CN101597791A - Directional solidification casting polycrystalline silicon of nitrating and preparation method thereof - Google Patents
Directional solidification casting polycrystalline silicon of nitrating and preparation method thereof Download PDFInfo
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- CN101597791A CN101597791A CNA2009100999950A CN200910099995A CN101597791A CN 101597791 A CN101597791 A CN 101597791A CN A2009100999950 A CNA2009100999950 A CN A2009100999950A CN 200910099995 A CN200910099995 A CN 200910099995A CN 101597791 A CN101597791 A CN 101597791A
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- polycrystalline silicon
- nitrogen
- nitrating
- casting polycrystalline
- directional solidification
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Abstract
The invention discloses directional solidification casting polycrystalline silicon of a kind of nitrating and preparation method thereof, utilize cheap nitrogen to replace expensive argon gas, realize low-cost directional solidification casting polycrystalline silicon as shielding gas; Simultaneously, owing under nitrogen atmosphere, melt silicon and casting, be implemented in and mix nitrogen in the polysilicon, obtain the nitrating casting polycrystalline silicon, improved the physical strength of casting polycrystalline silicon, be used for solar cell and can be cut into thinner silicon chip, thus the production cost of reduction solar cell.It is 1 * 10 that casting polycrystalline silicon of the present invention contains concentration
15～1 * 10
17/ cm
3Boron, gallium and phosphorus, also containing concentration is 1 * 10
13～5 * 10
15/ cm
3Nitrogen.
Description
Technical field
The present invention relates to technical field of semiconductors, relate in particular to directional solidification casting polycrystalline silicon of a kind of nitrating and preparation method thereof.
Background technology
Sun power is inexhaustible clean energy, utilizes the light transfer characteristic of semiconductor material, is prepared into solar cell, sun power can be transformed into electric energy.
Directional solidification casting polycrystalline silicon is a kind of main raw of solar cell, and influencing the widely used major obstacle of solar cell is that cost is higher.The general high-purity argon gas that adopts is as protection gas in the casting polycrystalline silicon manufacturing processed.Major cause is because argon gas is a kind of rare gas element, it not only not can with melt pasc reaction, and can intercept other active higher gases that may exist in the furnace chamber and melt pasc reaction, thereby guarantee the crystalline quality.But the preparation cost of high-purity argon gas occupies certain ratio than higher in the manufacturing cost of casting polycrystalline silicon.Thereby, in the prior art in the commonly used argon gas atmosphere casting polycrystalline silicon expensive limited being extensive use of of solar cell greatly, seek a kind of under protective atmosphere cheaply casting polycrystalline silicon be necessary.
Summary of the invention
The invention provides a kind of directional solidification casting polycrystalline silicon of nitrating, its physical strength height can be cut into thinner silicon chip and be applied to solar cell, reduces the manufacturing cost of solar cell.
A kind of directional solidification casting polycrystalline silicon of nitrating, containing concentration is 1 * 10
15～1 * 10
17/ cm
3Boron, gallium or phosphorus, also containing concentration is 1 * 10
13～5 * 10
15/ cm
3Nitrogen.
The present invention also provides the preparation method of the directional solidification casting polycrystalline silicon of above-mentioned nitrating, replaces argon gas with high costs with nitrogen, has solved the high problem of existing directional solidification casting polycrystalline silicon production cost.
The preparation method of the directional solidification casting polycrystalline silicon of above-mentioned nitrating may further comprise the steps:
(1) polycrystalline silicon raw material is placed in the crucible, the charging capacity of doping content calculating according to target adds electroactive adulterant, shove charge;
Wherein, described electroactive adulterant is boron, gallium or phosphorus; The concentration of electroactive adulterant in the target product that described target doping content will prepare for the present invention, among the present invention, the target doping content of electroactive adulterant is 1 * 10
15～1 * 10
17/ cm
3
(2) furnace chamber is vacuumized the back and feed nitrogen, nitrogen gas pressure is 5～200Torr, and flow is 1～200L/min; Polycrystalline silicon raw material and electroactive adulterant be heated to be melted into liquid fully and obtain silicon melt, Heating temperature is more than the silicon fusing point, preferred 1420～1450 ℃, both can melt polycrystalline silicon raw material and electroactive adulterant, and do not produce too high energy consumption again.
