Crystallization manufacturing method

Abstract

One embodiment of this specification provides a crystal manufacturing method comprising: obtaining a first wafer after a first treatment; using the first wafer after the first treatment as a first type crystal and growing it based on a top-seed solution growth method to obtain a preform crystal; performing a second treatment on the preform crystal; using the preform crystal after the second treatment as a second type crystal and growing it based on a physical gas phase transport method to obtain a target crystal.

Description

Technical Field

[0001] This specification relates to the technical field of crystal manufacturing, and particularly to a crystal manufacturing method.

Background Art

[0002] Silicon carbide single crystals have excellent physical and chemical properties, and thus have become an important material for the manufacture of high-frequency and high-power devices. The Physical Vapor Transport (PVT) method is a method for manufacturing semiconductor crystals. However, due to the shortage of high-quality seed crystals, in the process of growing crystals by the PVT method, defects inherent in the seed crystals spread to the epitaxial layer, resulting in a high defect density of the manufactured crystals.

[0003] The Top Seeded Solution Growth (TSSG) method can be used for the manufacture of high-quality silicon carbide crystals because of its low growth temperature and proximity to thermodynamic equilibrium conditions. However, the crystals manufactured by the TSSG method have limited thickness and cannot meet the needs of industrial production.

[0004] Therefore, there is a need to provide a crystal manufacturing method to manufacture large-sized and high-quality crystals.

Summary of the Invention

[0005] One or more embodiments of this specification provide a crystal manufacturing method including obtaining a first wafer after a first treatment, using the first wafer after the first treatment as a first seed crystal, growing a preform crystal based on the top seeded solution growth method, performing a second treatment on the preform crystal, and using the preform crystal after the second treatment as a second seed crystal and growing a target crystal based on the physical vapor transport method.

[0006] One or more embodiments of this specification provide a seed crystal manufacturing method comprising: cutting an off-seed crystal radially to obtain at least two seed crystal wafers; and joining the at least two seed crystal wafers such that the step directions of the joined at least two seed crystal wafers are opposite to obtain a target seed crystal. [Brief explanation of the drawing]

[0007] This specification is further illustrated by exemplary embodiments, which are illustrated in detail by the drawings. These embodiments are not restrictive, and in these embodiments, the same numbers represent the same structure.

[0008] [Figure 1] This is an illustrative flowchart of a crystal manufacturing method according to some examples of this specification. [Figure 2] This is a schematic diagram illustrating some examples of crystal production methods according to the embodiments of this specification. [Figure 3A] This is an illustrative schematic diagram of an example of a first processing being performed on an off-wafer according to some embodiments of this specification. [Figure 3B] Figure 3A is an exemplary top view of the first wafer B after cutting. [Figure 3C] This is an illustrative schematic diagram illustrating some examples of the present specification in which the step direction of the first type crystal and the flow direction of the solution are opposite. [Figure 4A] This is an illustrative cross-sectional view of a second wafer according to some embodiments of this specification. [Figure 4B] This is an illustrative cross-sectional view of a second wafer relating to some other embodiments of this specification. [Figure 4C] This is an illustrative cross-sectional view of a second wafer relating to some other embodiments of this specification. [Figure 5] This is a schematic diagram illustrating the contact angle in some embodiments of this specification. [Modes for carrying out the invention]

[0009] To more clearly illustrate the technical means of the embodiments described herein, the drawings necessary for describing the embodiments are briefly described below. Clearly, the drawings described below are only some examples or embodiments of this specification, and those skilled in the art can apply this specification to other similar situations based on these drawings without any creative work. Unless otherwise stated or evident from the language context, the same numbers in the figures represent the same structure or operation.

[0010] As set forth herein and in the claims, unless the context explicitly indicates otherwise, terms such as “one,” “one,” “one kind,” and / or “the” do not specifically mean singular and may include plural forms. Generally, the terms “includes” and “contains” merely indicate the inclusion of clearly identified steps and elements, and these steps and elements are not an exclusive list; the method or apparatus may also contain other steps or elements.

[0011] This specification uses flowcharts to illustrate the operations performed by the systems according to the embodiments described herein. It should be understood that the operations are not necessarily performed in exact order. Conversely, each step can be performed in reverse order or simultaneously. Furthermore, other operations can be added to these steps, or one or more operations can be removed from these steps.

