Crystal growth device

Abstract

Embodiments of the present application provide a crystal growth device. The device comprises a furnace body, a crucible, and a heating assembly, wherein the furnace body comprises a furnace chamber, and the crucible and the heating assembly are both arranged in the furnace chamber.

Description

A crystal growth apparatus TECHNICAL FIELD

[0001] The present specification relates to the field of crystal growth, and in particular, to a crystal growth apparatus. BACKGROUND

[0002] Physical Vapor Transport (PVT) is a method for preparing semiconductor crystals. In the process of growing semiconductor crystals, an axial temperature gradient is formed between a material and a seed crystal by controlling the temperature field distribution in a growth cavity (e.g., a crucible). The material is sublimated into a gas phase component under high temperature conditions, and the gas phase component is transported to the seed crystal at a low temperature zone under the driving of the axial temperature gradient, and is deposited on the surface of the seed crystal to form a crystal.

[0003] SUMMARY

[0004] One of the embodiments of the present specification provides a crystal growth apparatus, the apparatus comprising a furnace body, a crucible and a heating assembly; wherein the furnace body comprises a furnace chamber, the crucible and the heating assembly are both arranged in the furnace chamber; the heating assembly heats the crucible.

[0005] In some embodiments, the heating assembly comprises a first heating assembly and / or a second heating assembly, wherein the first heating assembly heats the bottom of the crucible; the second heating assembly heats the side of the crucible.

[0006] In some embodiments, the second heating assembly comprises the second induction coil; the second induction coil is arranged around the side wall of the crucible; the first heating assembly comprises a first induction coil, the first induction coil is arranged around the bottom wall of the crucible; or the first heating assembly comprises a first resistance heater, the first heating assembly is arranged below the bottom wall of the crucible.

[0007] In some embodiments, the bottom of the crucible is provided with a graphite ring, the first induction coil is at least partially outside the graphite ring; or the first resistance heater is embedded in the bottom wall of the crucible.

[0008] In some embodiments, an annular partition is arranged between the first induction coil and the second induction coil, the annular partition is arranged around the crucible.

[0009] In some embodiments, the heating assembly further comprises a third heating assembly, the third heating assembly heats the top of the crucible.

[0010] In some embodiments, the third heating assembly comprises a second resistance heater.

[0011] In some embodiments, the average distance between the first resistance heater and the second resistance heater and the crucible is greater than 20 mm; and / or, both the first resistance heater and the second resistance heater include resistance wires, and the minimum spacing between the resistance wires is in the range of 10 mm to 15 mm.

[0012] In some embodiments, during the crystal growth stage, the ratio of bottom heat to side heat obtained by the material in the crucible is 1-4, and the ratio of side heat to top heat is 1-3; during the annealing stage, the ratio of top heat to side heat obtained by the material in the crucible is in the range of 1.5-5, the bottom heat is provided by the first heating component, the side heat is provided by the second heating component, and the top heat is provided by the third heating component.

[0013] In some embodiments, the second heating component further includes a third induction coil, which is sleeved on the outside of the second induction coil.

[0014] In some embodiments, the power of the first induction coil is greater than the power of the second induction coil.

[0015] In some embodiments, the device further includes: a first induction coil moving mechanism for driving the second induction coil to move along the axial direction of the crucible, the first induction coil moving mechanism being connected to the second induction coil; and a second induction coil moving mechanism for driving the third induction coil to move along the axial direction of the crucible, the second induction coil driving mechanism being connected to the third induction coil.

[0016] In some embodiments, the device further includes a fourth induction coil and a fifth induction coil, the fourth induction coil being disposed below the second induction coil in the axial direction of the crucible; the fifth induction coil being sleeved outside the fourth induction coil, and the fifth induction coil being disposed below the third induction coil in the axial direction of the crucible.

[0017] In some embodiments, the device further includes a filter structure disposed within the furnace chamber, the filter structure being located above the material in the crucible in the axial direction of the crucible, wherein the filter structure includes a through hole extending from top to bottom along the axial direction of the crucible.

[0018] In some embodiments, the material of the filter structure includes graphite; or the material of the filter structure includes one or more of tantalum, tungsten, titanium, and corresponding nitrides or carbides.

[0019] In some embodiments, the through holes in the middle of the filter structure have larger pore sizes and lower porosity, while the through holes in the edge portion of the filter structure have smaller pore sizes and higher porosity.

[0020] In some embodiments, the porosity of the filter structure is in the range of 5% to 40%.

[0021] In some embodiments, the furnace includes multiple chambers, and there are multiple crucibles, each of which is disposed in one of the multiple chambers; the crystal growth apparatus further includes a conveying mechanism, at least a portion of which is located within the furnace, the multiple chambers are arranged along the conveying direction of the conveying mechanism, and the conveying mechanism conveys the multiple crucibles so that the multiple crucibles can move between different chambers.

[0022] In some embodiments, the number of chambers is at least three; the crystal growth process includes a preheating stage, a crystal growth stage, and an annealing stage; at least some of the chambers have a temperature range corresponding to the temperature range of the preheating stage, forming a first chamber; at least some of the chambers have a temperature range corresponding to the temperature range of the crystal growth stage, forming a second chamber; and at least some of the chambers have a temperature range corresponding to the temperature range of the annealing stage, forming a third chamber; the first chamber, the second chamber, and the third chamber are arranged along the conveying direction.

[0023] In some embodiments, a passage and an openable partition are provided between two adjacent chambers.

[0024] In some embodiments, the heating assembly includes a plurality of sixth induction coils and a plurality of coil lifting devices. The plurality of sixth induction coils and the plurality of coil lifting devices are respectively disposed in the plurality of chambers. The plurality of coil lifting devices are connected to the plurality of sixth induction coils in a one-to-one correspondence. The coil lifting devices are capable of lifting the sixth induction coils along the axial direction of the crucible.

[0025] In some embodiments, the device further includes a plurality of heat-insulating structures, which are disposed one-to-one on the outside of a plurality of crucibles; the heat-insulating structure includes a side heat-insulating part and a top heat-insulating part, and the top heat-insulating part is provided with a temperature measuring port.

[0026] In some embodiments, the crystal growth apparatus includes a first temperature measuring component, which includes a first electrical rail and a plurality of first thermometers. The plurality of first thermometers respectively measure the temperature in the inner cavity of the plurality of crucibles. The first electrical rail is disposed outside the crucibles, and the portion of each of the plurality of first thermometers extending out of the crucibles is in sliding electrical contact with the first electrical rail. The first electrical rail is parallel to the conveying direction of the conveying mechanism.

[0027] In some embodiments, the crystal growth apparatus further includes a plurality of third resistance heaters, which are respectively disposed in the plurality of chambers and located at the bottom of the plurality of crucibles, and the plurality of third resistance heaters are disposed below the conveying mechanism in the axial direction of the crucibles.

[0028] In some embodiments, the device further includes a material preparation component, which includes a tunnel furnace and a plurality of raw material furnaces; the tunnel furnace includes a heating chamber and a motion drive mechanism, the plurality of raw material furnaces are sequentially arranged in the heating chamber along the length direction of the tunnel furnace, and the motion drive mechanism drives the plurality of raw material furnaces to move along the length direction of the tunnel furnace; a fourth heating component is provided in the heating chamber, the fourth heating component being used to heat the raw material furnaces.

[0029] In some embodiments, the tunnel furnace further includes an insulation layer that insulates the heating chamber.

[0030] In some embodiments, the tunnel furnace further includes a cooling mechanism located outside the heating chamber.

[0031] In some embodiments, the heating chamber includes a preheating section, a heating section and a cooling section in sequence along the length of the tunnel furnace, and each of the preheating section, the heating section and the cooling section is provided with a first temperature measuring mechanism and a first pressure measuring mechanism.

[0032] In some embodiments, the tunnel furnace includes a second temperature sensing component capable of measuring the temperature inside each of the raw material furnaces.

[0033] In some embodiments, the second temperature measuring component includes a second electrical rail and a plurality of second thermometers, the plurality of second thermometers measuring the temperature inside a plurality of the raw material furnaces respectively, the second electrical rail being disposed outside the raw material furnaces, and the portion of each of the plurality of second thermometers extending out of the raw material furnaces making sliding electrical contact with the second electrical rail, the second electrical rail being parallel to the length direction of the tunnel furnace.

[0034] In some embodiments, the plurality of raw material furnaces are connected in sequence, and the motion drive mechanism includes a push rod or a pull rod, the push rod or the pull rod being connected to one of the plurality of raw material furnaces.

[0035] In some embodiments, the device further includes at least one of a mixing chamber, a compaction chamber, and a pre-vacuum chamber.

[0036] In some embodiments, the mixing chamber includes a pressure relief device and / or a weighing device.

[0037] In some embodiments, the raw material furnace includes a raw material furnace body and a top cover, the top cover being provided with a seed crystal bonding surface.

[0038] In some embodiments, there are multiple fourth heating components, which are arranged around the multiple raw material furnaces respectively, and each raw material furnace is provided with a second temperature measuring mechanism and a second pressure measuring mechanism.

[0039] One embodiment of this specification provides a crystal growth method using the crystal growth equipment described above. The crystal growth process includes a crystal growth stage and an annealing stage. The method includes: in the crystal growth stage, heating the crucible using a first heating component and a second heating component; and in the annealing stage, heating using a second heating component and a third heating component. Attached Figure Description

[0040] This specification will be further described by way of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting; in these embodiments, the same reference numerals denote the same structures, wherein:

[0041] Figure 1 is a block diagram of a crystal growth apparatus according to some embodiments of this specification;

[0042] Figure 2 is a schematic diagram of the structure of a crystal growth apparatus according to some embodiments of this specification;

[0043] Figure 3 is a schematic diagram of the structure of a resistance heater according to some embodiments of this specification;

[0044] Figure 4 is a schematic diagram of the arrangement of the first induction coil according to some embodiments of this specification;

[0045] Figure 5 is a schematic diagram of the arrangement of the first induction coil and the second induction coil according to some embodiments of this specification;

[0046] Figure 6A is a schematic diagram of the structure of the second heating assembly according to some embodiments of this specification;

[0047] Figure 6B is a schematic diagram of the structure of the second heating component and the first induction coil moving mechanism according to some embodiments of this specification;

[0048] Figure 7 shows the axial temperature gradient of the crucible's inner cavity at different positions.

[0049] Figure 8 shows the axial temperature distribution inside the crucible at different positions.

[0050] Figure 9 shows the axial temperature distribution inside the crucible corresponding to different power levels of the third induction coil.

[0051] Figure 10 is a bar chart showing the temperature difference between the seed crystal and the material surface corresponding to different power levels of the third induction coil.

[0052] Figure 11A is a schematic diagram of the structure of a second heating assembly according to some other embodiments of this specification;

[0053] Figure 11B shows the axial temperature distribution inside the crucible for the fourth and fifth induction coils at different power levels.

[0054] Figure 11C is a bar graph showing the temperature difference between the seed crystal and the material surface under different power conditions for the fourth and fifth induction coils;

[0055] Figure 12 is a schematic diagram of a crystal growth apparatus according to some other embodiments of this specification;

[0056] Figure 13 is a schematic diagram of the crystal growth apparatus according to some embodiments of this specification;

[0057] Figure 14 is a schematic diagram of a filter structure according to some embodiments of this specification;

[0058] Figure 15A is a schematic diagram of the structure of a crystal growth apparatus according to some embodiments of this specification;

[0059] Figure 15B is a schematic diagram of the structure of a crystal growth apparatus according to some embodiments of this specification;

[0060] Figure 16 is a schematic diagram of the structure of a material preparation assembly according to some embodiments of this specification;

[0061] Figure 17 is a schematic diagram of the structure of a raw material furnace according to some embodiments of this specification.

[0062] Explanation of reference numerals in the attached drawings: 100, Crystal growth equipment; 110, Furnace body; 111, First chamber; 112, Second chamber; 113, Third chamber; 114, Partition; 120, Crucible; 130, Heating assembly; 121, Top cover; 122, Main body; 131, First heating assembly; 1311, First resistance heater; 13111, Resistance wire; 1312, First induction coil; 132, Second heating assembly; 1321, Second induction coil; 1322, Third induction coil; 1323, Fourth induction coil; 1324, Fifth induction coil; 133, Graphite ring; 134, Annular partition; 135, Third heating assembly; 1351, Second resistance heater; 136, Third resistance heater; 137, Sixth induction coil; 140, Material; 150, Filter structure; 151 160. Through hole; 161. Insulation structure; 162. Top insulation section; 163. Side insulation section; 170. Temperature measuring port; 180. Conveying mechanism; 181. First temperature measuring component; 182. First electric conductive rail; 190. First thermometer; 191. Material preparation component; 191. Tunnel furnace; 1911. Heating chamber; 19111. Preheating section; 19112. Heating section; 19113. Cooling section; 19 12. Motion drive mechanism; 19121. Push rod; 1913. Insulation layer; 1914. Compaction chamber; 1915. Pre-vacuum chamber; 1916. Mixing chamber; 192. Raw material furnace; 1921. Raw material furnace body; 1922. Top cover; 1923. Seed crystal bonding surface; 1924. Fourth heating component; 60. First induction coil moving mechanism; 61. Hanging rod; 62. Drive component; 200. Seed crystal. Detailed Implementation

[0063] To more clearly illustrate the technical solutions of the embodiments in this specification, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this specification. For those skilled in the art, these drawings can be applied to other similar scenarios without creative effort. Unless obvious from the context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0064] As indicated in this specification and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" are not specifically singular and may include plural forms. Generally, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements. The term "based on" means "at least partially based on." The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment."

[0065] It should be understood that the terms “system,” “device,” “unit,” and / or “module” used herein are one way to distinguish different components, elements, parts, sections, or assemblies at different levels. However, if other terms can achieve the same purpose, they may be replaced by other expressions.

[0066] The terms "first," "second," and similar terms used in this application and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms "an" or "a" and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. In the description of this specification, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly specified.

[0067] Unless otherwise stated, terms such as "top," "bottom," "side," "lower," and / or "upper" are for illustrative purposes only and are not intended to limit a location or spatial orientation. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0068] Flowcharts are used in this specification to illustrate the operations performed by the system according to embodiments of this specification. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, the steps can be processed in reverse order or simultaneously. Furthermore, other operations can be added to these processes, or one or more steps can be removed from them.

