CN102608913A - System and method for controlling blowing out of reduction furnace in production of polycrystalline silicon - Google Patents
System and method for controlling blowing out of reduction furnace in production of polycrystalline siliconDownload PDFInfo
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Abstract
Description
Technical field
The present invention relates to a kind of polysilicon producing and reducing furnace blowing out control system and method thereof.
Background technology
Polysilicon can be used as important photovoltaic material at present as a kind of semiconductor material, and photovoltaic material can be directly changed into electric energy with sun power, for example solar cell.One of main method of producing polysilicon at present is the improvement Siemens Method.The improvement Siemens Method produces rod-like polycrystal silicon through vapour deposition process.
Siemens Method reduction production well known in the prior art is: the trichlorosilane of vaporization mixes the introducing polycrystalline silicon reducing furnace by a certain percentage with carrier gas hydrogen; Bar-like silicon core two ends in being positioned over reduction furnace are voltage in addition; Under certain temperature and pressure; At the high temperature silicon wicking surface, trichlorosilane and hydrogen mixed gas reaction generting element silicon, and be deposited on the silicon wicking surface; Generate the polycrystalline silicon rod of required specification gradually, produce accessory substances such as silicon tetrachloride, dichloro-dihydro silicon, hydrogen chloride simultaneously.
After polysilicon producing and reducing furnace start-up is moving; Reaction feed (being trichlorosilane and hydrogen mixed gas) is got in the body of heater of reduction furnace by draft tube; Produce high temperature with electrode pair silicon core energising heating, usually temperature of reaction is controlled at about 1000 ℃ to 1200 ℃, be preferably about 1100 ℃.The trichlorosilane and the hydrogen that feed carry out vapor deposition reaction generting element silicon at the silicon wicking surface.The tail gas of reacted is discharged through exhaust pipe from the center of stove tube bottom.Along with the silicon that is deposited on the silicon wicking surface increases, silicon rod is chap gradually, finally grows up to the polycrystalline silicon rod of required size.After silicon rod grew into required size, for example the size of 2.0 to 2.8 meters of length, 40 to 200 millimeters of final diameters then need be carried out blowing out and handled.
The reduction furnace blowing out is the important stage in the reduction furnace production run, and harmony, stability, the security of output, quality, cost and the whole production system of polysilicon played immeasurable effect.
In original furnace stopping process, the stopping process that adopts usually at present is: evenly fellearlier material 1 ~ 3 hour, the mixture of trichlorosilane and hydrogen is reduced to 0Nm3/ h (normal cubic metre/hour) falls in the material process and keeps the silicon rod surface temperature still to be well-defined reaction temp through regulating electric current; Fall after material accomplishes, switch to pure hydrogen displacement after, beginning evenly reduces to flow through the electric current of electrode and continue 1～3 hour, after electric current is reduced to 0A, cuts off the power supply and has accomplished the blowing out operation.
Above-mentioned original furnace stopping process time spent is longer, and in furnace shutting down process, produces magnetic field because of electric current changes, and the effect that the silicon rod of energising receives magnetic force produces moment, causes the silicon rod root loosening; Different because of the crystal form of polycrystalline again, its local electrical resistance is also different, reduces identical electric current, and the variation of silicon rod local temperature is also different, because the degree difference of thermal shrinkage is slowly split silicon rod; Because of polysilicon is a semiconductor, its resistance increases with the reduction of temperature again, evenly falls electric current and can make the different temperature variation constantly of silicon rod different, causes its stress evenly not discharge; Thereby cause silicon rod short texture, local fracture, fall adverse consequences such as stove.
Summary of the invention
In order to overcome the above-mentioned shortcoming of existing stopping process; One of the object of the invention provides a kind of improved polysilicon producing and reducing furnace blowing out control system and control method; This blowing out control system and method thereof can shorten the used time of blowing out, save cost and reduce the excellent rate of falling of polycrystalline silicon rod.
In one aspect of the invention; The invention provides a kind of polysilicon producing and reducing furnace blowing out control system; Said reduction furnace comprises the silicon rod that is arranged on the chassis, and said blowing out control system comprises: the magnetic force computing module is used to calculate the maximum magnetic force that silicon rod that growth accomplishes receives; The Stress calculation module, the minimum that is used to calculate the silicon rod that growth accomplishes discharges stress; Blowing out optimal module, the maximum magnetic force that is used for receiving based on this silicon rod and the minimum of silicon rod discharge stress and utilize optimized Algorithm to calculate to optimize furnace outage time and optimize the blowing out temperature; And control module, based on optimization furnace outage time that calculates and the blowing out of optimizing blowing out temperature control reduction furnace.