[0012] Several embodiments of this specification provide a crystal manufacturing method in which a first wafer after a first treatment is used as the first type crystal and grown based on a top-seed solution growth method to obtain a high-quality preform crystal, and a preform crystal after a second treatment is used as the second type crystal and grown based on a physical gas phase transport method to obtain a large, high-quality target crystal.

[0013] Figure 1 is an illustrative flowchart of a crystal manufacturing method according to some embodiments of this specification. In some embodiments, flow 100 may be performed by one or more assemblies. In some embodiments, flow 100 may be performed automatically by a control system. For example, flow 100 may be implemented based on control commands, and the control system may control each assembly based on the control commands to complete each operation of flow 100. In some embodiments, flow 100 may be performed semi-automatically. For example, one or more operations of flow 100 may be performed manually by an operator. In some embodiments, when completing flow 100, one or more additional operations not described may be added and / or one or more operations described herein may be removed. As shown in Figure 1, flow 100 may include the following steps.

[0014] In step 110, the first wafer after the first processing is obtained.

[0015] In some embodiments, the first process may include, but is not limited to, grinding and / or polishing of the first wafer. In some embodiments, grinding may refer to processing the surface of the first wafer by relative motion between a grinding tool and the first wafer at a predetermined pressure. In some embodiments, the surface of the grinding tool may be coated with abrasive particles or embedded with abrasive particles. In some embodiments, polishing may refer to reducing the roughness of the surface and making the surface flat by processing the surface of the first wafer using an abrasive medium. In some embodiments, the abrasive medium may be abrasive powder.

[0016] In some embodiments, the first treatment may further include cutting, etc., before grinding and / or polishing the first wafer. In some embodiments, the first wafer may be obtained by growing by the PVT method.

[0017] In some embodiments, the first wafer may include, but is not limited to, a silicon carbide wafer, an aluminum nitride wafer, and the like.

[0018] Please understand that because the defect density of the first wafer manufactured by the PVT method is high, it is necessary to perform the first treatment on the first wafer to make the surface of the resulting first wafer flatter and reduce the defect density of the first wafer.

[0019] In some embodiments, the material of the seed crystal holder may include, but is not limited to, graphite. When growing a preform crystal using the first wafer after the first treatment as the first seed crystal based on the top-seeded solution growth method, the thickness of the first wafer after the first treatment needs to be greater than the first thickness threshold in order to avoid a decrease in the quality of the manufactured preform crystal due to the solution reaching the back surface of the first seed crystal due to the action of surface tension and reacting with the seed crystal holder during the crystal growth process. However, if the thickness of the first seed crystal is too large, the weight of the first seed crystal will be too large during the process of manufacturing the preform crystal by the TSSG method, which may cause detachment due to adhesion strength issues between the first seed crystal and the seed crystal holder. Therefore, the thickness of the first wafer after the first treatment needs to be less than the second thickness threshold. The first and second thickness thresholds may be empirical values ​​or preset values.

[0020] In some embodiments, the thickness of the first wafer after the first treatment may be 0.35 mm to 10 mm. In some embodiments, the thickness of the first wafer after the first treatment may be 0.5 mm to 9.5 mm. In some embodiments, the thickness of the first wafer after the first treatment may be 1 mm to 9 mm. In some embodiments, the thickness of the first wafer after the first treatment may be 1.5 mm to 8.5 mm. In some embodiments, the thickness of the first wafer after the first treatment may be 2 mm to 8 mm. In some embodiments, the thickness of the first wafer after the first treatment may be 2.5 mm to 7.5 mm. In some embodiments, the thickness of the first wafer after the first treatment may be 3 mm to 7 mm. In some embodiments, the thickness of the first wafer after the first treatment may be 3.5 mm to 6.5 mm. In some embodiments, the thickness of the first wafer after the first treatment may be 4 mm to 6 mm. In some embodiments, the thickness of the first wafer after the first treatment may be 4.5 mm to 5.5 mm.

[0021] In some embodiments of the present specification, by controlling the thickness of the first wafer after the first treatment, in the process of manufacturing a preform crystal by the TSSG method using it as a first type crystal, not only can a certain thickness required for re-dissolving the first type crystal be ensured, but also it is possible to avoid the solution reaching the back surface of the first type crystal and reacting with the seed crystal holder, and it can be guaranteed that the first type crystal does not fall off from the seed crystal holder due to excessive weight.

