CN114875476B

CN114875476B - Crystal preparation device

Info

Publication number: CN114875476B
Application number: CN202210632655.5A
Authority: CN
Inventors: 王宇; 官伟明; 梁振兴; 李敏
Original assignee: Meishan Boya New Material Co ltd
Current assignee: Meishan Boya New Material Co ltd
Priority date: 2022-06-07
Filing date: 2022-06-07
Publication date: 2023-03-24
Anticipated expiration: 2042-06-07
Also published as: CN116103751A; CN116180218A; CN114875476A

Abstract

The embodiment of the specification provides a crystal preparation device, which is used for preparing crystals by a liquid phase method, and comprises the following components: the growth chamber is internally provided with at least one plate assembly, wherein the at least one plate assembly comprises a through hole; the heating assembly is used for heating the growth cavity; the connecting assembly is used for connecting the seed crystal holder to support the seed crystal; and the power assembly is used for driving the connecting assembly to rotate and/or move up and down so as to drive the seed crystal holder to rotate and/or move up and down.

Description

Crystal preparation device

Technical Field

The specification relates to the technical field of crystal preparation, in particular to a device for preparing crystals based on a liquid phase method.

Background

When crystals (e.g., silicon carbide) are prepared based on a liquid phase method (e.g., liquid Phase Epitaxy (LPE)), volatile components in the raw material move upward and even evaporate into a gaseous state, and then the gaseous state continues to overflow to an external heat-insulating component, so that the raw material is excessively consumed, and the volatilization process causes component deviation in the raw material, and crystal growth is affected. In addition, the overflowing vapor can affect the heat insulating performance of the heat insulating component. Therefore, it is necessary to provide a crystal preparation apparatus to improve the movement of the volatile component and further ensure the normal growth of the crystal.

Disclosure of Invention

One of the embodiments of the present specification provides a crystal preparation apparatus for preparing a crystal by a liquid phase method, the apparatus including: the growth chamber is internally provided with at least one plate assembly, wherein the at least one plate assembly comprises a through hole; the heating assembly is used for heating the growth cavity; the connecting assembly is used for connecting the seed crystal holder to support the seed crystal; and the power assembly is used for driving the connecting assembly to rotate and/or move up and down so as to drive the seed crystal support to rotate and/or move up and down.

In some embodiments, the through holes of adjacent plate assemblies are staggered with respect to each other.

In some embodiments, for at least one of said at least one deck plate assembly, the ratio of the sum of the open areas of said through holes to the area of the upper surface of said plate assembly is in the range of 30-80%.

In some embodiments, the density of the through holes decreases from the center to the edge of the plate assembly.

In some embodiments, the ratio of the density of through holes near the center of the plate assembly to the density of through holes near the edges of the plate assembly is in the range of 1:1-20.

In some embodiments, the through-holes have a diameter in the range of 0.1mm to 10 mm.

In some embodiments, an upper predetermined extent of the growth cavity sidewall is coated or provided with a shielding ring.

In some embodiments, the device further comprises a cavity cover and an upper heat preservation component, and carbon powder is filled in a gap between the cavity cover and the upper heat preservation component.

In some embodiments, the cavity cover comprises a raised structure.

In some embodiments, the growth cavity sidewall has a wall thickness that gradually increases in a direction from the top to the bottom of the growth cavity.

Drawings

The present description will be further explained by way of exemplary embodiments, which will be described in detail by way of the accompanying drawings. These embodiments are not intended to be limiting, and in these embodiments like numerals are used to indicate like structures, wherein:

FIG. 1 is a schematic diagram of the structure of an exemplary crystal preparation apparatus, shown in accordance with some embodiments herein;

FIG. 2 is a schematic illustration of through-holes in an exemplary plate assembly according to some embodiments of the present description;

FIG. 3 is a schematic illustration of through-holes in an exemplary plate assembly according to some embodiments of the present description;

FIG. 4 is a partial schematic structural view of an exemplary chamber cover and upper insulating member according to some embodiments of the present disclosure;

FIG. 5 is a schematic diagram of an exemplary growth chamber, shown in accordance with some embodiments herein;

FIG. 6 is a schematic diagram of an exemplary seed holder and seed according to some embodiments of the present disclosure;

FIG. 7 is a flow chart of an exemplary crystal preparation method according to some embodiments of the present disclosure.

In the figure, 100 is a crystal preparation apparatus, 110 is a growth chamber, 120 is a heating element, 111 is a plate element, 1111 is a through hole, 130 is a chamber cover, 131 is a gap, 132 is a protrusion structure, 140 is a heat-insulating element, 141 is an upper heat-insulating member, 142 is a middle heat preservation part, 143 is a cavity bottom heat preservation part, 144 is a lower heat preservation part, 150 is a seed crystal support, 160 is a connecting assembly, 170 is a cover plate, 180 is a seed crystal, 181 is a first seed crystal, 182 is a second seed crystal, and 190 is graphite paper.

Detailed Description

In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings used in the description of the embodiments will be briefly described below. It is obvious that the drawings in the following description are only examples or embodiments of the present description, and that for a person skilled in the art, without inventive effort, the present description can also be applied to other similar contexts on the basis of these drawings. Unless otherwise apparent from the context, or stated otherwise, like reference numbers in the figures refer to the same structure or operation.

It should be understood that "system", "apparatus", "unit" and/or "module" as used herein is a method for distinguishing different components, elements, parts, portions or assemblies at different levels. However, other words may be substituted by other expressions if they accomplish the same purpose.

As used in this specification and the appended claims, the terms "a," "an," "the," and/or "the" are not intended to be inclusive in the singular, but rather are intended to be inclusive in the plural, unless the context clearly dictates otherwise. In general, the terms "comprises" and "comprising" are intended to cover only the explicitly identified steps or elements as not constituting an exclusive list and that the method or apparatus may comprise further steps or elements.

FIG. 1 is a schematic diagram of the structure of an exemplary crystal preparation apparatus, according to some embodiments herein.

