WO2013128758A1 - Moule pour la coulée de silicium, procédé pour la coulée de silicium, matériau de silicium et procédé de fabrication de cellule solaire - Google Patents

Moule pour la coulée de silicium, procédé pour la coulée de silicium, matériau de silicium et procédé de fabrication de cellule solaire Download PDF

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WO2013128758A1
WO2013128758A1 PCT/JP2012/082227 JP2012082227W WO2013128758A1 WO 2013128758 A1 WO2013128758 A1 WO 2013128758A1 JP 2012082227 W JP2012082227 W JP 2012082227W WO 2013128758 A1 WO2013128758 A1 WO 2013128758A1
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silicon
mold
additive
ingot
casting
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PCT/JP2012/082227
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English (en)
Japanese (ja)
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大石　隆一
梶本　公彦
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シャープ株式会社
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Priority to CN201280070752.4A priority Critical patent/CN104159847B/zh
Publication of WO2013128758A1 publication Critical patent/WO2013128758A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1804—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic Table
    • H01L31/182—Special manufacturing methods for polycrystalline Si, e.g. Si ribbon, poly Si ingots, thin films of polycrystalline Si
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/546—Polycrystalline silicon PV cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a silicon casting mold, a silicon casting method using the same, a silicon material, and a solar cell manufacturing method.
  • a polycrystalline silicon wafer which is generally widely used as a substrate for polycrystalline silicon solar cells, is an ingot manufactured by a method called a casting method in which molten silicon is unidirectionally solidified in a mold to obtain a large polycrystalline silicon ingot. It is cut into blocks and made into wafers by slicing.
  • the polycrystalline silicon wafer manufactured by the casting method generally has a distribution in the output characteristics of the solar cell as shown in FIG. 3 depending on the position in the height direction in the ingot or block.
  • the cause of the characteristic distribution of FIG. 3 is generally described as follows. First, in the region I at the initial stage of unidirectional solidification, the characteristics deteriorate due to the influence of impurities diffused from the mold. In the region II on the upper side, since the incorporation of impurities in the raw material due to segregation and the occurrence of crystal defects are few, the characteristics are the best in the block. Further, in the upper region III, the amount of impurities taken into the crystal gradually increases, the generation of crystal defects increases, and the characteristics are deteriorated as compared with the region II.
  • the upper surface portion was formed after the ingot solidified to the end. Impurity reverse diffusion occurs from the high concentration portion of the impurity, and the amount of the impurity further increases, so that the characteristic deterioration becomes more remarkable than in the region III.
  • the influence of impurities in the raw material and impurities eluted from the template is considered, but even if there is no such influence, in regions III and IV, crystals that become minority carrier traps toward the top Since defects increase gradually, the characteristics of solar cells tend to deteriorate.
  • Patent Document 1 Japanese Patent Application Laid-Open No. 2005-152985
  • Patent Document 2 International Publication No. 2005/092791 proposes a method of performing heat flow control during ingot growth with a structure that can change the heat receiving (heat exchange) area.
  • Patent Document 3 Japanese Patent Application Laid-Open No. 2005-132671
  • Patent Document 4 disclose a dendrite as a crystal nucleus at the bottom of an ingot (at the beginning of solidification) by quenching the bottom of the mold.
  • Patent No. 4054873 proposes a method of obtaining a pseudo single crystal by growing crystal pieces (undissolved) left in the melting step of silicon raw material and enlarging crystal grains. ing.
  • Patent Document 6 proposes a method of obtaining a pseudo single crystal by heteroepitaxially growing silicon from a seed crystal such as SiC arranged with the crystal orientation aligned on the bottom of the mold. .
  • Japanese Unexamined Patent Publication No. 2005-152985 International Publication No. 2005/092791 Japanese Patent No. 4203603
  • Japanese Unexamined Patent Publication No. 2005-132671 Japanese Patent No. 4054873
  • Patent Document 1 particularly when the heater is located on the side of the mold, the shape of the solid-liquid interface is further deteriorated, and there is a problem that effects such as reduction of crystal defect density and prevention of cracking cannot be obtained.
  • Patent Document 2 can improve the controllability of heat removal from the mold side wall, the apparatus configuration is very complicated, there are many high-temperature movable parts, and there is a problem that the cost of the apparatus increases and the failure increases. is there.
  • the present invention provides a silicon casting mold, a silicon casting method, a method for producing a silicon material, and a method for producing a solar cell, which can suppress the crystal defect density on the top side of the ingot and enable the production of a solar cell with high cost performance.
