CN101759182B

CN101759182B - Method for manufacturing polysilicon

Info

Publication number: CN101759182B
Application number: CN2009101780531A
Authority: CN
Inventors: 刘逸枫; 崔树玉; 蒋文武; 钟真武; 蒋立民; 陈其国; 梁强; 陈明元; 孔营
Original assignee: Jiangsu Zhongneng Polysilicon Technology Development Co Ltd
Current assignee: Jiangsu Zhongneng Polysilicon Technology Development Co Ltd
Priority date: 2009-09-28
Filing date: 2009-09-28
Publication date: 2011-12-14
Anticipated expiration: 2029-09-28
Also published as: CN101759182A

Abstract

The invention relates to a method for manufacturing polysilicon. In the method, the polysilicon is prepared by continuously introducing mixed gas of hydrogen and gas containing silicon as raw material inlet gas into a reduction reactor and reducing the gas containing silicon by utilizing the hydrogen in the reduction reactor. The method comprises the following steps of regulating the gas input Q of the mixed gas used as the raw material inlet gas and/or regulating the mol ratio R of the hydrogen and the gas containing silicon in the mixed gas to enable the specific value Q/R to satisfy a special relational formula. Based on the manufacture method, the yield and the single process yield of the polysilicon in unit growth cycle can be enhanced, and the structure quality and a surface state of a polysilicon product are improved without needing to add the equipment cost or the production cost.

Description

Make the method for polysilicon

Technical field

The present invention relates to a kind of method of making polysilicon.

Background technology

Polysilicon is a main raw material of making products such as unicircuit substrate, solar cell.Polysilicon can be used to prepare silicon single crystal, and its deep processed product is widely used in the semi-conductor industry, as the base mateiral of devices such as artificial intelligence, control automatically, information processing, opto-electronic conversion.Simultaneously, because energy dilemma and requirement on environmental protection, the whole world just utilizes renewable energy source at active development.Sun power is the most noticeable in the renewable energy source, because its cleaning, safety, aboundresources.A kind of method of utilizing sun power is by photovoltaic effect conversion of solar energy to be electric energy.Silicon solar cell is the device based on photovoltaic effect that the most generally adopts.In addition, because the development of semi-conductor industry and solar cell, the demand of high-purity polycrystalline silicon is just constantly increased.

Polysilicon can be divided into solar level and electronic-grade by the purity classification.The polysilicon of solar level and electronic-grade can be prepared by metallurgical grade silicon, usually its basic skills is that solid-state metallurgical grade silicon is converted into certain liquefied compound that exists in the temperature range that allows, for example metallurgical grade silicon is converted into chlorosilane, then its method with highly efficient distilling being carried out the degree of depth purifies to remove impurity wherein, with reductive agents such as hydrogen the chlorosilane of purifying is reduced to elemental silicon subsequently, wherein elemental silicon is the form of polysilicon.

In the manufacturing of polysilicon, the most representative is the hydrogen reduction method of trichlorosilane, below will describe as representative.

In the hydrogen reduction method of trichlorosilane,, can enumerate the method for manufacturing polycrystalline silicon (be also referred to as Siemens Method) of Siemens in invention in 1954 as the technology of preparing of the high-purity polycrystalline silicon that is widely adopted.Its serial chemical equation is:

Si+3HCl→SiHCl ₃+H ₂ (1)

This reaction also generates by product such as silicon tetrachloride, dichloro hydrogen silicon (SiH except generation is used to produce the trichlorosilane of high-purity polycrystalline silicon ₂Cl ₂) etc.The product mixtures of above-mentioned reaction obtains the extremely low high-purity trichlorosilane logistics of foreign matter content through slightly heating up in a steamer and rectification process.

Then, make this high-purity trichlorosilane logistics and High Purity Hydrogen mix the formation mixed raw material gas according to certain proportioning, feeding is such as in the reduction reactor 1 that Fig. 1 briefly showed, on the high-purity polycrystalline silicon plug 2 of heating, take place as shown in the formula the reduction reaction shown in (2), by chemical vapour deposition, the high-purity polycrystalline silicon that generates constantly is deposited on the silicon plug 2, the diameter that makes this silicon plug 2 chap and form polycrystalline silicon rod (being designated hereinafter simply as silicon rod) gradually.

2SiHCl ₃+H ₂→Si+2HCl+SiCl ₄+H ₂ (2)

Other chlorosilane gas such as silicon tetrachloride that generate in unreacted trichlorosilane and the reaction process, discharge via pyrolysis exhaust pipe 5 together with hydrogen, HCl gas (being referred to as pyrolysis tail gas), and the optional gas adsorption tripping device that enters the rear end separates, and can circulate after trichlorosilane wherein is purified to supply with the use of reduction operation.

In reduction reactor (reduction furnace) structural representation that summary shown in Figure 1 is represented, the 1st, reduction furnace, the 2nd, the polysilicon plug, the 3rd, reduction furnace stove tube, the 4th, the mixed raw material gas inlet pipe, the 5th, the pyrolysis exhaust pipe, the 6th, the reduction furnace chassis, 7 are used to the electrode of polysilicon plug (or silicon rod) energising.

In order to make polysilicon, have the high purity except requiring raw material, the operational condition of reduction process is also very important.

Production practice according to polysilicon know that the proportioning of hydrogen and trichlorosilane (mol ratio) is one of important factor of decision reduction reaction, all considerable influence can be arranged to the casting yield of polysilicon and the texture quality of polysilicon.If during according to the stoichiometric ratio charging shown in the aforementioned formula (2), the polysilicon yield can reduce, on silicon rod sedimentary crystallization tiny, the surface is furvous, separates out loose armorphous dun powder sometimes.In this case, not only Zhi Bei polysilicon structure is second-rate, and because the once through yield of polysilicon is lower, unreacted inventory increases or by product increases, and has increased the reclaimed materials expense of rectifying purifying once more.In addition, for keeping the normal operation of reducing apparatus, to the demand increase of raw material.

In addition, the chemical vapour deposition reaction that carries out in reduction reactor is comparatively complicated, carrying out with deposition reaction, the silicon rod diameter increases, the turbulent flows variation, the effect of boundary layer of deposition carrier surface strengthens, make the silicon rod growth inhomogeneous, easily form the structure interlayer simultaneously, crystal grain is with loose, coarse form deposition, and then develop into plethora (being puffed rice), come across more silicon rod top (upper end portion of silicon rod among Fig. 1, promptly, that section silicon rod near reduction reactor top one side, especially near the position the silicon rod crossbeam that with dashed lines A-A or B-B indicate among Fig. 1), make that the polycrystalline silicon growth on this top is slow and loose not fine and close, follow-up corrosion is cleaned, the crystal pulling operation causes difficulty.

Though by increasing the mol ratio of hydrogen and trichlorosilane, can reduce the generation of this class side reaction, improve the once through yield of polysilicon, useful to sedimentary crystal property simultaneously, make crystallization bigger, the silicon rod surface presents brighter metalluster, helps to improve the texture quality of silicon rod, still, excessive mol ratio can cause the decline of sedimentation rate, polysilicon output in the unit's of making growth cycle descends, thereby causes the power consumption expense of unit product to rise, and the cost of unit product is increased.

