Seed crystal alignment method for growing single crystal by edge-defined film-fed growth method and single crystal growth method

Abstract

The invention discloses a seed crystal alignment method for growing a single crystal by an edge-defined film-fed crystal growth method and a single crystal growth method, and belongs to the technical field of single crystal growth by the edge-defined film-fed crystal growth method. The method comprises the following steps: firstly descending a seed crystal rod until the lower end of a seed crystal is positioned near the upper part of the surface of a mold, then attaching a strip-shaped sheet below the alignment surface of the seed crystal, rotating the seed crystal to enable the strip-shaped sheet to be parallel to or form a required angle with the long edge of the mold, taking down the strip-shaped sheet after ensuring angle calibration, and finally adjusting the position of the seed crystal in the horizontal direction. And the seed crystal is positioned at the center of the mold to finish seed crystal alignment. According to the invention, the alignment surface of the seed crystal is determined, and the alignment surface is extended by using the adhesive strip-shaped sheet, so that a more intuitive and easier-to-operate calibration reference can be provided on the macroscopic level. And by utilizing the unique design of the amplification surface of the seed crystal alignment surface, a simple and feasible way is provided for alignment and angle calibration of the seed crystal alignment surface and the mold. By adopting the method, the accuracy degree of seed crystal alignment can be greatly improved, the accuracy rate of crystal growth surface types is improved, meanwhile, the material drawing range of crystal processing is increased, and the utilization rate of crystal blanks is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of single crystal growth by the edge-defined film-fed growth (EFG) method, and particularly to a seed crystal alignment method and a single crystal growth method for growing single crystals by the EFG method. Background Art

[0002] The EFG method is one of the methods for preparing single crystal materials from a melt, that is, the edge-defined film-fed growth technology. This method is usually used for shaping and growing single crystal materials. The growth process is that the raw materials in the crucible are melted under the heat transfer of the induction-heated crucible wall. The melt climbs to the top of the mold along the mold gap at the bottom of the mold under capillary action. A seed crystal is brought into contact with the melt at the top of the mold. By adjusting the temperature and the pulling speed of the seed crystal, as the seed crystal is pulled up, crystallization occurs continuously along the direction of the seed crystal. At the same time, the upper edge of the mold defines the shape of the crystal crystallization. Finally, after processes such as necking down, shoulder formation, equal diameter, pulling off, and cooling, a crystal with a shape corresponding to the mold is grown. Therefore, during the process of growing a single crystal by the EFG method, the position, direction, and angle (the angle between the seed crystal and the mold) of the seed crystal placement are particularly important.

[0003] During the process of growing a crystal with a specific plane by the EFG method, such as the 100 plane of a gallium oxide single crystal, it is usually necessary to ensure that the 100 plane of the seed crystal is parallel to the long side of the mold. At the same time, since the general thermal field is an axisymmetric structure, the seed crystal needs to be at the center position of the mold. However, currently, when loading the furnace, there is a lack of a simple and accurate method to calibrate the direction of the seed crystal. Usually, it is judged by the naked eye whether the direction of the seed crystal is accurate. Since the size of the seed crystal is very small, the cross-sectional size (the vertical plane in the pulling direction) of the general seed crystal is about 5 mm, and the color is very light or transparent. At the same time, the mold is made of precious metal, and the surface of the mold will be polished before growth, so the reflection on the surface of the mold also brings interference to the alignment of the seed crystal. During the crystal growth process, the placement angle of the seed crystal plays a key role. Atoms or molecules in the growth medium will arrange and grow according to the crystal structure and orientation on the surface of the seed crystal, so that the grown crystal has the same or similar crystal orientation as the seed crystal. Therefore, when the placement angle of the seed crystal is deviated, as Figure 1 shown, if the angle between the 100 plane of the seed crystal 1 and the long side of the mold 3 is α, the crystal surface type of the grown crystal will also deviate from the ideal state. Usually, the surface of the mold is rectangular. When the ratio of the length to the width is large and the large plane direction of the crystal is shifted, the grown crystal is often difficult to process into a wafer with a required size, ultimately resulting in material waste.

[0004] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0005] In view of the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a seed crystal alignment method and a single crystal growth method for growing single crystals by the guiding mode method, aiming to solve the problem that there is a lack of an effective method to align the seed crystal, resulting in inaccurate crystal surface shape or crystal size not meeting the requirements of the grown crystal.

