CN101850975A - Method for purifying silicon by removing phosphorus and metal impurities - Google Patents
Method for purifying silicon by removing phosphorus and metal impurities Download PDFInfo
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- CN101850975A CN101850975A CN200910048704A CN200910048704A CN101850975A CN 101850975 A CN101850975 A CN 101850975A CN 200910048704 A CN200910048704 A CN 200910048704A CN 200910048704 A CN200910048704 A CN 200910048704A CN 101850975 A CN101850975 A CN 101850975A
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Abstract
The invention relates to a method for purifying silicon by removing phosphorus and metal impurities, which comprises the following steps of: purifying the inside of an enclosed purifying oven, and heating to melt metal silicon in a graphite crucible of the enclosed purifying oven; blowing preheated O2 and Ar mixed gas to metal silicon solution in a molten state; stopping blowing in the O2 and Ar mixed gas, and quenching the bottom of the silicon solution to directionally solidify the silicon solution from the bottom up; and taking a silicon ingot out of the oven, cutting off the periphery and heat and tail to complete the purification, and obtaining high-purity polycrystalline silicon. Compared with the prior art, the silicon is heated to be molten into a liquid state through DC arc discharge, and simultaneously the preheated O2 and Ar mixed gas is blown to the bottom of the silicon solution to realize the stirring function, so the impurities such as phosphorus with high volatilization factor are removed; and when the stirring time reaches a set value, the silicon solution is directionally solidified from the bottom up, and the purification of the silicon by removing the phosphorus and metals is completed. The method for purifying the silicon has the advantages of low cost, simple process and no environmental pollution, improves the performance of the silicon material, and is easy for industrial production.
Description
Technical field:
The present invention relates to a kind of silicon purification techniques, more specifically to a kind of method of removing the purified silicon of phosphorus and metallic impurity.
Background technology:
The production and the application of fast-developing polysilicon solar cell increase severely the requirement of silicon materials, and consumption is huge.By the present production technology level of China's photovoltaic industry, if produce the 1MW polysilicon solar cell, the thickness of considering silicon chip then need consume 10t left and right sides silicon materials about 200 μ m, with the tempo of present polysilicon solar cell, be far longer than the deliverability of China's silicon materials.Therefore, the production and supply problem of making great efforts and researching and solving silicon materials, it is important solution route that solar energy level silicon is produced in research and development.Because the foreign matter content of metallurgical grade silicon is too high, can not form the product p-n junction, as manage it is purified with simple chemistry or physical method, enable to be used to make solar cell, then will reduce battery cost greatly.Purposive for this reason, selectively to remove the intrinsic contaminants that metallurgy method itself brings be the major issue of physics method purifying solar energy grade silicon material.The method of present reduction phosphorus content is by vaporization at high temperature and directional freeze, and removes to reduce phosphorus content by the method for heating evaporation merely, because liquid level is limited, whole silicon liquid can not get sufficient volatilization, and its effect is very limited.
Summary of the invention:
The objective of the invention is to provide that a kind of manufacture craft is simple at the prior art weak point, the method for the purified silicon of low cost, high-level efficiency, pollution-free removal phosphorus and metallic impurity
The objective of the invention is to realize by following measure: a kind of method of removing the purified silicon of phosphorus and metallic impurity, its special character is, may further comprise the steps:
Step is poly-1, with the sealed type furnace purge of purifying, the Pure Silicon Metal in the heating and melting sealed type purification furnace plumbago crucible;
Step 2 is to the O of the Pure Silicon Metal solution blowing preheated that is molten state
2With the Ar mixed gas;
Step 3 stops to be blown into O
2With the Ar mixed gas,, make it upwards carry out directional freeze from the bottom by the bottom quenching of silicon liquid;
Described step 1 is the sealed type furnace purge of purifying, and described purification is for to vacuumizing the feeding argon gas in the purification furnace, and then vacuumizes the feeding argon gas, and repeated multiple times makes to remain in the purification furnace in the high-purity argon gas state, and the purity of argon gas is greater than 99.999%.
