Efficient growth apparatus for producing high-quality silicon carbide single crystals

Abstract

This invention discloses an efficient apparatus for growing high-quality silicon carbide single crystals, comprising a first crucible, a second crucible, and a filter section. A seed crystal is vertically mounted in the first crucible, with its initial growth step end close to the top wall of the first crucible. The second crucible defines a raw material cavity, which is connected to the interior of the first crucible. The filter section defines a receiving cavity, within which an atmosphere regulating component is provided. The atmosphere regulating component includes a carbon framework and silicon particles, with the silicon particles embedded within the carbon framework. The filter section is installed at the gas outlet of the second crucible, shielding the gas outlet, which is located below the seed crystal. The raw material in the second crucible sublimates into gas, is filtered by the filter section, and then enters the first crucible. This invention can reduce the growth rate at the initial growth step end of the seed crystal during crystal growth and can simultaneously adjust the Si / C atomic ratio in the silicon carbide atmosphere, thereby reducing the probability of initial phase transitions and improving crystal quality.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a growth apparatus for efficiently preparing high-quality silicon carbide single crystals. Background Technology

[0002] Related technologies indicate that due to the relatively high coexistence temperature of existing 4H and 6H crystal forms, crystals are prone to phase transitions, especially the initial phase transition, which is one of the serious problems in the growth process of silicon carbide crystals. The causes of phase transitions in crystals are generally as follows: 1) Traditional parallel placement of seed crystals allows inherited dislocations to easily penetrate the crystal, leading to phase transitions. 2) Excessive crystal growth rate at the initial growth step end of the seed crystal: Crystal growth begins at the initial growth step (growth facet) end of the seed crystal. If the crystal growth rate at this end is too fast, it increases the probability of atomic misalignment, leading to an initial phase transition at the initial growth step end, thus reducing crystal quality compared to penetrating the entire crystal during the growth process. 3) The Si / C atomic ratio in the silicon carbide atmosphere also contributes to phase transitions during crystal growth. Since initial phase transitions mostly occur at the initial growth step end of the seed crystal, how to suppress the initial phase transition at the initial growth step end during the early stages of crystal growth is a pressing technical problem that needs to be solved. Summary of the Invention

[0003] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes an efficient apparatus for preparing high-quality silicon carbide single crystals. During crystal growth, this apparatus can reduce the growth rate at the initial growth step of the seed crystal and simultaneously adjust the Si / C atomic ratio in the silicon carbide atmosphere, thereby reducing the probability of early phase transitions and improving crystal quality.

[0004] This invention also proposes a high-efficiency growth apparatus for preparing high-quality silicon carbide single crystals, comprising a first crucible, a second crucible, and a filter section; a seed crystal is vertically installed in the first crucible, with the initial growth step end of the seed crystal close to the top wall of the first crucible; the second crucible defines a raw material cavity, which communicates with the interior of the first crucible; the filter section defines a receiving cavity, and an atmosphere regulating component is provided in the receiving cavity, the atmosphere regulating component comprising a carbon frame and silicon particles, the silicon particles being embedded inside the carbon frame; the filter section is installed at the gas outlet of the second crucible and forms a shield for the gas outlet of the second crucible, the gas outlet of the second crucible being located below the seed crystal, the raw material in the second crucible sublimating into gas is filtered by the filter section and then enters the first crucible.

[0005] In the above scheme, the seed crystal is installed vertically in the first crucible, and its initial growth step end is close to the top wall of the first crucible. Therefore, the initial growth step end of the seed crystal is located at the top. After the silicon carbide gas enters the first crucible, its concentration will gradually decrease during the rising process. Therefore, the gas concentration at the initial growth step end of the seed crystal is lower than the gas concentration in other parts of the seed crystal, which makes the crystal growth rate at the initial growth step end of the seed crystal lower than the growth rate in other parts of the seed crystal. This reduces the growth rate at the initial growth step end of the seed crystal. After the growth rate at this end is reduced, the stability of Si / C atomic stacking is better, that is, the arrangement is more stable, effectively reducing atomic "misalignment" and other situations, and better suppressing the occurrence of initial phase transition at the initial growth step end of the seed crystal, thereby reducing the probability of initial phase transition of the crystal as a whole and improving the quality of the crystal.

[0006] In addition, the atmosphere conditioning components inside the filter section can adjust the Si / C atomic ratio in the silicon carbide atmosphere, achieving selective compensation of the atmosphere in the early and late stages of crystal growth. This solves the technical problems of carbon encapsulation and silicon-rich in the early stage and carbon-rich in the later stage of crystal growth, further reducing the probability of initial phase transition in the crystal and improving the overall quality of the crystal.

[0007] In some embodiments, a first airflow channel is provided on the top wall of the first crucible of the present invention to accelerate the gas flow rate. The diameter of the first airflow channel is 3mm-5mm. In this embodiment, the first airflow channel achieves the purpose of rapidly dispersing silicon carbide gas in the first crucible, preventing excess gas from lingering at the initial growth step of the seed crystal due to slow diffusion and forming crystals. This further reduces the concentration of silicon carbide gas at the initial growth step of the seed crystal, reduces the growth rate of the crystal at that point, and thus further reduces the probability of an initial phase transition occurring at the initial growth step of the seed crystal, thereby reducing the probability of an initial phase transition occurring in the overall crystal and improving the overall quality of the crystal.

