CN203699922U - Device for efficiently removing impurity oxygen in polycrystalline silicon by electron beam melting - Google Patents

Device for efficiently removing impurity oxygen in polycrystalline silicon by electron beam melting Download PDF

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Publication number
CN203699922U
CN203699922U CN201320745900.XU CN201320745900U CN203699922U CN 203699922 U CN203699922 U CN 203699922U CN 201320745900 U CN201320745900 U CN 201320745900U CN 203699922 U CN203699922 U CN 203699922U
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electron
melting
silicon
oxygen
polycrystalline silicon
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Expired - Fee Related
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CN201320745900.XU
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Chinese (zh)
Inventor
王登科
郭校亮
姜大川
安广野
谭毅
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Qingdao Changsheng Electric Design Institute Co. Ltd.
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Qingdao Longsheng Crystal Silicon Technology Co Ltd
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Abstract

The utility model belongs to the field of purification of polycrystalline silicon, and particularly relates to a device for efficiently removing impurity oxygen in polycrystalline silicon by electron beam melting. A traditional electron beam melting mode is broken, the electron beam melting is not performed in a melting crucible, while electron beam deoxidization melting is performed by use of a flow guide groove, since silicon fluid can disperse in a flow guide area, the specific surface area is increased, so that the electron beam melting deoxidization effect is better. The device provided by the utility model has the advantages that (1) the process method and use of electron beam deoxidization are provided to solve the problem that impurity oxygen in polycrystalline silicon is difficult to remove, the oxygen content can be reduced to be lower than 0.0571 ppmw to meet the requirements of a solar cell on the oxygen content of a polycrystalline silicon cast ingot; (2) the efficient zonal deoxidization technology of polycrystalline silicon materials can be used for increasing the superficial area of silicon liquid by more than 30%, and the deoxidization time is shortened by more than 20%; (3) continuous production can be achieved and the production efficiency is improved by more than 35%.