[0006] The technical solution of the present invention is as follows:

[0007] In the first aspect of the present invention, a seed crystal alignment method for growing single crystals by the guiding mode method is provided, which includes the steps of:

[0008] Step A: Lower the seed crystal rod;

[0009] Step B: Determine the alignment plane of the seed crystal, and attach a strip-shaped thin sheet below the alignment plane of the seed crystal;

[0010] Step C: Rotate the seed crystal to make the strip-shaped thin sheet parallel to the long side of the mold or at a required angle;

[0011] Step D: After Step C is completed, remove the strip-shaped thin sheet;

[0012] Step E: Finally, adjust the position of the seed crystal in the horizontal direction to make the seed crystal at the center of the mold, and complete the alignment of the seed crystal.

[0013] Optionally, in Step A, lower the seed crystal rod until the lower end of the seed crystal is 3 - 5 mm above the surface of the mold.

[0014] Optionally, in Step B, apply an adhesive to the middle position of the strip-shaped thin sheet, and attach the strip-shaped thin sheet below the alignment plane of the seed crystal.

[0015] Optionally, in Step B, the material of the strip-shaped thin sheet is gallium oxide single crystal.

[0016] Optionally, in Step D, after the step of removing the strip-shaped thin sheet, it further includes the step of wiping the bonding part between the seed crystal and the strip-shaped thin sheet clean with alcohol.

[0017] Optionally, the single crystal is a gallium oxide single crystal.

[0018] In the second aspect of the present invention, a growth method for growing single crystals by the guiding mode method is provided, which includes the steps of:

[0019] First, perform seed crystal alignment by using the seed crystal alignment method for growing single crystals by the guiding mode method of the present invention;

[0020] Then, keep the angle and the position in the horizontal direction of the seed crystal unchanged, lower the seed crystal rod, and after the seed crystal contacts the melt on the surface of the mold, perform seeding, necking, shoulder release, and equal diameter growth in sequence to obtain the required single crystal.

[0021] Optionally, the single crystal is a gallium oxide single crystal.

[0022] Optionally, the surface type of the gallium oxide single crystal is the 100 plane.

[0023] Optionally, the material of the mold is iridium.

[0024] Beneficial effects: In the present invention, first, lower the seed crystal rod until the lower end of the seed crystal is near the upper side of the mold surface, then attach the strip-shaped thin sheet below the opposite plane of the seed crystal, then rotate the seed crystal rod to make the strip-shaped thin sheet parallel to the long side of the mold or at the required angle. After ensuring the angle calibration, remove the strip-shaped thin sheet, and finally adjust the position of the seed crystal in the horizontal direction (i.e., the long side direction of the mold) to make it at the exact center of the mold to complete the alignment of the seed crystal. By determining the opposite plane of the seed crystal and using the adhesive strip-shaped thin sheet to extend it, the present invention can provide a more intuitive and easier-to-operate calibration reference at the macroscopic level. Using the unique design of the enlarged plane of the opposite plane of the seed crystal provides a simple and feasible way for the alignment and angle calibration of the opposite plane of the seed crystal and the mold. By adopting the above seed crystal alignment method, the present invention can greatly improve the accuracy of seed crystal alignment, reduce the error during the alignment of small seed crystals, effectively reduce the probability of crystal growth deviation, improve the accuracy of the crystal growth surface type, increase the material selection range of crystal processing, and improve the utilization rate of crystal blanks. In addition, the present invention can shorten the furnace loading time and improve the growth efficiency during the implementation process. Description of the Drawings

[0025] Figure 1 It is a schematic diagram of the projection of the seed crystal cross-section on the mold surface, where (a) is when the seed crystal is aligned and (b) is when the seed crystal has a deviation of α.

[0026] Figure 2 It is a schematic diagram of a seed crystal alignment method for growing a single crystal by the guiding mold method provided by an embodiment of the present invention, where 1 is the seed crystal, 2 is the strip-shaped thin sheet adhered to the opposite plane of the seed crystal, and 3 is the mold.

[0027] Figure 3 It is a schematic flowchart of a seed crystal alignment method for growing a single crystal by the guiding mold method provided by another embodiment of the present invention. Detailed Embodiments

[0028] The present invention provides a seed crystal alignment method and a single crystal growth method for growing a single crystal by the guiding mold method. To make the purpose, technical solution and effects of the present invention clearer and more definite, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] Combined with Figure 2 As shown, an embodiment of the present invention provides a seed crystal alignment method for growing a single crystal by the guiding mold method, which includes the steps:

[0030] Step A: Lower the seed crystal rod.