[0008] In some embodiments, the outer wall of the first crucible of the present invention is provided with a heat-insulating felt, and the heat-insulating felt on the top outer wall of the first crucible defines a second airflow channel. The second airflow channel communicates with the interior of the quartz cover through the first airflow channel. This embodiment provides a second airflow channel, which allows excess gas in the first crucible to quickly diffuse out of the first crucible through the first and second airflow channels, reducing the gas concentration at the initial growth step of the seed crystal, thereby reducing the probability of early phase transition in the crystal and improving crystal quality.

[0009] In some embodiments, the first crucible of the present invention includes a gas evacuation chamber and a growth chamber. The gas evacuation chamber is located above the growth chamber and communicates with it. The seed crystal is vertically installed inside the growth chamber. The first airflow channel is disposed on the top wall of the gas evacuation chamber. The volume of the gas evacuation chamber is larger than the volume of the growth chamber. The first crucible is connected above the second crucible, and the gas outlet of the second crucible is located on the upper part of the second crucible. The filter is installed at the gas outlet end of the second crucible and extends downward to the inner bottom of the second crucible. In this embodiment, the seed crystal is vertically installed inside the growth chamber, and the gas evacuation chamber is installed above the growth chamber. The purpose is to allow excess gas in the growth chamber to quickly diffuse into the gas evacuation chamber and then quickly diffuse to the outside of the first crucible through the first and second airflow channels. This further prevents excess gas from lingering and accumulating at the initial growth step of the seed crystal, avoiding an increase in gas concentration at the initial growth step of the seed crystal, thereby reducing the crystal growth rate at that end, effectively avoiding or reducing the probability of initial phase transition in the crystal, and improving the overall quality of the crystal.

[0010] In some embodiments, the seed crystal of the present invention is longitudinally mounted on the inner sidewall of the growth chamber, and the longitudinal cross-sectional area of ​​the inner sidewall of the growth chamber gradually decreases from top to bottom. In this embodiment, the inner sidewall of the growth chamber is thicker at the top and thinner at the bottom, and the initial growth step end of the seed crystal is close to the upper part of the inner sidewall of the growth chamber. Therefore, the temperature at this end is relatively higher than the temperature of other parts of the seed crystal, which further reduces the growth rate of the crystal at this end, thereby reducing the probability of the crystal undergoing an initial phase transition and improving the crystal quality.

[0011] In some embodiments, a first heating element is installed on the top wall of the gas evacuation chamber of the present invention, extending to the initial growth step end of the seed crystal; the first heating element is coaxially arranged with the first crucible, and there is a predetermined distance between the first heating element and the seed crystal. In this embodiment, the bottom end of the first heating element is located at the initial growth step end of the seed crystal. Therefore, the heat emitted by the first heating element will make the temperature at the initial growth step end of the seed crystal higher than the temperature of other parts of the seed crystal, thereby reducing the probability of early phase transition of the crystal and improving the quality of the crystal.

[0012] In some embodiments, the thickness of the insulating felt on the outer top wall of the first crucible of the present invention gradually decreases towards the edge of the top wall of the gas evacuation chamber, centered on the intersection of the extended axis of the first heating element and the top wall of the gas evacuation chamber. This arrangement aims to create a small temperature gradient in the lateral direction by making the area near the axis of the first heating element hotter and the area far from the axis of the first heating element colder. Since the area where the seed crystal is located is far from the axis of the first heating element, the lateral temperature gradient facilitates gas flow towards the seed crystal and deposition and crystallization on the crystal surface. This airflow direction promotes more stable atomic arrangement on the crystal surface, thereby reducing the probability of early phase transitions and improving crystal quality.

[0013] In some embodiments, a support member is installed on the top wall of the gas evacuation chamber of the present invention and extends into the interior of the growth chamber. The lower longitudinal section of the support member is inverted "V" shaped. In this embodiment, an inverted V-shaped support member is provided on the back of the seed crystal. The purpose is to construct a structure in which, in the vertical direction, the material used in the support member gradually decreases from the initial growth step end of the seed crystal downwards, thereby making the temperature at the initial growth step end of the seed crystal the highest, thus slowing down the growth rate at that point, further reducing the probability of initial phase transition at that end, thereby reducing the probability of initial phase transition in the crystal and improving the quality of the crystal.

[0014] In some embodiments, the present invention further includes a flow guide with an annular component connected thereto. The annular component extends upward to the bottom of the support and is connected to the bottom of the support. The diameter of the annular component is the same as the diameter of the support. The flow guide also defines a plurality of flow-guiding holes. In this embodiment, the flow guide avoids crystallization at the bottom of the support and allows the gas to rise vertically, increasing the gas rising rate and thus improving the overall crystal growth rate.

