CN111876821A - Cast monocrystalline silicon ingot and preparation method thereof, cast monocrystalline silicon piece and preparation method thereof - Google Patents
Cast monocrystalline silicon ingot and preparation method thereof, cast monocrystalline silicon piece and preparation method thereof Download PDFInfo
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- CN111876821A CN111876821A CN202010758499.8A CN202010758499A CN111876821A CN 111876821 A CN111876821 A CN 111876821A CN 202010758499 A CN202010758499 A CN 202010758499A CN 111876821 A CN111876821 A CN 111876821A
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- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
- C30B11/14—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method characterised by the seed, e.g. its crystallographic orientation
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
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Abstract
The invention relates to a cast monocrystalline silicon ingot and a preparation method thereof, and a cast monocrystalline silicon piece and a preparation method thereof. The preparation method of the cast monocrystalline silicon ingot comprises the following steps: laying and recovering single crystal seeds at the bottom of the container to form a single crystal seed layer; the direction of the recovered single crystal seed crystal from the bottom of the container to the bottom of the container is a first direction, and the first direction is the same as the growth direction of the original crystal of the recovered single crystal seed crystal; and (3) loading a silicon material on the monocrystalline seed crystal layer, heating to completely melt the silicon material and partially melt the monocrystalline seed crystal layer, and growing crystals to obtain the cast monocrystalline silicon ingot. According to the preparation method of the cast monocrystalline silicon ingot, the growth direction of the defects in the recovered monocrystalline seed crystal is changed in the crystal growth process, the defects in the recovered monocrystalline seed crystal are utilized to guide the subsequent defects to expand in the direction opposite to the previous direction, the defects of the cast ingot monocrystalline silicon ingot grown by using the recovered monocrystalline seed crystal are not expanded and propagated continuously along the original direction, but are gradually narrowed or even disappear, and the yield of the cast monocrystalline silicon ingot is improved.
Description
Technical Field
The invention relates to the technical field of solar photovoltaic materials, in particular to a cast monocrystalline silicon ingot and a preparation method thereof, a cast monocrystalline silicon piece and a preparation method thereof.
Background
Solar photovoltaic power generation is one of the fastest-developing forms of sustainable energy utilization, and is rapidly developed in all countries in recent years. Currently, a method for producing a single crystal silicon for solar use by a casting method is receiving more and more attention. The cast monocrystalline silicon has the advantage of low defect of czochralski monocrystalline silicon, and a pyramid-shaped texture can be formed by an alkali texturing method, so that the absorption of light is improved, and the conversion efficiency is improved; meanwhile, the cast monocrystalline silicon also has the advantages of low production cost and high yield of cast polycrystalline silicon. Therefore, the cast monocrystalline silicon inherits the advantages of the czochralski monocrystalline silicon and the cast polycrystalline silicon, overcomes the respective defects of the two modes, and the quality of the produced monocrystalline silicon is close to that of the czochralski monocrystalline silicon. The conversion efficiency of the battery is improved by more than 1% on the premise of not obviously increasing the cost of the silicon chip. Becomes an important way to reduce the production cost of the solar cell.
At present, a czochralski single crystal square is generally adopted as a seed crystal for casting a single crystal, and a square ingot of the casting single crystal is grown on the seed crystal. Because the cost of the czochralski single crystal as the seed crystal of the cast single crystal is higher, seed crystals are recycled by manufacturers of the cast single crystal, and the square seed crystal of the czochralski single crystal is called as new seed crystal. And intercepting a part of the silicon ingot grown by the new seed crystal to be used as the seed crystal for recycling, wherein the type of the single crystal seed crystal is called as a recovered single crystal seed crystal. Because dislocation defects are generated in the new single crystal seed crystal after the new single crystal seed crystal is used for the first time (hereinafter referred to as recovered single crystal seed crystal), when the new single crystal seed crystal is used again, the cast single crystal grows at the dislocation defects of the recovered single crystal seed crystal, the dislocation defects grow and proliferate along with the dislocation defects, and the yield and the quality of the cast single crystal silicon ingot are reduced.
Disclosure of Invention
In view of the above, it is necessary to provide a cast silicon single crystal ingot and a method for producing the same, a cast silicon single crystal wafer and a method for producing the same, in order to solve the problem of how to increase the yield of cast silicon single crystal ingots.
