CN106283182A

CN106283182A - A kind of polycrystalline silicon casting ingot process

Info

Publication number: CN106283182A
Application number: CN201610694941.9A
Authority: CN
Inventors: 刘波波; 贺鹏; 虢虎平; 史燕凯
Original assignee: XI'AN HUAJING ELECTRONIC TECHNOLOGY Co Ltd
Current assignee: XI'AN HUAJING ELECTRONIC TECHNOLOGY Co Ltd
Priority date: 2016-08-19
Filing date: 2016-08-19
Publication date: 2017-01-04
Anticipated expiration: 2036-08-19
Also published as: CN106283182B

Abstract

The invention discloses a kind of polycrystalline silicon casting ingot process, comprise the following steps: one, auxiliary heater is installed: auxiliary heater is installed in polycrystalline silicon ingot or purifying furnace；Auxiliary heater is to be laid in the bottom heater below crucible；Two, charging；Three, preheating；Four, fusing, process is as follows: 401, hexahedro add heat fusing；402, five faces add heat fusing；403, subsequent melting；Five, to long brilliant pre-treatment after fusing, process is as follows: 501, cooling；502, heat up；Six, long crystalline substance；Seven, anneal and cool down: after long brilliant process completes in step 6, anneal and cool down, and obtaining the polycrystalline silicon ingot casting of machine-shaping.Present invention process step is simple, reasonable in design and realization is easy, using effect is good, use hexahedro heater to heat, simultaneously by brilliant pre-treatment step the longest after setting up fusing, and crystal growing technology is adjusted, grain size can be effectively reduced, improve the quality of ingot casting finished product.

Description

A kind of polycrystalline silicon casting ingot process

Technical field

The invention belongs to polycrystalline silicon ingot casting technical field, especially relate to a kind of polycrystalline silicon casting ingot process.

Background technology

Photovoltaic generation is one of currently the most important clean energy resource, has great development potentiality.Restriction photovoltaic industry is sent out The key factor of exhibition, is on the one hand that electricity conversion is low, is on the other hand high expensive.Photovoltaic silicon wafer is to produce solar-electricity Pond and the stock of assembly, for produce photovoltaic silicon wafer polysilicon purity must (i.e. non-silicon impurity always contains more than 6N level Amount is at below 1ppm), otherwise the performance of photovoltaic cell is by by the biggest negative effect.In recent years, polysilicon chip production technology Having had marked improvement, polycrystalline cast ingot technology arrives from G4 (each silicon ingot weighs about 270 kilograms, can cut 4 × 4=16 silicon side) progress G5 (5 × 5=25 silicon side) is the most progressive to G6 (6 × 6=36 silicon side).Further, the unit of produced polycrystalline silicon ingot casting Volume incrementally increases, and yield rate increases, and the manufacturing cost of unit volume polycrystalline silicon ingot casting gradually reduces.

In actual production process, during solar energy polycrystalline silicon ingot casting, need to use silica crucible to load silicon material, and by silicon material throw After entering silica crucible, the most also need preheated, fusing (also referred to as melt), long brilliant (also referred to as directional solidification crystallization), annealing, The steps such as cooling, just can complete polycrystalline silicon ingot casting process.Wherein, an extremely important work during annealing is polycrystalline silicon ingot casting Skill step, the bad stress distribution directly affected within ingot casting finished product of annealing effect, the quality to polycrystalline silicon ingot casting finished product Affect bigger.And when making annealing treatment polycrystalline silicon ingot casting at present, the method for neither one unification, standard and specification is available for abiding by Following, actual adding, is inevitably present the problems such as operation is relatively more random, spend time length, annealing effect poor man-hour, thus existing The quality of ingot casting finished product is affected the biggest by some annealing process.Grain size is to represent the yardstick of grain size, and grain size can be used Average area or the average diameter of crystal grain represent.Grain size number is used to represent grain size in commercial production.Model die Degree is divided into 8 grades, and 1-4 level is coarse grain, and 5-8 level is fine grain.At present during polycrystalline silicon ingot casting, neither one is unified, standard And the method (i.e. processing compact grained polycrystalline silicon ingot casting method) of the reduction grain size of specification is available for following, actual add man-hour can not There is the problems such as operation is relatively more random, spend time length, using effect poor with avoiding.

It addition, the heater that existing polycrystalline silicon ingot or purifying furnace is used generally is five heating arrangements, i.e. on the top of crucible Portion and four side-wall outer side are provided with heater, and this five mode of heatings carry out heat radiation, melting efficiency from top to down Relatively low, simultaneously crucible bottom gas be difficult to get rid of, make the oxygen content bottom ingot casting finished product higher.

Summary of the invention

The technical problem to be solved is for above-mentioned deficiency of the prior art, it is provided that a kind of polysilicon casting Ingot technique, its processing step is simple, reasonable in design and realization is easy, using effect is good, uses hexahedro heater to heat, Simultaneously by brilliant pre-treatment step the longest after setting up fusing, and crystal growing technology is adjusted, grain size can be effectively reduced, improve The quality of ingot casting finished product.

For solving above-mentioned technical problem, the technical solution used in the present invention is: a kind of polycrystalline silicon casting ingot process, its feature exists Step is included in, this technique:

Step one, auxiliary heater are installed: install auxiliary heater in polycrystalline silicon ingot or purifying furnace；

Described auxiliary heater is to be laid in the bottom heater below crucible, described crucible be cube crucible and its in Level is laid, and described bottom heater, is laid in the top heater above crucible and four be laid in crucible respectively four The side heater of side-wall outer side forms hexahedro heater；Described top heater and bottom heater are all laid in level, Four described side heater all in vertically to laying；Described top heater, bottom heater and four described sidepiece heating Device is all laid in polycrystalline silicon ingot or purifying furnace；

Step 2, charging: in crucible, load silicon material, and the crucible of built-in silicon material is loaded in polycrystalline silicon ingot or purifying furnace；

Step 3, preheating: top heater, bottom heater and four described side heater are all opened, and uses The silicon material being loaded in crucible is preheated by polycrystalline silicon ingot or purifying furnace, and the heating-up temperature of polycrystalline silicon ingot or purifying furnace is stepped up to T1；Preheating time is 4h～6h, wherein T1=1125 DEG C～1285 DEG C；

Step 4, fusing, process is as follows:

Step 401, the hexahedro heat fusing that adds: use polycrystalline silicon ingot or purifying furnace that the silicon material being loaded in crucible is melted, fusing Temperature is stepped up to T2 by T1；Wherein T2=1350 DEG C～1400 DEG C；In this step, described top heater, bottom-heated Device and four described side heater are in opening；

Step 402, five faces add heat fusing: use polycrystalline silicon ingot or purifying furnace to continue to melt the silicon material being loaded in crucible, Fusion temperature is stepped up to T3 by T2；Wherein T3=1540 DEG C～1560 DEG C；In this step, described top heater and four Described side heater is in opening, and described bottom heater is closed；

Step 403, subsequent melting: after the silicon material in crucible all melts, by the heating-up temperature control of polycrystalline silicon ingot or purifying furnace System is at T3, and the heating power of the most described top heater and four described side heater all begins to decline, and treats described top After the heating power of heater and four described side heater all stops decline and persistent period t, melt process completes；Wherein T=20min～40min；

To long brilliant pre-treatment after step 5, fusing, process is as follows:

Step 501, cooling: the heating-up temperature of polycrystalline silicon ingot or purifying furnace is down to T4 by T3, and is incubated 15min～25min；Its Middle T4=1410 DEG C～1420 DEG C；

Step 502, intensification: the heating-up temperature of polycrystalline silicon ingot or purifying furnace is risen to T5 by T4, and is incubated 8min～15min；Its Middle T5=1435 DEG C～1445 DEG C；

Step 6, long crystalline substance: at T5 and the heating and temperature control of polycrystalline silicon ingot or purifying furnace is carried out directional solidification, until completing long Brilliant process；

Step 7, anneal and cool down: after long brilliant process completes in step 6, anneal and cool down, and obtaining and be processed into The described polycrystalline silicon ingot casting of type.

Above-mentioned a kind of polycrystalline silicon casting ingot process, is characterized in that: top heater described in step one, bottom heater and four Individual described side heater is all connected with heating power adjusting means；

In step 3 in warm, use heating power adjusting means to top heater, bottom heater and four The heating power of described side heater synchronizes to be stepped up；

Described top heater is connected with top firing power supply by the first electrode, and four described side heater all pass through Second electrode is connected with sidepiece heating power supply, and described bottom heater is connected with bottom-heated power supply by the 3rd electrode；Described Top firing power supply, sidepiece heating power supply and bottom-heated power supply are all connected with heating power adjusting means, described heating power Adjusting means is the merit that the output to top firing power supply, sidepiece heating power supply and bottom-heated power supply is adjusted respectively Rate adjusting means.

Above-mentioned a kind of polycrystalline silicon casting ingot process, is characterized in that: in step 3 in warm, by top heater, bottom The heating power of heater and four described side heater synchronizes to be stepped up, and by top heater, bottom-heated The heating power of device and four described side heater is all stepped up to P1, wherein P1=50kW～100kW；

In step 401 in hexahedro heating fusion process, described top heater, bottom heater and four described sidepieces add The heating power of hot device is P1；

In step 402 in five heating fusion processes, described top heater and the heating of four described side heater Power is P1；

In step 403 subsequent melting during, after the silicon material in crucible all melts, described top heater and four The heating power of described side heater synchronizes progressively to decline, and becomes the heating power of top heater or side heater Change situation is observed, and when the heating power of top heater or side heater drops to P2, keeps P2 constant and continues After time t, melt process completes；Wherein, P2=25kW～45kW.