[0015] In some embodiments, a heat dissipation cavity is provided inside the insulating felt at the top outer side of the first crucible of the present invention. The heat dissipation cavity is coaxially arranged with the support member, and the bottom of the heat dissipation cavity is the top of the first crucible. The longitudinal cross-sectional area of ​​the heat dissipation cavity gradually increases from top to bottom. In this embodiment, the heat dissipation cavity can create a temperature gradient in the lateral direction, with a lower temperature at the location of the seed crystal and a higher temperature at locations farther from the seed crystal. This makes it easier for the gas to flow towards the seed crystal during its ascent and to deposit and crystallize on the crystal surface. Such an airflow direction is conducive to a more stable arrangement of atoms on the crystal surface, thereby reducing the probability of early phase transitions in the crystal and improving the quality of the crystal.

[0016] In some embodiments, the second crucible of the present invention is disposed inside the first crucible, and the gas outlet of the second crucible is opened on the side wall of the second crucible. The filter portion surrounds the outer side wall of the second crucible and closely adheres to the second crucible to shield the gas outlet. A second heating element is disposed inside the second crucible, and a heat-insulating felt is disposed on the top outer wall of the second crucible. The seed crystal is disposed on the side wall of the heat-insulating felt on the top outer wall of the second crucible. In this embodiment, the provision of the second heating element increases the temperature inside the raw material chamber, thereby ensuring the temperature at which the raw material sublimates into gas, and thus ensuring the rate and quality of crystal growth.

[0017] In some embodiments, a third heating element is disposed inside the insulating felt on the outer top wall of the second crucible of the present invention. The bottom of the third heating element is connected to the outer top wall of the second crucible, and its longitudinal cross-sectional area gradually decreases from top to bottom. This embodiment can make the temperature at the initial growth step end of the seed crystal higher than the temperature of other parts of the seed crystal, thereby reducing the growth rate at that end, reducing the probability of initial phase transformation at that end, and further reducing the probability of initial phase transformation of the crystal, thus improving the quality of the crystal.

[0018] In some embodiments, the insulating felt on the top outer side of the first crucible is provided with a gas diffusion cavity. The bottom of the gas diffusion cavity is the top wall of the first crucible. The gas diffusion cavity is coaxially arranged with the second crucible, and the cross-sectional area of ​​the gas diffusion cavity is larger than that of the second crucible. The height of the gas diffusion cavity is 90cm-100cm. In this embodiment, the gas diffusion cavity can quickly discharge excess gas from the growth chamber, avoiding excess gas from staying or accumulating at the initial growth step of the seed crystal, reducing the gas concentration at that end, thereby reducing the growth rate at that end, and further reducing the probability of the initial phase transition of the crystal, thus improving the quality of the crystal. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of an apparatus for efficiently preparing high-quality silicon carbide single crystals according to an embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of an apparatus for efficiently preparing high-quality silicon carbide single crystals according to an embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of an apparatus for efficiently preparing high-quality silicon carbide single crystals according to an embodiment of the present invention.

[0022] Figure label:

[0023] 100: Silicon carbide single crystal growth apparatus;

[0024] 10: First crucible; 11: Gas evacuation chamber; 111: First airflow channel; 112: First heating element; 113: Support; 12: Growth chamber;

[0025] 20: Second crucible; 21: Silicon carbide powder; 22: Gas outlet; 23: Second heating element;

[0026] 30: Seed crystal;

[0027] 40: Filter section; 41: Atmosphere conditioning component;

[0028] 50: Insulation felt; 51: Second airflow channel; 52: Third heating element; 53: Gas diffusion chamber;

[0029] 60: Induction coil;

[0030] 70: Quartz cover;

[0031] 80: Heat dissipation cavity. Detailed Implementation

[0032] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0033] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. Additionally, examples of various specific processes and materials are provided in this invention; however, those skilled in the art will recognize the applicability of other processes and / or the use of other materials.

[0034] The following is for reference. Figures 1-3 The invention describes an efficient silicon carbide single crystal growth apparatus 100 for preparing high-quality silicon carbide single crystals according to an embodiment of the invention. The apparatus includes a quartz cover 70 and an induction coil 60 surrounding the outside of the quartz cover 70. A growth crucible and a filter section 40 are installed inside the quartz cover 70. The growth crucible is made of graphite.

[0035] Example 1

[0036] Reference Figure 1As shown, the high-efficiency silicon carbide single crystal growth apparatus 100 according to an embodiment of the present invention includes a growth crucible comprising a first crucible 10 and a second crucible 20. A seed crystal 30 is longitudinally installed in the first crucible 20, with the initial growth step (growth facet) end of the seed crystal 30 close to the top wall of the first crucible 10. It can be understood that the initial growth step end of the seed crystal 30 is located at the upper part of the seed crystal 30. The second crucible 20 defines a raw material cavity for holding silicon carbide powder 21, and the interior of the first crucible 10 communicates with the raw material cavity. A filter section 40 defines a receiving cavity, which is densely packed with atmosphere regulating elements 41 for regulating the gas atmosphere inside the first crucible 10. The atmosphere regulating element 41 includes a carbon frame and silicon particles, with the silicon particles embedded inside the carbon frame. The carbon frame is a sealed structure and can be square, stacked within the receiving cavity. Of course, the carbon frame can also be other shapes, such as circular. In some embodiments, multiple carbon frames can also be integrally formed into a large carbon frame, making installation more convenient.