[0069] Figure 1 is a block diagram of a crystal growth apparatus according to some embodiments of this specification. As shown in Figure 1, the crystal growth apparatus 100 includes a furnace body 110, a crucible 120, and a heating assembly 130. The heating assembly 130 heats the crucible 120.

[0070] The crystal growth apparatus 100 can be used to prepare crystals. In some embodiments, the crystal growth apparatus 100 can prepare crystals based on the physical vapor transport (PVT) method. In some embodiments, the crystals may include, but are not limited to, silicon carbide crystals, aluminum nitride crystals, zinc oxide crystals, or zinc antimonide crystals.

[0071] The furnace body 110 is a structure for accommodating the crucible 120 and the heating assembly 130. In some embodiments, the furnace body 110 includes a furnace chamber, in which both the crucible 120 and the heating assembly 130 are disposed.

[0072] The crucible 120 is used to provide a site for crystal growth. In some embodiments, the crucible 120 includes an inner cavity and a wall surrounding the inner cavity, and material 140 is contained within the inner cavity of the crucible 120. In some embodiments, the material of the crucible 120 may include, but is not limited to, graphite. In some embodiments, the material of the crucible 120 may include graphite and silicon carbide. In some embodiments, the percentage of graphite by mass of the crucible 120 may be one of 40%–90%, 45%–85%, 50%–80%, 55%–75%, 60%–70%, 64%–66%, etc. In some embodiments, the shape of the crucible 120 may include, but is not limited to, a regular shape such as a cylinder or a cuboid, or an irregular shape. For ease of explanation, the crucible 120 is described as a cylinder, having an axial direction extending along its central axis. In the axial direction, the crucible 120 has two ends, one end being a top and the opposite end being a bottom, with the portion between the top and the bottom being a side portion.

[0073] In some embodiments, the crucible 120 may include a top cover 121 and a body 122. The body 122 may include the wall that surrounds the cavity forming an inner cavity, as described above, within the body 122. The top cover 121 may be located on top of the body 122 to close the top opening of the body 122.

[0074] In some embodiments, the shape of the main body 122 may include, but is not limited to, a cylinder, a cuboid, or a cube. In some embodiments, the shape of the upper cover 121 may include, but is not limited to, a disc, a rectangular disc, or a square disc. In some embodiments, the shapes of the upper cover 121 and the main body 122 may match. In some embodiments, the shape of the main body 122 may be cylindrical, including a bottom and sidewalls, the bottom forming the bottom wall of the crucible, and the sidewalls forming the sidewalls of the crucible. In some embodiments, the shape of the main body 122 may be a cylindrical body, and the shape of the upper cover 121 may be a disc. In some embodiments, the shape of the main body 122 may be a cuboid cylinder, and the shape of the upper cover 121 may be a rectangular disc or a square disc. In some embodiments, the materials of the upper cover 121 and the main body 122 may be the same or different.

[0075] In some embodiments, a seed crystal 200 is disposed above the crucible 120, and material 140 is disposed inside the crucible 120. In some embodiments, the seed crystal 200 may be adhered to the upper cover 121. The seed crystal 200 may be a small crystal with the same crystal orientation as the crystal to be grown, which can serve as a seed for crystal growth. In some embodiments, the seed crystal 200 may be prepared by physical vapor transport (PVT), chemical vapor deposition (CVD), or Czochralski method. In some embodiments, the size of the seed crystal 200 may be 4 inches, 8 inches, etc. The type of seed crystal 200 may be 4H-SiC seed crystal, 6H-SiC seed crystal, etc.

[0076] Material 140 is a raw material used for growing crystals. The raw material may include materials used to feed seed crystals to grow into crystals. In some embodiments, the composition of the raw material for silicon carbide crystals may include SiC. In some embodiments, the composition of the raw material for aluminum nitride crystals may include AlN. In some embodiments, the raw material may be in powder, granular, and / or bulk form.

[0077] As shown in Figure 2, a seed crystal 200 can be bonded to the lower side of the upper cover 121, and material 140 can be placed inside the main body 122. In Figure 2, dashed line a shows the lower surface of the seed crystal 200, and dashed line b shows the upper surface of the material 140. The space between dashed lines a and b is the space for crystal growth.

[0078] During the crystal growth stage, the material 140 in the crucible 120 is heated and sublimated into a gaseous component. The gaseous component is transported to the seed crystal 200 in the crystallization region and then crystallizes on the surface of the seed crystal 200 to generate a crystal.

[0079] In some embodiments, at least one temperature measuring component (not shown in FIG2) may also be provided inside the crucible 120. The temperature measuring component is used to measure the temperature inside the crucible 120. By way of example only, the temperature measuring component may include a temperature sensor, an infrared thermometer, etc.

[0080] In some embodiments, at least one temperature measuring component can be used to measure the temperature inside the crucible 120. For example, at least one temperature measuring component can be used to measure the temperature at at least one location, such as the lower surface of the seed crystal 200, the crystal growth surface, the upper surface of the material 140, or the space where the crystal grows.

[0081] The heating component 130 is used to heat the crucible 120 and provide the temperature field required for crystal growth. In some embodiments, when the heating component 130 heats the crucible 120, a temperature field can be formed inside the crucible 120 (i.e., in the inner cavity) to heat the material 140, causing the material 140 to sublimate, so as to grow a crystal on the growth surface of the seed crystal 200.

[0082] In some embodiments, the heating component 130 may include, but is not limited to, an electromagnetic induction heater, a resistance heater, etc. In some embodiments, the electromagnetic induction heater may include an induction coil. Under the action of alternating current at different frequencies, the induction coil can generate eddy currents on the outer wall of the crucible 120. Under the action of eddy currents, the electrical energy generated on the outer wall of the crucible 120 can be converted into heat energy, which is conducted from the wall of the crucible 120 to the interior of the crucible 120 to form a temperature field inside the crucible 120. In some embodiments, the resistance heater may include a resistance wire, the material of which may include, but is not limited to, at least one of graphite, tungsten, platinum, molybdenum, tantalum, or iridium. Accordingly, the resistance heater may include, but is not limited to, at least one of graphite resistance heaters, tungsten resistance heaters, platinum resistance heaters, molybdenum resistance heaters, tantalum resistance heaters, or iridium resistance heaters.

[0083] In some embodiments, when the heating assembly 130 is an electromagnetic induction heater, the electromagnetic induction heater may be arranged around the crucible 120. In some embodiments, the electromagnetic induction heater may be disposed in an external region of the crucible 120 at a certain distance from the outer wall of the crucible 120. In some embodiments, when the heating assembly 130 is a resistance heater, the resistance heater may be disposed on the crucible wall (such as the bottom wall or side wall) of the crucible 120. For example, it may be embedded in the crucible wall of the crucible 120 or connected to the outer surface of the crucible wall of the crucible 120. In other embodiments, when the heating assembly 130 is a resistance heater, the resistance heater may be disposed at a certain distance from the crucible wall (such as the bottom wall or side wall) of the crucible 120.

[0084] Heating the crucible 120 by the heating component 130 creates a temperature gradient within the crucible 120 (inner cavity). This temperature gradient can include axial and radial temperature gradients. An axial temperature gradient refers to the temperature difference per unit distance along the central axis of the inner cavity of the crucible 120. During crystal growth, a decreasing temperature along the central axis from the bottom to the top of the inner cavity creates an axial temperature gradient, which drives the sublimated gaseous components of the material 140 to be transported to the crystal growth surface. A radial temperature gradient refers to the temperature difference per unit distance along a horizontal cross-section at the same height within the inner cavity, from the inner wall of the crucible 120 to its central axis. During crystal growth, since the heating component 130 typically heats the crucible 120 from the outside, a decreasing radial temperature gradient occurs from the inner wall of the crucible 120 to its central axis.

[0085] In some embodiments, the heating component 130 may be disposed at the bottom of the crucible 120 (hereinafter referred to as the bottom). In this case, heat energy is conducted from the bottom region (the internal region near the bottom) inside the crucible 120 to the top region (the internal region near the top) inside the crucible 120. The bottom region inside the crucible 120 may be a relatively high-temperature region, and the top region may be a relatively low-temperature region, resulting in a monotonically decreasing axial temperature gradient inside the crucible 120 from bottom to top. In some embodiments, the heating component 130 may be disposed on the side of the crucible 120 (hereinafter referred to as the side). In this case, heat energy is conducted via the crucible 120 wall from the outer peripheral region (the region near the side of the crucible 120) inside the crucible 120 to the central region (the region near the central axis of the crucible 120) inside the crucible 120. The outer peripheral region inside the crucible 120 may be a relatively high-temperature region, and the central region may be a relatively low-temperature region. The temperature of the outer peripheral region is higher than the temperature of the central region, resulting in a radial temperature gradient inside the crucible 120. In some embodiments, the heating component 130 may be disposed at the top of the crucible 120 (hereinafter referred to as the top). In this case, similar to the heating component 130 being disposed at the bottom of the crucible 120, the placement of the heating component 130 at the top of the crucible 120 causes the axial temperature gradient inside the crucible 120 to decrease monotonically from top to bottom. It should be noted that the descriptions of the axial and radial temperature gradients inside the crucible 120 above refer to the temperature gradient cases where the heating component 130 is disposed only at the corresponding location (e.g., only at the bottom of the crucible 120, only on the side of the crucible 120, or only at the top of the crucible 120). It is understood that the heating component 130 may also be disposed at multiple locations (e.g., on the side and bottom of the crucible 120), which would result in a more complex temperature gradient situation inside the crucible 120. For example, the heating element 130 can be disposed at the bottom and top of the crucible 120. The crucible 120 may have a higher temperature at the top and bottom, while the temperature in the middle region between the top and bottom is lower. It should be noted that when the heating element 130 is disposed at the bottom of the crucible 120, it can be understood that the heating element 130 mainly heats the bottom of the crucible 120; when the heating element 130 is disposed at the side of the crucible 120, it can be understood that the heating element 130 mainly heats the side of the crucible 120; and when the heating element 130 is disposed at the top of the crucible 120, it can be understood that the heating element 130 mainly heats the top of the crucible 120.

[0086] In some embodiments, by adjusting the position of the heating component 130, the temperature distribution inside the crucible 120 can be adjusted, promoting crystal growth within the crucible 120 and ensuring crystal quality. In some embodiments, the heating component 130 can be disposed at the bottom and sides of the crucible 120. In some embodiments, the heating component 130 can be disposed at the bottom and top of the crucible 120. In some embodiments, the heating component 130 can be disposed at the sides and top of the crucible 120. In some embodiments, the heating component 130 can be disposed at the bottom, sides, and top of the crucible 120. The crystal growth apparatus 100 and the arrangement of its heating component 130 will be further described below with reference to Figures 2-13.

[0087] The following describes a method for preparing silicon carbide single crystals using a crystal growth apparatus 100, taking the preparation of silicon carbide single crystals as an example. This method may include the following steps:

[0088] Step 1: After placing the seed crystal 200 and the material 140 into the crucible 120, perform at least one of the following treatments on the crucible: vacuuming, leak detection, pressure holding, and furnace cleaning.

[0089] Step 1 can be seen as the operation required in the preparatory stage of the crystal growth process.

[0090] In some embodiments, the seed crystal 200 can be bonded to the inner side of the top cover 121, and the material 140 can be placed into the main body 122, with the top cover 121 bonded with the seed crystal placed on top of the main body 122. The seed crystal 200 can be bonded to the inner side of the top cover 121 using an adhesive. The adhesive can include, but is not limited to, epoxy resin glue, AB glue, phenolic resin glue, or sugar glue. Preferably, the adhesive can be sucrose with a purity of 99.9%. During the process of bonding and fixing the seed crystal, uneven application of the adhesive or poor processing precision of the inner side of the top cover may cause air bubbles or voids to form between the back of the seed crystal and the inner side of the top cover 121, resulting in defects in the generated crystal. Therefore, when placing the seed crystal at the exact center of the inner side of the top cover 121, it is necessary to avoid the formation of air bubbles or voids. In some embodiments, the seed crystal can be cleaned before bonding it to the inner side of the top cover to remove contaminants from its surface. In some embodiments, the seed crystal can be cleaned with deionized water, organic solvents, etc.

[0091] In some embodiments, material 140 (e.g., silicon carbide powder or lump) can be placed in the body 122, such that the distance between the upper surface of material 140 and the lower surface of seed crystal 200 is one of the following: 30mm-50mm, 35mm-50mm, 40mm-50mm, 45mm-50mm, 30mm-45mm, 35mm-45mm, 35mm-40mm, 30mm-40mm, 35mm-40mm, 30mm-35mm, 40mm-45mm, etc. In some embodiments, the distance between the upper surface of material 140 and the lower surface of seed crystal 200 can be one of 30mm, 35mm, 40mm, 45mm, 50mm, etc. In some embodiments, the surface of material 140 placed in the body 122 needs to be kept flat.

[0092] After the material 140 is placed into the main body 122, the top cover 121 with the seed crystal attached can be placed on top of the main body 122 to form a sealed space, which is conducive to the growth of the crystal.

[0093] In some embodiments, the filled and sealed crucible 120 can be placed in a temperature field for sealing, vacuuming, and leak detection, and then step 2 can be performed. For example, vacuuming can bring the pressure in the crucible 120 to 10⁻⁵ Pa. The vacuuming time can be 3 to 5 hours. After vacuuming, leak detection and pressure maintenance are required for 1 to 2 hours. Step 2 can begin when the leakage rate does not exceed 1 Pa within 1 hour.

[0094] Step 2: Adjust the pressure inside the crucible 120 by controlling the amount of gas introduced into the crucible 120, and adjust the temperature inside the crucible 120 by adjusting the heating component 130, so as to carry out crystal growth.