Above-mentioned a kind of polycrystalline silicon casting ingot process, is characterized in that: during carrying out long crystalline substance in step 6, described polycrystalline silicon ingot casting The heat-insulation cage hoisting depth of stove is 8cm/h～12cm/h.

Above-mentioned a kind of polycrystalline silicon casting ingot process, is characterized in that: during carrying out long crystalline substance in step 6, described polycrystalline silicon ingot casting The heating power being positioned at the top heater above crucible in stove is 80kW～95kW, four four sides being laid in crucible respectively The heating power of the side heater outside wall is 30kW～50kW；

Gas chiller it is provided with in polycrystalline silicon ingot or purifying furnace described in step one；During step 6 carries out long crystalline substance, By increasing the cooling gas flow of described gas chiller by the heating and temperature control of polycrystalline silicon ingot or purifying furnace to T5.

Above-mentioned a kind of polycrystalline silicon casting ingot process, is characterized in that: when annealing in step 7 and cool down, and process is as follows:

Step 701, for the first time annealing: through 50min～70min, the heating-up temperature of polycrystalline silicon ingot or purifying furnace is down to T6, and protects Temperature 2h～3h；Wherein, T6=1250 DEG C～1280 DEG C；

Step 702, second time annealing: the heating-up temperature of polycrystalline silicon ingot or purifying furnace is down to T7 by T6 through 50min～70min, And it is incubated 2h～3h；T6=900 DEG C～950 DEG C；

Step 703, cooling: cool to processed polycrystalline silicon ingot casting with the furnace room temperature, it is thus achieved that the described polycrystalline of machine-shaping Silicon ingot casting.

Above-mentioned a kind of polycrystalline silicon casting ingot process, is characterized in that: carry out annealing process neutralization procedure for the first time in step 701 Carry out in 702, in second time annealing process, in described polycrystalline silicon ingot or purifying furnace, being all filled with noble gas and by polycrystalline silicon ingot or purifying furnace Interior air pressure is maintained at Q1, wherein Q1=180Pa～250Pa；

When step 703 cools to processed polycrystalline silicon ingot casting with the furnace room temperature, according to 90 DEG C/h～the cooling of 120 DEG C/h Speed cools down.

Above-mentioned a kind of polycrystalline silicon casting ingot process, is characterized in that: before in step 2, charging is carried out, also need to carry out crucible bottom Prepared by coating, process is as follows:

Step 101, coating spraying liquid are prepared: by organic cementing agent, deionized water and boron nitride by 1: (2～2.5): (0.8 ～1.2) mass ratio uniformly mix, obtain coating spraying liquid；

Step 102, spraying: use spraying equipment by the even application of coating spraying liquid described in step 101 to crucible On bottom surface, portion, 1m in described crucible inner bottom surface²In region, in the described coating spraying liquid of spraying, the quality of contained boron nitride is 100g～200g；

Described crucible is quartz crucible for polycrystalline ingot furnace；

Step 103, drying: crucible described in step 102 is placed horizontally in drying plant, and uses described drying to set Standby and under 80 DEG C～100 DEG C of temperature conditionss, the described coating spraying liquid being sprayed in crucible inner bottom surface is dried, obtain Obtain base coat；

When step 2 feeds, in the crucible of band base coat in load silicon material, and by the crucible of built-in silicon material Load in polycrystalline silicon ingot or purifying furnace.

Above-mentioned a kind of polycrystalline silicon casting ingot process, is characterized in that: organic binder bond described in step 101 is phenolic aldehyde-neoprene rubber Glue adhesive agent, epoxy adhesive, Instant adhesive, acrylic acid adhesive, polyvinyl alcohol adhesive, Polyvinyl acetate adhesive, AE SGA, butvar adhesive stick or glass cement；

Described boron nitride is hexagonal boron nitride.

Above-mentioned a kind of polycrystalline silicon casting ingot process, is characterized in that: when spraying in step 102, described crucible inner bottom surface Upper 1m²In region, in the described coating spraying liquid of spraying, the quality of contained boron nitride is 100g～150g；

When step 103 is dried, first use described drying plant that crucible is heated to 80 DEG C～100 DEG C, then carry out It is incubated till the described coating spraying liquid being sprayed in crucible inner bottom surface is dried.

The present invention compared with prior art has the advantage that

1, step is simple, reasonable in design and realizes conveniently, it is easy to grasping, input cost is relatively low.

2, grain size can easy, be quickly reduced, by brilliant pre-treatment step the longest after arranging fusing, simultaneously to long brilliant process In heating-up temperature be defined, and to cooling gas flow and top heater and the heating of four described side heater Power is adjusted, it is achieved high temperature length is brilliant, and completes to put forward under the condition of high temperature cage process accordingly, can be effectively improved polycrystalline silicon ingot casting effect Rate.

Further, during long crystalline substance, the heating-up temperature of polycrystalline silicon ingot or purifying furnace remains unchanged, and is in about 1440 DEG C, so Making crucible internal upper part be in molten condition all the time, top liquid level is steady, make long brilliant process can quickly, high-quality carry out, long brilliant rank Section controls simplicity.Further, the heat-insulation cage hoisting depth of polycrystalline silicon ingot or purifying furnace is 8cm/h～12cm/h, carries width big.Thus, can have Effect improves long brilliant efficiency.

3, to long brilliant pre-treatment step is reasonable in design and realization is easy, using effect is good after fusing, after having melted, first will The heating-up temperature of polycrystalline silicon ingot or purifying furnace is down to T4 by T3 and is incubated 15min～25min, after being cooled to T4, owing to T4 is less than silicon Melting temperature, makes the silicon liquid energy spontaneous nucleation after fusing, i.e. automatically forms nucleus, controls simplicity；Afterwards, then by polycrystalline silicon ingot casting The heating-up temperature of stove is risen to T5 by T4 and is incubated 8min～15min, makes formed nucleus stable, and starts growth.Thus, step To the transition stage that long brilliant pre-treatment is linking fusion process and long brilliant process after fusing in rapid five so that fusion process to The transition of long brilliant process is more steady and easily controllable

4, the hexahedro heater simple in construction that used, reasonable in design and input cost is relatively low, is laid in polysilicon casting In ingot stove, and it is provided with the temperature-detecting device that the heating-up temperature to hexahedro heater detects in real time, temperature control process Easily controllable and temperature detection result intuitive display, can be to the heating temperature of top heater, bottom heater and side heater Degree detects the most in real time.

5, the hexahedro heater used is installed and is laid simplicity, and to existing polycrystalline silicon ingot or purifying furnace inner heating device Change less, only need to set up bottom heater below crucible, and bottom heater is fixed on and is supported in crucible bottom DS block on, fixing simplicity.

6, in the hexahedro heater used, top heater, bottom heater and side heater use the most independent Power supply, top heater, bottom heater and side heater can individually control and the heating power of three can separate Individually be controlled, now control mode have the advantage that first, more energy-conservation, as sidepiece can be reduced in crystal growing stage The heat time heating time of heater, thus reach to reduce the purpose of h eating power, can effectively reduce unit interval inner cooling water band simultaneously The heat walked, thus indirectly decrease the load of power refrigeration equipment；The second, thermal field can be better controled over, owing to top adds Hot device, bottom heater and side heater can individually control, and simplicity can realize top heater, bottom heater and side The purpose of portion's heater separately heating, it is thus possible to reach effectively to control the purpose of thermal field；3rd, crystal growing process is had The biggest improvement result, is conducive to being internally formed vertical gradient thermal field evenly at polycrystalline silicon ingot or purifying furnace, thus preferably controls The long brilliant speed of system so that long crystal boundary face is more mild, thus reduces the unfavorable factor such as shade, red sector, and heats is more preferably；The Four, can effectively alleviate the load of carrying on main line, effectively reduce the electric current superposition amount on main line, thus reduce line load Amount, has certain protective effect for bus and switchgear house；5th, the service life of internal thermal field can be extended, as on long brilliant rank After section reduces the heat time heating time of side heater, can effectively reduce the side heater thermo-contact time to adjacent warming plate, from And extend the service life of internal insulation plate and thermal field.

7, the hexahedro heater used uses easy and simple to handle, is added hexahedro heater by temperature-detecting device Hot temperature detects and by detected temperature information synchronous driving in real time to main controller, then by main controller to being laid in polycrystalline Hexahedro heater in silicon ingot furnace is controlled.

8, the hexahedro heater using effect used is good and practical value high, changes existing polycrystalline silicon ingot or purifying furnace and adopts Carry out thermal-radiating mode of heating from top to down with five heating arrangements, after setting up bottom heater below crucible, form one Individual from upper and lower, left and right, front and rear six direction hexahedro heating arrangement that silicon material in crucible is heated, and control letter Just, temperature control process is easily controllable, can not only improve melting efficiency, and can be effectively improved the heating of crucible bottom during melt Speed, beneficially crucible bottom gas are discharged, it is thus possible to effectively reduce the bottom oxygen content of ingot casting finished product, can significantly improve ingot casting The yield rate of finished product and quality.Thus, use hexahedro heater that silicon material in crucible is heated, existing polysilicon can be solved The melting efficiency that ingot furnace is used five heating arrangements to exist is relatively low, crucible bottom gas is difficult to bottom eliminating, ingot casting finished product The problem such as oxygen content is higher.