  • the task is to do.
  • the inventors of the present invention have made at least the upper surface of the bottom plate part of the mold when producing a silicon ingot by unidirectionally solidifying the silicon melt from the bottom to the top in the mold.
  • the present inventors have found that the above-mentioned problems can be solved by providing a parting material layer containing an additive having a particle size of 0.1 to 3.0 mm in the part, and have reached the present invention.
  • a silicon casting mold for solidifying a silicon melt and an additive having an average particle size of 0.1 to 3.0 mm is included on at least the upper surface of the bottom plate portion of the inner wall of the silicon casting mold.
  • a silicon casting mold provided with a release material layer is provided.
  • a silicon casting method characterized by solidifying a silicon melt in the silicon casting mold, and a silicon material obtained by using silicon cast by the silicon casting method.
  • a manufacturing method and a solar cell manufacturing method using the silicon material as a substrate to obtain a solar cell are provided.
  • a silicon casting mold, a silicon casting method, a silicon material manufacturing method, and a solar cell manufacturing method capable of suppressing the crystal defect density on the top side of the ingot and manufacturing a solar cell with high cost performance Can be provided.
  • the silicon casting mold of the present invention when the release material layer is provided only on the upper surface of the bottom plate portion, when the silicon casting mold is composed of a material mainly composed of graphite or quartz (silica),
  • the additive is mainly composed of at least one selected from silicon nitride, silicon carbide, silicon oxide, and graphite
  • a release material layer is added to the surface at a surface density of 0.2 to 8.5 pieces / cm 2 . The above-described effect is further exhibited when a product is included.
  • the “top of the ingot” means the top of the silicon ingot produced by unidirectionally solidifying the silicon melt in the silicon casting mold from the bottom to the top, that is, the silicon ingot on the side where the solidification process is completed. Means.
  • the lower part of the silicon ingot manufactured in the same manner, that is, the silicon ingot on the side where the solidification process starts is called “bottom of the ingot”.
  • the “silicon material” means “silicon ingot”, “silicon block” processed from a silicon ingot into a prismatic shape, and “silicon wafer” obtained by slicing the silicon block.
  • the “silicon solar battery” means a “silicon solar battery cell” that constitutes a minimum unit and a “solar battery module” in which a plurality of them are electrically connected.
  • the silicon casting mold of the present invention is a silicon casting mold for solidifying a silicon melt, and an additive having an average particle size of 0.1 to 3.0 mm is provided on at least the upper surface of the bottom plate portion of the inner wall of the silicon casting mold. A mold release material layer is provided.
  • the present inventors have been effective as a method for reducing the crystal defect density on the top side of the ingot. It has been found that there is a completely different method other than the stress reduction by suppressing the temperature distribution which is considered to be common and commonly used. Specifically, the present inventors have developed a polycrystal having a small crystal grain size, which is completely opposite to the techniques described in Patent Documents 3 to 6 in which deterioration of characteristics due to grain boundaries is suppressed by coarsening of crystal grains. It has been found that a silicon ingot is more resistant to stress and less prone to crystal defects than a silicon ingot having a large crystal grain size.
  • the density of crystal defects introduced into the inside is large between the grains having a large crystal grain size and the grains having a small crystal grain size even in the portion immediately adjacent to each other in the polycrystalline silicon ingot.
  • the crystal grain on the top side of the silicon ingot is reduced by promoting the generation of crystal nuclei at the bottom of the mold and reducing the crystal grain size. Defects can be reduced.
  • the crystal defects on the top side of the silicon ingot it has been thought that it is necessary to reduce the thermal stress applied to the ingot, such as flattening of the solid-liquid interface.
  • the crystal defects on the top side of the polycrystalline silicon ingot can be reduced only by controlling the crystal grain size to reduce the grain size. By using the template of the present invention, the crystal grain size can be controlled to be small.
  • a release material layer containing an additive having an average particle size of 0.1 to 3.0 mm is provided on at least the upper surface of the bottom plate portion of the inner wall of the silicon casting mold.
  • the material for the silicon casting mold of the present invention is not particularly limited as long as the effect of the present invention is obtained, and a mold of a conventionally used material can be used.
  • the silicon casting mold of the present invention is made of a material mainly composed of graphite or quartz (silica). It is preferable.
  • the shape and dimensions of the mold are not particularly limited as long as the effects of the present invention can be obtained.