In some embodiments, crystal preparation apparatus 100 may prepare a crystal (e.g., silicon carbide) based on a liquid phase process. The crystal production apparatus 100 according to the embodiments of the present invention will be described in detail below with reference to the drawings, taking the production of a silicon carbide crystal as an example. It should be noted that the following examples are merely illustrative of the present disclosure and are not to be construed as limiting the present disclosure.

As shown in fig. 1, crystal preparation apparatus 100 may include a growth chamber 110 and a heating assembly 120.

The growth chamber 110 serves as a site for crystal preparation, and the heating assembly 120 is used to heat the growth chamber 110 to provide the heat (e.g., temperature field, etc.) required for crystal preparation.

In some embodiments, the material of the growth chamber 110 may be determined according to the type of crystal to be prepared. For example, in the preparation of a silicon carbide crystal, the material of growth chamber 110 may include graphite. In some embodiments, the material of the growth chamber 110 may further include molybdenum, tungsten, tantalum, and the like. In some embodiments, the growth chamber 110 may provide the raw materials needed to prepare the crystal. For example, growth chamber 110 may serve as a carbon source to provide the carbon needed to produce a silicon carbide crystal. In some embodiments, raw materials (e.g., silicon powder, carbon powder) needed to prepare the crystal may be placed within the growth chamber 110. In some embodiments, the growth cavity 110 may be the location where the raw materials form a melt. For example, under the action of the high temperature generated by the heating element 120, the silicon powder is melted into a melt (liquid state), and the carbon provided by the growth cavity 110 itself is dissolved in the silicon solution to form a solution of carbon in silicon, which is used as a liquid raw material for preparing the silicon carbide crystal by the liquid phase method. In some embodiments, to increase the solubility of carbon in silicon, a flux (e.g., aluminum, silicon-chromium alloys, li-Si alloys, ti-Si alloys, fe-Si alloys, sc-Si alloys, co-Si alloys, etc.) may be added to the raw materials.

In some embodiments, the upper predetermined extent of the inner sidewall of the growth chamber 110 may be coated or provided with a shield ring to prevent spontaneous nucleation of crystal growth by reaction of silicon near the surface of the melt with carbon from the sidewall of the growth chamber 110. In some embodiments, the material of the coating or shielding ring may be a refractory metal (e.g., rare earth metals such as tungsten, tantalum, molybdenum, chromium, etc., aluminum) or a metal compound (e.g., zirconia, alumina, etc.).

In some embodiments, the upper predetermined range may be in the range of 0-2/3 along the height of the growth cavity. In some embodiments, the upper predetermined range may be a range of 0-1/3 along the height of the growth cavity. In some embodiments, the upper predetermined range may be a range of 0-1/4 along the height of the growth cavity.

For more description of the growth chamber 110, reference may be made to other parts of the present specification (for example, fig. 5 and the description thereof), and the description thereof is omitted here.

In some embodiments, the heating assembly 120 may include an induction heating assembly, a resistive heating assembly, or the like. In some embodiments, the heating assembly 120 may be disposed around the periphery of the growth chamber 110.

In some embodiments, the heating assembly 120 may include an induction coil. In some embodiments, the induction coil may be disposed around the periphery of the growth chamber 110. In some embodiments, in order to ensure the temperature field required for crystal growth and improve the crystal growth efficiency, the height ratio of the growth chamber 110 to the induction coil needs to be within a predetermined range.

In some embodiments, the height ratio of the growth cavity 110 to the induction coil can be in the range of 1:1-1:5. In some embodiments, the height ratio of the growth cavity 110 to the induction coil can be in the range of 1. In some embodiments, the ratio of the height of the growth cavity 110 to the induction coil can be in the range of 1:2-1:4. In some embodiments, the height ratio of the growth cavity 110 to the induction coil can be in the range of 1. In some embodiments, the height ratio of growth cavity 110 to induction coil may be in the range of 1.8-1:3.

In some embodiments, at least one plate assembly 111 may be disposed within growth chamber 110. In some embodiments, the plate assembly 111 may be located within a melt within the growth chamber 110.

During the growth of the silicon carbide crystal, the melt in the growth cavity 110 is subjected to convection, and the silicon moves upwards from the bottom of the growth cavity 110 and even continuously overflows from the liquid state to the gaseous state, so that the excessive consumption of the silicon is caused. In addition, the overflowing silicon vapor may overflow out of the growth chamber 110 and attach to the heat insulation component outside the growth chamber, which may pollute the heat insulation component and affect the heat insulation performance. Correspondingly, at least one plate assembly 111 arranged in the growth cavity can change the convection condition of the melt, slow down the upward movement speed of the silicon, avoid excessive consumption, and simultaneously avoid or reduce the amount of silicon vapor overflowing out of the cavity, and avoid or reduce the pollution to the heat-insulating assembly.

In some embodiments, the material of the plate assembly 111 may be determined according to the type of crystal to be prepared. For example, in the preparation of silicon carbide crystals, the plate assembly 111 is made of the same material as the growth chamber 110 (e.g., graphite). Graphite can be used as a carbon source to provide carbon required by silicon carbide crystal preparation, and can also react with silicon to generate silicon carbide, accordingly, consumption of the growth cavity 110 can be reduced, and the use frequency of the growth cavity 110 can be further increased.

In some embodiments, the plate assembly 111 may include through holes therein. The through-holes may serve as channels for the convection or movement of the melt. In some embodiments, the through holes are designed to meet predetermined conditions in order to act as a means of slowing the upward movement of silicon while meeting convection or movement requirements. Further description can be seen in fig. 2 and 3, which are not repeated herein.

In some embodiments, when heating assembly 120 is an induction heating assembly (as shown in FIG. 1), plate assembly 111 may also serve as a heat source to provide the heat required for crystal production (e.g., the thermal energy of the melt from which the raw materials required for crystal growth are dissolved, the temperature field required for crystal growth).