Described step 1 heating and melting is for being fused into liquid state by direct current arc discharge heating silicon, and the Pure Silicon Metal liquid temp remains on more than 1500 ℃.
The positive electrode of the discharge of direct current arc described in the abovementioned steps is that the graphite of crucible protects holder, and negative potential is the discharge electrode with a certain distance from silicon liquid level, and arc-over directly acts on the liquid-state silicon surface.
Described certain distance is set at described in the abovementioned steps: 2-50mm.
The internal surface of described step 1 plumbago crucible covers and is coated with one deck silicon nitride, and the thickness of coating is 0.5-3mm.
Described step 2 preheating O
2With the preheating temperature of Ar mixed gas be more than 1600 ℃.
Described step 2 mixed gas O
2Be respectively 0-90% and 10-100% with the concentration of Ar, purity is greater than 99.999%.
Described step 3 silicon liquid bottom quenching is a movable thermal insulation layer of removing the plumbago crucible bottom, by the heat absorption of the water coolant in the copper pipe, makes the crucible bottom abrupt temperature drop.
Described step 3 directional freeze is that silicon liquid at first solidifies in the bottom, reduces the power of direct supply simultaneously, and the control surface temperature is upwards carried out directional freeze by the bottom.
Compared with prior art, owing to adopted the method for the purified silicon of removal phosphorus that the present invention proposes and metallic impurity, be fused into liquid state by direct current arc discharge heating silicon, and make the arc-over directly act on the liquid-state silicon surface, the O of preheating is blown in the bottom simultaneously
2Realize stirring action with Ar, allow have the high Impurity removals such as phosphorus of bringing into play coefficient; After churning time reaches set(ting)value,, make it upwards carry out directional freeze from the bottom, finished the purification that the silicon dephosphorization is removed metal the bottom quenching of silicon liquid.The present invention is that a kind of low cost, technology are simple, the non-environmental-pollution problem, be easy to manufacture craft and making method that the silicon of industrialization is purified, and it has improved the performance of silicon materials, has very large pushing effect for the development of silicon materials and solar cell.
Description of drawings:
Fig. 1 adds heat abstraction phosphorus synoptic diagram for the direct current arc discharge.
Illustrate among the figure: 1-handles back gas exhausting pipeline; The 2-environment-friendly disposal system; 3-environmental protection treatment liquid; 4-input environmental protection treatment pipeline; The 5-pump; 6-carbon fiber reverberation protective guard; 7-is incubated thermal insulation layer; The 8-plumbago crucible; 9-is blown into O
2With the Ar pipeline; 10-water cooling copper pipe; The movable insulation layer of 11-; 12-graphite protects the double adjustable direct supply of electrode 13-of holder; 14-arc-over negative electrode; The 15-liquid-state silicon; The 16-switch.
Embodiment:
Below in conjunction with accompanying drawing embodiment is elaborated:
Step 1 of the present invention: with the sealed type furnace purge of purifying, described purification is for to vacuumizing the feeding argon gas in the purification furnace, and then vacuumizes the feeding argon gas, and repeated multiple times makes to remain in the purification furnace in the high-purity argon gas state, and the purity of argon gas is greater than 99.999%.This is because have a large amount of impurity particles in the air, so silicon liquid must be purified in the system of a relative closure cleaning, makes system be in high clean state.Pure Silicon Metal in the heating and melting sealed type purification furnace plumbago crucible then.Described heating and melting is for being fused into liquid state by direct current arc discharge heating silicon, and for keeping Pure Silicon Metal liquid impurity elimination effect, the Pure Silicon Metal liquid temp remains on more than 1500 ℃.The positive electrode of described direct current arc discharge is that the graphite of crucible protects holder, and negative potential is the discharge electrode with a certain distance from silicon liquid level, and arc-over directly acts on the liquid-state silicon surface.Described certain distance is set at: 2-50mm.By arc-over silicon is carried out heat fused and keeps the soup shape like this, be beneficial to the material that phosphorus in the silicon liquid etc. has high volatility coefficient and volatilize away, outside vacuum pump discharge system.The internal surface of described plumbago crucible covers and is coated with one deck silicon nitride, and the thickness of coating is 0.5-3mm.The effect of coating is to prevent that liquid-state silicon and plumbago crucible reaction from generating silicon carbide.
