CN104556050A - Method and device for removing metal impurities in polycrystalline silicon by electron beam overheat smelting - Google Patents
Method and device for removing metal impurities in polycrystalline silicon by electron beam overheat smelting Download PDFInfo
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- CN104556050A CN104556050A CN201410829665.3A CN201410829665A CN104556050A CN 104556050 A CN104556050 A CN 104556050A CN 201410829665 A CN201410829665 A CN 201410829665A CN 104556050 A CN104556050 A CN 104556050A
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Abstract
The invention discloses a method and device for removing metal impurities in polycrystalline silicon by electron beam overheat smelting, and belongs to the field of metallurgy. The device comprises a water-cooled copper smelting crucible, wherein an inclined sidewall design is adopted for the water-cooled copper smelting crucible; the inner sidewall of the water-cooled copper smelting crucible forms an included angle of 105 to 120 degrees with the bottom of the water-cooled copper smelting crucible; a graphite bushing is arranged in the water-cooled copper smelting crucible; the outer surface of the graphite bushing is attached to the inner surface of the water-cooled copper smelting crucible to form a close fit design; the bottom of the graphite bushing and the bottom of the water-cooled copper smelting crucible are horizontal, the inner surface sidewall of the graphite bushing forms an included angle of 95 to 100 degrees with the bottom of the graphite bushing. According to the device, the metal impurities are removed by overheat smelting, so that the number of times of subsequent directional solidification and ingot casting can be reduced, a purification process can be eliminated, and the production cost can be reduced; by electron beam overheat smelting for polycrystalline silicon purification, post directional solidification can be reduced by one time or more, and the metal impurities in the polycrystalline silicon can be reduced by 30 percent or more.
Description
Technical field
The present invention relates to a kind of electron beam and cross the method that hot smelting removes metallic impurity in polysilicon, belong to field of metallurgy.
Background technology
Metallurgy method prepares solar-grade polysilicon, due to features such as its cost is low, energy consumption is little, environmental friendliness, is promoted widely and adopts at present.In the technique of purifying, according to the existence form of impurity in polysilicon and the physicochemical property of each impurity element, mainly utilize the boron impurity in the method for slag making melting removal polysilicon, utilize the method for directional freeze (ingot casting) or pickling to remove the metallic impurity in polysilicon, the phosphorus impurities utilized in the method removal polysilicon of electron beam melting or vacuum melting.
At present, for the polysilicon of metallic impurity total concn more than 1000ppmw, need metallic impurity total concn to be reduced to below 1ppmw through the twice even directional solidification technique of more than twice.And directional solidification technique proposes the process time once greatly about 1 ~ 2 day time, the production time is longer, and wastes a large amount of electric power in the process of repeatedly purifying.
Summary of the invention
In order to solve the problem, the invention provides the overheated smelting technique of a kind of electron beam, make polysilicon just can carry out a directional freeze when electron beam melting, lower difficulty and the cost of subsequent disposal.
The object of this invention is to provide a kind of device of electron beam melting polysilicon, comprise water-cooled smelting pot, described water jacketed copper crucible adopts tilting sidewall design, at the bottom of described water jacketed copper crucible inner side-wall and water jacketed copper crucible, angle is 105 ~ 120 °, graphite bushing is provided with in described water jacketed copper crucible, described graphite bushing outside surface and water jacketed copper crucible internal surface are fitted, wringing fit designs, the bottom of graphite bushing and water jacketed copper crucible bottom level, at the bottom of described graphite bushing internal surface sidewall and graphite bushing, angle is 95 ~ 100 °.
Further, in technique scheme, described graphite bushing bottom thickness is 20 ~ 40mm, and bottom the side thickness of described graphite substrate, degree is more than or equal to 20mm.
Further, in technique scheme, the ratio between the internal height of described graphite bushing and bottom width is 1:1 ~ 2:1.