In addition, as the output that improves polysilicon and the another kind of method of once through yield, U.S. Patent application US2007/0251455 also discloses a kind of method of making polysilicon, it adopts the big lithosomic body of surface-area, as big area silicone tube etc. is heating element, to shorten depositing time, improved the output of polysilicon and the once through yield of reaction thus, annual production can increase 30-40%.According to this U.S. Patent application, having adopted a kind of external diameter is that the hollow silicone tube of 50mm is a heating element.But, prepare this hollow silicone tube and generally must adopt EFG (Edge Defined Film Feed) method, this adopts silicon plug stove to prepare heating element with respect to conventional polysilicon manufacturers, need extra increase equipment and device, and the preparation of the so big hollow silicone tube of external diameter is all higher for equipment and operational requirement.

Therefore, the present situation of prior art is, still needs a kind of simple and effective method for manufacturing polycrystalline silicon, and it can improve the output of polysilicon in the unit growth cycle and the once through yield of reaction, and improve the texture quality of polysilicon product, and needn't additionally increase equipment cost or production cost.

Summary of the invention

The present inventor is by discovering, the ratio of the mol ratio of hydrogen and silicon-containing compound satisfies certain relational expression in air input by making mixed raw material gas in the manufacture method of polysilicon and the mixed gas, just can solve foregoing problems, and finish the present invention thus.

Therefore, the present invention relates to the content of following aspect:

1, a kind of method of making polysilicon, it is by feeding continuously the mixed gas that is made of hydrogen and silicon-containing gas as the raw material air inlet in reduction reactor, in described reduction reactor, utilize the described silicon-containing gas of described hydrogen reducing, make the method for polysilicon thus, it is characterized in that, may further comprise the steps:

By regulating air input Q, and/or regulate the mol ratio R of hydrogen described in the described mixed gas and described silicon-containing gas, make the ratio Q/R of described air input Q and described mol ratio R satisfy following relational expression as the described mixed gas of raw material air inlet,

Q _t1/R _t1≥Q _t2/R _t2

In described relational expression, described Q _T1Refer to from described manufacture method and begin moment through t1 hour, as the air input of the described mixed gas of raw material air inlet, unit is Nm ³/ h, described R _T1Refer to from described manufacture method and begin t1 hour the moment of process, the mol ratio of hydrogen and described silicon-containing gas described in the described mixed gas, described Q _T2Refer to from described manufacture method and begin moment through t2 hour, as the air input of the described mixed gas of raw material air inlet, unit is Nm ³/ h, described R _T2Refer to from described manufacture method and begin moment through t2 hour, the mol ratio of hydrogen and described silicon-containing gas described in the described mixed gas, wherein said t1 is an arithmetic number, described t2 is 0 or arithmetic number, and t1＞t2.

2, as aspect 1 described method, it is characterized in that, in the process of described manufacture method, have at least one t3 constantly, and described ratio Q/R satisfies following relational expression,

Q _t1/R _t1＞Q _t3/R _t3

In described relational expression, described Q _T3Refer to from described manufacture method and begin moment through t3 hour, as the air input of the described mixed gas of raw material air inlet, unit is Nm ³/ h, described R _T3Refer to from described manufacture method and begin moment through t3 hour, the mol ratio of hydrogen and described silicon-containing gas described in the described mixed gas, wherein said t3 is 0 or arithmetic number, and t1＞t3.

3, the described method of either side as described above is characterized in that described silicon-containing gas is a chlorosilane.

4, the described method of either side as described above is characterized in that described chlorosilane is trichlorosilane or silicon tetrachloride, or any mixture of the two.

5, the described method of either side as described above is characterized in that described R _T1, described R _T2With described R _T3Identical or different, be selected from 1.8-40 independently of one another.

6, the described method of either side as described above is characterized in that described R _T1, described R _T2With described R _T3Identical or different, be selected from 3-30 independently of one another.

7, the described method of either side as described above is characterized in that described R _T1, described R _T2With described R _T3Identical or different, be selected from 3.2-20 independently of one another.

8, the described method of either side as described above is characterized in that described Q _T1, described Q _T2With described Q _T3Identical or different, be selected from 20～3000Nm independently of one another ³/ h.

9, the described method of either side as described above is characterized in that described Q _T1, described Q _T2With described Q _T3Identical or different, be selected from 50～2500Nm independently of one another ³/ h.

10, the described method of either side as described above is characterized in that described Q _T1/ R _T1, described Q _T2/ R _T2With described Q _T3/ R _T3Be selected from 5～400 independently of one another.

11, the described method of either side as described above is characterized in that described Q _T1/ R _T1, described Q _T2/ R _T2With described Q _T3/ R _T3Be selected from 10～350 independently of one another.

12, the described method of either side as described above is characterized in that described Q _T1/ R _T1, described Q _T2/ R _T2With described Q _T3/ R _T3Be selected from 12～300 independently of one another.

The invention effect

Manufacturing method according to the invention, can directly utilize existing polysilicon producing apparatus to implement, therefore do not need to increase auxiliary facility for this reason and specially or change device structure, can avoid additional equipment investment cost and scrap build cost thus, owing to do not increase the complexity of polysilicon producing apparatus, the maintenance cost that yet can keep this producing apparatus does not increase simultaneously.

Manufacturing method according to the invention can improve the output of the once through yield and the interior polysilicon of unit growth cycle of polysilicon when keeping higher polysilicon deposition speed, reduced the unit cost of production of polysilicon thus.In addition, manufacturing method according to the invention owing to improved the utilization ratio of raw material silicon-containing compound such as trichlorosilane, can reduce the production of by-products amount, thereby reduced the load of subsequent disposal operation, and helped finally reducing the comprehensive production cost of polysilicon.

Manufacturing method according to the invention, by strengthening the turbulent flows of mixed raw material gas air inlet, reduce or eliminated effect of boundary layer, polysilicon grain can be deposited on silicon rod with fine and close, uniform form, improved the texture quality on silicon rod (especially silicon rod top) thus, and make configuration of surface obviously improve (the puffed rice phenomenon significantly reduces, especially near the crossbeam of silicon rod).

Description of drawings

Fig. 1 is the structural representation of the reduction reactor (reduction furnace) that uses in the method for manufacturing polycrystalline silicon of prior art.

The cross-section photograph figure (silicon rod section of beam photo figure) that Fig. 2 is the silicon rod made according to embodiment 1 when dotted line B-B shown in Figure 1 blocks.

Fig. 3 is the photo figure according to the condition of surface of the silicon rod of embodiment 1 manufacturing.

Fig. 4 is the generalized schematic of a kind of discontinuous variation pattern that the present invention relates to.

Embodiment

At first, the present invention relates to a kind of method of making polysilicon, it is by feeding continuously the mixed gas that is made of hydrogen and silicon-containing gas as the raw material air inlet in reduction reactor, in described reduction reactor, utilize the described silicon-containing gas of described hydrogen reducing, make the method for polysilicon thus, it is characterized in that, may further comprise the steps:

Q _t1/R _t1≥Q _t2/R _t2

There is at least one t3 constantly in embodiment preferred according to the present invention in the process of described manufacture method, and described ratio Q/R satisfies following relational expression,

Q _t1/R _t1＞Q _t3/R _t3

According to the present invention, structure to described reduction reactor, type and specification etc. without any qualification, can be conventional those that use in this area, and as long as it can receive the mixed gas that is made of hydrogen and silicon-containing gas continuously, and allow this mixed gas therein reduction reaction to take place and generate the polysilicon pyrolysis tail gas of by product (and as) to get final product, such as enumerating structure shown in Figure 1 (reduction furnace), but be not limited to this, also can be the reduction apparatus of other structures well known by persons skilled in the art or type, comprise such as fluidized-bed reactor etc.

