CN102021645A - Method for preparing polycrystalline silicon ingot with directional solidification microstructure - Google Patents
Method for preparing polycrystalline silicon ingot with directional solidification microstructure Download PDFInfo
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- CN102021645A CN102021645A CN 201010609932 CN201010609932A CN102021645A CN 102021645 A CN102021645 A CN 102021645A CN 201010609932 CN201010609932 CN 201010609932 CN 201010609932 A CN201010609932 A CN 201010609932A CN 102021645 A CN102021645 A CN 102021645A
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Abstract
The invention relates to a method for preparing a polycrystalline silicon ingot with directional solidification microstructure, relating to a method for producing the polycrystalline silicon ingot so as to solve the problem of low purity of polycrystalline silicon ingots caused by the pollution of sleeve inner wall on the polycrystalline silicon because that the existing polycrystalline silicon ingots are produced in a ceramic or graphite sleeve. The method comprises the following steps: 1, leaking 25g of silicon particles on a graphite base; 2, vacuumizing; 3, filling argon gas into a vacuum chamber; 4, melting the silicon particles in a cold crucible by using an induction coil; 5, adding silicon particles into the cold crucible to form a melt hump of the silicon particle, and then stopping a stepping motor, and preserving the temperature for 8 minutes; 6, driving a pulling rod to move downward, and starting the stepping motor so as to enable the silicon particles in a graphite tube to be fed into the cold crucible, wherein a cooler provides compulsive cold for the melted silicon particles so as to enable the melted silicon particles to form columnar crystals with the directional solidification microstructure; and 7, processing and removing the polycrystal layers of the polycrystalline ingots to obtain the polycrystalline silicon ingots with the directional solidification microstructure. The method is used for preparing the polycrystalline ingots.
Description
Technical field
The present invention relates to a kind of preparation method of polycrystal silicon ingot.
Background technology
Silicon solar cell in the market mainly contains silicon single crystal, polysilicon and non-crystalline silicon three major types: monocrystaline silicon solar cell has obtained using widely with characteristics such as its efficiency of conversion height (24.5%), steady qualities in the international market, but silicon single crystal is to the purity requirement height (99.999999999%) of raw material, therefore, monocrystalline silicon production cost height has restricted the application of silicon single crystal.Polysilicon solar cell is with its efficiency of conversion higher (19.8%), stable performance and cost are moderate and be used widely, polycrystal silicon cell is low to the purity requirement of raw material, the source channel of raw material is also comparatively wide, can form by ingot casting, be fit to large-scale commercial applications production, the dominant position of occuping market.Non-crystal silicon solar cell efficiency of conversion lower (14.5%), performance are extremely unstable, and cell decay is fast, and its application has been subjected to restriction.The E.Ehret of France and people such as F.Durand are applied to the polysilicon continuous casting with the continuous casting electromagnetic technology, and it is suitable substantially that the polysilicon that this method is made decide foreign matter content, and cost is low, still have crystal defect, polycrystal silicon ingot organize the column crystal that is not directional freeze.Directional freeze is that metal (or crystal class material) can solidify or the crystalline process along the fixed growth direction under control foundry goods internal heat transfer, mass transfer and mobile condition.The tissue signature of metal is the one group parallel column crystal parallel with the heat of solidification flow path direction after the directional freeze.Directional freeze is at the special material processing technique that satisfies under unidirectional heat and the mass transfer primary condition.The preparation of directional freeze polycrystal silicon ingot at present mainly is to be to carry out in pottery (corundum) about 100mm or the graphite sleeve at diameter, and sleeve lining produces grain silicon and pollutes, so that influences the purity of silicon ingot at last.
Summary of the invention
The preparation that the objective of the invention is for solving existing polycrystal silicon ingot mainly is to carry out in pottery or graphite sleeve, sleeve lining produces polysilicon and pollutes, cause the low problem of purity of polycrystal silicon ingot, a kind of preparation method with oriented freezing organization polycrystal silicon ingot is provided.
Method of the present invention realizes by following steps:
The upper surface of step 1, graphite base is arranged on the upper surface 20mm～35mm place apart from cold crucible, and hopper is filled grain silicon, and the grain silicon of 20g～30g on the upper surface of the graphite base that bleeds earlier;
Step 2, utilize vacuum pump that vacuum chamber is vacuumized, the vacuum tightness that makes vacuum chamber is 0.05Pa～0.1Pa;
Step 3, charge into the argon gas of 300Pa～400Pa to vacuum chamber;
Step 4, ruhmkorff coil feed single phase alternating current, and power is 45KW～55KW, by ruhmkorff coil the grain silicon induction heating in the cold crucible are also melted fully;
Step 6, startup displacement electric motor driving pull bar move downward with the speed of 1mm/min～2mm/min, start stepper-motor simultaneously, make the grain silicon in the carbon tube continuously reinforced in cold crucible with the speed of 1.73g/min～5.19g/min, water cooler below the cold crucible provides cold by force for the grain silicon of fusing simultaneously, make the grain silicon of fusing form column crystal with oriented freezing organization, after treating that the graphite base moves down 10mm～15mm, be the column crystal silicon ingot of desired length;
The skin of step 7, column crystal silicon ingot has the polycrystal layer of 1mm～2mm, and is outer inner for being parallel to the column crystal of pull bar direction, is after polycrystal layer processing is removed to have the oriented freezing organization polycrystal silicon ingot.
