CN1204298A - Process and apparatus for preparing polycrystalline silicon and process for preparing silicon substrate for solar ceu - Google Patents
Process and apparatus for preparing polycrystalline silicon and process for preparing silicon substrate for solar ceu Download PDFInfo
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Abstract
A process and an apparatus which enable mass production of polycrystalline silicon and a substrate made therefrom at a low cost from metallic silicon or silicon oxide as a starting material in a flow production line involving a series of continuous steps. The polycrystalline silicon and the silicon substrate for solar cells are prepared from metallic silicon through step A of refining metallic silicon under redudced pressure and solidifying the metallic silicon to remove impurities from the molten metal, thereby preparing an ingot; step B of cutting and removing an impurity-enriched portion of the ingot; step C of remelting the residue and removing boron and carbon by oxidation from the molten metal under an oxidizing atmosphere, followed by blowing of a gaseous mixture of argon with hydrogen to conduct deoxidation, step D of casting the molten metal after the deoxidation into a mold to conduct unidirectional solidification, thereby preparing an ingot;
Description
Technical field
The present invention relates to the manufacture method of the manufacturing method and apparatus and the silicon for solar cell substrate of polysilicon, especially relating to a kind of is starting raw material with Pure Silicon Metal or silicon oxide, makes production technology as the polycrystalline silicon used for solar battery substrate of end article by the streamline operration of series of processes.
Background technology
Research about the solar cell aspect has been carried out for a long time, has occurred its photoelectric transformation efficiency under a kind of sunlight on the ground recently and has reached solar cell about 13～15%, and progressively reached practicability aspect the various different purposes.Yet,, still not talkative very universal in China at least as the energy of aspects such as general home-use electric power or automobile, boats and ships, work mechanism.Its reason is that still mass production is used to make the necessary silicon substrate technology of solar cell less than setting up at an easy rate so far.
Now, in order to make the silicon substrate of used for solar batteries, use the chemical process can be, directly make and be suitable as semi-conductor and use and become blocky high purity silicon with the low Pure Silicon Metal of material purity (Si of 99.5 weight %) as starting raw material.And then use metallurgical method will this blocky high purity silicon fusion and its adjustment become the chemical constitution that is suitable for solar cell again, with drawing or directional solidification method the melt that is obtained is made silicon ingot then, at last this silicon ingot is cut into (slice) thin slice.That is to say, as shown in Figure 5, at first with Pure Silicon Metal and hydrochloric acid reaction, be gasificated into trichlorosilane, by this gas rectifying being removed impurity wherein, make itself and hydrogen reaction then, make it separate out highly purified silicon according to so-called CVD (chemical vapour deposition) method by gas.Therefore, the bonding force that the high purity silicon that is obtained only becomes between a kind of crystalline particle is very weak, only the aggregate of being made up of the silicon particle.In addition, even contained boron is reduced to about 0.001ppm in the high purity silicon that forms this aggregate, can not satisfy as the desired specification requirement of substrate of P-N-type semiconductorN than resistance 0.5～1.5 Ω cm.For above-mentioned HIGH-PURITY SILICON is used for solar cell, must adjust it than resistance and control its crystallinity, so that obtain monocrystalline or have the crystallization of the above particle diameter of several mm, and make its crystal boundary can not produce detrimentally affect to photoelectric transformation efficiency, therefore, above-mentioned HIGH-PURITY SILICON can not directly be made substrate under this state.Then, shown in the right side of Fig. 5, also must experience with the fusion again of this block, bath composition is adjusted (interpolation boron), ingot barization (monocrystalline is adopted drawing, polycrystalline is adopted directional solidification method) and is formed the operation of substrate.
Yet, said manufacture method in the past also must be able to be applicable to that semi-conductive high purity silicon ingot carries out composition adjustment (mainly being to add boron) and refining once more to those, so that make it be applicable to solar cell, complex technical process so not only, qualification rate is low, but also need the equipment of fusing again and the energy that adds, so manufacturing cost height.Therefore, as above-mentioned, the solar cell that can buy all is the product of high price now, and this just becomes the obstacle that hinders its acquisition extensively to popularize.In addition, according to chemical process, reach high purity in order to make Pure Silicon Metal, can't produce the material of contaminate environment such as a large amount of silane, muriate with avoiding, becoming holds it back reaches mass-produced obstacle, and therefore problem is also arranged.In addition, owing to be subjected to the influence of above-mentioned manufacture method, nearest disclosed technical study trend is that manufacturing process is segmented more, for example the high purifying of Pure Silicon Metal and solidification technology etc.
