CN100590235C - Method for preparing solar grade silicon - Google Patents
Method for preparing solar grade silicon Download PDFInfo
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- CN100590235C CN100590235C CN200810120790A CN200810120790A CN100590235C CN 100590235 C CN100590235 C CN 100590235C CN 200810120790 A CN200810120790 A CN 200810120790A CN 200810120790 A CN200810120790 A CN 200810120790A CN 100590235 C CN100590235 C CN 100590235C
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Abstract
The invention relates to a method for preparing solar grade silicon, which comprises the following steps: firstly, silicon nitride or quartz is used for manufacturing a navicular crucible, wherein, the thickness in the center of the bottom of the crucible is larger than the thickness of the edge of the bottom of the crucible, the thickness of the bottom is smoothly reduced from the center to the edge, and the inner surface of the crucible is evenly coated with a silicon nitride coating; then, the crucible is put in a sintering furnace for sintering; finally, silicon material is put into the crucible, and carries out horizontal zone-melting under vacuum condition by strictly controlling the melting temperature and the zone traveling speed, so as to obtain the silicon material achieving therequirement of solar grade silicon. The method is simple and practicable without pollution, protects the crucible from fracture during the process of horizontal zone-melting refining with high refining efficiency, and can obviously reduce the manufacturing cost.
Description
Technical field
The present invention relates to prepare the method for solar-grade silicon.
Background technology
Silicon is the chief component of current most solar cells.With solar energy converting is that the mechanism of electric energy depends on the inner PN junction structure that forms of silicon chip.PN junction can form by inject N type impurity in P type silicon, and vice versa.
Eighties of last century, used in electronic industry silicon single crystal are to adopt the high purity polycrystalline silicon of improvement Siemens Method or silane thermal decomposition process preparation as raw material, obtain by the molten growth method of vertical pulling or district.And, be with the waste material of silicon in the electronic industry traditionally and expect end to end to originate as main raw for solar cell industry silicon crystal.But photovoltaic industry development in recent years is very fast, supply falls short of demand with silicon for solar cell, has caused the solar-grade silicon market value to experience unprecedentedly soaring from $45/kg to $500/kg.This makes the cost of solar cell improve greatly, has reduced its possibility of being promoted fast.Yet solar cell is so harsh to the requirement of the sila matter concentration electronic industry that is far from, and in general, solar cell is more than 1000 times of electron device such as unicircuit to the degrees of tolerance of impurity in the silicon.So people do not need silicon is purified to the degree (more than 99.9999999%) of electronic-grade, are applied to the making of solar cell again, only need directly silicon to be purified to solar-grade (more than 99.9999%) and get final product, can reduce the cost of solar cell like this.But the technology of this low-cost purified silicon remains a great problem in the world up till now, though there is variety of way to attempt, technology that generally acknowledge, large-scale industrialized production does not also break through.
Zone melting method is a kind of effective means (silicon materials science and technology of purification semiconductor material, Que Duanlin, the Chen Xiuzhi chief editor, press of Zhejiang University, ISBN 7-308-02636-1/TN.053,2000, Hangzhou), its ultimate principle is placed on electromagnetic induction coil around the raw semiconductor, utilize the energising heating,, then coil is moved to other one section from a section of semiconductor source material the semiconductor material partial melting, make the partial melting zone also move to other one section gradually from one section, in moving process,, cause the principle of the zone-refine of branch coagulation phenomena based on impurity different solubility in melt and solid by the process that melts-solidify, impurity is rejected to an end of semiconductor material, thereby reaches the purification purpose of semiconductor material.And repeatedly zone-refine can obtain high-purity semiconductor material.Generally speaking, zone melting technique is divided into the molten and horizontal zone melting of vertical area.Vertical area is molten need to become bar-shaped with raw material preparing, and places perpendicular to horizontal plane, owing to can't use crucible, so relative cost is higher, but the material purity of preparation is higher.And horizontal zone melting, be semiconductor material to be placed on to distinguish in the horizontal crucible melt, owing to can use crucible, make raw-material shape, size, weight not be subjected to a lot of restrictions, simultaneously owing to use crucible, make district molten speed, efficient obviously increase, the cost level that semiconductor material is purified can greatly reduce, and has obtained widespread use in the purification as semiconductor materials such as HpGes.But, for silicon materials, because quartz crucible commonly used is broken easily when horizontal zone melting, so can't utilize horizontal method to come the zone-refine silicon materials.
Summary of the invention
The purpose of this invention is to provide a kind of low cost, prepare the method for solar-grade silicon with horizontal zone melting.
The method for preparing solar-grade silicon of the present invention is characterized in that may further comprise the steps:
1) with silicon nitride or the quartzy slick boat shape of the internal surface crucible of making, the boat of boat shape crucible is as semi-cylindrical shaped, two is 1/4th spheries, and the thickness at crucible bottom center is greater than the thickness at crucible edge, and smoothly successively decreases from the crucible bottom center to crucible edge thickness;
2) the internal surface of crucible equably coating thickness be the silicon nitride layer of 50-300 micron;
3) crucible is put into sintering oven, in 800-1400K temperature sintering 60-400 minute;
4) put into the silicon material in the crucible, carry out horizontal zone melting under vacuum condition, the control temperature of fusion is at 1700K-1900K, and the melting zone rate travel is at 0.6-3mm/min.