Step 2: to the O of the Pure Silicon Metal solution blowing preheated that is molten state
2With the Ar mixed gas.Described preheating O
2With the preheating temperature of Ar mixed gas be more than 1500 ℃.Described step 2 mixed gas O
2Be respectively 0-90% and 10-100% with the concentration of Ar, purity is greater than 99.999%.In this step, crucible bottom is blown into O
2And Ar, liquid towards silicon stirs, and makes phosphorus better rise to the liquid-state silicon surface from liquid inside.Control the stirring dynamics simultaneously, unlikely the seething excessively of liquid silicon contacted with last negative potential, and keep a metastable 2-50mm gap.After phosphorus steam in the liquid-state silicon rises to the liquid-state silicon surface, along with the O that charges into 1500 ℃ of preheatings that does not stop
2With Ar and the outside extraction of vacuum pump, volatile impurity band gone out be sent to environment-friendly disposal system, be discharged in the atmosphere after treatment and go, avoided contaminate environment.
Step 3: stop to be blown into O
2With the Ar mixed gas,, make it upwards carry out directional freeze from the bottom by the bottom quenching of silicon liquid.Described silicon liquid bottom quenching is a removable thermal insulation layer of removing the plumbago crucible bottom, by the heat absorption of the water coolant in the copper pipe, makes the crucible bottom abrupt temperature drop.Described directional freeze is that silicon liquid at first solidifies in the bottom, reduces the power of direct supply simultaneously, and the control surface temperature is upwards carried out directional freeze by the bottom.In this step, determine the volatilization time according to the amount of silicon liquid, general churning time set(ting)value is about 2 hours, is stopping to be blown into O
2Behind the Ar mixed gas, silicon liquid leaves standstill, the impurity come-up that light foamover adheres to, and heavy particle agglomerate impurity sinks, to reach the purpose of separating the weight impurity particle.Because the segregation coefficient of metallic element in silicon liquid is much smaller than 1, therefore directional freeze is one and removes the effectively means of metallic impurity, the plumbago crucible bottom is provided with removable thermal insulation layer in the native system, take out the removable thermal insulation layer in bottom during directional freeze, absorb heat by the water coolant in the copper pipe, make the crucible bottom abrupt temperature drop, because poly-cold the beginning solidifies from the bottom in the bottom, progressively upwards carry out directional freeze then, meanwhile reduce the power of direct supply, the control surface temperature, solid until whole bag silicon water-setting, thereby form a relative directional freeze, can make most of metal impurities assemble two.
Exemplifying embodiment below further specifies:
Example 1: at first the silicon of 600kg is poured in the plumbago crucible, will be vacuumized by vacuum pump 5 in the sealed type purification furnace then, argon gas fills high-purity argon gas through aeration aperture 9, and the repeated multiple times argon filling of finding time remains in the high-purity argon gas environment total system.Open the switch 16 of direct supply 13, heating silicon is fused into and dissolves liquid state, and the temperature of liquid-state silicon 15 is controlled at respectively in the 1500-1550 ℃ of scope.Argon gas and oxygen carry out preheating through heating system, making its temperature is to fill in the liquid-state silicon through aeration aperture 9 more than 1500 ℃, 5 pairs of systems of vacuum pump carry out extracting vacuum simultaneously, and the impurity of easy performance is taken away by vacuum pump 5 along with argon gas and oxygen after be discharged in the atmosphere after environmental protection treatment liquid 3 is handled in the environment friendly system 2.Be blown into O
2After stirring 120 minutes with Ar, stop to be blown into O
2And Ar, and take out movable thermal insulation layer 11, by the crucible bottom heat radiation, the copper pipe 10 absorption silicon liquid bottom temps through the stream water coolant make silicon liquid begin to solidify from the bottom.The power that reduces discharge electrode power supply 13 makes upper temp also along with reduction, form at last from down and on directionally solidified silicon ingots.Take out silicon ingot, remove all around and impurity end to end, after testing, its phosphorus content is 0.47ppm, and the metallic impurity total content is at 3.9ppm, and centre metallic impurity total content is at 0.42ppm.