  • the shape and dimensions of the mold may be rectangular or cylindrical, and can hold the silicon melt and the solidified silicon ingot. What is necessary is just to have a dimension shape.
  • the mold used in the test example can be mentioned.
  • a mold for silicon casting is usually provided with a release material layer for taking out a silicon ingot from the mold after silicon casting.
  • the mold release material layer contains an additive having a specific average particle diameter. According to the study by the present inventors, the probability that a position where a specific additive is present in the release material layer becomes a nucleus (crystal nucleus) generation position when the silicon melt is solidified is higher than that of other parts. I found it to be higher. In most cases, a silicon ingot is obtained by unidirectionally solidifying the silicon melt in the mold from the bottom plate portion toward the top.
  • the probability of nucleation can be increased by introducing a specific additive into the release material layer on the upper surface portion of the bottom plate portion of the mold where nucleation begins first, and the crystal grain size is reduced. As a result, crystal defects on the top side of the silicon ingot can be suppressed.
  • the release material layer of the silicon casting mold of the present invention is preferably provided only on the upper surface of the bottom plate portion of the inner wall of the silicon casting mold. That is, it is preferable that a release material layer containing no additive is provided on the side surface portion of the inner wall of the mold. If a mold release material layer containing a specific additive is also provided on the side surface of the inner wall of the mold, the probability of nucleation at the side surface increases, and the crystal nucleated at the side surface grows away from the side surface. Thus, the crystal grain boundary may be inclined with respect to the vertical direction of the ingot. Such a crystalline silicon ingot does not have a columnar crystal whose peripheral portion is preferable for solar cells.
  • the additive is not particularly limited as long as the effects of the present invention can be obtained, but considering the influence of impurities mixed into the silicon melt and silicon ingot from the additive, cost, heat resistance, etc.
  • the main component is preferably at least one selected from silicon nitride, silicon carbide, silicon oxide and graphite.
  • the average particle size of the additive is 0.1 to 3.0 mm. If the average particle size of the additive is in the above range, an improvement in the output of a silicon solar cell produced using a silicon ingot produced using the silicon casting mold of the present invention can be expected. This means that the crystal state in the silicon ingot is good, and that it is possible to provide a silicon ingot suitable not only for solar cells but also for other applications.
  • a more preferable range is 0.3 to 2.8 mm, and a further preferable range is 0.8 to 2.2 mm.
  • the average particle size (mm) of specific additives is 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.5, 2.0, 2.5, and 3.0.
  • the release material layer preferably contains an additive at a surface density of 0.2 to 8.5 pieces / cm 2 on the surface thereof. If the surface density is less than 0.2 / cm 2 , the effect of controlling the crystal grain size of silicon may be reduced. On the other hand, when the areal density exceeds 8.5 / cm 2 , the crystal grain size of silicon becomes too small, and the crystal defect density of the ingot top can be kept low, but the crystal that becomes the recombination center of the electron-hole pair There may be too many grain boundaries.
  • Such a silicon ingot is not preferable from the viewpoint of the conversion efficiency of the solar cell, and the range of the surface density of the additive is within the optimum range, and a more preferable range is 2.0 to 6.5 pieces / cm 2 . A more preferable range is 2.5 to 6.0 / cm 2 . Specific areal densities (pieces / cm 2 ) are 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0. .
  • the silicon casting mold of the present invention can be produced by a known method, and is not particularly limited.
  • it can be produced as follows. That is, the base material of the release material layer and the above additives are dispersed in a solvent to prepare a slurry having a solid concentration of about 1 to 5%, and the obtained slurry is applied to the inner surface of the mold. Is dried and fired to obtain a release material layer.
  • the amounts of the main material powder and the additive powder may be appropriately set so that the surface density of the additive on the surface of the release material layer falls within the above range.
  • a known release material can be used, and examples thereof include powders of silicon nitride, silicon oxide and mixtures thereof having an average particle size of 0.1 to 60 ⁇ m. Specific average particle diameters ( ⁇ m) are 0.1, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5. , 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10, 15, 20, 25, 30 , 35, 40, 45, 50, 55, 60.
  • the solvent is not particularly limited as long as it disappears in the firing step and does not adversely affect the release material layer, and examples thereof include polyvinyl alcohol.
  • the coating, drying and firing steps can be performed by appropriately setting conditions by a known method, and the coating and drying steps may be repeated a plurality of times in order to obtain a release material layer having a predetermined film thickness.