9, during melt, the heating power of top heater, bottom heater and side heater controls easy and realizes Convenient, in fusion process, after the silicon material in crucible all melts, the heating-up temperature controlling polycrystalline silicon ingot or purifying furnace keeps constant, And the time dependent curve of heating power (i.e. power curve) of polycrystalline silicon ingot or purifying furnace is observed；Wherein, in treating crucible Silicon material all melt after, the power curve of polycrystalline silicon ingot or purifying furnace begins to decline, treat polycrystalline silicon ingot or purifying furnace power curve decline And after walking flat 20min～40min, melt process completes, carry out crystal growing stage afterwards.In actual mechanical process, by observation merit Rate curve just can accurately determine the time point that melt process completes, and is i.e. switched to the switching time of crystal growing stage by the melting stage Point.Practical operation is easy, and realizes conveniently, and energy accurate assurance is switched to the switching time of crystal growing stage by the melting stage.The most just Being to say, the present invention stablizes ingot casting melt curve by extending the melt time, cuts after power curve walks flat 20min～40min again Enter crystal growing stage, thus can accurately be melted to the switching time of crystal growing stage, stopped due to melt deficiency of time or molten simultaneously Polycrystalline silicon ingot casting Quality Down that material overlong time causes, the problem such as cost increase.Further, use the present invention to polycrystalline silicon ingot casting During after melt carries out accurate assurance to long brilliant switching time, can ensure that long brilliant quality and be finally made turning of cell piece Change efficiency, it is to avoid because of can not accurate assurance by the melting stage be switched to that the switching time of crystal growing stage causes accordingly due to melt Deficiency of time or melt overlong time and the problem of produced polycrystalline silicon ingot casting Quality Down that causes.

10, fusion process is divided into intensification for the first time, second time to rise gentle subsequent melting three key steps, and mode of heating sets Rationally, heating power is separately individually controlled meter, and not only control simplicity and heats more preferably, can be effectively improved melt process The rate of heat addition of middle crucible bottom, beneficially crucible bottom gas are discharged, it is thus possible to the bottom oxygen effectively reducing ingot casting finished product contains Amount, can significantly improve yield rate and the quality of ingot casting finished product；Meanwhile, can be to melt during polycrystalline silicon ingot casting to long brilliant switching Opportunity carries out accurate assurance, can be effectively improved crystal growth quality, reduces viscous crucible rate, improves the conversion efficiency of solar battery sheet, energy It is effectively improved yield rate.

Further, warm uses hexahedro heating, and fusion process all uses roofing to heat, and main reason is that and prevents silicon Become bottom material after liquid with coating reaction, cause the phenomenons such as viscous pot, crystalline substance split.

11, the annealing time during polycrystalline silicon ingot casting can effectively be reduced, with the annealing during existing polycrystalline silicon ingot casting Technique is compared, and each time annealing temperature is the most relatively low, and it is shorter to make annealing treatment the time, can be effectively improved polycrystalline silicon ingot casting effect Rate.

12, annealing effect is good, can be effectively improved the yield rate of polycrystalline silicon ingot casting finished product, and, due to polycrystalline silicon ingot casting mistake Journey is carried out under vacuum conditions, and annealing process is typically all carried out under lower pressure environment, and under lower pressure environment, the fusing point fall of silicon Low, the softening point of corresponding silicon also reduces, but in existing annealing process, still designs according to fusing point and the softening point of silicon under atmospheric pressure state Annealing temperature, causes actual annealing temperature higher (under normal circumstances, the first annealing temperature is 1370 DEG C～1390 DEG C), and impact is moved back Fire effect.And in the present invention, it is contemplated that under lower pressure environment, fusing point and the softening point of silicon all reduce, and the first annealing temperature is designed as 1250 DEG C～1280 DEG C, annealing temperature is reasonable in design, and can effectively save annealing time.Meanwhile, annealing temperature sets for the second time Being calculated as 900 DEG C～950 DEG C, under this temperature conditions, silica undergoes phase transition, and silicon is prone to oxygen and reacts and generate silicon dioxide Deng, can effectively discharge silicon crystal lattice stress during undergoing phase transition, thus reach the purpose of process annealing release silicon crystal lattice stress, with Time can effectively reduce annealing time.

13, annealing process is reasonable in design and using effect good, and annealing temperature is reasonable in design, can be effectively improved polycrystalline silicon ingot casting Stress state in finished product, and vertical gradient thermal field evenly can be formed, for larger-size ingot casting, annealing During heterogeneity phantom uniform, annealing effect more preferably, can be prevented effectively from the annealing caused because of temperature heating-up temperature skewness Effect is poor, affect the problems such as polycrystalline silicon ingot casting end product quality.

14, the coating material used is by organic cementing agent, deionized water and boron nitride, and cost is relatively low and preparation is easy.

15, the coating material used, using boron nitride as primary raw material, can effectively increase crucible bottom heat-conducting effect, and Can reduce crucible bottom oxygen content, Simultaneous Stabilization is good, is not easily formed Hard Inclusion during ingot casting, and ingot casting finished product can be effectively ensured Quality.

With use Si during existing crucible spraying₃N₄Material is compared as sprayed on material, at the bottom of the used crucible of the present invention Portion's coating result is the best, because of Si₃N₄The features such as the heat conductivility of material itself is poor, unstability, easy shape during making ingot casting Become the oxygen content bottom Hard Inclusion, and ingot casting finished product higher, the quality of product is had a great impact；Meanwhile, Si₃N₄Material Although silicon liquid and crucible reaction can be effectively isolated, but Si₃N₄Form red sector after reacting with silicon liquid, be easily introduced impurity Si₃N₄ And form Hard Inclusion, the quality of ingot casting finished product is affected the biggest；And the present invention used crucible bottom coating can be effectively ensured casting The quality of ingot finished product.

16, the coating material used can effectively reduce the cost of polycrystalline silicon ingot casting, owing to boron is originally as polycrystalline silicon ingot casting A kind of adulterant of Shi Suoyong, but the cost of pure boron is at a relatively high；And make after using the coating material coating disclosed in the present invention During standby polysilicon ingot crucible base coat, the doping of pure boron can be reduced, even avoid adding pure boron, it is thus possible to effectively Reduce polycrystalline silicon ingot casting cost.

17, the painting method used is reasonable in design and realization is easy, using effect is good, can be easy, quickly at the bottom of crucible Portion makes one layer of base coat, and the base coat quality made is good, and coating procedure is easily controllable.Meanwhile, used Drying structure is reasonable in design and cost is relatively low, using effect goods, and energy is easy, be rapidly completed the drying course of crucible bottom coating, And heats is good, crucible bottom uniform coating thickness and quality that machine-shaping can be effectively ensured are good.

18, practical, it is simple to batch production, use hexahedro heater to heat, can effectively reduce crucible bottom Oxygen content, and can effectively reduce the Hard Inclusion of ingot casting finished product, improve the quality of ingot casting finished product；Meanwhile, by annealing process is entered Row improves, and anneals at twice, for the first time annealing according to the softening point reasonable set annealing temperature of silicon under low-pressure state, second Secondary carry out annealing under cryogenic and make silicon crystal lattice stress effectively be discharged, improve polycrystalline silicon ingot casting end product quality.It addition, it is logical Cross and coat one layer of base coat with boron nitride as primary raw material in crucible bottom, can effectively reduce crucible bottom oxygen content, and Can effectively reduce the Hard Inclusion of ingot casting finished product, the quality of ingot casting finished product can be improved further

Thus, the present invention mainly improves silicon casting in terms of hexahedro heater, crucible bottom coating, improvement annealing process etc. Ingot end product quality, simultaneously by brilliant pre-treatment step the longest after setting up fusing, and is adjusted crystal growing technology, can effectively reduce Grain size, and improve the yield rate of silicon ingot casting finished product accordingly.

In sum, present invention process step is simple, reasonable in design and realization is easy, using effect is good, uses hexahedro adding Thermal heats, and simultaneously by brilliant pre-treatment step the longest after setting up fusing, and is adjusted crystal growing technology, can be effective Reduce grain size, improve the quality of ingot casting finished product.

Below by drawings and Examples, technical scheme is described in further detail.

Accompanying drawing explanation

Fig. 1 is the method flow block diagram of the present invention.

Fig. 2 is the structural representation of the crucible of band base coat of the present invention.

Fig. 3 is the structural representation of baking oven of the present invention.

Fig. 4 is the method flow block diagram that the present invention coats boron nitride coating material bottom polysilicon ingot crucible.

Fig. 5 is used the use view of hexahedro heater by the present invention.

Fig. 6 is used the schematic block circuit diagram of hexahedro heater by the present invention.

Fig. 7 is temperature and the power using the present invention top heater and side heater when melting.

Description of reference numerals:

1 crucible；2 top heater；2-1 top firing power supply；

3 bottom heaters；3-1 bottom-heated power supply；4 side heater；

4-1 sidepiece heating power supply；5 DS blocks；6 heating power adjusting meanss；

7 crucible guard boards；8 main controllers；9 polycrystalline silicon ingot or purifying furnaces；

10 top firing temperature detecting units；

11 sidepiece heating-up temperature detector units；

12 bottom-heated temperature detecting units；13 heat-preservation cylinders；

14 pressure pins；15 horizontal heaters；16 vertical heaters；

17 graphite cushion blocks.