In some embodiments, the plate assembly 111 (e.g., the uppermost plate assembly) may be located a predetermined distance below the melt level. In some embodiments, the distance that the plate assembly 111 (e.g., the uppermost plate assembly) is located below the melt level can affect the channels, paths, etc. through which the melt feedstock required for crystal growth is delivered to the crystal growth surface, thereby affecting the quality of the grown crystal. Therefore, the predetermined distance is within a predetermined range.

In some embodiments, the predetermined distance may be in the range of 10mm-50 mm. In some embodiments, the predetermined distance may be in the range of 15mm-45 mm. In some embodiments, the predetermined distance may be in the range of 20mm-40 mm. In some embodiments, the predetermined distance may be in the range of 25mm-35 mm. In some embodiments, the predetermined distance may be in the range of 28mm-32 mm.

In some embodiments, to improve stability of crystal growth, the plate assembly 111 (e.g., the lowermost plate assembly) may be located near the midpoint of the height of the melt or heating assembly (e.g., induction coil). In some embodiments, nearby may refer to within a preset distance. In some embodiments, the preset distances may include ± 50cm, ± 40cm, ± 30cm, ± 20cm, ± 10cm, ± 8cm, ± 6cm, ± 4cm, ± 2cm, ± 1cm, and the like. For example, the vicinity of the midpoint of the melt height may include within ± 30cm of the melt height of 1/2.

In some embodiments, the spacing between adjacent plate assemblies 111 may affect the temperature field near the crystal growth interface, the supply of feedstock (e.g., carbon, silicon) required for growth, its transport path to the crystal growth interface, and the like. Therefore, the interval between the adjacent plate assemblies 111 needs to be within a preset range.

In some embodiments, the spacing between adjacent plate assemblies 111 may be in the range of 10mm-60 mm. In some embodiments, the spacing between adjacent plate assemblies 111 may be in the range of 15mm-55 mm. In some embodiments, the spacing between adjacent plate assemblies 111 may be in the range of 20mm to 50 mm. In some embodiments, the spacing between adjacent plate assemblies 111 may be in the range of 25mm-45 mm. In some embodiments, the spacing between adjacent plate assemblies 111 may be in the range of 30mm-40 mm. In some embodiments, the spacing between adjacent plate assemblies 111 may be in the range of 34mm-36 mm.

In some embodiments, crystal preparation apparatus 100 can further include a chamber cover 130. In some embodiments, the cavity cover 130 may be shaped and sized to mate with the growth cavity 110. In some embodiments, the chamber cover 130 and the growth chamber 110 can be sealingly attached or removably attached (e.g., snapped).

In some embodiments, crystal preparation apparatus 100 can further include an incubation assembly 140 for incubating growth chamber 110. In some embodiments, the thermal insulation member 140 may be disposed around the growth chamber 110. In some embodiments of the present invention, the, the insulating member 140 may be disposed around the outside of the heating member 120.

In some embodiments, the insulation assembly 140 may include an upper insulation member 141, a middle insulation member 142, a bottom insulation member 143, and a lower insulation member 144.

In some embodiments, as shown in fig. 1, the upper insulating member 141 may be located at an upper portion of the growth chamber 110. In some embodiments, the middle insulation member 142 may be located below the lower or upper insulation member 141 of the growth chamber 110. In some embodiments, the chamber bottom insulating member 143 may be located at the bottom of the growth chamber 110. In some embodiments, the lower insulating member 144 may be located below the middle insulating member 142 and the cavity bottom insulating member 143. In some embodiments, adjacent insulating members (e.g., upper insulating member 141 and middle insulating member 142, middle insulating member 142 and lower insulating member 144, and bottom insulating member 143 and lower insulating member 144) may be removably connected (e.g., mated) to facilitate removal and replacement of damaged insulating members.

In some embodiments, each insulating member (e.g., upper insulating member 141, middle insulating member 142, bottom insulating member 143, lower insulating member 144) may include a block insulating material, a granular insulating material, a batting insulating material, a sheet insulating material, or the like. In some embodiments, the material of each insulating member may include quartz (silicon oxide), corundum (aluminum oxide), zirconia, carbon fiber, ceramics, etc. or other high temperature resistant materials (e.g., borides, carbides, nitrides, silicides, phosphides, sulfides of rare earth metals, etc.). In some embodiments, the materials of the insulating members may be the same or different.

In some embodiments, the crystal preparation apparatus 100 may further include a seed holder 150 for attaching the seed crystal. In some embodiments, the material of the seed holder 150 may include graphite. For the related description of the seed holder 150 and the seed crystal, reference may be made to other parts of this specification (e.g., fig. 6 and the description thereof), and the description thereof is omitted here.

In some embodiments, the crystal preparation apparatus 100 may further include a connection assembly 160 for connecting the seed tray 150. In some embodiments, the connection assembly 160 may be a cylinder, pyramid, or the like. In some embodiments, the connection assembly 160 may be integrally formed or formed by connecting a plurality of connection members to each other. In some embodiments, the material of the connecting member 160 may include, but is not limited to, graphite, and the like.

In some embodiments, the crystal preparation apparatus 100 may further include a power assembly (not shown) for rotating and/or moving up and down the connection assembly 160 to rotate and/or move up and down the seed tray 150 to grow the crystal.

In some embodiments, the crystal preparation apparatus 100 may further include a cover plate 170. In some embodiments, the cover plate 170 may be used to reduce crystal cracking. In some embodiments, the cover plate 170 may be positioned above the upper insulating member 141. In some embodiments, the cover plate 170 may be a cylinder, pyramid, or the like. In some embodiments, the cover plate 170 may be made of the same material as or different from the insulation assembly 140.

In some embodiments, as shown in fig. 1, the chamber cover 130, the upper insulating member 141, and the cover plate 170 are provided with holes therethrough to allow the connection assembly 160 and the seed holder 150 to pass therethrough for rotation and/or up-and-down movement.