The present invention has the following advantages: one, the polycrystal silicon ingot of the inventive method preparation is to be prepared from vacuum chamber, and the material of cold crucible is red copper, and therefore, the polycrystal silicon ingot of the inventive method preparation is pollution-free; The polycrystal silicon ingot that utilizes the inventive method to produce has the column crystal of oriented freezing organization, and the column crystal growth is continuous, column crystal is big, and the width of column crystal is 1mm～2.8mm, and column crystal runs through the height of polycrystal silicon ingot, therefore, the polycrystal silicon ingot purity height of the inventive method preparation.Two, the polycrystal silicon ingot of the inventive method preparation has the advantage of environmental protection, low-carbon (LC).Three, the polycrystal silicon ingot with directional freeze of the inventive method preparation is specially adapted to the requirement of solar-grade polysilicon to purity.
Description of drawings
Fig. 1 is a kind of structure master's sectional view with preparation facilities of directional freeze polycrystal silicon ingot of realizing the inventive method, Fig. 2 is the A-A sectional view of Fig. 1, Fig. 3 is structure master's sectional view of cold crucible 8, and Fig. 4 is the B-B sectional view of Fig. 3, and Fig. 5 is the I partial enlarged drawing of Fig. 4.(Reference numeral among the figure is: body of heater 1, vacuum chamber 2, vacuum pump 3, water cooler 4, pull bar 5, displacement motor 6, graphite base 7, cold crucible 8, Fang Huanzhuan rising pipe 9, water outlet takes over 10, first nut 11, tank inlet pipe 12, Fang Huanzhuan water inlet pipe 13, water inlet takes over 14, second nut 15, radiator drain 16, ruhmkorff coil 17, carbon tube 18, back up pad 19, surge hopper 20, housing 21, screw rod 22, shaft coupling 23, adjustable transmission 24, stepper-motor 25, hopper 26, upper semi-body 8-1, lower semi-body 8-2, insulated enclosure material 8-3, the cross section is petal-like cylinder 8-4, limbers 8-5 and vertical blind hole 8-6).
Embodiment
Embodiment one: in conjunction with Fig. 1 and Fig. 2 present embodiment is described, present embodiment realizes by following steps:
The upper surface of step 1, graphite base 7 is arranged on the upper surface 20mm～35mm place apart from cold crucible 8, and hopper 26 is filled grain silicon, and the grain silicon of 20g～30g on the upper surface of the graphite base 7 that bleeds earlier;
Step 2, utilize vacuum pump 3 that vacuum chamber 2 is vacuumized, the vacuum tightness that makes vacuum chamber 2 is 0.05Pa～0.1Pa;
Step 3, charge into the argon gas of 300Pa～400Pa to vacuum chamber 2;
Step 4, ruhmkorff coil 17 feed single phase alternating current, and power is 45KW～55KW, by ruhmkorff coil 17 the grain silicon induction heating in the cold crucible 8 are also melted fully;
Step 6, startup displacement motor 6 driving pull bars 5 move downward with the speed of 1mm/min～2mm/min, start stepper-motor 25 simultaneously, make the grain silicon in the carbon tube 18 continuously reinforced in cold crucible 8 with the speed of 1.73g/min～5.19g/min, water cooler 4 below the cold crucible 8 provides cold by force for the grain silicon of fusing simultaneously, make the grain silicon of fusing form column crystal with oriented freezing organization, after treating that graphite base 7 moves down 10mm～15mm, be the column crystal silicon ingot of desired length;
The skin of step 7, column crystal silicon ingot has the polycrystal layer of 1mm～2mm, and is outer inner for being parallel to the column crystal of pull bar direction, is after polycrystal layer processing is removed to have the oriented freezing organization polycrystal silicon ingot.
