CN103741206A - Polycrystalline silicon ingot casting molten material and impurity removing process - Google Patents
Polycrystalline silicon ingot casting molten material and impurity removing process Download PDFInfo
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Abstract
The invention discloses a polycrystalline silicon ingot casting molten material and an impurity removing process. The process comprises the following steps: 1, preheating: adopting an ingot furnace to preheat a silicon material filled in a crucible, and gradually raising the heating temperature of the ingot furnace to T1; the preheating time is 6-10h, and T1=1165-1185 DEG C; 2, melting: the melting temperature is T1-T5; T5=1540-1560 DEG C; in the melting process, filling insert gases into the ingot furnace, and keeping air pressure in the furnace in Q1, and Q1=550-650mbar; 3, removing impurities: the process is as follows: the 11th step, reducing pressure: the air pressure of the ingot furnace is reduced from Q1 to Q2, and the pressure reducing time is 8-12min, and Q2=350-450mbar; the 12th step, maintaining pressure; the 13th step, boosting pressure and lowering temperature. The process has the advantages of simple steps, reasonable design, convenience in realization, easiness in grasp and good using effect, can discharge gas containing carbon in the furnace in time, and increases the polycrystalline silicon ingot casting quality.
Description
Technical field
The invention belongs to polycrystalline silicon ingot casting technical field, especially relate to a kind of polycrystalline silicon ingot casting melt and impurities removal technique.
Background technology
Photovoltaic generation is one of current most important clean energy, has great development potentiality.The key factor of restriction photovoltaic industry development, is that electricity conversion is low on the one hand, is high expensive on the other hand.Photovoltaic silicon wafer is the basic material of producing solar cell and assembly, must be more than 6N level (being that non-silicon content of impurities is below 1ppm) for the production of the polysilicon purity of photovoltaic silicon wafer, otherwise the performance of photovoltaic cell will be subject to very large negative impact.In recent years, polysilicon chip production technology has had marked improvement, polycrystalline cast ingot technology from heavily approximately 270 kilograms of each silicon ingots of G4(, can be cut 4 * 4=16 silicon side) progressive to G5 (5 * 5=25 silicon side), then progressive to G6 (6 * 6=36 silicon side) again.And the unit volume of the polycrystalline silicon ingot casting of producing progressively increases, yield rate increases, and the manufacturing cost of unit volume polycrystalline silicon ingot casting progressively reduces.At present, how producing the polycrystalline silicon ingot casting that volume is larger, is the important measures that reduce manufacturing cost.
In actual production process, during solar energy polycrystalline silicon ingot casting, need load silicon material with quartz crucible, and silicon material is dropped into after quartz crucible, generally also need, through preheating, fusing (also claiming melt), long brilliant (also weighed to solidification and crystallization), annealing, the step such as cooling, just can complete polycrystalline silicon ingot casting process.In polycrystalline cast ingot process, because at high temperature reacting, the thermal field (generally adopting graphite material) of ingot furnace furnace chamber inside, quartz crucible etc. can produce carbonaceous gas, as CO, CO
2deng, if carbonaceous gas discharges not in time, will enter melted silicon, cause melted silicon to form impurity or the defects such as carbon deposits, SiC inclusion in the long brilliant process of directional freeze, this not only can cause increasing in polysilicon cutting technique broken string accident and produce stria bad, but also can cause that finished product cell piece leakage rate is high, efficiency of conversion is low, thereby need carry out impurities removal.Nowadays, conventional sundries discharging method is at ingot furnace top, to pass into rare gas element (as argon gas) to discharge the carbonaceous gas being produced.But in actual melt process, gas in ingot furnace can not be discharged thermal field by air outlet at once, but can in the unitized construction of the compositions such as crucible, backplate, cover plate, circulate, and enters melted silicon surface, carbon is adsorbed and dissolves in melted silicon, corresponding SiC, the Si of making
3n
4deng impurity, enter silicon ingot, thereby cause the carbon content of the silicon ingot growing high, cause casting defect, impact section yield rate, and finally cause cell piece poor efficiency.
Summary of the invention
Technical problem to be solved by this invention is for above-mentioned deficiency of the prior art, a kind of polycrystalline silicon ingot casting melt and impurities removal technique are provided, its method steps is simple, reasonable in design, realization is convenient and be easy to grasp, result of use is good, carbonaceous gas in stove can be discharged in time, and effectively improve polycrystalline silicon ingot casting quality.
