third flow holes, which are configured to communicate with each of the multiple first flow holes respectively.
[0012] In an optional embodiment, each of the first flow holes is triangular, and the apex angle of each first flow hole near the center of the heat insulation barrier is θ, the included angle formed by the sides of adjacent first flow holes is also θ, and the shape of the third flow hole is adapted to the shape of the first flow hole.
[0013] In an optional embodiment, there are multiple second flow holes, each comprising multiple rows of radially distributed holes, each row of holes including at least one second flow hole, and the multiple rows of holes being uniformly radially distributed around the center of the heat insulation barrier plate; there are multiple fourth flow holes, each configured to communicate with one of the multiple second flow holes respectively.
[0014] In an optional embodiment, the second flow hole is a circular hole, and the shape of the fourth flow hole is adapted to the shape of the second flow hole.
[0015] In an optional embodiment, the crucible includes a crucible body, a crucible inner ring, and a growth ring. The crucible inner ring is detachably disposed on the crucible body, the growth ring is detachably disposed on the crucible inner ring, the seed crystal holder is disposed on the growth ring, and the heat insulation baffle is integrally disposed on the inner sidewall of the crucible inner ring.
[0016] Secondly, the present invention provides a crystal growth method applicable to the aforementioned crystal growth apparatus, the method comprising: Place the silicon carbide powder into the powder placement area of the crucible; Before crystal growth, rotate the first heat insulation plate and the second heat insulation plate so that the third flow hole on the first heat insulation plate is misaligned and closed with the first flow hole on the heat insulation barrier plate, and the fourth flow hole on the second heat insulation plate is misaligned and closed with the second flow hole on the heat insulation barrier plate. When crystal growth begins, rotate the first heat insulation plate and the second heat insulation plate again so that the third flow hole is connected to the first flow hole and the fourth flow hole is connected to the second flow hole. After the crystal growth time is preset, the second heat insulation plate is rotated again to make the fourth flow hole close in a staggered manner with the second flow hole.
[0017] The beneficial effects of the embodiments of the present invention include: The crystal growth apparatus and method provided in this invention feature a heat-insulating baffle plate in the center of the crucible. The heat-insulating baffle plate has a first flow hole in its central region and a second flow hole in its edge region, achieving heat insulation. Simultaneously, a first heat-insulating plate and a second heat-insulating plate are positioned on the side of the heat-insulating baffle plate away from the powder placement area. The first and second heat-insulating plates respectively cover at least the central and edge regions of the heat-insulating baffle plate and are respectively provided with only a third and a fourth flow hole. A seed crystal holder is positioned at the top of the crucible to support the seed crystal.
[0018] In actual crystal growth, this crystal growth apparatus, by rotating the first and second heat insulation plates, allows the third and first flow holes to close in a staggered manner before crystal growth, and the fourth and second flow holes to close in a staggered manner as well. This enables the first, second, and heat insulation plates and the heat insulation barrier plate to form a heat insulation and sealing structure, blocking the sublimated gas in the powder placement area during the heating process, preventing defects and crystal form changes caused by the sublimated gas in the early stages of crystal growth. At the beginning of crystal growth, the third and first flow holes can be connected, and the fourth and second flow holes can be connected, fully opening the upper and lower atmosphere transport channels. In the middle and later stages of crystal growth, the fourth and second flow holes can be closed in a staggered manner, hindering the upward transport of carbon-rich components in the edge region, mitigating defects caused by carbon inclusions, and improving crystal quality.
[0019] Compared to existing technologies, the crystal growth apparatus provided in this invention, through the arrangement of a first heat insulation plate, a second heat insulation plate, and a heat insulation barrier plate, and by rotating them, determines whether each flow path is connected or not. This solves the problem of silicon and carbon component enrichment in the early and middle stages of crystal growth, effectively alleviating the carbon encapsulation problem. Furthermore, the first heat insulation plate, the second heat insulation plate, and the heat insulation barrier plate can form a heat insulation and sealing structure, dividing the crucible into a hot zone (powder placement zone) and a cold zone (crystal growth zone), alleviating the seed crystal sublimation problem, widening the process window, and facilitating the industrialization and promotion of silicon carbide crystals. Attached Figure Description
[0020] 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.