Description

The device of impurity oxygen in polysilicon is efficiently removed in electron beam melting
Technical field
The utility model belongs to polycrystalline silicon purifying field, is specifically related to a kind of electron beam melting and efficiently removes the device of impurity oxygen in polysilicon.
Background technology
At present, China has become world energy sources production and consumption big country, but energy expenditure level is also very low per capita.Along with economical and social development, China's energy demand is by sustainable growth, for current energy shortage situation, deep thinking is all being carried out in countries in the world, and effort improves efficiency of energy utilization, promote the development and application of renewable energy source, reduce the dependence to Imported oil, strengthen energy security.
Solar energy power generating development in recent years as one of important development direction of renewable energy source is swift and violent, and its proportion is increasing.According to " planning of renewable energy source Long-and Medium-term Development ", to the year two thousand twenty, China strives making solar electrical energy generation installed capacity to reach 1.8GW(gigawatt), will reach 600GW to the year two thousand fifty.Expect the year two thousand fifty, the electric power installation of Chinese renewable energy source will account for 25% of national electric power installation, and wherein photovoltaic generation installation will account for 5%.Before estimating the year two thousand thirty, the compound growth rate of Chinese sun power installed capacity will be up to more than 25%.
The development of photovoltaic industry depends on the purification to polycrystalline silicon raw material.The purifying technique of polycrystalline silicon raw material is several technique below main dependence at present: Siemens Method, silane thermal decomposition process, gas fluidized bed method and metallurgy method.Metallurgy method is prepared solar-grade polysilicon technology the only way which must be passed as development low cost, eco-friendly solar-grade polysilicon technology of preparing, has obtained at present tremendous development, and has realized suitability for industrialized production.Metallurgy method purifying polycrystalline silicon refers to the physical metallurgy means that adopt, in the situation that silicon does not participate in chemical reaction occurs, remove successively the method for the various impurity elements (phosphorus, boron and metal) in silicon, it is not single preparation method, but a kind of Integration Method mainly utilizes saturated vapor pressure principle, segregation principle and oxidisability difference principle, adopts respectively different processing methodes, the impurity element of making a return journey in silica removal, thus be met the silicon material of solar energy polycrystalline silicon purity requirement.
In metallurgy method technique, the phosphorus of silicon material, boron, metal impurities all can be removed by effective process means, have reached comparatively ideal effect.But, in to the research of polysilicon solar battery slice electricity conversion, find in recent years, the content of oxygen element produces material impact to the electricity conversion of cell piece, and general oxygen is in the time of interstitial site, conventionally aobvious electroactive, however in casting polycrystalline silicon oxygen concn conventionally 3 × 10 17~1.4 × 10 18cm -3between, the interstitial oxygen concentration of high density, in device fabrication process subsequently, experiences the thermal treatment of all temps, and meeting segregation and precipitation in silicon crystal form oxygen and close the defects such as alms giver, oxygen precipitation.Simultaneously, in silicon crystal material growth, cooling process because the solubility with temperature of oxygen reduces and declines rapidly, oversaturated oxygen will form primary oxygen precipitation in casting polycrystalline silicon, also may form various complex bodys with other impurity, as N-O, C-O complex body.These oxygen precipitations and complex body thereof not only can reduce the effect of the outer gettering of phosphorus, even directly become the short-channel of battery.
These oxygen defects have the impact of favourable and unfavorable two aspects on silicon materials and device, it can form intrinsic gettering in conjunction with device technology, absorb metallic impurity, all right pinning dislocation, the physical strength of raising silicon chip, but in the time that oxygen precipitation is excessive, can induce again other lattice defect, introduce a large amount of secondary defects, also can attract the metallic elements such as iron, form iron oxygen precipitation complex body, there is very strong few sub-compound ability, can significantly reduce the conversion efficiency of solar cell of material.
In the technique such as directional freeze, ingot casting of metallurgy method, the oxygen element in crucible or the oxygen element passing in gas inevitably can enter into silicon material, are the major causes that oxygen impurities produces.In traditional test silicon, the common method of oxygen level is infrared spectra, respectively HIGH-PURITY SILICON material and batch mixing (scrap stock after casting casting mix with high-purity material) are detected with infrared spectra, in two kinds of material, the content of oxygen is more or less the same, and this has also caused the oxygen impurities of introducing in metallurgy method technique not come into one's own.
In fact, in silicon, oxygen element has two states: substitute position, oxo has been replaced the position of silicon; Gap digit, oxygen is in the gap of Siliciumatom.The oxygen level that in traditional test silicon, the infrared spectra of oxygen level can only detector gap position, can not truly reflect two kinds of oxygen levels in silicon material.Through applicant's experiment test, the oxygen that substitutes position can discharge electronics, similar to the effect that foreign matter of phosphor in silicon produces, and can affect polycrystalline silicon battery plate electricity conversion.Applicant is by sims repeated detection, and in above-mentioned two kinds of silicon material, oxygen element content differs greatly, and is mainly the difference that substitutes the oxygen element content of position.Therefore, can not ignore for the impurity oxygen of introducing in the techniques such as ingot casting, must seek the content of impurity oxygen in effective means reduction silicon.