In other characteristics of the present invention, the inlet amount of control module control trichlorosilane and hydrogen mixed gas, make that blowing out begins after, in optimizing furnace outage time, inlet amount is evenly reduced to zero.
In other characteristics of the present invention, control module control is through the electric current of silicon rod, make that blowing out begins after, the silicon rod temperature evenly descends.
In other characteristics of the present invention, control system also comprises the electric current computing module, and this electric current computing module is calculated electric current change curve in the furnace shutting down process based on optimizing furnace outage time with optimization blowing out thermometer.And said control module changes curve controlled electric current through silicon rod in optimizing furnace outage time based on the electric current of calculating, and makes the silicon rod temperature evenly descend.
In other characteristics of the present invention, through the optimization furnace outage time, inlet amount is reduced to zero and the silicon rod temperature is reduced to when optimizing the blowing out temperature after blowing out begins, and control system is cut off the power supply to reduction furnace.
In other characteristics of the present invention, said optimized Algorithm can be genetic algorithm.
In other characteristics of the present invention, optimizing furnace outage time is about 10 minutes to 1.3 hours scope, preferably can be 30 minutes.Optimizing the blowing out temperature is between about 750 to 970 ℃, preferably can be 878 ℃.
In second aspect of the present invention, a kind of polysilicon producing and reducing furnace blowing out control method is provided, may further comprise the steps: the maximum magnetic force that the silicon rod that calculating grows accomplishes receives; The minimum of estimating this silicon rod discharges stress; The maximum magnetic force that receives based on this silicon rod and the minimum of silicon rod discharge stress and utilize optimized Algorithm to calculate to optimize furnace outage time and optimize the blowing out temperature; With the blowing out of controlling reduction furnace based on optimization furnace outage time that calculates and optimization blowing out temperature.
In other characteristics of the present invention, the step of blowing out of control reduction furnace further comprises: the inlet amount of control trichlorosilane and hydrogen mixed gas, make that blowing out begins after, in optimizing furnace outage time, inlet amount is evenly reduced to zero.
In other characteristics of the present invention, the step of the blowing out of said control reduction furnace further comprises: when reducing inlet amount, control is through the electric current of silicon rod, make that blowing out begins after, the silicon rod temperature evenly descends.
In other characteristics of the present invention, said method also comprises based on optimizing furnace outage time calculates the step of electric current changing down in the furnace shutting down process with optimization blowing out thermometer.And the step of the blowing out of said control reduction furnace further comprises: be controlled at based on the electric current changing down of calculating and optimize in the furnace outage time through the electric current of silicon rod, make the silicon rod temperature evenly descend.
In other characteristics of the present invention, said method also comprises based on optimizing fracture, outage point, calculates inlet amount changing down and the alive changing down of silicon rod in the furnace shutting down process.
In other characteristics of the present invention, said method also comprises: after blowing out begins, through optimization furnace outage time or when having reached optimization blowing out temperature, cut off the power supply to reduction furnace.
The more areas that the present invention uses will become more obvious through the given detailed description of hereinafter.Should be appreciated that specific descriptions and specific examples only with laying down a definition and understanding purpose, still should not be used to limit scope of the present invention.
Description of drawings
To more fully understand the present invention through detailed description and accompanying drawing, wherein:
Fig. 1 is the simplified schematic diagram of polysilicon producing and reducing furnace of the present invention.
Fig. 2 is the block schematic diagram according to first embodiment of blowing out control system of the present invention.
Fig. 3 is the block schematic diagram according to second embodiment of blowing out control system of the present invention.
Fig. 4 is the computation optimization process flow diagram according to best fracture of the present invention, outage point.
Fig. 5 shows the process flow diagram of the furnace stopping process of optimization of the present invention.
Embodiment
Following detailed and accompanying drawing are described and are shown various embodiment of the present invention.These are described and accompanying drawing is used to enable those skilled in the art to make and use the present invention, are not to limit scope of the present invention by any way.Therefore about disclosed method, said step comes down to schematically, is not necessarily necessity or crucial.