[0095] In some embodiments, after the preparatory stage (such as step 1) is completed, a sealed space is formed inside the crucible 120, at which point step 2 can begin. Step 2 can be considered as an operation required during crystal growth. The crystal growth process may include a preheating stage, a crystal growth stage, and an annealing stage. The preheating stage refers to heating the crucible 120 under high pressure until the temperature inside the crucible 120 reaches the temperature at which the material can stably sublimate. During the preheating stage, the pressure inside the crucible 120 is relatively high (e.g., maintained at 40 kPa-80 kPa). The temperature inside the crucible 120 increases (either continuously or in stages). The crystal growth stage refers to the stage where the material sublimates, thereby achieving continuous crystal growth on the seed crystal 200. During the crystal growth stage, the pressure inside the crucible 120 decreases significantly compared to the preheating stage (e.g., maintained at 1 kPa-1.2 kPa), and the temperature inside the crucible 120 may fluctuate slightly (e.g., increase by 100°C-300°C), but the overall temperature inside the crucible 120 remains within a relatively stable range (e.g., above 2000°C; see the relevant explanation of the temperature during the crystal growth stage below for details). The annealing stage refers to the stage where crystal growth almost ceases, the pressure inside the crucible 120 increases (e.g., increases again to 40 kPa-80 kPa), but the temperature decreases (either continuously or intermittently). During the annealing stage, the heating component 130 can continue to heat the crucible 120, thereby controlling the cooling rate of the annealing stage (e.g., controlled at 1°C / min to 3°C / min). In some embodiments, changes in pressure and / or temperature inside the crucible 120 can be used as the nodes distinguishing between different stages. For example, when the pressure inside crucible 120 begins to drop rapidly from the high pressure of the preheating stage (e.g., the pressure drop rate is greater than 20 kPa / h), the crystal growth stage begins. When the pressure inside crucible 120 begins to rise rapidly from the pressure of the crystal growth stage (e.g., the pressure rise rate is greater than 20 kPa / h), combined with the decrease in temperature, the annealing stage begins.

[0096] In some embodiments, during the preheating stage, an inert gas (e.g., argon) can be introduced into the crucible 120, and the pressure can be controlled to be maintained at 400 Pa to 800 Pa. In some embodiments, an inert gas (e.g., argon) can be introduced into the crucible 120, and the pressure can be controlled to be maintained at 450 Pa to 800 Pa, 500 Pa to 800 Pa, 550 Pa to 800 Pa, 600 Pa to 800 Pa, 650 Pa to 800 Pa, 700 Pa to 800 Pa, 750 Pa to 800 Pa, 400 Pa to 750 Pa, 450 Pa to 750 Pa, 500 Pa to 750 Pa, and 550 Pa to 750 Pa. , 600Pa~750Pa, 650Pa~750Pa, 700Pa~750Pa, 400Pa~700Pa, 450Pa~700Pa, 500Pa~700Pa, 550Pa~700Pa , 600Pa~700Pa, 650Pa~700Pa, 400Pa~650Pa, 450Pa~650Pa, 500Pa~650Pa, 550Pa~650Pa, 500Pa~650Pa, The pressure range is 400 Pa to 600 Pa, 450 Pa to 600 Pa, 500 Pa to 600 Pa, 550 Pa to 600 Pa, 400 Pa to 550 Pa, 450 Pa to 550 Pa, 500 Pa to 550 Pa, 400 Pa to 500 Pa, 450 Pa to 500 Pa, 400 Pa to 450 Pa, etc. In some embodiments, an inert gas (e.g., argon) can be introduced into the crucible to control the pressure to be maintained at one of the following pressure values: 450 Pa, 500 Pa, 550 Pa, 600 Pa, 650 Pa, 700 Pa, 750 Pa, 800 Pa, etc.

[0097] In some embodiments, during the crystal growth stage, the temperature range of the crucible 120 is maintained between 2100°C and 2400°C during the sublimation of the material 140. In some embodiments, during the crystal growth stage, the temperature range of the crucible 120 is maintained between 2150°C and 2400°C, 2200°C and 2400°C, 2250°C and 2400°C, 2300°C and 2400°C, 2350°C and 2400°C, 2100°C and 2350°C, 2150°C and 2350°C, 2200°C and 2350°C, 2250°C and 2350°C. The temperature range is selected from the following: 2300℃~2350℃, 2100℃~2300℃, 2150℃~2300℃, 2200℃~2300℃, 2250℃~2300℃, 2100℃~2250℃, 2150℃~2250℃, 2200℃~2250℃, 2100℃~2200℃, 2150℃~2200℃, 2100℃~2150℃. In some embodiments, during the crystal growth stage, when the material 140 sublimates, the temperature of the crucible 120 is maintained at one of the following temperatures: 2150℃, 2200℃, 2250℃, 2300℃, 2350℃, 2400℃.

[0098] In some embodiments, material 140 sublimates during both the preheating and crystal growth stages, and the total duration of the sublimation process can be 40h to 60h. In some embodiments, the duration of the sublimation process can be one of the following: 40h-55h, 40h-50h, 40h-45h, 45h-60h, 45h-55h, 45h-50h, 50h-60h, 50h-55h, 55h-60h, etc. In some embodiments, the constant pressure time during the constant pressure cooling stage can also be one of the following: 40h, 42h, 44h, 46h, 48h, 50h, 52h, 54h, 56h, 58h, 60h, etc.

[0099] In some embodiments, after crystal growth is completed, the annealing stage begins. At this time, a protective gas (e.g., argon) can be introduced to adjust the pressure to 40 kPa to 80 kPa, and the temperature can be reduced at a rate of 1 °C / min to 3 °C / min.

[0100] The above preparation process is merely an example, and the process parameters involved may differ in different embodiments. The order of the above steps is also not unique, and the order of the steps may be adjusted or even omitted in different embodiments. The above examples should not be construed as limiting the scope of protection of this application.

[0101] In some embodiments, the crystal growth apparatus may include a temperature control system for controlling temperature-related parameters of the heating component 130, thereby controlling the temperature and temperature gradient within the crucible 120. In some embodiments, the temperature control system may ensure that the radial temperature gradient within the crucible does not exceed a preset radial temperature gradient threshold during crystal growth. In some embodiments, the temperature control system may ensure that the axial temperature gradient within the crucible does not exceed a preset axial temperature gradient threshold during crystal growth. In some embodiments, preset radial temperature gradient thresholds and / or axial temperature gradient thresholds may be preset. In some embodiments, preset radial temperature gradient thresholds and / or axial temperature gradient thresholds may be determined based on preset conditions. In some embodiments, preset conditions may include, but are not limited to, the size, shape, and material of the crucible, the size of the seed crystal, and the type and size of the crystal to be grown.

[0102] Crystals are grown using the physical vapor transport (PVT) method. During the crystal growth stage, an axial temperature gradient is created between the material and the seed crystal within the crucible 120 by controlling the temperature field distribution inside the crucible 120. The material sublimates into a gaseous component under high temperature conditions, and this gaseous component is transported to the seed crystal driven by the axial temperature gradient. Because the temperature at the seed crystal's location is relatively low, the gaseous component can form crystals on the seed crystal surface. In some embodiments, the crystal may include, but is not limited to, silicon carbide crystals, aluminum nitride crystals, zinc oxide crystals, or zinc antimonide crystals.

[0103] In some embodiments, the heating assembly 130 may include a first heating assembly 131, which primarily heats the bottom of the crucible 120. The first heating assembly 131 may be located near the bottom of the crucible 120. If only the first heating assembly 131 is used, the axial temperature gradient within the crucible 120 may be difficult to control. If the main heating part of the heating assembly 130 is at the bottom of the crucible 120, a high heating temperature of the first heating assembly 131 may result in an excessively large axial temperature gradient within the crucible 120, leading to crystal growth defects and reducing crystal quality and yield. Specifically, due to the excessively large axial temperature gradient within the cavity, mass transfer is too rapid, resulting in an excessively fast deposition rate of gaseous components on the lower surface of the seed crystal. This leads to significant stress on the crystal growth surface, making it prone to inclusions and other defects, which in turn cause other dislocation defects, affecting crystal quality. If the heating temperature of the first heating component 131 is too low, the overall temperature inside the crucible 120 may be too low or the axial temperature gradient may be too small, which may result in insufficient driving force and a slow deposition rate of the gas phase component on the lower surface of the seed crystal, failing to meet the quality transfer requirements of the physical vapor transport method. If the axial temperature gradient is unstable, the gas phase component will be unevenly distributed in the axial direction, leading to poor quality of the grown crystal.

[0104] In some embodiments, the heating assembly 130 may include a second heating assembly 132, which primarily heats the side of the crucible 120. The second heating assembly 132 may be positioned near or around the side of the crucible 120. If only the second heating assembly 132 is provided, both the axial and radial temperature gradients within the crucible 120 may be difficult to control. If the main heating area of ​​the heating assembly 130 is on the side of the crucible 120, and the heating temperature of the first heating assembly 131 is high, it may cause a significant difference in the temperature of the gaseous components after sublimation of the material in the radial direction of the crucible 120. A large radial temperature gradient may lead to crystal growth defects, reducing crystal quality and yield. Furthermore, due to the large radial temperature gradient of the crucible 120, the concentration of the gaseous components after sublimation of the material is unevenly distributed radially, resulting in a gas phase transport path that obliquely transports from the edge to the center. This transport method results in differences in gas phase concentration at the crystal growth interface, leading to non-planar crystal growth, high internal stress, and a high susceptibility to defects such as dislocations and cracks, directly limiting the improvement of crystal quality. If the heating temperature of the first heating component 131 is too low, the axial temperature gradient within the crucible 120 may be too small, potentially resulting in insufficient driving force and a slow deposition rate of the gas phase components on the lower surface of the seed crystal, failing to meet the quality transport requirements of the physical vapor transport method.

[0105] This specification provides crystal growth equipment in some embodiments. By specifically configuring the heating component 130, the temperature distribution or temperature gradient within the crucible 120 is influenced, ensuring that the temperature gradient within the crucible 120 meets the requirements of physical vapor transport for temperature-related parameters such as radial and axial temperature gradients during crystal growth, thereby guaranteeing the quality of crystal growth.

[0106] Figure 2 is a schematic diagram of the crystal growth apparatus according to some embodiments of this specification. As shown in Figure 2, the heating assembly 130 includes a first heating assembly 131 and a second heating assembly 132. The first heating assembly 131 heats the bottom of the crucible 120, and the second heating assembly 132 heats the sides of the crucible 120. The first heating assembly 131 heating the bottom of the crucible 120 can be understood as the first heating assembly 131 primarily heating the bottom of the crucible 120, meaning the heat provided to the bottom by the first heating assembly 131 is higher than the heat provided to other parts of the crucible (such as the sides and top). Furthermore, the bottom of the crucible 120 may include the bottom wall of the crucible 120 and the area of ​​the side wall of the crucible 120 near the bottom wall. For example, if the side wall of the crucible 120 is divided into three equal regions along its axial length—upper, middle, and lower—the area of ​​the side wall of the crucible 120 near the bottom wall can be the lower region of the side wall. The second heating component 132 heating the side of the crucible 120 can be understood as the second heating component 132 being mainly used to heat the side of the crucible 120, that is, the heat provided by the second heating component 132 to the side is higher than the heat provided by the second heating component 132 to other parts of the crucible (such as the bottom and top). The side of the crucible 120 can refer to the side wall of the crucible 120.

[0107] In this embodiment, the heating assembly 130 includes both a first heating assembly 131 and a second heating assembly 132. This allows for targeted heating of both the bottom and sides of the crucible 120, and the bottom and side heating of the crucible 120 can be controlled independently. This facilitates the regulation of the temperature gradient (including axial and radial temperature gradients) within the crucible 120. By independently adjusting the heating power, heating time, and other parameters of the first heating assembly 131 and the second heating assembly 132, the bottom and side temperatures can be adjusted more flexibly to control and adjust the temperature distribution within the crucible 120. Specifically, since the first heating assembly 131 primarily heats the bottom of the crucible 120, it can provide a larger axial temperature gradient. The heating area of ​​the second heating assembly 132 can cover a relatively long axial area of ​​the crucible 120, thus helping to maintain the overall temperature within the crucible 120. Therefore, the heating temperature of the first heating assembly 131 does not need to be set too high, avoiding an excessively large axial temperature gradient within the cavity. Furthermore, due to the presence of the first heating component 131, the heating temperature of the second heating component 132 does not need to be set too high, thus avoiding an excessively large radial temperature gradient in the inner cavity.

[0108] In some embodiments, the first heating assembly 131 includes a first resistance heater 1311, which achieves heating through resistance heating. In some embodiments, the first resistance heater 1311 may be arranged along a surface parallel to the bottom wall of the crucible 120 (the wall near the bottom of the crucible) and spaced apart from the bottom wall of the crucible 120. In some embodiments, the projected coverage area of ​​the first resistance heater 1311 along the axial direction of the crucible 120 may be greater than or equal to the projected coverage area of ​​the inner cavity of the crucible 120 along the axial direction, so that the heat radiation range of the first resistance heater 1311 can cover the bottom of the crucible 120, thereby uniformly heating the material. Herein, the projected coverage area refers to the area of ​​the region covered by the projection. In some embodiments, to avoid arcing during resistance heating, the axial distance between the first resistance heater 1311 and the bottom wall of the crucible 120 may be greater than 20 mm (e.g., 25 mm or 30 mm).

[0109] Figure 3 is a schematic diagram of the structure of a resistance heater according to some embodiments of this specification. In some embodiments, as shown in Figure 3, the first resistance heater 1311 includes resistance wires 13111, which can be arranged in one or more distribution methods such as serpentine distribution, coiled distribution, row distribution, or column distribution. In some embodiments, to avoid arcing during resistance heating, the minimum spacing l between the resistance wires 13111 is in the range of 10mm-15mm (e.g., 11mm-14mm or 12mm-13mm). It should be noted that the minimum spacing l between the resistance wires 13111 can be understood as the minimum value of the spacing between the spaced resistance wires 13111 at various positions and angles. Taking a row-distributed resistance wire 13111 as an example, the minimum spacing can be the row spacing.

[0110] In some embodiments, the first resistance heater 1311 can be embedded in the bottom wall of the crucible 120. For example, a groove is provided on the bottom wall of the crucible 120, and the first resistance heater 1311 is installed in the corresponding groove. In this case, there can be a gap between the first resistance heater 1311 and the bottom wall of the crucible 120 to avoid arcing. The first resistance heater 1311 directly transfers heat to the interior of the crucible 120 through the bottom wall of the crucible 120, thereby improving heat transfer efficiency.

[0111] Figure 4 is a schematic diagram of the arrangement of the first induction coil according to some embodiments of this specification. In some embodiments, as shown in Figure 4, the first heating assembly 131 includes a first induction coil 1312, which heats the bottom of the crucible 120 by electromagnetic induction. The first induction coil 1312 is sleeved around the crucible 120 and surrounds the bottom wall of the crucible 120. In some embodiments, the bottom end of the first induction coil 1312 in the axial direction is lower than the bottom end of the crucible 120 in the axial direction. In some embodiments, the central axis of the first induction coil 1312 coincides with the central axis of the crucible 120, so that the crucible 120 is heated evenly. In some embodiments, the midpoint of the axial length of the first induction coil 1312 may be located on the plane where the bottom wall of the crucible 120 is located, or the midpoint of the axial length of the first induction coil 1312 may be located below the plane where the bottom wall of the crucible 120 is located.