In some embodiments, the size of the holes in the cover plate 170 may affect the amount of silicon volatilized. For example, if the size of the holes is too large, heat may be dissipated from the holes, resulting in increased thermal energy that needs to be provided by the heating assembly, which in turn results in increased melt temperature and increased volatilization of the silicon. The small size of the hole in the cover plate 170 may prevent the connection assembly 160 and the seed holder 150 from rotating and/or moving up and down, thereby preventing the crystal from being grown normally. Therefore, the diameter of the hole of the cover plate 170 is within a predetermined range.

In some embodiments, the diameter of the holes in the cover plate 170 may be in the range of 20mm-150 mm. In some embodiments, the diameter of the holes in the cover plate 170 may be in the range of 40mm to 120 mm. In some embodiments, the diameter of the holes in the cover plate 170 may be in the range of 50mm to 100 mm. In some embodiments, the diameter of the holes in the cover plate 170 may be in the range of 70mm to 80 mm.

It should be noted that the above description of crystal preparation apparatus 100 is intended for purposes of illustration and description only and is not intended to limit the scope of applicability of the present application. Various modifications and alterations to crystal preparation apparatus 100 will be apparent to those skilled in the art in light of the present disclosure. However, such modifications and variations are intended to be within the scope of the present application.

FIG. 2 is a schematic illustration of through-holes on an exemplary plate assembly, shown in accordance with some embodiments herein. FIG. 3 is a schematic illustration of through-holes on an exemplary plate assembly, shown in accordance with some embodiments herein.

In some embodiments, as shown in fig. 2 and 3, the plate assembly 111 may include through holes 1111 therethrough. In some embodiments, through-hole 1111 may extend through plate assembly 111. In some embodiments, the shape of the through-hole 1111 may include a regular or irregular shape such as a circle, an ellipse, a polygon, a star, and the like. In some embodiments, the through-holes 1111 shapes on one plate assembly 111 may be the same or different. In some embodiments, the shape of the through-holes 1111 on different plate assemblies 111 may be the same or different.

In some embodiments, the through holes 1111 of adjacent plate assemblies 111 may be staggered with respect to each other. For example, as shown in FIG. 2, via 1111 (shown in solid line in FIG. 2) on an upper board assembly does not coincide with via 1111' (shown in dashed line in FIG. 2) on a lower board assembly. In some embodiments, staggered may mean not overlapping or partially overlapping.

Through the design that the through holes 1111 on the adjacent plate assemblies 111 are staggered with each other, the convection of the melt in the growth cavity 110 can be adjusted, the rising speed of the volatile components (such as silicon) is reduced, the volatilization amount of the volatile components (such as silicon) on the surface of the melt is reduced, silicon carbide particles generated by the reaction of the volatile components (such as silicon vapor) and graphite of the growth cavity 110 are reduced, the pollution or damage to the heat-insulating assembly caused by the volatile silicon or the generated silicon carbide particles attached to the upper heat-insulating assembly can be further reduced, the heat-insulating performance of the heat-insulating assembly is ensured, and the normal growth of the crystal can be further ensured.

The ratio of the sum of the opening areas of the through holes 1111 to the area of the upper surface of the plate assembly 111 where the through holes 1111 are located affects the convection of the melt in the growth chamber 110, and thus the normal growth of the crystal. For example, the ratio of the sum of the opening areas of the through holes 1111 to the area of the upper surface of the plate assembly 111 where the through holes 1111 are located is too large to effectively improve the silicon lifting speed and accordingly to effectively reduce the silicon volatilization on the melt surface. For another example, if the ratio of the total opening area of the through holes 1111 to the surface area of the plate assembly 111 where the through holes 1111 are located is too small, the resistance to upward movement of the melt increases, and it is not guaranteed that a sufficient amount of melt can move near the seed crystal, thereby affecting the crystal growth rate. Therefore, in some embodiments, the ratio of the sum of the opening areas of the through holes 1111 to the area of the upper surface of the board assembly 111 where the through holes 1111 are located should satisfy a predetermined requirement.

In some embodiments, for at least one of the at least one deck assembly 111, the ratio of the sum of the open areas of the through-holes 1111 to the area of the upper surface of the deck assembly 111 may be in the range of 30% -80%. In some embodiments, for at least one of the at least one deck assembly 111, the ratio of the sum of the open areas of the through-holes 1111 to the area of the upper surface of the deck assembly 111 may be in the range of 35% -75%. In some embodiments, for at least one of the at least one deck assembly 111, the ratio of the sum of the open areas of the through-holes 1111 to the area of the upper surface of the deck assembly 111 may be in the range of 40% -70%. In some embodiments, for at least one of the at least one deck assembly 111, the ratio of the sum of the opening areas of the through holes 1111 to the area of the upper surface of the deck assembly 111 may be in the range of 45% -65%. In some embodiments, for at least one of the at least one deck assembly 111, the ratio of the sum of the open areas of the through-holes 1111 to the area of the upper surface of the deck assembly 111 may be in the range of 50% -60%. In some embodiments, for at least one of the at least one deck assembly 111, the ratio of the sum of the opening areas of the through holes 1111 to the area of the upper surface of the deck assembly 111 may be in the range of 52% -58%. In some embodiments, for at least one of the at least one deck assembly 111, the ratio of the sum of the open areas of the through-holes 1111 to the area of the upper surface of the deck assembly 111 may be in the range of 54% -56%.

In some embodiments, the ratio of the sum of the opening areas of the through holes 1111 to the area of the upper surface of the board assembly 111 where the through holes 1111 are located may be the same or different for different board assemblies 111. In some embodiments, the ratio of the sum of the open areas of the through-holes 1111 to the area of the upper surface of the plate assembly 111 where the through-holes 1111 are located may gradually decrease or increase in the direction from the bottom of the growth chamber 110 to the top of the growth chamber 110. For example, as shown in fig. 2, the ratio of the sum of the opening areas of the through holes 1111 (shown by the solid line portion in fig. 2) on the upper plate member to the upper surface area of the plate member may be smaller than the ratio of the sum of the opening areas of the through holes 1111' (shown by the dotted line portion in fig. 2) on the lower plate member to the upper surface area of the plate member.