Detailed description of the invention

A kind of polycrystalline silicon casting ingot process as shown in Figure 1, comprises the following steps:

Step one, auxiliary heater are installed: install auxiliary heater in polycrystalline silicon ingot or purifying furnace 9；

Described auxiliary heater is to be laid in the bottom heater 3 below crucible 1, described crucible 1 be cube crucible and It is level lay, described bottom heater 3, be laid in the top heater 2 above crucible 1 and four be laid in crucible respectively The side heater 4 of four side-wall outer side of 1 forms hexahedro heater；Described top heater 2 and bottom heater 3 all in Level is laid, four described side heater 4 all in vertically to laying；Described top heater 2, bottom heater 3 and four Described side heater 4 is all laid in polycrystalline silicon ingot or purifying furnace 9；

Step 2, charging: in crucible 1, load silicon material, and the crucible 1 of built-in silicon material is loaded in polycrystalline silicon ingot or purifying furnace 9；

Step 3, preheating: top heater 2, bottom heater 3 and four described side heater 4 are all opened, and adopts With polycrystalline silicon ingot or purifying furnace 9, the silicon material being loaded in crucible 1 is preheated, and the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is progressively carried Rise to T1；Preheating time is 5h, wherein T1=1200 DEG C；

Step 4, fusing, process is as follows:

Step 401, the hexahedro heat fusing that adds: use polycrystalline silicon ingot or purifying furnace 9 that the silicon material being loaded in crucible 1 is melted, molten Change temperature to be stepped up to T2 by T1；Wherein T2=1380 DEG C；In this step, described top heater 2, bottom heater 3 and Four described side heater 4 are in opening；

Step 402, five faces add heat fusing: the silicon material using polycrystalline silicon ingot or purifying furnace 9 to continue being loaded in crucible 1 melts Changing, fusion temperature is stepped up to T3 by T2；Wherein T3=1550 DEG C；In this step, described in described top heater 2 and four Side heater 4 is in opening, and described bottom heater 3 is closed；

Step 403, subsequent melting: after the silicon material in crucible 1 all melts, by the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 Controlling at T3, the heating power of the most described top heater 2 and four described side heater 4 all begins to decline, and treats described After the heating power of top heater 2 and four described side heater 4 all stops decline and persistent period t, melt process is complete Become；Wherein t=30min；

To long brilliant pre-treatment after step 5, fusing, process is as follows:

Step 501, cooling: the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is down to T4 by T3, and is incubated 20min；Wherein T4= 1415℃；

Step 502, intensification: the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is risen to T5 by T4, and is incubated 10min；Wherein T5= 1440℃；

Step 6, long crystalline substance: the heating and temperature control of polycrystalline silicon ingot or purifying furnace 9 at T5 and is carried out directional solidification, until completing Long brilliant process；

In the present embodiment, described in step 5, step 6 and step 7, bottom heater 3 is in closed mode.

During actually used, can according to specific needs the size of T1, T2, T3, T4 and T5 be adjusted accordingly.Its In, T3 is unmelted polycrystalline silicon temperature.

In the present embodiment, during carrying out long crystalline substance in step 6, the heat-insulation cage hoisting depth of described polycrystalline silicon ingot or purifying furnace 9 is 8cm/h～12cm/h.

Further, during step 6 carries out long crystalline substance, it is positioned at the top above crucible 1 in described polycrystalline silicon ingot or purifying furnace 9 and adds The heating power of hot device 2 is 80kW～95kW, the side heater 4 of four four side-wall outer side being laid in crucible 1 respectively Heating power is 30kW～50kW.

During actually used, the heating power of top heater 2 is adjusted accordingly in the range of 80kW～95kW, And the heating power of four described side heater 4 is adjusted accordingly in the range of 30kW～50kW.

In the present embodiment, in polycrystalline silicon ingot or purifying furnace 9 described in step one, it is provided with gas chiller；Step 5 is carried out During long crystalline substance, by increasing the cooling gas flow of described gas chiller by the heating-up temperature control of polycrystalline silicon ingot or purifying furnace 9 Make to T5.Further, by increasing the cooling gas flow of described gas chiller, by the cooling gas of described gas chiller Body volumetric concentration is adjusted in the range of 60ppm～80ppm.

Time actually used, by the heating power of the described side heater 4 of top heater 2 and four, and adjust described The cooling gas flow of gas chiller, by the heating and temperature control of polycrystalline silicon ingot or purifying furnace 9 to T5.

Time actually used, the present invention is by brilliant pre-treatment step the longest after the fusing described in setting steps five, the most right In step 6, the heating-up temperature during long crystalline substance is defined, and to cooling down gas flow and top heater 2 and four institutes The heating power stating side heater 4 is adjusted, it is achieved high temperature length is brilliant, and completes to carry under the condition of high temperature cage process, energy accordingly It is effectively improved polycrystalline silicon ingot casting efficiency.

Further, during long crystalline substance, the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 remains unchanged, and is in 1440 DEG C, so makes earthenware Crucible 1 internal upper part is in molten condition all the time, and top liquid level is steady, make long brilliant process can quickly, high-quality carry out, crystal growing stage control System simplicity.Further, the heat-insulation cage hoisting depth of described polycrystalline silicon ingot or purifying furnace 9 is 8cm/h～12cm/h, carries width big.Thus, can have Effect improves long brilliant efficiency.

Wherein, after having melted, first the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 it is down to T4 by T3 and is incubated 20min, cooling To T4, owing to T4 is less than the melting temperature of silicon, make the silicon liquid energy spontaneous nucleation after fusing, i.e. automatically form nucleus, control letter Just；Afterwards, then the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 risen to T5 by T4 and be incubated 10min, making formed nucleus stable, And start growth.Thus, to the transition that long brilliant pre-treatment is linking fusion process and long brilliant process after fusing in step 5 Stage so that fusion process is more steady and easily controllable to the transition of long brilliant process,

Time actually used, to long brilliant pretreatment process neutralization procedure after fusing in step 4 in fusion process, in step 5 In six during long crystalline substance, in polycrystalline silicon ingot or purifying furnace 9, all it is filled with noble gas and polycrystalline silicon ingot or purifying furnace 9 internal gas pressure is maintained at Q2, wherein Q2=550mbar～650mbar.In the present embodiment, Q2=600mbar.

Actual when melting, can according to specific needs the value size of Q2 and t be adjusted accordingly.

At present, polycrystalline silicon ingot casting method mainly has half casting process and fine melt ingot casting method two kinds, and half casting process is also referred to as There is seed crystal ingot casting polycrystalline silicon process, refer to use grade silicon material to carry out epitaxial growth as nucleating center, cast low defect Gao Pin The polycrystalline silicon ingot casting of matter；Fine melt ingot casting method is also referred to as without seed crystal ingot casting polycrystalline silicon process or without seed crystal efficient polycrystalline silicon technology, refers to Non-silicon material is used to prepare shaggy heterogeneous forming core layer in crucible bottom, during by the roughness of control forming core layer with forming core Degree of supercooling obtains bigger nucleation rate, casts low defect high-quality polycrystalline silicon ingot casting.At present, polycrystalline silicon ingot casting method is cast with fine melt Ingot method is main.Herein, the polycrystalline silicon ingot casting method used is conventional polycrystalline silicon ingot casting method, specially fine melt polysilicon casting Ingot method.

Thus, step 2 carried out feed, step 3 carried out preheat, step 4 carries out melting and carrying out in step 7 When annealing and cooling, the method used is the conventional method that fine melt polycrystalline silicon ingot casting method uses.

In the present embodiment, described crucible 1 is cube crucible.

In the present embodiment, when annealing in step 7 and cool down, process is as follows:

Step 701, for the first time annealing: through 1h, the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is down to T6, and is incubated 2.5h；Its In, T6=1260 DEG C；

Step 702, second time annealing: through 1h, the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is down to T7 by T6, and is incubated 2.5h；T7=920 DEG C；

In the present embodiment, step 701 is carried out first time annealing process neutralization procedure 702 carries out second time annealing process In, in described polycrystalline silicon ingot or purifying furnace 9, all it is filled with noble gas and the air pressure in polycrystalline silicon ingot or purifying furnace 9 is maintained at Q1, wherein Q1=200Pa.

Further, described noble gas is argon.

Actual add man-hour, can according to specific needs the value size of T6, T7 and Q1 be adjusted accordingly respectively.

In the present embodiment, when step 703 cools to processed polycrystalline silicon ingot casting with the furnace room temperature, according to 100 DEG C/h's Rate of temperature fall cools down.

Actual when cooling down, can according to specific needs rate of temperature fall be adjusted accordingly.

Actual when carrying out polycrystalline silicon ingot casting, carry out the most under vacuum conditions, and annealing process is general all in low pressure Carry out under environment.Owing to, under lower pressure environment, the fusing point of silicon reduces, and the softening point of corresponding silicon also reduces.And in existing annealing process, Still design annealing temperature according to fusing point and the softening point of silicon under atmospheric pressure state, cause actual annealing temperature higher (under normal circumstances, First annealing temperature is 1370 DEG C～1390 DEG C), affect annealing effect.And in the present invention, it is contemplated that under lower pressure environment, silicon is molten Point and softening point all reduce, and the first annealing temperature is designed as 1250 DEG C～1280 DEG C, and annealing temperature is reasonable in design, and can be effective Save annealing time.Meanwhile, annealing temperature is designed as 900 DEG C～950 DEG C for the second time, under this temperature conditions, and silica generation phase Becoming, silicon is prone to oxygen and reacts and generate silicon dioxide etc., can effectively discharge silicon crystal lattice stress during undergoing phase transition, and improves casting Ingot end product quality, thus reach the purpose of process annealing release silicon crystal lattice stress, can effectively reduce annealing time simultaneously.