[0037] A filter section 40 is installed at the gas outlet 22 of the second crucible 20, and forms a shield for the gas outlet 22 of the second crucible 20. The gas outlet 22 of the second crucible 20 is located below the seed crystal 30. After the silicon carbide powder 21 in the second crucible 20 sublimates into gas, it is filtered by the filter section 40 and then enters the first crucible 10. For example, the filter section 40 can be a hollow cylinder made of a filter screen with a pore size of 300-500 micrometers and a porosity of 65%-75%. It is used to filter large particles or impurities in the gas to improve the growth quality of the crystal. At the same time, the atmosphere regulating component 41 inside the filter section 40 can adjust the Si / C atomic ratio in the silicon carbide atmosphere, realizing selective compensation of the crystal growth atmosphere in the early and late stages of crystal growth. This solves the technical problems of carbon encapsulation and silicon-rich in the early stage and carbon-rich in the later stage of crystal growth, further reducing the probability of the initial phase transition of the crystal and improving the overall quality of the crystal.

[0038] In this embodiment, the second crucible 20 contains silicon carbide powder 21. The filter section 40 blocks the gas outlet 22 of the second crucible 20, and the filter section 40 is densely packed with atmosphere regulating elements 41. During crystal growth, after silicon carbide is heated and sublimated into silicon carbide gas, it passes through the filter section 40 to filter out large particles or impurities (such as light, floating large-diameter carbon particles, carbon chips, carbon flakes, etc.) and enters the first crucible 10. When the gas passes upward through the seed crystal 30, it will be deposited and crystallized on the surface of the seed crystal 30. Since the gas diffuses upwards, its concentration decreases as it diffuses. Furthermore, because the seed crystal 30 is vertically positioned within the first crucible 10, and the growth step of the seed crystal 30 is close to the top of the first crucible 10 (i.e., located at the upper part of the seed crystal 30), the gas concentration at the lower part of the seed crystal 30 surface is higher than that at the initial growth step of the seed crystal 30. The gas concentration affects the crystal growth rate; the higher the gas concentration, the faster the crystal growth rate. Therefore, the crystal growth rate at the initial growth step of the seed crystal 30 (located at the upper part of the seed crystal 30) is lower than that at the lower and middle parts of the seed crystal 30. The slower crystal growth rate at the growth step of the seed crystal 30 effectively reduces the initial phase transition at the growth step, thereby reducing the probability of an initial phase transition during crystal growth and improving the overall quality of the crystal.

[0039] Furthermore, because silicon carbide powder decomposes into Si, SiC2, and Si2C gas phases when heated, due to the different melting points and saturated vapor pressures of the atmosphere substances, the silicon carbide gas phase generally forms a highly corrosive silicon-rich atmosphere during the early stages of crystal growth. Later, as Si atoms in the atmosphere are continuously consumed and released, and due to the localized carbonization of the silicon carbide powder 21, the crystal growth atmosphere gradually transforms into a carbon-rich phase. In this embodiment, the atmosphere regulating component 41, which has atmosphere adjustment and compensation functions, can filter out large particles or impurities floating in the volatile atmosphere and adjust the Si / C atomic ratio in the silicon carbide atmosphere. During the early stages of crystal growth, the airflow containing a highly corrosive Si atmosphere continuously scours the carbon framework inside the filter section 40. Some Si atoms are adsorbed onto the carbon framework, while some carbon atoms on the carbon framework are carried into the Si-rich airflow, thus adjusting the Si / C atomic ratio in the Si-rich atmosphere. As crystal growth progresses, the Si-rich atmosphere in the early stage continuously etches the carbon framework of the atmosphere regulating element 41. In the later stage of crystal growth, the carbon framework of the atmosphere regulating element 41 is partially or extensively etched. At this time, the silicon particles within the carbon framework are exposed, and the crystal growth atmosphere changes from Si-rich to C-rich. The exposed Si comes into contact with the C-rich atmosphere, which again plays a neutralizing role. Some C is adsorbed, and some Si participates in the C-rich atmosphere, thus regulating the Si / C atomic ratio in the C-rich atmosphere. This solves the technical problems of carbon encapsulation and silicon-rich in the early stage and carbon-rich in the later stage of crystal growth, achieving selective compensation of the crystal growth atmosphere in the early and later stages. This further reduces the probability of the crystal undergoing an initial phase transition and improves the overall quality of the crystal.

[0040] In other alternative embodiments, the top wall of the first crucible 10 of the present invention is provided with a first airflow channel 111 to accelerate the airflow velocity. The diameter of the first airflow channel 111 is 3mm-5mm, preferably 4mm. This embodiment accelerates the gas flow rate out of the first crucible 10, further preventing the gas from staying and accumulating at the initial growth step end of the seed crystal 30, reducing the crystal growth rate at the initial growth step end of the seed crystal 30, thereby reducing the probability of an initial phase transition occurring at the initial growth step end of the seed crystal 30, reducing the probability of an initial phase transition occurring in the crystal during crystal growth, and improving the crystal quality.