In some embodiments, as shown in fig. 3, the density of the through-holes 1111 (e.g., the number of through-holes 1111 per unit area) may gradually decrease from the center to the edge of the plate assembly 111. In some embodiments, the density of through holes near the center of the plate assembly 111 may be higher than the density of through holes near the edges of the plate assembly 111. Accordingly, it is possible to ensure that a sufficient amount of melt can move upward from the through hole 1111 located near the center of the plate assembly 111 to the seed crystal to crystallographically grow a crystal, and to ensure crystal production efficiency while improving convection of the melt to improve excessive consumption of silicon.

It should be noted that in the present embodiment, "near" may mean within a preset distance. In some embodiments, the preset distance may include 10cm, 8cm, 6cm, 4cm, 2cm, 1cm, and the like. In some embodiments, the "near center" of the plate assembly 111 may refer to an area of the plate assembly centered at the center of the plate assembly 111 and having a radius of a predetermined distance. In some embodiments, the "near edge" of the plate assembly 111 may refer to an area of the plate assembly that is within a predetermined distance from the edge of the plate assembly 111.

Too small a ratio of the density of the through holes near the center of the plate assembly 111 to the density of the through holes near the edge of the plate assembly 111 may result in natural nucleation or a high rate of natural nucleation of silicon carbide on the inner wall of the growth chamber 110, while too large a ratio of the density of the through holes near the center of the plate assembly 111 to the density of the through holes near the edge of the plate assembly 111 may result in too fast growth of the crystal center, and easy formation of a wrap and cracking. Therefore, in some embodiments, the ratio of the density of the through holes near the center of the plate assembly 111 to the density of the through holes near the edge of the plate assembly 111 needs to be within a predetermined range.

In some embodiments, the ratio of the density of through-holes near the center of the plate assembly 111 to the density of through-holes near the edges of the plate assembly 111 may be in the range of 1:1-20. In some embodiments, the ratio of the density of through-holes near the center of the plate assembly 111 to the density of through-holes near the edges of the plate assembly 111 may be in the range of 1:1-18. In some embodiments, the ratio of the density of through-holes near the center of the plate assembly 111 to the density of through-holes near the edges of the plate assembly 111 may be in the range of 1:1-16. In some embodiments, the ratio of the density of through-holes near the center of the plate assembly 111 to the density of through-holes near the edges of the plate assembly 111 may be in the range of 1:1-14. In some embodiments, the ratio of the density of through holes near the center of the plate assembly 111 to the density of through holes near the edges of the plate assembly 111 may be in the range of 1:1-12. In some embodiments, the ratio of the density of through-holes near the center of the plate assembly 111 to the density of through-holes near the edges of the plate assembly 111 may be in the range of 1:1-10. In some embodiments, the ratio of the density of through-holes near the center of the plate assembly 111 to the density of through-holes near the edges of the plate assembly 111 may be in the range of 1:1-8:1. In some embodiments, the ratio of the density of through-holes near the center of the plate assembly 111 to the density of through-holes near the edges of the plate assembly 111 may be in the range of 1:1-6:1. In some embodiments, the ratio of the density of through-holes near the center of the plate assembly 111 to the density of through-holes near the edges of the plate assembly 111 may be in the range of 1:1-5:1. In some embodiments, the ratio of the density of through-holes near the center of the plate assembly 111 to the density of through-holes near the edges of the plate assembly 111 may be in the range of 1.5. In some embodiments, the ratio of the density of through-holes near the center of the plate assembly 111 to the density of through-holes near the edges of the plate assembly 111 may be in the range of 2:1-4:1. In some embodiments of the present invention, the, the ratio of the through hole density near the center of the plate assembly 111 to the through hole density near the edge of the plate assembly 111 may be in the range of 2.5. In some embodiments, the ratio of the density of through holes near the center of the plate assembly 111 to the density of through holes near the edge of the plate assembly 111 may be in the range of 2.8.

The diameter of the through holes 1111 will affect the convection of the melt in the growth chamber 110, and thus the normal growth of the crystal. For example, the diameter of the through holes 1111 is too large to effectively improve the silicon lifting speed, and accordingly, the silicon volatilization on the melt surface cannot be effectively reduced. For another example, if the diameter of the through hole 1111 is too small, the resistance to upward movement of the melt increases, and it is not guaranteed that a sufficient amount of melt can move to the vicinity of the seed crystal, thereby affecting the crystal growth rate. Therefore, in some embodiments, the diameter of the through hole 1111 is required to satisfy a predetermined requirement.

In some embodiments, the diameter of the through-holes 1111 may be in the range of 0.1mm to 10 mm. In some embodiments, the diameter of the through-holes 1111 may be in the range of 0.1mm to 9 mm. In some embodiments, the diameter of the through-holes 1111 may be in the range of 0.1mm to 8 mm. In some embodiments, the diameter of the through-holes 1111 may be in the range of 0.1mm to 7 mm. In some embodiments, the diameter of through-hole 1111 may be in the range of 0.1mm to 6 mm. In some embodiments, the diameter of the through-holes 1111 may be in the range of 0.1mm to 5 mm. In some embodiments, the diameter of the through-holes 1111 may be in the range of 0.1mm to 5 mm. In some embodiments, the diameter of the through-holes 1111 may be in the range of 0.5mm to 4.5 mm. In some embodiments, the diameter of the through-holes 1111 may be in the range of 1mm-4 mm. In some embodiments, the diameter of the through-holes 1111 may be in the range of 1.5mm to 3.5 mm. In some embodiments, the diameter of the through-holes 1111 may be in the range of 2mm-3 mm. In some embodiments, the diameter of the through-holes 1111 may be in the range of 2.4mm to 2.6 mm.