Another object of the present invention is to provide a kind of electron beam and crosses the method that hot smelting removes metallic impurity in polysilicon, it is characterized in that comprising the following steps:
A. water jacketed copper crucible is placed in the below of electron beam gun, graphite bushing is placed in water jacketed copper crucible, the silicon material being broken into 10 ~ 30mm is loaded in graphite bushing, described silicon material is filled the feeding device of electron beam melting simultaneously;
B. pre-thermionic electron guns;
C. fusing, melting silicon material; The simultaneously high pressure of unlocking electronic rifle and line, promote monitor system to the 200 ~ 300kW of electron beam gun gradually, power ascension speed is 5 ~ 10kW/min; After melted silicon material, continue melting 20-40min; Thermal conductivity due to graphite material is far smaller than the thermal conductivity of copper material, so graphite bushing has insulation effect, the silicon melt under electron beam melting can be made to reach the superheat state of 2000 ~ 2600 DEG C, and the removal speed of the volatile impunty on silicon melt surface is accelerated.Simultaneously, because the not uniform thickness of graphite bushing sidewall designs, make the temperature of silicon melt present the thermograde raised gradually from bottom to top, form directional freeze trend, make metallic impurity gradually to silicon melt surface transport or motion, the volatile impunty reaching silicon melt surface is removed;
D. close electron beam gun, the silicon material furnace cooling 1 ~ 3h after melting, closes diffusion pump, lobe pump, mechanical pump successively, opens purging valve, and opening device door takes out silicon ingot;
E. the impurity of non-volatility can concentrate on the upper surface of silicon ingot due to directional freeze effect, upper surface excision 5 ~ 10mm.
Further, in upper art technical scheme, in step b, closing device door, opens mechanical pump, lobe pump, diffusion pump successively, makes the vacuum tightness of working chamber reach 5 × 10
-2pa, the vacuum tightness of electron beam gun reaches 5 × 10
-3pa; It is 25-35kW that electron beam gun arranges high pressure, and after high pressure preheating 5-10min, close high pressure, arranging electron beam gun line is 70-200mA, line preheating 5-10min, closes electron beam gun line.
Further, in technique scheme, in step c, along with the carrying out of melting, in graphite bushing, add silicon material by feeding device, repeating step c, until reach specified amount.
The present invention by adding graphite bushing in water jacketed copper crucible in electron-beam melting system, hot smelting was carried out to silicon melt, silicon melt is dispelled the heat not in time, under the effect of thermograde, silicon melt inside forms directional freeze trend from bottom to top, and metallic impurity are enriched to top, and volatile impunty is overflowed from silicon melt top, non-volatile impurities finally freezes solidly on the top of silicon ingot, finally cut.
Invention beneficial effect
In apparatus of the present invention, carry out hot smelting removed metallic impurity, the number of times of follow-up directional freeze and ingot casting can be reduced, reduced purifying technique, reduce production cost; Polycrystalline silicon purifying electron beam crosses hot smelting can reduce later stage directional freeze number of times more than 1 time; Polycrystalline silicon purifying electron beam crosses hot smelting can reduce metallic impurity more than 30% in polysilicon.
Accompanying drawing explanation
Accompanying drawing 1 width of the present invention,
Fig. 1 is apparatus of the present invention structural representations;
In figure, 1, water jacketed copper crucible; 2, graphite muff.
Embodiment
Following nonlimiting examples can make the present invention of those of ordinary skill in the art's comprehend, but does not limit the present invention in any way.
Test method described in following embodiment, if no special instructions, is ordinary method; Described reagent and material, if no special instructions, all can obtain from commercial channels.
Embodiment 1
As shown in Figure 1, a kind of device of electron beam melting polysilicon, comprise water-cooled smelting pot, at the bottom of described water jacketed copper crucible inner side-wall and water jacketed copper crucible, angle is 105 °, graphite bushing is provided with in described water jacketed copper crucible, described graphite bushing outside surface and water jacketed copper crucible internal surface are fitted, the bottom of graphite bushing and water jacketed copper crucible bottom level, and at the bottom of described graphite bushing internal surface sidewall and graphite bushing, angle is 95 °.
Described graphite bushing bottom thickness is 20mm.
The sidewall thinnest part thickness of described graphite substrate equals 20mm.