[0022] When manufacturing a preform crystal by the TSSG method using the first wafer after the first treatment as the first type of crystal, since the solution exhibits a flow direction that diffuses from the center to the periphery under the action of centrifugal force, if the first wafer is an off-wafer, a part of the step direction of the off-wafer is the same as the flow direction of the solution, and thus there are many defects in the crystal grown in this part. In some embodiments, when the first wafer is an off-wafer, the first treatment may further include cutting the first wafer in the radial direction to obtain at least two cut first wafers, and joining the at least two cut first wafers such that the step directions of the at least two joined cut first wafers are opposite. In this way, when manufacturing a preform crystal by the TSSG method using the at least two joined cut first wafers as the first type of crystal, it is possible to realize that the flow direction of the solution is opposite to the step direction of the first type of crystal.

[0023] Figure 2 is an exemplary schematic diagram of a crystal manufacturing method according to some embodiments of the present specification. Figure 3A is an exemplary schematic diagram of performing the first treatment on an off-wafer according to some embodiments of the present specification. Figure 3B is an exemplary top view of the first wafer B after cutting in Figure 3A. Figure 3C is an exemplary schematic diagram of a case where the step direction of the first type of crystal is opposite to the flow direction of the solution according to some embodiments of the present specification.

[0024] In some embodiments, as shown in Figure 3A, if the first wafer is an off-wafer 310, the off-wafer 310 can be cut radially to obtain two cut first wafers 320. In some embodiments, radial cutting may refer to cutting along the diametrical direction or a direction perpendicular to the axis. As shown in Figure 2, radial cutting may be indicated by double arrows ab. An off-wafer is a wafer in crystallography where the c-axis (longest axis) is deflected by a predetermined angle to the crystal direction. In some embodiments, the off-wafer may be obtained by machining the wafer (e.g., cutting or bevel cutting). Due to the limitations of machining, it should be understood that the step direction of the off-wafer is always along a single direction. As shown in Figure 3A, the step directions of the off-wafer 310 coincide and both point to one side. Therefore, at least two cut first wafers 320 need to be joined to ensure that the direction of solution flow and all step directions of the first type crystal are opposite.

[0025] At least two cut first wafers 320 may be joined by multiple methods such that the step directions of the two joined cut first wafers 320 are opposite. For example, when joining two cut first wafers 320, one of the cut first wafers (e.g., cut first wafer A321 shown in Figure 3A) may be held still, and the other cut first wafer (e.g., cut first wafer B322 shown in Figure 3A) may be mirrored at least once, and the mirrored cut first wafer B322 and the still-held cut first wafer A321 may be joined so that the step directions of the two joined cut first wafers are opposite. The mirroring may include rotating 180° around a certain axis (e.g., a flat, vertical, or horizontal central axis of the cut first wafer B).

[0026] In some embodiments, the first process may further include rotating and / or inverting at least one of the at least two cut first wafers 320. The rotating and / or inverting process may include rotating by a predetermined angle around a certain axis (e.g., a flat, vertical, or horizontal central axis of the cut first wafer) as the axis of rotation. As just one example, if the first wafer is an off-wafer 310, as shown in Figure 3A, the off-wafer 310 can be cut radially to obtain cut first wafers A321 and B322. The first wafer A321 after cutting is held in place, and the first wafer B322 after cutting is rotated 180° clockwise (in the direction indicated by arrow b in Figure 3A) around its flat (the flat indicated by m in Figure 3B) as the axis of rotation to obtain the first wafer B322-1 after cutting shown in Figure 3A. Next, the first wafer B322-1 after cutting is rotated 180° around its flat (the flat indicated by n in Figure 3A) as the axis of rotation to obtain the first wafer B322-2 after cutting. Then, the first wafer B322-2 after cutting and the first wafer A321 after cutting are joined together to obtain two joined first wafers after cutting (also called the first type crystal 330) as shown in Figure 3A. As shown in Figures 3A and 3C, of ​​the two bonded cut first wafers (also called the first type crystal 330), the step direction of the cut first wafer A321 and the step direction of the cut first wafer B322 are opposite. As shown in Figure 3C, when a preform crystal is manufactured by the TSSG method using the two bonded cut first wafers as the first type crystal 330, the step direction and the solution flow direction are opposite (it may be understood that step B obstructs the solution flow or the solution flow collides with step B). Step B may be understood as a cut parallel to the axis of the first type crystal 330.