Those skilled in the art know that described pyrolysis tail gas is discharged outside the described reduction reactor continuously via conventional means after described reduction reaction.

For convenience's sake, the reduction reactor (reduction furnace) with structure shown in Figure 1 below is that example is launched explanation to manufacture method of the present invention.But it is pointed out that manufacture method of the present invention is not limited to use the reduction reactor of this ad hoc structure.Obviously be understandable that for those skilled in the art,, also can be directly applied for reduction apparatus, comprise such as fluidized-bed reactor etc. in these unspecified other types or structure even the following description content is not done any adjustment or correction.

According to the present invention, described mixed gas is mixed according to certain molar ratio by hydrogen and silicon-containing gas.For the hybrid mode of hydrogen and described silicon-containing gas without any qualification, can adopt the ordinary skill in the art to carry out, so long as before entering described reduction reactor, hydrogen and described silicon-containing gas have mixed fully equably and have formed the technology of mixed gas, can directly use.

In a preferred embodiment, the preferred chlorosilane of described silicon-containing gas, more preferably trichlorosilane, silicon tetrachloride or its mixture, most preferably trichlorosilane arbitrarily.Well known in the art is that described hydrogen and described silicon-containing gas (when using with form of mixtures, referring to every kind of component in this mixture) preferably have high purity (such as more than 99%, but being not limited to this).

After this mixed gas fed reduction furnace 1 continuously by mixed raw material gas inlet pipe 4 (or other suitable intake ductings), contact with polysilicon plug 2 (or other suitable surface in contacts) because of the energising preheating, on these polysilicon plug 2 surfaces (or described other surface in contact), hydrogen and described silicon-containing gas recur the reduction reaction shown in the aforementioned formula (2), by chemical vapour deposition, the high-purity polycrystalline silicon that generates constantly is deposited on the silicon plug (or described surface in contact), and the deposit thickness that makes this silicon mandrel surface (or described surface in contact) go up polysilicon constantly increases (such as the diameter that shows as plug chap gradually) and forms silicon rod or polysilicon product.

The present invention relates to improvement to existing method for manufacturing polycrystalline silicon.Therefore, in method for manufacturing polycrystalline silicon of the present invention, unless special explanation is arranged, except regulate air input Q according to regulation of the present invention as the described mixed gas of raw material air inlet, and/or the mol ratio R of hydrogen described in the described mixed gas of adjusting (preferred synchronization regulation) and described silicon-containing gas, described ratio Q/R is satisfied beyond the specific relational expression of the present invention, the method condition that other are all, require and parameter etc. (comprises temperature of reaction, reaction pressure, conversion unit structure and configuration are such as the parameter of reduction reactor or reduction furnace, the parameter of polysilicon plug etc., ingredient requirement, method operation steps etc.) all can directly be suitable for the method for manufacturing polycrystalline silicon of prior art, not repeat them here.Those skilled in the art can understand these contents with reference to the correlation technique of prior art fully.

This fact also shows, manufacturing method according to the invention, can directly utilize existing polysilicon producing apparatus to implement, therefore do not need to increase auxiliary facility for this reason and specially or change device structure, can avoid additional equipment investment cost and scrap build cost thus, owing to do not increase the complexity of polysilicon producing apparatus, the maintenance cost that yet can keep this producing apparatus does not increase simultaneously.

According to the present invention, without any special qualification, can directly be suitable for conventional those that use in this area to the regulating measure of described mixed gas air input Q or mode.Such as, can lead to the aperture size of the valve of setting up on the inlet pipe (such as the inlet pipe among Fig. 1 4) of described reduction furnace or reduction reactor by regulating described mixed gas, perhaps regulate described mixed gas in the usual way to the supply of described reduction reactor etc., just can regulate easily from production of polysilicon and begin to producing the growth cycle that finishes each air input Q under t constantly _t, such as aforesaid Q _T1, Q _T3And Q _T2In addition, this air input is such as monitoring in real time by the under meter that is attached on the described inlet pipe, that is, monitoring begins to producing the air input Q under each moment t the growth cycle that finishes from production _t, such as aforesaid Q _T1, Q _T3And Q _T2, these all are the conventional known technology of those skilled in the art.

In one embodiment of the invention, as the variation range of the air input Q of the described mixed gas of unstripped gas such as being 20～3000Nm ³/ h, preferred 50～2500Nm ³/ h, but be not limited to this sometimes.

According to method for manufacturing polycrystalline silicon of the present invention, after producing described mixed gas, it is fed in the described reduction reactor continuously.Described mixed gas is pre-mixed according to certain molar ratio R by hydrogen and described silicon-containing gas and forms.In one embodiment of the invention, in described mixed gas, the mol ratio R of hydrogen and described silicon-containing gas (preferred trichlorosilane) changes in the scope of 1.8-40, preferred 3-30, and more preferably 3.2-20, but be not limited to this sometimes.

According to the present invention, to the regulative mode of described mol ratio R or means without any qualification, can directly be suitable for conventional those that use in this area.Such as, by when mixing, controlling hydrogen and silicon-containing gas feed molar ratio (ratio of mixture) separately in a conventional manner, can freely regulate described mol ratio R, and with its at a time t feed down in the described reduction reactor (perhaps on-line mixing time feed in the described reduction reactor), i.e. the may command mol ratio R under the t constantly _t(such as aforesaid R _T1, R _T3And R _T2), these all are that those skilled in the art can know.

According to an embodiment of the invention, by regulate air input Q according to aforesaid usual manner as the described mixed gas of raw material air inlet, and/or regulate the mol ratio R of hydrogen described in (preferred synchronization regulation) described mixed gas and described silicon-containing gas according to aforesaid usual manner, make the ratio Q/R of described air input Q and described mol ratio R satisfy following relational expression

Q _t1/R _t1≥Q _t2/R _t2

According to this embodiment, in the whole manufacture method process (production cycle) of described polysilicon, in any time of described manufacture method, the ratio Q/R that inscribes when keeping this does not reduce with respect to the corresponding Q/R value under any time before this moment.

Q _t1/R _t1＞Q _t3/R _t3

According to this embodiment, in the whole manufacture method process of described polysilicon, there is at least one t3 constantly, described ratio Q/R is that starting point begins to increase with this moment t3, and any time of remaining manufacture method after this increases, the ratio Q/R that inscribes when keeping this does not reduce with respect to the corresponding Q/R value under any time of (but after this increase) before this moment.In other words, described ratio Q/R just no longer reduces after increasing.

In the context of the present invention, described moment t (such as aforesaid t1 hour, t2 hour, t3 hour etc.) is the value of calculating by the hour, refers to from polysilicon manufacturing (0 constantly, in other words t=0) through t hour the moment.

According to the present invention, t2 and t3 are identical or different, when being limited to 0 under it, and the moment of representing described manufacture method to begin.In addition, t1 is greater than 0, and the moment T that finishes with whole manufacture method (be following growth cycle, in hour) is the upper limit.Wherein, t2 and t3 are all less than T.