[0041] In other alternative embodiments, the outer wall of the first crucible 10 of the present invention is provided with a heat-insulating felt 50, and the heat-insulating felt 50 on the outer top wall of the first crucible 10 defines a second airflow channel 51. The first airflow channel 111 communicates with the interior of the quartz cover 70 through the second airflow channel 51. In this embodiment, the heat-insulating felt 50 is used to maintain the temperature of crystal growth inside the first crucible 10 at the required process temperature, and the second airflow channel 51 is connected to the first airflow channel 111 mainly for the diffusion of gas inside the first crucible 10.

[0042] In order to quickly disperse the silicon carbide gas entering the first crucible 10 and prevent the gas from staying and accumulating at the initial growth step of the seed crystal 30, in other optional embodiments, the first crucible 10 of the present invention includes a gas evacuation chamber 11 and a growth chamber 12 arranged coaxially. The gas evacuation chamber 11 is located above the growth chamber 12 and the gas evacuation chamber 11 and the growth chamber 12 are connected. The seed crystal 30 is installed longitudinally in the growth chamber 12. The first airflow channel 111 is located on the top wall of the gas evacuation chamber 11. The volume of the gas evacuation chamber 11 is larger than the volume of the growth chamber 12. For example, if the diameter of the growth chamber 12 is diameter d1 and the height is h1, then the diameter d2 and the height h2 of the gas evacuation chamber 11 can be: d2≥2*d1, h2≥h1. The first crucible 10 is connected above the second crucible 20. The gas outlet 22 of the second crucible 20 is located on the upper part of the second crucible 20 and communicates with the growth chamber 12. The filter section 40 is installed at the gas outlet 22 end of the second crucible 20 and extends downward to the inner bottom of the second crucible 20. In this embodiment, the volume of the gas evacuation chamber 11 is larger than that of the growth chamber 12, which helps to accelerate the diffusion of excess gas from the growth chamber 12 to the gas evacuation chamber 11 and avoids gas from staying and accumulating in the gas evacuation chamber 11. In addition, in this embodiment, the filter section 40 extends to the inner bottom of the second crucible 20, resulting in a larger filtration area and better filtration effect. During crystal growth, gas rises to the growth chamber 12 and deposits on the surface of the seed crystal 30, forming crystals. Excess gas continues to rise and enters the gas evacuation chamber 11. Due to the relatively large space of the gas evacuation chamber 11, the excess gas diffuses into the gas evacuation chamber 11 more quickly, further preventing the gas from lingering at the initial growth step of the seed crystal 30 and suppressing the crystal growth rate at that point. On the other hand, the first airflow channel 111 at the top of the gas evacuation chamber 11 has a large aperture, which facilitates the rapid diffusion of gas to the outside of the gas evacuation chamber 11 and prevents the gas from accumulating inside the gas evacuation chamber 11. This further suppresses the crystal growth rate at the initial growth step of the seed crystal 30, thereby reducing the probability of the initial phase transition at the initial growth step of the seed crystal 30 and improving the quality of the crystal.

[0043] In other alternative embodiments, the seed crystal 30 of the present invention is installed on the inner sidewall of the growth chamber 12, and the thickness of the sidewall of the growth chamber 12 gradually decreases in its longitudinal cross-sectional area from top to bottom; the outer sidewall of the second crucible 20 is provided with a heat-insulating felt 50 to ensure that the temperature in the raw material chamber can be stably maintained at the temperature required by the process for a long time. In this embodiment, the thickness of the sidewall of the growth chamber 12 gradually decreases from top to bottom. The growth chamber 12 in this embodiment is made of graphite, and the upper part of the sidewall of the growth chamber 12 is thicker and the lower part is thinner. Therefore, the temperature of the upper part of the sidewall of the growth chamber 12 is higher. Since the installation position of the initial growth step end of the seed crystal 30 is close to the upper part of the growth chamber 12, the crystal growth rate of the initial growth step end of the seed crystal 30 will be slower than the crystal growth rate of other parts of the surface of the seed crystal 30 (the higher the temperature, the slower the crystallization). Slower crystallization will reduce the probability of the initial phase transformation occurring at the initial growth step end of the seed crystal 30, thereby reducing the probability of the initial phase transformation occurring during the crystal growth process and improving the overall quality of the crystal.

[0044] In other alternative embodiments, a first heating element 112 may be installed on the top wall of the gas evacuation chamber 11 of the present invention, extending to the initial growth step end of the seed crystal 30. The first heating element 112 is coaxially arranged with the growth chamber 12, and there is a certain distance between the first heating element 112 and the seed crystal 30. It is understood that the amethyst 30 does not contact the first heating element 112. In this embodiment, since the end of the first heating element 112 is located at the initial growth step end of the seed crystal 30, the temperature at the initial growth step end of the seed crystal 30 is affected by the heat emitted by the second heating element 112. The temperature at this end is higher than the temperature of other parts of the seed crystal 30, thereby reducing the growth rate at the initial growth step end of the seed crystal 30, and thus reducing the probability of the initial phase transition of the crystal and improving the quality of the crystal.