[0027] In the embodiments described herein, the shape of the off-wafer 310 is not limited and may be, for example, a rectangular parallelepiped, a cube, a cylinder, etc. For example, as shown in Figures 3A and 3B, the off-wafer 310 may be a rectangular parallelepiped. In some embodiments, the cross-section of the off-wafer 310 may be a regular or irregular shape such as a polygon (e.g., rectangle, square), circle, or ellipse. In some embodiments, the shape may be changed by cutting the flats of at least two joined cut first wafers. For example, a cylindrical seed crystal can be obtained by cutting the rectangular parallelepiped first seed crystal 330 shown in Figure 3A.

[0028] In some embodiments, when the first wafer (also referred to here as the off-wafer 310) is cylindrical, two cylindrical first wafers with opposite step directions can be cut radially, and then the two cut first wafers with opposite step directions can be joined to obtain two joined cut first wafers with opposite step directions, the two joined cut first wafers being cylindrical.

[0029] In some embodiments of this specification, when a first wafer is cut radially, and at least two cut first wafers are joined together such that the step directions of the two joined first wafers are opposite, and a preform crystal is grown using this as the first type crystal based on the TSSG method, the step direction of the first type crystal and the flow direction of the solution are opposite, so the aggregation behavior of the steps can be significantly suppressed, which is advantageous in reducing micro and macro defects, improving the quality of the manufactured preform crystal and making the overall shape of the crystal flatter and smoother.

[0030] Since the first wafer has undergone radial cutting and bonding, when at least two bonded cut first wafers are directly bonded onto a seed crystal holder and a preform crystal is manufactured using this as the first seed crystal based on the TSSG method, it should be understood that during the crystal growth process, the solution rises along the bonding seam of the at least two bonded cut first wafers due to capillary force, comes into contact with the seed crystal holder and reacts, thereby degrading the quality of the manufactured preform crystal. In some embodiments, to avoid the above situation, at least two cut first wafers can be bonded by bonding them to a second wafer. As just one example, as shown in Figures 3A and 3C, after bonding cut first wafer A321 and cut first wafer B322, two bonded cut first wafers (also called the first seed crystal 330) are obtained, and one side of the second wafer 400 may be bonded to the first seed crystal 330, and the other side of the second wafer 400 may be bonded to the seed crystal holder A.

[0031] As shown in Figures 3A and 3C, the second wafer 400 is positioned between the first seed crystal 330 and the seed crystal holder A and can be used to bond the first seed crystal 330 and the seed crystal holder A. In some embodiments, the second wafer 400 may include an equiaxial wafer or an off-wafer. In some embodiments, the material of the second wafer 400 may be the same as or different from that of the first seed crystal 330. In some embodiments, the shape of the second wafer 400 may be the same as or different from that of the first seed crystal 330.

[0032] The at least two cut first wafers, bonded together by a thermal bonding method, may be attached to the second wafer. Bonding of the at least two cut first wafers and the second wafer may also be achieved by other methods, such as bonding with an adhesive. The bonding method between the second wafer and the seed crystal holder may be the same as, or different from, the bonding method between the at least two cut first wafers (also called the first seed crystals) and the second wafer.

[0033] In some embodiments of this specification, at least two bonded cut first wafers (also called first seed crystals) are bonded to one side of a second wafer, and then the other side of the second wafer is bonded to a seed crystal holder. This prevents the solution from directly contacting and reacting with the seed crystal holder through the bonded seam during the process of manufacturing preform crystals using the first seed crystal based on the TSSG method, which is advantageous for improving the quality of the manufactured preform crystals.

[0034] In some embodiments, a notch may be provided at a predetermined height on the second wafer to further reduce the amount of solution reaching the surface of the seed crystal holder. In some embodiments, the predetermined height may refer to the distance between the lowest edge of the notch on the second wafer and the bottom surface of the second wafer. The predetermined height may be a preset value or a default value. In some embodiments, the notch may include multiple structures, such as annular structures. In some embodiments, the longitudinal cross-section of the notch may be any shape, such as a regular or irregular shape, such as a polygon or a circle. In some embodiments, the depth of the notch may refer to the distance between the furthest edge of the notch and the side surface of the second wafer. In some embodiments, the inclination of the notch may refer to the angle between the inclined edge of the notch and the horizontal plane.

