Seed crystal assembly for casting monocrystalline silicon
By introducing buffer strips and covering layers into monocrystalline silicon seed crystal modules and optimizing the splicing seam design, the problems of thermal expansion stress and molten silicon infiltration at high temperatures in monocrystalline silicon seed crystals have been solved, thereby improving the quality and production efficiency of monocrystalline silicon.
Patent Information
- Application Number
- CN202520121367.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-20
- Publication Date
- 2025-12-12
- Estimated Expiration
- 2035-01-20
AI Technical Summary
In existing technologies, monocrystalline silicon seed crystals are prone to stress when they thermally expand at high temperatures, leading to mutual compression, plastic deformation, and dislocation sources, which affect the quality of monocrystalline silicon. At the same time, the splicing gap design has problems such as uneven temperature and molten silicon seepage.
Design a seed crystal assembly for casting monocrystalline silicon, including a monocrystalline silicon seed crystal, a buffer strip, and a cover layer. The buffer strip is attached to the edge of the seed crystal, and the cover layer is fixed above the splice seam to form an integral structure, optimizing the size and distribution of the splice seam.
It effectively alleviates thermal expansion stress, prevents seed crystal plastic deformation and polycrystalline silicon formation, improves monocrystalline silicon quality and module stability, simplifies manufacturing and assembly processes, and reduces costs.
Smart Images
Figure CN223660276U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to single crystal silicon seed crystal component structure technical field, specifically, relate to a seed crystal component for casting single crystal silicon. BACKGROUND
[0002] The single crystal silicon ingot is usually grown by directional solidification technology, and the process steps include the following key processes: first, the <100> crystal direction of the Czochralski single crystal silicon seed crystal is uniformly laid on the bottom of the quartz crucible according to the predetermined number and arrangement rule. Since the radial size of the cast single crystal silicon ingot is large, and the size of a single seed crystal is small, multiple seed crystals need to be combined and laid, and then the remaining silicon material is filled into the remaining space of the crucible.
[0003] During the melting and crystal growth process, the process control usually realizes the step-by-step melting of the silicon material from top to bottom. When the melt height reaches the seed crystal position, the melting is stopped and the crystal growth stage is entered. In the crystal growth stage, the height of the heat insulation cage is raised to form an effective heat dissipation channel, so that the heat at the lower part is dissipated through the cooling water in the hollow furnace chamber, while the five-side heater at the top continues to provide heating power, thereby forming a temperature gradient from the bottom to the top of the crucible, ensuring the directional growth of the single crystal silicon, and finally forming a high-quality single crystal silicon ingot.
[0004] However, in actual operation, since the single crystal silicon seed crystal will expand at high temperature, if no appropriate gap is reserved between adjacent seed crystals, the expansion will squeeze each other and generate stress, which may cause plastic deformation of the seed crystal and form dislocation sources. These dislocation sources will continue to expand during the growth of the silicon ingot, thereby significantly reducing the crystal quality of the final silicon ingot. In order to avoid such defects, the prior art usually relieves the expansion stress by reserving a certain size gap between adjacent seed crystals.
[0005] However, this method of reserving gaps also has certain technical limitations. Since the crucible for casting silicon ingot has a large radial size, the temperature distribution during heating is uneven, resulting in uneven crystallization degree and density of the crucible, thereby causing uneven overall shrinkage. If the size of the reserved gap is too large, the molten silicon liquid may seep into the gap and form polycrystalline silicon in the gap, which will reduce the quality of the single crystal silicon; and if the size of the gap is too small, the stress generated by the expansion of the seed crystal cannot be effectively relieved, and dislocation sources will still be formed, which cannot completely avoid the problem of crystal quality defects.
[0006] Therefore, the design of the cast single crystal silicon seed crystal assembly in the prior art still faces challenges, including how to effectively control the splicing gap to solve the problem of thermal expansion stress, and prevent the seepage of molten silicon liquid to cause the formation of polycrystalline silicon. These technical problems need to be improved and optimized to further improve the casting quality of single crystal silicon and improve the production efficiency. UTILITY MODEL CONTENT
[0007] The technical problem to be solved by the utility model is to provide a seed crystal assembly for casting monocrystalline silicon to solve the problem that conventional seed crystal assemblies in the prior art are prone to thermal expansion stress under high temperature conditions, thereby causing mutual extrusion between the seed crystals, plastic deformation, further inducing dislocation sources and reducing the quality of monocrystalline silicon.