Fig. 1 shows the structural representation of the polysilicon producing and reducing furnace of the present invention's employing.As shown in Figure 1, reduction furnace mainly comprisesstove tube 1, is positioned at the stone or metal plate for standing a stove on as a precaution againstfire 2 of stove tube inner bottom part, is arranged on a plurality of electrodes 3 (only illustrating two), combinationgas draft tube 5,exhaust pipe 6, cooling water inlet pipe and risingpipe like silicon cores 4, for example diameter is that 7～10 millimeters, length are 2.0 to 2.8 meters, is evenly arranged on the stone or metal plate for standing a stove on as a precaution againstfire 2, and is electrically connected with electrode 3.Can also be provided withvisor hole 9 on the stove barrel, be convenient to monitor temperature or silicon rod temperature in the stove, with the control temperature of reaction.
Because of differences such as reduction furnace structure, polysilicon product height, diameter, quality, processing parameter, production cycles, all can exert an influence to blowing out.A plurality of exemplary embodiments are described below set forth the present invention.Required silicon rod specification is for example in the scope of 2.0 to 2.8 meters of length, 40 to 200 millimeters of diameters.Start polysilicon producing and reducing furnace, in reduction furnace, feeds the combination gas of trichlorosilane and hydrogen, utilize 3 pairs of silicon cores energisings of electrode to heat so that carry out vapor deposition reaction production polysilicon on the surface of bar-like silicon core 4 through combination gas draft tube 5.Along with the continuous generation and the deposition of polysilicon, grow the silicon rod of required specification.After the polycrystalline silicon rod that has obtained required specification, start blowing out and handle.
In furnace shutting down process, as stated, the silicon rod that basic growth is accomplished can receive electric current simultaneously and reduce in the process to be changed in the magnetic force that causes and the temperature-fall period because the stress that thermal shrinkage causes by electromagnetic field.Particularly, after blowing out begins, need reduce the electric current through silicon rod gradually, electric current changes generation magnetic field, and the silicon rod of energising receives magnetic force.Silicon rod can produce and rock under the effect of magnetic force, and serious situation can make silicon rod rupture, even rod takes place.On the other hand, because of silicon rod can produce temperature variation in furnace shutting down process, meeting produces certain shrink and causes thermal stress in temperature-fall period.If do not discharge certain stress, also can produce the silicon rod cracking, increase and fall excellent probability.
In order to optimize furnace stopping process, hope that magnetic force that silicon rod receives and stress all tries one's best little and can reduce as early as possible, thereby prevent down rod.Yet, the minimum mutual contradiction of stress that discharges of maximum suffered magnetic force of silicon rod and silicon rod.This be because, in the furnace shutting down process, the electric current I through silicon rod evenly reduces gradually, magnetic induction density also reduces with electric current and reduces gradually.So, the magnetic field force that receives of silicon rod reduces and reduces gradually along with electric current.The maximum magnetic force that silicon rod receives occurs in the incipient time period of blowing out.If do not consider stress factors, when blowing out is handled, hope to reduce rapidly electric current, can eliminate the influence of magnetic force as early as possible like this to silicon rod.But it is directly related that the suffered thermal stress of silicon rod and the temperature of silicon rod reduce caused drawdown deformation, and it is fast more that temperature reduces, and caused thermal stress is big more.Therefore, there is contradiction between them.
Consider above-mentioned factor, the present invention calculates maximum suffered magnetic force of silicon rod and the minimum stress that discharges of silicon rod, based on these two factors, utilizes optimized Algorithm optimization best fracture, the outage point of blowing out processing, so that obtain optimized furnace shutting down process.
The maximum suffered magnetic force of silicon rod can calculate through the momentary current that flows through silicon rod.The stress that silicon rod receives can be calculated according to mechanics parameter, constraint condition and the loadometer of the silicon that is provided with the Stress calculation module.Then, based on maximum suffered magnetic force of the silicon rod that calculates and the minimum stress that discharges of silicon rod, utilize optimized Algorithm to calculate best fracture, outage point, promptly best blowing out temperature and required time of best blowing out.In best blowing out temperature, the suffered thermal stress of silicon rod is considered to discharge basically.That is to say that below the temperature, continue cooling at this again, silicon rod shrinks very little maybe can being left in the basket of stress that causes to be disregarded, and can not produce down rod.The scope that above-mentioned blowing out control method according to the present invention is optimized the best fracture that, outage point is generally between about 10 minutes to about 1.3 hours and between about 750 degree spend to 970.Shortened the required time of blowing out so greatly, and saved reduction furnace and produced required electric energy.
In the prior art, usually the material process will be fallen earlier: needed 1-3 hour evenly to fall material to zero; After falling the end of material process, carry out temperature-fall period again: electric current is reduced to zero through 1-3 hour.