For solving the problems of the technologies described above, the technical solution used in the present invention is: a kind of polycrystalline silicon ingot casting melt and impurities removal technique, is characterized in that this technique comprises the following steps:
Step 1, preheating: adopt ingot furnace to carry out preheating to the silicon material being loaded in crucible, and the Heating temperature of described ingot furnace is progressively promoted to T1; Be 6h～10h warm up time, wherein T1=1165 ℃～1185 ℃;
Step 2, fusing: adopt described ingot furnace to melt the silicon material being loaded in crucible, until the silicon material in crucible all melts; Temperature of fusion is T1～T5; Wherein T5=1540 ℃～1560 ℃;
In this step, in melting process, in described ingot furnace, be filled with rare gas element and described ingot furnace internal gas pressure is remained on to Q1, wherein Q1=550mbar～650mbar;
Step 3, impurities removal, process is as follows:
The 11st step, step-down: the heating and temperature control of described ingot furnace, at T5, and is down to Q2 by the air pressure of described ingot furnace by Q1, and the step-down time is 8min～12min; Wherein, Q2=350mbar～450mbar;
The 12nd step, pressurize: the heating and temperature control of described ingot furnace, at T5, and is remained on to Q2 by described ingot furnace internal gas pressure, and the dwell time is 10min～60min;
The 13rd step, boost and lower the temperature: first the air pressure of described ingot furnace is risen to Q1 by Q2, then the Heating temperature of described ingot furnace is down to T6 gradually by T5, wherein T6 is polysilicon crystal temperature and T6=1420 ℃～1440 ℃.
Above-mentioned a kind of polycrystalline silicon ingot casting melt and impurities removal technique, is characterized in that: in the 12nd step, the dwell time is 25min～35min.
Above-mentioned a kind of polycrystalline silicon ingot casting melt and impurities removal technique, is characterized in that: Q1=600mbar in step 2, Q2=400mbar in the 11st step.
Above-mentioned a kind of polycrystalline silicon ingot casting melt and impurities removal technique, is characterized in that: be 8min～12min the pressure rising time that in the 13rd step, the air pressure of described ingot furnace is risen to Q1 by Q2, and the temperature fall time that the Heating temperature of described ingot furnace is down to T6 gradually by T5 is 1h～2h.
Above-mentioned a kind of polycrystalline silicon ingot casting melt and impurities removal technique, is characterized in that: in step 3, required total time of impurities removal process is 2.4h～2.6h.
Above-mentioned a kind of polycrystalline silicon ingot casting melt and impurities removal technique, it is characterized in that: in step 2 until the silicon material in crucible all after fusing, first by the heating and temperature control of described ingot furnace at T5, the heating power of described ingot furnace starts to decline afterwards, heating power until described ingot furnace stops after decline and time length t, and melt process completes; Then enter step 3 then; T=18min～22min wherein.
Above-mentioned a kind of polycrystalline silicon ingot casting melt and impurities removal technique, is characterized in that: in step 1, in warm, the heating power of described ingot furnace is progressively increased to P1, wherein P1=70kW～80kW; Silicon material described in step 2 in crucible all after fusing, is observed the heating power changing conditions of described ingot furnace, treats that the heating power of described ingot furnace drops to P2, and keeps after the constant and time length t of P2, and melt process completes; Wherein, P2=35kW～45kW.
Above-mentioned a kind of polycrystalline silicon ingot casting melt and impurities removal technique, is characterized in that: while melting in step 2, process is as follows:
The 1st step, insulation: the heating and temperature control of described ingot furnace, at T1, and is incubated to 0.4h～0.6h;
The 2nd step to the 5 steps, intensification and pressurization: by first extremely rear minute four steps, the Heating temperature of described ingot furnace is promoted to T2 gradually by T1, the heating-up time is 0.4h～0.6h; In temperature-rise period, in described ingot furnace, be filled with rare gas element and the air pressure of described ingot furnace is progressively promoted to Q1; Wherein, T2=1190 ℃～1210 ℃;
The 6th step, heat up and pressurize for the first time: the Heating temperature of described ingot furnace is promoted to T3 gradually by T2 and the heating-up time is 3.5h～4.5h, the internal gas pressure of ingot furnace described in temperature-rise period remains on Q1; Wherein, T3=1440 ℃～1460 ℃;
The 7th step: heat up for the second time and pressurize: the Heating temperature of described ingot furnace is promoted to T4 gradually by T3 and the heating-up time is 3.5h～4.5h, the internal gas pressure of ingot furnace described in temperature-rise period remains on Q1; Wherein, T4=1490 ℃～1510 ℃;
The 8th step, heat up and pressurize for the third time: the Heating temperature of described ingot furnace is promoted to T5 gradually by T4 and the heating-up time is 3.5h～4.5h, the internal gas pressure of ingot furnace described in temperature-rise period remains on Q1; Wherein, T5=1540 ℃～1560 ℃;
The 9th step, insulation: the heating and temperature control of described ingot furnace, at T5, and is incubated to 3.5h～4.5h; In insulating process, described ingot furnace internal gas pressure remains on Q1;
The 10th step, continue insulation: the heating and temperature control of described ingot furnace, at T5, and is incubated to 4h～8h, until the silicon material in crucible all melts; In insulating process, described ingot furnace internal gas pressure remains on Q1.