For example, that Te Kaiping 5-139713 communique discloses is a kind of " obtaining the method for the silicon of low boron content; this method is to be to keep fused silicon in the container of principal constituent by silicon-dioxide or with silicon-dioxide at one; spray a kind of plasma gas jet of rare gas element on the surface of this melt, the bottom from this container is blown into rare gas element simultaneously ".In addition, the spy opens flat 7-17704 communique and discloses that a kind of " remove the method for boron expeditiously, this method is when using electron beam to come deposite metal silicon, on the surface of metallic silicon power, with respect to every 1kg silicon, is pre-formed the SiO of 1.5～15kg
2".In addition, about solidification technology, the spy opens clear 61-141612 communique and has proposed a kind of " prevent to separate out in silicon ingot the technology of inclusion, this technology is to make this mold rotation when being molded into fused silicon in the mold ".In addition, the applicant oneself also is willing to propose in flat 7-29500 number (applying date is for putting down on February 17th, 7) a kind of " carrying out the purified method by making molten metal silicon carry out directional freeze " the spy.
On the other hand, the technology of directly making silicon for solar cell by Pure Silicon Metal is not have.For example, the spy opens clear 62-252393 communique and discloses a kind of zone melting process (Zonemelting), this method be useless silicon with a kind of electronic industry of once using as semi-conductor as starting raw material, the plasma jet that uses the gas mixture of argon, hydrogen and oxygen to produce carries out zone melting with said raw material to be handled.Yet this method is a kind of method of utilizing industrial waste, can not become a kind of mainstream technology that needs the mass production silicon substrate.In addition, though raw silicon uses economy, in case require high purityization, then this method just can not become the replacement technology of the manufacture method of above-mentioned trouble.In addition, the spy open clear 63-218506 communique disclose a kind of by plasma fusion by Powdered, particulate state or make the method for the bulk silicon that used for solar batteries or electronic machine use without the Pure Silicon Metal of grinding.Yet it is identical that the principle of this method and above-mentioned spy open clear 62-252393 communique, all is to use the zone melting process of plasma body, exists power consumption big and can not mass-produced shortcoming.In addition, the embodiment of this communique is only by the bar-like silicon about laboratory scale acquisition 50g, for then not record of the silicon for solar cell substrate that reaches practical size.
Disclosure of an invention
In view of the foregoing, the purpose of this invention is to provide a kind of by Pure Silicon Metal or silicon oxide as starting raw material, carry out streamline operration by a series of series-operation, cheap and produce as the polysilicon of goods in large quantities and use the manufacturing method and apparatus of the substrate that this polysilicon makes.
The present inventor without chemical process, only utilizes metallurgical method in order to achieve the above object, is conceived to obtain maximum economical effectiveness and has carried out deep research, thereby finished the present invention.
That is to say, the invention provides a kind of manufacture method of polysilicon, it is characterized in that, use following each operation to make polysilicon by Pure Silicon Metal:
A. with Pure Silicon Metal fusion in a vacuum, make phosphorus gasification volatilization wherein and it is removed, solidify then from melt, removing impurity component, thereby obtain ingot bar;
B. the part excision of the impurity of above-mentioned ingot bar being concentrated;
C. the remainder after the part that impurity the concentrated excision melts again, then in oxidizing atmosphere with boron and carbon oxidation from melt remove, then be blown into the gas mixture of argon gas or argon and hydrogen to carry out deoxidation to this melt;
D. the melt after the above-mentioned deoxidation is molded in the mold, carries out directional freeze, obtain ingot bar;
E. the part excision of concentrating of the impurity of the ingot bar that obtains by directional freeze.
In addition, the present invention also provides a kind of manufacture method of polysilicon, it is characterized in that, the reduction refining by silicon oxide obtains above-mentioned Pure Silicon Metal.
In addition, the present invention also provides a kind of manufacture method of polysilicon, it is characterized in that, at first the Pure Silicon Metal of the molten state that obtains by the silicon oxide refining is transferred in the crucible, oxidation solidifies it after removing boron and carbon in oxidizing atmosphere, then carry out the B operation of claim 1, carry out fusion in a vacuum, carry out C, D and the E operation of claim 1 then.
In addition, the present invention also provides a kind of manufacture method of polysilicon, it is characterized in that, above-mentioned oxidizing atmosphere is by H
2O, CO
2Or O
2Gas forms, and its consumption is the least possible to carry out the method for local heating and remove the silicon oxide that generates on the surface of above-mentioned melt so that the not oxidized silicon in the interface of above-mentioned melt and gas covers with plasma arc, perhaps use H
2O, CO
2Or O
2Air-blowing goes in the melt to replace above-mentioned in oxidizing atmosphere.