Different with prior art is in furnace stopping process of the present invention, to reduce charging (combination gas) and reduce the suffered electric current of silicon rod and carry out simultaneously.That is to say, behind the polycrystalline silicon rod growth ending, start the blowing out stage, begin to fall material, in best furnace outage time with the even near 0Nm of inlet amount of trichlorosilane and hydrogen mixed gas3Behind/the h.Begin cooling when falling material, in this best furnace outage time, simultaneously the silicon rod temperature is evenly reduced to best blowing out temperature, outage then, furnace shutting down process finishes.
Compare prior art; One of beneficial effect of the present invention is: shorten reduction furnace and fall the material time; And shortening reduction furnace temperature fall time; And fall material process and temperature-fall period and carry out simultaneously, thereby shortened required T.T. of reduction furnace blowing out greatly, and greatly reduce inlet amount and the required energy consumption that consumes in the furnace shutting down process.
First preferred embodiment of reduction furnace blowing out control system of the present invention orcontrol device 10 is described below in conjunction with accompanying drawing 2.Control system 10 mainly comprises magneticforce computing module 20,Stress calculation module 30, blowing outoptimal module 40 andcontrol module 60.
Magneticforce computing module 20 calculates the suffered maximum magnetic force of silicon rod through the momentary current that flows through silicon rod.Stress calculation module 30 estimates the minimum stress that discharges of silicon rod according to mechanics parameter, constraint condition and the load of the silicon of setting.The connection of communicating by letter withStress calculation module 30 of blowing outoptimal module 40 and magneticforce computing module 20, and receive maximum suffered magnetic force of the silicon rod of calculating and the minimum stress that discharges of silicon rod from magneticforce computing module 20 andStress calculation module 30 respectively.Blowing out optimal module then 40 is utilized optimized Algorithm based on maximum suffered magnetic force of silicon rod and the minimum stress that discharges of silicon rod, and genetic algorithm is for example calculated the furnace outage time P of optimization (the best)OptimalAnd optimization (the best) blowing out temperature TOptimal, promptly optimize fracture, the outage point of (the best).Control module 60 configurations are used to control the whole process that blowing out is handled.Control module 60 connection of communicating by letter with blowing outoptimal module 40, and receive best furnace outage time and best blowing out temperature from blowing out optimal module 40.Control module 60 is controlled the temperature of silicon rod in furnace shutting down process, make the silicon rod temperature in best furnace outage time, evenly reduce to best blowing out temperature TOptimalMeanwhile,control module 60 is also controlled the trichlorosilane of entering reduction furnace and the inlet amount of hydrogen mixed gas evenly reduces gradually, makes that this inlet amount is reduced to 0Nm through after the best furnace outage time3/ h.At the best furnace outage time P of processOptimalAfterwards, the silicon rod temperature will be reduced to best blowing out temperature TOptimal, and inlet amount is zero, this moment,control module 60 was cut off the power supply to reduction furnace immediately, promptly cut off the electric current throughelectrode 3, thereby accomplished blowing out control.Afterwards, convert hydrogen exchange into.
Second preferred embodiment of reduction furnace blowing out control system of the present invention or control device 10 ' is described below in conjunction with accompanying drawing 3.Similar with first preferred embodiment, control system 10 ' comprises magnetic force computing module 20 ', Stress calculation module 30 ', blowing out optimal module 40 ',control module 60 '.In second preferred embodiment, control system 10 ' also preferably includes electric current computing module 50.Electriccurrent computing module 50 is designed to according to best furnace outage time POptimalWith best blowing out temperature TOptimal, calculate in furnace shutting down process to the required electric current variation that applies of silicon rod, to realize the furnace stopping process of above-mentioned optimization.
Below further combine electriccurrent computing module 50 to be described in the furnace shutting down process of the present invention Current Control to the silicon rod energising.
In the furnace shutting down process of prior art, employing reduces electric current equably usually.Because polysilicon is a semiconductor, its resistance increases with the reduction of temperature, therefore; Evenly falling electric current can make the different temperature variation constantly of silicon rod different; That is to say that electric current decline uniformly can cause uneven temperature to reduce, thereby causes the suffered stress of silicon rod evenly not discharge.
In order to overcome above-mentioned shortcoming, the present invention makes the silicon rod temperature evenly to reduce through the electric current fall off rate that control in furnace shutting down process changes.At first, size, material parameter and temperature according to generating silicon rod estimate the temperature variant resistance value R of silicon rod.The temperature variant resistance value of silicon rod also can perhaps various by rule of thumb laboratory facilities and is obtained.In order to make the silicon rod temperature evenly be reduced to best blowing out temperature from temperature of reaction, according to the thermodynamic equilibrium principle, utilize Joule law according to the silicon rod resistance value R that changes, calculate value through the silicon rod electric current I.