But, in prior art, not good to the removal effect of oxygen element.For the removal method of oxygen impurities, retrieve the method that mono-kind of utility model patent CN200810070925 reduces oxygen in Pure Silicon Metal, carbon content, this utility model adopts and in silicon liquid, is blown into oxygen, hydrogen and water vapour, hydrogen and oxygen are reacted in silicon liquid and produce localized hyperthermia, oxygen, carbon in silicon liquid are removed with gaseous emission, but the method need to pass into oxygen and hydrogen under silicon molten state, operation easier is large, dangerous high, the removal effect of oxygen is not good.
Utility model content
According to above the deficiencies in the prior art, the utility model proposes a kind of electron beam melting and efficiently remove the device of impurity oxygen in polysilicon, effectively remove impurity oxygen in polysilicon by the mode of electron beam melting, improve the photoelectric transformation efficiency of cell piece with this.
The device of impurity oxygen in polysilicon is efficiently removed in electron beam melting described in the utility model, comprise body of heater, body of heater internal upper part is provided with the diversion trench of water-cooled, this diversion trench from up to down tilts, sidewall of the furnace body leads to feed mechanism, and the discharge port of this feed mechanism is positioned at diversion trench and is positioned at one end top of eminence; Lead at the body of heater top that is positioned at diversion trench top fusing electron beam gun and melting electron beam gun; Mouthful body of heater inner bottom part for below that comes down in torrents of diversion trench is provided with solidification crucible.
Solidification crucible is preferably the copper crucible with water-cooled.For solidification crucible itself, both can adopt plumbago crucible, also can adopt quartz crucible, but in the time that silicon liquid is cast downwards, easily broken, and easily bring other contaminating impurity, utilize the copper crucible with water-cooled, its cooling power is stronger, cooling time is shorter, pollution-free, simultaneously can Reusability, holistic cost is lower, and not fragile.
Angle of inclination between diversion trench and horizontal plane is 5~15 degree.Less angle of inclination can ensure that silicon liquid obtains abundant melting in diversion trench, ensures the effect of deoxygenation.
Adopt said apparatus to carry out electron beam melting and efficiently remove impurity oxygen in polysilicon, electron beam melting furnace is vacuumized, then in the diversion trench with water-cooled, continue to send silicon material by feed mechanism, silicon material is melted with electron beam gun by fusing, the silicon liquid of fusing moves downward the solidification crucible flowing in electron beam melting furnace along diversion trench, in water conservancy diversion region, carry out electron beam melting by melting with electron beam gun, after solidification crucible reaches bearing capacity, stop feed mechanism feeding, close fusing electron beam gun and melting electron beam gun, after cooling, silicon ingot in solidification crucible is taken out.
Preferably carry out according to following steps:
(1) get the raw materials ready: using through electron beam melting purify after silicon material put into solidification crucible inner bottom part as solidifying bed material; The silicon material for the treatment of electron beam melting is put into feed mechanism;
(2) pre-treatment: open cooling water circulation to electron beam melting furnace and diversion trench, to vacuumizing processing in electron beam melting furnace, be evacuated to below 0.05Pa, and fusing is vacuumized to processing with electron beam gun and melting electron beam gun, be evacuated to below 0.005Pa, then carry out preheating, it is 70~200mA that electron beam line is set, after pre-thermionic electron guns 10~15min, close preheating;
(3) melting is purified: start feed mechanism, continue to add silicon material in the diversion trench with water-cooled, start fusing electron beam gun, setting electron beam line is 200~1200mA, controlled melting distributes by the beam energy of electron beam gun, the silicon material adding is fused into silicon liquid, now start melting electron beam gun, setting electron beam line is 200~800mA, the beam energy of controlling melting electron beam gun distributes, the silicon liquid flowing downward is carried out to melting deoxygenation, finally by flowing into after water conservancy diversion in solidification crucible, after solidification crucible reaches bearing capacity, stop feed mechanism feeding, close fusing electron beam gun and melting electron beam gun, through cooling to below 200 DEG C, close vacuum system, take out the silicon ingot in solidification crucible to blow-on after inflation in electron beam melting furnace.
Wherein, the silicon material oxygen level for the treatment of electron beam melting is preferably 4~20ppmw.
In the utility model, break traditional electron beam melting pattern, in smelting pot, do not carry out electron beam melting, carry out electron beam deoxygenation melting but use diversion trench, because silicon liquid can spread loose in water conservancy diversion region, specific surface area increases, therefore electron beam melting better effects if, because water conservancy diversion region is downward-sloping structure, silicon liquid after melting is purified flows in solidification crucible, in solidification crucible, pile up, generally select the solidification crucible of large-size, facilitate once electron beam melting technology to reach larger single furnace output.