Ratio between the internal height H of described graphite bushing and bottom width W is 1:1.
Electron beam crosses the method that hot smelting removes metallic impurity in polysilicon, comprises the following steps:
A. water jacketed copper crucible is placed in the below of electron beam gun, graphite bushing is placed in water jacketed copper crucible, the silicon material being broken into 10 ~ 30mm is loaded in graphite bushing, described silicon material is filled the feeding device of electron beam melting simultaneously;
B. pre-thermionic electron guns; Closing device door, opens mechanical pump, lobe pump, diffusion pump successively, makes the vacuum tightness of working chamber reach 5 × 10
-2pa, the vacuum tightness of electron beam gun reaches 5 × 10
-3pa; It is 25kW that electron beam gun arranges high pressure, and after high pressure preheating 10min, close high pressure, arranging electron beam gun line is 70mA, line preheating 10min, closes electron beam gun line;
C. fusing, melting silicon material; The simultaneously high pressure of unlocking electronic rifle and line, promote the monitor system of electron beam gun gradually to 200kW, power ascension speed is 5kW/min; After melted silicon material, continue melting 40min; Thermal conductivity due to graphite material is far smaller than the thermal conductivity of copper material, so graphite bushing has insulation effect, the silicon melt under electron beam melting can be made to reach the superheat state of 2000 DEG C, and the removal speed of the volatile impunty on silicon melt surface is accelerated.Simultaneously, because the not uniform thickness of graphite bushing sidewall designs, make the temperature of silicon melt present the thermograde raised gradually from bottom to top, form directional freeze trend, make metallic impurity gradually to silicon melt surface transport or motion, the volatile impunty reaching silicon melt surface is removed;
D. along with the carrying out of melting, in graphite bushing, silicon material is added by feeding device, repeating step c, until reach specified amount;
E. close electron beam gun, the silicon material furnace cooling 1h after melting, closes diffusion pump, lobe pump, mechanical pump successively, opens purging valve, and opening device door takes out silicon ingot;
F. the impurity of non-volatility can concentrate on the upper surface of silicon ingot due to directional freeze effect, upper surface excision 10mm.
Embodiment 2
As shown in Figure 1, a kind of device of electron beam melting polysilicon, comprise water-cooled smelting pot, at the bottom of described water jacketed copper crucible inner side-wall and water jacketed copper crucible, angle is 110 °, graphite bushing is provided with in described water jacketed copper crucible, described graphite bushing outside surface and water jacketed copper crucible internal surface are fitted, the bottom of graphite bushing and water jacketed copper crucible bottom level, and at the bottom of described graphite bushing internal surface sidewall and graphite bushing, angle is 97 °.
Described graphite bushing bottom thickness is 30mm.
The sidewall thinnest part thickness of described graphite substrate equals 20mm.
Ratio between the internal height H of described graphite bushing and bottom width W is 1.5:1.
Electron beam crosses the method that hot smelting removes metallic impurity in polysilicon, comprises the following steps:
A. water jacketed copper crucible is placed in the below of electron beam gun, graphite bushing is placed in water jacketed copper crucible, the silicon material being broken into 10 ~ 30mm is loaded in graphite bushing, described silicon material is filled the feeding device of electron beam melting simultaneously;
B. pre-thermionic electron guns; Closing device door, opens mechanical pump, lobe pump, diffusion pump successively, makes the vacuum tightness of working chamber reach 5 × 10
-2pa, the vacuum tightness of electron beam gun reaches 5 × 10
-3pa; It is 30kW that electron beam gun arranges high pressure, and after high pressure preheating 8min, close high pressure, arranging electron beam gun line is 135mA, line preheating 8min, closes electron beam gun line;
C. fusing, melting silicon material; The simultaneously high pressure of unlocking electronic rifle and line, promote the monitor system of electron beam gun gradually to 250kW, power ascension speed is 7.5kW/min; After melted silicon material, continue melting 20min; Thermal conductivity due to graphite material is far smaller than the thermal conductivity of copper material, so graphite bushing has insulation effect, the silicon melt under electron beam melting can be made to reach the superheat state of 2300 DEG C, and the removal speed of the volatile impunty on silicon melt surface is accelerated.Simultaneously, because the not uniform thickness of graphite bushing sidewall designs, make the temperature of silicon melt present the thermograde raised gradually from bottom to top, form directional freeze trend, make metallic impurity gradually to silicon melt surface transport or motion, the volatile impunty reaching silicon melt surface is removed;
D. along with the carrying out of melting, in graphite bushing, silicon material is added by feeding device, repeating step c, until reach specified amount;
E. close electron beam gun, the silicon material furnace cooling 2h after melting, closes diffusion pump, lobe pump, mechanical pump successively, opens purging valve, and opening device door takes out silicon ingot;
F. the impurity of non-volatility can concentrate on the upper surface of silicon ingot due to directional freeze effect, upper surface excision 8mm.