In the context of the present invention, T refers to the Cycle Length (beginning time of finishing to the polysilicon manufacturing, i.e. growth cycle from the polysilicon manufacturing) of described method for manufacturing polycrystalline silicon, in hour.Those skilled in the art know that described growth cycle is generally 15-200 hour (span that is described T is 15-200 hour, preferred 60-140 hour), but according to the practical situation of producing, is not limited to this sometimes.

As previously mentioned,, ratio Q/R is increased once at least, and after this increases, keep this ratio not reduce in during after this remaining, just can realize the present invention by whole growth at polysilicon according to the present invention.

Though it is pointed out that described Q/R ratio is that (unit is Nm by calculating Q ³/ h) and the ratio of R (zero dimension) obtain, but for fear of obscuring with other possible parameters, this ratio uses by zero dimension.

According to the present invention, by in aforementioned range, regulating air input Q as the described mixed gas of raw material air inlet, and/or the mol ratio R of hydrogen described in the described mixed gas of adjusting in aforementioned range (preferred synchronization regulation) and described silicon-containing gas, make its ratio Q/R 5～400 (preferred 10～350, more preferably 12～300, but be not limited to this sometimes) change in the scope.

According to the present invention, described ratio Q/R is the result of variations of described air input Q and described mol ratio R.The Changing Pattern of described air input Q (through the time Changing Pattern) and the Changing Pattern of described mol ratio R (through the time Changing Pattern) determine after, the mol ratio R value of inscribing when the air input Q value of inscribing when a certain and this, just can calculate its ratio Q/R, the Changing Pattern of described thus ratio Q/R (through the time Changing Pattern) also just determined.So, below only a Changing Pattern and the variation pattern of described air input Q and described mol ratio R is specifically described.

To the variation pattern of described air input Q and described mol ratio R without any qualification, can be to change continuously or discontinuous variation.

As described continuous variation such as enumerating, whole growth at described polysilicon (promptly began to finish to manufacture method from manufacture method) in the cycle, described air input Q or described mol ratio R change as Changing Pattern continuously with single a kind of linear function (that is, linear function or linear function) or single a kind of nonlinear function (such as secondary or curvilinear function such as function repeatedly).

In the context of the invention, aforementioned functions is defined as Changing Pattern.

As described discontinuous variation such as enumerating, (promptly begin to finish) in the cycle in the whole growth of described polysilicon to manufacture method from manufacture method, described air input Q (or described mol ratio R) the different variation phases (with described air input Q or described mol ratio R with single a kind of aforementioned linear function or single a kind of aforementioned nonlinear function as Changing Pattern and continually varying is called the variation phase complete period) in change according to different Changing Pattern (referring to aforesaid linear function and aforesaid nonlinear function).

It is pointed out that according to the present invention described linear function or nonlinear function are continuous function in the finite interval of described variation phase regulation.

According to the present invention, in the cycle, there is one at least in the described variation phase, perhaps exists a plurality of in the whole growth of described polysilicon.

According to the present invention, time length of described variation phase of described air input Q (or described mol ratio R) is designated as Δ _{Q becomes}(or Δ _{R becomes}, unit is hour, below for for the purpose of the concise explanation, sometimes it is referred to as Δ _Become).Can exist described air input Q (or described mol ratio R) not change period of (constant) between two variation phases in succession, (its time length is designated as Δ respectively to be referred to as stationary phase _{Q is steady}Or Δ _{R is steady}, unit is hour, below for for the purpose of the concise explanation, sometimes it is referred to as Δ _Surely).With regard to this technical meaning, between two variation phases in succession, there is a stationary phase, present the variation pattern that variation phase and stationary phase alternately occur thus.

According to the present invention, in the cycle, can exist one or more described stationary phase, also can not exist in the whole growth of described polysilicon.

According to the present invention, the growth cycle of described polysilicon can be initial (or end) with the stationary phase of described air input Q or described mol ratio R, can be initial (or end) with its variation phase also, does not have any qualification.

According to the present invention, in the whole growth of described polysilicon in the cycle, described Δ _BecomeAt least there is one, and described Δ _SurelyDo not exist or can exist one or more, and described Δ _BecomeAnd Δ _SurelySatisfy following relational expression.

0≤Δ _Become≤ T, 0≤Δ _Surely＜T

That is, when some Δs _BecomeWhen getting 0 hour, i.e. the time length that this time changes the phase is 0 hour, and then this time is changed to pulsed or stepped.Work as Δ _BecomeWhen getting T hour, then in the whole growth of described polysilicon in the cycle, described Δ _Become(refer to Δ _{Q becomes}Or Δ _{R becomes}) only there is one, and the described variation of described air input Q or described mol ratio R is promptly simplified and is become aforesaid continuous variation.When some Δs _SurelyWhen getting 0 hour, i.e. the time length of this time stationary phase is 0 hour, and then two variation phases in succession are to be connected continuously, do not have stationary phase therebetween.

According to the present invention, preferred described Δ _SurelyBe not T hour, promptly preferably do not have described air input Q or described mol ratio R invariable situation in the whole growth period T of described polysilicon.

For the purpose of understanding for convenience, Fig. 4 illustrates a kind of form (that is, in the whole growth period T of polysilicon, described air input Q or described mol ratio R be the variation pattern of t in time) of this discontinuous variation in the mode of generalized schematic.In this Fig. 4, X-coordinate is represented the elapsed time (with the terminal point of T as this time) of method for manufacturing polycrystalline silicon, and ordinate zou is represented described air input Q or described mol ratio R.Wherein, at each described Δ _SurelyDuring this time, Q or R keep some steady state values constant, and at each described Δ _BecomeDuring this time, Q or R change according to single a kind of specific aforementioned linear function (but be not limited to this, also can be any one aforesaid nonlinear function etc.).

According to the present invention, among preferred described air input Q and the described mol ratio R any or when changing simultaneously, regulate changing value make described ratio Q/R increase thereupon (such as, when changing at the same time, rangeability by making described air input Q and described mol ratio R or Changing Pattern etc. are different, and make the corresponding increase of described ratio Q/R), though thereby avoided taking necessary adjusting operation to make described air input Q and/or described mol ratio R change, but do not cause the corresponding increase of described ratio Q/R (can't obtain expected effect of the present invention thus), waste described adjusting operation thus.

According to an embodiment of the invention, at described variation phase (Δ _Become) during in, described air input Q or described mol ratio R can increase or reduce, also can be the change type that increases and reduce successively or alternately occur etc., this depends on aforementioned linear function or the monotonicity of nonlinear function in the finite interval of this variation phase defined.But,, preferably do not exist described air input Q to reduce and situation that described mol ratio R meanwhile increases in order to ensure must increasing of described ratio Q/R.In addition, based on same reason, when described air input Q and described mol ratio R increase simultaneously, the amplification of preferred described air input Q is greater than the amplification of described mol ratio R, and when described air input Q and described mol ratio R reduced simultaneously, the amount of decrease of preferred described air input Q was less than the amount of decrease of described mol ratio R.

According to an embodiment of the invention, in the cycle, described air input Q and described mol ratio R change and synchronism stability synchronously in the whole growth of described polysilicon.Promptly, in the whole growth of described polysilicon in the cycle, described air input Q and described mol ratio R have the variation phase and the stationary phase of identical number, and the moment of the moment that begins each corresponding variation phase and stationary phase and end identical or overlapping (sharing variation phase and stationary phase).