The utility model has the advantage of: (1) has proposed processing method and the purposes of electron beam deoxygenation, solve the difficult problem that in polysilicon, impurity oxygen is removed, polysilicon after deoxygenation detects through second ion mass spectroscopy (SIMS), its oxygen level is lower than second ion mass spectroscopy limit of detection, lower than 0.0571ppmw, meet the requirement of solar cell to polycrystalline silicon ingot casting oxygen level; (2) the efficient banded deoxygenation technology of polycrystalline silicon material can increase silicon liquid surface-area more than 30%, shortens the deoxygenation time more than 20%; (3) can realize serialization and produce, enhance productivity more than 35%.
Brief description of the drawings
Fig. 1 is structural representation of the present utility model;
In figure: 1, body of heater 2, diversion trench 3, fusing electron beam gun 4, electron beam gun 5, feed mechanism 6, solidification crucible for melting.
Embodiment
Below in conjunction with accompanying drawing, the utility model being described further.
Embodiment 1:
As shown in Figure 1, the device of impurity oxygen in polysilicon is efficiently removed in a kind of electron beam melting, comprise body of heater 1, body of heater 1 internal upper part is provided with the diversion trench 2 of water-cooled, this diversion trench 2 from up to down tilts, body of heater 1 sidewall leads to feed mechanism 5, and the discharge port of this feed mechanism 5 is positioned at diversion trench 2 and is positioned at one end top of eminence; Lead at body of heater 1 top that is positioned at diversion trench 2 tops has fusing electron beam gun 3 and electron beam gun 4 for melting; Mouthful body of heater 1 inner bottom part for below that comes down in torrents of diversion trench 2 is provided with solidification crucible 6.
Solidification crucible 6 is the copper crucible with water-cooled.For solidification crucible 6, both can adopt plumbago crucible, also can adopt quartz crucible, but in the time that silicon liquid is cast downwards, easily broken, and easily bring other contaminating impurity, utilize the copper crucible with water-cooled, its cooling power is stronger, cooling time is shorter, pollution-free, simultaneously can Reusability, holistic cost is lower, and not fragile.
Angle of inclination between diversion trench 2 and horizontal plane is 15 degree.Less angle of inclination can ensure that silicon liquid obtains abundant melting in diversion trench 2, ensures the effect of deoxygenation.
Embodiment 2:
The device that adopts embodiment 1, carries out electron beam melting and efficiently removes impurity oxygen in polysilicon.
(1) get the raw materials ready: be to put into feed mechanism 5 after 10~12mm, the oxygen level polycrystalline silicon material cleaning, drying that is 20ppmw by granular size; Using through electron beam melting purify after silicon material put into solidification crucible 6 inner bottom parts as solidifying bed material;
(2) pre-treatment: open cooling water circulation to electron beam melting furnace and diversion trench 2, to vacuumizing processing in electron beam melting furnace, be evacuated to below 0.05Pa, and fusing is vacuumized to processing with electron beam gun 3 and melting electron beam gun 4, be evacuated to below 0.005Pa, then carry out preheating, it is 150mA that electron beam line is set, after preheating 15min, close preheating;
(3) melting is purified: start feed mechanism 5, continue to add silicon material in the diversion trench 2 with water-cooled, start fusing electron beam gun 3, setting electron beam line is 400mA, controlled melting distributes by the beam energy of electron beam gun 3, the silicon material adding is fused into silicon liquid, now start electron beam gun 4 for melting, setting electron beam line is 400mA, the beam energy of controlling melting electron beam gun 4 distributes, the silicon liquid flowing downward is carried out to melting deoxygenation, finally by flowing into after water conservancy diversion in solidification crucible 6, after solidification crucible 6 reaches bearing capacity, stop feed mechanism 5 feedings, close fusing electron beam gun 3 and electron beam gun 4 for melting, through cooling to below 200 DEG C, close vacuum system, take out the silicon ingot in solidification crucible 6 to blow-on after inflation in electron beam melting furnace.Polysilicon after deoxygenation detects through second ion mass spectroscopy (SIMS), and its oxygen level is lower than second ion mass spectroscopy limit of detection, lower than 0.0571ppmw.
Embodiment 3:
The device that adopts embodiment 1, carries out electron beam melting and efficiently removes impurity oxygen in polysilicon.
(1) get the raw materials ready: be to put into feed mechanism 5 after 10~12mm, the oxygen level polycrystalline silicon material cleaning, drying that is 10ppmw by granular size; Using through electron beam melting purify after silicon material put into solidification crucible 6 inner bottom parts as solidifying bed material;
(2) pre-treatment: open cooling water circulation to electron beam melting furnace and diversion trench 2, to vacuumizing processing in electron beam melting furnace, be evacuated to below 0.05Pa, and fusing is vacuumized to processing with electron beam gun 3 and melting electron beam gun 4, be evacuated to below 0.005Pa, then carry out preheating, it is 200mA that electron beam line is set, after pre-thermionic electron guns 10min, close preheating;
(3) melting is purified: start feed mechanism 5, continue to add silicon material in the diversion trench 2 with water-cooled, start fusing electron beam gun 3, setting electron beam line is 800mA, controlled melting distributes by the beam energy of electron beam gun 3, the silicon material adding is fused into silicon liquid, now start electron beam gun 4 for melting, setting electron beam line is 800mA, the beam energy of controlling melting electron beam gun 4 distributes, the silicon liquid flowing downward is carried out to melting deoxygenation, finally by flowing into after water conservancy diversion in solidification crucible 6, after solidification crucible 6 reaches bearing capacity, stop feed mechanism 5 feedings, close fusing electron beam gun 3 and electron beam gun 4 for melting, through cooling to below 200 DEG C, close vacuum system, take out the silicon ingot in solidification crucible 6 to blow-on after inflation in electron beam melting furnace.Polysilicon after deoxygenation detects through second ion mass spectroscopy (SIMS), and its oxygen level is lower than second ion mass spectroscopy limit of detection, lower than 0.0571ppmw.