A preparation method of a cast monocrystalline silicon ingot comprises the following steps:
laying and recovering single crystal seeds at the bottom of the container to form a single crystal seed layer; the direction from the bottom of the recovered single crystal seed crystal to the bottom of the container is a first direction, and the first direction is the same as the growth direction of the original crystal of the recovered single crystal seed crystal;
and (3) loading a silicon material on the monocrystalline seed crystal layer, heating to completely melt the silicon material and partially melt the monocrystalline seed crystal layer, and growing crystals to obtain the cast monocrystalline silicon ingot.
According to the preparation method of the cast monocrystalline silicon ingot, the first direction is the same as the growth direction of the original crystal of the recovered monocrystalline seed crystal, so that the growth direction of the defects in the recovered monocrystalline seed crystal is changed in the crystal growing process, and the defects in the recovered monocrystalline seed crystal are expanded in the direction opposite to the previous direction due to the fact that the defects in the monocrystalline seed crystal are expanded in a preferred orientation, so that the defects of the ingot casting monocrystalline silicon ingot grown by using the recovered monocrystalline seed crystal are not expanded and propagated along the original direction any more, but are gradually narrowed or even disappear, and the yield of the cast monocrystalline silicon ingot is improved.
In one embodiment, the step of laying the recovered single crystal seed crystal at the bottom of the container is as follows:
cutting the tail part of the finished cast monocrystalline silicon ingot, and obtaining recovered monocrystalline seed crystals after mechanical processing and cleaning;
and inversely spreading the recovered single crystal seed crystals at the bottom of the container according to the direction opposite to the growth direction of the original crystal.
In one embodiment, the thickness of the single crystal seed layer is 10mm to 50 mm.
In one embodiment, the supercooling degree is 0-50 in the crystal growth process.
In one embodiment, the step of heating to completely melt the silicon raw material and partially melt the single crystal seed layer, and obtaining the cast single crystal silicon ingot after crystal growth comprises:
heating the container to completely melt the silicon raw material and partially melt the single crystal seed crystal layer to form a liquid layer, and at least keeping the part of the single crystal seed crystal layer contacted with the bottom of the container to be solid;
and controlling a thermal field in the container, crystallizing the liquid layer to form a crystallization layer, and moving a solid-liquid interface in a direction far away from the bottom of the container to finish the growth of the cast monocrystalline silicon ingot.
In one embodiment, the single crystal seed layer comprises a plurality of recovered single crystal seeds spliced with each other, and the adjacent recovered single crystal seeds are in close contact with each other.
In one embodiment, the method further comprises the step of slicing the cast single crystal silicon ingot to a predetermined size.
A cast single crystal silicon ingot prepared by the method of preparing a cast single crystal silicon ingot of any of the above embodiments.
According to the preparation method of the cast monocrystalline silicon ingot, the first direction is the same as the growth direction of the original crystal of the recovered monocrystalline seed crystal, so that the growth direction of the defects in the recovered monocrystalline seed crystal is changed in the crystal growth process, and the defects in the recovered monocrystalline seed crystal are expanded preferentially, so that the defects of the ingot casting monocrystalline silicon ingot grown by using the recovered monocrystalline seed crystal are not expanded and propagated continuously along the original direction, but are gradually narrowed or even disappear. Therefore, the cast monocrystalline silicon ingot prepared by the preparation method of the cast monocrystalline silicon ingot has fewer defects, and the yield of the cast monocrystalline silicon ingot is improved.
A preparation method of a cast monocrystalline silicon piece comprises the following steps:
and slicing the cast monocrystalline silicon ingot to obtain a cast monocrystalline silicon wafer.
According to the preparation method of the cast monocrystalline silicon piece, the first direction is the same as the growth direction of the original crystal of the recovered monocrystalline seed crystal, so that the growth direction of the defects in the recovered monocrystalline seed crystal is changed in the crystal growth process, and the defects in the recovered monocrystalline seed crystal are expanded in the direction opposite to the previous direction due to the fact that the defects in the monocrystalline seed crystal are expanded in a preferred orientation, so that the defects of the ingot casting monocrystalline silicon ingot grown by using the recovered monocrystalline seed crystal are not expanded and propagated along the original direction any more, but are gradually narrowed or even disappear, and the yield of the cast monocrystalline silicon ingot and the cast monocrystalline silicon piece is improved.