[0045] In other optional embodiments, the thickness of the insulation felt 50 on the outer top wall of the first crucible 10 gradually decreases towards the edge of the top wall of the first crucible 10, centered on the intersection of the extended axis of the first heating element 112 and the top wall of the first crucible 10. It can be understood that the insulation felt 50 is thicker closer to the first heating element 112. Therefore, the area near the axis of the first heating element 112 dissipates heat quickly and has a lower temperature, while the area farther from the axis of the first heating element 112 dissipates heat slowly and has a higher temperature, thus forming a small temperature gradient in the lateral direction. Since the seed crystal 30 is located on the inner wall of the growth chamber 12 away from the axis of the first heating element 112, the area where the seed crystal 30 is located has a lower temperature in the lateral direction. During the gas rise, the lateral temperature gradient facilitates gas flow towards the lower-temperature seed crystal 30 (gas flow direction as shown in the image). Figure 1 As shown in the figure, the atoms are deposited and crystallized on the crystal surface. This airflow direction is conducive to the more stable arrangement of atoms on the crystal surface, reduces the probability of early phase transition of the crystal, and improves the quality of the crystal.

[0046] In this embodiment, the first crucible 10 and the second crucible 20 can be assembled together, and the assembly steps are as follows:

[0047] 1) First, place the silicon carbide powder 21 and the filter section 40 inside the second crucible 20, and then assemble the top wall of the second crucible 20 onto the side wall of the second crucible 20.

[0048] 2) After installing the seed crystal 30 on the side wall of the growth chamber 12 of the first crucible 10, the first crucible 10 is then installed on the second crucible 20 as a whole, and the assembly is completed.

[0049] Example 2

[0050] Reference Figure 2 As shown, this embodiment is largely the same as the previous one, with the same reference numerals used for the same components. The only difference is that:

[0051] In this embodiment, a support member 113 is installed on the top wall of the gas evacuation chamber 11 and extends into the growth chamber 12. The lower longitudinal section of the support member 113 is inverted "V" shaped, meaning that the center of the bottom of the support member 113 is higher than the edge. In this embodiment, the support member 113 is made of graphite, and the support member 113 on the back side of the initial growth step end of the seed crystal 30 is thicker, generating more heat, thereby reducing the growth rate at that end, thus reducing the probability of initial phase transition at that end and improving the quality of the crystal.

[0052] In other alternative embodiments, this embodiment further includes a flow guide with an annular component connected to it. The annular component extends upward to and connects with the bottom of the support 113. The diameter of the annular component is the same as the diameter of the support 113. The flow guide also defines multiple flow-guiding holes to guide the gas flow. The use of the annular component effectively prevents the gas from contacting the bottom of the support 113, avoiding the possibility of crystallization at the bottom of the support 113, preventing waste of raw materials, and saving production costs.

[0053] In other optional embodiments, a heat dissipation cavity 80 is provided inside the heat insulation felt 50 on the top outer side of the first crucible 10 in this embodiment. The heat dissipation cavity 80 is coaxially arranged with the support member 113, and the bottom of the heat dissipation cavity 80 is the top of the first crucible 10. The longitudinal cross-sectional area of ​​the heat dissipation cavity 80 gradually increases from top to bottom. Since the longitudinal cross-sectional area of ​​the heat dissipation cavity 80 gradually increases from top to bottom in this embodiment, the area near the axis of the support member 113 dissipates heat quickly and has a lower temperature, while the area far from the axis of the support member 113 dissipates heat slowly and has a higher temperature, thus forming a small temperature gradient in the lateral direction. Since the seed crystal 30 is set on the support member 113, the area where the seed crystal 30 is located has a lower temperature in the lateral direction. During the upward process of the airflow, under the influence of the lateral temperature gradient, the airflow is conducive to flowing towards the seed crystal 30 where the temperature is lower (gas flow direction is as follows). Figure 2 As shown in the figure, crystals are deposited and crystallized on the surface of seed crystal 30 to form crystals. This airflow direction is conducive to the more stable arrangement of atoms on the crystal surface, reduces the probability of early phase transition of the crystal, and improves the quality of the crystal.

[0054] In practice, after the silicon carbide powder 21 sublimates into silicon carbide gas, it is filtered by the filter section 40 and its internal atmosphere regulating component 41, and then guided into the growth chamber 12 through the guide holes on the guide component. During the ascent, under the influence of the lateral temperature gradient, the gas flow is directed towards the seed crystal 30, which has a lower temperature, and deposits on the seed crystal 30 for crystal growth. Due to the restriction of the annular component, after the gas exits from the guide component, it rises directly along the gap between the seed crystal 30 and the growth chamber 12, avoiding contact with the bottom of the support component 113, effectively avoiding the problem of crystallization at the bottom of the support component 113, and saving raw material costs.