(3) promote stay-warm case in the stove with the speed of 1～4mm/min, cool off the crucible bottom simultaneously, make the heat exchange of silicon melt mainly occur in crucible bottom, like this, silicon melt from the bottom upwards gradually directional freeze form the polysilicon of nitrating.The process of this directionally solidified casting monocrystalline silicon is also carried out in nitrogen atmosphere.
Among the present invention, regulate thermal field by stay-warm case position in cooling crucible bottom and the adjustment stove, (the crystalline direction of growth vertically upward to form unidirectional hot-fluid, direction of heat flow is vertically downward) carry out directional freeze, only there is certain axial-temperature gradient in this process at the solid-liquid interface place, and, thereby the growth of realization from bottom to up casting monocrystalline silicon less at horizontal areal temperatuer gradient.Usually, take to be blown into cooling gas or to feed water coolant to cool off the crucible bottom in crucible bottom.Wherein, cooling gas can adopt safety, cheap, the gas commonly used that is easy to get, general cooling rare gas element or the cool nitrogen of adopting.
Among the present invention, melting the nitrogen that feeds in silicon and the castingprocesses, preferably to adopt purity be 99.999～99.9999% nitrogen, can guarantee can not cross the low impurity effect quality product of introducing because of purity, unlikely again because of using highly purified nitrogen to increase cost.Can control the amount of nitrating by regulating nitrogen gas pressure and flow.
The inventive method adopts cheap high pure nitrogen to replace high-purity argon gas as protection gas; reduced the manufacturing cost of casting polycrystalline silicon; simultaneously; when feeding nitrogen is used for melting silicon and castingprocesses as protection gas; nitrogen can with melt pasc reaction and enter silicon melt; also can in castingprocesses, mix, thus the directional solidification casting polycrystalline silicon of acquisition nitrating.In the directional solidification casting polycrystalline silicon of nitrating, the nitrogen that mixes can pinning silicon in dislocation, can strengthen casting polycrystalline silicon physical strength, reduce the density of dislocation, the life-span of having improved silicon chip, make silicon chip can cut thinlyyer, be applied to significantly to reduce cost in the solar cell.
Embodiment
Embodiment 1
The polycrystalline silicon raw material of 240kg is placed crucible, mix the doping agent boron of 20mg, shove charge.Then furnace chamber being evacuated and feeding purity is 99.999% nitrogen, and nitrogen gas pressure is 10Torr, and the flow of nitrogen is 100L/min.Polycrystalline silicon raw material and boron are heated to 1420 ℃ gradually, form silicon melt until melting fully.Promote stay-warm case with the speed of 2mm/min then, be blown into the cooling helium in crucible bottom simultaneously, make the heat exchange of silicon melt mainly occur in crucible bottom, like this, silicon melt from the bottom upwards gradually directional freeze form doped polysilicon.Boron concentration is 6 * 10 in the doped polysilicon that forms
15/ cm
3, nitrogen concentration is 1 * 10
15/ cm
3All take nitrogen protection in whole casting polycrystalline silicon process, the time is 72 hours.
Present embodiment directional solidification casting polycrystalline silicon manufacturing cost under 99.999% nitrogen protection than the argon shield of same purity under the same conditions under directional solidification casting polycrystalline silicon to save 50000 yuan; U-PCD records its minority carrier life time under passive surface compound situation not be 3 microseconds, can be used for the preparation of solar cell.