[0008] In order to overcome the defects of the prior art, the utility model provides a seed crystal assembly for casting monocrystalline silicon, which comprises:
[0009] A plurality of monocrystalline silicon seeds, and the monocrystalline silicon seeds are in a cuboid structure;
[0010] A monocrystalline silicon buffer strip is arranged between adjacent monocrystalline silicon seeds, the two sides of the monocrystalline silicon buffer strip are respectively connected to the edges of adjacent monocrystalline silicon seeds, and the height of the monocrystalline silicon buffer strip is less than the height of the monocrystalline silicon seed, so that a joint exists between adjacent monocrystalline silicon seeds;
[0011] A monocrystalline silicon cover layer is arranged above the joint, the monocrystalline silicon cover layer is fixed to the top of two adjacent monocrystalline silicon seeds, so that the monocrystalline silicon cover layer, the adjacent monocrystalline silicon seeds and the monocrystalline silicon buffer strip form an integral fixed structure.
[0012] Compared with the prior art, the seed crystal assembly for casting monocrystalline silicon has the following advantages: effectively relieving thermal expansion stress, avoiding plastic deformation of the seed crystal and generation of dislocation sources; by arranging monocrystalline silicon buffer strips between adjacent monocrystalline silicon seeds, the buffer strips are connected to the edges of the seed crystals, can absorb stress caused by thermal expansion under high-temperature molten state, effectively avoid plastic deformation and stress concentration of the monocrystalline silicon seeds caused by thermal expansion, thereby reducing the formation of dislocation sources and improving the final quality of the monocrystalline silicon; the splicing joint design is optimized to prevent molten silicon liquid from seeping into the gap to form polysilicon; the height and width of the monocrystalline silicon buffer strip are designed to control the size of the splicing joint within a reasonable range, which can effectively prevent molten silicon liquid from seeping into the gap and forming polysilicon in the gap, thereby ensuring the continuity and crystal quality of the monocrystalline silicon; the cover layer is integrally fixed to improve the structural stability and prevent impurity pollution; the cover layer is directly placed above the splicing joint to form an integral structure with the monocrystalline silicon seeds and the buffer strips, effectively fixing the splicing joint area and further improving the structural stability of the seed crystal assembly. At the same time, the cover layer can reduce the contact area of the molten silicon liquid with the splicing joint area, reducing the possibility of impurity pollution and crystal defects; the structure is simple, facilitating large-scale production and assembly; the monocrystalline silicon buffer strip and the cover layer of the utility model are connected to the monocrystalline silicon seeds by direct lamination, without the need for additional adhesives or complex mechanical fixing means, thereby simplifying the structure of the assembly, reducing manufacturing and assembly costs, and improving the operability of industrial application; finally, by reasonably designing the buffer strip and the cover layer between the monocrystalline silicon seeds, the utility model effectively overcomes the thermal expansion stress problem and the splicing joint leakage problem in the prior art, significantly improves the reliability of the seed crystal assembly and the quality of the final silicon ingot during the monocrystalline silicon casting process, and has important application value and promotion potential in the casting process of large-size silicon ingots.
[0013] In a possible implementation, the cross section of the monocrystalline silicon seed is square.
[0014] Compared with the prior art, by adopting the above technical scheme, the cross section of the monocrystalline silicon seed is square, and since the square cross section can be seamlessly spliced (the four sides have equal sizes), high-density and uniform arrangement can be achieved at the bottom of the crucible, the gap area between the seeds is effectively reduced, the seed coverage is higher, the width of the splicing joint is reduced, the risk of forming polysilicon after the molten silicon liquid seeps into the splicing joint is effectively reduced, and the continuity of the monocrystalline silicon is ensured.
[0015] In a possible implementation, the cross section of the monocrystalline silicon seed is square.