[0055] Example 3

[0056] Reference Figure 3 As shown, the structures of the first crucible 10, the second crucible 20, and the filter section 40 in this embodiment are the same as those in Embodiments 1 and 2. The difference is that in this embodiment, the second crucible 20 is located inside the first crucible 10, and the filter section 40 is located inside the first crucible 10 and surrounds the side wall of the second crucible 20. The specific structure is as follows:

[0057] Reference Figure 3As shown, in this embodiment, the second crucible 20 is coaxially disposed within the first crucible 10. The gas outlet 22 of the second crucible 20 is located on its side wall. It can be understood that multiple gas outlets 22 on the side wall of the second crucible 20 can accelerate gas diffusion. The filter section 40 surrounds the outer side wall of the second crucible 20 and closely adheres to the outside of the second crucible 20, thus blocking the gas outlets 22. It can be understood that after passing through the gas outlets 22 of the second crucible 20, the gas is filtered by the filter section 40 before entering the first crucible 10. A second heating element 23 made of graphite is disposed inside the second crucible 20. The second heating element 23 and the second crucible 20 can be coaxially disposed. A heat-insulating felt 50 is disposed on the top outer wall of the second crucible 20, and the seed crystal 30 is disposed on the side wall of the heat-insulating felt 50 on the top outer outer wall of the second crucible 20. The second heating element 23 in this embodiment is designed to ensure that the temperature inside the raw material chamber can be stably maintained for a long time to meet the process requirements of crystal growth.

[0058] In other alternative embodiments, a third heating element 52 made of graphite can also be provided inside the heat insulation felt 50 at the top of the second crucible 20 in this embodiment. The bottom of the third heating element 52 is connected to the outer top wall of the second crucible 20, and its longitudinal cross-sectional area gradually decreases from top to bottom, so that the heat generation at the upper part of the third heating element 52 is greater than that at the lower part, thereby generating more heat on the back side of the initial growth step end of the seed crystal 30, which in turn makes the temperature at the initial growth step end of the seed crystal 30 higher, reducing the growth rate of the crystal at that end, thereby reducing the probability of the initial phase transition of the crystal and improving the quality of the crystal.

[0059] In other alternative embodiments, the insulation felt 50 on the top outer side of the first crucible 10 in this embodiment is provided with a gas diffusion cavity 53 coaxially arranged with the second crucible 20. The bottom of the gas diffusion cavity 53 is the top wall of the second crucible 20, the cross-sectional area of ​​the gas diffusion cavity 53 is larger than the cross-sectional area of ​​the second crucible 20, and the height of the gas diffusion cavity 53 is 90-100cm. In this embodiment, the gas diffusion cavity 53 has a large space, which is conducive to the rapid diffusion of excess gas in the first crucible 10 into the gas diffusion cavity 53 through the first airflow channel 111. This avoids excess gas from staying and accumulating at the initial growth step end of the seed crystal 30, further reducing the gas concentration at that end. This prevents the growth rate at the initial growth step end of the seed crystal 30 from being too fast, which could lead to an initial phase transition and improve the quality of the crystal.

[0060] Before starting the equipment, first place silicon carbide powder 21 in the second crucible 20, then install the seed crystal 30 on the side wall of the heat insulation felt 50 with the third heating element 52 inside, and finally install the heat insulation felt 50 with the seed crystal 30 installed on it as a whole at the bottom of the second crucible 20. During crystal growth, the heat emitted by the second heating element 23 inside the second crucible 20 ensures the heat required for the sublimation of silicon carbide powder 21. The setting of the third heating element 52 ensures that the temperature at the initial growth step end of the seed crystal 30 is higher than the temperature of other parts of the seed crystal 30. After the silicon carbide powder 21 sublimates into gas, it enters the first crucible 10 through the filter section 40 and the atmosphere conditioning element 41. During the upward process of the gas, it is deposited on the seed crystal 30 for crystal growth. Since the seed crystal 30 is vertically installed, the gas concentration decreases during the upward process. The gas concentration at the initial growth step end of the seed crystal 30 is lower than the concentration at other parts of the surface of the seed crystal 30. In addition, since the temperature at the initial growth step end of the seed crystal 30 is higher than the temperature of other parts of the seed crystal 30, the crystal growth rate at the initial growth step end of the seed crystal 30 is lower than the crystal growth rate at other parts of the seed crystal 30, thereby reducing the probability of initial phase transformation at the initial growth step end of the seed crystal 30 and improving the crystal growth quality. Because the gas is filtered out by the filter section 40 to remove large particles and impurities, the crystal quality is improved. At the same time, the atmosphere regulating component 41 inside the filter section 40 regulates the crystal growth atmosphere, which solves the technical problem of silicon-rich in the early stage and carbon-rich in the later stage of crystal growth. It achieves selective compensation of the crystal growth atmosphere in the early and later stages, further reduces the probability of the crystal undergoing an initial phase transition, and improves the overall quality of the crystal.

[0061] Other components of the efficient silicon carbide single crystal growth apparatus 100 according to embodiments of the present invention, such as the first crucible 10, the second crucible 20, the heat insulation felt 50, the induction coil 60, etc., and their operation are known to those skilled in the art and will not be described in detail here.

[0062] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used 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. Therefore, they should not be construed as limitations on this invention.