[0031] Step B: Determine the opposite plane of the seed crystal 1, and attach the strip-shaped thin sheet 2 below the opposite plane of the seed crystal 1.

[0032] Step C: Rotate the seed crystal 1 to make the strip-shaped thin sheet 2 parallel to the long side of the mold 3 or at a required angle ( Figure 2 shown as parallel in

[0033] Step D: After Step C is completed, remove the strip-shaped thin sheet 2.

[0034] Step E: Finally, adjust the position of the seed crystal 1 in the horizontal direction so that the seed crystal 1 is at the exact center of the mold 3, completing the alignment of the seed crystal.

[0035] In this embodiment, first lower the seed crystal rod until the lower end of the seed crystal is near the surface of the mold, then attach the strip-shaped thin sheet below the opposite plane of the seed crystal (i.e., the large plane required for single crystal growth), then rotate the seed crystal to make the strip-shaped thin sheet parallel to the long side of the mold or at a required angle. After ensuring the angle calibration, remove the strip-shaped thin sheet, and finally adjust the position of the seed crystal in the horizontal direction (i.e., the long side direction of the mold) so that it is at the exact center of the mold, completing the alignment of the seed crystal. In this embodiment, by determining the opposite plane of the seed crystal (determined according to requirements before growth. For example, if it is determined to grow a gallium oxide single crystal on the A plane, then select a seed crystal with the A plane, and make the A plane of the seed crystal parallel to the large plane of the mold during seed crystal alignment, where the A plane of the seed crystal is determined by an orientation instrument), using an adhesive strip-shaped thin sheet to extend it, it can provide a more intuitive and easier-to-operate calibration reference at the macroscopic level. Utilizing the unique design of the enlarged plane of the opposite plane of the seed crystal provides a simple and feasible way for aligning the opposite plane of the seed crystal with the mold and angle calibration.

[0036] The principle of this method is to bond a strip-shaped thin sheet with a relatively long length on the alignment plane of the seed crystal, so that the edge of the opposite plane of the seed crystal increases from the original small size (≤5 mm) to 50 mm or larger, and then determine the calibration of the opposite plane of the seed crystal according to the alignment or included angle between the long side of the enlarged strip-shaped thin sheet and the long side of the mold. The alignment method of long side to long side greatly reduces the calibration error. After alignment, gently peel off the strip-shaped thin sheet adhered to the seed crystal, and wipe the surface of the seed crystal with alcohol to complete the calibration of the seed crystal. This method is simple to operate, the required strip-shaped thin sheet is easy to obtain, and the strip-shaped thin sheet can be used repeatedly.

[0037] In addition, this method can be applied to other arbitrary angles between the seed crystal and the mold, or application scenarios with different seed crystal shapes, such as aligning the inclined angle β of the exposed surface of the growth seed crystal or the non-regular exposed surface type of the seed crystal. Calibration can be performed according to this enlarged plane.

[0038] The angle between the exposed surface of the seed crystal and the long side of the mold determines the crystal growth direction, which is the prerequisite for the growth crystal surface type and the main basis for the amount of blank material taken before processing. The operation process of this embodiment is simple and convenient, the identification method is reliable, and the material taking is convenient. It can greatly improve the accuracy of seed crystal alignment, reduce the error during small seed crystal alignment, and effectively reduce the probability of crystal growth skew. During the implementation of this embodiment, the furnace loading time can be shortened, while the crystal growth surface type is accurate, the material taking range of processing is increased, and the utilization rate of crystal blanks is improved.

[0039] For other methods that require seed crystal alignment, the seed crystal alignment method of this embodiment can be used. Magnify the seed crystal alignment surface to reduce the error of small seed crystal alignment, and ensure the accuracy rate of surface type growth and the efficiency of furnace loading. This method can achieve precise alignment and angle alignment between the seed crystal and the mold, providing good basic conditions for crystal growth. Precise angle calibration can effectively improve the utilization rate of blanks and reduce costs. The simple operation alignment method can significantly shorten the time required for seed crystal alignment, speed up the preliminary preparation work of crystal growth, and thus improve the efficiency of the entire production process. This has important economic significance for large-scale crystal production enterprises.