Claims (3)

1. the device of impurity oxygen in polysilicon is efficiently removed in an electron beam melting, comprise body of heater, it is characterized in that body of heater internal upper part is provided with the diversion trench of water-cooled, this diversion trench from up to down tilts, sidewall of the furnace body leads to feed mechanism, and the discharge port of this feed mechanism is positioned at diversion trench and is positioned at one end top of eminence; Lead at the body of heater top that is positioned at diversion trench top fusing electron beam gun and melting electron beam gun; Mouthful body of heater inner bottom part for below that comes down in torrents of diversion trench is provided with solidification crucible.
2. the device of impurity oxygen in polysilicon is efficiently removed in electron beam melting according to claim 1, it is characterized in that solidification crucible is the copper crucible with water-cooled.
3. the device of impurity oxygen in polysilicon is efficiently removed in electron beam melting according to claim 1, it is characterized in that the angle of inclination between diversion trench and horizontal plane is 5~15 degree.
CN201320745900.XU 2013-11-22 2013-11-22 Device for efficiently removing impurity oxygen in polycrystalline silicon by electron beam melting Expired - Fee Related CN203699922U (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104649276A (en) * 2013-11-22 2015-05-27 青岛隆盛晶硅科技有限公司 Method and device for efficient removal of impurity oxygen from polysilicon by electron beam melting

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104649276A (en) * 2013-11-22 2015-05-27 青岛隆盛晶硅科技有限公司 Method and device for efficient removal of impurity oxygen from polysilicon by electron beam melting
CN104649276B (en) * 2013-11-22 2018-09-25 青岛昌盛日电太阳能科技股份有限公司 Electron-beam smelting efficiently removes the method and its device of impurity oxygen in polysilicon

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Effective date of registration: 20171103

Address after: 1 road 266000 in Shandong province Qingdao city Laoshan District No. 1 Keyuan latitude B block 7 layer B4-2

Patentee after: Qingdao Changsheng Dongfang Industry Group Co., Ltd.

Address before: Pudong solar energy industry base in Jimo city of Shandong Province, Qingdao City, 266234

Patentee before: Qingdao Longsheng Crystalline Silicon Science & Technology Co., Ltd.

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Effective date of registration: 20171124

Address after: Miao road Laoshan District 266061 Shandong city of Qingdao Province, No. 52 906

Patentee after: Qingdao Changsheng Electric Design Institute Co. Ltd.

Address before: 1 road 266000 in Shandong province Qingdao city Laoshan District No. 1 Keyuan latitude B block 7 layer B4-2

Patentee before: Qingdao Changsheng Dongfang Industry Group Co., Ltd.

CF01 Termination of patent right due to non-payment of annual fee
CF01 Termination of patent right due to non-payment of annual fee

Granted publication date: 20140709

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