A cast monocrystalline silicon piece is prepared by the preparation method of the cast monocrystalline silicon piece.
The cast monocrystalline silicon wafer obtained by the preparation method has fewer defects, higher ingot quality and higher silicon wafer efficiency, and can reduce cost and improve efficiency.
Drawings
FIG. 1 is a flow chart of a method of manufacturing a cast single crystal silicon ingot in accordance with one embodiment of the present invention;
FIG. 2 is a schematic illustration of slicing a cast single crystal silicon ingot during preparation of the cast single crystal silicon ingot in accordance with one embodiment of the present invention;
FIG. 3 is a schematic view of a recovered monocrystalline seed crystal obtained during the preparation of a cast monocrystalline silicon ingot in accordance with one embodiment of the present invention;
FIG. 4 is a schematic representation of a cast single crystal silicon ingot during production with the recovered single crystal seed crystal inverted in accordance with one embodiment of the present invention;
FIG. 5 is a schematic view of a crucible and a monocrystalline seed layer during preparation of a cast monocrystalline silicon ingot in accordance with one embodiment of the present invention;
FIG. 6 is a schematic view of the placement of a single crystal seed recovered from a single crystal seed layer during the preparation of a cast single crystal silicon ingot in accordance with one embodiment of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.
It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
The applicant finds that when new single crystal seed crystals are laid, a splicing seam exists between the two single crystal seed crystals, defects are easily formed at the splicing seam when the single crystal seed crystals are cast for crystal growth, and the defects can be expanded from the splicing seam to two sides, so that the yield of cast single crystal silicon ingots is reduced, and the quality is reduced. In order to solve the problems, the invention provides a cast monocrystalline silicon ingot and a preparation method thereof, a cast monocrystalline silicon piece and a preparation method thereof.
Referring to fig. 1, a method for preparing a cast silicon single crystal ingot according to an embodiment of the present invention includes the following steps:
s10, laying and recovering single crystal seeds at the bottom of the container to form a single crystal seed crystal layer; the direction from the bottom of the recovered single crystal seed crystal to the bottom of the container is the first direction, and the first direction is the same as the growth direction of the original crystal of the recovered single crystal seed crystal.
The shape and material of the vessel in the present invention are determined by the vessel used in the production process, and generally, since the single crystal silicon ingot is produced by casting in the present invention, the vessel is a crucible, and more generally, a quartz crucible. Of course, the vessel may alternatively be a disposable or reusable crucible that may be used in the casting process for casting single crystal silicon ingots, such as silicon carbide or silicon nitride crucibles.
The "casting" process in this embodiment specifically refers to forming a silicon ingot by cooling molten silicon in a mold or vessel for holding the molten silicon. Generally, a Directional Solidification System (DSS) furnace crystal growth technology is commonly used at present, and a large square cast monocrystalline silicon wafer can be produced by using the technology, so that the cost of downstream battery processing is reduced.
Wherein, the recovered single crystal seed crystal is single crystal silicon with fixed crystallographic orientation, and the recovered single crystal seed crystal has defects formed during crystal growth. The monocrystalline seed layer includes at least one layer of a monocrystalline silicon having a crystallographic orientation.
Wherein, the original crystal growth direction of the recovered single crystal seed crystal refers to the growth direction of the crystal in the initial state of the recovered single crystal seed crystal.
In one embodiment, the step of laying the recovered single crystal seed crystal at the bottom of the container is as follows:
cutting the tail part of the finished cast monocrystalline silicon ingot, and obtaining recovered monocrystalline seed crystals after mechanical processing and cleaning;
and inversely spreading the recovered single crystal seed crystals at the bottom of the container in the direction opposite to the growth direction of the original crystal.
Referring also to FIG. 2, finished cast single crystal silicon ingot 100 is sliced along the plane of the dashed line in FIG. 2 to obtain recovered single crystal seed crystal 120 shown in FIG. 3. The direction indicated by the arrow in fig. 2 and 3 is the direction of the original crystal growth from which the single crystal seed crystal was recovered.