Above-mentioned a kind of polycrystalline silicon ingot casting melt and impurities removal technique, is characterized in that: ingot furnace described in step 1 is G5 type ingot furnace.
Above-mentioned a kind of polycrystalline silicon ingot casting melt and impurities removal technique, it is characterized in that: when in the 2nd step to the 5 steps, by elder generation, extremely within rear minute, four steps are promoted to T2 by the Heating temperature of described ingot furnace gradually by T1, each step promotes 5 ℃～8 ℃ of temperature, and each step lifting all needs 5min～12min; In the 6th step, heat up for the first time and pressure maintaining period in, in the 7th step, heat up for the second time and pressure maintaining period in, in the 8th step, heat up for the third time and pressure maintaining period neutralization the 9th step in carry out in insulating process, all need the heating power changing conditions of described ingot furnace to observe, and guarantee that the heating power of described ingot furnace changes steadily.
The present invention compared with prior art has the following advantages:
1, reasonable in design and treatment process steps is simple, be easy to grasp.
2, input cost low and realize convenient.
3, use easy to operate and melting process end point to hold accurately, in melting process, after the silicon material in crucible all melts, the Heating temperature of controlling ingot furnace remains unchanged, and the time dependent curve of the heating power of ingot furnace (being powertrace) is observed; Wherein, until the silicon material in crucible, all after fusing, the powertrace of ingot furnace starts to decline, and until the powertrace of ingot furnace, declines and walks after flat 20min, and melt process completes, and grows afterwards the brilliant stage.In actual mechanical process, by observed power curve, just can accurately determine the time point that melt process completes, by the fusion stage, be switched to some switching time in long brilliant stage.Actually operating is easy, and realizes conveniently, can accurately hold the switching time that is switched to the long brilliant stage by the fusion stage.That is to say, the present invention stablizes ingot casting melt curve by extending the melt time, the brilliant stage of incision length again after powertrace is walked flat 20min, thereby can accurately be melted to the switching time in long brilliant stage, stopped due to problems such as polycrystalline silicon ingot casting Quality Down that melt deficiency of time or melt overlong time cause, cost risings simultaneously.And, after adopting the present invention accurately to hold melt in polycrystalline silicon ingot casting process to long brilliant switching time, the efficiency of conversion that can guarantee to grow brilliant quality and finally make cell piece.
4, melting process divides ten steps to carry out, reasonable in design, realize convenient and result of use is good, can effectively improve long crystalloid amount, reduces sticky crucible rate, improves the efficiency of conversion of solar battery sheet, can effectively improve yield rate.
5, sundries discharging method is simple, reasonable in design and impurities removal is effective, reduce rapidly stove internal gas pressure, and fast reducing air pressure contributes to discharge fast foreign gas in the 11st step, suppresses contacting and absorption of carbonaceous gas and melted silicon; Contribute to further to promote the fusing of silicon liquid simultaneously.And, in the 11st step, reduce after stove internal gas pressure rapidly, in the 12nd step, in pressurize 10～60min process, make carbon-containing impurities in gas no longer at body of heater internal recycle, strengthen the convection current of melt and bath surface, make its abundant impurities removal, impurity is along with air-flow is discharged body of heater.Thereby, by the impurities removal operation in step 3 of the present invention, can effectively reduce the inner impurity of furnace chamber, in the long brilliant stage, be easy to obtain higher pure environment of crystal growth, thereby can effectively improve the yield rate of silicon ingot and the whole efficiency of conversion of solar battery sheet, this sundries discharging method is easy to operate, practical, is convenient to batch production.Thereby, impurities removal technique of the present invention can effectively reduce the carbon content in silicon ingot process of growth (i.e. long brilliant stage), thereby make the silicon ingot of growth have higher quality, and thereby the generation that can effectively reduce hard point improves silicon ingot yield rate, and reduce wire breaking during cutting of silicon wafers rate, improve solar battery sheet yield rate and efficiency of conversion, this sundries discharging method is easy to operate, practical, is convenient to batch production.
In sum, the inventive method step is simple, reasonable in design, realization is convenient and be easy to grasp, result of use is good, carbonaceous gas in stove can be discharged in time, and effectively improve polycrystalline silicon ingot casting quality.
Below by drawings and Examples, technical scheme of the present invention is described in further detail.
Accompanying drawing explanation
Fig. 1 is process flow diagram of the present invention.
Temperature and power when Fig. 2 carries out polycrystalline silicon ingot casting for employing the present invention.
Embodiment
Embodiment 1
A kind of polycrystalline silicon ingot casting melt and impurities removal technique as shown in Figure 1, comprise the following steps:
Step 1, preheating: adopt ingot furnace to carry out preheating to the silicon material being loaded in crucible, and the Heating temperature of described ingot furnace is progressively promoted to T1; Be 7h, wherein T1=1175 ℃ warm up time.