[0112] In some embodiments, to improve the heating effect of the first induction coil 1312 on the bottom of the crucible 120, a graphite ring 133 is provided at the bottom of the crucible 120. The graphite ring 133 is a ring structure, and the shape of the cross-section of the graphite ring 133 perpendicular to the axis of the crucible 120 can match the shape of the body 122 of the crucible 120. For example, when the body 122 is a cylindrical tube, the graphite ring 133 is a circular ring structure. In some embodiments, the central axis of the graphite ring 133 can coincide with the central axis of the crucible 120. In some embodiments, the side of the graphite ring 133 near the crucible 120 can be connected to the bottom wall of the crucible 120. In some embodiments, the outer diameter of the graphite ring 133 can be smaller than the diameter of the bottom of the crucible. In some embodiments, to ensure higher heat generation and heat transfer efficiency, the outer diameter of the graphite ring 133 is equal to the diameter of the bottom of the crucible 120. In some embodiments, the height of the graphite ring 133 in the axial direction is 1 / 4 to 1 / 2 (e.g., 1 / 3) of the height of the crucible 120. During crystal growth, the heat concentration area of ​​the first induction coil 1312 is adjusted to the graphite ring 133, which conducts heat to the bottom of the crucible 120. At this time, the heat obtained at the bottom of the crucible 120 includes the heat conducted by the graphite ring 133 and the heat induced by the first induction coil 1312, achieving a better effect of heating the bottom of the crucible 120 by electromagnetic induction.

[0113] In some embodiments, referring to FIG2, to better heat the side of the crucible 120, the second heating assembly 132 includes a second induction coil 1321. The second induction coil 1321 is sleeved on the side of the crucible 120 and arranged around the crucible 120, achieving relatively uniform heating of the side of the crucible 120 through electromagnetic induction. In some embodiments, the bottom end of the second induction coil 1321 in the axial direction is lower than the bottom wall of the crucible 120, or the bottom end of the second induction coil 1321 in the axial direction is located on the plane of the bottom wall of the crucible 120. In some embodiments, the top end of the second induction coil 1321 in the axial direction is higher than the top end of the crucible 120 (such as the top cover of the crucible 120), or the top end of the second induction coil 1321 in the axial direction is flush with the top end of the crucible 120 (such as the top end of the second induction coil 1321 in the axial direction is located on the plane of the top cover of the crucible 120). By positioning the top and bottom ends of the second induction coil 1321 relative to the top and bottom ends of the crucible 120, the heat energy of the second induction coil 1321 can cover the entire side of the crucible 120. In some embodiments, the central axis of the second induction coil 1321 coincides with the central axis of the crucible 120, so that the heat received by the entire side of the crucible 120 is uniform.

[0114] Figure 2 shows an embodiment where the first heating assembly 131 includes a first resistance heater 1311 and the second heating assembly 132 includes a second induction coil 1321. Heating the bottom of the crucible 120 using the first resistance heater 1311 improves heating efficiency and creates a more ideal axial temperature gradient within the cavity. An embodiment where the first heating assembly 131 includes a first induction coil 1312 and the second heating assembly 132 includes a second induction coil 1321 is shown in Figure 5.

[0115] Figure 5 is a schematic diagram illustrating the arrangement of the first and second induction coils according to some embodiments of this specification. In some embodiments, as shown in Figure 5, both the first induction coil 1312 and the second induction coil 1321 are arranged around the side of the crucible 120, with the first induction coil 1312 located below the second induction coil 1321 along the axial direction of the crucible 120. The first induction coil 1312 heats the bottom and lower part of the side of the crucible 120, while the second induction coil 1321 heats the upper part of the side of the crucible 120. By using multiple induction coils to perform zoned heating of the side of the crucible 120, the temperature difference between the crystal surface and the material 140 can be well controlled, achieving a more optimal temperature gradient setting within the crucible 120. In some embodiments, the heating power of the first induction coil 1312 can be greater than the heating power of the second induction coil 1321.

[0116] In some embodiments, the bottom end of the second induction coil 1321 in the axial direction is spaced apart from the top end of the first induction coil 1312 in the axial direction to avoid mutual interference between the first induction coil 1312 and the second induction coil 1321. The top end of the second induction coil 1321 in the axial direction is located on the same horizontal line (perpendicular to the axial direction) as the top end of the crucible 120 in the axial direction, or the top end of the second induction coil 1321 in the axial direction is higher than the top end of the crucible 120 in the axial direction. The bottom end of the first induction coil 1312 in the axial direction is lower than the bottom end of the crucible 120 in the axial direction, or the bottom end of the first induction coil 1312 in the axial direction is located on the same horizontal line (perpendicular to the axial direction) as the bottom end of the crucible 120 in the axial direction. In some embodiments, the central axis of both the first induction coil 1312 and the second induction coil 1321 coincides with the central axis of the crucible 120. For further explanation of the first induction coil 1312 shown in FIG. 5, please refer to the relevant content of the first induction coil 1312 in FIG. 3.

[0117] In some embodiments, an annular spacer 134 is provided between the bottom end of the second induction coil 1321 in the axial direction and the top end of the first induction coil 1312 in the axial direction. The annular spacer 134 is used to block electromagnetic interference between the induction coils. In some embodiments, the annular spacer 134 has an annular structure and is arranged around the crucible 120. In some embodiments, the material of the annular spacer 134 is a material that can shield electromagnetic interference (e.g., aluminum, copper, iron, nickel, silver, etc.).

[0118] In some embodiments, during the crystal growth stage, to provide an axial temperature gradient, a first heating component 131 for bottom heating can be primary, and a second heating component 132 for side heating can be secondary. That is, the first heating component 131 provides more heat to the crucible 120 than the second heating component 132. In some embodiments, during the crystal growth stage, the ratio of bottom heat to side heat received by the material in the crucible 120 is 1-4 (i.e., 1:1-4:1). In some embodiments, during the crystal growth stage, the ratio of bottom heat to side heat is 3:2-4:1 (e.g., 3:1 or 2:1). Here, bottom heat refers to the heat provided by the first heating component 131 and received by the crucible 120; side heat refers to the heat provided by the second heating component 132 and received by the crucible 120. In some embodiments, the effective power ratio of the first heating component 131 to the second heating component 132 can be 3:2-4:1 (e.g., 3:1 or 2:1). In some embodiments, during the annealing stage, to minimize the radial temperature gradient inside the crystal, only the first heating component 131 may be heated. For related information on the crystal growth stages, please refer to the relevant content above.

[0119] It should be noted that the structures and arrangements of the first heating component 131 and the second heating component 132 shown in Figures 2-5 are merely illustrative and not intended to be limiting. Those skilled in the art can make modifications or adjustments to the embodiments without intellectual effort. For example, the first heating component 13 may simultaneously include a first resistance heater 1311 (in which case the first resistance heater 1311 may be encased in an electromagnetic shielding shell) and a first induction coil 1312. The first resistance heater 1311 can be arranged within a graphite ring 133, with the graphite ring 133 separating the first induction coil 1312 and the first resistance heater 1311. These modifications or adjustments are still within the scope of this specification.

[0120] In some embodiments, the second heating assembly 132 disposed on the side of the crucible 120 can heat the side of the crucible 120 by providing multiple induction coils. FIG6A is a schematic structural diagram of the second heating assembly according to some embodiments of this specification. In some embodiments, as shown in FIG6A, the second heating assembly 132 includes a second induction coil 1321 and a third induction coil 1322, the third induction coil 1322 being sleeved outside the second induction coil 1321. The structure of the third induction coil 1322 can be similar to the structure of the second induction coil 1321. In some embodiments, the axial length of the second induction coil 1321 and the third induction coil 1322 is greater than the inner cavity height of the crucible 120 along its axial direction. By using the second induction coil 1321 and the third induction coil 1322 in conjunction, the second heating assembly 132 can more flexibly control the temperature inside the crucible 120, and can also increase the maximum heat that can be obtained inside the crucible 120.

[0121] In some embodiments, the crystal growth apparatus 100 includes a first induction coil moving mechanism 60 and a second induction coil moving mechanism. The first induction coil moving mechanism 60 is used to drive the second induction coil 1321 to move along the axial direction of the crucible 120, and the first induction coil moving mechanism 60 is connected to the second induction coil 1321. The second induction coil moving mechanism is used to drive the third induction coil 1322 to move along the axial direction of the crucible 120, and the second induction coil moving mechanism is connected to the third induction coil 1322. In some embodiments of this specification, the induction coil moving mechanism drives the induction coil located on the side of the crucible 120 to move along its axial direction, which can adjust the relative position of the crucible 120 and the second heating assembly 132, thereby adjusting the position on the side of the crucible 120 where the most heat can be obtained, thereby adjusting the temperature distribution inside the crucible 120 (e.g., adjusting the position of the high-temperature wire inside the crucible 120). When the second induction coil 1321 and the third induction coil 1322 are driven to move in the same direction along the axial direction of the crucible 120, it is equivalent to keeping their relative positions unchanged. Adjusting the position of the crucible 120 will change the temperature distribution inside the crucible 120, as detailed in Figures 7 and 8. In some embodiments, when the second induction coil 1321 and the third induction coil 1322 are driven to move in opposite directions along the axial direction of the crucible 120, the heating temperature is highest at the position where the second induction coil 1321 and the third induction coil 1322 overlap. The temperature distribution inside the crucible 120 can be adjusted (e.g., by adjusting the position of the high-temperature wire inside the crucible 120) by adjusting the position of the overlapping position of the second induction coil 1321 and the third induction coil 1322 relative to the crucible 120.

[0122] Figure 6B is a schematic diagram of the structure of the second heating assembly and the first induction coil moving mechanism according to some embodiments of this specification. In some embodiments, as shown in Figure 6B, the first induction coil moving mechanism 60 may include one or more lifting rods 61 and a driving member 62, with the upper end of each lifting rod 61 connected to the driving member 62 and the lower end of the lifting rod 61 connected to the second induction coil 1321. The driving member 62 can drive the second induction coil 1321 to move axially along the crucible 120 via the lifting rods 61. The driving member 62 may include a motor, a hydraulic cylinder, a pneumatic cylinder, etc. Understandably, the lifting rod 61 may also be replaced by a combination of a lifting rope and a sheave, with the lifting rope wound around the sheave. In this case, the driving member 62 can drive the sheave to rotate, causing the lifting rope to lift or lower the second induction coil 1321 to adjust the axial position of the second induction coil 1321 relative to the crucible 120. In other embodiments, the first induction coil moving mechanism 60 may include a lifting mechanism disposed below the second induction coil 1321. For example, the lifting mechanism may include a telescopic rod and a drive member 62 for extending and retracting the telescopic rod. Driven by the drive member 62, the telescopic rod can extend to lift the second induction coil 1321 or shorten to lower the second induction coil 1321, thereby adjusting the axial position of the second induction coil 1321 relative to the crucible 120. The structure of the second induction coil moving mechanism can be similar to that of the first induction coil moving mechanism; for details, please refer to the relevant description of the first coil moving mechanism.

[0123] In some embodiments, the relative position of the crucible and the second heating assembly can also be changed by moving the crucible 120 along its axial direction. By way of example only, the crucible 120 may be mounted on a lifting platform.

[0124] Figure 7 shows the axial temperature gradient of the crucible's internal cavity at different positions. Figure 8 shows the axial temperature distribution of the crucible's internal cavity at different positions. While keeping the structure, position, and power input of the second induction coil 1321 and the third induction coil 1322 unchanged, the crucible 120 was moved equidistantly upwards by 20mm, 40mm, and 60mm from its original position along the axial direction, and equidistantly downwards by 20mm, 40mm, and 60mm, respectively, to simulate the effect of crucible position changes on the temperature of the crucible's internal cavity. That is, the only variable is the position of the crucible 120 relative to the second induction coil 1321 and the third induction coil 1322. The tops and bottoms of the second induction coil 1321 and the third induction coil 1322 are aligned. When the crucible 120 is in its original position, the bottom ends of the second induction coil 1321 and the third induction coil 1322 are located below the bottom wall of the crucible 120, and the distance between the bottom wall of the crucible 120 and the bottom ends of the second induction coil 1321 and the third induction coil 1322 is 50mm-150mm; the top ends of the second induction coil 1321 and the third induction coil 1322 are located above the top cover of the crucible 120, and the distance between the top cover 121 of the crucible 120 and the top ends of the second induction coil 1321 and the third induction coil 1322 is 50mm-100mm. In Figure 7, the horizontal axis represents the axial position within the cavity of crucible 120 (the horizontal axes of Figures 8, 9, and 11B are similar to those of Figure 7), and the vertical axis represents the temperature difference (i.e., °C) within the cavity of crucible 120. The curves in Figure 7 show the temperature changes corresponding to different axial positions of crucible 120 (relative to a reference position with a horizontal axis of 0 mm). For example, the point with a horizontal axis of 0 mm corresponds to the upper surface of the bottom wall of crucible 120 (the horizontal axes of Figures 8, 9, and 11B are similar to those of Figure 7), where the temperature difference is 0 °C. The position with a horizontal axis of 0.01 mm corresponds to 0.01 mm above the upper surface of the bottom wall. For the curve representing a 60 mm downward shift of crucible 120, the temperature difference between 0.01 mm above the upper surface of the bottom wall and the upper surface of the bottom wall of crucible 120 is approximately 4 °C. Therefore, the curves in Figure 7 represent the temperature gradient within the cavity of crucible 120. As shown in Figure 7, the overall axial temperature gradient of crucible 120 is minimized when it is moved upward by 60 mm from its original position. The axial temperature gradient within crucible 120 decreases as the height of the upward movement of crucible 120 relative to the induction coils (such as the second induction coil 1321 and the third induction coil 1322) increases. Conversely, the result is the opposite when crucible 120 is moved downward by 60 mm from its original position. Overall, as the position of crucible 120 relative to the induction coils (such as the second induction coil 1321 and the third induction coil 1322) moves from bottom to top, the internal temperature gradient within crucible 120 gradually decreases.In Figure 8, the horizontal axis represents the axial position within the inner cavity of crucible 120, and the vertical axis represents the temperature (°C) within the inner cavity of crucible 120. As shown in Figure 8, moving crucible 120 upwards has a greater impact on the temperature inside crucible 120 than moving it downwards. During the upward movement of crucible 120, the overall temperature inside the inner cavity decreases as the height of the upward movement gradually increases. During the downward movement of the crucible at equal intervals, the overall temperature change is smaller, and the temperature field changes are complex without a clear pattern. Based on Figures 7 and 8, it can be seen that the relative position of crucible 120 and the induction coil affects the overall temperature and temperature gradient inside crucible 120. By adjusting the axial positions of the second induction coil 1321 and the third induction coil 1322 relative to crucible 120, the overall temperature and temperature gradient inside crucible 120 can be adjusted.