In addition, the present invention also provides a kind of manufacture method of polysilicon, it is characterized in that, uses SiO
2Or Si
3N
4As above-mentioned releasing agent, freezing interface translational speed when solidifying in order to remove above-mentioned impurity is below 5mm/min, freezing interface translational speed when carrying out directional freeze is perhaps cut off above-mentioned ingot bar from this ingot bar lower end height more than 70% below 2mm/min.
In addition, the present invention also provides a kind of manufacture method of polysilicon, it is characterized in that, the phosphorus concentration in the said melt is reduced to below the 0.3ppm, and boron concentration is reduced to below the 0.6ppm or with carbon concentration and is reduced to below the 10ppm.
Also finished the present invention aspect manufacturing installation, just a kind of manufacturing installation of polysilicon is characterized in that, this device comprises: be used to melt or the heating unit of heating of metal silicon; Be used to keep the maintenance container of molten metal silicon; The 1st mold of the melt in this maintenance container is used to cast; Surround these and keep container and mold, be used for making phosphorus from underpressure chamber that the melt gasification is removed; Be used for to take from the melting appartus again that the part of the ingot bar of above-mentioned mold melts or heats; Be used to keep the refining vessel of the melt that melts again; The melt that is used in this refining vessel is blown into or jet paraffin oxidation gas, hydrogen or hydrogen-argon-mixed nozzle; Be used for the melt of deoxidation is cast into the 2nd mold of ingot bar.
In addition, the invention provides a kind of manufacturing installation of polysilicon, it is characterized in that, the vacuum tightness in the above-mentioned underpressure chamber is higher than 10
-3Holder, by water-cooling jacket crucible made of copper or plumbago crucible as above-mentioned maintenance container, by SiO
2Matter crucible, SiO
2Mold pressing crucible or SiO
2The lining crucible is as above-mentioned refining vessel.
In addition, the invention provides a kind of manufacturing installation of polysilicon, it is characterized in that, above-mentioned heating unit is that electron beam gun, above-mentioned melting appartus again are plasma arc rifle or direct current arc source.
In addition, the invention provides a kind of manufacturing installation of polysilicon, it is characterized in that, the sidewall of the 1st and the 2nd mold is formed by lagging material, its bottom is formed by water-cooling jacket, and configuration is used to heat the heating source that is cast into melt above these molds, and the ratio of the height H that makes above-mentioned mold and its diameter W is W/H＞0.5.
In addition, main aspect of the present invention provides a kind of manufacture method of silicon for solar cell substrate, it is characterized in that, the polysilicon ingot bar that above-mentioned any manufacture method is obtained cuts into the thin plate that thickness is 100～450 μ m.
According to the present invention, use above-mentioned method and device to make polysilicon or silicon for solar cell substrate, do not need to carry out in method in the past the composition set-up procedure of indispensable HIGH-PURITY SILICON.In addition, not only can reduce the useless consumption of energy, and, therefore can not produce the material that resembles peculiar contaminate environment when using chemical process in large quantities, thereby can realize the maximization of equipment relievedly owing to only adopt metallurgical method.Its result can provide a kind of photoelectric transformation efficiency good silicon for solar cell substrate according to the price more much lower than the past.And, even do not make substrate by the polysilicon of implementing the present invention's acquisition, also can be effectively as other purposes such as iron-making raw materials.
As mentioned above, according to the present invention, can avoid the waste of energy, and can make equipment enlarging, therefore more excellent polysilicon and the polycrystalline silicon used for solar battery substrate of production purity in large quantities.Its result can provide a kind of photoelectric conversion efficient on the ground not have what different polycrystalline silicon used for solar battery substrate with the product that method obtained by the past by low especially price, can expect that therefore solar cell obtains to popularize widely.In addition, even the polysilicon that is obtained is not used in the manufacturing substrate, can also be used as iron-making raw material etc. effectively.
Simple declaration to accompanying drawing
Fig. 1 is the schema of one of the manufacture method of said polysilicon and silicon for solar cell substrate among expression the present invention example.
Fig. 2 is the another kind of scheme schema of the manufacture method of said polysilicon and silicon for solar cell substrate among an expression the present invention.
Fig. 3 is a device mode chart that is used for implementing said polysilicon of the present invention and silicon for solar cell substrate manufacture method.
Fig. 4 is a device that is used for implementing said polysilicon of the present invention and the another kind of scheme of silicon for solar cell substrate manufacture method.