[0016] Compared with the prior art, the size of the cross section is further selected, the arrangement of the seed crystal assembly and the thermal field distribution are optimized, and the material utilization rate and production flexibility are significantly improved, thereby solving the production problems caused by the non-standard seed crystal specification in the prior art, and providing stable and reliable technical support for the single crystal silicon casting process.
[0017] In a possible implementation, the height of the single crystal silicon seed crystal is 20-40 mm.
[0018] Compared with the prior art, the above technical solution not only meets the crystal guiding role of the seed crystal in the single crystal silicon growth process, but also maintains the structural integrity under the conditions of high-temperature melting and thermal expansion, and prevents thermal stress concentration caused by being too high or being unable to fully achieve crystal guiding caused by being too low.
[0019] In a possible implementation, the length of the single crystal silicon buffer strip is 80-100% of the length of the single crystal silicon seed crystal, the height of the single crystal silicon buffer strip is 5-10 mm, and the width of the single crystal silicon buffer strip is 0.1-0.5 mm.
[0020] Compared with the prior art, the height of the buffer strip is designed to be 5-10 mm, which is obviously smaller than the height of the single crystal silicon seed crystal of 20-40 mm, thereby realizing the design of the partially suspended splicing joint. The height difference can absorb the stress generated by the expansion of the single crystal silicon at high temperature, and provide a certain mechanical buffer space for the single crystal silicon seed crystal, effectively avoiding the direct extrusion between the single crystal silicon seed crystals. The length of the buffer strip is close to the length of the seed crystal (80-100%), which ensures that the buffer strip can cover the entire splicing area, avoids local stress concentration or uneven splicing joints, and provides more comprehensive stress relief function. The width of the buffer strip is the actual width of the splicing joint, which is set to 0.1-0.5 mm to ensure that there is enough gap between the seed crystals to absorb the thermal expansion stress, and to avoid the penetration of molten silicon into the gap due to the excessively wide splicing joint, thereby causing the nucleation of polycrystalline silicon. Through the reasonable design of the height, width and length of the single crystal silicon buffer strip, and the linkage with the height of the single crystal silicon seed crystal, the present embodiment realizes stress relief, thermal expansion isolation and crystal quality improvement in the single crystal silicon casting process, and finally solves the common crystal defects and polycrystalline silicon generation problems in the prior art.
[0021] In a possible implementation, the length of the single crystal silicon cover layer is equal to the length of the splicing joint, and the width of the single crystal silicon cover layer is greater than 1 / 3 of the width of the single crystal silicon seed crystal.
[0022] Compared with the prior art, the length of the covering layer is designed to be completely consistent with the length of the joint seam, which can ensure that the covering layer covers the joint seam in all directions, thereby avoiding exposure of the joint seam, effectively preventing the molten silicon liquid from penetrating into the joint seam and generating polycrystalline silicon in the gap, and the width of the covering layer is designed to be more than 1 / 3 of the width of the single crystal silicon seed crystal, which can ensure that the covering layer not only covers the joint seam but also extends partially to the top surface of the single crystal silicon seed crystal, further increasing the contact area between the covering layer and the single crystal silicon seed crystal, so that the covering layer has better mechanical fixing effect and thermal stability during the casting process. Through accurate design of the length and width of the covering layer, the present embodiment realizes complete coverage and sealing of the joint seam, significantly improves the mechanical strength and thermal stability of the assembly, effectively prevents penetration of the molten silicon liquid, prevents nucleation and growth of polycrystalline silicon, and provides additional mechanical fixing and thermal shielding effects, reduces the probability of generation of crystal defects, and enhances the stability of the crystal growth process, thereby improving the purity and final quality of the silicon ingot.
[0023] In a possible implementation manner, the height of the single crystal silicon covering layer is 5-10 mm.