Therefore, further preferred embodiment according to the present invention, in each common variation phase, the synchronous variation of described air input Q and described mol ratio R, by regulate changing value make described ratio Q/R increase (such as, by making described air input Q and described mol ratio R rangeability or the Changing Pattern etc. in this variation phase different), though thereby avoided taking necessary adjusting operation to make described air input Q and described mol ratio R change synchronously, but do not cause the corresponding increase of described ratio Q/R (can't obtain expected effect of the present invention thus), waste described adjusting operation thus.

Therefore, according to further preferred embodiment of the present invention, in the whole growth of described polysilicon in the cycle, the inevitable and described air input Q of described ratio Q/R and described mol ratio R changes synchronously and synchronism stability (wherein said air input Q and described mol ratio R also variation and synchronism stability) synchronously.In this case, with regard to each common changes phase and stationary phase, Δ _{Q becomes}=Δ _R _Become=Δ _{Q/R becomes}, Δ wherein _{Q/R becomes}Represent the time length of this variation phase of described ratio Q/R, and Δ _Q _Surely=Δ _{R is steady}=Δ _{Q/R is steady}, Δ wherein _{Q/R is steady}Represent the time length of this stationary phase of described ratio Q/R.

According to the present invention, each described Δ _Become(comprise Δ _{Q becomes}, Δ _{R becomes}And Δ _{Q/R becomes}) be selected from 0.5 hour to T hour independently of one another, preferred 1 hour to (2/3) T hour, and more preferably 2 hours to (1/2) T hour, and further preferred 5 hours to 60 hours, also further preferred 15 hours to 40 hours; And, each described Δ _Surely(comprise Δ _{Q is steady}, Δ _{R is steady}And Δ _{Q/R is steady}) be selected from 0 hour independently of one another to (2/3) T hour, preferred 0 hour to (1/2) T hour, and more preferably 0.5 hour to 30 hours, further preferred 0.5 hour to 20 hours, also further preferred 1 hour to 10 hours.Based on the accessibility and the production practical situation of producing, those skilled in the art can determine described Δ arbitrarily based on predetermined polycrystalline silicon growth period T _BecomeWith described Δ _SurelyValue, and not necessarily be limited to the scope of aforementioned regulation, and also can obtain aforementioned effect of the present invention equally.

As previously mentioned, according to the present invention, in the whole growth of described polysilicon in the cycle, described Δ _BecomeAt least there be one (preferably have 2-100, more preferably have 3-70, more preferably have 3-40), and described Δ _SurelyThere are not or can exist one or more (preferably have 0-40, more preferably have 0-20, further preferably have 0-10).Based on described Δ _BecomeWith described Δ _SurelyAforementioned numerical range and property convenient for production, those skilled in the art can determine described Δ in this growth cycle arbitrarily based on predetermined polycrystalline silicon growth period T _BecomeWith described Δ _SurelyNumber, and be not necessarily limited to aforesaid scope, and also can obtain aforementioned effect of the present invention equally.

According to the present invention clearly, all Δs _{Q becomes}Value and all Δs _{Q is steady}The value sum equals aforementioned T value, all Δs _{R becomes}Value and all Δs _{R is steady}The value sum equals aforementioned T value, and all Δs _{Q/R becomes}Value and all Δs _Q/R _SurelyThe value sum equals aforementioned T value.

According to the present invention, when there being when a plurality of each Δ _{Q is steady}Value (or Δ _{Q becomes}Value) can be identical, also can be different; When there being when a plurality of each Δ _{R is steady}Value (or Δ _{R becomes}Value) can be identical, also can be different; Correspondingly, when there being when a plurality of each Δ _{Q/R is steady}Value (or Δ _{Q/R becomes}Value) can be identical, also can be different.

According to a particularly preferred embodiment according to the invention, simplicity for implementation and operation, as the aforementioned linear function of the Changing Pattern of described air input Q and described mol ratio R or nonlinear function (preferred linear function) preferably monotone increasing or monotone decreasing, but be not limited to this sometimes.

With regard to described air input Q,, such as can enumerating following expression formula, but be not limited to this as the described linear function (continuous function) in certain variation phase.

Q＝ax+b

Perhaps, as the described quadratic function (continuous function) in this variation phase, such as enumerating following expression formula.

Q＝x ²+ax+b

With regard to described mol ratio R,, such as can enumerating following expression formula, but be not limited to this as the described linear function (continuous function) in certain variation phase.

R＝cy+d

R＝y ²+cy+d

In aforementioned expression formula, x represents any time of this variation phase of air input Q interior (beginning to finish to the variation phase from the variation phase), i.e. 0≤x≤Δ _{Q becomes}, on behalf of the Q value of the zero hour this variation phase, b (be designated as Q _Beginning), aforementioned numerical range and the aforementioned preferred value scope stipulated at air input Q before being selected from; Equally, y represents any time of this variation phase of mol ratio R interior (beginning to finish to the variation phase from the variation phase), i.e. 0≤y≤Δ _{R becomes}, on behalf of the R value of the zero hour this variation phase, d (be designated as R _Beginning), at the aforementioned numerical range and the aforementioned preferred value scope of mol ratio R regulation, and a and c are not 0 real number before being selected from.Wherein, preferred y=x.

A, b, c and d are such as determining easily in the following way.

For for simplicity, when enforcement is of the present invention, according to practical situation and the actual needs produced, pre-determine the growth cycle T of polysilicon, determine (can to determine arbitrarily and do not need special regulation based on this growth cycle then, as long as can produces and realize or suitable based on certain reason to those skilled in the art, and this does not influence the realization of effect of the present invention) Q and the variation phase of R and the appearance order of stationary phase and each variation phase and stationary phase of suitable number.Then, suitably determine (can determine arbitrarily and do not need special regulation according to accessibility of producing and practical situation, as long as can produces and realize or suitable based on certain reason to those skilled in the art, and this does not influence the realization of effect of the present invention) the time length Δ of each variation phase and each stationary phase _Become(comprise Δ _{Q becomes}And Δ _{R becomes}) and Δ _Surely(comprise Δ _{Q is steady}And Δ _{R is steady}).

According to the practical situation of producing, the Q when each variation phase that those skilled in the art can preestablish Q arbitrarily begins _BeginningQ when value (changing the b value of phase) and end corresponding to this _EventuallyValue, and do not influence the realization of effect of the present invention comprises that Q value when whole method for manufacturing polycrystalline silicon has just begun is (corresponding to the Q of first variation phase _BeginningQ value when value) and fully finishing (changes the Q of phase corresponding to last _EventuallyValue).Be with regard to each specific variation phase, to make Q easily _EventuallyBe Q _BeginningQ doubly, wherein said q is greater than 0 and is less than or equal to any real number in 150 scopes, any real number in preferred 0.1 to 100 scope; According to the number of described variation phase, described q may be any real number in the following scope: 0.3-100,0.5-50,0.8-20,1-9 and 2-6.Then, change the time length Δ of phase according to this _{Q becomes}, this changes the aforementioned Q of phase _EventuallyValue and aforementioned b value (Q that should the variation phase _BeginningValue), just can calculate a value of this variation phase based on aforementioned specific linear function or quadratic function expression formula, determine the aforementioned expression formula of this linear function or quadratic function thus, these all are that those skilled in the art are easy to realize.