Fig. 5 is the schema of the manufacture method of expression silicon for solar cell substrate in the past.
The preferred plan that carries out an invention
One of the manufacture method example (wherein being the manufacturing of substrate by the part of dotted line) of said polysilicon and silicon for solar cell substrate among the present invention is shown with a flow chart in Fig. 1.
At first the metallic silicon of a kind of purity lower (99.5 % by weight Si) is packed in a graphite or the water-cooled maintenance container made of copper, under vacuum, carry out melting. At this moment, as heater means, can utilize known gas-heated, electrical heating etc., but electron gun preferably. Herein, with the metallic silicon (hereinafter referred to as melt) of melting in above-mentioned maintenance container, keep predetermined time (for example 30～60 minutes) 1450～1900 ℃ temperature ranges, so that so that (vacuum refining) removed in the phosphorus in the impurities and aluminium gasification. Preferably the phosphorus concentration in the melt is reduced to below the 0.3ppm. Then for the impurity such as Fe, Al, Ti, Ca are reduced to below the 100ppm, this melt is molded in the 1st mold, makes its cooling, thereby melt is solidified upward from the bottom, the translational speed of freezing interface is 5mm/min. Its result has obtained the ingot bar that melt that above-mentioned impurity element concentrates in the end solidifies.
About 30% excision in the top of the above-mentioned ingot bar that then, impurity element is concentrated. Then remaining ingot bar is packed into one and it is melted in the melting furnace with plasma arc again. In the case, heater means is not limited to plasma-arc. Melt after the fusing is warming up to the temperature more than 1450 ℃ and makes simultaneously it and the oxidizing gas reaction, thereby the boron in the melt and carbon are removed (refinement oxide) with the form of oxide. Then, blow and spray into argon gas or argon hydrogen gaseous mixture certain hour in the melt after finishing to refinement oxide. Its result so that the oxygen in this melt be removed to below the 10ppm. Above-mentioned refinement oxide can be carried out in the pressure-reducing chamber, also can carry out in atmosphere. Then the melt after this deoxidation is molded in the 2nd mold that scribbles releasing agent as refining product, it is directionally solidified, thereby obtain ingot bar. Therefore the impurity element that concentrated on the top of this ingot bar cuts off this part (usually accounting for about 20%) and removes, and remainder is as the polysilicon goods.
The above has described the manufacture method of polysilicon, but in the situation that will make the silicon for solar cell substrate, it is the thin slice of 100～450 μ m that said remainder is cut (sheet) one-tenth thickness with a kind of multi-wire saw.
Because above-mentioned metallic silicon as initiation material can obtain by the reduction refining of silica usually, therefore, when also belong to the present invention during as initial substance with silica. For the method for refining of silica, for obtain with the invention described above in the product of the initial metallic silicon that uses with par purity, can use any known method. For example, can use a kind of buried arc melting furnace, make the method for silica fusing, reduction with carbon as reducing agent. In addition, according to the present invention, when preparing metallic silicon by silica, also can consider removing in advance as polysilicon or the unwanted composition of silicon for solar cell substrate. That is to say that shown in the flow chart of Fig. 2, what obtained by silica, purity metallic silicon lower and that be in molten condition is packed in the refining vessel (for example crucible), the method for carrying out so-called preliminary refining. Specifically, be blown into oxidizing gas (H in the melt in the crucible2O、CO
2Deng), boron and carbon are removed as oxide, it is solidified. Then the ingot bar that obtains is melted in above-mentioned pressure-reducing chamber with vacuum refining so that then its dephosphorization carries out directional solidification, thus the ingot bar of acquisition polysilicon. In order to obtain substrate, can similarly ingot bar be thinly sliced with above-mentioned. The advantage of the method is by changing the part of common metal silicon manufacturing operation, not needing " taking off boron, decarburization " and the step of " solidifying in order to remove impurity " of the invention described above. Its result can save some equipment and fall significantly low-energy consumption, polysilicon and the silicon for solar cell substrate that therefore can have same level by the product that lower cost obtains and obtains according to the said method of the invention described above. Take off boron and decarburization operation if especially finished in advance at the scene, mine in the fabrication stage of metallic silicon, for the manufacturer of polysilicon or substrate, the operation of back just is very easy to carry out so.