[0024] Compared with the prior art, the height (5-10 mm) of the covering layer cooperates with the height (20-40 mm) of the single crystal silicon seed crystal and the height (5-10 mm) of the buffer strip to form a laminated linkage structure. During the casting process, the height of the covering layer can effectively balance the transmission of thermal expansion stress, and at the same time, provide a closed and supported effect on the joint seam area, which can cover the top area of the joint seam and avoid unnecessary material waste or thermal expansion effect caused by excessive height, and realize the organic combination of mechanical strength, thermal stability and sealing effect. BRIEF DESCRIPTION OF DRAWINGS
[0025] Fig. 1 is an exploded schematic view of a seed crystal assembly structure;
[0026] Figure 2 Fig. 2 is a schematic view of a joint of a seed crystal assembly structure;
[0027] Figure 3 Fig. 3 is a top view of a seed crystal assembly structure;
[0028] In the figure, 1 is a single crystal silicon seed crystal; 2 is a single crystal silicon buffer strip; 3 is a single crystal silicon covering layer; and 4 is a joint seam. DETAILED DESCRIPTION
[0029] Firstly, those skilled in the art should understand that the embodiments are only used to explain the technical principles of the present application, and are not intended to limit the protection scope of the present application. Those skilled in the art can make adjustments as needed to adapt to specific application occasions.
[0030] In the description of the embodiments of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "connected", "connected" should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected, it can be mechanically connected, or it can be electrically connected, it can be directly connected, or it can be indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.
[0031] In the embodiments of the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature can be above, above and above the second feature, or it can only mean that the horizontal height of the first feature is higher than that of the second feature. The first feature can be below, below and below the second feature, or it can only mean that the horizontal height of the first feature is less than that of the second feature.
[0032] The utility model provides a seed crystal assembly for casting monocrystalline silicon, the seed crystal assembly includes:
[0033] A plurality of monocrystalline silicon seeds 1, and the monocrystalline silicon seed 1 is a cuboid structure;
[0034] The monocrystalline silicon buffer strip 2 is arranged between adjacent monocrystalline silicon seeds 1, the two sides of the monocrystalline silicon buffer strip 2 are respectively connected with the edge of adjacent monocrystalline silicon seeds 1, and the height of the monocrystalline silicon buffer strip 2 is less than the height of the monocrystalline silicon seed 1, so that there is a joint seam 4 between adjacent monocrystalline silicon seeds 1;
[0035] And the monocrystalline silicon cover layer 3 is covered above the joint seam 4, the monocrystalline silicon cover layer 3 is fixed at the top of two adjacent monocrystalline silicon seeds 1, so that the monocrystalline silicon cover layer 3 and adjacent monocrystalline silicon seeds 1 and monocrystalline silicon buffer strip 2 form an integral fixed structure.
[0036] As a preferred scheme, the cross section of the monocrystalline silicon seed 1 is square.
[0037] As a preferred scheme, the size of the cross section of the monocrystalline silicon seed 1 is one of 160mm*160mm, 184mm*184mm or 212mm*212mm.
[0038] As a preferred scheme, the height of the monocrystalline silicon seed 1 is 20-40mm.
[0039] As a preferred scheme, the length of the single crystal silicon buffer strip 2 is 80-100% of the length of the single crystal silicon seed crystal 1, the height of the single crystal silicon buffer strip is 5-10 mm, and the width of the single crystal silicon buffer strip 2 is 0.1-0.5 mm.
[0040] As a preferred scheme, the length of the single crystal silicon cover layer 3 is equal to the length of the splicing joint 4, and the width of the single crystal silicon cover layer 3 is greater than 1 / 3 of the width of the single crystal silicon seed crystal 1.
[0041] As a preferred scheme, the height of the single crystal silicon cover layer 3 is 5-10 mm.
[0042] Referring to FIG. 1, Figure 1 , Figure 2 The utility model discloses a seed crystal assembly for casting single crystal silicon, the seed crystal assembly includes a plurality of single crystal silicon seed crystals 1, single crystal silicon buffer strip 2 and single crystal silicon cover layer 3,
[0043] The structure and arrangement of the single crystal silicon seed crystal 1 are as follows:
[0044] The single crystal silicon seed crystal 1 is a cuboid structure, and the cross section thereof is a square, and the specific size is one of three specifications of 160mm*160mm, 184mm*184mm or 212mm*212mm. The height of the single crystal silicon seed crystal 1 is designed to be 20-40 mm, and is selected according to actual casting requirements.