[0125] In some embodiments, the temperature distribution inside the crucible 120 can be adjusted by adjusting the power of the second induction coil 1321 and the third induction coil 1322, as shown in Figures 9 and 10. Figure 9 is an axial temperature distribution diagram of the inner cavity of the crucible corresponding to different power levels of the third induction coil. In Figure 9, the horizontal axis represents the axial position inside the cavity of the crucible 120, and the vertical axis represents the temperature (°C) inside the cavity of the crucible 120. Figure 10 is a bar graph of the temperature difference between the seed crystal and the material surface corresponding to different power levels of the third induction coil. In Figure 10, the horizontal axis represents the power of the third induction coil 1322, and the vertical axis represents the temperature difference (°C) between the seed crystal and the material surface (the upper surface of the material inside the crucible 120). The power of the second induction coil was set to P1 = 50kW, and the power of the third induction coil P2 was adjusted to 20kW, 30kW, 40kW, 50kW, 60kW, 70kW, and 80kW respectively. The power of the third induction coil P2 was equal to the power of the second induction coil P1. The experimental group with P1 = P2 = 50kW served as the control group. Figure 9 shows that as the power of the third induction coil increased, the temperature inside the crucible gradually increased. Figure 10 shows that the temperature difference between the seed crystal and the material surface was smallest when the power of the third induction coil was 80kW, and largest when the power was 20kW. As the power of the third induction coil increased, the temperature difference between the seed crystal surface and the material surface gradually decreased. Based on Figures 9 and 10, it can be seen that the power of the induction coils (such as the second induction coil 1321 and the third induction coil 1322) will affect the overall temperature and temperature gradient inside the crucible 120. By adjusting the power of the second induction coil 1321 and the third induction coil 1322, the overall temperature and temperature gradient inside the crucible 120 can be adjusted.

[0126] In some embodiments, the crystal growth apparatus further includes a fourth induction coil 1323, which may be disposed below the second induction coil 1321 along the axial direction of the crucible 120. The fourth induction coil 1323 and the second induction coil 1321 may be spaced apart along the axial direction of the crucible 120. In some embodiments, the fourth induction coil 1323 may be primarily used to heat the material contained within the crucible 120. In some embodiments, the second induction coil 1321 may be primarily used to heat the region between the upper surface of the material within the crucible 120 and the crystal growth section. By arranging induction coils (such as the second induction coil 1321 and the fourth induction coil 1323) spaced apart along the axial direction of the crucible 120, temperature control of different regions of the crucible 120 can be performed more flexibly, thereby controlling the axial temperature gradient within the crucible 120.

[0127] Figure 11A is a schematic diagram of the structure of a second heating assembly according to some other embodiments of this specification. In some embodiments, as shown in Figure 11A, the second heating assembly 132 includes a second induction coil 1321, a third induction coil 1322, a fourth induction coil 1323, and a fifth induction coil 1324. The second induction coil 1321 and the fourth induction coil 1323 are both arranged around the side of the crucible 120. The third induction coil 1322 is sleeved outside the second induction coil 1321, and the fifth induction coil 1324 is sleeved outside the fourth induction coil 1323. The fourth induction coil 1323 is located axially below the second induction coil 1321, and the fifth induction coil 1324 is located axially below the third induction coil 1322. In some embodiments, the bottom end of the second induction coil 1321 and the top end of the fourth induction coil 1323 are spaced apart axially, and the bottom end of the third induction coil 1322 and the top end of the fifth induction coil 1324 are spaced apart axially. In some embodiments, the top end of the second induction coil 1321 is higher than the top end of the crucible 120 in the axial direction, the bottom end of the fourth induction coil 1323 is lower than the bottom end of the crucible 120 in the axial direction, and the top end of the third induction coil 1322 is higher than the top end of the crucible 120 in the axial direction, while the bottom end of the fifth induction coil 1324 is lower than the bottom end of the crucible 120 in the axial direction. In some embodiments, the central axes of the second induction coil 1321, the third induction coil 1322, the fourth induction coil 1323, and the fifth induction coil 1324 all coincide with the central axis of the crucible 120. In some embodiments, the temperature distribution inside the crucible 120 can be adjusted by adjusting the axial positions of the second induction coil 1321, the third induction coil 1322, the fourth induction coil 1323, and the fifth induction coil 1324 relative to the crucible 120, and / or by adjusting the power of the second induction coil 1321, the third induction coil 1322, the fourth induction coil 1323, and the fifth induction coil 1324, respectively.

[0128] With the above-mentioned four induction coils (second induction coil 1321, third induction coil 1322, fourth induction coil 1323 and fifth induction coil 1324), the second induction coil 1321 and the third induction coil 1322 located at the top and the fourth induction coil 1323 and the fifth induction coil 1324 located at the bottom heat different areas of the crucible 120 in the axial direction, which allows for more flexible adjustment of the radial temperature of the crucible 120 and a larger adjustable temperature range.

[0129] In some embodiments, the fourth induction coil 1323 and / or the fifth induction coil 1324 may also be connected to the induction coil moving mechanism, so that the positions of the fourth induction coil 1323 and / or the fifth induction coil 1324 relative to the crucible 120 can be changed. For example, the fourth induction coil 1323 may be connected to the third induction coil moving mechanism, and the fifth induction coil 1324 may be connected to the fourth induction coil moving mechanism. The structures of the third and fourth induction coil moving mechanisms may be similar to the structure of the first induction coil moving mechanism.

[0130] In some embodiments, the temperature distribution inside the crucible 120 can be adjusted by adjusting the power of the second induction coil 1321, the third induction coil 1322, the fourth induction coil 1323, and the fifth induction coil 1324, as shown in Figures 11B and 11C. Figure 11B is an axial temperature distribution diagram of the crucible cavity corresponding to different power levels of the fourth and fifth induction coils. In Figure 11B, the horizontal axis represents the axial position inside the crucible 120 cavity, and the vertical axis represents the temperature (°C) inside the crucible 120 cavity. Figure 11C is a bar graph of the temperature difference between the seed crystal and the material surface corresponding to different power levels of the fourth and fifth induction coils. In Figure 11C, the horizontal axis represents the power P3 of the fourth induction coil 1323 (the power P4 of the fifth induction coil 1324 = P3), and the vertical axis represents the temperature difference (°C) between the seed crystal and the material surface (the upper surface of the material inside the crucible 120). The power P1 of the second induction coil 1321 and the power P2 of the third induction coil 1322 were made equal, both at 50kW, and the power P3 of the fourth induction coil 1323 and the power P4 of the fifth induction coil 1324 were made equal. The power P3 of the fourth induction coil 1323 and the power P4 of the fifth induction coil 1324 were adjusted to be equal at 20kW, 30kW, 40kW, 50kW, 60kW, 70kW, and 80kW respectively. The experimental group with the power P1 of the second induction coil 1321, the power P2 of the third induction coil 1322, the power P3 of the fourth induction coil 1323, and the power P4 of the fifth induction coil 1324 all equal at 50kW served as the control group. As shown in Figure 11B, as the power P3 of the fourth induction coil 1323 and the power P4 of the fifth induction coil 1324 increased, the temperature inside the crucible 120 gradually increased. As shown in Figure 11C, the temperature difference between the seed crystal and the material surface is largest when the power P3 of the fourth induction coil 1323 and the power P4 of the fifth induction coil 1324 are both 80kW, and smallest when the power is 20kW. As the power P3 of the fourth induction coil 1323 and the power P4 of the fifth induction coil 1324 increase, the temperature difference between the seed crystal surface and the material surface also gradually increases. Based on Figures 11B and 11C, it can be seen that the power of the induction coils (such as the fourth induction coil 1323 and the fifth induction coil 1324) affects the overall temperature and temperature gradient inside the crucible 120. By adjusting the fourth induction coil 1323 and the fifth induction coil 1324, the overall temperature and temperature gradient inside the crucible 120 can be adjusted.

[0131] Figure 12 is a schematic diagram of a crystal growth apparatus according to some other embodiments of this specification. As shown in Figure 12, based on the above embodiments, the heating assembly 130 further includes a third heating assembly 135, which heats the top of the crucible 120. In the embodiment shown in Figure 12, the heating assembly 130 includes a first heating assembly 131, a second heating assembly 132, and a third heating assembly 135. It can be understood that the third heating assembly 135 can be provided independently (not combined with the first heating assembly 131 or the second heating assembly 132), or the third heating assembly 135 can be combined with any one of the first heating assembly 131 or the second heating assembly 132. The third heating assembly 135 heating the top of the crucible 120 can be understood as the third heating assembly 135 mainly being used to heat the top of the crucible 120, that is, the heat provided by the third heating assembly 135 to the top is higher than the heat provided by the third heating assembly 135 to other parts of the crucible (such as the sides and bottom). By combining the third heating component 135 with the first heating component 131, the third heating component 135 with the second heating component 132, or the first heating component 131, the second heating component 132, and the third heating component 135, the crucible 120 can be heated from multiple different parts. The heating of each part of the crucible 120 (e.g., bottom heating, side heating, top heating) can be controlled separately, which is beneficial for the regulation of the temperature gradient (including axial temperature gradient and radial temperature gradient) inside the crucible 120.

[0132] In some embodiments, the third heating assembly 135 includes a second resistance heater 1351, which achieves heating through resistance heating. In some embodiments, the second resistance heater 1351 may extend along a surface parallel to the top cover of the crucible 120 and be spaced apart from the top cover of the crucible 120. In some embodiments, the axial projected coverage area of ​​the second resistance heater 1351 may be greater than or equal to the axial projected coverage area of ​​the inner cavity of the crucible 120, such that the heat radiation range of the second resistance heater 1351 can encompass the interior of the crucible 120. In some embodiments, to avoid arcing during resistance heating, the axial distance between the second resistance heater 1351 and the top wall of the crucible 120 may be greater than 20 mm (e.g., greater than 25 mm or greater than 30 mm). In some embodiments, the second resistance heater 1351 includes a resistance wire; details regarding the resistance wire included in the second resistance heater 1351 can be found in the description of the resistance wire 13111. In some embodiments, the second resistance heater 1351 may be embedded in the top of the crucible 120.

[0133] In some embodiments, the third heating assembly 135 includes an induction coil that heats by electromagnetic induction. Details regarding the induction coil included in the third heating assembly 135 can be found in the description of the first induction coil 1312. For example, a graphite ring may also be disposed on the top of the crucible 120, and the induction coil of the third heating assembly 135 may at least partially surround the outside of the graphite ring on the top of the crucible 120.

[0134] In some embodiments, during the crystal growth stage, the third heating component 135 may also heat the crucible 120. In some embodiments, during the crystal growth stage, the ratio of side heat to top heat received by the material in the crucible is 1-3. In some embodiments, during the crystal growth stage, the ratio of bottom heat to top heat received by the material in the crucible is 1-8.

[0135] In some embodiments of this specification, the temperature distribution within the crucible 120 is controlled and adjusted by targeted heating of the bottom, sides, and top of the crucible 120 using a first heating component 131, a second heating component 132, and a third heating component 135, respectively. In some embodiments, during the crystal growth stage, the heat supplied to the crucible 120 by the second heating component 132, which is the heat received by the material 140 within the crucible 120, is primarily provided by the first heating component 131 for bottom heating, supplemented by the second heating components 132 and the third heating components 135 for side and top heating, respectively. In some embodiments, during the crystal growth stage, the ratio of bottom heat, side heat, and top heat is 8:3:1 to 1:1:1 (e.g., 5:3:1, 5:2:1, or 3:2:1). Wherein, bottom heat refers to the heat provided by the first heating component 131 and received by the bottom of the crucible 120; side heat refers to the heat provided by the first heating component 131 or the second heating component 132 and received by the side of the crucible 120; top heat refers to the heat provided by the third heating component 135 and received by the top of the crucible 120. In some embodiments, the effective power ratio of the first heating component 131, the second heating component 132, and the third heating component 135 can be considered as 8:3:1 to 1:1:1. In some embodiments, during the annealing stage, in order to minimize the radial temperature gradient inside the crystal, the first heating component 131 for bottom heating can be the primary heating element, and the second heating component 132 for side heating can be secondary heating element, or only the first heating component 131 at the bottom of the crucible 120 can perform work. In some embodiments, during the annealing stage, the ratio of bottom heat to side heat is 5:1 to 1.5:1 (e.g., 4:1, 3:1, 2:1).

[0136] Figure 13 is a schematic diagram of a crystal growth apparatus according to some embodiments of this specification. In some embodiments, as shown in Figure 13, the crystal growth apparatus 100 may include a second heating component 132 and a third heating component 135. By providing the second heating component 132 and the third heating component 135 on the side and top of the crucible 120 respectively, the temperature distribution within the crucible 120 can be controlled and adjusted. In some embodiments, the second heating component 132 may be used during the crystal growth stage. If a higher internal temperature of the crucible 120 is required, the third heating component 135 may be used as an auxiliary component. In some embodiments, during the annealing stage, in order to minimize the radial temperature gradient inside the crystal, only the third heating component 135 at the top of the crucible 120 performs work, which can effectively reduce the stress during the cooling process.

[0137] This specification also provides a crystal growth method, which includes: in the crystal growth stage, heating a crucible 120 using a first heating component 131 and a second heating component 132; and in the annealing stage, heating the crucible 120 using a second heating component 132 and a third heating component 135. In the crystal growth stage, to ensure a suitable axial temperature gradient to drive the gas phase components to the crystal growth interface, the cooperation of the first heating component 131 and the second heating component 132 can form a relatively ideal temperature gradient. At this time, the third heating component 135 is not working, thus preventing a decrease in the axial temperature gradient. In the annealing stage, to minimize the radial temperature gradient inside the crystal, heating can be performed primarily using the third heating component 135 and second heating component 132 as a supplementary heating element.