[0021] Figure 1 This is a schematic diagram of the external structure of the crystal growth apparatus provided in an embodiment of the present invention; Figure 2 A cross-sectional structural diagram of the crystal growth apparatus provided in an embodiment of the present invention from a first-view perspective; Figure 3 This is an exploded structural diagram of the crystal growth apparatus provided in an embodiment of the present invention; Figure 4 A cross-sectional structural diagram of the crystal growth apparatus provided in an embodiment of the present invention from a second perspective; Figure 5 for Figure 2 Schematic diagram of the structure of the heat insulation barrier plate; Figure 6 for Figure 2 A schematic diagram of the structure of the first heat insulation panel; Figure 7 for Figure 2 A schematic diagram of the structure of the second heat insulation board.
[0022] Icons: 100 - Crystal growth apparatus; 110 - Crucible; 111 - Clearance hole; 113 - Crucible body; 115 - Crucible inner ring; 117 - Growth ring; 130 - Heat insulation plate; 131 - First flow hole; 133 - Second flow hole; 135 - Drain hole; 150 - First heat insulation plate; 151 - Third flow hole; 153 - First actuating rod; 155 - First shielding plate; 170 - Second heat insulation plate; 171 - Fourth flow hole; 173 - Second actuating rod; 175 - Second shielding plate; 190 - Seed crystal holder. Detailed Implementation
[0023] 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.
[0024] 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.
[0025] 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.
[0026] 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.
[0027] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.
[0028] As disclosed in the background section, the two main conventional PVT methods are induction heating and resistance heating. The main difference between the two methods is the heating method; their core crucible and crystal growth path structures are essentially the same. In induction or resistance heating, a heat source is provided to the powder, raising its temperature to the sublimation temperature. The sublimated silicon carbide reacts during transport, ultimately depositing onto a seed crystal for growth. Regardless of the growth method, the seed crystal and the powder are both housed within the cavity of a graphite crucible.
[0029] Sublimation of silicon carbide powder is related to temperature and furnace pressure, with temperature having the greatest impact. Higher temperatures result in faster sublimation and crystal growth. In the PVT process, as the heating power increases, the temperature inside the crucible gradually rises, and the furnace pressure is matched to the temperature change. The commonly used temperature range for growing 4H crystals using the normal PVT method is 2200-2400℃. However, when the temperature rises above 1800℃, silicon carbide powder begins to participate in sublimation. In the initial sublimation atmosphere, the silicon content is relatively high, which can easily cause defects and changes in crystal form during the early stages of crystal growth. Controlling the furnace pressure can have a certain effect on suppressing atmosphere transport, but the suppression effect is limited.
[0030] Due to the low thermal conductivity of silicon carbide powder caused by its porosity, the temperature at the crucible edge, closer to the heater, is higher than that at the center during crystal growth. The powder at the edge sublimates before the powder at the center, leaving behind carbon-rich components. As these components are transported upwards, the sublimation atmosphere becomes carbon-rich, easily leading to carbon encapsulation in the later stages of crystal growth and even causing fatal defects such as micropipes in the edge region. To address this issue, existing technologies have employed graphite rings at the edge to block the upward transport of the carbon-rich atmosphere. However, this method is ineffective and cannot precisely control the crystal growth process.