According to the aforementioned calculation result, in furnace shutting down process, the value of electric current I is controlled as, and the electric current changing down reduces gradually, that is, along with the process of time, the slippage of electric current reduces in the time per unit.Such Current Control not only can be optimized the suffered stress of silicon rod in the furnace shutting down process, and can also reduce electric current in the early stage in blowing out stage quickly, therefore just the acting force of magnetic force to silicon rod is reduced largely in the early stage in blowing out stage.Begin t in blowing out0The time, used current value when current value I is substantially equal to production of polysilicon.As time goes on, electric current I reduces with above-mentioned electric current changing down unevenly, makes the silicon rod temperature evenly to descend.When blowing out finishes t1The time, when promptly cutting off electric current, the silicon rod temperature reaches best blowing out temperature.
In a second embodiment, electriccurrent computing module 50 connection of communicating by letter with blowing out optimal module 40 ' receives the best furnace outage time P that optimizes from optimal module 40 'OptimalWith best blowing out temperature TOptimalAccording to thermodynamic equilibrium; Electriccurrent computing module 50 can be based on best furnace outage time and best blowing out temperature; Calculate the current value of the optimization of silicon rod energising in the furnace shutting down process or the electric current changing down of optimization according to the temperature variant resistance value R of silicon rod; Make that the silicon rod temperature can reduce equably, thereby has reduced the thermal stress of the required release of silicon rod in the furnace outage time of optimizing.
Control module 60 ' configuration is used to control the whole process that blowing out is handled.The connection of communicating by letter with electriccurrent computing module 50 of control module 60 ' and blowing out optimal module 40 '; And, receive the current value of optimization or the electric current changing down of optimization from electriccurrent computing module 50 from blowing out optimal module 40 ' best furnace outage time of reception and/or best blowing out temperature.Control module 60 ' based on the current value of optimizing or lower the size of current of rate controlled through silicon rod, makes the silicon rod temperature evenly reduce to best blowing out temperature T in furnace shutting down processOptimalMeanwhile, control module 60 ' also evenly reduces to get into the inlet amount of the trichlorosilane and the hydrogen mixed gas of reduction furnace gradually, makes that this inlet amount is reduced to 0Nm through after the best furnace outage time3/ h.At the best furnace outage time P of processOptimalAfterwards, the silicon rod temperature will be reduced to best blowing out temperature TOptimal, and inlet amount is zero, the power supply that this moment, control module 60 ' was cut off reduction furnace is promptly cut off the electric current throughelectrode 3, thereby is accomplished blowing out control.Afterwards, convert hydrogen exchange into.
The configuration of the magnetic force computing module 20 ' among second embodiment, Stress calculation module 30 ' and blowing out optimal module 40 ' and function basically with first embodiment in identical, needn't give unnecessary details at this.In this embodiment, electriccurrent computing module 50 is configured to independent module, yet as required, electriccurrent computing module 50 also can be integrated into and form a module in the control module 60 '.
In addition, the control system described in first embodiment and second embodiment or install 10,10 ' and can also comprise inlet amount computing module (not shown).The connection of can communicating by letter with blowing outoptimal module 40,40 ' of this inlet amount computing module, and receive best furnace outage time from the blowing out optimal module.Initial mixing gas inlet amount when the inlet amount computing module is arranged to according to best furnace outage time that receives and reduction furnace blowing out calculates uniform inlet amount changing down in the furnace shutting down process.Then, the connection of communicating by letter withcontrol module 60,60 ' of inlet amount computing module, and the inlet amount changing down that calculates offered control module, the charging that is used for furnace shutting down process reduces control.One skilled in the art will appreciate that the inlet amount computing module can be configured to independent module; Perhaps, as required, the inlet amount computing module also can be integrated in thecontrol module 60,60 ' and form a module.Alternatively, also the inlet amount computing module be can omit, and the inlet amount calculating and the control of furnace shutting down process realized by control module.
Below in conjunction with attaching Figure 4 and 5 reduction furnace blowing out control method of the present invention is described.Fig. 4 is the computation optimization process flow diagram according to best fracture of the present invention, outage point.Fig. 5 shows the best fracture that goes out according to computation optimization as shown in Figure 4, the process flow diagram that the outage point carries out the furnace stopping process of the present invention's optimization.