In the present embodiment, described ingot furnace is G5 type ingot furnace.And described ingot furnace is specially the G5 type ingot furnace that Zhejiang Jingsheng Electrical and Mechanical Co., Ltd. produces.Described crucible is that quartz crucible and its are G5 crucible, and the polycrystalline silicon ingot casting of producing is G5 ingot.
During actual use, the charge amount of described quartz crucible is 600kg left and right.
In the present embodiment, the charge amount of described quartz crucible is 560kg.In actual use procedure, can according to specific needs, the charge amount of described quartz crucible be adjusted accordingly.
In the present embodiment, in step 1, in warm, the heating power of described ingot furnace is progressively increased to P1, wherein P1=75kW.
And, in warm, the heating power of described ingot furnace is progressively promoted to P1 with the rate of rise of (10～15) kW/h.
Actual while carrying out preheating, can according to specific needs, the value size of the rate of rise of heating power in warm up time, warm and T1 and P1 be adjusted accordingly.
Step 2, fusing: adopt described ingot furnace to melt the silicon material being loaded in crucible, temperature of fusion is T1～T5; T5=1550 ℃ wherein.
In this step, in melting process, in described ingot furnace, be filled with rare gas element and described ingot furnace internal gas pressure is remained on to Q1, wherein Q1=600mbar.In the present embodiment, described rare gas element is argon gas.
In the present embodiment, until the silicon material in crucible, all after fusing, by the heating and temperature control of described ingot furnace, at T5, the heating power of described ingot furnace starts to decline afterwards, until the heating power of described ingot furnace stop declining and time length t after, melt process completes; T=20min wherein.
During actual fusing, can according to specific needs, the value size of T5, t and Q1 be adjusted accordingly.
Step 3, impurities removal, process is as follows:
The 11st step, step-down: the heating and temperature control of described ingot furnace, at T5, and is down to Q2 by the air pressure of described ingot furnace by Q1, and the step-down time is 10min; Wherein, Q2=400mbar.
The 12nd step, pressurize: the heating and temperature control of described ingot furnace, at T5, and is remained on to Q2 by described ingot furnace internal gas pressure, and the dwell time is 30min.
The 13rd step, boost and lower the temperature: first the air pressure of described ingot furnace is risen to Q1 by Q2, then the Heating temperature of described ingot furnace is down to T6 gradually by T5, wherein T6 is polysilicon crystal temperature and T6=1420 ℃～1440 ℃.
In the present embodiment, be 8min～12min the pressure rising time that in the 13rd step, the air pressure of described ingot furnace is risen to Q1 by Q2, and the temperature fall time that the Heating temperature of described ingot furnace is down to T6 gradually by T5 is 1h～2h.
Actual while carrying out impurities removal, can according to specific needs, the value size of step-down time, dwell time, pressure rising time and temperature fall time and Q2 be adjusted accordingly.
In the present embodiment, in step 3, required total time of impurities removal process is 2.5h.
When the 11st step is carried out step-down, by reducing the flow of described rare gas element, carry out step-down; When the 13rd step is boosted, by increasing the flow of described rare gas element, boost.
In the 11st step, reduce rapidly stove internal gas pressure, and fast reducing air pressure contributes to discharge fast foreign gas, inhibition carbonaceous gas contacts and absorption with melted silicon; Contribute to further to promote the fusing of silicon liquid simultaneously.And, in the 11st step, reduce after stove internal gas pressure rapidly, in the 12nd step, in pressurize 30min process, make carbon-containing impurities in gas no longer at body of heater internal recycle, strengthen the convection current of melt and bath surface, make its abundant impurities removal, impurity is along with air-flow is discharged body of heater.Thereby, by the impurities removal operation in step 3 of the present invention, can effectively reduce the inner impurity of furnace chamber, in the long brilliant stage, be easy to obtain higher pure environment of crystal growth, thereby can effectively improve the yield rate of silicon ingot and the whole efficiency of conversion of solar battery sheet, this sundries discharging method is easy to operate, practical, is convenient to batch production.
In the present embodiment, in step 2, until the silicon material in crucible all after fusing, the heating and temperature control of described ingot furnace, at T5, and is observed the time dependent curve of the heating power of described ingot furnace (being powertrace), referred to Fig. 2.In Fig. 2, the time dependent curve of heating power that fine line is described ingot furnace, needing solid line is the time dependent curve of Heating temperature of described ingot furnace, vertical line is the alarming line of the silicon material in crucible while all melting.As seen from Figure 2, after the silicon material in crucible all melts, the powertrace of described ingot furnace starts to decline, powertrace until described ingot furnace declines and walks after flat 20min, and melt process completes, and enters afterwards the impurities removal stage, until the impurities removal stage proportionately after, then enter long brilliant; It is the time point that the A point in Fig. 2 completes for melt process.