[0138] In some embodiments, the crystal comprises silicon carbide crystal. Graphite inclusions are generated during the growth of the silicon carbide crystal. In the early stages of crystal growth, the cavity temperature is low, the pressure of the silicon carbide vapor phase component within the crucible cavity is low, the growth rate is slow, and graphitization of the material has not yet begun. As growth progresses, the pressure of the vapor phase component within the crucible cavity gradually increases, and graphitization begins. The fine particles resulting from graphitization are highly likely to be carried to the growth surface by the convection of the vapor phase component within the crucible cavity, forming graphite inclusions within the crystal. The presence of graphite inclusions causes lattice distortion, generating stress, and can also induce defects such as microtubules, dislocations, and stacking faults, severely affecting the quality of the silicon carbide product.

[0139] Therefore, in order to suppress the formation of graphite inclusions, in some embodiments, the crystal growth apparatus 100 includes a filter structure disposed within the inner cavity of the crucible. Figure 14 is a schematic diagram of the filter structure according to some embodiments of this specification.

[0140] In some embodiments, as shown in FIG14, the filter structure 150 is located axially above the material 140 within the crucible 120. The filter structure 150 includes a through-hole 151 extending from top to bottom along the axial direction of the crucible 120. The filter structure 150 can block carbonized fine particles from reaching the growth surface under the convection of gaseous components within the crucible 120 cavity, thereby preventing the formation of graphite inclusions in the crystal. In some embodiments, the periphery of the filter structure 150 is connected to the inner wall of the crucible 120, dividing the inner cavity of the crucible 120 axially. The through-hole allows gaseous components to pass through, but the filter structure 150 blocks the passage of graphitized fine particles, thereby suppressing the formation of graphite inclusions and homogenizing the airflow. It should be noted that the through-hole 151 in FIG14 is only an example and is not intended to illustrate or limit its size.

[0141] In some embodiments, the porosity of the filter structure 150 is in the range of 5% to 40% (e.g., 10% to 35%, 15% to 25%), where porosity refers to the ratio of pore area to surface area of ​​the filter structure 150. If the porosity of the filter structure 150 is too large, it will not be able to effectively suppress the formation of graphite inclusions; if the porosity of the filter structure 150 is too small, it will affect the transport of gaseous components. When the porosity of the filter structure 150 is controlled within the range of 5% to 40%, the formation of graphite inclusions can be suppressed without affecting the transport of gaseous components, and crystals of better quality can be grown.

[0142] In some embodiments, the pore size of the through holes 151 on the filter structure 150 ranges from 5 μm to 100 μm. In some embodiments, the pore size of the through holes 151 on the filter structure 150 ranges from 5 μm to 80 μm. In some embodiments, the pore size of the through holes 151 on the filter structure 150 ranges from 10 μm to 50 μm. It should be noted that the through holes 151 in Figure 14 are for illustrative purposes only and do not represent their dimensions. In some embodiments, the through holes are axially symmetrically distributed on the filter structure 150 (the axis of symmetry can be the diameter of the filter structure 150), so that the airflow in the crucible 120 cavity is uniformly transmitted. In some embodiments, the through holes are rotationally symmetrically distributed on the filter structure 150, further so that the airflow in the crucible 120 cavity is uniformly transmitted. In some embodiments, the size and position of the through holes can be set according to the enrichment distribution of graphite in the crucible 120 cavity. It was found that the outer peripheral region of the crucible 120 cavity exhibited more severe carbonization (resulting in more fine carbonized particles). The pore size of the through-holes in the edge region of the filter structure 150 was smaller than that of the through-holes 151 in the central region of the filter structure 150, thus better preventing the fine carbonized particles from reaching the crystal. In some embodiments, the porosity of the through-holes 151 in the edge region of the filter structure 150 was greater than that in the central region. Since the pore size of the through-holes 151 in the edge region of the filter structure 150 was smaller, to avoid the edge region of the filter structure 150 obstructing the transport of gaseous components, the porosity of the through-holes 151 in the edge region of the filter structure 150 was increased. This not only better suppressed the formation of graphite inclusions but also ensured the temperature transport of gaseous components.

[0143] In some embodiments, the filter structure 150 may be made of a material that does not react with the gaseous components. In some embodiments, the filter structure 150 may be made of graphite. In some embodiments, the filter structure 150 may be made of one or more of tantalum, tungsten, titanium, and their corresponding nitrides or carbides.

[0144] Figure 15A is a schematic diagram of a crystal growth apparatus according to some embodiments of this specification. As shown in Figure 15A, the furnace chamber of the furnace body 110 includes multiple chambers, and there are multiple crucibles 120, which are respectively disposed in the multiple chambers. Specifically, one crucible 120 is disposed in each chamber. The crystal growth apparatus 100 also includes a conveying mechanism 170, which is located inside the furnace chamber, and the multiple chambers are arranged along the conveying direction of the conveying mechanism 170. The conveying mechanism 170 conveys the multiple crucibles 120 so that the multiple crucibles 120 can move between different chambers. In some embodiments, the crystal growth in the crucibles 120 in different chambers can be at different stages. In some embodiments, the temperature in different chambers is different. In some embodiments, the conveying mechanism 170 may include a belt conveying mechanism 171, a chain drive mechanism, a push rod or a pull rod, etc. A channel is provided between adjacent chambers so that the crucibles 120 can move between different chambers. The conveying mechanism 170 can be located at the top, bottom, or other positions of the furnace chamber. It should be noted that "the conveying mechanism 170 is located inside the furnace" can mean that the conveying mechanism 170 is completely located inside the furnace, or it can mean that part of the structure of the conveying mechanism 170 is located inside the furnace. The conveying mechanism 170 only needs to enable the crucible 120 to move between different chambers. As an example only, the two ends of the conveying direction of the conveying mechanism 171 can be located outside the furnace.

[0145] In some embodiments, the crystal growth in the crucibles within the multiple chambers is at the same or different stages. In some embodiments, the number of chambers is at least three. That is, the multiple chambers include a first chamber 111, a second chamber 112, and a third chamber 113. The first chamber 111, the second chamber 112, and the third chamber 113 are arranged along the transport direction. The highest temperature in the second chamber 112 is higher than the highest temperature in the first chamber 111, and the highest temperature in the second chamber 112 is higher than the highest temperature in the third chamber 113. The highest pressure in the second chamber 112 is lower than the highest pressure in the first chamber 111, and the highest pressure in the second chamber 112 is lower than the highest pressure in the third chamber 113. The temperature and pressure settings of the first chamber 111, the second chamber 112, and the third chamber 113 conform to the temperature and pressure change process during crystal growth, so that each chamber can be matched with the temperature and pressure change process during crystal growth, which is beneficial for convenient and efficient crystal growth.

[0146] Referring to the above, since the crystal growth process may include a preheating stage, a crystal growth stage, and an annealing stage, at least three chambers can be respectively configured to correspond to the preheating stage, the crystal growth stage, and the annealing stage, forming a first chamber 111, a second chamber 112, and a third chamber 113. In some embodiments, the crystal growth in the crucible 120 within the first chamber 111, the second chamber 112, and the third chamber 113 is at different stages. The crystal production in the crucible 120 within the first chamber 111 is in the preheating stage, the crystal production in the crucible 120 within the second chamber 112 is in the crystal growth stage, and the crystal production in the crucible 120 within the third chamber 113 is in the annealing stage. The temperature range within the crucible 120 of the first chamber 111 corresponds to the temperature range within the crucible 120 during the preheating stage; the temperature range within the crucible 120 of the second chamber 112 corresponds to the temperature range within the crucible 120 during the crystal growth stage; and the temperature range within the crucible 120 of the third chamber 113 corresponds to the temperature range within the crucible 120 during the annealing stage.

[0147] By corresponding the chamber configuration to the stages of crystal growth, each crucible 120 can be positioned within its respective chamber for each stage of crystal growth, and the movement of the crucible 120 between different chambers can be easily accomplished using a conveying mechanism. The temperature within each chamber only needs to be set according to the corresponding crystal growth stage and adjusted within its specified temperature range. This allows for simultaneous crystal growth in multiple crucibles 120, and eliminates the need for frequent heating and cooling of individual chambers, achieving continuous crystal production and significantly improving crystal output efficiency.

[0148] In some embodiments, an openable and closable partition 114 is provided between two adjacent chambers, which can isolate the two adjacent chambers. In some embodiments, the partition 114 can open or close the passage between the two adjacent chambers. When the partition 114 is closed, the two adjacent chambers are isolated, preventing the pressure and temperature between the two adjacent chambers from affecting each other. When it is necessary to move the crucible 120, the partition 114 can be opened to allow the crucible 120 to pass through, preventing the partition 114 from affecting the movement of the crucible 120.

[0149] In some embodiments, the crucible 120 can be heated in the first chamber 111, the second chamber 112, and the third chamber 113 using any of the heating components 130 shown in Figures 2-13. In some embodiments, the heating component 130 includes a plurality of third resistance heaters 136, which are respectively disposed in the plurality of chambers. Specifically, one third resistance heater 136 is disposed in each chamber. The third resistance heaters 136 are located at the bottom of the plurality of crucibles 120 and heat the bottom of the crucibles 120.

[0150] In some embodiments, the third resistance heater 136 is located axially below the belt conveyor 171. The axial distance between the third resistance heater 136 and the belt conveyor 171 in the crucible 120 is in the range of 30 mm to 10 mm (e.g., 25 mm, 20 mm, or 15 mm).

[0151] In some embodiments, the heating assembly 130 includes at least one sixth induction coil 137, which is disposed in at least one chamber. The sixth induction coil 137 is disposed around the crucible 120 and located on the side of the crucible 120, heating the side of the crucible 120. In some embodiments, since the crystal growth stage requires a higher temperature inside the crucible 120 (if both the axial and radial temperature gradients inside the crucible 120 are required to be high), the sixth induction coil 137 is disposed in a second chamber 112, surrounding the crucible 120 inside the second chamber 112, heating the side of the crucible 120 inside the second chamber 112, thereby increasing the temperature inside the crucible 120. In some embodiments, to prevent the sixth induction coil 137 from affecting the conveying mechanism's transport of the crucible 120, the heating assembly 130 includes at least one coil lifting device 138, which is disposed in the chamber where the sixth induction coil 137 is located, and is capable of lifting the sixth induction coil 137 axially. In some embodiments, when the sixth induction coil 137 is disposed in the second chamber 112, the coil lifting device 138 is also disposed in the second chamber 112. Furthermore, the coil lifting device 137 can adjust the position of the sixth induction coil 137 relative to the crucible 120 around which it is located along the axial direction of the crucible 120, thereby adjusting the temperature field distribution (such as the axial temperature gradient) within the crucible 120. The structure of the coil lifting device 138 can be similar to that of the first induction coil moving mechanism 60 described above; please refer to the relevant description above for details.

[0152] In some embodiments, the crystal growth apparatus further includes a plurality of heat-insulating structures 160, which are respectively disposed in a plurality of chambers. The plurality of heat-insulating structures 160 are correspondingly disposed on the outside of a plurality of crucibles 120. The heat-insulating structures 160 enclose the crucibles 120 and insulate them from the heat. In some embodiments, the heat-insulating structure 160 includes a top heat-insulating portion 161 and a side heat-insulating portion 162, with the top heat-insulating portion 161 located at the top of the crucible 120 and the side heat-insulating portion 162 located on the side of the crucible 120. In some embodiments, the top end of the side heat-insulating portion 162 is connected to the top heat-insulating portion 161 along the axial direction. In some embodiments, the top heat-insulating portion 161 is provided with a temperature measuring port 163, which penetrates the top heat-insulating portion 161 and is used for a thermometer to extend into for temperature measurement. In some embodiments, the temperature measured by the thermometer extending through the temperature measuring port 163 is the temperature of the top of the upper cover 121 of the crucible 120. In some embodiments, the thermometer extending into the temperature measuring port 163 can be configured in a retractable manner. For example, the thermometer itself is a retractable structure, or the thermometer is connected to a retractable structure. That is, when temperature needs to be measured, the retractable structure extends and the thermometer extends into the temperature measuring port 163; when the conveying mechanism 170 conveys the crucible 120, the retractable structure retracts and the thermometer leaves the temperature measuring port 163.

[0153] In some embodiments, the crystal growth apparatus 100 includes multiple chambers, each capable of individual temperature and pressure measurement, to facilitate individual control of the temperature and pressure within each chamber. In some embodiments, each chamber is equipped with a separate device for sensing temperature and pressure. Figure 15B is a schematic structural diagram of a crystal growth apparatus according to some embodiments of this specification. As shown in Figure 15B, in some embodiments, the crystal growth apparatus includes a first temperature measuring component 180, which includes a first electrical rail 181 and multiple first thermometers 182. The multiple first thermometers 182 respectively measure the temperature within the inner cavities of multiple crucibles 120. The first electrical rail 181 is located outside the crucibles 120, and the portion of each of the multiple first thermometers 182 extending out of the crucible is in sliding electrical contact with the first electrical rail 181. The first electrical rail 181 is parallel to the conveying direction of the conveying mechanism 170. The first electrical rail 181 is located inside the furnace and extends through multiple chambers. When the conveying mechanism 170 conveys the crucible 120, the first thermometer 182 moves synchronously with the crucible 120. The first thermometer 182 makes sliding electrical contact with the first electrical rail 181, thereby enabling the first electrical rail 181 to supply power to the first thermometer 182 in real time. In some embodiments, the temperature signal detected by the first thermometer 182 can be exported through the first electrical rail 181. With this configuration, the first thermometer 182 can continuously measure the temperature during the conveying process of the crucible 120 by the conveying mechanism 170, and the measured temperature can also be easily transmitted.

[0154] In some embodiments, a first thermometer is fixed at the temperature measuring port 163 for temperature measurement. A first conductive rail is located at the upper part of the crucible 120 in the axial direction. Specifically, the first thermometer is held inside the temperature measuring port 163, and the portion protruding from the temperature measuring port 163 maintains sliding electrical contact with the first conductive rail. When the crucible 120 is conveyed by the conveying mechanism 170, the first thermometer slides relative to the first conductive rail, maintaining temperature monitoring during the movement of the crucible 120. In other embodiments, the first thermometer may be fixed to the side wall or bottom wall of the crucible 120, and the first thermometer protrudes from the side wall or bottom wall of the crucible 120. This facilitates the measurement of the temperature of the material inside the crucible 120. In some embodiments, a sealing structure may be provided at the protruding position of the first thermometer on the side wall or bottom wall of the crucible 120.