After described expression formula is determined, in its corresponding variation phase, regulate described air input Q as Changing Pattern with this expression formula, just can implement the inventive method.Described adjusting can manually realize or computer program-control is realized, not special restriction.

According to the present invention, the Changing Pattern of described air input Q is not limited to the aforementioned specific linear function or the expression formula of quadratic function, also can be other forms of linear function or the nonlinear function that meets the present invention's regulation, and also can obtain aforementioned effect of the present invention equally.And those skilled in the art obviously can not give unnecessary details at this based on determining the expression formula of described other forms of linear function or nonlinear function with aforementioned similar calculation procedure.

Clearly, the Q of previous variation phase _EventuallyValue is the Q of next variation phase _BeginningValue.In addition, all aforementioned these Q _EventuallyValue and Q _BeginningValue all is selected from before the present invention aforementioned numerical range and the aforementioned preferred value scope at air input Q defined independently of one another.

In addition, according to the practical situation of producing, the R when each variation phase that those skilled in the art can preestablish R arbitrarily begins _BeginningR when value (changing the d value of phase) and end corresponding to this _EventuallyValue, and do not influence the realization of effect of the present invention comprises that R value when whole method for manufacturing polycrystalline silicon has just begun is (corresponding to the R of first variation phase _BeginningR value when value) and fully finishing (changes the R of phase corresponding to last _EventuallyValue).Be with regard to each specific variation phase, to make R easily _EventuallyBe R _BeginningR doubly, wherein said r is greater than 0 and is less than or equal to any real number in 22 scopes, any real number in preferred 0.1 to 10 scope; According to the number of described variation phase, described r may be any real number in the following scope: 0.2-10,0.3-6,0.5-4.8,0.7-3.5 and 1-3.Then, change the time length Δ of phase according to this _{R becomes}, this changes the aforementioned R of phase _EventuallyValue and aforementioned d value (R that should the variation phase _BeginningValue), just can calculate the c value of this variation phase based on aforementioned specific linear function or quadratic function expression formula, determine the aforementioned expression formula of this linear function or quadratic function thus, these all are that those skilled in the art are easy to realize.

After described expression formula is determined, in its corresponding variation phase, regulate described mol ratio R as Changing Pattern with this expression formula, just can implement the inventive method.Described adjusting can manually realize or computer program-control is realized, not special restriction.

According to the present invention, the Changing Pattern of described mol ratio R is not limited to the aforementioned specific linear function or the expression formula of quadratic function, also can be other forms of linear function or the nonlinear function that meets the present invention's regulation, and also can obtain aforementioned effect of the present invention equally.And those skilled in the art obviously can not give unnecessary details at this based on determining the expression formula of described other forms of linear function or nonlinear function with aforementioned similar calculation procedure.

Clearly, the R of previous variation phase _EventuallyValue is the R of next variation phase _BeginningValue.In addition, all aforementioned these R _EventuallyValue and R _BeginningValue all is selected from before the present invention aforementioned numerical range and the aforementioned preferred value scope at mol ratio R defined independently of one another.

The most preferred embodiment according to the present invention, in the whole growth of described polysilicon in the cycle, described ratio Q/R and described air input Q and described mol ratio R change and synchronism stability synchronously, wherein said air input Q and described mol ratio R also change and synchronism stability synchronously, and described air input Q and described mol ratio R (are changing in the phase arbitrarily with aforementioned specific linear function expression formula or quadratic function expression formula respectively at this moment, y=x) be Changing Pattern, regulate operation thereby simplified greatly.

In this case, the q/r value by making the next variation phase guarantees simultaneously that greater than a last q/r value that changes the phase described q/r value always is not less than 1, can implement the present invention easily.

In a specific embodiment, such as can implementing the present invention, but be not limited to this according to following step (Q and R are changed synchronously and stable, and cause ratio Q/R also to increase synchronously and stablize).

1) according to the growth cycle T (being made as 60 hours) of polysilicon and the accessibility of producing, Δ is determined on non-specially property ground _BecomeAnd Δ _SurelyNumber be respectively 3 and 2, and with Δ _SurelyOnly be located at the head and the tail of described growth cycle;

2) according to the accessibility and the practical situation of producing, with 3 Δs _BecomeWith 2 Δs _SurelyLength and order occurs and be set at as follows respectively non-specificly:

Manufacture method begins → Δ _{Steady 1}(5 hours) → Δ _{Become 1}(10 hours) → Δ _{Become 2}(15 hours) → Δ _{Become 3}(20 hours) → Δ _{Steady 2}(10 hours) → manufacture method finishes;

3), air input Q and the mol ratio R of manufacture method zero hour is set at Q respectively non-specificly according to the practical situation of producing ₀And R ₀(Q ₀=80Nm ³/ h, R ₀=8), this moment Q ₀/ R ₀=10, air input Q and the mol ratio R of manufacture method finish time is set at 30Q respectively non-specificly ₀And 3.5R ₀(Q/R=85.7);

4) according to the accessibility and the practical situation of producing, air input Q and mol ratio R non-specific ground in each variation phase changes (Q wherein in the following manner _Beginning(R _Beginning) and Q _Eventually(R _Eventually) represent beginning during each respectively and the Q value (R value) when finishing):

Manufacture method begins (Q _Beginning=Q ₀, R _Beginning=R ₀, and Q _Beginning/ R _Beginning=10);

Δ _{Steady 1}(Q _Beginning=Q ₀, R _Beginning=R ₀, and Q _Beginning/ R _Beginning=10; Q _Eventually=Q ₀, R _Eventually=R ₀, and Q _Eventually/ R _Eventually=10);

Δ _{Become 1}(Q _Beginning=Q ₀, R _Beginning=R ₀, and Q _Beginning/ R _Beginning=10; Q _Eventually=2Q ₀, R _Eventually=0.8R ₀, and Q _Eventually/ R _Eventually=25);

Δ _{Become 2}(Q _Beginning=2Q ₀, R _Beginning=0.8R ₀, and Q _Beginning/ R _Beginning=25; Q _Eventually=4Q ₀, R _Eventually=R ₀, and Q _Eventually/ R _Eventually=40);

Δ _{Become 3}(Q _Beginning=4Q ₀, R _Beginning=R ₀, and Q _Beginning/ R _Beginning=40; Q _Eventually=30Q ₀, R _Eventually=3.5R ₀, and Q _Eventually/ R _Eventually=85.7);

Δ _{Steady 2}(Q _Beginning=30Q ₀, R _Beginning=3.5R ₀, and Q _Beginning/ R _Beginning=85.7; Q _Eventually=30Q ₀, R _Eventually=3.5R ₀, and Q _Eventually/ R _Eventually=85.7); With

Manufacture method finishes (Q _Eventually=30Q ₀, R _Eventually=3.5R ₀, and Q _Eventually/ R _Eventually=85.7).

Wherein, in aforementioned each variation phase, determine the value of corresponding a, b, c and d according to the aforesaid calculation procedure of the present invention, obtain aforementioned at Q and specific linear function expression formula or the quadratic function expression formula of R, and make Q and R in this variation phase, change (can control automatically or time variable control by computer in case of necessity) continuously as Changing Pattern with this expression formula, can implement manufacture method of the present invention.