As shown in Figure 4, at step S10, calculate the minimum stress that discharges of suffered maximum magnetic force of silicon rod and silicon rod.Control advances to step S20, based on suffered maximum magnetic force of the silicon rod of calculating and the minimum stress that discharges of silicon rod, utilizes optimized Algorithm to calculate optimized furnace outage time and blowing out temperature (fracture of optimization, outage point).Optimized Algorithm for example can be a genetic algorithm.In step S30, according to optimized furnace outage time and blowing out temperature, the current value of the electric current changing down in the calculating furnace shutting down process or the variation of optimization makes that temperature can evenly be reduced to optimum blowing out temperature in said optimum furnace outage time.In step S40, the initial charge amount during according to optimized furnace outage time and reduction furnace blowing out calculates inlet amount changing down constant in the furnace shutting down process, makes inlet amount in said optimum furnace outage time, evenly reduce to zero.
As shown in Figure 5, in step S100, behind the polycrystalline silicon rod growth ending, start the polycrystalline silicon reducing furnace blowing out and handle.In step S110,, carry out furnace shutting down process control based on the furnace outage time and the blowing out temperature of the optimization that calculates among the step S20.Material falls in control, during the furnace outage time of this optimization with the even near 0Nm of inlet amount of trichlorosilane and hydrogen mixed gas3/ h.Begin cooling when falling material, in the furnace outage time of optimizing, the silicon rod temperature evenly reduced to basically the blowing out temperature of optimization.
Preferably, in step S110, control method can evenly be reduced to 0Nm with inlet amount according to the inlet amount changing down that step S40 calculates3/ h, simultaneously, the current value of the electric current changing down that calculates according to step S30 or the variation of optimization, control makes the silicon rod temperature can evenly reduce to optimized blowing out temperature through the decline of the electric current of silicon rod.
In step S120, control method judges whether to have reached optimum fracture, outage point, just judges whether to have passed through optimum furnace outage time, and perhaps whether the silicon rod temperature has descended and reach optimum blowing out temperature.If being judged as among the step S120 " be ", that is, passed through optimized furnace outage time or reached optimum blowing out temperature, so in step S130, the outage blowing out, furnace shutting down process finishes.If being judged as among the step S120 " denys " that then control turns back to step S110.
Through above-mentioned control procedure, the present invention can make the polycrystalline silicon reducing furnace blowing out handle optimization, prevented silicon rod short texture, local fracture and fallen excellent probability, shortened greatly simultaneously furnace stopping process required material time and temperature fall time fall, and saved electric power.
Ininstance 1, the silicon core of 24 pairs of silicon rods, 2 meters length is set on the stone or metal plate for standing a stove on as a precaution againstfire 2 of polysilicon producing and reducing furnace, the growth cycle of 1150 ℃ of the temperature of reaction in the production run, silicon rod is 72 hours.The required specification of polycrystalline silicon rod is about 125 millimeters of diameter, about 2 meters of length.
Move magneticforce computing module 20 of the present invention or 20 ',Stress calculation module 30 or 30 ', blowing outoptimal module 40 or 40 ' so that calculate best fracture, the outage point of furnace stopping process, promptly best blowing out required time is that about 30 minutes, best blowing out temperature are 878 ℃.
Adopt the as above growth course of processing parameter, in reduction furnace, produce the polycrystalline silicon rod of about 125 millimeters of diameter, the about 2 meters specifications of length.Behind the polycrystalline silicon rod growth ending,control module 60 or 60 ' beginning blowing out are handled.Start blowing out, begin to fall material, in 30 minutes with the even near 0Nm of inlet amount of trichlorosilane and hydrogen mixed gas3Behind/the h, switch to displacement hydrogen.Begin cooling when falling material, the silicon rod temperature evenly reduced to 878 ℃ in 30 minutes after, the outage blowing out.
Ininstance 2, the silicon core of 24 pairs of silicon rods, 2 meters length is set on the stone or metal plate for standing a stove on as a precaution againstfire 2 of polysilicon producing and reducing furnace, the required specification of polycrystalline silicon rod is: about 40 millimeters of diameter, about 2 meters of length.Temperature of reaction in the production run is identical withinstance 1 with growth cycle.
Move magneticforce computing module 20 of the present invention or 20 ',Stress calculation module 30 or 30 ', blowing outoptimal module 40 or 40 ' so that obtain best fracture, the outage point of furnace stopping process, promptly best blowing out required time is that about 10 minutes, best blowing out temperature are about 970 ℃.