  • the firing temperature and the time thereof are about 800 to 1100 ° C. and about 1 to 8 hours, although depending on conditions such as the material used and the thickness of the release material layer to be formed.
  • Specific firing temperatures (° C.) are 800, 825, 850, 875, 900, 925, 950, 975, 1000, 1025, 1050, 1075, 1100, and specific firing times (hours) are 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, and 8.
  • the film thickness of the release material layer is about 150 to 600 ⁇ m.
  • the film thickness of the release material layer is thinner than the particle size of the additive, the effect of the present invention can be easily obtained.
  • the film thickness of the release material layer is thicker than the particle size of the additive, the additive is embedded inside the release material layer, and the surface shape of the release material layer is not reflected in the shape of the additive, Since the density of the convex portion of the additive serving as a nucleation site is reduced, the effect of the present invention is hardly obtained.
  • Specific film thicknesses ( ⁇ m) are 150, 175, 200, 225, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, and 600.
  • only the slurry containing the additive may be applied to form the release material layer having a predetermined thickness.
  • a release material layer composed of a plurality of types of layers may be formed by applying a slurry containing an additive after applying a slurry containing only the main material without containing any material.
  • the release material layer is preferably provided only on the upper surface of the bottom plate portion of the mold.
  • a release material layer containing an additive may be formed only on the upper surface of the bottom plate portion of the mold, and a release material layer not containing the additive may be formed on the side surface of the mold.
  • the silicon casting method of the present invention is characterized by solidifying the silicon melt in the silicon casting mold of the present invention. According to this method, a silicon ingot suitable for a solar cell with high cost performance can be manufactured.
  • the silicon melt in the silicon casting mold may be obtained by melting a solid silicon raw material in the mold or by pouring the silicon melt into the mold.
  • the form of solidification of the silicon melt is not particularly limited as long as the effects of the present invention can be obtained, and conditions may be set as appropriate depending on the apparatus to be used.
  • the silicon casting method of the present invention can be carried out using, for example, a known apparatus as shown in FIG. 4, but the present invention is not limited to this embodiment.
  • FIG. 4 is a schematic sectional view showing an example of a casting apparatus to which the silicon casting method of the present invention can be applied.
  • This apparatus is generally used for casting a polycrystalline silicon ingot, and has a chamber (sealed container) 7 constituting a resistance heating furnace.
  • a mold 1 made of graphite, quartz (SiO 2 ) or the like is disposed inside the chamber 7 so that the atmosphere inside the chamber 7 can be maintained in a sealed state.
  • a graphite mold table 3 that supports the mold 1 is disposed in the chamber 7 in which the mold 1 is accommodated.
  • the mold table 3 can be moved up and down by the lift drive mechanism 12, and the refrigerant (cooling water) in the cooling tank 11 is circulated therein.
  • An outer mold 2 made of graphite or the like is disposed on the upper part of the mold table 3, and the mold 1 is disposed therein.
  • a cover made of graphite or the like surrounding the mold 1 may be arranged.
  • a resistance heater 10 such as a graphite heater is disposed so as to surround the outer mold 2, and a heat insulating material 8 is disposed so as to cover these from above.
  • the resistance heating body 10 can be heated from the periphery of the mold 1 to melt the silicon raw material 4 in the mold 1.
  • the resistance heating method is used as the heating element, but an induction heating method may be used.
  • thermocouple 5 In order to detect the temperature of the bottom surface of the mold 1, a lower mold thermocouple 5 is disposed near the center of the lower surface of the mold 1, and an outer lower mold thermocouple 6 is disposed near the center of the lower surface of the outer mold. And the heating state by the resistance heater 10 is controlled.
  • a thermocouple or a radiation thermometer for detecting the temperature may be disposed, and the thermocouple installation position is not particularly limited.
  • the inside of the chamber 7 can be kept in a sealed state so that external oxygen gas, nitrogen gas, etc. do not flow in.
  • an inert gas such as argon gas is introduced to maintain an inert atmosphere.
  • the apparatus having such a configuration, basically, filling of the silicon raw material 4 into the mold 1, degassing (evacuation) and gas replacement in the chamber 7 by introducing an inert gas, melting of the silicon raw material 4 by heating,
  • the polycrystalline silicon ingot is cast by the steps of melting confirmation and holding, temperature control and solidification start by operation of the lifting drive mechanism 12, solidification completion confirmation and annealing, and ingot removal.