[0040] In one implementation manner, in step A, lower the seed crystal rod until the lower end of the seed crystal is 3 - 5 mm above the surface of the mold.

[0041] In one implementation manner, in step B, apply an adhesive to the middle position of the strip-shaped thin sheet, and attach the strip-shaped thin sheet below the alignment surface of the seed crystal. The adhesive used can be a temporary adhesive that is at room temperature, easy to clean, and does not damage the crystal according to the characteristics of the crystal (i.e., the seed crystal). For example, for gallium oxide crystals, an acrylate-based adhesive can be used.

[0042] In one implementation manner, in step B, the material of the strip-shaped thin sheet is gallium oxide single crystal.

[0043] In one implementation manner, in step D, after the step of removing the strip-shaped thin sheet, it further includes the step of wiping the bonding part between the seed crystal and the strip-shaped thin sheet clean with alcohol.

[0044] In a specific implementation manner, the seed crystal alignment method for growing single crystals by the guided mold method includes the steps:

[0045] Combined with Figure 3As shown, prepare the required strip-shaped wafer and adhesive. Lower the seed crystal rod until the lower end of the seed crystal is about 3 - 5 mm above the surface of the mold. At this time, take a small amount of adhesive and apply it to the middle position of the strip-shaped wafer, and then attach the strip-shaped wafer below the opposite plane of the seed crystal. Then, rotate the seed crystal to make the strip-shaped wafer parallel to the long side of the mold or at the required angle. After ensuring the angle is calibrated, remove the strip-shaped wafer and wipe the bonded part of the seed crystal and the strip-shaped wafer clean with alcohol. Finally, adjust the position of the seed crystal in the horizontal direction (i.e., the long side direction of the mold) so that the seed crystal is at the center of the mold to complete the alignment of the seed crystal.

[0046] In this embodiment, by determining the opposite plane of the seed crystal and using an adhesive strip-shaped wafer to extend it, it can provide a more intuitive and easier-to-operate calibration reference at the macroscopic level. Utilizing the unique design of the enlarged surface of the opposite plane of the seed crystal provides a simple and feasible way for aligning the opposite plane of the seed crystal with the mold and calibrating the angle. The operation of this embodiment is simple and convenient, the identification method is reliable, the materials are easy to obtain, it can greatly improve the accuracy of seed crystal alignment, reduce the errors occurring during the alignment of small seed crystals, and effectively reduce the probability of crystal growth skew. In addition, during the implementation of this embodiment, the furnace loading time can be shortened, the growth efficiency can be improved, at the same time, the crystal growth surface shape is accurate, the material selection range for processing is increased, and the utilization rate of crystal blanks is improved.

[0047] The embodiment of the present invention also provides a growth method for growing single crystals by the edge-defined film-fed growth (EFG) method, which includes the steps:

[0048] First, perform the alignment of the seed crystal by using the seed crystal alignment method for growing single crystals by the EFG method described in the embodiment of the present invention.

[0049] Then, keep the angle and the position in the horizontal direction of the seed crystal unchanged, lower the seed crystal rod, after the seed crystal contacts the melt on the surface of the mold, perform seeding, necking, shoulder opening, and equal-diameter growth in sequence to obtain the required single crystal.

[0050] By using the seed crystal alignment method of the embodiment of the present invention, the seed crystal can be effectively aligned, so as to ensure that the required surface shape of the seed crystal is parallel to the long side of the mold or at the required angle, and at the same time, the seed crystal is at the center position of the mold, thereby ensuring that the surface shape of the grown single crystal is accurate, and the size of the grown single crystal meets the requirements, increasing the material selection range for processing, and improving the utilization rate of single crystal blanks.

[0051] In one embodiment, the single crystal is a gallium oxide single crystal, and the surface shape of the gallium oxide single crystal is the 100 plane.

[0052] By using the seed crystal alignment method according to the embodiments of the present invention, the seed crystal alignment can be effectively achieved, thereby ensuring that the 100 plane of the seed crystal is parallel to the long side of the mold, and at the same time, the seed crystal is at the center position of the mold. Under the conditions of accurate placement position, angle, etc. of the seed crystal, the growth of gallium oxide single crystal is carried out, which can ensure that the grown gallium oxide single crystal has a 100-plane surface type and improve the accuracy of the surface type of the grown gallium oxide single crystal.

[0053] In one embodiment, the material of the mold is iridium.