[0035] As shown in Figure 4A, an annular notch 410 with a rectangular longitudinal cross-section is provided at a predetermined height (indicated as h1 in Figure 4A) of the second wafer 400. The depth of the notch 410 (which may be understood as the length of the rectangle) may be represented by L1 in Figure 4A. As shown in Figure 4B, an annular notch 410 with a parallelogram longitudinal cross-section is provided at a predetermined height (indicated as h2 in Figure 4B) of the second wafer 400. The depth of the notch 410 may be represented by L2 in Figure 4B, and the inclination of the notch 410 is α. As shown in Figure 4C, an annular notch 410 with a semicircular longitudinal cross-section is provided at a predetermined height (indicated as h3 in Figure 4C) of the second wafer 400. The depth of the notch 410 (which may be understood as the radius of the semicircle) may be represented by L3 in Figure 4C.

[0036] When producing a preform crystal based on the TSSG method using at least two bonded cut first wafers as the first type crystal, in some embodiments, the first process may further include performing a third process on the at least two bonded cut first wafers to form a contact angle at the edges of the at least two cut first wafers adjacent to the bonded seam, so that the solution can penetrate the entire bonded seam better due to the action of surface tension, crystal growth can be carried out at the bonded seam, and the entire bonded seam can be closed.

[0037] The third process may include performing a cutting process on at least two edges (e.g., growth edges) adjacent to the joint of the cut first wafer to form a contact angle. As just one example, as shown in Figure 5, the edges (e.g., growth edges) adjacent to the joint of the cut first wafer A321 and the cut first wafer B322 are each cut to obtain the cut first wafer A321-1 and the cut first wafer B322-3 after the third process, and then joining them to form the first type crystal 330. As shown in Figure 5, a contact angle θ may be formed at the joint of the first type crystal 330.

[0038] It should be understood that the contact angle is used in the process of growing crystals using the TSSG method with type I crystals to allow the solution to penetrate the joint better and close the joint for growth. The contact angle can have various structures, such as cylinders, cones, or polyhedra. Therefore, the longitudinal section of the contact angle may be a polygon, a triangle (shown in Figure 5), etc. In some embodiments, the longitudinal section of the contact angle may be any other shape that can increase the capillary force of the solution at the joint. As an example, as shown in Figure 5, the joint may be a cone with its base circle close to one end of the step. The radius of the joint may be understood as the radius of the base circle of the cone, and the contact angle may be understood as the apex angle of the cone. The length to which the solution has penetrated the joint can be calculated by the formula H = 2γcosθ / ρgr. In the formula, H is the length of the joint (i.e., the thickness of the first wafer after the first processing), γ is the surface tension of the liquid (which may be understood as the molten raw material) in the TSSG method, ρ is the density of the liquid, g is the acceleration due to gravity, r is the radius of the joint, and θ is the contact angle between the liquid and the seed crystal (e.g., the first seed crystal).

[0039] In some embodiments, if the contact angle is too large, cracks will form in the grown crystal. Therefore, the contact angle must be smaller than a predetermined threshold. In some embodiments, the contact angle θ may be greater than 0° and less than 20°. In some embodiments, the contact angle θ may be greater than 2° and less than 18°. In some embodiments, the contact angle θ may be greater than 4° and less than 16°. In some embodiments, the contact angle θ may be greater than 6° and less than 14°. In some embodiments, the contact angle θ may be greater than 8° and less than 12°. In some embodiments, the contact angle θ may be greater than 9° and less than 10°.

[0040] In some embodiments of this specification, performing a third treatment on at least two cut first wafers to form a contact angle at the edges adjacent to the joint of the at least two bonded cut first wafers is advantageous in enhancing the capillary force of the solution, allowing the solution to penetrate the joint better and close the joint by crystal growth.

[0041] In step 120, the first wafer after the first processing is used as the first type crystal, and a preform crystal is obtained by growing it based on the top seed solution growth method.

[0042] The top-seed solution growth method refers to a method of producing crystals by dissolving the raw material for crystal production (e.g., silicon carbide powder) in a low-melting-point flux at high temperature to form a uniform saturated solution, then gradually lowering the temperature to form a supersaturated solution, and finally precipitating the crystal onto the seed crystal.

[0043] A preform crystal refers to an intermediate crystal produced by the TSSG method.

[0044] After bonding the first seed crystal to one side of the second wafer, the other side of the second wafer is bonded to a seed crystal holder, and a preform crystal is obtained by growing it using a top-seeding solution growth method. As just one example, as shown in Figure 2, the first wafer 210 after the first treatment is used as the first seed crystal, and a crystal growth layer 220 having a predetermined thickness is manufactured based on the TSSG method. The first wafer 210 and the crystal growth layer 220 after the first treatment may also be called a preform crystal.