[0045] In actual installation and application, the single crystal silicon seed crystal 1 is uniformly laid on the bottom of the quartz crucible according to a predetermined arrangement rule, the single crystal silicon buffer strip 2 is arranged between adjacent single crystal silicon seed crystals 1 to form a splicing joint 4, and the single crystal silicon buffer strip 2 and the single crystal silicon seed crystal 1 are in close contact with each other. This arrangement mode effectively improves the overall utilization rate and stability of the seed crystal assembly and avoids the problem of crystal quality caused by irregular arrangement.
[0046] The single crystal silicon buffer strip 2 is arranged between adjacent single crystal silicon seed crystals 1, and the two sides thereof are connected with the edges of the adjacent single crystal silicon seed crystals 1. The length of the single crystal silicon buffer strip 2 is 80-100% of the length of the single crystal silicon seed crystal 1. Figure 1 As shown in FIG. 2, the length of the single crystal silicon buffer strip 2 described in the application is a vertical value in FIG. 2. Figure 1 The height of the single crystal silicon buffer strip is 5-10 mm, and the width thereof is 0.1-0.5 mm. Figure 1 The width is a horizontal value in FIG. 2.
[0047] The height of the single crystal silicon buffer strip 2 is obviously smaller than the height of the single crystal silicon seed crystal, specifically 10-35 mm, and the single crystal silicon buffer strip 2 is used to form a certain buffer space in the splicing joint area, so that the stress caused by thermal expansion can be effectively absorbed, and direct extrusion between the single crystal silicon seed crystals 1 is avoided.
[0048] The single crystal silicon cover layer 3 is arranged above the splicing joint 4, and the length of the single crystal silicon cover layer 3 is equal to the length of the splicing joint, and the length of the single crystal silicon cover layer 3 is a value in the vertical direction, and the width is greater than 1 / 3 of the width of the single crystal silicon seed crystal 1, and the width is a value in the horizontal direction. Figure 1 Figure 1 The length of the single crystal silicon cover layer 3 is a value in the vertical direction, and the width is greater than 1 / 3 of the width of the single crystal silicon seed crystal 1, and the width is a value in the horizontal direction.
[0049] The single crystal silicon cover layer 3 is fixed on the top of the single crystal silicon seed crystal 1, and forms an integral fixed structure with the adjacent single crystal silicon seed crystal 1 and the single crystal silicon buffer strip 2, and the design of the cover layer not only seals the splicing joint, but also enhances the overall strength and thermal stability of the seed crystal assembly through the mechanical support on the top.
[0050] In order to further guarantee the functionality of the utility model, the splicing joint in the utility model is optimized and designed: the width of the splicing joint 4 is controlled by the width of the single crystal silicon buffer strip 2, and is 0.1-0.5 mm. Through the design of the buffer strip, the size of the splicing joint is strictly controlled, which can not only provide sufficient buffer space to avoid mutual extrusion of the single crystal silicon seed crystals 1 due to thermal expansion, but also prevent molten silicon liquid from seeping into the splicing joint to form polycrystalline silicon, so as to guarantee the purity and quality of the single crystal silicon.
[0051] The thermal shielding effect of the cover layer: the height of the single crystal silicon cover layer 3 is 5-10 mm, which can provide effective thermal shielding effect during crystal growth, slow down the temperature gradient change in the splicing joint area, and reduce the crystal defects caused by thermal stress concentration.
[0052] The linkage effect of the overall structure of the assembly: the height of the single crystal silicon buffer strip 2 is the same as that of the single crystal silicon cover layer 3 (both are 5-10 mm), so that a closed protection structure is formed in the upper and lower areas of the splicing joint, and the height of the single crystal silicon seed crystal 1 is 20-40 mm, which ensures the crystal guiding function, and the buffer strip and the cover layer jointly provide additional mechanical strength and thermal expansion stress relief function.
[0053] The material selection of the buffer strip: the single crystal silicon buffer strip 2 is made of single crystal silicon material, so as to further improve the thermal deformation resistance.
[0054] The fixing mode of the cover layer: the single crystal silicon cover layer 3 can be fixed on the top of the single crystal silicon seed crystal 1 in a direct and close-fitting manner, so as to ensure the reliability of the cover layer in a high-temperature environment.