[0031] In crystal growth, seed crystals are typically attached to a graphite substrate, which is then screwed tightly to the crucible to form a sealed space. Because there are no obstructions in this sealed space, the temperature difference between the seed crystal and the powder is very small. For the powder at the bottom to sublimate, this small temperature difference makes it very easy for the seed crystal to sublimate as well. Since the seed crystal is usually only about 500µm thick, poor temperature control can easily cause it to sublimate into holes or completely sublimate. Both hole formation and sublimation in the seed crystal can lead to microtubes or polycrystalline growth, resulting in crystal growth failure. Furthermore, even if the seed crystal is prevented from sublimating, there are strict requirements for its attachment to the substrate. When tiny bubbles form during adhesion, and the temperature inside these bubbles reaches the seed crystal's sublimation temperature, the seed crystal will sublimate within the bubbles, causing numerous back-side sublimation etching pits. These pits are a major cause of microtubes and various defects, severely impacting crystal quality. Therefore, the conventional structure of bonding the seed crystal to the base and the structure of heating and sublimating the seed crystal and powder in one cavity has a number of problems. It has very high requirements for temperature distribution and a very small process window, which is not conducive to the industrialization and promotion of silicon carbide crystals.
[0032] To address the aforementioned problems, embodiments of the present invention provide a novel crystal growth apparatus 100 and a crystal growth method. It should be noted that, unless otherwise specified, the features in the embodiments of the present invention can be combined with each other.
[0033] See Figures 1 to 4 The crystal growth apparatus 100 provided in this embodiment of the invention can solve the problems of silicon and carbon component enrichment in the early and middle stages of crystal growth, effectively alleviate the carbon encapsulation problem, and at the same time alleviate the seed crystal sublimation problem, broaden the process window, and is conducive to the industrialization and promotion of silicon carbide crystals.
[0034] The crystal growth apparatus 100 provided in this embodiment of the invention includes a crucible 110, a heat insulation baffle plate 130, a first heat insulation plate 150, a second heat insulation plate 170, and a seed crystal holder 190. The heat insulation baffle plate 130 is disposed in the middle of the crucible 110, dividing the crucible 110 into a powder placement area and a crystal growth area. A first flow hole 131 is provided in the central area of the heat insulation baffle plate 130, and a second flow hole 133 is provided in the edge area of the heat insulation baffle plate 130. The first heat insulation plate 150 is movably disposed on the side of the heat insulation baffle plate 130 away from the powder placement area, and at least covers the central area of the heat insulation baffle plate 130. A third flow hole 151 is provided on the first heat insulation plate 150. The second heat insulation plate 170 is movably disposed on the side of the heat insulation baffle plate 130 away from the powder placement area, and at least covers the edge area of the heat insulation baffle plate 130. A fourth flow hole 171 is provided on the second heat insulation plate 170. A seed crystal holder 190 is disposed on top of the crucible 110 to support the seed crystal. The first heat insulation plate 150 and the second heat insulation plate 170 are both rotatable relative to the heat insulation barrier plate 130, so that the third flow hole 151 is selectively connected to the first flow hole 131, and / or the fourth flow hole 171 is selectively connected to the second flow hole 133.
[0035] The first heat insulation plate 150 and the second heat insulation plate 170 can both be rotated to open or close the first flow hole 131 and the second flow hole 133. Specifically, during actual crystal growth, by rotating the first heat insulation plate 150 and the second heat insulation plate 170, the third flow hole 151 and the first flow hole 131 can be misaligned and closed before crystal growth, and the fourth flow hole 171 and the second flow hole 133 can be misaligned and closed. This allows the first heat insulation plate 150, the second heat insulation plate 170, and the heat insulation barrier plate 130 to form a heat insulation and sealing structure, blocking the sublimated gas in the powder placement area during the heating process, and preventing the sublimated gas from causing defects and changes in crystal form in the early stage of crystal growth. At the beginning of crystal growth, the third flow hole 151 can be connected to the first flow hole 131, and the fourth flow hole 171 can be connected to the second flow hole 133, so that the upper and lower atmosphere transport channels are fully opened. In the later stages of crystal growth, the fourth flow hole 171 and the second flow hole 133 can be misaligned and closed, hindering the upward transport of carbon-rich components in the edge region, alleviating defects caused by carbon inclusions, and improving crystal quality. Furthermore, the first heat insulation plate 150, the second heat insulation plate 170, and the heat insulation barrier plate 130 can form a heat insulation and sealing structure, which can divide the crucible 110 into a hot zone (powder placement zone) and a cold zone (crystal growth zone), alleviating seed crystal sublimation problems, widening the process window, and facilitating the industrialization and promotion of silicon carbide crystals.