The present invention is realized by induction heating, electromagnetic confinement and three processes of column crystal growth; Aspect induction heating, electromagnetic induction heating graphite base 7, graphite base 7 preheating particulate silicon, grain silicon can be by directly extremely fusing of induction heating when certain temperature; Aspect electromagnetic confinement, high frequency magnetic field is with the raw material induction melting, and formation hump, control hump height by screw rod 22 and pull bar 5 speed, increasing ruhmkorff coil 17 power increases the melt overheat degree, and reduce with the inwall contact area of cold crucible 8, reduce the scull effect, make melt be in stable form; Aspect the column crystal growth, because the cooling of 8 times aerators 4 of cold crucible, form big temperature gradient distribution, electromagnetic field stirs molten matter is evenly distributed, and the soft Contact Effect of electromagnetic confinement makes the side direction heat radiation be inhibited, induction heating makes silicon grain melt, by long preheating initial crystal grain is slowly grown up, form straight solid-liquid interface at last, in cold-crucible, obtain free of contamination directional freeze at last.
Embodiment two: in conjunction with Fig. 1 present embodiment is described, the material of the cold crucible 8 in the step 1 of present embodiment is a red copper.The red copper grain silicon does not produce pollution.Other step is identical with embodiment one.
Embodiment three: in conjunction with Fig. 1 present embodiment is described, the grain silicon of 25g on the upper surface of the graphite base 7 that bleeds earlier in the step 1 of present embodiment.Other step is identical with embodiment one.
Embodiment four: in conjunction with Fig. 1 present embodiment is described, the vacuum tightness of the vacuum chamber 2 in the step 2 of present embodiment is 0.08Pa.Other step is identical with embodiment one.
Embodiment five: in conjunction with Fig. 1 present embodiment is described, charges into the argon gas of 350Pa in the step 3 of present embodiment to vacuum chamber 2.Other step is identical with embodiment one.
Embodiment six: in conjunction with Fig. 1 present embodiment is described, the line of the ruhmkorff coil 17 in the step 4 of present embodiment directly is Φ 8mm～Φ 12mm, and the number of turn of ruhmkorff coil 17 is 4 circles.This design makes that the interior hump height that forms of crucible is suitable, helps the smooth implementation of continuous fusion-cast process.Other step is identical with embodiment one.
Embodiment seven: in conjunction with Fig. 1 present embodiment is described, the power in the step 4 of present embodiment is 50KW.Other step is identical with embodiment one or six.
Embodiment eight: in conjunction with Fig. 1 present embodiment is described, the grain silicon behind the melt hump that in cold crucible 8, forms in the step 5 of present embodiment, soaking time is 15min.Other step is identical with embodiment one.
Embodiment nine: in conjunction with Fig. 1 present embodiment is described, the feed rate of the grain silicon in the speed that the pull bar 5 in the step 6 of present embodiment moves downward and the carbon tube 18 is consistent.Other step is identical with embodiment one.
Embodiment ten: in conjunction with Fig. 1 present embodiment is described, graphite base 7 moves down 12mm in the step 6 of present embodiment.Other step is identical with embodiment one or nine.
Claims (10)
1. preparation method with oriented freezing organization polycrystal silicon ingot, it is characterized in that: described method realizes by following steps:
The upper surface of step 1, graphite base (7) is arranged on the upper surface 20mm～35mm place apart from cold crucible (8), and hopper (26) is filled grain silicon, and the grain silicon of 20g～30g on the upper surface of graphite base (7) of bleeding earlier;
Step 2, utilize vacuum pump (3) that vacuum chamber (2) is vacuumized, the vacuum tightness that makes vacuum chamber (2) is 0.05Pa～0.1Pa;
Step 3, charge into the argon gas of 300Pa～400Pa to vacuum chamber (2);
Step 4, ruhmkorff coil (17) feed single phase alternating current, and power is 45KW～55KW, by ruhmkorff coil (17) the grain silicon induction heating in the cold crucible (8) are also melted fully;
Step 5, startup stepper-motor (25) continuously add grain silicon in cold crucible (8), behind the formation grain silicon melt hump, stop stepper-motor (25), insulation 8min～24min;
Step 6, startup displacement motor (6) driving pull bar (5) move downward with the speed of 1mm/min～2mm/min, start stepper-motor (25) simultaneously, make the grain silicon in the carbon tube (18) continuously reinforced in cold crucible (8) with the speed of 1.73g/min～5.19g/min, water cooler (4) below the cold crucible (8) provides cold by force for the grain silicon of fusing simultaneously, make the grain silicon of fusing form column crystal with oriented freezing organization, after treating that graphite base (7) moves down 10mm～15mm, be the column crystal silicon ingot of desired length;
The skin of step 7, column crystal silicon ingot has the polycrystal layer of 1mm～2mm, and is outer inner for being parallel to the column crystal of pull bar direction, is after polycrystal layer processing is removed to have the oriented freezing organization polycrystal silicon ingot.
2. according to the described a kind of preparation method with oriented freezing organization polycrystal silicon ingot of claim 1, it is characterized in that: the material of the cold crucible in the step 1 (8) is a red copper.