Compared with conventional annealing process, lehr attendant's artistic skill disclosed by the invention is used to make the finished product of polycrystalline silicon ingot casting finished product Rate improves more than 5%.

In the present embodiment, before charging is carried out in step 2, also needing to carry out crucible bottom coating and prepare, process is as follows:

Step 101, coating spraying liquid prepare: by organic cementing agent, deionized water and boron nitride by 1: 2～2.5: 0.8～ The mass ratio of 1.2 uniformly mixes, and obtains coating spraying liquid；

Step 102, spraying: use spraying equipment by the even application of coating spraying liquid described in step 101 to crucible 1 On bottom surface, portion, 1m in described crucible 1 inner bottom surface²In region, in the described coating spraying liquid of spraying, the quality of contained boron nitride is 100g～150g；

Described crucible 1 uses silica crucible for polycrystalline silicon ingot or purifying furnace 9；

Step 103, drying: crucible 1 described in step 102 is placed horizontally in drying plant, and uses described drying Equipment and under 90 DEG C of temperature conditionss, the described coating spraying liquid being sprayed in crucible 1 inner bottom surface being dried, it is thus achieved that the end Portion's coating 2, refers to Fig. 2；

When step 2 feeds, in the crucible 1 of band base coat 2 in load silicon material, and by the earthenware of built-in silicon material Crucible 1 loads in polycrystalline silicon ingot or purifying furnace 9.

Wherein, the actual crucible bottom coating that carries out is when preparing, and the painting method of crucible bottom coating 2 refers to Fig. 4.

Time actually used, can according to specific needs, to cementing agent organic in coating spraying liquid described in step 101, go from The mass ratio of sub-water and boron nitride adjusts accordingly.

In the present embodiment, described organic cementing agent is phenolic aldehyde-neoprene adhesive.

Wherein, the kind of phenolic aldehyde-neoprene adhesive is more, mainly include anchor 801 seccotine, hundred glue, JX- 15-1 glue, FN-303 glue, CX-401 glue, XY-401 glue, CH-406 glue etc..Above-mentioned phenolic aldehyde-neoprene adhesive is commercially available Commodity, can directly obtain.

Time actually used, described organic cementing agent can also be organic silicon adhesive, epoxy adhesive, Instant adhesive, Acrylic acid adhesive, polyvinyl alcohol adhesive, Polyvinyl acetate adhesive, AE SGA, butvar adhesive are viscous Agent or glass cement.

Wherein, organic silicon adhesive (also referred to as organosilicon adhesive) point one pack system, bi-component, room temperature vulcanization and heating sulfur Change etc. multiple, the major product trade mark of room temperature vulcanized has 703,704, FS-203, GD-400 etc..According to solidification temperature, organic Silica gel stick can be divided into hot setting, low-temperature setting and cold curing three class.Organic silicon adhesive of the present invention is low Temperature curing organic silicon adhesive.

Epoxy adhesive is Vinylidene Chloride epoxy adhesive or furan modified epoxy adhesive.

Instant adhesive is also referred to as instant glue, and conventional is ethyl α-cyanoacrylate, product designation 502 glue；Medical Alpha-cyanoacrylate butyl ester, product designation 504 glue.

Acrylic acid adhesive, commercially available kind has SA-200, AB glue, J-39, J-50, SGA-404, SGA etc..

In the present embodiment, described boron nitride is boron nitride powder.

In the present embodiment, described boron nitride is hexagonal boron nitride.

In the present embodiment, spraying equipment described in step 102 is liquid spray gun.

Time actually used, spraying equipment described in step 102 can also be other type of liquid spraying equipment.

In the present embodiment, drying plant described in step 103 is baking oven.

As it is shown on figure 3, crucible 1 described in step 102 is cube crucible；Crucible 1 described in step 103 and described baking oven All lay in level；

Described baking oven includes casing, be laid in the horizontal heater 15 bottom crucible 1 and four be laid in crucible 1 respectively The vertical heater 16 of four side-wall outer side, four described vertical heaters 16 are respectively positioned on above horizontal heater 15, described water The graphite cushion block 17 placed for crucible 1 it is provided with on flat heater 15.

In the present embodiment, described horizontal heater 15 and four described vertical heaters 16 are resistance heater.

In the present embodiment, when step 102 sprays, 1m in described crucible 1 inner bottom surface²In region, spraying is described In coating spraying liquid, the quality of contained boron nitride is 150g.

Preferably, when step 102 sprays, 1m in described crucible 1 inner bottom surface²The described coating of spraying in region In spray coating liquor, the quality of contained boron nitride is 100g～150g.

During actually used, can according to specific needs, to 1m in crucible 1 inner bottom surface²The described painting of spraying in region In layer spray coating liquor, the quality of contained boron nitride adjusts accordingly.

In the present embodiment, when step 103 is dried, first use described drying plant that crucible 1 is heated to 90 DEG C, then Carry out being incubated till the described coating spraying liquid being sprayed in crucible 1 inner bottom surface is dried.

Actual when drying, can adjust accordingly drying temperature according to specific needs.

It is good etc. that boron nitride owing to containing in described base coat has good heat conductivity, good stability, resistance to elevated temperatures Advantage, can effectively strengthen the heat-conducting effect bottom crucible 1, can be effectively improved melting efficiency, and being difficult to of crucible 1 bottom gas Get rid of, can effectively reduce the oxygen content bottom crucible 1, make the oxygen content bottom ingot casting finished product reduce.Meanwhile, boron nitride and oxygen exist Under high temperature, reaction generates B₂O₃And nitrogen dioxide gas (NO₂) etc., the oxygen content bottom crucible 1 can be reduced further, and raw The B become₂O₃Compare Si₃N₄Stable, it is not easily formed Hard Inclusion during ingot casting, thus can effectively reduce the Hard Inclusion of ingot casting finished product, with Time can be effectively improved the minority carrier life time of ingot casting finished product, the quality of ingot casting finished product can be effectively improved.

At present, polycrystalline silicon ingot casting method mainly has half casting process and fine melt ingot casting method two kinds, and half casting process is also referred to as There is seed crystal ingot casting polycrystalline silicon process, refer to use grade silicon material to carry out epitaxial growth as nucleating center, cast low defect Gao Pin The polycrystalline silicon ingot casting of matter；Fine melt ingot casting method is also referred to as without seed crystal ingot casting polycrystalline silicon process or without seed crystal efficient polycrystalline silicon technology, refers to Non-silicon material is used to prepare shaggy heterogeneous forming core layer in crucible bottom, during by the roughness of control forming core layer with forming core Degree of supercooling obtains bigger nucleation rate, casts low defect high-quality polycrystalline silicon ingot casting.At present, polycrystalline silicon ingot casting method is cast with fine melt Ingot method is main.

In the present embodiment, when step 2 feeds, feed according to the loading method of conventional fine melt ingot casting method.

In the present embodiment, polycrystalline silicon ingot or purifying furnace 9 described in step one is G5 type ingot furnace.Further, described polycrystalline silicon ingot casting Stove 9 is specially the G5 type ingot furnace that Zhejiang Jingsheng Electrical and Mechanical Co., Ltd. produces.Described crucible 1 be silica crucible and its be G5 Crucible, and the polycrystalline silicon ingot casting produced is G5 ingot.

Time actually used, the charge of described silica crucible is about 600kg.

In the present embodiment, the charge of described silica crucible is 560kg.During actually used, can be according to concrete need Want, the charge of described silica crucible is adjusted accordingly.

In conjunction with Fig. 6, in the present embodiment, when step one carries out auxiliary heater installation, also need top heater 2, the end Portion's heater 3 and four described side heater 4 are all connected with heating power adjusting means 6；

In step 3 in warm, use heating power adjusting means 6 to top heater 2, bottom heater 3 and four The heating power of individual described side heater 4 synchronizes to be stepped up.

In the present embodiment, hexahedro heater described in step one also includes main controller 8 and temperature-detecting device, described temperature Top firing temperature detecting unit 10 that degree detection device includes detecting the heating-up temperature of top heater 2 in real time, right Sidepiece heating-up temperature detector unit 11 that the heating-up temperature of side heater 4 detects in real time and adding bottom heater 3 The bottom-heated temperature detecting unit 12 that hot temperature detects in real time, described top firing temperature detecting unit 10, sidepiece add Hot temperature detecting unit 11 and bottom-heated temperature detecting unit 12 are all connected with main controller 8；Set in described polycrystalline silicon ingot or purifying furnace 9 Being equipped with heat-preservation cylinder 13, described hexahedro heater is positioned at heat-preservation cylinder 13.Meanwhile, described main controller 8 arranges list with parameter respectively Unit 14 and display unit 15 connect.

In the present embodiment, described bottom heater 3 is fixed on the DS block 5 being supported in bottom crucible 1, described bottom-heated Distance between bottom device 3 top and DS block 5 is 0.5cm～3m.

During actual installation, can according to specific needs the distance between bottom bottom heater 3 top and DS block 5 be carried out Corresponding regulation.

Wherein, DS block 5 is graphite block, and the heat conductivity of described graphite block is the strongest.Described DS block 5 also referred to as directional solidification block or DS-BLOCK。

In the present embodiment, described heating power adjusting means 6 is connected with main controller 8.