[0036] It should be noted that the crystal growth apparatus 100 provided in this embodiment of the invention is used to grow silicon carbide crystals. The powder placement area can hold silicon carbide powder. Here, the heat insulation baffle 130, together with the first heat insulation plate 150 and the second heat insulation plate 170, can divide the crucible 110 into a hot zone and a cold zone. The hot zone is used for sublimation of the powder, and the cold zone is used for crystal growth. The heat insulation baffle 130, which distinguishes between the hot and cold zones, serves to insulate heat and control the delivery of the sublimation atmosphere. This can solve the problem of uneven sublimation of silicon carbide powder and the problem of difficulty in controlling the seed crystal caused by the seed crystal and powder being in the same chamber.
[0037] In some embodiments, the rotation axis of the first heat insulation plate 150 and the rotation axis of the second heat insulation plate 170 both pass through the center of the heat insulation baffle plate 130. Specifically, the heat insulation baffle plate 130 is disc-shaped, and both the first heat insulation plate 150 and the second heat insulation plate 170 rotate around the center of the heat insulation baffle plate 130, thereby achieving switching between different conduction states. The first heat insulation plate 150 is also disc-shaped and covers the central region of the heat insulation baffle plate 130, while the second heat insulation plate 170 is annular and covers the edge region of the heat insulation baffle plate 130. It should be noted that the center of the first heat insulation plate 150 can be connected to the heat insulation baffle plate 130 via a rotating shaft, thereby ensuring the concentricity of the first heat insulation plate 150 and the heat insulation baffle plate 130. The outer diameter of the second heat insulation plate 170 can be the same as the inner diameter of the corresponding position of the crucible 110. For example, the outer diameter of the second heat insulation plate 170 is the same as the diameter of the heat insulation baffle plate 130, thereby using the inner sidewall of the crucible 110 to radially limit the second heat insulation plate 170.
[0038] In some embodiments, the crucible 110 includes a crucible body 113, a crucible inner ring 115, and a growth ring 117. The crucible inner ring 115 is detachably disposed on the crucible body 113, the growth ring 117 is detachably disposed on the crucible inner ring 115, a seed crystal holder 190 is disposed on the growth ring 117, and a heat insulation baffle plate 130 is integrally disposed on the inner wall of the crucible inner ring 115. Specifically, the crucible body 113 is the lower half of the crucible 110 and is mainly used to load silicon carbide powder. The heating device mainly heats the crucible body 113, making the interior of the crucible body 113 a high-temperature region, which is the main region for heating the silicon carbide powder to sublimation. The crucible inner ring 115 is a connecting structure between the crucible body 113 and the upper growth ring 117, and its designed outer diameter is larger than the outer diameter of the crucible body 113. The heat insulation baffle plate 130 is integrally disposed on the inner wall of the crucible inner ring 115. The growth ring 117 can be a graphite ring, which can support the seed crystal holder 190 and form a cavity for crystal growth.
[0039] Preferably, the upper and lower edges of the crucible inner ring 115 are threaded, allowing for tight connection with the crucible body 113 and the growth ring 117, and facilitating easy assembly and disassembly. The crucible body 113, the crucible inner ring 115, the heat insulation baffle plate 130, the first heat insulation plate 150, and the second heat insulation plate 170 can all be made of graphite. Furthermore, the heat insulation baffle plate 130, the first heat insulation plate 150, and the second heat insulation plate 170 can achieve good heat insulation performance by utilizing their anisotropy. The thickness of the first heat insulation plate 150, the second heat insulation plate 170, and the heat insulation baffle plate 130 is all between 3-5 mm.