In passing explanation, freezing interface translational speed in the present invention, be below the 5mm/min when the 1st mold, be below the 2mm/min when the 2nd mold, its reason is, if greater than these numerical value, then impurity metallic elements the concentrating above ingot bar such as the Fe in the metallic silicon, Al are carried out fully not. In addition, why will cut off above-mentioned ingot bar by the At The Height more than 70% from this ingot bar lower end, this is for so that be lower than remainder of this height and can reach as the desired target of polysilicon and form. In addition, require in the present invention the vacuum in the above-mentioned pressure-reducing chamber to be higher than 10-3Holder, this is for the vapour pressure that makes phosphorus in silicon metal be suitable for the gasifying needs of dephosphorization.
In addition, in the present invention, the reason that the phosphorus concentration in the melt is reduced to below the 0.3ppm is can stably work in order to ensure solar cell; The reason that boron concentration is reduced to below the 0.6ppm is in order to make it be suitable as the substrate that P-type semiconductor is used; The reason that concentration of carbon is reduced to below the 10ppm is for the reduction that suppresses to separate out SiC in the silicon crystallization He prevent photoelectric transformation efficiency.
In addition, the maintenance container when using water-cooling jacket crucible made of copper or graphite crucible as above-mentioned metallic silicon fusing, and use SiO2Matter crucible, SiO2Pressing mold or SiO2The lining crucible is as above-mentioned refining vessel, and its reason is that therefore easy and other substance reactions of silicon, if use above-mentioned container in addition, will make these composition elements sneak in the silicon. In passing explanation when taking off the operation such as boron in the fabrication stage of metallic silicon, can be used SiO2The Al of cheapness in addition2O
3, MgO, graphite etc. be as the lining of refractory body. Its reason is, even for example sneaked into these impurity, removes in also can be follow-up the processing stage. In addition, use SiO2Or Si3N
4The mold releasing agent that uses when solidifying, its reason is the same. Must be when silicon its volumetric expansion 10% when solidifying of melting, to use releasing agent can prevent residual stress with the reason of releasing agent.
In addition, in device of the present invention, as shown in Figure 3, except when solidifying, the melt 2 of metallic silicon 1 almost is to flow into continuously in the follow-up step. According to the method, manufacturing operation is become smoothly, the operating time shortens, thereby makes manufacturing cost more cheap. In addition, the device that uses in the present invention is hopeful to reduce production costs by a large amount of productions owing to only based on metallurgical method, therefore can easily maximize, and can not produce the material of contaminated environment.
In order to remove boron and the carbon in the melt 2, as long as used oxidizing gas has weak oxidability, preferably use H2O or CO2 If oxidizing force is excessively strong, then can form SiO on the surface of melt2Film, thus removing of boron or carbon dioxide hindered. Therefore, in the case, in order to remove this film, must use plasma arc gun 4 or by direct-current arc source spray arc. In addition, above-mentioned oxidizing gas also can directly be blown in the melt. Material for the nozzle 5 that is blown into oxidizing gas is only limited to graphite or SiO2 If the material beyond using these two kinds then can cause the pollution to melt 2. In addition, for the ingot bar 6 that takes out from the 2nd mold 9 is cut into laminar cutting machine (not shown), it is comparatively ideal using known multi-wire saw or multitool blade saw. The reason that the thickness of thin slice is defined as 100～450 μ m is, if less than 100 μ m, then its intensity is excessively low, if surpass 450 μ m, then its photoelectric transformation efficiency reduces.
In device of the present invention, taked special design for the structure of the mold 9 that solidifies. Particularly as shown in Figure 3, its shape resembles a kind of so-called basin type, its diameter W to the ratio of height H more than 0.5. In addition, at its sidewall heat-barrier material 11 is set, in its bottom water-cooling jacket 10 is set, heating source 8 is set above it, in order to can adjust the translational speed of above-mentioned freezing interface.
In addition, in the present invention, in order to improve the purity of silicon, can carry out repeatedly separately (solidifying again and again fusing) to the operation of solidifying of in the 1st and the 2nd mold, carrying out repeatedly. In addition, can prepare many molds, above-mentioned maintenance container or refining vessel can be maximized simultaneously, the melt in these containers be divided inject said mold. In addition, in the present invention, the enforcement of above-mentioned operation A, B, C, D, E order, except D, E being placed at last, the order of other steps can be different.