In actual mechanical process, by observed power curve, just can accurately determine the time point that melt process completes, by the fusion stage, be switched to the impurities removal stage (wherein, the impurities removal stage also can be regarded the operation in early stage in long brilliant stage as) some switching time, by the present invention, can accurately hold and be switched to the impurities removal stage by the fusion stage, and the switching from the impurities removal stage to the long brilliant stage is actual, actually operating is easy, and realizes conveniently.That is to say, by the present invention, can accurately grasp the end time point of melt process, to solve the problem of the polycrystalline silicon ingot casting Quality Down of being produced causing because of melt deficiency of time or melt overlong time, wherein during melt deficiency of time, may cause the fusing of silicon material abundant not, cause the silicon ingot life-span abnormal; And if melt overlong time will make quartz crucible for a long time in hot stage, to silicon nitride coating, may cause damage, cause sticky crucible.
In the present embodiment, silicon material described in step 2 in crucible all after fusing, is observed the heating power changing conditions of described ingot furnace, treats that the heating power of described ingot furnace drops to P2, and keeps after the constant and time length t of P2, and melt process completes; Wherein, P2=40kW.
During actual fusing, according to the difference of charge amount in described crucible, the size of P2 is corresponding to be adjusted within the scope of 35kW～45kW.
In the present embodiment, while melting in step 2, process is as follows:
The 1st step, insulation: the heating and temperature control of described ingot furnace, at T1, and is incubated to 0.5h.
The 2nd step to the 5 steps, intensification and pressurization: by first extremely rear minute four steps, the Heating temperature of described ingot furnace is promoted to T2 gradually by T1, the heating-up time is that the total time of the 2nd step to the 5 steps is 0.5h to 0.5h(); In temperature-rise period, in described ingot furnace, be filled with rare gas element and the air pressure of described ingot furnace is progressively promoted to Q1; Wherein, T2=1200 ℃.
In the 2nd step to the 5 steps, by first when within rear minute, four steps are promoted to T2 by the Heating temperature of described ingot furnace gradually by T1, each step promotes 5 ℃～8 ℃ of temperature, and each step promotes and all needs 5min～10min.
The 6th step, heat up and pressurize for the first time: the Heating temperature of described ingot furnace is promoted to T3 gradually by T2 and the heating-up time is 4h, the internal gas pressure of ingot furnace described in temperature-rise period remains on Q1; Wherein, T3=1450 ℃.
The 7th step: heat up for the second time and pressurize: the Heating temperature of described ingot furnace is promoted to T4 gradually by T3 and the heating-up time is 4h, the internal gas pressure of ingot furnace described in temperature-rise period remains on Q1; Wherein, T4=1500 ℃.
The 8th step, heat up and pressurize for the third time: the Heating temperature of described ingot furnace is promoted to T5 gradually by T4 and the heating-up time is 4h, the internal gas pressure of ingot furnace described in temperature-rise period remains on Q1; Wherein, T5=1550 ℃.
The 9th step, insulation: the heating and temperature control of described ingot furnace, at T5, and is incubated to 4h; In insulating process, described ingot furnace internal gas pressure remains on Q1.
The 10th step, continue insulation: the heating and temperature control of described ingot furnace, at T5, and is incubated to 6h, until the silicon material in crucible all melts; In insulating process, described ingot furnace internal gas pressure remains on Q1.
In the present embodiment, in the 6th step, heat up for the first time and pressure maintaining period in, in the 7th step, heat up for the second time and pressure maintaining period in, in the 8th step, heat up for the third time and pressure maintaining period neutralization the 9th step in carry out in insulating process, all need the heating power changing conditions of described ingot furnace to observe, and guarantee that the heating power of described ingot furnace changes steadily.
That is to say, while melting in the 6th step to the 9 steps, must make powertrace steadily advance, can not occur comparatively significantly sags and crests, can bring increasing of hard point like this.
In the present embodiment, when heating up and pressurizeing in the 2nd step to the 5 steps, process is as follows:
The 2nd step, the first step promote: the Heating temperature of described ingot furnace is promoted to 1182 ℃ by 1175 ℃, and the heating-up time is 7min.
The 3rd step, second step promote: the Heating temperature of described ingot furnace is promoted to 1190 ℃ by 1182 ℃, and the heating-up time is 8min.
The 4th step, the 3rd step promote: the Heating temperature of described ingot furnace is promoted to 1195 ℃ by 1190 ℃, and the heating-up time is 5min.
The 5th step, the 4th step promote: the Heating temperature of described ingot furnace is promoted to 1200 ℃ by 1195 ℃, and the heating-up time is 5min.
In the present embodiment, in the 10th step, until the whole fusings of the silicon material in crucible and described ingot furnace, send after " fusing completes warning ", need manual intervention, decline situation to powertrace is observed, powertrace until described ingot furnace declines and walks after flat 20min, melt process completes, and manual intervention afterwards will be cut into the long brilliant stage fusion stage.