Described top firing power supply 2-1, sidepiece heating power supply 4-1 and bottom-heated power supply 3-1 are power adjustable economize on electricity Source, and top heater 2, bottom heater 3 be respectively adopted three different power supplys (i.e. with four described side heater 4 Described top firing power supply, described sidepiece heating power supply and described bottom-heated power supply), top heater 2 can be realized, bottom adds Hot device 3 and the independent control of side heater 4, use easy and simple to handle and using effect good.

In the present embodiment, described heating power adjusting means 6 includes three heating power regulation equipment, adds described in three Thermal power regulation equipment is respectively the first heating power regulation equipment, right being adjusted the heating power of top heater 2 The second heating power that the heating power of bottom heater 3 is adjusted regulates equipment and to four described side heater 4 Heating power carries out the 3rd heating power regulation equipment of adjusted in concert.

Time actually used, three described heating power regulation equipment can also share a described heating power regulation and set Standby, only need the purpose that can reach three described power supplys are respectively controlled.

In the present embodiment, described bottom heater 3 is positioned at the underface of crucible 1.

In the present embodiment, described top heater 2, side heater 4 and bottom heater 3 are resistance heater.

Wherein, described top heater 2 and side heater 4 are the existing heating that existing polycrystalline silicon ingot or purifying furnace uses Device, described top heater 2 and the structure of four described side heater 4 and installation position are existing polycrystalline silicon ingot or purifying furnace phase With.Each described side heater 4 all sidewalls with crucible 1 on its inside are parallel laying.

In the present embodiment, the resistance wire material of described bottom heater 3 is the alloy cpds such as Ni, Cr, Mn.

In the present embodiment, four side-wall outer side of described crucible 1 are provided with crucible guard boards 7, described side heater 4 Outside crucible guard boards 7；Described crucible guard boards 7 is in vertically to the graphite cake laid.

Meanwhile, it is additionally provided with pressure pin 14 below described crucible 1.

During actual installation, described top heater 2 and four described side heater 4 are all lifted on polycrystalline by lifting part On the top cover of silicon ingot furnace 9.

In the present embodiment, in step 3 in warm neutralization procedure 401 in hexahedro heating fusion process, synchronization institute The heating power stating the described side heater 4 of top heater 2, bottom heater 3 and four is the most identical；In step 402 five Heating fusion process neutralization procedure 403 in subsequent melting during, top heater 2 described in synchronization and four described sidepieces The heating power of heater 4 is the most identical.

In step 3 in warm neutralization procedure 401 in hexahedro heating fusion process, top firing described in synchronization Device 2, bottom heater 3 are the most identical with the heating-up temperature of four described side heater 4；In step 402, five faces add heat fusing mistake In journey neutralization procedure 403 subsequent melting during, top heater 2 described in synchronization and four described side heater 4 Heating-up temperature is the most identical.

Further, heating-up temperature or the fusion temperature of described polycrystalline silicon ingot or purifying furnace 9 is top heater 2 or side heater 4 Heating-up temperature.

In the present embodiment, in step 3 in warm, by top heater 2, bottom heater 3 and four described sidepieces The heating power of heater 4 synchronizes to be stepped up, and top heater 2, bottom heater 3 and four described sidepieces is added The heating power of hot device 4 is all stepped up to P1, wherein P1=75kW.

In the present embodiment, in step 3, preheating time is 5h；In warm, by the heating power of polycrystalline silicon ingot or purifying furnace 9 Step up to P1 with the rate of rise of 10kW/h～15kW/h；

The heating power of described polycrystalline silicon ingot or purifying furnace 9 is top heater 2 or the heating power of side heater 4.

Actual when preheating, can according to specific needs, to the growth speed of heating power in preheating time, warm The value size of rate and T1 and P1 adjusts accordingly.

When step 4 melts, can according to specific needs the value size of T2, T3 and t be carried out respectively accordingly Adjust.

In the present embodiment, in step 401 in hexahedro heating fusion process, described top heater 2, bottom heater 3 and The heating power of four described side heater 4 is P1；

In step 402 in five heating fusion processes, adding of described top heater 2 and four described side heater 4 Thermal power is P1；

In step 403 subsequent melting during, after the silicon material in crucible 1 all melts, described top heater 2 and four The heating power of individual described side heater 4 synchronizes progressively to decline, to top heater 2 or the heating of side heater 4 Changed power situation is observed, and when the heating power of top heater 2 or side heater 4 drops to P2, keeps P2 not Become and after persistent period t, melt process completes；Wherein, P2=35kW.

Actual when melting, according to the difference of charge in crucible 1, the size of P2 is accordingly in the range of 25kW～45kW It is adjusted.

In the present embodiment, in step 4 in fusion process, in polycrystalline silicon ingot or purifying furnace 9, it is filled with noble gas and by polysilicon Ingot furnace 9 internal gas pressure is maintained at Q2, wherein Q2=600mbar.

Actual when melting, can according to specific needs the value size of Q2 be adjusted accordingly.

In the present embodiment, after the silicon material in crucible 1 all melts, the heating and temperature control of polycrystalline silicon ingot or purifying furnace 9 is existed T3, and the time dependent curve of heating power (i.e. power curve) of polycrystalline silicon ingot or purifying furnace 9 is observed, refer to Fig. 7.Figure In 7, fine line is the time dependent curve of heating power of polycrystalline silicon ingot or purifying furnace 9, and needing solid line is adding of polycrystalline silicon ingot or purifying furnace 9 The time dependent curve of hot temperature, vertical line is alarming line when all melting of the silicon material in crucible 1.As seen from Figure 7, treat After silicon material in crucible 1 all melts, the power curve of described polycrystalline silicon ingot or purifying furnace 9 begins to decline, and treats polycrystalline silicon ingot or purifying furnace 9 After power curve declines and walks flat 30min, melt process completes, and enters crystal growing stage afterwards；A point in i.e. Fig. 7 is melt mistake The time point that journey completes.

In actual mechanical process, just can accurately be determined the time point that melt process completes by observed power curve, i.e. by Melting stage is switched to some switching time of crystal growing stage.Practical operation is easy, and realizes conveniently, and energy accurate assurance is by melting rank Section is switched to the switching time of crystal growing stage.

In the present embodiment, when melting in step 4, process is as follows:

1st step, insulation: by the heating and temperature control of polycrystalline silicon ingot or purifying furnace 9 at T1, and be incubated 0.5h；

2nd step to the 5th step, heat up and pressurize: by first to rear point of four step by the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 by T1 by Gradually being promoted to T8, the heating-up time is 0.5h (total time of the i.e. the 2nd step to the 5th step is 0.5h)；Temperature-rise period is cast to polysilicon It is filled with noble gas in ingot stove 9 and polycrystalline silicon ingot or purifying furnace 9 internal gas pressure is stepped up to Q2；Wherein, T8=1250 DEG C；

6th step, for the first time intensification and pressurize: the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is gradually promoted to by T6 T9 and liter The temperature time is 4h, and in temperature-rise period, polycrystalline silicon ingot or purifying furnace 9 internal gas pressure is maintained at Q2；Wherein, T9=1450 DEG C；

7th step: second time heats up and pressurize: the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is gradually promoted to T10 and liter by T7 The temperature time is 4h, and in temperature-rise period, polycrystalline silicon ingot or purifying furnace 9 internal gas pressure is maintained at Q1；Wherein, T10=1500 DEG C；

8th step, third time heat up and pressurize: the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is gradually promoted to T3 and liter by T10 The temperature time is 4h, and in temperature-rise period, polycrystalline silicon ingot or purifying furnace 9 internal gas pressure is maintained at Q2；

9th step, insulation: by the heating and temperature control of polycrystalline silicon ingot or purifying furnace 9 at T3, and be incubated 4h；In insulating process, described Polycrystalline silicon ingot or purifying furnace 9 internal gas pressure is maintained at Q2；

10th step, persistently insulation: by the heating and temperature control of polycrystalline silicon ingot or purifying furnace 9 at T3, and be incubated 6h, until crucible 1 Interior silicon material all melts；In insulating process, described polycrystalline silicon ingot or purifying furnace 9 internal gas pressure is maintained at Q2.

In the present embodiment, by rear point of four steps by the heating-up temperature of described ingot furnace by T1 the most gradually in the 2nd step to the 5th step When being promoted to T6, each step promotes temperature 5 DEG C～8 DEG C, and each step promotes and is both needed to 5min～10min.

In the present embodiment, the 6th step is carried out heat up for the first time and carry out in pressure maintaining period, in the 7th step second time heat up and Carry out third time in pressure maintaining period, in the 8th step heat up and pressure maintaining period neutralization the 9th step carries out in insulating process, be both needed to many The heating power situation of change of crystal silicon ingot furnace 9 is observed, and guarantees the heating power change of polycrystalline silicon ingot or purifying furnace 9 steadily.

During it is to say, the 6th step to the 9th step melts, it is necessary to make power curve steadily advance, it is impossible to occur more Significantly sags and crests, so can bring increasing of Hard Inclusion.

In the present embodiment, when heating up and pressurize in the 2nd step to the 5th step, process is as follows:

2nd step, the first step promote: by 1200 DEG C, the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is promoted to 1220 DEG C, and heat up Time is 7min.

3rd step, second step promote: by 1220 DEG C, the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is promoted to 1235 DEG C, and heat up Time is 8min.

4th step, the 3rd step promote: by 1235 DEG C, the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is promoted to 1242 DEG C, and heat up Time is 5min.