[0040] See also Figures 5 to 7 In some embodiments, there are multiple first flow holes 131, which are evenly distributed radially around the center of the heat insulation barrier plate 130; there are multiple third flow holes 151, which are configured to communicate with the multiple first flow holes 131 respectively.
[0041] Furthermore, each first flow hole 131 is triangular, and the apex angle of each first flow hole 131 near the center of the heat insulation baffle plate 130 is θ. The included angle formed by the sides of adjacent first flow holes 131 is also θ. The shape of the third flow hole 151 is adapted to the shape of the first flow hole 131.
[0042] It is worth noting that the first flow hole 131 in the central area of the heat insulation baffle 130 is set as a radial vent hole centered on the center. The first flow hole 131 is triangular, with its apex angle set as θ, and the included angle formed between adjacent first flow holes 131 is also θ. The number of first flow holes 131 is not limited here; for example, the number n of first flow holes 131 can be 18, corresponding to θ = 360 / 2n = 10°. The number n of first flow holes 131 can be set to be between 12 and 36, and n is an even number. The first flow holes 131 are evenly distributed in the central circular area of radius r, where the radius is the two sides of the triangular first flow hole 131, and the base is the line connecting the endpoints of the two sides. Here, the radius r ranges from 50 to 100 mm, while the radius R of the entire heat insulation baffle 130 is between 120 and 170 mm.
[0043] It should be noted that the first heat insulation plate 150 is in the shape of a circular piece and is concentrically distributed in the central area of the heat insulation baffle plate 130. The shape of the first heat insulation plate 150 can be adapted to the circular central area of the heat insulation baffle plate 130. The distribution angle of the third flow hole 151 is consistent with that of the first flow hole 131, and the diameter is also consistent.
[0044] In some embodiments, there are multiple second flow holes 133, each second flow hole 133 including multiple rows of radially distributed holes 135, each row of holes 135 including at least one second flow hole 133, and the multiple rows of holes 135 are uniformly radially distributed around the center of the heat insulation barrier plate 130; there are multiple fourth flow holes 171, and the multiple fourth flow holes 171 are configured to communicate with the multiple second flow holes 133 respectively.
[0045] Furthermore, the second flow hole 133 is a round hole, and the shape of the fourth flow hole 171 is adapted to the shape of the second flow hole 133.
[0046] It is worth noting that each row of holes 135 extends along the radial direction of the heat insulation baffle plate 130, and the included angle (i.e., the included angle of the extension direction) between adjacent rows of holes 135 is the same, and is θ. Preferably, each row of holes 135 can be distributed sequentially along the side extension direction of the first flow hole 131, which is easy to manufacture while ensuring the uniformity of the overall through hole distribution. The radius S of the distribution circle region of the second flow hole 133 is 100-150mm.
[0047] See Figures 2 to 7 In some embodiments, a first actuating rod 153 is provided on the edge of the first heat insulation plate 150, the first actuating rod 153 passes through the side wall of the crucible 110 and extends out of the crucible 110; a second actuating rod 173 is provided on the edge of the second heat insulation plate 170, the second actuating rod 173 passes through the side wall of the crucible 110 and extends out of the crucible 110. The first actuating rod 153 is integrally disposed on the edge of the first heat insulation plate 150 and extends radially along the first heat insulation plate 150, and the second actuating rod is integrally disposed on the outer edge of the second heat insulation plate 170 and extends radially along the second heat insulation plate 170. Both the first actuating rod 153 and the second actuating rod 173 extend out of the side wall of the crucible 110, enabling independent control of the rotation of the first heat insulation plate 150 and the second heat insulation plate 170, thus improving controllability.