In the present embodiment, any surface finish, the inclusion-free of institute's machine-shaping polycrystalline silicon ingot casting, without sticky crucible phenomenon, minority carrier life time >5.0us (microsecond), hard point ratio <0.5%, yield rate is 71%.Use institute's machine-shaping polycrystalline silicon ingot casting to make the rear stria ratio <0.5% of silicon chip section, solar battery sheet efficiency of conversion can improve 0.1%.
Embodiment 2
In the present embodiment, as different from Example 1: in step 1, be 6h and T1=1185 ℃ warm up time, P1=80kW; T5=1560 ℃ in step 2, t=18min, Q1=650mbar; In the 1st step, soaking time is 0.4h; T2=1210 ℃ in the 2nd step to the 5 steps, the heating-up time is 0.4h; In the 6th step, T3=1460 ℃ and heating-up time are 3.5h; In the 7th step, T4=1510 ℃ and heating-up time are 3.5h; In the 8th step, T5=1560 ℃ and heating-up time are 3.5h; In the 9th step, soaking time is 3.5h; In the 10th step, soaking time is 4h.
In the present embodiment, when heating up and pressurizeing in the 2nd step to the 5 steps, process is as follows:
The 2nd step, the first step promote: the Heating temperature of described ingot furnace is promoted to 1190 ℃ by 1185 ℃, and the heating-up time is 5min.
The 3rd step, second step promote: the Heating temperature of described ingot furnace is promoted to 1195 ℃ by 1190 ℃, and the heating-up time is 5min.
The 4th step, the 3rd step promote: the Heating temperature of described ingot furnace is promoted to 1205 ℃ by 1195 ℃, and the heating-up time is 9min.
The 5th step, the 4th step promote: the Heating temperature of described ingot furnace is promoted to 1210 ℃ by 1205 ℃, and the heating-up time is 5min.
While carrying out impurities removal in step 3, in the 11st step, the step-down time is 8min and Q2=450mbar; In the 12nd step, the dwell time is 60min; In the 13rd step, be 8min pressure rising time.
In the present embodiment, in step 3, required total time of impurities removal process is 2.6h.
In the present embodiment, all the other processing steps and processing parameter are all identical with embodiment 1.
In the present embodiment, any surface finish, the inclusion-free of institute's machine-shaping polycrystalline silicon ingot casting, without sticky crucible phenomenon, minority carrier life time >5.0us (microsecond), hard point ratio <0.5%, yield rate is 71%.Use institute's machine-shaping polycrystalline silicon ingot casting to make the rear stria ratio <0.5% of silicon chip section, solar battery sheet efficiency of conversion can improve 0.1%.
Embodiment 3
In the present embodiment, as different from Example 1: in step 1, be 10h and T1=1165 ℃ warm up time, P1=70kW; T5=1540 ℃ in step 2, t=22min, Q1=550mbar; In the 1st step, soaking time is 0.6h; T2=1190 ℃ in the 2nd step to the 5 steps, the heating-up time is 0.6h; In the 6th step, T3=1440 ℃ and heating-up time are 4.5h; In the 7th step, T4=1490 ℃ and heating-up time are 4.5h; In the 8th step, T5=1540 ℃ and heating-up time are 4.5h; In the 9th step, soaking time is 4.5h; In the 10th step, soaking time is 8h.
In the present embodiment, when heating up and pressurizeing in the 2nd step to the 5 steps, process is as follows:
The 2nd step, the first step promote: the Heating temperature of described ingot furnace is promoted to 1172 ℃ by 1165 ℃, and the heating-up time is 9min.
The 3rd step, second step promote: the Heating temperature of described ingot furnace is promoted to 1178 ℃ by 1172 ℃, and the heating-up time is 8min.
The 4th step, the 3rd step promote: the Heating temperature of described ingot furnace is promoted to 1183 ℃ by 1178 ℃, and the heating-up time is 10min.
The 5th step, the 4th step promote: the Heating temperature of described ingot furnace is promoted to 1190 ℃ by 1183 ℃, and the heating-up time is 9min.
While carrying out impurities removal in step 3, in the 11st step, the step-down time is 12min and Q2=350mbar; In the 12nd step, the dwell time is 35min; In the 13rd step, be 12min pressure rising time.
In the present embodiment, in step 3, required total time of impurities removal process is 2.4h.
In the present embodiment, all the other processing steps and processing parameter are all identical with embodiment 1.
In the present embodiment, any surface finish, the inclusion-free of institute's machine-shaping polycrystalline silicon ingot casting, without sticky crucible phenomenon, minority carrier life time >5.0us (microsecond), hard point ratio <0.5%, yield rate is 70%.Use institute's machine-shaping polycrystalline silicon ingot casting to make the rear stria ratio <0.5% of silicon chip section, solar battery sheet efficiency of conversion can improve 0.05%.