[0155] In some embodiments, pressure control mechanisms may be provided in each chamber (such as the first chamber 111, the second chamber 112, and the third chamber 113) to control the pressure in each chamber respectively. In some embodiments, the pressure control mechanism may include a butterfly valve, a mechanical pump, etc.

[0156] As an example only, the transfer of a single crucible 120 between multiple chambers will be described. In the first chamber 111, the temperature is raised to a first preset temperature (e.g., 1900℃-2000℃) under a first preset pressure (e.g., high pressure of 40Kpa-80Kpa). The pressure in the second chamber 112 is raised to match that of the first chamber 111, and the temperature in the second chamber 112 is controlled within a second preset temperature range (e.g., 1900℃-2100℃). After the conveying mechanism 170 transfers the crucible 120 to the second chamber 112, depressurization growth is initiated. The pressure in the second chamber 112 can be rapidly reduced to the second preset pressure (e.g., 1Kpa-1.2Kpa) at a rate of 50Kpa / h-60Kpa / h. Growth can be carried out in the second chamber 112 for a certain period of time under the second preset pressure. During the crystal growth stage, the temperature in the second chamber 112 can be slowly increased to a third preset temperature (e.g., 2100℃-2400℃). Furthermore, the first chamber 111 needs to be cooled down. Ten hours before the end of the crystal growth stage in the crucible 120 of the second chamber 112, the first chamber 111 is opened and another crucible 120 is placed in for heating. After the crystal growth stage in the crucible 120 of the second chamber 112 is completed, the crucible 120 in the second chamber 112 is transferred to the third chamber 113. Simultaneously with the transfer of the crucible from the second chamber 112 to the third chamber 113, the other crucible 120 in the first chamber 111 is transferred to the second chamber 112 to continue growth. In the third chamber 113, the crucible 120 undergoes in-situ annealing. Specifically, in the third chamber 113, the pressure is increased to a third preset pressure (e.g., a high pressure of 40 kPa-80 kPa) and cooled at a certain cooling rate (e.g., 1°C / min to 3°C / min). After the in-situ annealing of crucible 120 in the third chamber 113 is completed, the third chamber 113 is opened and crucible 120 is removed. The crucible 120 can be circulated sequentially in the above manner.

[0157] In some embodiments, the crystal growth apparatus 100 further includes a material preparation assembly. FIG16 is a schematic structural diagram of the material preparation assembly according to some embodiments of this specification. As shown in FIG16, the crystal growth apparatus 100 further includes a material preparation assembly 190, which includes a tunnel furnace 191 and a plurality of raw material furnaces 192.

[0158] A tunnel furnace 191 refers to a device that centrally integrates material preparation processes. A tunnel furnace 191 can be understood as a furnace body providing a relatively long cavity, within which an object can move along the longer direction (hereinafter referred to as the length direction of the tunnel furnace 191). In some embodiments, the tunnel furnace 191 includes a heating chamber 1911, within which multiple raw material furnaces 192 are disposed. The heating chamber 1911 can be formed within the cavity of the tunnel furnace 191. A fourth heating assembly is provided within the heating chamber 1911 for heating the raw material furnaces 192 within the heating chamber 1911. The fourth heating assembly can heat the raw material furnaces 192 within the heating chamber to provide the temperature required for material preparation in the raw material furnaces 192. The raw material furnaces 192 serve as a material generation site. In some embodiments, the raw material furnace 192 includes a raw material furnace body 1921 and a top cover 1922. The raw material furnace body 1921 forms a receiving cavity to receive materials used for preparing raw materials. In some embodiments, the raw materials for preparing materials may include carbon powder and silicon powder. Carbon powder and silicon powder are mixed in raw material furnace 192 to produce silicon carbide material.

[0159] In some embodiments, multiple raw material furnaces 192 are sequentially arranged within the heating chamber 1911 along the length of the tunnel furnace 191 (see Figure 16). In some embodiments, the tunnel furnace 191 includes a motion drive mechanism 1912, which can drive the multiple raw material furnaces 192 to move along the length of the tunnel furnace 191. The motion drive mechanism 1912 can realize the conveying of the raw material furnaces 192 in the tunnel furnace 191. Through the arrangement of the heating chamber 1911, the fourth heating component, and the motion drive mechanism 1912, the raw material furnaces 192 can be heated in the tunnel furnace 191. The fourth heating component can control the temperature of the heating chamber, and cooperate with the motion drive mechanism 1912 to control the conveying speed and residence time of the raw material furnaces 192 in the tunnel furnace 191, thereby controlling the temperature and time of heating of the raw material furnaces 192, thus accurately realizing the preparation of materials. Since a tunnel furnace 191 is used, multiple raw material furnaces 192 can be heated simultaneously and sequentially conveyed out of the tunnel furnace 191. In addition, after the material prepared in the raw material furnace 192 is taken out, the raw material can be put back into the raw material furnace 192 and the raw material furnace 192 can be fed into the tunnel furnace 191 in a cycle, so as to realize the material preparation in a cycle and greatly improve the efficiency of material preparation.

[0160] In some embodiments, the motion drive mechanism 1912 includes a conveyor belt mechanism arranged along the length of the tunnel furnace 191. Raw material furnaces 192 are placed on the conveyor belt mechanism, which drives multiple raw material furnaces 192 to move along the length of the tunnel furnace 191. In some embodiments, multiple raw material furnaces 192 are connected sequentially. The motion drive mechanism 1912 includes a push rod 19121 or a pull rod, which is connected to one of the multiple raw material furnaces 192. By pushing the push rod 19121 or pulling the pull rod, the multiple raw material furnaces 192 can be driven to move together. In some embodiments, the push rod 19121 or pull rod is located on one side of the multiple raw material furnaces 192 as a whole, and is connected to its nearest raw material furnace 192. The motion drive mechanism 1912, using a push rod 19121 or pull rod, has a simple structure, can withstand the high temperatures inside the heating chamber 1911, and has a reduced failure rate.

[0161] In some embodiments, to reduce heat dissipation in the heating chamber 1911, the tunnel furnace 191 further includes an insulation layer 1913, which insulates the heating chamber 1911. The insulation layer 1913 can be disposed inside the heating chamber 1911 (e.g., attached to the inner wall of the heating chamber 1911) or outside the heating chamber 1911 (e.g., wrapped around the tunnel furnace 191). The insulation layer 1913 may include insulation felt, insulation coating, etc. For example, the insulation layer 1913 may be an insulation coating applied to the inner wall (which may include the top wall, bottom wall, and side walls) of the heating chamber 1911. Another example is that the insulation layer 1913 may be an insulation felt wrapped around the tunnel furnace 191 at the location corresponding to the heating chamber 1911.

[0162] In some embodiments, the heating chamber 1911, along the length of the tunnel furnace 191, sequentially includes a preheating section 19111, a heating section 19112, and a cooling section 19113, which are separated from each other. The highest temperature in the heating section 19112 is higher than the highest temperature in the preheating section 19111, and the highest temperature in the heating section 19112 is higher than the highest temperature in the cooling section 19113. That is, the tunnel furnace 191 is divided into at least three sections along its length, and the heating temperatures of the raw material furnace 192 in these at least three sections can be different. During the material preparation process, the heating of the raw material in the raw material furnace 192 involves three stages: a preheating stage, a heating stage, and a cooling stage.

[0163] During the preheating phase, since the raw material furnace 192 is placed in the heating chamber 1911, the temperature inside the raw material furnace 192 gradually or intermittently increases from room temperature to reach or approach (below) a first preset temperature. In some embodiments, the first preset temperature may be 2000°C-2200°C. During the heating phase, the temperature inside the raw material furnace 192 further increases, and after reaching a second preset temperature, it begins to be held at that temperature. In some embodiments, the second preset temperature may be 2050°C-2300°C. During the cooling phase, the temperature inside the raw material furnace 192 gradually or intermittently decreases.

[0164] In some embodiments, the temperature of the preheating section 19111 is room temperature - 2000°C, and the temperature of the heating section 19112 can be 2000-2300°C. In some embodiments, the residence time of the raw material furnace 192 in the preheating section 19111 can be 5-10 hours. In some embodiments, the residence time of the raw material furnace 192 in the heating section 19112 can be 10-50 hours. In some embodiments, the temperature of the cooling section 19113 is 2300-800°C, and the residence time of the raw material furnace 192 in the cooling section 19113 can be 20-50 hours.

[0165] The motion drive mechanism 1912 can transport multiple raw material furnaces 192 according to a preset time to control the residence time of the raw material furnaces 192 in each section (preheating section 19111, heating section 19112, and cooling section 19113) to achieve temperature control during the material preparation process. With this setup, material preparation can be carried out cyclically in multiple raw material furnaces 192, resulting in high material preparation efficiency.

[0166] In some embodiments, a fourth heating component may be disposed in the preheating section 19111 and the heating section 19112 of the heating chamber 1911. The fourth heating component is used to heat the raw material furnace 192 in the preheating section 19111 and the heating section 19112. It should be noted that the preheating of the preheating section 19111 and the heating of the heating section 19112 are only for the raw material preparation stage and do not represent a limitation on the temperature of the preheating section 19111 and the heating section 19112. That is, the temperature of the preheating section 19111 can be higher than, equal to or lower than the temperature of the heating section 19112, and the temperatures of the preheating section 19111 and the heating section 19112 can be set based on the raw material preparation requirements. In other embodiments, the fourth heating component may include a first heating element, which may be disposed in the preheating section 19111 and the heating section 19112, and the first heating element can jointly heat the preheating section 19111 and the heating section 19112. In some embodiments, depending on the location of the first heating element, the fourth heating assembly may include a second heating element and a third heating element. The second heating element may be located in the preheating section 19111, and the third heating element may be located in the heating section 19112. This allows for more flexible control of the temperatures in the preheating section 19111 and the heating section 19112. In some embodiments, the fourth heating assembly may also include a fourth heating element located in the cooling section. By controlling the heating temperature of the fourth heating element in the cooling section, the cooling rate of the material synthesized in the raw material furnace can be controlled. In some embodiments, the residence time of each raw material furnace 192 in the preheating section 19111 and the heating section 19112 can be controlled by the motion drive mechanism 1912. Combined with the heating temperature of the fourth heating assembly, the heat acquired by each raw material furnace can be controlled, thereby meeting the requirements of material preparation.

[0167] In some embodiments, the tunnel furnace 191 may be provided with multiple pressure control mechanisms to control the pressure of the preheating section 19111, the heating section 19112, and the cooling section 19113, respectively. In some embodiments, the pressure control mechanisms may include butterfly valves, mechanical pumps, etc.

[0168] In some embodiments, each of the preheating section 19111, heating section 19112, and cooling section 19113 is provided with a first temperature measuring mechanism and a first pressure measuring mechanism to measure the temperature and pressure of the preheating section 19111, heating section 19112, and cooling section 19113, respectively, so as to individually control the temperature and pressure in each area. That is, the tunnel furnace 191 may include multiple first temperature measuring mechanisms and multiple first pressure measuring mechanisms. The multiple first temperature measuring mechanisms are located at positions corresponding to different sections (preheating section 19111, heating section 19112, and cooling section 19113) within the heating chamber 1911, and the multiple first pressure measuring mechanisms are located at positions corresponding to different sections (preheating section 19111, heating section 19112, and cooling section 19113) within the heating chamber 1911. In some embodiments, the first temperature measuring mechanism may include an infrared thermometer.

[0169] In some embodiments, the tunnel furnace 191 includes a second temperature sensing component capable of measuring the temperature within a plurality of raw material furnaces 192. This configuration allows operators to know the temperature within each raw material furnace, facilitating their understanding of the temperature conditions within each furnace 192 during the raw material production process.

[0170] In some embodiments, the second temperature measuring component includes a second electrical rail and a plurality of second thermometers. The plurality of second thermometers measure the temperature inside the raw material furnace 192 through portions extending into the furnace. The second electrical rail is located outside the raw material furnace 192, and the portion of each second thermometer extending out of the furnace 192 is in sliding electrical contact with the second electrical rail. The second electrical rail is parallel to the length direction of the tunnel furnace 191. In some embodiments, the second electrical rail is located inside the heating chamber 1911 to prevent the second thermometers from extending out of the heating chamber 1911 and disrupting the temperature field within the heating chamber. Specifically, the second thermometers continuously measure the temperature inside the raw material furnace 192 and maintain sliding electrical contact with the second electrical rail. When the raw material furnace 192 moves under the drive of the motion drive mechanism 1912, the second thermometers in the raw material furnace 192 also move accordingly, sliding relative to the second electrical rail, thus maintaining temperature monitoring during the movement of the raw material furnace 192. The structure and function of the second temperature measuring component can be similar to those of the first temperature measuring component 180. The only difference is that the second temperature measuring component measures the temperature inside the raw material furnace 192. For more specific details about the second temperature measuring component, please refer to the relevant description of the first temperature measuring component 180.

[0171] In some embodiments, the tunnel furnace 191 further includes a cooling mechanism located outside the heating chamber 1911. The cooling mechanism can cool the entire furnace using methods such as water cooling or air cooling. As an example only, water-cooling pipes can be coiled around the furnace wall of the tunnel furnace 191. The cooling mechanism is used to prevent the tunnel furnace 191 from overheating and causing danger during heating. In some embodiments, because the preheating section 19111 and the heating section 19112 have high temperatures, the furnace body portion of the tunnel furnace 191 corresponding to the preheating section 19111 and the heating section 19112 is equipped with a cooling mechanism. In some embodiments, the cooling mechanism includes a double-layer water-cooling structure. The inlet of the water-cooling structure is equipped with a water flow sensor, and the outlet is equipped with a water temperature sensor to monitor the water flow and temperature of the cooling water in real time to ensure safety.