[0048] Furthermore, a clearance hole 111 is provided through the side wall of the crucible 110. Both the first actuating rod 153 and the second actuating rod 173 pass through the clearance hole 111. A first shielding plate 155 is provided on the first actuating rod 153, and a second shielding plate 175 is provided on the second actuating rod 173. Both the first shielding plate 155 and the second shielding plate 175 are attached to the outer side wall of the crucible 110 and block the clearance hole 111. Specifically, the clearance hole 111 is opened on the side wall of the inner ring 115 of the crucible. The first shielding plate 155 and the second shielding plate 175 can always block the clearance hole 111, thereby preventing volatile components from leaking to the outside from the side and affecting crystal growth.
[0049] The first shielding plate 155 and the second shielding plate 175 are both arc-shaped, and the arc length is adapted to the outer wall of the inner ring 115 of the crucible. The central angle α corresponding to the arc length of the first shielding ring and the second shielding ring can be between 3θ and 5θ to ensure the shielding effect.
[0050] It should be noted that the first heat insulation plate 150 and the second heat insulation plate 170 are combined through the clearance hole 111 on the side wall of the crucible ring 115. By rotating the first heat insulation plate 150 and the second heat insulation plate 170 by a certain angle, different opening distributions can be obtained, thereby controlling the upward transport of gas components in different crystal growth stages.
[0051] This invention also provides a crystal growth method applicable to the aforementioned crystal growth apparatus 100, the crystal growth method comprising the following steps: S1: Place the powder into the powder placement area of crucible 110.
[0052] Specifically, silicon carbide powder can be placed into the crucible body 113 to complete the assembly of the crucible ring 115, growth ring 117 and seed crystal holder 190.
[0053] S2: Before crystal growth, rotate the first heat insulation plate 150 and the second heat insulation plate 170 so that the third flow hole 151 on the first heat insulation plate 150 is misaligned and closed with the first flow hole 131 on the heat insulation barrier plate 130, and the fourth flow hole 171 on the second heat insulation plate 170 is misaligned and closed with the second flow hole 133 on the heat insulation barrier plate 130.
[0054] Specifically, in the initial stage of crystal growth (i.e., the heating stage before actual crystal growth begins), to achieve controllability, the crystal growth initiation point can be artificially controlled. Simultaneously, to lower the temperature at the top seed crystal (i.e., the crystal growth zone temperature), the first heat insulation plate 150 and the second heat insulation plate 170 can be rotated to close the gaps between the three parts: the first heat insulation plate 150, the second heat insulation plate 170, and the heat insulation barrier plate 130. This separates the crystal growth zone and the powder placement zone into two parts: the bottom powder placement zone is the high-temperature zone, and the upper crystal growth zone is the low-temperature zone. With one edge of the clearance hole 111 set to 0 degrees, when the first heat insulation plate 150 and the second heat insulation plate 170 are positioned at nθ and 2mθ respectively (where n is an even number and m is an odd number), each hole is in a sealed state (i.e., a staggered closed state). For example, at this time, the first heat insulation plate 150 can be at 0°, and the second heat insulation plate 170 at 2θ.
[0055] In the initial stage of crystal growth, the temperature gradually increases, the furnace pressure gradually decreases, and the atmosphere concentration gradually increases. Since the initial control of crystal growth is unpredictable, the concentration and temperature control during the initial stage are also unpredictable, and their impact on crystal quality is uncontrollable. This structure closes the lower and upper atmosphere transport channels during the initial stage of crystal growth, eliminating uncontrollable factors.
[0056] S3: When crystal growth begins, rotate the first heat insulation plate 150 and the second heat insulation plate 170 again so that the third flow hole 151 is connected to the first flow hole 131 and the fourth flow hole 171 is connected to the second flow hole 133.