FIG. 4 is a partial schematic structural view of an exemplary chamber cover and upper insulating member according to some embodiments of the present disclosure.

As previously described, during crystal preparation, silicon may move upward from the bottom of the growth chamber 110, even evaporating into a gaseous state and continuing to overflow as silicon vapor. The silicon vapor may overflow the cavity cover 130 and adhere to the surface of the upper thermal insulation member 141 when encountering condensation, thereby affecting the thermal insulation performance. Therefore, in some embodiments, as shown in fig. 4, the cavity cover 130 and the upper thermal insulation member 141 may have a gap 131, and the gap 131 may be filled with carbon powder, so as to allow the volatilized silicon vapor to react with the carbon powder, thereby preventing the silicon vapor from overflowing and adhering to the surface of the upper thermal insulation member 141 when encountering condensation, or preventing silicon carbide particles generated by the reaction of the silicon vapor and the growth cavity 110 from adhering to the thermal insulation member and affecting the thermal insulation performance thereof.

In some embodiments, as shown in fig. 4, the cavity cover 130 may further include a raised structure 132. Due to the lower temperature (lower than the melt temperature) near the raised structures 132, a portion of the silicon vapor may condense at the raised structures 132 to slow or reduce the escape of silicon vapor and reduce the contamination of the upper thermal assembly 141. After the crystal growth is finished, the protruding structure 132 can be cleaned, and the subsequent use is convenient.

Fig. 5 is a schematic diagram of an exemplary growth chamber, shown in accordance with some embodiments herein.

In conjunction with the foregoing, in the crystal preparation process, the raw materials are melted into a melt (liquid state) and crystal growth is performed on the basis of the melt, and the growth chamber 110 is required to provide a carbon source required for crystal growth. Therefore, the bottom (or middle or lower) of the growth chamber 110 is at a higher temperature and is consumed more quickly.

Therefore, in some embodiments, the wall thickness of the sidewall of the growth chamber 110 is gradually increased along the direction from the top to the bottom of the growth chamber 110 (as shown by the arrow in fig. 5), so that excessive consumption and thinning of the bottom can be avoided, and the number of uses of the growth chamber 110 can be further increased.

Fig. 6 is a schematic diagram of an exemplary seed holder and seed according to some embodiments of the present disclosure.

In the process of preparing the crystal, if the seed crystal is too thin, the phenomenon of burning through is easy to occur, the preparation effect of the crystal is influenced, and because the seed crystal is too thin, the seed crystal holder can inevitably contact with the melt to generate the crystal with the crystal form and/or the crystal orientation different from that of the seed crystal, and further crystal defects are generated; and if the seed crystal with larger thickness is directly used, the cost for preparing the seed crystal is greatly increased.

Thus, in some embodiments, seed crystal 180 may include at least two layers of seed crystals, wherein the seed crystal used for crystal growth (i.e., the lowermost seed crystal in direct contact with the melt) may be of higher quality and the seed crystals of the other layers may be of relatively lower quality, which in turn may reduce costs while increasing the overall thickness of the seed crystal.

In some embodiments, as shown in fig. 6, the at least two layers of seed crystals may include a first seed crystal 181 and a second seed crystal 182, wherein the mass of the first seed crystal 181 may be lower than the mass of the second seed crystal 182.

In some embodiments, the thickness of the first seed crystal 181 may be greater than the thickness of the second seed crystal 182, provided that the second seed crystal 182 meets the crystal growth requirements, to further reduce the cost of the seed crystal 180.

In some embodiments, the bonding manner between the seed holder 150 and the first seed crystal 181, the first seed crystal 181 and the second seed crystal 182 may include, but is not limited to, bonding, optical glue, and the like.

Since the seed holder 150 inevitably has a certain porosity, the gas phase substance accumulated in the gap or pore region on the back surface of the seed crystal (for example, the bonding surface of the first seed crystal 181 and the seed holder 150) can escape, and thus defects (for example, planar hexagonal void defects) can be generated in the finally prepared crystal.

Accordingly, in some embodiments, as shown in fig. 6, graphite paper 190 may be filled between the seed holder 150 and the seed crystal 180 (first seed crystal 181). The graphite paper 190 is soft and has high flatness, so that the porosity of a bonding surface can be reduced, the back surface of the seed crystal is prevented from being heated unevenly, the generation of subsequent defects is reduced, and the bonding strength between the seed crystal holder 150 and the seed crystal 180 (for example, the first seed crystal 181) is improved.

FIG. 7 is a flow chart of an exemplary crystal preparation method according to some embodiments of the present disclosure. In some embodiments, the process 700 may be performed by one or more components of a crystal preparation apparatus (e.g., the crystal preparation apparatus 100). In some embodiments, the process 700 may be performed automatically by a control system. For example, the process 700 may be implemented by control instructions, and the control system controls each component to complete each operation of the process 700 based on the control instructions. In some embodiments, the process 700 may be performed semi-automatically. For example, one or more operations of flow 700 may be performed manually by an operator. In some embodiments, one or more additional operations not described may be added and/or one or more operations discussed herein may be deleted upon completion of flow 700. Additionally, the order of the operations shown in FIG. 7 is not limiting. As shown in fig. 7, the process 700 includes the following steps.

Step 710, placing a feedstock within a growth chamber.

In some embodiments, feedstock may refer to raw materials required to grow a crystal. For example, in growing silicon carbide crystals, the feedstock can include silicon (e.g., silicon powder, silicon wafers, silicon chunks). As another example, when growing silicon carbide crystals, the starting materials may include silicon and carbon (e.g., carbon powder, carbon blocks, carbon particles). In some embodiments, the feedstock comprises carbon powder, carbon blocks, or carbon particles, which may increase the number of uses of the growth chamber. In some embodiments, the feedstock may also include a fluxing agent for increasing the solubility of carbon in silicon. In some embodiments, the flux may include, but is not limited to, aluminum, silicon-chromium alloys, li-Si alloys, ti-Si alloys, fe-Si alloys, sc-Si alloys, co-Si alloys.