Embodiment 2
The polycrystalline silicon raw material of 450kg is placed crucible, mix the doping agent boron of 20mg, realize shove charge.The feeding purity that then furnace chamber is evacuated is 99.9999% nitrogen, and polycrystalline silicon raw material and boron are heated to 1450 ℃ gradually, forms silicon melt until melting fully, and wherein nitrogen gas pressure is 100Torr, and the flow of nitrogen is 10L/min.Promote stay-warm case in the stove with the speed of 4mm/min then, feed water coolant in crucible bottom simultaneously, make the heat exchange of silicon melt mainly occur in crucible bottom, like this, silicon melt from the bottom upwards gradually directional freeze form doped polysilicon.Boron concentration is 6 * 10 in the doped polysilicon that forms
15/ cm
3, nitrogen concentration is 5 * 10
15/ cm
3All take nitrogen protection in whole casting polycrystalline silicon process, the time is 56 hours.
In the present embodiment; directional solidification casting polycrystalline silicon manufacturing cost under 99.9999% nitrogen protection than the argon shield of same purity under the same conditions under directional solidification casting polycrystalline silicon to save 20000 yuan; u-PCD records its minority carrier life time under passive surface compound situation not be 3.5 microseconds, can be used for the preparation of solar cell.
Claims (3)
1, a kind of directional solidification casting polycrystalline silicon of nitrating is characterized in that: containing concentration is 1 * 10
15～1 * 10
17/ cm
3Boron, gallium or phosphorus, also containing concentration is 1 * 10
13～5 * 10
15/ cm
3Nitrogen.
2, the preparation method of the directional solidification casting polycrystalline silicon of nitrating as claimed in claim 1 may further comprise the steps:
(1) polycrystalline silicon raw material is placed in the crucible, add electroactive adulterant, shove charge; Wherein, described electroactive adulterant is boron, gallium or phosphorus;
(2) furnace chamber is vacuumized the back and feed nitrogen, nitrogen gas pressure is 5～200Torr, and flow is 1～200L/min; Polycrystalline silicon raw material and electroactive adulterant are heated to thawing fully, and Heating temperature is more than the silicon fusing point;
(3) speed with 1～4mm/min promotes stay-warm case in the stove, cools off the crucible bottom simultaneously, directional freeze, the directional solidification casting polycrystalline silicon of formation nitrating.
3, preparation method as claimed in claim 2 is characterized in that: in the step (2), described Heating temperature is 1420～1450 ℃.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2009100999950A CN101597791A (en) | 2009-06-24 | 2009-06-24 | Directional solidification casting polycrystalline silicon of nitrating and preparation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2009100999950A CN101597791A (en) | 2009-06-24 | 2009-06-24 | Directional solidification casting polycrystalline silicon of nitrating and preparation method thereof |
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|---|---|
| CN101597791A true CN101597791A (en) | 2009-12-09 |
Family
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|---|---|---|---|
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101845666A (en) * | 2010-06-03 | 2010-09-29 | 王敬 | N-doped crystalline silicon and preparation method thereof |
| CN101864593A (en) * | 2010-06-03 | 2010-10-20 | 王敬 | N-doped crystalline silicon and preparation method thereof |
| CN101935867A (en) * | 2010-09-17 | 2011-01-05 | 浙江大学 | Method for growing large-grain cast multicrystalline silicon |
| CN101935868A (en) * | 2010-09-17 | 2011-01-05 | 浙江大学 | Crucible for growing large-grain cast polycrystalline silicon |
-
2009
- 2009-06-24 CN CNA2009100999950A patent/CN101597791A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101845666A (en) * | 2010-06-03 | 2010-09-29 | 王敬 | N-doped crystalline silicon and preparation method thereof |
| CN101864593A (en) * | 2010-06-03 | 2010-10-20 | 王敬 | N-doped crystalline silicon and preparation method thereof |
| CN101845666B (en) * | 2010-06-03 | 2013-08-28 | 王敬 | N-doped crystalline silicon and preparation method thereof |
| CN101935867A (en) * | 2010-09-17 | 2011-01-05 | 浙江大学 | Method for growing large-grain cast multicrystalline silicon |
| CN101935868A (en) * | 2010-09-17 | 2011-01-05 | 浙江大学 | Crucible for growing large-grain cast polycrystalline silicon |
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Open date: 20091209 |