Embodiment 1
As shown in Figure 3, the electron beam gun that it is 300KW that the top in underpressure chamber 18 has an output rating, Pure Silicon Metal 1 infeeded the middle fusing of maintenance container 19 (also claiming smelting furnace) of graphite system with 10kg/ hour speed.At this moment, make underpressure chamber 18 reach 10
-3The vacuum tightness of holder, the part of phosphorus and aluminium element gasifies from melt 2 and is removed.Then this solution 2 is poured in the water-cooled copper mold 9, so that it keeps molten state, makes its freezing interface translational speed begin upwards to solidify then, obtain the ingot bar 6 of 50kg from the bottom with 1mm/min with electron beam 3 irradiation bath surfaces.Top 20% (mark A) cut-out of this ingot bar 6 is removed, the chemical constitution of ingot bar has been shown in the table 1.Table 1 unit (ppm)
| B | P | Fe | Al | Ti | Ca | C | O | |
| | 7 | 23 | 980 | 860 | 180 | 950 | ～5000 | ?- |
| Ingot bar after thick the making with | 7 | ＜0.1 | 1?0 | 8.5 | 2 | 10 | 35 | ?- |
| Substrate | 0.1 | ＜0.1 | ＜0.1 | ＜0.1 | ＜0.1 | ＜0.1 | 3.5 | 5.7 |
Then the surplus part of cutting of this ingot bar 6 is placed a silicon oxide crucibles (refining vessel) 16, utilize a configuration above it, output rating is that the plasma arc rifle 4 of 100KW is with this ingot bar fusing.Temperature with this melt remains on 1600 ℃ then, blows a kind of mixed gas 21 that contains the argon-water vapor of 15 volume % water vapors of spray to the surface of this melt simultaneously.At this moment, from melt 2, materials, measure the ratio resistance of this sample.After through about 2 hours, become 1 Ω cm than resistance, at this moment replace mixed gas 21 and carry out 30 minutes deoxidation with simple argon gas.Then this melt is molded into one and scribbles releasing agent Si
3N
4Graphite system the 2nd mold in, it begun to cool down from the bottom and solidify, thereby obtain ingot bar.At this moment, utilize a graphite heater 8 that is installed in mold 9 tops to come the melt heating surface.The result makes that the translational speed of freezing interface is 0.7mm/min.
After solidifying end, with top 30% excision of acquisition ingot bar 6, with remainder as the polysilicon goods.Then use multi-thread saw with these goods thin slice that to cut into a kind of every thickness be 350 μ m, having obtained 300 chip sizes is the silicon for solar cell substrate of 15cm * 15cm.The performance of this substrate is as follows: than resistance is 1.2 Ω cm; The life-span of minority carrier is 12 microseconds; Photoelectric transformation efficiency is 13.8%.In addition, its chemical constitution is as shown in table 1.
Bottom 70% according to the ingot bar 6 that is obtained by the 1st mold with the same method of example 1 placed a silicon oxide crucibles (refining vessel) 16, utilize a configuration above it, output rating is that the plasma arc rifle 4 of 100KW is with this ingot bar fusing.Temperature with this melt 2 remains on 1600 ℃ then, by a porous plug 15 that is arranged on crucible 16 bottoms, with 10 liters/minute flows in melt 2, be blown into contain 15 volume % water vapors argon-water vapor mixture body 21 to take off boron and decarburization.Carry out deoxidation, directional freeze and excision operation then, obtain the goods of polysilicon, and similarly to Example 1 these goods are cut into slices, obtained the silicon for solar cell substrate.
The size of the substrate that obtains, sheet number and performance are all almost identical with embodiment 1.
In electric arc furnace shown in Figure 4 12, use carbonaceous reducing agent to make the molten metal silicon of chemical constitution as shown in table 2 as silicon oxide fusion, the reduction of initial substance.When discharging, pour the said Pure Silicon Metal 1 of 50kg into an inwall and be lined with the silicon-dioxide flame retardant coating, and be equipped with in the crucible 14 of porous plug 15 in its bottom, in melt, be blown into a kind of argon-water vapor mixture that contains 20 volume % water vapors 30 minutes by this porous plug 15 then.Because the heat of oxidation of silicon and the temperature of melt 2 is increased to 1650 ℃, thereby cause and take off boron and decarburizing reaction.This melt 2 is molded into one is furnished with SiC system well heater above it, and have in above-mentioned the 1st mold of bottom cooling system, cool off and solidify with the freezing interface translational speed of 1.5mm/min.Then packed into one in the bottom 80% of obtaining ingot bar be configured in the maintenance container in the above-mentioned underpressure chamber melt, dephosphorization and deoxidation, this melt is molded in above-mentioned the 2nd mold carries out directional freeze then.The ingot bar 6 that so obtains is excised 30% of its tops, and remaining part is as the goods of polysilicon.With a kind of multitool blade saw these goods are cut into the thin slice of above-mentioned size then, obtained 300 polycrystalline silicon used for solar battery substrates.The ratio resistance of this substrate is 0.9 Ω cm, and the life-span of minority carrier is 10 microseconds, and photoelectric transformation efficiency is 13.5%.In addition, its chemical constitution table 2 as shown in table 2 unit (ppm)
| B | P | Fe | Al | Ti | Ca | C | O | |
| Pure Silicon Metal in the crucible | 7 | 25 | 1010 | 800 | 180 | 950 | ～5000 | - |
| Ingot bar after the crucible refining | 7 | 23 | 10 | 25 | 3 | 13 | 6 | 40 |
| Substrate | 0.1 | ＜0.1 | ＜0.1 | ＜0.1 | ＜0.1 | ＜0.1 | 4 | 1 |
At last, the advantage and the prior art of the manufacture method of the manufacturing method and apparatus of polysilicon described in the invention described above and polycrystalline silicon used for solar battery substrate compared, and comparing result is summarized as follows.