Shown in following embodiment, manufacturing method according to the invention, can when keeping higher polysilicon deposition speed, improve the output of the once through yield and the interior polysilicon of unit growth cycle of product polysilicon, reduce the unit cost of production of polysilicon thus.In addition, manufacturing method according to the invention owing to improved the utilization ratio of raw material silicon-containing compound such as trichlorosilane, can reduce the production of by-products amount, thereby reduced the load of subsequent disposal operation, and helped finally reducing the comprehensive production cost of polysilicon.

In addition, shown in following embodiment, manufacturing method according to the invention, by strengthening the turbulent flows of mixed raw material gas air inlet, reduce or eliminated effect of boundary layer, make polysilicon grain can with fine and close, form deposit on silicon rod uniformly, has improved the texture quality on silicon rod (especially silicon rod top) thus, and make configuration of surface obviously improve (the puffed rice phenomenon significantly reduces, especially near the crossbeam of silicon rod).

Embodiment

Following examples are to further specify of the present invention, rather than restriction the present invention.

In following all embodiment and comparative example, the reduction furnace 1 that has all used structure such as Fig. 1 institute summary to represent.

The volume of this reduction furnace 1 is 6m ³, the diameter of described silicon plug is 8mm, weight is 7 kilograms, and is preheated to 1100 ℃ before carrying out reduction reaction, use trichlorosilane (purity is 99%) as described silicon-containing gas, and the purity of described hydrogen is 99%.

In accordance with the following methods method for manufacturing polycrystalline silicon of the present invention is estimated.

(1) polysilicon output

Calculate the raising rate of polysilicon output by following calculating formula.

The raising rate (%) of polysilicon output=(silicon rod weight-silicon plug weight that embodiment obtains)/(silicon rod weight-silicon plug weight that comparative example obtains)

(2) polysilicon once through yield

Polysilicon once through yield (%)=silicon rod weight (kg)/[trichlorosilane consumption (kg) * 28/135.45]

The raising rate (%) of polysilicon once through yield=(the polysilicon once through yield of polysilicon once through yield-comparative example of embodiment)/(the polysilicon once through yield of comparative example)

(3) silicon rod texture quality

Block the silicon rod that is obtained along dotted line B-B shown in Figure 1, the structural state in this cross section of visual inspection.

When having the loose situation of structure interlayer or crystal grain on the cross section, be evaluated as *; On the contrary, whole cross section all shows as fine and close and uniform structure and tissue, then is evaluated as zero.

(4) silicon rod condition of surface

The condition of surface on the top of the silicon rod that visual inspection obtained.

When having the situation of macroscopic irregularitys such as puffed rice on the surface, be evaluated as *; On the contrary, surface texturisation does not evenly have obvious macroscopic irregularity, then is evaluated as zero.

Embodiment 1

In the present embodiment, the reaction pressure in the reduction furnace is controlled at 0.3MPa, and temperature of reaction is controlled at 1080 ℃.

When the beginning of manufacture method (0 constantly), the mixed gas that will be made of hydrogen and trichlorosilane (mol ratio R is 3.5) is with 42.5Nm ³The air input Q of/h feeds in the reduction furnace continuously.At this moment, described Q/R ratio is 12.14.

At first, be changed to 663.8Nm with 40 hours the described air input Q of time chien shih continuously with aforementioned quadratic function expression formula (wherein a value of this quadratic function expression formula and b value are determined by aforesaid account form in to specifications, and be in this omission, as follows) ³/ h, synchronous therewith, make described mol ratio R be changed to 5.7 continuously with aforementioned quadratic function expression formula (wherein the c value of this quadratic function expression formula and d value are determined by aforesaid account form in to specifications, and be in this omission, as follows).The result is to increase to 116.4 gradually with the described Q/R ratio of 40 hours time chien shih.

Secondly, keep this mol ratio R and this air input Q constant, keep described Q/R ratio 116.4 constant thus, make described reduction reaction proceed 5 hours.

Successively, be changed to 907.6Nm with 25 hours the described air input Q of time chien shih continuously with another aforementioned quadratic function expression formula ³/ h, synchronous therewith, make described mol ratio R be changed to 6.22 continuously with another aforementioned quadratic function expression formula.The result is to increase to 146 gradually with the described Q/R ratio of 25 hours time chien shih.

Once more, keep this mol ratio R and this air input Q constant, keep described Q/R ratio 146 constant thus, make described reduction reaction proceed 10 hours.

Subsequently, increase to 1310Nm with the described air input Q LINEAR CONTINUOUS of 15 hours time chien shih ³/ h, synchronous therewith, make described mol ratio R LINEAR CONTINUOUS increase to 7.The result is to increase to 187 gradually with the described Q/R ratio of 15 hours time chien shih.

At last, keep this mol ratio R and this air input Q constant, keep described Q/R ratio 187 constant thus, make described reduction reaction proceed 15 hours.Finish reaction.

This reaction is common goes into mixed gas 77670Nm ³, trichlorosilane 66113.5kg wherein.

After reaction finished, the weight of the polycrystalline silicon rod that weighing obtained was 1322.5 kilograms.

The once through yield of polysilicon=(1322.5-7) * 100%/(66113.5 * 28/135.45)=9.63%.

Comparative example 1

Compare with embodiment 1, reaction duration, total air input, trichlorosilane feeding amount always are all identical, i.e. and when the beginning of manufacture method (0 constantly), the mixed gas that will be made of hydrogen and trichlorosilane (mol ratio R is 6.1) is with 706Nm ³The air input Q of/h feeds in the reduction furnace continuously, and at this moment, described Q/R ratio is 115.7.And keep air input Q, the mol ratio R of described mixed gas all constant, and it is 115.7 constant keeping described Q/R ratio thus, operation 110h is until the end of polysilicon manufacturing reaction.

After reaction finished, the weight of the polycrystalline silicon rod that weighing obtained was 1147.5 kilograms.

The polysilicon once through yield=(1147.5-7) * 100%/(66113.5 * 28/135.45)=8.35%.

Based on the polycrystalline silicon rod weight data and the polysilicon once through yield data of embodiment 1 and comparative example 1 acquisition, calculate the raising rate of polysilicon output and the raising rate of polysilicon once through yield, and show the result in the following table 1.

Other evaluation results to the polycrystalline silicon rod of acquisition in embodiment 1 and the comparative example 1 also are summarized in the following table 1 in the lump.

Embodiment 2

When the beginning of manufacture method (0 constantly), the mixed gas that will be made of hydrogen and trichlorosilane (mol ratio R is 3) is with 60Nm ³The air input Q of/h feeds in the reduction furnace continuously.At this moment, described Q/R ratio is 20.

Then, be changed to 1145.6Nm with 60 hours the described air input Q of time chien shih continuously with aforementioned quadratic function expression formula ³/ h, synchronous therewith, make described mol ratio R be changed to 5 continuously with aforementioned quadratic function expression formula.The result is to increase to 229 gradually with the described Q/R ratio of 60 hours time chien shih.

Then, keep this mol ratio R and this air input Q constant, keep described Q/R ratio constant thus, make described reduction reaction proceed 15 hours, finish the manufacturing reaction of polysilicon.

This reaction was carried out 75 hours altogether, fed mixed gas 39664Nm ³, trichlorosilane 43337.5kg wherein.

After reaction finished, the weight of the polycrystalline silicon rod that weighing obtained was 834 kilograms.

The once through yield of polysilicon=(834-7) * 100%/(43337.5 * 28/135.45)=9.24%.