[0045] When obtaining preform crystals by growing them from a type I crystal using the top-seeded solution growth method, it should be understood that, due to limitations of the TSSG method, if the thickness of the produced crystal growth layer is too large, a large number of macrodefects (e.g., solvent inclusions) will occur in the crystal growth layer. Therefore, the thickness of the crystal growth layer produced by the TSSG method must satisfy certain conditions. In some embodiments, during the growth process of the crystal growth layer of the preform crystal, it is necessary to control the thickness of the crystal growth layer 220 grown using the top-seeded solution growth method to within the range of 1 mm to 1.5 mm. In some embodiments, during the growth process of the preform crystal, the thickness of the crystal growth layer 220 grown using the top-seeded solution growth method may be controlled to within the range of 1.1 mm to 1.4 mm. In some embodiments, during the growth process of the preform crystal, the thickness of the crystal growth layer 220 grown using the top-seeded solution growth method may be controlled to within the range of 1.2 mm to 1.3 mm.

[0046] In some embodiments of this specification, controlling the thickness of the crystal growth layer produced by the TSSG method not only reduces various defect problems caused by excessive growth thickness of the produced preform crystal, but also ensures that the preform crystal has a predetermined thickness, thus allowing for subsequent second processing of the preform crystal.

[0047] In step 130, the preform crystal undergoes a second treatment.

[0048] The second treatment may include, but is not limited to, grinding and / or polishing of the preform crystal or its crystal growth layer.

[0049] It should be understood that a second treatment is necessary for the preform crystal or its crystal growth layer because a certain amount of solvent and / or crystal particles adhere to the surface of the crystal growth layer of the preform crystal manufactured by the TSSG method. In some embodiments, the second treatment can be performed on the preform crystal or its crystal growth layer in various ways. As just one example, as shown in Figure 2, the surface of the crystal growth layer 220 can be processed by relative motion between a grinding tool and the crystal growth layer 220 at a predetermined pressure, thereby improving its surface smoothness and flatness, reducing surface defects, and obtaining the crystal growth layer 230 after the second treatment. In some embodiments, the method of the second treatment may be the same as or different from the method of the first treatment. As shown in Figure 2, the first wafer 210 after the first treatment and the crystal growth layer 230 after the second treatment may be called the preform crystal after the second treatment.

[0050] To produce high-quality target crystals, when the preform crystal after the second treatment is used as the second type crystal, it is necessary to ensure that the surface of the second type crystal is sufficiently smooth and flat and as free of defects as possible. In some embodiments, the surface roughness of the second type crystal may be 0.2 nm or less. In some embodiments, the surface roughness of the second type crystal may be 0.15 nm or less. In some embodiments, the surface roughness of the second type crystal may be 0.1 nm or less. In some embodiments, the surface roughness of the second type crystal may be 0.05 nm or less.

[0051] In some embodiments of this specification, when the preform crystal is used as the second type crystal in the PVT method, a second treatment is performed on the preform crystal so that the surface roughness is 0.2 nm or less. This ensures that the surface of the second type crystal is smooth and flat, improving the quality of the second type crystal, which is advantageous for further improving the quality of the target crystal produced by the PVT method thereafter.

[0052] In step 140, the preform crystal after the second treatment is designated as the second type crystal and grown based on the physical gas phase transport method to obtain the target crystal.

[0053] Physical gas-phase transport refers to a method in which a material decomposes and sublimes under high-temperature conditions to become gaseous components, which are then transported to a seed crystal in a low-temperature region under the driving of an axial temperature gradient, and the crystal is deposited and grown on the surface of the seed crystal.

[0054] The target crystal can be obtained by growing it using a physical vapor transport method based on a Type II crystal. As a simple example, as shown in Figure 2, the first wafer 210 after the first treatment and the crystal growth layer 230 after the second treatment can be collectively referred to as a Type II crystal (which may also be called a preform crystal after the second treatment), and the target crystal growth layer 240 can be obtained by manufacturing it using the PVT method based on the Type II crystal. The target crystal may include the first wafer 210 after the first treatment, the crystal growth layer 230 after the second treatment, and the target crystal growth layer 240.