That is to say, the manufacture method of the manufacture method of polysilicon described in the present invention and polycrystalline silicon used for solar battery substrate no problem aspect resource (the problem that there is lack of raw materials can not take place), do not produce the by product of contaminate environment in addition yet, the maximization and the mass production that can adapt to equipment as metallurgical technology basically, therefore, even the demand of solar cell reaches present hundreds of times, also can stably supply with required substrate.In addition, according to manufacture method in the past, making substrate by blocky high purity silicon will be through steps such as pulverizing, therefore to produce loss or substandard product about 20 weight %, but in the present invention, manufacturing by silicon is a successive integrated process until obtaining substrate, and therefore loss is few, can use power supply and energy effectively.Therefore, the silicon substrate price that obtains by enforcement the present invention can be reduced to below half of conventional products, can allow solar cell use as power generation assembly economically.
The possibility of industrial utilization
According to the present invention, a kind of highly purified polysilicon or silicon for solar cell substrate can only be made with metallurgical method with by continuous flowing water operation. Therefore, can be suitable for the maximization of equipment, and can avoid the waste of energy, be highly suitable for the manufacturing of used for solar batteries substrate.
Claims (21)
1. the manufacture method of a polysilicon is characterized in that, uses following each operation to make polysilicon by Pure Silicon Metal:
A. with Pure Silicon Metal fusion in a vacuum, make phosphorus gasification wherein and it is removed, solidify then from melt, removing impurity component, thereby obtain ingot bar;
B. the part excision of the impurity of above-mentioned ingot bar being concentrated;
C. the remainder after the part that impurity the concentrated excision melts again, then in oxidizing atmosphere with boron and carbon oxidation from melt remove, then in this melt, be blown into the gas mixture of argon gas or argon and hydrogen to carry out deoxidation;
D. the melt after the above-mentioned deoxidation is molded in the mold, carries out directional freeze, obtain ingot bar;
E. the part excision of concentrating of the impurity of the ingot bar that obtains by directional freeze.
2. the manufacture method of polysilicon as claimed in claim 1 is characterized in that, the reduction refining by silicon oxide obtains above-mentioned Pure Silicon Metal.
3. the manufacture method of a polysilicon, it is characterized in that, at first the Pure Silicon Metal of the molten state that the refining by silicon oxide is obtained is transferred in the crucible, oxidation solidifies it after removing boron and carbon in oxidizing atmosphere, then carry out the B operation of claim 1, carry out fusion in a vacuum, carry out C, D and the E operation of claim 1 then.
4. as the manufacture method of each described polysilicon among the claim 1-3, it is characterized in that above-mentioned oxidizing atmosphere is by H
2O, CO
2Or O
2Gas forms, and its consumption is the least possible so that the not oxidized silicon in the interface of above-mentioned melt and gas covers.
5. the manufacture method of polysilicon as claimed in claim 4 is characterized in that, carries out the method for local heating with plasma arc and remove the silicon oxide that generates on the surface of above-mentioned melt.
6. as the manufacture method of each described polysilicon in the claim 1～5, it is characterized in that, use H
2O, CO
2Or O
2Air-blowing goes in the melt to replace above-mentioned in oxidizing atmosphere.
7. as the manufacture method of each described polysilicon in the claim 1～6, it is characterized in that, use SiO
2Or Si
3N
4As above-mentioned releasing agent.
8. as the manufacture method of each described polysilicon in the claim 1～7, it is characterized in that, freezing interface translational speed when solidifying in order to remove above-mentioned impurity is below 5mm/min, and the freezing interface translational speed when carrying out directional freeze is below 2mm/min.
9. as the manufacture method of each described polysilicon in the claim 1～8, it is characterized in that, above-mentioned ingot bar is cut off from this ingot bar lower end height more than 70%.