5th step, the 4th step promote: by 1242 DEG C, the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is promoted to 1250 DEG C, and heat up Time is 5min.

In the present embodiment, the 10th step is treated the silicon material in crucible 1 all melt and described ingot furnace send " fusing complete report Alert " after, need manual intervention, the decline situation of power curve is observed, treat that the power curve of described ingot furnace declines and walks After flat 30min, melt process completes, and manual intervention afterwards will be cut into crystal growing stage the melting stage.

Thus, after in step 6, long crystalline substance terminates, the heating-up temperature of described polycrystalline silicon ingot or purifying furnace is T5；Step 2051 is carried out For the first time during annealing, the heating-up temperature of described polycrystalline silicon ingot or purifying furnace is down to T6 by T5.

In the present embodiment, the surface free from admixture of machine-shaping ingot casting finished product, without viscous crucible phenomenon, bottom ingot casting, oxygen content reduces More than 70%, minority carrier life time ＞ 5.5us (microsecond), Hard Inclusion ratio ＜ 0.5%, yield rate is 80%, and grain size is 8 grades.

Embodiment 2

In the present embodiment, as different from Example 1: organic cementing agent, deionized water and boron nitride are pressed by step 101 The mass ratio of 1: 2: 0.8 uniformly mixes, and obtains coating spraying liquid；Described organic cementing agent is organic silicon adhesive；In step 102 When spraying, 1m in described crucible 1 inner bottom surface²The quality of contained boron nitride in the described coating spraying liquid of spraying in region For 100g；When step 103 is dried, use described drying plant and to being sprayed in crucible 1 under 80 DEG C of temperature conditionss Described coating spraying liquid on bottom surface, portion is dried, and first uses described drying plant that crucible 1 is heated to 80 DEG C, then enters Row insulation is till the described coating spraying liquid being sprayed in crucible 1 inner bottom surface is dried；In step 3, preheating time is 4h And T1=1285 DEG C, P1=100kW；In step 401 T2=1400 DEG C, in step 402 T3=1560 DEG C, t=in step 403 20min, P2=45kW；Q2=650mbar in step 4；In 1st step, temperature retention time is 0.4h；T8=in 2nd step to the 5th step 1325 DEG C, the heating-up time is 0.4h；In 6th step, T9=1460 DEG C and heating-up time are 3.5h；In 7th step T10=1510 DEG C and Heating-up time is 3.5h；In 8th step, T3=1560 DEG C and heating-up time are 3.5h；In 9th step, temperature retention time is 3.5h；10th step Middle temperature retention time is 4h.

2nd step, the first step promote: by 1285 DEG C, the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is promoted to 1290 DEG C, and heat up Time is 5min.

3rd step, second step promote: by 1290 DEG C, the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is promoted to 1295 DEG C, and heat up Time is 5min.

4th step, the 3rd step promote: by 1295 DEG C, the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is promoted to 1315 DEG C, and heat up Time is 9min.

5th step, the 4th step promote: by 1315 DEG C, the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is promoted to 1325 DEG C, and heat up Time is 5min.

In the present embodiment, in step 501 T4=1410 DEG C, temperature retention time is 25min；In step 502 T5=1435 DEG C, protect The temperature time is 15min；

In the present embodiment, the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is down to T6 through 70min by step 701, and is incubated 3h； Wherein, T6=1250 DEG C；The heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is down to T7 by T6 through 70min by step 2052, and is incubated 3h, T7=900 DEG C, Q1=180Pa,；When cooling to processed polycrystalline silicon ingot casting with the furnace room temperature, according to the cooling speed of 90 DEG C/h Rate cools down.

In the present embodiment, remaining method step and technological parameter are the most same as in Example 1.

In the present embodiment, the surface free from admixture of machine-shaping ingot casting finished product, without viscous crucible phenomenon, bottom ingot casting, oxygen content reduces More than 68%, minority carrier life time ＞ 5.5us (microsecond), Hard Inclusion ratio ＜ 0.5%, yield rate is 82%, and grain size is 7 grades.

Embodiment 3

In the present embodiment, as different from Example 1: organic cementing agent, deionized water and boron nitride are pressed by step 101 The mass ratio of 1: 2.5: 0.8 uniformly mixes, and obtains coating spraying liquid；Described organic cementing agent is epoxy adhesive；In step 102 When spraying, 1m in described crucible 1 inner bottom surface²The quality of contained boron nitride in the described coating spraying liquid of spraying in region For 130g；When step 103 is dried, use described drying plant and to being sprayed in crucible 1 under 100 DEG C of temperature conditionss Described coating spraying liquid on bottom surface, portion is dried, and first uses described drying plant that crucible 1 is heated to 100 DEG C, then Carry out being incubated till the described coating spraying liquid being sprayed in crucible 1 inner bottom surface is dried；In step 3, preheating time is 6h and T1=1125 DEG C, P1=50kW；In step 401 T2=1350 DEG C, in step 402 T3=1540 DEG C, t=in step 403 40min, P2=25kW；Q2=550mbar in step 4；In 1st step, temperature retention time is 0.6h；T8=in 2nd step to the 5th step 1190 DEG C, the heating-up time is 0.6h；In 6th step, T9=1440 DEG C and heating-up time are 4.5h；In 7th step T10=1490 DEG C and Heating-up time is 4.5h；In 8th step, T3=1540 DEG C and heating-up time are 4.5h；In 9th step, temperature retention time is 4.5h；10th step Middle temperature retention time is 8h.

2nd step, the first step promote: by 1125 DEG C, the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is promoted to 1140 DEG C, and heat up Time is 9min.

3rd step, second step promote: by 1140 DEG C, the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is promoted to 1155 DEG C, and heat up Time is 8min.

4th step, the 3rd step promote: by 1155 DEG C, the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is promoted to 1175 DEG C, and heat up Time is 10min.

5th step, the 4th step promote: by 1175 DEG C, the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is promoted to 1190 DEG C, and heat up Time is 9min.

In the present embodiment, in step 501 T4=1420 DEG C, temperature retention time is 15min；In step 502 T5=1445 DEG C, protect The temperature time is 8min；

In the present embodiment, the heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is down to T4 through 50min by step 701, and is incubated 2h, T6=1280 DEG C；The heating-up temperature of polycrystalline silicon ingot or purifying furnace 9 is down to T7 by T6 through 50min by step 702, and is incubated 2h, T7= 950℃；Q1=250Pa；When cooling to processed polycrystalline silicon ingot casting with the furnace room temperature, carry out according to the rate of temperature fall of 120 DEG C/h Cooling.

In the present embodiment, after using polycrystalline silicon ingot or purifying furnace and utilizing the crucible 1 of band base coat 2 to carry out polycrystalline silicon ingot casting, The surface free from admixture of machine-shaping ingot casting finished product, without viscous crucible phenomenon, bottom ingot casting, oxygen content reduces by more than 75%, minority carrier life time ＞ 5.5us (microsecond), Hard Inclusion ratio ＜ 0.5%, yield rate is 83%, and grain size is 6 grades.

Embodiment 4

In the present embodiment, as different from Example 1: organic cementing agent, deionized water and boron nitride are pressed by step 101 The mass ratio of 1: 2.5: 1.2 uniformly mixes, and obtains coating spraying liquid；Described organic cementing agent is Instant adhesive；In step 102 When spraying, 1m in described crucible 1 inner bottom surface²The quality of contained boron nitride in the described coating spraying liquid of spraying in region For 180g.

In the present embodiment, compared with conventional crucible, use polycrystalline silicon ingot or purifying furnace and utilize the crucible 1 of band base coat 2 to enter After row polycrystalline silicon ingot casting, the surface free from admixture of machine-shaping ingot casting finished product, without viscous crucible phenomenon, bottom ingot casting, oxygen content reduces by 72% Above, minority carrier life time ＞ 5.5us (microsecond), Hard Inclusion ratio ＜ 0.5%, yield rate is 76%.

Embodiment 5

In the present embodiment, as different from Example 1: organic cementing agent, deionized water and boron nitride are pressed by step 101 The mass ratio of 1: 2: 1.2 uniformly mixes, and obtains coating spraying liquid；Described organic cementing agent is acrylic acid adhesive；In step 102 When spraying, 1m in described crucible 1 inner bottom surface²The quality of contained boron nitride in the described coating spraying liquid of spraying in region For 200g.

In the present embodiment, compared with conventional crucible, use polycrystalline silicon ingot or purifying furnace and utilize the crucible 1 of band base coat 2 to enter After row polycrystalline silicon ingot casting, the surface free from admixture of machine-shaping ingot casting finished product, without viscous crucible phenomenon, bottom ingot casting, oxygen content reduces by 70% Above, minority carrier life time ＞ 5.5us (microsecond), Hard Inclusion ratio ＜ 0.5%, yield rate is 74%.

The above, be only presently preferred embodiments of the present invention, not impose any restrictions the present invention, every according to the present invention Any simple modification, change and the equivalent structure change that above example is made by technical spirit, all still falls within skill of the present invention In the protection domain of art scheme.