Embodiment 4
In the present embodiment, as different from Example 1: while carrying out impurities removal in step 3, in the 11st step, the step-down time is 10min and Q2=380mbar; In the 12nd step, the dwell time is 25min; In the 13rd step, be 10min pressure rising time.
In the present embodiment, in step 3, required total time of impurities removal process is 2.5h.
In the present embodiment, all the other processing steps and processing parameter are all identical with embodiment 1.
In the present embodiment, any surface finish, the inclusion-free of institute's machine-shaping polycrystalline silicon ingot casting, without sticky crucible phenomenon, minority carrier life time >5.0us (microsecond), hard point ratio <0.5%, yield rate is 70%.Use institute's machine-shaping polycrystalline silicon ingot casting to make the rear stria ratio <0.5% of silicon chip section, solar battery sheet efficiency of conversion can improve 0.1%.
Embodiment 5
In the present embodiment, as different from Example 1: while carrying out impurities removal in step 3, in the 11st step, the step-down time is 10min and Q2=450mbar; In the 12nd step, the dwell time is 10min; In the 13rd step, be 10min pressure rising time.
In the present embodiment, in step 3, required total time of impurities removal process is 2.5h.
In the present embodiment, all the other processing steps and processing parameter are all identical with embodiment 1.
In the present embodiment, any surface finish, the inclusion-free of institute's machine-shaping polycrystalline silicon ingot casting, without sticky crucible phenomenon, minority carrier life time >5.0us (microsecond), hard point ratio <0.5%, yield rate is 70%.Use institute's machine-shaping polycrystalline silicon ingot casting to make the rear stria ratio <0.5% of silicon chip section, solar battery sheet efficiency of conversion can improve 0.05%.
The above; it is only preferred embodiment of the present invention; not the present invention is imposed any restrictions, every any simple modification of above embodiment being done according to the technology of the present invention essence, change and equivalent structure change, and all still belong in the protection domain of technical solution of the present invention.
Claims (10)
1. polycrystalline silicon ingot casting melt and an impurities removal technique, is characterized in that this technique comprises the following steps:
Step 1, preheating: adopt ingot furnace to carry out preheating to the silicon material being loaded in crucible, and the Heating temperature of described ingot furnace is progressively promoted to T1; Be 6h～10h warm up time, wherein T1=1165 ℃～1185 ℃;
Step 2, fusing: adopt described ingot furnace to melt the silicon material being loaded in crucible, until the silicon material in crucible all melts; Temperature of fusion is T1～T5; Wherein T5=1540 ℃～1560 ℃;
In this step, in melting process, in described ingot furnace, be filled with rare gas element and described ingot furnace internal gas pressure is remained on to Q1, wherein Q1=550mbar～650mbar;
Step 3, impurities removal, process is as follows:
The 11st step, step-down: the heating and temperature control of described ingot furnace, at T5, and is down to Q2 by the air pressure of described ingot furnace by Q1, and the step-down time is 8min～12min; Wherein, Q2=350mbar～450mbar;
The 12nd step, pressurize: the heating and temperature control of described ingot furnace, at T5, and is remained on to Q2 by described ingot furnace internal gas pressure, and the dwell time is 10min～60min;
The 13rd step, boost and lower the temperature: first the air pressure of described ingot furnace is risen to Q1 by Q2, then the Heating temperature of described ingot furnace is down to T6 gradually by T5, wherein T6 is polysilicon crystal temperature and T6=1420 ℃～1440 ℃.
2. according to a kind of polycrystalline silicon ingot casting melt claimed in claim 1 and impurities removal technique, it is characterized in that: in the 12nd step, the dwell time is 25min～35min.
3. according to a kind of polycrystalline silicon ingot casting melt and impurities removal technique described in claim 1 or 2, it is characterized in that: Q1=600mbar in step 2, Q2=400mbar in the 11st step.
4. according to a kind of polycrystalline silicon ingot casting melt and impurities removal technique described in claim 1 or 2, it is characterized in that: be 8min～12min the pressure rising time that in the 13rd step, the air pressure of described ingot furnace is risen to Q1 by Q2, the temperature fall time that the Heating temperature of described ingot furnace is down to T6 gradually by T5 is 1h～2h.
5. according to a kind of polycrystalline silicon ingot casting melt and impurities removal technique described in claim 1 or 2, it is characterized in that: in step 3, required total time of impurities removal process is 2.4h～2.6h.
6. according to a kind of polycrystalline silicon ingot casting melt and impurities removal technique described in claim 1 or 2, it is characterized in that: in step 2 until the silicon material in crucible all after fusing, first by the heating and temperature control of described ingot furnace at T5, the heating power of described ingot furnace starts to decline afterwards, heating power until described ingot furnace stops after decline and time length t, and melt process completes; Then enter step 3 then; T=18min～22min wherein.