10. as the manufacture method of each described polysilicon in the claim 1～9, it is characterized in that, the phosphorus concentration in the melt is reduced to below the 0.3ppm.
11. the manufacture method as each described polysilicon in the claim 1～10 is characterized in that, the boron concentration in the melt is reduced to below the 0.6ppm.
12. the manufacture method as each described polysilicon in the claim 1～11 is characterized in that, the carbon concentration in the melt is reduced to below the 10ppm.
13. the manufacturing installation of a polysilicon is characterized in that, this device comprises: be used to melt or the heating unit of heating of metal silicon; Be used to keep the maintenance container of molten metal silicon; The 1st mold of the melt in this maintenance container is used to cast; Surround these and keep container and mold, be used for making phosphorus from underpressure chamber that the melt gasification is removed; Be used for to take from the melting appartus again that the part of the ingot bar of above-mentioned mold melts or heats; Be used to keep the refining vessel of the melt that melts again; The melt that is used in this refining vessel is blown into or jet paraffin oxidation gas, hydrogen or hydrogen-argon-mixed nozzle; Be used for the melt of deoxidation is cast into the 2nd mold of ingot bar.
14. poly plant as claimed in claim 13 is characterized in that, the vacuum tightness in the above-mentioned underpressure chamber is higher than 10
-3Holder.
15. as claim 13 or 14 described poly plants, it is characterized in that, by water-cooling jacket crucible made of copper or plumbago crucible as above-mentioned maintenance container, by SiO
2Matter crucible, SiO
2Mold pressing crucible or SiO
2The lining crucible is as above-mentioned refining vessel.
16., it is characterized in that above-mentioned heating unit is an electron beam gun as each described poly plant in the claim 13～15.
17., it is characterized in that above-mentioned melting appartus again is plasma arc rifle or direct current arc source as each described poly plant in the claim 13～16.
18. as each described poly plant in the claim 13～17, it is characterized in that, the sidewall of the 1st and the 2nd mold is formed by lagging material, and its bottom is formed by water-cooling jacket, and disposes the heating source that is used to heat the melt that is cast into above these molds.
19., it is characterized in that the height H of above-mentioned mold is W/H＞0.5 with the ratio of its diameter W as each described poly plant in the claim 13～18.
20. the manufacture method of a silicon for solar cell substrate is characterized in that, the polysilicon ingot bar that obtains according to each described manufacture method in the claim 1～12 is cut into thin slice.
21. the manufacture method of silicon for solar cell substrate as claimed in claim 20 is characterized in that, the thickness of above-mentioned thin slice is 100～450 μ m.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN96198989A CN1092602C (en) | 1996-10-14 | 1996-10-14 | Process and apparatus for preparing polycrystalline silicon and process for preparing silicon substrate for solar ceu |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN96198989A CN1092602C (en) | 1996-10-14 | 1996-10-14 | Process and apparatus for preparing polycrystalline silicon and process for preparing silicon substrate for solar ceu |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1204298A true CN1204298A (en) | 1999-01-06 |
| CN1092602C CN1092602C (en) | 2002-10-16 |
Family
ID=5129258
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN96198989A Expired - Fee Related CN1092602C (en) | 1996-10-14 | 1996-10-14 | Process and apparatus for preparing polycrystalline silicon and process for preparing silicon substrate for solar ceu |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1092602C (en) |
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| CN1299983C (en) * | 2003-07-22 | 2007-02-14 | 龚炳生 | Method of manufacturing a photovoltaic silicon |
| CN100406378C (en) * | 2000-05-11 | 2008-07-30 | 德山株式会社 | Apparatus for producing polycrystalline silicon |
| CN100408475C (en) * | 2006-10-31 | 2008-08-06 | 锦州新世纪石英玻璃有限公司 | Production process of solar energy grade polysilicon |
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| TWI472485B (en) * | 2007-07-23 | 2015-02-11 | Silicor Materials Inc | Use of acid washing to provide purified silicon crystals |
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| CN102145894B (en) * | 2011-05-16 | 2013-06-05 | 青岛隆盛晶硅科技有限公司 | Method and device for smelting and purifying polysilicon by using electron beams and adopting slag filtering |
| CN105964992A (en) * | 2011-09-16 | 2016-09-28 | 思利科材料有限公司 | Directional solidification system and method |
| CN102701212A (en) * | 2012-05-17 | 2012-10-03 | 华南师范大学 | Method for removing boron and phosphorus and purifying industrial silicon by using metallurgic method |
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