[0057] Specifically, when crystal growth begins, the first heat shield 150 and the second heat shield 170 are rotated at angles of nnθ (nn is an odd number) and 2mmθ (mm is an even number), respectively. This fully opens the upper and lower atmosphere transport channels. At the same time, the opening ratio of the transport channels can be controlled by changing the opening angle, thereby controlling the crystal growth speed.
[0058] S4: After the preset crystal growth time, rotate the second heat insulation plate 170 again to make the fourth flow hole 171 close in a misaligned manner with the second flow hole.
[0059] Specifically, during crystal growth, because the temperature at the edges is higher than in the center, the powder at the edges reacts preferentially. As the crystal growth time increases, the reaction of the powder at the edges becomes known as carbon-rich component. Continued participation of this carbon-rich component in the reaction can cause defects such as carbon inclusions in the silicon carbide crystal, severely affecting crystal quality. Therefore, in the later stages of crystal growth, the first heat insulation plate 150 and the second heat insulation plate 170 can be moved to nθ (n is an even number) and 2mmθ (mm is an even number), respectively, completely blocking the edge region while leaving the center region open. This prevents the carbon-rich component in the edge region from rising upwards, alleviating the carbon inclusion phenomenon.
[0060] In summary, the crystal growth apparatus 100 and crystal growth method provided in this embodiment of the invention include a heat insulation baffle plate 130 disposed in the middle of the crucible 110. The heat insulation baffle plate 130 has a first flow hole 131 in its central region and a second flow hole 133 in its edge region to achieve heat insulation. Simultaneously, a first heat insulation plate 150 and a second heat insulation plate 170 are disposed on the side of the heat insulation baffle plate 130 away from the powder placement area. The first heat insulation plate 150 and the second heat insulation plate 170 respectively cover at least the central region and the edge region of the heat insulation baffle plate 130, and are respectively provided with only a third flow hole 151 and a fourth flow hole. A seed crystal holder 190 is disposed on the top of the crucible 110 to support the seed crystal. During actual crystal growth, using the crystal growth apparatus 100, by rotating the first heat insulation plate 150 and the second heat insulation plate 170, the third flow hole 151 and the first flow hole 131 can be misaligned and closed before crystal growth, and the fourth flow hole 171 and the second flow hole 133 can be misaligned and closed. This allows the first heat insulation plate 150, the second heat insulation plate 170, and the heat insulation barrier plate 130 to form a heat insulation and sealing structure, blocking the sublimated gas in the powder placement area during the heating process, preventing defects and crystal form changes caused by the sublimated gas in the early stages of crystal growth. At the beginning of crystal growth, the third flow hole 151 can be connected to the first flow hole 131, and the fourth flow hole 171 can be connected to the second flow hole 133, fully opening the upper and lower atmosphere transport channels. In the middle and later stages of crystal growth, the fourth flow hole 171 and the second flow hole 133 can be misaligned and closed, hindering the upward transport of carbon-rich components in the edge region, alleviating defects caused by carbon inclusions, and improving crystal quality. Compared to existing technologies, the crystal growth apparatus 100 provided in this embodiment of the invention, through the arrangement of a first heat insulation plate 150, a second heat insulation plate 170, and a heat insulation barrier plate 130, and by coordinating rotation to determine whether each flow path is connected or not, can solve the problem of silicon and carbon component enrichment in the early and middle stages of crystal growth, effectively alleviating the carbon encapsulation problem. Furthermore, the first heat insulation plate 150, the second heat insulation plate 170, and the heat insulation barrier plate 130 can form a heat insulation and sealing structure, dividing the crucible 110 into a hot zone (powder placement zone) and a cold zone (crystal growth zone), alleviating the seed crystal sublimation problem, widening the process window, and facilitating the industrialization and promotion of silicon carbide crystals.