7. according to a kind of polycrystalline silicon ingot casting melt claimed in claim 6 and impurities removal technique, it is characterized in that: in step 1, in warm, the heating power of described ingot furnace is progressively increased to P1, wherein P1=70kW～80kW; Silicon material described in step 2 in crucible all after fusing, is observed the heating power changing conditions of described ingot furnace, treats that the heating power of described ingot furnace drops to P2, and keeps after the constant and time length t of P2, and melt process completes; Wherein, P2=35kW～45kW.
8. according to a kind of polycrystalline silicon ingot casting melt and impurities removal technique described in claim 1 or 2, it is characterized in that: while melting in step 2, process is as follows:
The 1st step, insulation: the heating and temperature control of described ingot furnace, at T1, and is incubated to 0.4h～0.6h;
The 2nd step to the 5 steps, intensification and pressurization: by first extremely rear minute four steps, the Heating temperature of described ingot furnace is promoted to T2 gradually by T1, the heating-up time is 0.4h～0.6h; In temperature-rise period, in described ingot furnace, be filled with rare gas element and the air pressure of described ingot furnace is progressively promoted to Q1; Wherein, T2=1190 ℃～1210 ℃;
The 6th step, heat up and pressurize for the first time: the Heating temperature of described ingot furnace is promoted to T3 gradually by T2 and the heating-up time is 3.5h～4.5h, the internal gas pressure of ingot furnace described in temperature-rise period remains on Q1; Wherein, T3=1440 ℃～1460 ℃;
The 7th step: heat up for the second time and pressurize: the Heating temperature of described ingot furnace is promoted to T4 gradually by T3 and the heating-up time is 3.5h～4.5h, the internal gas pressure of ingot furnace described in temperature-rise period remains on Q1; Wherein, T4=1490 ℃～1510 ℃;
The 8th step, heat up and pressurize for the third time: the Heating temperature of described ingot furnace is promoted to T5 gradually by T4 and the heating-up time is 3.5h～4.5h, the internal gas pressure of ingot furnace described in temperature-rise period remains on Q1; Wherein, T5=1540 ℃～1560 ℃;
The 9th step, insulation: the heating and temperature control of described ingot furnace, at T5, and is incubated to 3.5h～4.5h; In insulating process, described ingot furnace internal gas pressure remains on Q1;
The 10th step, continue insulation: the heating and temperature control of described ingot furnace, at T5, and is incubated to 4h～8h, until the silicon material in crucible all melts; In insulating process, described ingot furnace internal gas pressure remains on Q1.
9. according to a kind of polycrystalline silicon ingot casting melt and impurities removal technique described in claim 1 or 2, it is characterized in that: ingot furnace described in step 1 is G5 type ingot furnace.
10. according to a kind of polycrystalline silicon ingot casting melt claimed in claim 8 and impurities removal technique, it is characterized in that: when in the 2nd step to the 5 steps, by elder generation, extremely within rear minute, four steps are promoted to T2 by the Heating temperature of described ingot furnace gradually by T1, each step promotes 5 ℃～8 ℃ of temperature, and each step lifting all needs 5min～12min; In the 6th step, heat up for the first time and pressure maintaining period in, in the 7th step, heat up for the second time and pressure maintaining period in, in the 8th step, heat up for the third time and pressure maintaining period neutralization the 9th step in carry out in insulating process, all need the heating power changing conditions of described ingot furnace to observe, and guarantee that the heating power of described ingot furnace changes steadily.
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| CN106087041A (en) * | 2016-06-17 | 2016-11-09 | 江西赛维Ldk太阳能高科技有限公司 | A kind of method removing polysilicon impurity during ingot casting |
| CN106435726A (en) * | 2016-11-17 | 2017-02-22 | 江苏美科硅能源有限公司 | Material melting process for ingot casting of polycrystal furnace |
| CN107130296A (en) * | 2017-05-03 | 2017-09-05 | 四川欣蓝光电科技有限公司 | A kind of polycrystalline silicon manufacture craft |
| CN107142518A (en) * | 2017-04-28 | 2017-09-08 | 山西潞安太阳能科技有限责任公司 | A kind of material technique of polycrystalline silicon ingot casting |
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| CN108315813A (en) * | 2018-01-04 | 2018-07-24 | 晶科能源有限公司 | A kind of preparation method of polycrystalline silicon ingot casting |
| CN109208072A (en) * | 2018-05-31 | 2019-01-15 | 扬州续笙新能源科技有限公司 | A kind of method for crystallising improving polycrystalline silicon ingot casting bottom crystalline substance flower |
| CN116411338A (en) * | 2023-06-12 | 2023-07-11 | 内蒙古晶环电子材料有限公司 | Material boiling process for producing sapphire single crystal |
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