The recovered single crystal seed crystal 120 is then inverted in a direction opposite to the direction of original crystal growth, as shown in fig. 4. The direction indicated by the arrow in FIG. 4 is the direction of the original crystal growth from which the single crystal seed crystal was recovered.
Referring also to fig. 5, a plurality of inverted recovered single crystal seeds 120 are deposited at the bottom of the container 200.
In one embodiment, the single crystal seed layer 130 includes a plurality of recovered single crystal seeds 120 that are spliced together, with adjacent recovered single crystal seeds 120 in intimate contact, as shown in fig. 5 and 6. This makes it possible to minimize the gaps between the recovered single crystal seeds, thereby reducing grain boundaries and dislocations introduced at the seed gaps.
In one embodiment, the recovered single crystal seeds 120 are square in cross-section parallel to the bottom surface of the vessel, and a plurality of recovered single crystal seeds 120 are arranged in rows and columns.
In the present invention, the shape and size of the single crystal seed crystal are not limited, and the single crystal seed crystal layer may be a large single crystal seed crystal having substantially the same size and shape as the bottom of the container, or may be formed by tiling a plurality of small single crystal seed crystals. If the crystal is the latter, in order to facilitate the laying process and meet the requirement of complete tiling, the cross-sectional shape of the single crystal seed crystal is preferably regular geometric shape, preferably the shape of the single crystal seed crystal is rectangular, more preferably square, and the larger single crystal seed crystal is selected as much as possible, so that the gap between the single crystal seeds formed by tiling is as small as possible, and the yield of the cast single crystal silicon ingot is ensured.
In the present invention, the method of laying the single crystal seed layer is not particularly limited, but in order to ensure the quality of the single crystal silicon in the cast single crystal silicon ingot, it is preferable that the single crystal seed layer is laid in the middle region of the vessel. In addition, the single crystal seed layer should remain substantially parallel or nearly parallel to the bottom of the vessel for better control of the manufacturing process and quality of the cast single crystal silicon ingot.
In one embodiment, the thickness of the single crystal seed layer 130 is between 10mm and 50 mm. More preferably, the thickness of the single crystal seed layer 130 is 15mm to 25 mm. It should be noted that the thickness of the single crystal seed layer is not particularly limited in the present invention, and depends on the specific production process and production conditions.
And S20, loading the silicon material on the monocrystalline seed crystal layer, heating to completely melt the silicon material and partially melt the monocrystalline seed crystal layer, and growing crystals to obtain the cast monocrystalline silicon ingot.
In one embodiment, the supercooling degree is 0-50 in the crystal growth process. Preferably, the supercooling degree is 2-6 in the crystal growth process.
In one embodiment, the step of heating to completely melt the silicon raw material and partially melt the single crystal seed layer, and obtaining the cast single crystal silicon ingot after crystal growth comprises:
heating the container to completely melt the silicon raw material and partially melt the single crystal seed crystal layer to form a liquid layer, and at least keeping the part of the single crystal seed crystal layer contacted with the bottom of the container to be solid;
and controlling a thermal field in the container, crystallizing the liquid layer to form a crystallization layer, and moving a solid-liquid interface in a direction far away from the bottom of the container to finish the growth of the cast monocrystalline silicon ingot.
In one embodiment, the method further comprises the step of slicing (i.e., squaring) the cast silicon single crystal ingot obtained in step S20 to a predetermined size.
According to the preparation method of the cast monocrystalline silicon ingot, the first direction is the same as the growth direction of the original crystal of the recovered monocrystalline seed crystal, so that the growth direction of the defects in the recovered monocrystalline seed crystal is changed in the crystal growing process, and the defects in the recovered monocrystalline seed crystal are expanded in the direction opposite to the previous direction due to the fact that the defects in the monocrystalline seed crystal are expanded in a preferred orientation, so that the defects of the ingot casting monocrystalline silicon ingot grown by using the recovered monocrystalline seed crystal are not expanded and propagated along the original direction any more, but are gradually narrowed or even disappear, and the yield of the cast monocrystalline silicon ingot is improved.