Embodiment 2: condition is with embodiment 1, and the temperature of liquid-state silicon remains in the 1550-1580 ℃ of scope, charges into preheating argon gas, oxygen and vacuum pump through liquid towards silicon and extracts the mixed gas that contains impurity.Be blown into O
2Behind Ar stirring liquid-state silicon 120min, stop to be blown into O
2And Ar, take out movable thermal insulation layer and begin directionally solidified silicon ingots, remove all around and impurity end to end, after testing, its phosphorus content is 0.24ppm, and the metallic impurity total content is at 3.1ppm, and centre metallic impurity total content is at 0.35ppm.
The foregoing description is not purchased into limitation of the present invention, and all employings are equal to the technical scheme that form obtained of replacement or equivalent transformation, all drop within protection scope of the present invention.
Claims (10)
1. a method of removing the purified silicon of phosphorus and metallic impurity is characterized in that, may further comprise the steps:
Step is poly-1, with the sealed type furnace purge of purifying, the Pure Silicon Metal in the heating and melting sealed type purification furnace plumbago crucible;
Step 2 is to the O of the Pure Silicon Metal solution blowing preheated that is molten state
2With the Ar mixed gas;
Step 3 stops to be blown into O
2With the Ar mixed gas,, make it upwards carry out directional freeze from the bottom by the bottom quenching of silicon liquid;
Step 4, silicon ingot is come out of the stove, and the tail of decaptitating is finished to purify and is obtained high-purity polycrystalline.
2. the method for the purified silicon of removal phosphorus according to claim 1 and metallic impurity, its feature in described step 1 with the sealed type furnace purge of purifying, described purification is to vacuumizing the feeding argon gas in the purification furnace, and then vacuumize the feeding argon gas, repeated multiple times, make to remain in the purification furnace in the high-purity argon gas state, the purity of argon gas is greater than 99.999%.
3. the method for the purified silicon of removal phosphorus according to claim 1 and metallic impurity is characterized in that described step 1 heating and melting for being fused into liquid state by direct current arc discharge heating silicon, and the Pure Silicon Metal liquid temp remains on more than 1500 ℃.
4. the method for the purified silicon of removal phosphorus according to claim 3 and metallic impurity, the positive electrode that it is characterized in that described direct current arc discharge is that the graphite of crucible protects holder, negative potential is the discharge electrode with a certain distance from silicon liquid level, and arc-over directly acts on the liquid-state silicon surface.
5. the method for the purified silicon of removal phosphorus according to claim 4 and metallic impurity is characterized in that described certain distance is set at: 2-50mm.
6. the method for the purified silicon of removal phosphorus according to claim 1 and metallic impurity, the internal surface that it is characterized in that described step 1 plumbago crucible covers and is coated with one deck silicon nitride, and the thickness of coating is 0.5-3mm.
7. the method for the purified silicon of removal phosphorus according to claim 1 and metallic impurity is characterized in that described step 2 preheating O
2With the preheating temperature of Ar mixed gas be more than 1500 ℃.
8. the method for the purified silicon of removal phosphorus according to claim 1 and metallic impurity is characterized in that described step 2 mixed gas O
2Be respectively 0-90% and 10-100% with the concentration of Ar, its purity is greater than 99.999%.