[0061] 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 technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A crystal growth apparatus, characterized in that, include: crucible; A heat insulation baffle is disposed in the middle of the crucible, dividing the crucible into a powder placement area and a crystal growth area. A first flow hole is provided in the central area of the heat insulation baffle, and a second flow hole is provided in the edge area of the heat insulation baffle. A first heat insulation plate is movably disposed on the side of the heat insulation barrier plate away from the powder placement area, and at least covers the central area of the heat insulation barrier plate, and a third flow hole is provided on the first heat insulation plate; The second heat insulation plate is movably disposed on the side of the heat insulation barrier plate away from the powder placement area, and at least covers the edge area of the heat insulation barrier plate, and the second heat insulation plate is provided with a fourth flow hole; A seed crystal holder is disposed on top of the crucible to support the seed crystal. Both the first heat insulation plate and the second heat insulation plate are rotatable relative to the heat insulation barrier plate, so that the third flow hole is selectively connected to the first flow hole, and / or the fourth flow hole is selectively connected to the second flow hole.
2. The crystal growth apparatus according to claim 1, characterized in that, The rotation axis of the first heat insulation plate and the rotation axis of the second heat insulation plate both pass through the center of the heat insulation barrier plate.
3. The crystal growth apparatus according to claim 1 or 2, characterized in that, The edge of the first heat insulation plate is provided with a first actuating rod, which passes through the side wall of the crucible and extends out of the crucible; The edge of the second heat insulation plate is provided with a second actuating rod, which passes through the side wall of the crucible and extends out of the crucible.
4. The crystal growth apparatus according to claim 3, characterized in that, The crucible has a clearance hole through its side wall. Both the first actuating rod and the second actuating rod pass through the clearance hole. The first actuating rod is provided with a first shielding plate, and the second actuating rod is provided with a second shielding plate. Both the first shielding plate and the second shielding plate are attached to the outer side wall of the crucible and block the clearance hole.
5. The crystal growth apparatus according to claim 1, characterized in that, There are multiple first flow holes, which are evenly distributed radially around the center of the heat insulation barrier plate; there are multiple third flow holes, which are configured to communicate with each of the multiple first flow holes respectively.
6. The crystal growth apparatus according to claim 5, characterized in that, Each of the first flow holes is triangular, and the apex angle of each first flow hole near the center of the heat insulation barrier is θ. The included angle formed by the sides of adjacent first flow holes is also θ. The shape of the third flow hole is adapted to the shape of the first flow hole.
7. The crystal growth apparatus according to claim 1, characterized in that, There are multiple second flow holes, each comprising multiple rows of radially distributed holes, each row of holes including at least one second flow hole, and the multiple rows of holes are evenly radially distributed around the center of the heat insulation barrier plate; there are multiple fourth flow holes, each configured to communicate with one of the multiple second flow holes respectively.
8. The crystal growth apparatus according to claim 7, characterized in that, The second flow hole is a round hole, and the shape of the fourth flow hole is adapted to the shape of the second flow hole.
9. The crystal growth apparatus according to claim 1, characterized in that, The crucible includes a crucible body, a crucible inner ring, and a growth ring. The crucible inner ring is detachably mounted on the crucible body, the growth ring is detachably mounted on the crucible inner ring, the seed crystal holder is mounted on the growth ring, and the heat insulation baffle is integrally mounted on the inner wall of the crucible inner ring.
10. A crystal growth method, characterized in that, The method, applicable to the crystal growth apparatus as described in claim 1, comprises: Place the powder into the powder placement area of the crucible; Before crystal growth, rotate the first heat insulation plate and the second heat insulation plate so that the third flow hole on the first heat insulation plate is misaligned and closed with the first flow hole on the heat insulation barrier plate, and the fourth flow hole on the second heat insulation plate is misaligned and closed with the second flow hole on the heat insulation barrier plate. When crystal growth begins, rotate the first heat insulation plate and the second heat insulation plate again so that the third flow hole is connected to the first flow hole and the fourth flow hole is connected to the second flow hole. After the crystal growth time is preset, the second heat insulation plate is rotated again to make the fourth flow hole close in a staggered manner with the second flow hole.