Behind the polycrystalline silicon rod growth ending,control module 60 or 60 ' beginning blowing out are handled.Start blowing out, begin to fall material, in about 10 minutes with the even near 0Nm of inlet amount of trichlorosilane and hydrogen mixed gas3Behind/the h, switch to displacement hydrogen.Begin cooling when falling material, the silicon rod temperature evenly reduced to 970 ℃ in about 10 minutes after, the outage blowing out.
Ininstance 3, the silicon core of 24 pairs of silicon rods, 2.5 meters length is set on the stone or metal plate for standing a stove on as a precaution againstfire 2 of polysilicon producing and reducing furnace, the required specification of polycrystalline silicon rod is: about 125 millimeters of diameter, about 2.5 meters of length.Temperature of reaction in the production run is identical withinstance 1 with growth cycle.
Move magnetic force computing module of the present invention, Stress calculation module, blowing out optimal module so that calculate best fracture, the outage point of furnace stopping process, promptly best blowing out required time is that 38 minutes, best blowing out temperature are 871 ℃.
Behind the polycrystalline silicon rod growth ending,control module 60 or 60 ' beginning blowing out are handled.Start blowing out, begin to fall material, in 38 minutes with the even near 0Nm of inlet amount of trichlorosilane and hydrogen mixed gas3Behind/the h, switch to displacement hydrogen.Begin cooling when falling material, the silicon rod temperature evenly reduced to 871 ℃ in 38 minutes after, the outage blowing out.
Ininstance 4, the silicon core of 24 pairs of silicon rods, 2.8 meters length is set on the stone or metal plate for standing a stove on as a precaution againstfire 2 of polysilicon producing and reducing furnace, the required specification of polycrystalline silicon rod is: about 180 millimeters of diameter, about 2.8 meters of length.Temperature of reaction in the production run is identical withinstance 1 with growth cycle.
Move magnetic force computing module of the present invention, Stress calculation module, blowing out optimal module so that obtain best fracture, the outage point of furnace stopping process, promptly best blowing out required time is that about 1 hour, best blowing out temperature are about 800 ℃.
Behind the polycrystalline silicon rod growth ending,control module 60 or 60 ' beginning blowing out are handled.Start blowing out, begin to fall material, in about 1 hour with the even near 0Nm of inlet amount of trichlorosilane and hydrogen mixed gas3Behind/the h, switch to displacement hydrogen.Begin cooling when falling material, the silicon rod temperature evenly reduced to about 800 ℃ in about 1 hour after, the outage blowing out.
Technology is optimized in the blowing out that each above instance has provided under the different manufacturing parameters.It will be appreciated by those skilled in the art that according to different reduction furnace processing parameters, different required silicon rod specification etc., can obtain different optimization fractures, outage point through method of the present invention.In the common working condition scope of polysilicon producing and reducing furnace; The scope of the best fracture of furnace stopping process optimization, outage point is generally according to the present invention: the scope of best furnace outage time between 10 minutes to about 1.3 hours, the scope of best blowing out temperature between 750 degree to 970 degree.The silicon rod that grows into more carefully, short more, required release stress is few more, then the optimization power-off time of furnace shutting down process is fast more, it is high relatively more to optimize the outage temperature.
Many-sides such as the comprehensive electromagnetics of the present invention, mechanics, thermodynamics technology is improved traditional stopping process.Compare with original furnace stopping process; The invention has the beneficial effects as follows: shortened the furnace stopping process required time; Reduce the excellent rate of falling in polycrystalline silicon rod blowing out stage, improved product quality, reduced a material consumption of chlorosilane about 1.5% ~ 2.35%; Reduce the about 7 ~ 11kwh/kg-si of polysilicon list power consumption; Reduce the about 17 ~ 26kwh/kg-si of the comprehensive power consumption of polysilicon, reduce the tail gas recycle load and then improve about 5.56 % of polysilicon output, and improved harmony, security and the stability between reduction and two systems of tail gas recycle.
Although for the ease of understanding the present invention better, invention has been described according to preferred embodiment, be to be understood that under the situation that does not deviate from principle of the present invention, the present invention can implement with multitude of different ways.Therefore, the present invention is appreciated that and comprises all possible embodiment and the distortion of under the situation that does not deviate from the scope of the present invention of liking the claim qualification enclosed, implementing.