[0055] In some embodiments of this specification, high-quality preform crystals are produced by the TSSG method, subjected to a second treatment to obtain high-quality type II crystals, and then the target crystals are produced by the PVT method using these preform crystals. This not only allows for the production of large target crystals but also ensures the high quality of the target crystals and reduces micro and macro defects within them.

[0056] The above description of Flow 100 is for illustrative and illustrative purposes only and does not limit the scope of this specification. Those skilled in the art can make various modifications and changes to Flow 100 under the guidance of this specification. However, these modifications and changes remain within the scope of this specification.

[0057] Embodiments herein further provide a seed crystal manufacturing method comprising: radially cutting an off-seed crystal to obtain at least two seed crystal wafers; and bonding the at least two seed crystal wafers such that the step directions of the bonded at least two seed crystal wafers are opposite to obtain a target seed crystal. In some embodiments, the method may further include rotating and / or inverting at least one of the at least two seed crystal wafers. In embodiments herein, the off-seed crystal and off-wafer may be used interchangeably. In some embodiments, bonding may include bonding at least two seed crystal wafers by bonding them to a wafer. For descriptions of radial cutting and bonding, refer to the relevant descriptions in other parts of this specification (e.g., Figures 3A-3C), which are omitted here.

[0058] In some embodiments, a notch may be provided at a predetermined height on the wafer. For a description of the notch, please refer to the relevant descriptions in other parts of this specification (e.g., Figures 4A to 4C), and a description is omitted here.

[0059] In some embodiments, the method further includes processing the bonded at least two seed crystal wafers to form a contact angle at the edges adjacent to the bonded seam of the at least two seed crystal wafers. For a description of the contact angle, refer to the relevant description in other parts of this specification (e.g., Figure 5), which is omitted here.

[0060] In some embodiments of this specification, an off-seed crystal is cut radially, and at least two seed crystal wafers obtained by cutting are joined together such that the step directions of the two joined seed crystal wafers are opposite to each other to obtain a target seed crystal. When a crystal is grown using this target seed crystal based on the TSSG method, the step direction of the target seed crystal and the flow direction of the solution are opposite, which significantly suppresses the aggregation behavior of the steps, is advantageous in reducing micro and macro defects, improves the quality of the manufactured crystal, and makes the overall shape of the crystal flatter and smoother.

[0061] Having explained the basic concepts above, it will be clear to those skilled in the art that the above detailed disclosures are merely illustrative and do not limit this specification. Although not explicitly described herein, those skilled in the art can make various changes, improvements, and modifications to this specification. These changes, improvements, and modifications, being proposed herein, remain within the spirit and scope of the exemplary embodiments herein.

[0062] Furthermore, certain terms are used herein to describe the embodiments. For example, “one embodiment,” “one embodiment,” and / or “several embodiments” mean certain features, structures, or properties relating to at least one embodiment of this specification. Therefore, it should be emphasized and understood that two or more references to “one embodiment,” “one embodiment,” or “one alternative embodiment” in various parts of this specification do not necessarily refer to the same embodiment. Also, certain features, structures, or properties in one or more embodiments of this specification may be combined appropriately.

[0063] Furthermore, unless explicitly stated in the claims, the enumerated order, use of alphanumeric characters, or use of other names of the processing elements or sequences described herein is not intended to limit the order of the flows and methods herein. While various examples illustrate what are currently considered useful embodiments of the invention in the above disclosure, such details are for illustrative purposes only, and it should be understood that the appended claims are not limited to the disclosed embodiments, but rather intended to cover all modifications and equivalent combinations within the spirit and scope of the embodiments herein. For example, the system assembly described above may be implemented by hardware devices, but may also be implemented by software-only solutions, such as installing the described system on an existing server or mobile device.

[0064] Similarly, in order to simplify the expressions disclosed herein and to aid in understanding one or more embodiments of the invention, various features may be combined into a single embodiment, drawing, or description thereof in the preceding description of embodiments herein. However, such a method of disclosure does not mean that the features required for the subject matter herein are greater than the features described in the claims. In fact, the features of an embodiment may be fewer than all the features of a single embodiment disclosed above.