In some embodiments, at least one plate assembly may be disposed within the growth chamber. For the description of the growth chamber (e.g., the growth chamber 110) and the at least one plate assembly (e.g., the plate assembly 111), reference may be made to other parts of this specification (e.g., fig. 1-5 and the description thereof), which are not repeated herein.

Step 720, the growth cavity is heated by the heating assembly to melt the raw materials into a melt.

For example, when growing silicon carbide crystals, the raw materials melt to form a solution of carbon in silicon as the liquid raw material for crystal growth.

For a description of the heating element (e.g., the heating element 120), reference may be made to other parts of the present specification (e.g., fig. 1 and the description thereof), and the description thereof is omitted here.

In some embodiments, the ratio of the melt height to the growth chamber height is within a predetermined range to increase feedstock utilization. In some embodiments, the ratio of the melt to growth cavity height may be in the range of 1:1-1:5. In some embodiments, the ratio of the height of the melt to the growth cavity may be in the range of 1.5-1. In some embodiments, the ratio of the melt to growth cavity height may be in the range of 1:2-1:4. In some embodiments, the ratio of the height of the melt to the growth cavity may be in the range of 1. In some embodiments, the ratio of the height of the melt to the growth cavity may be in the range of 1.8 to 1:3.

In some embodiments, to improve stability of crystal growth, the melt level may be located near the midpoint of the height of the heating assembly (e.g., induction coil). In some embodiments, nearby may refer to within a preset distance. In some embodiments, the preset distances may include ± 50cm, ± 40cm, ± 30cm, ± 20cm, ± 10cm, ± 8cm, ± 6cm, ± 4cm, ± 2cm, ± 1cm, and the like. For example, after the feedstock material is melted into a melt, the melt level may be within ± 30cm of the height 1/2 of the heating assembly (e.g., induction coil).

Step 730, adhering the seed crystal to the seed crystal holder.

In some embodiments, the seed crystals may include at least two layers of seed crystals. In some embodiments, the at least two layers of seed crystals may include a first seed crystal and a second seed crystal, the first seed crystal may be bonded to the seed receptacle, and the second seed crystal may be bonded to the first seed crystal. In some embodiments, the mass of the first seed may be lower than the mass of the second seed.

In some embodiments, before the seed crystal is bonded on the seed crystal support, graphite paper can be bonded on the seed crystal support, so that the graphite paper is positioned between the seed crystal support and the seed crystal. In some embodiments, the seed crystal and/or graphite paper may be concentric with the seed holder.

In some embodiments, the thickness of the graphite paper may be in the range of 0.5mm to 1mm. In some embodiments, the thickness of the graphite paper may be in the range of 0.6mm to 0.9 mm. In some embodiments, the thickness of the graphite paper may be in the range of 0.5mm to 1mm. In some embodiments, the thickness of the graphite paper may be in the range of 0.7mm to 0.8 mm.

In some embodiments, in order to ensure the bonding strength between the graphite paper, the first seed crystal and the second seed crystal, and to ensure the crystal quality. The flatness of the surface of the first seed crystal needs to meet a preset condition. In some embodiments, the flatness of the surface of the first seed crystal adhered to the graphite paper may be less than 0.01mm. In some embodiments, the flatness of the surface of the first seed adhered to the second seed may be in the range of 0.005mm to 0.008 mm. In some embodiments, the flatness of the surface of the first seed crystal adhered to the second seed crystal may be in the range of 0.006mm to 0.007 mm.

For a description of the seed crystal (e.g., seed crystal 180) and the seed holder (e.g., seed holder 150), reference may be made to other parts of the present specification (e.g., fig. 6 and the description thereof), which are not repeated herein.

And 740, descending the seed crystal holder adhered with the seed crystal to enable the seed crystal to contact the melt.

In some embodiments, the connection assembly may be lowered by a power assembly to lower the seed holder to bring the seed into contact with the melt.

A crystal is prepared based on the seed crystal and the melt, step 750.

In some embodiments, the coupling assembly may be rotated and/or moved up and down by a power assembly to rotate and/or move up and down the seed holder, where the melt may condense to crystallize for growing the crystal.

During the crystal growth process, the melt in the growth cavity generates convection, the silicon at the lower part moves upwards, part of the silicon can be blocked by the plate assembly arranged in the growth cavity, and part of the silicon can continue to move upwards through the through holes in the plate assembly. Due to the staggering of the through holes in adjacent plate assemblies, a portion of the silicon that continues to move upward is blocked by the plate assembly above. Therefore, the silicon which flows to the upper surface of the melt through the melt convection can be obviously reduced, correspondingly, the volatilization of the silicon on the upper surface of the melt can be reduced, the pollution degree of the heat insulation component can be further reduced, the heat insulation performance of the heat insulation component can be maintained, and the normal growth of the crystal can be further ensured.

It should be noted that the above description related to the flow 700 is only for illustration and explanation, and does not limit the applicable scope of the present application. Various modifications and changes to flow 700 may occur to those skilled in the art upon review of the present application. However, such modifications and variations are still within the scope of the present application.