Embodiment 3
As shown in Figure 1, a kind of device of electron beam melting polysilicon, comprise water-cooled smelting pot, at the bottom of described water jacketed copper crucible inner side-wall and water jacketed copper crucible, angle is 120 °, graphite bushing is provided with in described water jacketed copper crucible, described graphite bushing outside surface and water jacketed copper crucible internal surface are fitted, the bottom of graphite bushing and water jacketed copper crucible bottom level, and at the bottom of described graphite bushing internal surface sidewall and graphite bushing, angle is 100 °.
Described graphite bushing bottom thickness is 40mm.
The sidewall thinnest part thickness of described graphite substrate equals 20mm.
Ratio between the internal height H of described graphite bushing and bottom width W is 2:1.
Electron beam crosses the method that hot smelting removes metallic impurity in polysilicon, comprises the following steps:
A. water jacketed copper crucible is placed in the below of electron beam gun, graphite bushing is placed in water jacketed copper crucible, the silicon material being broken into 10 ~ 30mm is loaded in graphite bushing, described silicon material is filled the feeding device of electron beam melting simultaneously;
B. pre-thermionic electron guns; Closing device door, opens mechanical pump, lobe pump, diffusion pump successively, makes the vacuum tightness of working chamber reach 5 × 10
-2pa, the vacuum tightness of electron beam gun reaches 5 × 10
-3pa; It is 35kW that electron beam gun arranges high pressure, and after high pressure preheating 5min, close high pressure, arranging electron beam gun line is 200mA, line preheating 5min, closes electron beam gun line;
C. fusing, melting silicon material; The simultaneously high pressure of unlocking electronic rifle and line, promote the monitor system of electron beam gun gradually to 300kW, power ascension speed is 10kW/min; After melted silicon material, continue melting 20-40min; Thermal conductivity due to graphite material is far smaller than the thermal conductivity of copper material, so graphite bushing has insulation effect, the silicon melt under electron beam melting can be made to reach the superheat state of 2600 DEG C, and the removal speed of the volatile impunty on silicon melt surface is accelerated.Simultaneously, because the not uniform thickness of graphite bushing sidewall designs, make the temperature of silicon melt present the thermograde raised gradually from bottom to top, form directional freeze trend, make metallic impurity gradually to silicon melt surface transport or motion, the volatile impunty reaching silicon melt surface is removed;
D. along with the carrying out of melting, in graphite bushing, silicon material is added by feeding device, repeating step c, until reach specified amount;
E. close electron beam gun, the silicon material furnace cooling 3h after melting, closes diffusion pump, lobe pump, mechanical pump successively, opens purging valve, and opening device door takes out silicon ingot;
F. the impurity of non-volatility can concentrate on the upper surface of silicon ingot due to directional freeze effect, upper surface excision 5mm.
Claims (6)
1. an electron beam crosses the device that hot smelting removes metallic impurity in polysilicon, comprise water-cooled smelting pot, it is characterized in that: at the bottom of described water jacketed copper crucible inner side-wall and water jacketed copper crucible, angle is 105 ~ 120 °, graphite bushing is provided with in described water jacketed copper crucible, described graphite bushing outside surface and water jacketed copper crucible internal surface are fitted, the bottom of graphite bushing and water jacketed copper crucible bottom level, at the bottom of described graphite bushing internal surface sidewall and graphite bushing, angle is 95 ~ 100 °.