[0065] In some embodiments, numbers are used to describe the number of components and attributes, and it should be understood that in some examples, these numbers describing such embodiments are modified by the modifiers “about,” “approximately,” or “generally.” Unless otherwise specified, “about,” “approximately,” or “generally” indicates that the above numbers are allowed to vary by ±20%. Therefore, in some embodiments, the numerical parameters used in the specification and claims are all approximations that may vary depending on the characteristics required for the individual embodiment. In some embodiments, the numerical parameters should be treated with a specified number of significant figures and the usual place-keep method. In some embodiments of this specification, the numerical ranges and parameters used to determine their ranges are approximations, but in specific embodiments, such numbers are set as precisely as possible.

[0066] All patents, patent applications, published patent gazettes, and other materials such as articles, books, specifications, publications, and documents referenced herein are incorporated herein by reference in their entirety, with the exception of any prosecution history documents that are inconsistent with or contradict the content of this specification, and any documents that may have a limited effect on the broadest scope of the claims herein (currently or later relating to this specification). In the event of any inconsistency between the use of explanations, definitions, and / or terms in the accompanying materials of this specification and the content herein, the use of explanations, definitions, and / or terms herein shall prevail.

[0067] Finally, it should be understood that the examples described herein are merely illustrative of the principles of the examples herein. Other modifications may also be within the scope of this specification. Therefore, alternative configurations of the examples herein may be considered consistent with the teachings herein, not as limitations but as examples. Thus, the examples herein are not limited to those explicitly introduced and described herein. [Explanation of Symbols]

[0068] 210 First wafer after first processing 220 Crystal growth layer 230 Crystal growth layer after the second treatment 240 Target crystal growth layer 310 Off-wafer 320 First wafer after cutting 321, 321-1 First wafer A after cutting 322, 322-1, 322-2, 322-3 First wafer B after cutting 330 1st seed crystal 400 Second wafer 410 Notches

Claims

1. To obtain a first wafer after the first processing, The first wafer after the first processing is used as the first type crystal, and a preform crystal is obtained by growing it based on the top seed solution growth method. The second treatment is performed on the aforementioned preform crystal, A crystal manufacturing method characterized by comprising: using the preform crystal after the second treatment as a type 2 crystal and growing it based on a physical gas phase transport method to obtain a target crystal.

2. The crystal manufacturing method according to claim 1, characterized in that the thickness of the first wafer after the first processing is 0.35 mm to 10 mm.

3. The crystal manufacturing method according to claim 1, further comprising controlling the thickness of the crystal growth layer grown based on the top seed solution growth method to within a range of 1 mm to 1.5 mm during the growth process of the preform crystal.

4. The crystal manufacturing method according to claim 1, characterized in that the surface roughness of the second type of crystal is 0.2 nm or less.

5. The crystal manufacturing method according to claim 1, characterized in that the first treatment and / or the second treatment includes grinding and / or polishing.

6. If the first wafer is off-wafer, the first process is performed. The first wafer is cut radially to obtain at least two cut first wafers, The crystal manufacturing method according to claim 1, further comprising joining the at least two cut first wafers such that the step directions of the joined at least two cut first wafers are opposite.

7. The crystal manufacturing method according to claim 6, further comprising performing a rotation and / or inversion process on at least one of the at least two cut first wafers.

8. The crystal manufacturing method according to claim 6, characterized in that joining the at least two cut first wafers includes joining the at least two cut first wafers by bonding them to a second wafer.

9. The crystal manufacturing method according to claim 8, characterized in that a notch is provided at a predetermined height position of the second wafer.

10. The first process is, The crystal manufacturing method according to claim 6, further comprising performing a third process on the joined at least two cut first wafers so as to form a contact angle at the edges adjacent to the joint of the at least two cut first wafers.

11. The off-seed crystal is cut radially to obtain at least two seed crystal wafers, A method for manufacturing a seed crystal, characterized by comprising: joining at least two seed crystal wafers such that the step directions of the joined at least two seed crystal wafers are opposite to each other, in order to obtain a target seed crystal.

12. The seed crystal manufacturing method according to claim 11, further comprising performing a rotation and / or inversion process on at least one of the at least two seed crystal wafers.

13. The seed crystal manufacturing method according to claim 11, characterized in that joining the at least two seed crystal wafers includes joining the at least two seed crystal wafers by bonding them to a wafer.

14. The seed crystal manufacturing method according to claim 13, characterized in that a notch is provided at a predetermined height position on the wafer.

15. The seed crystal manufacturing method according to claim 11, further comprising performing a process on the joined at least two seed crystal wafers so as to form a contact angle at the edges adjacent to the joint of the at least two seed crystal wafers.

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