According to the preparation method of the cast monocrystalline silicon ingot, the recycling cost of the recycled monocrystalline seed crystals is reduced, and the quality and the yield of the cast monocrystalline silicon ingot are improved, so that the manufacturing cost of the cast monocrystalline is reduced, and the market competitiveness of the cast monocrystalline is improved.
The cast single crystal silicon ingot according to an embodiment of the present invention is prepared by the method for preparing a cast single crystal silicon ingot according to any one of the above-described examples.
According to the preparation method of the cast monocrystalline silicon ingot, the first direction is the same as the growth direction of the original crystal of the recovered monocrystalline seed crystal, so that the growth direction of the defects in the recovered monocrystalline seed crystal is changed in the crystal growth process, and the defects in the recovered monocrystalline seed crystal are expanded preferentially, so that the defects of the ingot casting monocrystalline silicon ingot grown by using the recovered monocrystalline seed crystal are not expanded and propagated continuously along the original direction, but are gradually narrowed or even disappear. Therefore, the cast monocrystalline silicon ingot prepared by the preparation method of the cast monocrystalline silicon ingot has fewer defects, and the yield of the cast monocrystalline silicon ingot is improved.
The method for preparing a cast monocrystalline silicon wafer according to an embodiment of the present invention includes the steps of:
and slicing the cast monocrystalline silicon ingot to obtain a cast monocrystalline silicon wafer. According to the preparation method of the cast monocrystalline silicon piece, the first direction is the same as the growth direction of the original crystal of the recovered monocrystalline seed crystal, so that the growth direction of the defects in the recovered monocrystalline seed crystal is changed in the crystal growth process, and the defects in the recovered monocrystalline seed crystal are expanded in the direction opposite to the previous direction due to the fact that the defects in the monocrystalline seed crystal are expanded in a preferred orientation, so that the defects of the ingot casting monocrystalline silicon ingot grown by using the recovered monocrystalline seed crystal are not expanded and propagated along the original direction any more, but are gradually narrowed or even disappear, and the yield of the cast monocrystalline silicon ingot and the cast monocrystalline silicon piece is improved.
The cast single crystal silicon wafer according to an embodiment of the present invention is produced by the above-described method for producing a cast single crystal silicon wafer.
The cast monocrystalline silicon wafer obtained by the preparation method has fewer defects, higher ingot quality and higher silicon wafer efficiency, and can reduce cost and improve efficiency.
The cast single crystal silicon ingot and the method of producing the same, the cast single crystal silicon wafer and the method of producing the same according to the present invention will be further described with reference to the following specific examples.
Examples 1 to 13
Splicing 36 pieces of recovered single crystal seed crystals with the thickness of 20mm and the length and the width of 160mm in a row-by-row mode according to a certain sequence, and paving the single crystal seed crystals at the bottom of a crucible according to a first direction to form the single crystal seed crystal layer.
And then, filling silicon materials on the monocrystalline seed crystal layer, melting the silicon materials in an ingot furnace, and carrying out crystal growth, annealing, cooling and other process treatments with the supercooling degree of 5 to obtain the cast monocrystalline silicon ingot.
And obtaining 36 qualified small cast single crystal ingots after squaring and detecting the cast single crystal silicon ingot. And dividing the total weight of the qualified small square ingots of the cast single crystals by the total material loading to obtain the number, namely the yield of the cast single crystals. The results are shown in Table 1, and the average yield of cast single crystals is 45.32%.
Comparative examples 1 to 13
Splicing 36 pieces of recovered single crystal seed crystals with the thickness of 20mm and the length and the width of 160mm in a row-to-column mode, and paving the single crystal seed crystals at the bottom of the crucible in a direction opposite to the first direction to form the single crystal seed crystal layer.
And then, filling silicon materials on the monocrystalline seed crystal layer, melting the silicon materials in an ingot furnace, and carrying out crystal growth, annealing, cooling and other process treatments with the supercooling degree of 5 to obtain the cast monocrystalline silicon ingot.
And obtaining 36 qualified small cast single crystal ingots after squaring and detecting the cast single crystal silicon ingot. And dividing the total weight of the qualified small square ingots of the cast single crystals by the total material loading to obtain the number, namely the yield of the cast single crystals. The results are shown in Table 1, and the average yield of the cast single crystal is 42.52%.