[0055] Figure 3 For the top view of the seed crystal assembly structure, it can be seen fromFigure 3 As seen, the length of the single crystal silicon covering layer in the vertical direction is equal to the length of the splicing joint 4, so that the splicing joint 4 can be completely covered, and the width in the horizontal direction is greater than 1 / 3 of the width of the single crystal silicon seed crystal 1.
[0056] Working principle and installation mode:
[0057] In the installation, first, multiple single crystal silicon seed crystals 1 are laid on the bottom of the crucible according to the predetermined arrangement rule, the single crystal silicon buffer strips 2 are inserted between the adjacent seed crystals, the single crystal silicon buffer strips 2 can be inserted in front of, behind, left and right of the single crystal silicon seed crystal 1, or the required direction is selected to insert and match the adjacent single crystal silicon seed crystal 1, then, the single crystal silicon covering layer 3 is placed above the splicing joint, and is fixed through the mechanical lamination, the directional growth of the single crystal silicon is realized by controlling the molten silicon liquid height and the thermal field distribution in the casting process, and finally the high-quality silicon ingot is formed.
[0058] The single crystal silicon seed crystal 1, the single crystal silicon buffer strip 2 and the single crystal silicon covering layer 3 are reasonably designed, the problems of stress concentration, polycrystalline silicon nucleation and crystal defects caused by thermal expansion in the prior art are solved, and the following technical effects are realized: the purity and the crystal integrity of the single crystal silicon are significantly improved, the thermal field distribution is optimized, the thermal stress and the crack defect are reduced, the stability and the anti-deformation ability of the overall structure of the assembly are enhanced, the energy loss and the material waste in the crystal growth process are reduced, and the compact structure, the high thermal stability, the easy industrialization promotion, the effective solution to the problems of the thermal expansion stress concentration, the splicing joint polycrystalline nucleation and the crystal defects in the prior art, and the reliable technical support for casting high-quality single crystal silicon are realized.
[0059] In the description of the embodiments of the application, it should be explained that, in the description of the application, the terms indicating the direction or position relationship such as "inner", "outer" and the like are based on the direction or position relationship shown in the drawings, which is only for the convenience of description, and does not indicate or imply that the device or member must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the application.
[0060] In the description of the application, the description of the terms "one embodiment", "some embodiments", "in this embodiment", "specific example", or "some examples" and the like means that the specific features, mechanisms, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the application. In the description, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.
[0061] The above description is merely a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.
Claims
1. A seed assembly for use in the casting of single crystal silicon, characterized by, The seed crystal assembly comprises: a plurality of single crystal silicon seeds (1), and the single crystal silicon seeds (1) are in a cuboid structure; a single crystal silicon buffer strip (2) arranged between adjacent single crystal silicon seeds (1), two sides of the single crystal silicon buffer strip (2) are respectively connected with edges of adjacent single crystal silicon seeds (1), and a height of the single crystal silicon buffer strip (2) is less than a height of the single crystal silicon seed (1), so that a joint seam (4) exists between adjacent single crystal silicon seeds (1); and a single crystal silicon cover layer (3) covering the joint seam (4), the single crystal silicon cover layer (3) being fixed on top of two adjacent single crystal silicon seeds (1).
2. The seed assembly for casting single crystal silicon of claim 1, wherein, The single crystal silicon seed (1) is in a square cross section.
3. The seed assembly for casting single crystal silicon according to claim 1 or 2, characterized in that, The single crystal silicon seed (1) is in one of three specifications of 160mm*160mm, 184mm*184mm or 212mm*212mm in size of the cross section.
4. The seed assembly for casting single crystal silicon of claim 3, wherein, The single crystal silicon seed (1) is 20-40mm in height.
5. The seed assembly for casting single crystal silicon of claim 4, wherein, The single crystal silicon buffer strip (2) is 80-100% of the single crystal silicon seed (1) in length, 5-10mm in height, and 0.1-0.5mm in width.
6. The seed assembly for casting single crystal silicon of claim 4, wherein, The single crystal silicon cover layer (3) is 5-10mm in height.
7. The seed assembly for casting single crystal silicon of claim 1 wherein, The single crystal silicon cover layer (3) is equal to the joint seam (4) in length, and greater than 1 / 3 of the single crystal silicon seed (1) in width.