Claims (21)
1. polysilicon producing and reducing furnace blowing out control system, said reduction furnace comprises the silicon rod that is arranged on the chassis, said blowing out control system comprises:
The magnetic force computing module is used to calculate the maximum magnetic force that silicon rod that growth accomplishes receives;
The Stress calculation module, the minimum that is used to calculate the silicon rod that growth accomplishes discharges stress;
Blowing out optimal module, the maximum magnetic force that is used for receiving based on this silicon rod and the minimum of silicon rod discharge stress and utilize optimized Algorithm to calculate to optimize furnace outage time and optimize the blowing out temperature; With
Control module is based on optimization furnace outage time that calculates and the blowing out of optimizing blowing out temperature control reduction furnace.
2. control system according to claim 1 is characterized in that, the inlet amount of control module control trichlorosilane and hydrogen mixed gas, make that blowing out begins after, in optimizing furnace outage time, inlet amount is evenly reduced to zero.
3. control system according to claim 2 is characterized in that, the control of said control module is through the electric current of silicon rod, make that blowing out begins after, the silicon rod temperature evenly descends.
4. control system according to claim 2; It is characterized in that; Also comprise the electric current computing module, this electric current computing module is calculated electric current change curve in the furnace shutting down process based on optimizing furnace outage time with optimization blowing out thermometer, and; Said control module changes curve controlled electric current through silicon rod in optimizing furnace outage time based on the electric current of calculating, and makes the silicon rod temperature evenly descend.
5. according to each described control system among the claim 1-4, it is characterized in that through the optimization furnace outage time, inlet amount is reduced to zero and the silicon rod temperature is reduced to when optimizing the blowing out temperature after blowing out begins, control system is cut off the power supply to reduction furnace.
6. control system according to claim 1 is characterized in that, said optimized Algorithm is a genetic algorithm.
7. control system according to claim 1 is characterized in that, the optimization furnace outage time is 10 minutes to 1.3 hours a scope.
8. control system according to claim 7 is characterized in that, optimizing furnace outage time is 30 minutes.
9. control system according to claim 1 is characterized in that, optimizing the blowing out temperature is 750 to 970 ℃.
10. control system according to claim 9 is characterized in that, optimizing the blowing out temperature is 878 ℃.
11. a polysilicon producing and reducing furnace blowing out control method may further comprise the steps:
The maximum magnetic force that the silicon rod that calculating grows accomplishes receives;
The minimum of estimating this silicon rod discharges stress;
The maximum magnetic force that receives based on this silicon rod and the minimum of silicon rod discharge stress and utilize optimized Algorithm to calculate to optimize furnace outage time and optimize the blowing out temperature; With
Based on optimization furnace outage time that calculates and the blowing out of optimizing blowing out temperature control reduction furnace.
12. control method according to claim 11; It is characterized in that; The step of the blowing out of said control reduction furnace further comprises: the inlet amount of control trichlorosilane and hydrogen mixed gas, make that blowing out begins after, in optimizing furnace outage time, inlet amount is evenly reduced to zero.
13. control method according to claim 12 is characterized in that, the step of the blowing out of said control reduction furnace further comprises: when reducing inlet amount, control is through the electric current of silicon rod, make that blowing out begins after, the silicon rod temperature evenly descends.
14. control method according to claim 12 is characterized in that, said method also comprises based on optimizing furnace outage time calculates the step of electric current changing down in the furnace shutting down process with optimization blowing out thermometer, and,
The step of the blowing out of said control reduction furnace further comprises: be controlled at based on the electric current changing down of calculating and optimize in the furnace outage time through the electric current of silicon rod, make the silicon rod temperature evenly descend.
15. control method according to claim 11 is characterized in that, said method also comprises based on said optimization furnace outage time and optimization blowing out temperature, calculates inlet amount changing down and the alive changing down of silicon rod in the furnace shutting down process.
16., it is characterized in that said method also comprises: after blowing out begins,, cut off power supply to reduction furnace through optimization furnace outage time or when having reached optimization blowing out temperature according to each described control method among the claim 11-15.
17. control method according to claim 11 is characterized in that, said optimized Algorithm is a genetic algorithm.
18. control method according to claim 11 is characterized in that, the optimization furnace outage time is 10 minutes to 1.3 hours a scope.
19. control method according to claim 18 is characterized in that, optimizing furnace outage time is 30 minutes.
20. control method according to claim 11 is characterized in that, optimizing the blowing out temperature is 750 to 970 ℃.
21. control method according to claim 20 is characterized in that, optimizing the blowing out temperature is 878 ℃.
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