[0172] In some embodiments, the tunnel furnace 191 further includes a mixing chamber 1916, a compaction chamber 1914, and a pre-vacuum chamber 1915. The mixing chamber 1916 is used to mix raw materials (such as carbon powder and silicon powder); the compaction chamber 1914 is used to compact the raw materials; and the pre-vacuum chamber 1915 is used to extract air from the raw material furnace 192. In some embodiments, the mixing chamber 1916 includes a mixing drum and a rotating device. The mixing chamber 1916 rotates the mixing drum as a whole to mix the materials within the mixing drum. In some embodiments, the compaction chamber 1914 uses hydraulic technology (e.g., a hydraulic hammer) or other means to compact the materials. In some embodiments, the pre-vacuum chamber 1915 is equipped with a vacuum gauge to monitor the vacuum level and pressure within the raw material furnace 192 in real time. By pre-vacuuming the raw material furnace 192, the risk of explosion caused by heating the raw materials in subsequent steps can be avoided. In some embodiments, the mixing chamber 1916 further includes a pressure relief device. Because the raw materials (such as toner and silicon powder) generate high pressure in the mixing chamber after high-speed rotation, a pressure relief device is used to restore the air pressure in the mixing chamber 1916 to atmospheric pressure to ensure safety during the production process. In some embodiments, the mixing chamber includes a weighing device. The weighing device makes it easier to determine the weight of various raw materials, ensuring accurate proportions of each material.

[0173] Figure 17 is a schematic diagram of the raw material furnace according to some embodiments of this specification. In some embodiments, the raw material furnace 192 can be used to produce bulk materials. As shown in Figure 17, the raw material furnace 192 includes a furnace body 1921 and a cover 1922. The cover 1922 is provided with a seed crystal bonding surface 1923, on which a seed crystal is bonded. The raw material for producing the material is placed at the bottom of the raw material furnace 192. By controlling the temperature field distribution within the raw material furnace 192, the material is continuously sublimated and consumed, thereby growing crystalline material on the seed crystal. Specifically, by controlling the temperature field distribution within the raw material furnace 192, an axial temperature gradient is formed between the raw material and the seed crystal on the seed crystal bonding surface 1923. The material placed at the bottom of the raw material furnace 192 sublimates into a gaseous component under high temperature conditions. Driven by the axial temperature gradient, the gaseous component is transported to the seed crystal in the low-temperature region. Since the temperature at the location of the seed crystal is relatively low, the gaseous component can generate crystalline material on the surface of the seed crystal. Crystalline materials can be broken down into blocks, which can then be used as raw materials for growing crystals using the Physical Vapor Transport (PVT) method.

[0174] In some embodiments, the seed crystal bonding surface 1923 can be made of graphite. In some embodiments, the seed crystal bonding surface 1923 is the inner side of the top cover 1922, and the seed crystal can be fixedly bonded to the seed crystal bonding surface 1923. In some embodiments, the seed crystal 200 can be fixed to the seed crystal bonding surface 1923 by an adhesive. The adhesive may include, but is not limited to, epoxy resin glue, AB glue, phenolic resin glue, sugar glue, etc.

[0175] In some embodiments, the fourth heating component 1924 is disposed outside the raw material furnace 192 for heating the raw material furnace 192. In some embodiments, the fourth heating component 1924 can heat the side of the raw material furnace 192. For example, the fourth heating component 1924 is a heating tube disposed around the side of the raw material furnace 192. In some embodiments, there are multiple fourth heating components 1924, which are disposed around multiple raw material furnaces 192 respectively. This allows for more precise temperature control within each raw material furnace 192, resulting in better heating effect. In some embodiments, the fourth heating component 1924 can be disposed at the bottom of the raw material furnace 192. This creates a larger axial temperature gradient within the raw material furnace 192, which is beneficial for the transfer of sublimated raw materials. For example, the fourth heating component 1924 can be a resistance heater disposed at the bottom of the raw material furnace 192. In some embodiments, the arrangement of the fourth heating component outside the raw material furnace 192 can also refer to the arrangement of the heating component outside the crucible 120 shown in Figures 2-13. In some embodiments, each raw material furnace 192 is provided with a second temperature measuring mechanism and a second pressure measuring mechanism to measure the temperature and pressure of each raw material furnace 192 individually, so as to control the temperature and pressure inside each raw material furnace 192 individually. Since each raw material furnace 192 is provided with a corresponding fourth heating component 1924, the conditions inside each raw material furnace 192 may be different, and the second temperature measuring mechanism and the second pressure measuring mechanism can better detect the temperature and pressure inside each raw material furnace 192.

[0176] It should be noted that different embodiments may produce different beneficial effects. In different embodiments, the beneficial effects may be any one or a combination of the above, or any other possible beneficial effects.

[0177] The basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0178] Finally, it should be understood that the embodiments described in this application are merely illustrative of the principles of the embodiments of this application. Other modifications may also fall within the scope of this application. Therefore, alternative configurations of the embodiments of this application are considered as examples and not limitations, and are regarded as consistent with the teachings of this application. Accordingly, the embodiments of this application are not limited to the embodiments explicitly described and illustrated in this application.

Claims

1. A crystal growth apparatus, characterized in that, The equipment includes a furnace body, a crucible, and a heating assembly; wherein, the furnace body includes a furnace chamber, and the crucible and the heating assembly are both disposed inside the furnace chamber; the heating assembly heats the crucible.

2. The crystal growth apparatus according to claim 1, characterized in that, The heating assembly includes a first heating assembly and / or a second heating assembly, wherein the first heating assembly heats the bottom of the crucible; and the second heating assembly heats the sides of the crucible.

3. The crystal growth apparatus according to claim 2, characterized in that, The second heating assembly includes the second induction coil; the second induction coil is disposed around the side wall of the crucible; The first heating assembly includes a first induction coil, which is disposed around the bottom wall of the crucible; or, The first heating component includes a first resistance heater, which is located below the bottom wall of the crucible.

4. The crystal growth apparatus according to claim 3, characterized in that, The bottom of the crucible is provided with a graphite ring, and the first induction coil is at least partially wrapped around the outside of the graphite ring; or The first resistance heater is embedded in the bottom wall of the crucible.

5. The crystal growth apparatus according to claim 4, characterized in that, An annular spacer is provided between the first induction coil and the second induction coil, and the annular spacer is arranged around the crucible.

6. The crystal growth apparatus according to claim 3, characterized in that, The heating assembly also includes a third heating assembly that heats the top of the crucible.

7. The crystal growth apparatus according to claim 6, characterized in that, The third heating component includes a second resistance heater.

8. The crystal growth apparatus according to claim 7, characterized in that, The distances between the first resistance heater and the second resistance heater and the crucible are both greater than 20 mm; and / or, The first resistance heater and / or the second resistance heater includes resistance wires, and the minimum spacing between the resistance wires is in the range of 10mm-15mm.

9. The crystal growth apparatus according to claim 6, characterized in that, During the crystal growth stage, the ratio of bottom heat to side heat obtained by the material in the crucible is 1-4, and the ratio of side heat to top heat is 1-3; during the annealing stage, the ratio of top heat to side heat obtained by the material in the crucible is 1.5-5. The bottom heat is provided by the first heating component, the side heat is provided by the second heating component, and the top heat is provided by the third heating component.

10. The crystal growth apparatus according to claim 3, characterized in that, The second heating component also includes a third induction coil, which is sleeved on the outside of the second induction coil.

11. The crystal growth apparatus according to claim 10, characterized in that, The power of the first induction coil is greater than the power of the second induction coil.

12. The crystal growth apparatus according to claim 10, characterized in that, The device also includes: A first induction coil moving mechanism is used to drive the second induction coil to move along the axial direction of the crucible, and the first induction coil moving mechanism is connected to the second induction coil; The second induction coil moving mechanism is used to drive the third induction coil to move along the axial direction of the crucible, and the second induction coil driving mechanism is connected to the third induction coil.

13. The crystal growth apparatus according to claim 10, characterized in that, The device further includes a fourth induction coil and a fifth induction coil, wherein the fourth induction coil is located below the second induction coil in the axial direction of the crucible; The fifth induction coil is sleeved outside the fourth induction coil, and the fifth induction coil is located below the third induction coil in the axial direction of the crucible.

14. The crystal growth apparatus according to claim 1, characterized in that, The device also includes a filter structure disposed within the furnace chamber, the filter structure being located above the material in the crucible along the axial direction of the crucible, wherein the filter structure includes a through hole extending from top to bottom along the axial direction of the crucible.

15. The crystal growth apparatus according to claim 14, characterized in that, The filter structure is made of graphite; or The filter structure is made of one or more of tantalum, tungsten, titanium, and their corresponding nitrides or carbides.

16. The crystal growth apparatus according to claim 14, characterized in that, The pore size of the through holes in the edge region of the filter structure is smaller than that in the central region of the filter structure, and the porosity of the through holes in the edge region of the filter structure is greater than that in the central region of the filter structure.

17. The crystal growth apparatus according to claim 14, characterized in that, The porosity of the filter structure is in the range of 5% to 40%.

18. The crystal growth apparatus according to claim 1, characterized in that, The furnace includes multiple chambers, and there are multiple crucibles, each of which is disposed in one of the multiple chambers. The crystal growth apparatus further includes a conveying mechanism, at least a portion of which is located within the furnace chamber. The plurality of chambers are arranged along the conveying direction of the conveying mechanism, which conveys a plurality of crucibles to allow the plurality of crucibles to move between different chambers.

19. The crystal growth apparatus according to claim 18, characterized in that, The plurality of chambers form a first chamber, a second chamber, and a third chamber; the first chamber, the second chamber, and the third chamber are arranged along the conveying direction; the highest temperature in the second chamber is higher than the highest temperature in the first chamber, and the highest temperature in the second chamber is higher than the highest temperature in the third chamber; the highest pressure in the second chamber is lower than the highest pressure in the first chamber, and the highest pressure in the second chamber is lower than the highest pressure in the third chamber.

20. The crystal growth apparatus according to claim 19, characterized in that, The crystal growth process includes a preheating stage, a crystal growth stage, and an annealing stage. The crystal production in the crucible in the first chamber is in the preheating stage, the crystal production in the crucible in the second chamber is in the crystal growth stage, and the crystal production in the crucible in the third chamber is in the annealing stage.

21. The crystal growth apparatus according to claim 18, characterized in that, A passage and an openable partition are provided between two adjacent chambers.

22. The crystal growth apparatus according to claim 18, characterized in that, The heating assembly includes at least one sixth induction coil and at least one coil lifting device. The at least one sixth induction coil and at least one coil lifting device are disposed in at least one of the chambers. The coil lifting device is correspondingly connected to the sixth induction coil and is capable of lifting the sixth induction coil along the axial direction of the crucible.

23. The crystal growth apparatus according to claim 18, characterized in that, The device also includes multiple heat insulation structures, which are arranged one-to-one on the outside of multiple crucibles; each heat insulation structure includes a side heat insulation part and a top heat insulation part, and the top heat insulation part is provided with a temperature measuring port.

24. The crystal growth apparatus according to claim 18, characterized in that, The crystal growth apparatus includes a first temperature measuring component, which includes a first electrical rail and a plurality of first thermometers. The plurality of first thermometers measure the temperature in the inner cavity of the plurality of crucibles respectively. The first electrical rail is located outside the crucibles, and the portion of each of the plurality of first thermometers extending out of the crucibles is in sliding electrical contact with the first electrical rail. The first electrical rail is parallel to the conveying direction of the conveying mechanism.

25. The crystal growth apparatus according to claim 18, characterized in that, The crystal growth apparatus further includes a plurality of third resistance heaters, which are respectively disposed in the plurality of chambers and located at the bottom of the plurality of crucibles. The plurality of third resistance heaters are disposed below the conveying mechanism in the axial direction of the crucibles.

26. The crystal growth apparatus according to claim 1, characterized in that, The equipment also includes a material preparation component, which includes a tunnel furnace and multiple raw material furnaces; The tunnel furnace includes a heating chamber and a motion drive mechanism. The plurality of raw material furnaces are arranged sequentially in the heating chamber along the length of the tunnel furnace, and the motion drive mechanism drives the plurality of raw material furnaces to move along the length of the tunnel furnace. The heating chamber is equipped with a fourth heating component, which is used to heat the raw material furnace.

27. The crystal growth apparatus according to claim 26, characterized in that, The tunnel furnace also includes an insulation layer that keeps the heating chamber warm.

28. The crystal growth apparatus according to claim 26, characterized in that, The tunnel furnace also includes a cooling mechanism located outside the heating chamber.

29. The crystal growth apparatus according to claim 26, characterized in that, The heating chamber, along the length of the tunnel furnace, comprises a preheating section, a heating section, and a cooling section that are separated from each other; the highest temperature in the heating section is higher than the highest temperature in the preheating section and the highest temperature in the cooling section. Each of the preheating section, the heating section, and the cooling section is equipped with a first temperature measuring mechanism and a first pressure measuring mechanism.

30. The crystal growth apparatus according to claim 26, characterized in that, The tunnel furnace includes a second temperature measuring component capable of measuring the temperature inside each of the raw material furnaces.

31. The crystal growth apparatus according to claim 30, characterized in that, The second temperature measuring component includes a second electrical rail and a plurality of second thermometers. The plurality of second thermometers measure the temperature inside the plurality of raw material furnaces respectively. The second electrical rail is located outside the raw material furnace, and the portion of each of the plurality of second thermometers extending out of the raw material furnace is in sliding electrical contact with the second electrical rail. The second electrical rail is parallel to the length direction of the tunnel furnace.

32. The crystal growth apparatus according to claim 26, characterized in that, The plurality of raw material furnaces are connected in sequence, and the motion drive mechanism includes a push rod or a pull rod, wherein the push rod or the pull rod is connected to one of the plurality of raw material furnaces.

33. The crystal growth apparatus according to claim 26, characterized in that, The equipment also includes at least one of a mixing chamber, a compaction chamber, and a pre-vacuum chamber.

34. The crystal growth apparatus according to claim 33, characterized in that, The mixing chamber includes a pressure relief device and / or a weighing device.

35. The crystal growth apparatus according to claim 26, characterized in that, The raw material furnace includes a raw material furnace body and a top cover, and the top cover is provided with a seed crystal bonding surface.

36. The crystal growth apparatus according to claim 35, characterized in that, There are multiple fourth heating components, which are arranged around the multiple raw material furnaces respectively. Each raw material furnace is equipped with a second temperature measuring mechanism and a second pressure measuring mechanism.

37. A crystal growth method, characterized in that, Using the crystal growth apparatus of claim 6, the crystal growth process includes a crystal growth stage and an annealing stage, and the method includes: During the crystal growth stage, the crucible is heated by a first heating component and a second heating component; During the annealing stage, the crucible is heated by a second heating assembly and a third heating assembly.

Images