2. device according to claim 1, is characterized in that: described graphite bushing bottom thickness is 20 ~ 40mm; The sidewall bottom thickness of described graphite substrate is more than or equal to 20mm.
3. device according to claim 1 and 2, is characterized in that: the ratio between the internal height of described graphite bushing and bottom width is 1:1 ~ 2:1.
4. utilize device described in claim 1 ~ 3 to carry out electron beam and cross the method that hot smelting removes metallic impurity in polysilicon, it is characterized in that comprising the following steps:
A. water jacketed copper crucible is placed in the below of electron beam gun, graphite bushing is placed in water jacketed copper crucible, the silicon material being broken into 10 ~ 30mm is loaded in graphite bushing, described silicon material is filled the feeding device of electron beam melting simultaneously;
B. pre-thermionic electron guns;
C. fusing, melting silicon material; The simultaneously high pressure of unlocking electronic rifle and line, promote monitor system to the 200 ~ 300kW of electron beam gun gradually, power ascension speed is 5 ~ 10kW/min, after melted silicon material, continues melting 20-40min;
D. close electron beam gun, the silicon material furnace cooling 1 ~ 3h after melting, closes diffusion pump, lobe pump, mechanical pump successively, opens purging valve, and opening device door takes out silicon ingot;
E. the impurity of non-volatility can concentrate on the upper surface of silicon ingot due to directional freeze effect, excision silicon ingot upper surface 5 ~ 10mm.
5. method according to claim 4, is characterized in that: in step b that closing device door opens mechanical pump, lobe pump, diffusion pump successively, makes the vacuum tightness of working chamber reach 5 × 10
-2pa, the vacuum tightness of electron beam gun reaches 5 × 10
-3pa; It is 25-35kW that electron beam gun arranges high pressure, and after high pressure preheating 5-10min, close high pressure, arranging electron beam gun line is 70-200mA, line preheating 5-10min, closes electron beam gun line.
6. method according to claim 4, is characterized in that: in step c, adds silicon material after melting by feeding device in graphite bushing, repeating step c, until reach specified amount.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107128928A (en) * | 2017-05-25 | 2017-09-05 | 宁夏东梦能源股份有限公司 | Utilize the method for electron beam furnace purifying polycrystalline silicon |
| CN108101064A (en) * | 2017-12-23 | 2018-06-01 | 青岛蓝光晶科新材料有限公司 | A kind of method of hard inclusions in temperature gradient divided silicon |
| CN112095019A (en) * | 2020-08-11 | 2020-12-18 | 大连理工大学 | Method for removing inclusions in high-temperature alloy through electron beam overheating dissolution |
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| JP2001294416A (en) * | 2000-04-07 | 2001-10-23 | Mitsubishi Materials Polycrystalline Silicon Corp | Device for producing polycrystalline silicon |
| CN202267357U (en) * | 2011-08-03 | 2012-06-06 | 宁夏宁电光伏材料有限公司 | Water cooling device of graphite and coating substrate for electron beam melting |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107128928A (en) * | 2017-05-25 | 2017-09-05 | 宁夏东梦能源股份有限公司 | Utilize the method for electron beam furnace purifying polycrystalline silicon |
| CN108101064A (en) * | 2017-12-23 | 2018-06-01 | 青岛蓝光晶科新材料有限公司 | A kind of method of hard inclusions in temperature gradient divided silicon |
| CN108101064B (en) * | 2017-12-23 | 2021-02-09 | 青岛蓝光晶科新材料有限公司 | Method for separating hard impurities in silicon by temperature gradient |
| CN112095019A (en) * | 2020-08-11 | 2020-12-18 | 大连理工大学 | Method for removing inclusions in high-temperature alloy through electron beam overheating dissolution |
| CN112095019B (en) * | 2020-08-11 | 2021-07-30 | 大连理工大学 | Method for removing inclusions in high-temperature alloy through electron beam overheating dissolution |
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