9. the method for the purified silicon of removal phosphorus according to claim 1 and metallic impurity is characterized in that described step 3 silicon liquid bottom quenching is a movable thermal insulation layer of removing the plumbago crucible bottom, by the heat absorption of the water coolant in the copper pipe, makes the crucible bottom abrupt temperature drop.
10. the method for the purified silicon of removal phosphorus according to claim 1 and metallic impurity, it is characterized in that described step 3 directional freeze is that silicon liquid at first solidifies in the bottom, reduce the power of direct supply simultaneously, the control surface temperature is upwards carried out directional freeze by the bottom.
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| CN200910048704A CN101850975A (en) | 2009-04-01 | 2009-04-01 | Method for purifying silicon by removing phosphorus and metal impurities |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102185017A (en) * | 2011-03-16 | 2011-09-14 | 常州市万阳光伏有限公司 | Method for preparing solar-battery-level polycrystalline silicon product |
| CN102336408A (en) * | 2011-03-31 | 2012-02-01 | 宜兴市昱元能源装备技术开发有限公司 | Novel method for purifying silicon |
| CN103072995A (en) * | 2013-02-04 | 2013-05-01 | 福建兴朝阳硅材料股份有限公司 | Method for removing phosphorus in polycrystalline silicon |
| CN105838907A (en) * | 2016-05-23 | 2016-08-10 | 宜兴市昱元能源装备技术开发有限公司 | Titanium purification device and use method |
| CN106987901A (en) * | 2017-03-30 | 2017-07-28 | 江西赛维Ldk太阳能高科技有限公司 | A kind of crystalline silicon and preparation method thereof |
| CN108217657A (en) * | 2016-12-21 | 2018-06-29 | 孙文彬 | Method for purifying high-purity silicon by fractional condensation |
| CN108658080A (en) * | 2018-07-19 | 2018-10-16 | 江苏斯力康科技有限公司 | The method of oxidation processes purifying metal silicon |
| CN110044763A (en) * | 2019-05-06 | 2019-07-23 | 福达合金材料股份有限公司 | Method for detecting content of nitric acid insoluble substances in high-purity silver ingot |
-
2009
- 2009-04-01 CN CN200910048704A patent/CN101850975A/en active Pending
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102185017A (en) * | 2011-03-16 | 2011-09-14 | 常州市万阳光伏有限公司 | Method for preparing solar-battery-level polycrystalline silicon product |
| CN102336408A (en) * | 2011-03-31 | 2012-02-01 | 宜兴市昱元能源装备技术开发有限公司 | Novel method for purifying silicon |
| CN103072995A (en) * | 2013-02-04 | 2013-05-01 | 福建兴朝阳硅材料股份有限公司 | Method for removing phosphorus in polycrystalline silicon |
| CN105838907A (en) * | 2016-05-23 | 2016-08-10 | 宜兴市昱元能源装备技术开发有限公司 | Titanium purification device and use method |
| CN105838907B (en) * | 2016-05-23 | 2017-12-19 | 宜兴市昱元能源装备技术开发有限公司 | Titanium purifying plant and application method |
| CN108217657A (en) * | 2016-12-21 | 2018-06-29 | 孙文彬 | Method for purifying high-purity silicon by fractional condensation |
| CN106987901A (en) * | 2017-03-30 | 2017-07-28 | 江西赛维Ldk太阳能高科技有限公司 | A kind of crystalline silicon and preparation method thereof |
| CN108658080A (en) * | 2018-07-19 | 2018-10-16 | 江苏斯力康科技有限公司 | The method of oxidation processes purifying metal silicon |
| CN110044763A (en) * | 2019-05-06 | 2019-07-23 | 福达合金材料股份有限公司 | Method for detecting content of nitric acid insoluble substances in high-purity silver ingot |
| CN110044763B (en) * | 2019-05-06 | 2022-05-13 | 浙江福达合金材料科技有限公司 | Method for detecting content of nitric acid insoluble substances in high-purity silver ingot |
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Application publication date: 20101006 |