Claims

1. a polycrystalline silicon casting ingot process, it is characterised in that the method comprises the following steps:

Step one, auxiliary heater are installed: install auxiliary heater in polycrystalline silicon ingot or purifying furnace (9)；

Described auxiliary heater is the bottom heater (3) being laid in crucible (1) lower section, and described crucible (1) is cube crucible And it is that level is laid, described bottom heater (3), the top heater (2) being laid in crucible (1) top and four difference cloth The side heater (4) of four side-wall outer side being located at crucible (1) forms hexahedro heater；Described top heater (2) and Bottom heater (3) is all laid in level, four described side heater (4) all in vertically to laying；Described top heater (2), bottom heater (3) and four described side heater (4) are all laid in polycrystalline silicon ingot or purifying furnace (9)；

Step 2, charging: in crucible (1), load silicon material, and the crucible (1) of built-in silicon material is loaded polycrystalline silicon ingot or purifying furnace (9) In；

Step 3, preheating: top heater (2), bottom heater (3) and four described side heater (4) are all opened, and Use polycrystalline silicon ingot or purifying furnace (9) that the silicon material being loaded in crucible (1) is preheated, and by the heating temperature of polycrystalline silicon ingot or purifying furnace (9) Degree steps up to T1；Preheating time is 4h～6h, wherein T1=1125 DEG C～1285 DEG C；

Step 4, fusing, process is as follows:

Step 401, the hexahedro heat fusing that adds: use polycrystalline silicon ingot or purifying furnace (9) that the silicon material being loaded in crucible (1) is melted, molten Change temperature to be stepped up to T2 by T1；Wherein T2=1350 DEG C～1400 DEG C；In this step, described top heater (2), bottom Heater (3) and four described side heater (4) are in opening；

Step 402, five faces add heat fusing: use polycrystalline silicon ingot or purifying furnace (9) to continue to melt the silicon material being loaded in crucible (1) Changing, fusion temperature is stepped up to T3 by T2；Wherein T3=1540 DEG C～1560 DEG C；In this step, described top heater (2) Being in opening with four described side heater (4), described bottom heater (3) is closed；

Step 403, subsequent melting: after the silicon material in crucible (1) all melts, by the heating-up temperature of polycrystalline silicon ingot or purifying furnace (9) Controlling at T3, the heating power of the most described top heater (2) and four described side heater (4) all begins to decline, and treats The heating power of described top heater (2) and four described side heater (4) all stops declining and after persistent period t, molten Material process completes；Wherein t=20min～40min；

To long brilliant pre-treatment after step 5, fusing, process is as follows:

Step 501, cooling: the heating-up temperature of polycrystalline silicon ingot or purifying furnace (9) is down to T4 by T3, and is incubated 15min～25min；Its Middle T4=1410 DEG C～1420 DEG C；

Step 502, intensification: the heating-up temperature of polycrystalline silicon ingot or purifying furnace (9) is risen to T5 by T4, and is incubated 8min～15min；Wherein T5=1435 DEG C～1445 DEG C；

Step 6, long crystalline substance: at T5 and the heating and temperature control of polycrystalline silicon ingot or purifying furnace (9) is carried out directional solidification, until completing long Brilliant process；

Step 7, anneal and cool down: after long brilliant process completes in step 6, anneal and cool down, and obtaining machine-shaping Described polycrystalline silicon ingot casting.

2. according to a kind of polycrystalline silicon casting ingot process described in claim 1, it is characterised in that: top heater described in step one (2), bottom heater (3) and four described side heater (4) are all connected with heating power adjusting means (6)；

In step 3 in warm, use heating power adjusting means (6) to top heater (2), bottom heater (3) and The heating power of four described side heater (4) synchronizes to be stepped up；

Described top heater (2) is connected with top firing power supply (2-1) by the first electrode, four described side heater (4) being all connected with sidepiece heating power supply (4-1) by the second electrode, described bottom heater (3) passes through the 3rd electrode and bottom Heating power supply (3-1) connects；Described top firing power supply (2-1), sidepiece heating power supply (4-1) and bottom-heated power supply (3-1) All being connected with heating power adjusting means (6), described heating power adjusting means (6) is to top firing power supply (2-1), sidepiece The PCU Power Conditioning Unit that the output of heating power supply (4-1) and bottom-heated power supply (3-1) is adjusted respectively.

3. according to a kind of polycrystalline silicon casting ingot process described in claim 1 or 2, it is characterised in that: in step 3 in warm, Synchronize progressively to rise by the heating power of top heater (2), bottom heater (3) and four described side heater (4) Height, and the heating power of top heater (2), bottom heater (3) and four described side heater (4) is all stepped up To P1, wherein P1=50kW～100kW；

In step 401 in hexahedro heating fusion process, described top heater (2), bottom heater (3) and four described sidepieces The heating power of heater (4) is P1；

In step 402 in five heating fusion processes, adding of described top heater (2) and four described side heater (4) Thermal power is P1；

In step 403 subsequent melting during, after the silicon material in crucible (1) all melts, described top heater (2) and four The heating power of individual described side heater (4) synchronizes progressively to decline, to top heater (2) or side heater (4) Heating power situation of change be observed, treat that the heating power of top heater (2) or side heater (4) drops to P2 Time, keep P2 constant and after persistent period t, melt process completes；Wherein, P2=25kW～45kW.

4. according to a kind of polycrystalline silicon casting ingot process described in claim 1 or 2, it is characterised in that: step 6 is carried out grow brilliant mistake Cheng Zhong, the heat-insulation cage hoisting depth of described polycrystalline silicon ingot or purifying furnace (9) is 8cm/h～12cm/h.

5. according to a kind of polycrystalline silicon casting ingot process described in claim 1 or 2, it is characterised in that: step 6 is carried out grow brilliant mistake Cheng Zhong, be positioned in described polycrystalline silicon ingot or purifying furnace (9) heating power of top heater (2) of crucible (1) top be 80kW～ 95kW, the heating power of the side heater (4) of four four side-wall outer side being laid in crucible (1) respectively be 30kW～ 50kW；

Polycrystalline silicon ingot or purifying furnace described in step one is provided with gas chiller in (9)；During step 6 carries out long crystalline substance, logical Cross the cooling gas flow increasing described gas chiller by the heating and temperature control of polycrystalline silicon ingot or purifying furnace (9) to T5.

6. according to a kind of polycrystalline silicon casting ingot process described in claim 1 or 2, it is characterised in that: step 7 is carried out anneal and During cooling, process is as follows:

Step 701, for the first time annealing: through 50min～70min, the heating-up temperature of polycrystalline silicon ingot or purifying furnace (3) is down to T6, and is incubated 2h～3h；Wherein, T6=1250 DEG C～1280 DEG C；

Step 702, second time annealing: the heating-up temperature of polycrystalline silicon ingot or purifying furnace (3) is down to T7 by T6 through 50min～70min, and Insulation 2h～3h；T7=900 DEG C～950 DEG C；

Step 703, cooling: cool to processed polycrystalline silicon ingot casting with the furnace room temperature, it is thus achieved that the described polysilicon casting of machine-shaping Ingot.

7. according to a kind of polycrystalline silicon casting ingot process described in claim 6, it is characterised in that: step 701 is carried out move back for the first time Fire process neutralization procedure 702 is carried out, in second time annealing process, all in described polycrystalline silicon ingot or purifying furnace (9), be filled with noble gas And the air pressure in polycrystalline silicon ingot or purifying furnace is maintained at Q1, wherein Q1=180Pa～250Pa；

When step 703 cools to processed polycrystalline silicon ingot casting with the furnace room temperature, according to 90 DEG C/h～the rate of temperature fall of 120 DEG C/h Cool down.

8. according to a kind of polycrystalline silicon casting ingot process described in claim 1 or 2, it is characterised in that: in step 2, charging carries out it Before, also needing to carry out crucible bottom coating and prepare, process is as follows:

Step 101, coating spraying liquid are prepared: by organic cementing agent, deionized water and boron nitride by 1: (2～2.5): (0.8～ 1.2) mass ratio uniformly mixes, and obtains coating spraying liquid；

Step 102, spraying: use spraying equipment by the inside of the even application of coating spraying liquid described in step 101 to crucible (1) On bottom surface, 1m in described crucible (1) inner bottom surface²In region, in the described coating spraying liquid of spraying, the quality of contained boron nitride is 100g～200g；

Described crucible (1) is that polycrystalline silicon ingot or purifying furnace (9) uses silica crucible；

Step 103, drying: crucible described in step 102 (1) is placed horizontally in drying plant, and uses described drying to set It is standby and under 80 DEG C～100 DEG C of temperature conditionss, the described coating spraying liquid being sprayed in crucible (1) inner bottom surface is dried, Obtain base coat (2)；

When step 2 feeds, in the crucible (1) of band base coat (2) in load silicon material, and by the earthenware of built-in silicon material Crucible (1) loads in polycrystalline silicon ingot or purifying furnace (9).

9. according to a kind of polycrystalline silicon casting ingot process described in claim 8, it is characterised in that: organic adhesive described in step 101 Agent is phenolic aldehyde-neoprene adhesive, epoxy adhesive, Instant adhesive, acrylic acid adhesive, polyvinyl alcohol adhesive, gathers Vinyl acetate adhesive, AE SGA, butvar adhesive stick or glass cement；

Described boron nitride is hexagonal boron nitride.

10. according to a kind of polycrystalline silicon casting ingot process described in claim 8, it is characterised in that: when step 102 sprays, 1m in described crucible (1) inner bottom surface²In region in the described coating spraying liquid of spraying the quality of contained boron nitride be 100g～ 150g；

When step 103 is dried, first use described drying plant that crucible (1) is heated to 80 DEG C～100 DEG C, then protect Temperature is till the described coating spraying liquid being sprayed in crucible (1) inner bottom surface is dried.