[0063] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0064] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0065] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0066] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0067] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A growth apparatus for efficiently preparing high-quality silicon carbide single crystals, characterized in that, include: A growth crucible, comprising a first crucible and a second crucible, wherein a seed crystal is longitudinally installed in the first crucible and the initial growth step end of the seed crystal is close to the top wall of the first crucible; the second crucible defines a raw material cavity, which communicates with the interior of the first crucible. The filter section defines a receiving cavity, and an atmosphere regulating component is provided inside the receiving cavity. The atmosphere regulating component includes a carbon frame and silicon particles, with the silicon particles embedded inside the carbon frame. The filter section is installed at the gas outlet of the second crucible and blocks the gas outlet of the second crucible. The gas outlet of the second crucible is located below the seed crystal. After the raw material in the second crucible sublimates into gas, it is filtered by the filter section and then enters the first crucible. The first crucible has a first airflow channel on its top wall to accelerate the gas flow rate; the first crucible includes a gas evacuation chamber and a growth chamber, the gas evacuation chamber is located above the growth chamber and is connected to the growth chamber, the seed crystal is vertically installed in the growth chamber, the first airflow channel is provided on the top wall of the gas evacuation chamber, and the volume of the gas evacuation chamber is larger than the volume of the growth chamber; the first crucible is connected above the second crucible, and the gas outlet of the second crucible is located on the upper part of the second crucible; the filter is installed at the gas outlet end of the second crucible and extends downward to the inner bottom of the second crucible.

2. The growth apparatus for efficiently preparing high-quality silicon carbide single crystals according to claim 1, characterized in that, The diameter of the first airflow channel is 3mm-5mm.

3. The growth apparatus for efficiently preparing high-quality silicon carbide single crystals according to claim 2, characterized in that, The outer wall of the first crucible is provided with a heat-insulating felt, and the heat-insulating felt on the top wall of the outer side of the first crucible defines a second airflow channel. The first airflow channel communicates with the inside of the quartz cover through the second airflow channel.

4. The growth apparatus for efficiently preparing high-quality silicon carbide single crystals according to claim 3, characterized in that, The seed crystal is longitudinally installed on the inner sidewall of the growth chamber, and the longitudinal cross-sectional area of ​​the inner sidewall of the growth chamber gradually decreases from top to bottom.

5. A growth apparatus for efficiently preparing high-quality silicon carbide single crystals according to claim 3 or 4, characterized in that, A first heating element is installed on the inner top wall of the gas evacuation chamber and extends to the initial growth step of the seed crystal; the first heating element is coaxially arranged with the growth chamber and there is a set distance between the first heating element and the seed crystal.

6. The growth apparatus for efficiently preparing high-quality silicon carbide single crystals according to claim 5, characterized in that, The thickness of the insulation felt on the outer top wall of the first crucible gradually decreases towards the edge of the top wall of the first crucible, with the intersection of the extended line of the first heating element's axis and the top wall of the first crucible as the center; the outer wall of the second crucible is provided with an insulation felt.

7. The growth apparatus for efficiently preparing high-quality silicon carbide single crystals according to claim 6, characterized in that, The top wall of the gas evacuation chamber is equipped with a support member that extends into the interior of the growth chamber. The lower longitudinal section of the support member is inverted "V" shape.

8. The growth apparatus for efficiently preparing high-quality silicon carbide single crystals according to claim 7, characterized in that, It also includes a flow guide, on which an annular component is connected. The annular component extends upward to the bottom of the support and is connected to the bottom of the support. The diameter of the annular component is the same as the diameter of the support. The flow guide also defines a plurality of flow guide holes.

9. The growth apparatus for efficiently preparing high-quality silicon carbide single crystals according to claim 8, characterized in that, A heat dissipation cavity is provided inside the heat insulation felt on the top outer side of the first crucible. The heat dissipation cavity is coaxially arranged with the support member. The bottom of the heat dissipation cavity is the top of the first crucible. The longitudinal cross-sectional area of ​​the heat dissipation cavity gradually increases from top to bottom.

10. The growth apparatus for efficiently preparing high-quality silicon carbide single crystals according to claim 1, characterized in that, The second crucible is coaxially disposed inside the first crucible. The gas outlet of the second crucible is opened on the side wall of the second crucible. The filter is surrounded on the outer side wall of the second crucible and closely attached to the side wall of the second crucible to block the gas outlet. A second heating element is disposed inside the second crucible. A heat insulation felt is disposed on the top outer wall of the second crucible. The seed crystal is disposed on the side wall of the heat insulation felt on the top outer wall of the second crucible.

11. The growth apparatus for efficiently preparing high-quality silicon carbide single crystals according to claim 10, characterized in that, A third heating element is provided inside the heat-insulating felt on the outer top wall of the second crucible. The bottom of the third heating element is connected to the outer top wall of the second crucible, and its longitudinal cross-sectional area gradually decreases from top to bottom.

12. The growth apparatus for efficiently preparing high-quality silicon carbide single crystals according to claim 11, characterized in that, The heat-insulating felt on the top outer side of the first crucible is provided with a gas diffusion cavity. The bottom of the gas diffusion cavity is the top wall of the first crucible. The gas diffusion cavity is coaxially arranged with the second crucible. The cross-sectional area of ​​the gas diffusion cavity is larger than the cross-sectional area of ​​the second crucible. The height of the gas diffusion cavity is 90cm-100cm.

Images