Wherein, the difference of the defect values of the example 1 and the recovered single crystal seed crystal in the comparative example 1 is less than 0.2. Among them, defects in the cast single crystal silicon ingot are mainly dislocation defects, and exhibit an aggregated linear distribution, which exhibits a recombination center during photoluminescence, reduces the luminance, and is darker than surrounding defect-free regions. The defect value is actually the defect density or defect percentage, which is the percentage of the area of the darkened area over the entire area. In addition, the embodiment 2 corresponds to the recovered single crystal seed crystals in the comparative example 2, and by analogy, the embodiments 1 to 13 correspond to the comparative examples 1 to 13 one by one in sequence, and the difference of the corresponding recovered single crystal seed crystals is less than 0.2.
TABLE 1 yield of cast single crystal silicon ingots for examples and comparative examples
As can be seen from table 1, the yield of the cast silicon single crystal ingots of examples 1 to 13 is higher than that of the corresponding comparative examples 1 to 13 in each of examples 1 to 13, compared to the corresponding comparative examples 1 to 13. And the average yield of the cast silicon single crystal ingots of examples 1 to 13 was 2.8% higher than that of the cast silicon single crystal ingots of comparative examples 1 to 13. The results show that the yield of the cast monocrystalline silicon ingot can be improved by adopting the preparation method of the cast monocrystalline silicon ingot.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A preparation method of a cast monocrystalline silicon ingot is characterized by comprising the following steps:
laying and recovering single crystal seeds at the bottom of the container to form a single crystal seed layer; the direction from the bottom of the recovered single crystal seed crystal to the bottom of the container is a first direction, and the first direction is the same as the growth direction of the original crystal of the recovered single crystal seed crystal;
and (3) loading a silicon material on the monocrystalline seed crystal layer, heating to completely melt the silicon material and partially melt the monocrystalline seed crystal layer, and growing crystals to obtain the cast monocrystalline silicon ingot.
2. The method of preparing a cast single crystal silicon ingot as set forth in claim 1 wherein the step of laying a recovered single crystal seed crystal at the bottom of the vessel comprises:
cutting the tail part of the finished cast monocrystalline silicon ingot, and obtaining recovered monocrystalline seed crystals after mechanical processing and cleaning;
and inversely spreading the recovered single crystal seed crystals at the bottom of the container according to the direction opposite to the growth direction of the original crystal.
3. The method of claim 1, wherein the monocrystalline seed layer has a thickness of 10mm to 50 mm.
4. The method of claim 1, wherein the supercooling degree is 0 to 50 during the growing process.
5. The method of manufacturing a cast single crystal silicon ingot according to claim 1, wherein the step of heating the ingot to completely melt the silicon raw material and partially melt the single crystal seed layer, and obtaining the cast single crystal silicon ingot after the crystal growth comprises:
heating the container to completely melt the silicon raw material and partially melt the single crystal seed crystal layer to form a liquid layer, and at least keeping the part of the single crystal seed crystal layer contacted with the bottom of the container to be solid;
and controlling a thermal field in the container, crystallizing the liquid layer to form a crystallization layer, and moving a solid-liquid interface in a direction far away from the bottom of the container to finish the growth of the cast monocrystalline silicon ingot.
6. The method of preparing a cast single crystal silicon ingot as set forth in claim 1 wherein the single crystal seed layer comprises a plurality of recovered single crystal seeds joined to one another in intimate contact with one another.
7. The method of manufacturing a cast silicon single crystal ingot according to claim 1, further comprising the step of slicing the cast silicon single crystal ingot to a predetermined size.
8. A cast silicon single crystal ingot produced by the method for producing a cast silicon single crystal ingot according to any one of claims 1 to 7.
9. A preparation method of a cast monocrystalline silicon piece is characterized by comprising the following steps:
slicing the cast single crystal silicon ingot of claim 8 to obtain a cast single crystal silicon wafer.
10. A cast single-crystal silicon wafer characterized by being produced by the method for producing a cast single-crystal silicon wafer according to claim 9.
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| CN111364097A (en) * | 2020-04-15 | 2020-07-03 | 晶科能源有限公司 | Monocrystalline silicon seed crystal, silicon ingot, silicon block and silicon wafer of directionally solidified ingot casting, and preparation method and application thereof |
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