3. according to the described a kind of preparation method of claim 1, it is characterized in that: the grain silicon of 25g on the upper surface of graphite base (7) of bleeding earlier in the step 1 with oriented freezing organization polycrystal silicon ingot.
4. according to the described a kind of preparation method with oriented freezing organization polycrystal silicon ingot of claim 1, it is characterized in that: the vacuum tightness of the vacuum chamber in the step 2 (2) is 0.08Pa.
5. according to the described a kind of preparation method of claim 1, it is characterized in that: the argon gas that charges into 350Pa in the step 3 to vacuum chamber (2) with oriented freezing organization polycrystal silicon ingot.
6. according to the described a kind of preparation method with oriented freezing organization polycrystal silicon ingot of claim 1, it is characterized in that: the line of the ruhmkorff coil in the step 4 (17) directly is Φ 8mm～Φ 12mm, and the number of turn of ruhmkorff coil (17) is 4 circles.
7. according to claim 1 or 6 described a kind of preparation methods with oriented freezing organization polycrystal silicon ingot, it is characterized in that: the power in the step 4 is 50KW.
8. according to the described a kind of preparation method with oriented freezing organization polycrystal silicon ingot of claim 1, it is characterized in that: the grain silicon behind the melt hump that forms in cold crucible (8) in the step 5, soaking time is 15min.
9. according to the described a kind of preparation method with oriented freezing organization polycrystal silicon ingot of claim 1, it is characterized in that: the feed rate of the grain silicon in the speed that the pull bar in the step 6 (5) moves downward and the carbon tube (18) is consistent.
10. according to claim 1 or 9 described a kind of preparation methods with oriented freezing organization polycrystal silicon ingot, it is characterized in that: graphite base (7) moves down 12mm in the step 6.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102797039A (en) * | 2012-08-21 | 2012-11-28 | 北京科技大学 | Device and method for producing ultrapure polysilicon ingot by electromagnetic method |
| CN104195635A (en) * | 2014-09-28 | 2014-12-10 | 哈尔滨工业大学 | Large-width columnar crystal silicon ingot preparation method by adopting seed crystal method |
| CN114751415A (en) * | 2022-04-13 | 2022-07-15 | 武汉理工大学 | Device and method for purifying industrial silicon by electromagnetic semi-continuous directional solidification |
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| EP1930483A1 (en) * | 2005-08-19 | 2008-06-11 | Sumco Solar Corporation | Silicon electromagnetic casting apparatus and method for operating said apparatus |
| US20080179037A1 (en) * | 2006-12-25 | 2008-07-31 | Mitsuo Yoshihara | Casting method of silicon ingot and cutting method of the same |
| CN101377010A (en) * | 2007-08-30 | 2009-03-04 | 上海太阳能工程技术研究中心有限公司 | Device and method for manufacturing solar grade polysilicon |
| CN101479410A (en) * | 2006-06-23 | 2009-07-08 | Rec斯坎沃佛股份有限公司 | Method and crucible for direct solidification of semiconductor grade multi-crystalline silicon ingots |
| CN101602506A (en) * | 2009-07-03 | 2009-12-16 | 锦州市三特真空冶金技术工业有限公司 | A kind of production method of high purity polycrystalline silicon and production equipment |
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2010
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| EP1930483A1 (en) * | 2005-08-19 | 2008-06-11 | Sumco Solar Corporation | Silicon electromagnetic casting apparatus and method for operating said apparatus |
| CN101479410A (en) * | 2006-06-23 | 2009-07-08 | Rec斯坎沃佛股份有限公司 | Method and crucible for direct solidification of semiconductor grade multi-crystalline silicon ingots |
| US20080179037A1 (en) * | 2006-12-25 | 2008-07-31 | Mitsuo Yoshihara | Casting method of silicon ingot and cutting method of the same |
| CN101377010A (en) * | 2007-08-30 | 2009-03-04 | 上海太阳能工程技术研究中心有限公司 | Device and method for manufacturing solar grade polysilicon |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102797039A (en) * | 2012-08-21 | 2012-11-28 | 北京科技大学 | Device and method for producing ultrapure polysilicon ingot by electromagnetic method |
| CN104195635A (en) * | 2014-09-28 | 2014-12-10 | 哈尔滨工业大学 | Large-width columnar crystal silicon ingot preparation method by adopting seed crystal method |
| CN114751415A (en) * | 2022-04-13 | 2022-07-15 | 武汉理工大学 | Device and method for purifying industrial silicon by electromagnetic semi-continuous directional solidification |
| CN114751415B (en) * | 2022-04-13 | 2024-01-16 | 武汉理工大学 | Device and method for purifying industrial silicon by electromagnetic semicontinuous directional solidification |
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