The beneficial effects that may be brought by the embodiments of the present description include, but are not limited to: (1) At least one plate assembly is arranged in the growth cavity, and the plate assembly is made of graphite and can be used as a carbon source to provide raw materials required by preparation of the silicon carbide crystal; (2) The plate assemblies comprise through holes, the through holes on adjacent plate assemblies are designed in a staggered mode, convection of melt in the growth cavity can be adjusted, the rising speed of volatile components (such as silicon) is reduced, the volatilization amount of the volatile components (such as silicon) on the surface of the melt is reduced, excessive consumption of the volatile components is reduced, silicon carbide particles generated by reaction of the volatile components (such as silicon vapor) and the growth cavity can be reduced, the pollution degree of the heat insulation assembly can be further reduced, the heat insulation performance of the heat insulation assembly is guaranteed, and normal growth of crystals can be further guaranteed; (3) The upper preset range of the inner side wall of the growth cavity is coated with a coating or provided with a shielding ring, so that spontaneous nucleation and crystallization growth caused by the reaction of silicon on the surface of the melt and carbon on the side wall of the growth cavity can be avoided; (4) A gap is formed between the cavity cover and the upper heat-insulating part, carbon powder is filled in the gap, and the carbon powder can react with volatilized silicon vapor to prevent the silicon vapor from overflowing to the heat-insulating component or prevent silicon carbide particles generated by the reaction of the silicon vapor and the growth cavity from being attached to the heat-insulating component to influence the heat-insulating property of the heat-insulating component; (5) The cavity cover comprises a convex structure, so that part of silicon vapor can be condensed at the convex structure, the overflow of the silicon vapor is slowed down or reduced, and the pollution degree of the heat-insulation component is reduced; (6) The seed crystal comprises at least two layers of seed crystals, so that the thickness of the seed crystal can be increased, the risk of the seed crystal being burnt through is reduced, and the quality of the prepared crystal can be further ensured; (7) The quality of the first seed crystal bonded with the seed crystal support can be lower than that of the second seed crystal bonded with the first seed crystal, so that the seed crystal cost is reduced, and the crystal preparation cost is further reduced. It is to be noted that different embodiments may produce different advantages, and in different embodiments, any one or combination of the above advantages may be produced, or any other advantages may be obtained.

Having thus described the basic concept, it will be apparent to those skilled in the art that the foregoing detailed disclosure is to be regarded as illustrative only and not as limiting the present specification. Various modifications, improvements and adaptations to the present description may occur to those skilled in the art, although not explicitly described herein. Such modifications, improvements and adaptations are proposed in the present specification and thus fall within the spirit and scope of the exemplary embodiments of the present specification.

Also, the description uses specific words to describe embodiments of the description. Reference to "one embodiment," "an embodiment," and/or "some embodiments" means a feature, structure, or characteristic described in connection with at least one embodiment of the specification. Therefore, it is emphasized and should be appreciated that two or more references to "an embodiment" or "one embodiment" or "an alternative embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, some features, structures, or characteristics of one or more embodiments of the specification may be combined as appropriate.

Similarly, it should be noted that in the preceding description of embodiments of the present specification, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure aiding in the understanding of one or more of the embodiments. This method of disclosure, however, is not intended to imply that more features than are expressly recited in a claim. Indeed, the embodiments may be characterized as having less than all of the features of a single embodiment disclosed above.

Numerals describing the number of components, attributes, etc. are used in some embodiments, it being understood that such numerals used in the description of the embodiments are modified in some instances by the use of the modifier "about", "approximately" or "substantially". Unless otherwise indicated, "about", "approximately" or "substantially" indicates that the number allows a variation of ± 20%. Accordingly, in some embodiments, the numerical parameters set forth in the specification and claims are approximations that may vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameter should take into account the specified significant digits and employ a general digit preserving approach. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the range are approximations, in the specific examples, such numerical values are set forth as precisely as possible within the scope of the application.

For each patent, patent application publication, and other material, such as articles, books, specifications, publications, documents, etc., cited in this specification, the entire contents of each are hereby incorporated by reference into this specification. Except where the application history document does not conform to or conflict with the contents of the present specification, it is to be understood that the application history document, as used herein in the present specification or appended claims, is intended to define the broadest scope of the present specification (whether presently or later in the specification) rather than the broadest scope of the present specification. It is to be understood that the descriptions, definitions and/or uses of terms in the accompanying materials of this specification shall control if they are inconsistent or contrary to the descriptions and/or uses of terms in this specification.

Finally, it should be understood that the embodiments described herein are merely illustrative of the principles of the embodiments of the present disclosure. Other variations are also possible within the scope of the present description. Thus, by way of example, and not limitation, alternative configurations of the embodiments of the specification can be considered consistent with the teachings of the specification. Accordingly, the embodiments of the present description are not limited to only those explicitly described and depicted herein.

Claims

1. A crystal preparation apparatus for preparing a crystal by a liquid phase method, comprising:

the growth chamber is internally provided with at least one plate assembly, wherein the at least one plate assembly comprises through holes, and the through holes of the adjacent plate assemblies are mutually staggered;

the heating assembly is used for heating the growth cavity;

the connecting assembly is used for connecting the seed crystal holder to support the seed crystal; and

and the power assembly is used for driving the connecting assembly to rotate and/or move up and down so as to drive the seed crystal holder to rotate and/or move up and down.

2. The crystal preparation apparatus of claim 1, wherein for at least one of the at least one plate assembly, a ratio of a sum of open areas of the through-holes to an area of an upper surface of the plate assembly is in a range of 30% -80%.

3. The crystal preparation apparatus of claim 1, wherein the density of the through holes decreases from the center to the edge of the plate assembly.

4. The crystal preparation apparatus of claim 1, wherein a ratio of a density of through holes near a center of the plate assembly to a density of through holes near an edge of the plate assembly is in a range of 1:1-20.

5. The crystal preparation apparatus of claim 1, wherein the through-hole has a diameter in the range of 0.1mm-10 mm.

6. The crystal preparation apparatus of claim 1, wherein an upper predetermined extent of the growth chamber sidewall is coated or provided with a shielding ring.

7. The crystal preparation apparatus of claim 1, further comprising a chamber cover and an upper thermal insulation member, wherein a gap between the chamber cover and the upper thermal insulation member is filled with carbon powder.

8. The crystal preparation apparatus of claim 7, wherein the chamber cover comprises a raised structure.

9. The crystal preparation apparatus of claim 1, wherein the growth chamber sidewall has a wall thickness that gradually increases in a direction from the top to the bottom of the growth chamber.