[0054] In summary, the present invention provides a seed crystal alignment method and a single crystal growth method for growth of single crystal by the edge-defined film-fed growth (EFG) method. The seed crystal alignment method includes the steps of: preparing the required strip-shaped thin sheet and adhesive; lowering the seed crystal rod until the lower end of the seed crystal is about 3-5 mm above the surface of the mold, and at this time, applying a small amount of adhesive to the middle position of the strip-shaped thin sheet and attaching the strip-shaped thin sheet below the alignment surface of the seed crystal; then, rotating the seed crystal to make the strip-shaped thin sheet parallel to the long side of the mold or at the required angle; after ensuring the angle calibration, removing the strip-shaped thin sheet and wiping the bonded part of the seed crystal and the strip-shaped thin sheet with alcohol; finally, adjusting the position of the seed crystal in the horizontal direction (i.e., the long side direction of the mold) to make the seed crystal at the center of the mold, thus completing the seed crystal alignment. By determining the alignment surface of the seed crystal and extending it by using the bonded strip-shaped thin sheet, the present invention can provide a more intuitive and easier-to-operate calibration reference at the macroscopic level. By using the unique design of the enlarged surface of the seed crystal alignment surface, a simple and feasible way is provided for the alignment and angle calibration of the seed crystal alignment surface and the mold. The operation of the present invention is simple and convenient, the identification method is reliable, the materials are easy to obtain, it can greatly improve the accuracy of seed crystal alignment, reduce the error occurring during the alignment of small seed crystals, effectively reduce the probability of crystal growth deviation, improve the accuracy of crystal growth surface type, and at the same time increase the material selection range of processing and improve the utilization rate of crystal blanks. In addition, the present invention can shorten the furnace loading time and improve the growth efficiency during the implementation process.

[0055] It should be understood that the application of the present invention is not limited to the above examples. For those of ordinary skill in the art, improvements or transformations can be made according to the above description, and all such improvements and transformations should fall within the protection scope of the appended claims of the present invention.

Claims

1. A seed crystal alignment method for growing a single crystal by a guided mold method, characterized in that: Includes steps: Step A, lowering the seed crystal rod; Step B, determining the alignment surface of the seed crystal, and attaching the strip sheet below the alignment surface of the seed crystal; Step C, rotating the seed crystal so that the strip-shaped thin sheet is parallel to the long side of the mold or at a required angle; After step D and step C are completed, the strip sheet is removed; Step E: Finally, adjust the horizontal position of the seed crystal so that the seed crystal is in the center of the mold to complete the seed crystal alignment.

2. The seed crystal alignment method for growing a single crystal by a guided mold method according to claim 1, characterized in that: In step A, the seed crystal rod is lowered until the lower end of the seed crystal is 3-5 mm above the mold surface.

3. The seed crystal alignment method for growing a single crystal by a guided mold method according to claim 1, characterized in that: In the step B, an adhesive is applied to the middle of the strip-shaped thin sheet, and the strip-shaped thin sheet is attached below the alignment surface of the seed crystal.

4. The seed crystal alignment method for growing a single crystal by a guided mold method according to claim 1, characterized in that: In the step B, the material of the strip-shaped thin slice is gallium oxide single crystal.

5. The seed crystal alignment method for growing a single crystal by a guided mold method according to claim 1, characterized in that: In the step D, after the step of removing the strip sheet, the step of using alcohol to wipe clean the bonding portion between the seed crystal and the strip sheet is also included.

6. The seed crystal alignment method for growing a single crystal by a guided mold method according to claim 1, characterized in that: The single crystal is a gallium oxide single crystal.

7. A method for growing a single crystal by a guided mode method, characterized in that: Includes steps: Firstly, the seed crystal alignment method for growing a single crystal by a guided mold method as described in any one of claims 1 to 5 is used to align the seed crystal; Then, the angle and horizontal position of the seed crystal are kept unchanged, and the seed crystal rod is lowered so that the seed crystal contacts the melt on the mold surface. Then, seeding, necking, shouldering and equal-diameter growth are performed in sequence to obtain the desired single crystal.

8. The method for growing a single crystal by the guided mode method according to claim 7, characterized in that: The single crystal is a gallium oxide single crystal.

9. The method for growing a single crystal by the guided mode method according to claim 8, characterized in that: The face shape of the gallium oxide single crystal is 100 face.

10. The method for growing a single crystal by the guided mode method according to claim 8, characterized in that: The material of the mold is iridium.

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