Usually, the thickness at boat shape crucible bottom center is 3-12mm, and the thickness at crucible edge is than the little 0.2-1.8mm of thickness of bottom centre.
The invention has the advantages that:
Simple, pollution-free, adopt bottom centre's thickness bigger than edge thickness, and from the crucible bottom center to crucible edge thickness smoothly successively decrease, the boat shape crucible of inner-wall spraying silicon nitride layer, crucible is difficult for breaking in the horizontal zone melting purification process, the purification efficiency height can obviously reduce production costs, and the silicon that purification obtains can reach the requirement of solar-grade silicon.
Description of drawings
Fig. 1 is a boat shape crucible synoptic diagram, a) is front view, b) is vertical view, c) is figure cross section a).
Embodiment
The present invention prepares the used boat shape crucible of solar-grade silicon as shown in Figure 1, and boat is as semi-cylindrical shaped, and two is 1/4th spheries, and the thickness at crucible bottom center is greater than the thickness at crucible edge, and smoothly successively decreases from the crucible bottom center to crucible edge thickness.The thickness at crucible bottom center is 3-12mm, and the thickness at crucible edge is than the little 0.2-1.8mm of thickness of bottom centre.
Embodiment 1
1) with the quartzy slick boat shape of the internal surface crucible of making, the thickness at crucible bottom center is 11mm, and the thickness at edge is 10.3mm;
2) the internal surface of crucible equably coating thickness be 60 microns silicon nitride layer;
3) crucible is put into sintering oven, in 800K temperature sintering 150 minutes;
4) put into the silicon material in the crucible, carry out horizontal zone melting under vacuum condition, the control temperature of fusion is at 1700K, and the melting zone rate travel is at 0.6mm/min.The silicon that purification obtains reaches the requirement of solar-grade silicon.
Embodiment 2
1) with the quartzy slick boat shape of the internal surface crucible of making, the thickness at crucible bottom center is 7.5mm, and the thickness at edge is 6.4mm;
2) the internal surface of crucible equably coating thickness be 300 microns silicon nitride layer;
3) crucible is put into sintering oven, in 1350K temperature sintering 360 minutes;
4) put into the silicon material in the crucible, carry out horizontal zone melting under vacuum condition, the control temperature of fusion is at 1700K, and the melting zone rate travel is at 2.4mm/min.The silicon that purification obtains reaches the requirement of solar-grade silicon.
Embodiment 3
1) make the slick boat shape of internal surface crucible with silicon nitride, the thickness at crucible bottom center is 6mm, and the thickness at edge is 4.5mm;
2) the internal surface of crucible equably coating thickness be 100 microns silicon nitride layer;
3) crucible is put into sintering oven, in 1350K temperature sintering 210 minutes;
4) put into the silicon material in the crucible, carry out horizontal zone melting under vacuum condition, the control temperature of fusion is at 1800K, and the melting zone rate travel is at 2.8mm/min.The silicon that obtains reaches the requirement of solar-grade silicon.
Claims (2)
1. method for preparing solar-grade silicon is characterized in that may further comprise the steps:
1) with silicon nitride or the quartzy slick boat shape of the internal surface crucible of making, the boat of boat shape crucible is as semi-cylindrical shaped, two is 1/4th spheries, and the thickness at crucible bottom center is greater than the thickness at crucible edge, and smoothly successively decreases from the crucible bottom center to crucible edge thickness;
2) the internal surface of crucible equably coating thickness be the silicon nitride layer of 50-300 micron;
3) crucible is put into sintering oven, in 800-1400K temperature sintering 60-400 minute;
4) put into the silicon material in the crucible, carry out horizontal zone melting under vacuum condition, the control temperature of fusion is at 1600K-1800K, and the melting zone rate travel obtains solar-grade silicon at 0.6-3mm/min.
2. the method for preparing solar-grade silicon according to claim 1, the thickness that it is characterized in that the crucible bottom center is 3-12mm, the thickness at crucible edge is than the little 0.2-1.8mm of thickness of bottom centre.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200810120790A CN100590235C (en) | 2008-09-05 | 2008-09-05 | Method for preparing solar grade silicon |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200810120790A CN100590235C (en) | 2008-09-05 | 2008-09-05 | Method for preparing solar grade silicon |
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| Publication Number | Publication Date |
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| CN101372759A CN101372759A (en) | 2009-02-25 |
| CN100590235C true CN100590235C (en) | 2010-02-17 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN200810120790A Expired - Fee Related CN100590235C (en) | 2008-09-05 | 2008-09-05 | Method for preparing solar grade silicon |
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Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2012083480A1 (en) * | 2010-12-20 | 2012-06-28 | Epro Development Limited | Method and apparatus for producing pure silicon |
| CN102225837B (en) * | 2011-05-08 | 2013-01-23 | 江苏润弛太阳能材料科技有限公司 | Manufacture method of spray-free fused quartz crucible used for polycrystalline silicon cast ingots |
| CN102249523B (en) * | 2011-05-08 | 2012-10-31 | 江苏润弛太阳能材料科技有限公司 | Method for manufacturing spray-free fused quartz crucible for polycrystalline silicon cast ingot |
| CN108707964A (en) * | 2018-04-13 | 2018-10-26 | 中国电子科技集团公司第十研究所 | Melt crucible and material ingot in the area for being used to prepare molecular beam epitaxy beam source material ingot |
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