Comparative example 2

Compare with embodiment 2, reaction duration, total air input, trichlorosilane feeding amount always are all identical, i.e. and when the beginning of manufacture method (0 constantly), the mixed gas that will be made of hydrogen and trichlorosilane (mol ratio R is 4.5) is with 528Nm ³The air input Q of/h feeds in the reduction furnace continuously, and at this moment, described Q/R ratio is 117.And keep air input Q, the mol ratio R of described mixed gas all constant, and it is 117 constant keeping described Q/R ratio thus, operation 75h is until the end of polysilicon manufacturing reaction.

After reaction finished, the weight of the polycrystalline silicon rod that weighing obtained was 634.5 kilograms.

The polysilicon once through yield=(634.5-7) * 100%/(43337.5 * 28/135.45)=7.01%.

Based on the polycrystalline silicon rod weight data and the polysilicon once through yield data of embodiment 2 and comparative example 2 acquisitions, calculate the raising rate of polysilicon output and the raising rate of polysilicon once through yield, and show the result in the following table 1.

Other evaluation results to the polycrystalline silicon rod of acquisition in embodiment 2 and the comparative example 2 also are summarized in the following table 1 in the lump.

Embodiment 3

In the present embodiment, the reaction pressure in the reduction furnace is controlled at 0.35MPa, and temperature of reaction is controlled at 1100 ℃.

When the beginning of manufacture method (0 constantly), the mixed gas that will be made of hydrogen and trichlorosilane (mol ratio R is 4) is with 114.5Nm ³The air input Q of/h feeds in the reduction furnace continuously.At this moment, described Q/R ratio is 28.6.

The described air input Q of time chien shih with 30 hours is changed to 557Nm continuously with aforementioned quadratic function expression formula ³/ h, synchronous therewith, make described mol ratio R be changed to 6 continuously with aforementioned quadratic function expression formula, the result is to increase to 92.8 gradually with the described Q/R ratio of 30 hours time chien shih, the end reaction.This reaction is common goes into mixed gas 8662Nm ³, trichlorosilane 8740.7kg wherein.

After reaction finished, the weight of the polycrystalline silicon rod that weighing obtained was 179 kilograms.

The once through yield of polysilicon=(179-7) * 100%/(8740.7 * 28/135.45)=9.52%.

Comparative example 3

Compare with embodiment 3, reaction duration, total air input, trichlorosilane feeding amount always are all identical, i.e. and when the beginning of manufacture method (0 constantly), the mixed gas that will be made of hydrogen and trichlorosilane (mol ratio R is 5) is with 288.7Nm ³The air input Q of/h feeds in the reduction furnace continuously, and at this moment, described Q/R ratio is 57.74.And keep air input Q, the mol ratio R of described mixed gas all constant, and it is 57.74 constant keeping described Q/R ratio thus, operation 30h is until the end of polysilicon manufacturing reaction.

After reaction finished, the weight of the polycrystalline silicon rod that weighing obtained was 121.5 kilograms.

The polysilicon once through yield=(121.5-7) * 100%/(8740.7 * 28/135.45)=6.34%.

Based on the polycrystalline silicon rod weight data and the polysilicon once through yield data of embodiment 3 and comparative example 3 acquisitions, calculate the raising rate of polysilicon output and the raising rate of polysilicon once through yield, and show the result in the following table 1.

Other evaluation results to the polycrystalline silicon rod of acquisition in embodiment 3 and the comparative example 3 also are summarized in the following table 1 in the lump.

Table 1

In addition, the cross-section photograph figure (silicon rod section of beam photo figure) that Fig. 2 is the silicon rod made of embodiment 1 when dotted line B-B shown in Figure 1 blocks, and Fig. 3 is the photo figure of the condition of surface of the silicon rod made according to embodiment 1.

Although the specific embodiment of the present invention has been given to describe in detail and explanation above with reference to accompanying drawing; but should indicatedly be; those skilled in the art can carry out various equivalences to above-mentioned embodiment according to conception of the present invention and change and modification; when the function that it produced does not exceed spiritual that specification sheets contains yet, all should be within protection scope of the present invention.

Claims

1. method of making polysilicon, it is by feeding continuously the mixed gas that is made of hydrogen and silicon-containing gas as the raw material air inlet in reduction reactor, in described reduction reactor, utilize the described silicon-containing gas of described hydrogen reducing, make the method for polysilicon thus, it is characterized in that, may further comprise the steps:

Q _t1/R _t1≥Q _t2/R _t2

2. the method for claim 1 is characterized in that, has at least one t3 constantly in the process of described manufacture method, and described ratio Q/R satisfies following relational expression,

Q _t1/R _t1＞Q _t3/R _t3

3. method as claimed in claim 1 or 2 is characterized in that described silicon-containing gas is a chlorosilane.

4. method as claimed in claim 3 is characterized in that, described chlorosilane is trichlorosilane or silicon tetrachloride, or any mixture of the two.

5. the method for claim 1 is characterized in that, described R _T1With described R _T2Identical or different, be selected from 1.8-40 independently of one another.

6. method as claimed in claim 5 is characterized in that, described R _T1With described R _T2Identical or different, be selected from 3-30 independently of one another.

7. method as claimed in claim 6 is characterized in that, described R _T1With described R _T2Identical or different, be selected from 3.2-20 independently of one another.

8. the method for claim 1 is characterized in that, described Q _T1With described Q _T2Identical or different, be selected from 20～3000Nm independently of one another ³/ h.

9. method as claimed in claim 8 is characterized in that, described Q _T1With described Q _T2Identical or different, be selected from 50～2500Nm independently of one another ³/ h.

10. the method for claim 1 is characterized in that, described Q _T1/ R _T1With described Q _T2/ R _T2Be selected from 5～400 independently of one another.

11. method as claimed in claim 10 is characterized in that, described Q _T1/ R _T1With described Q _T2/ R _T2Be selected from 10～350 independently of one another.

12. method as claimed in claim 11 is characterized in that, described Q _T1/ R _T1With described Q _T2/ R _T2Be selected from 12～300 independently of one another.

13. method as claimed in claim 2 is characterized in that, described R _T1, described R _T2With described R _T3Identical or different, be selected from 1.8-40 independently of one another.

14. method as claimed in claim 13 is characterized in that, described R _T1, described R _T2With described R _T3Identical or different, be selected from 3-30 independently of one another.

15. method as claimed in claim 14 is characterized in that, described R _T1, described R _T2With described R _T3Identical or different, be selected from 3.2-20 independently of one another.

16. method as claimed in claim 2 is characterized in that, described Q _T1, described Q _T2With described Q _T3Identical or different, be selected from 20～3000Nm independently of one another ³/ h.

17. method as claimed in claim 16 is characterized in that, described Q _T1, described Q _T2With described Q _T3Identical or different, be selected from 50～2500Nm independently of one another ³/ h.

18. method as claimed in claim 2 is characterized in that, described Q _T1/ R _T1, described Q _T2/ R _T2With described Q _T3/ R _T3Be selected from 5～400 independently of one another.

19. method as claimed in claim 18 is characterized in that, described Q _T1/ R _T1, described Q _T2/ R _T2With described Q _T3/ R _T3Be selected from 10～350 independently of one another.

20. method as claimed in claim 19 is characterized in that, described Q _T1/ R _T1, described Q _T2/ R _T2With described Q _T3/ R _T3Be selected from 12～300 independently of one another.