  • an example of an apparatus of a type that heats and melts a silicon raw material in a mold is given, but other than that, a silicon raw material is heated and melted in a crucible or the like different from a silicon casting mold, and a silicon melt is converted into silicon
  • a type of apparatus that pours into a casting mold can also be used.
  • the silicon material of the present invention is produced by the silicon casting method of the present invention. That is, the silicon material of the present invention includes, for example, a “polycrystalline silicon ingot” produced by solidifying the silicon melt in the silicon casting mold of the present invention, and a “polycrystalline silicon block” obtained by cutting it into a prismatic shape. And a “polycrystalline silicon wafer” obtained by slicing the same. These silicon materials are suitable for materials for solar cells with high cost performance.
  • the “polycrystalline silicon block” can be obtained, for example, by processing the above-mentioned “polycrystalline silicon ingot” into a prismatic shape and a desired size using a known apparatus such as a band saw. In the processing, the surface portion of the polycrystalline silicon ingot where impurities such as a mold material may be diffused may be cut, and the surface of the polycrystalline silicon block may be polished if necessary.
  • the “polycrystalline silicon wafer” can be obtained, for example, by slicing the above “polycrystalline silicon block” to a desired thickness using a known apparatus such as a multi-wire saw. At present, a thickness of about 170 to 200 ⁇ m is generally used, but the trend is to reduce the thickness for cost reduction. Further, if necessary, the surface of the polycrystalline silicon wafer may be polished.
  • the silicon solar cell of the present invention is manufactured using the silicon material (polycrystalline silicon wafer) of the present invention as a substrate.
  • silicon solar cells have various structures, these can be manufactured by a known solar cell process using the silicon wafer of the present invention.
  • an n-type impurity for example, phosphorus
  • a front electrode and a back electrode To obtain a polycrystalline silicon solar battery cell.
  • a p-type impurity for example, boron
  • a front electrode and a back surface An electrode is formed to obtain a polycrystalline silicon solar cell.
  • MIS type solar cells in which a metal is deposited with a thin insulating layer interposed therebetween, for example, a silicon thin film of an amorphous type having a conductivity type opposite to a silicon wafer is formed.
  • p-type and n-type silicon heterojunctions having different structures.
  • a polycrystalline silicon solar cell module is obtained by electrically connecting a plurality of them.
  • Test Example 1 Examination on average particle diameter of additive contained in release material layer Quartz made by applying a release material layer containing additives of various materials having specific average particle diameter only on the upper surface of the mold bottom plate A polycrystalline silicon ingot is manufactured using the silicon casting mold 1, a polycrystalline silicon wafer is processed from the obtained ingot, a silicon solar cell is manufactured using the obtained wafer, and the obtained solar cell The relationship between the output and the average particle size of the additive was evaluated.
  • a silicon nitride powder having a particle diameter of 1 to 60 ⁇ m as a main material of the release material layer and a 3% polyvinyl alcohol aqueous solution are mixed so that the weight ratio is 1: 1, and the additive powder shown in Table 1 is added and dispersed.
  • a slurry A was obtained.
  • the amount of the additive powder was appropriately set so that the surface density of the additive was about 3.0 / cm 2 as described below.
  • a silicon nitride powder and a 3% polyvinyl alcohol aqueous solution were mixed so that the weight ratio was 1: 1 and dispersed to obtain slurry B.
  • the side surface portion of the mold was coated with only slurry B and dried at about 50 ° C., and the resulting coating film was baked at 900 ° C. for 2 hours to form a release material layer having a thickness of about 250 ⁇ m on the side surface portion of the mold.
  • the release material layer whose coating method is shown as “surface layer” in Table 1 is composed of a lower layer containing no additive and an upper layer containing the additive, and was formed as follows.
  • the obtained slurry B is applied only to the upper surface of the bottom plate portion of the mold and dried at about 50 ° C.
  • the obtained slurry A is applied only to the upper surface of the bottom plate portion of the mold and dried at about 50 ° C.
  • the release material layer whose application method is shown as “mixing” in Table 1 consists of only the layer containing the additive, and was formed as follows.
  • the obtained slurry A was applied only to the upper surface of the bottom plate portion of the mold and dried at about 50 ° C., and the obtained coating film was baked at 900 ° C. for 2 hours to obtain an additive surface density of about 3.0 / cm 2.
  • a release material layer having a thickness of about 250 ⁇ m was formed.
  • application and drying of the slurry were repeated as appropriate.
  • said baking was performed simultaneously about the coating film of a mold side surface and a baseplate part upper surface.
  • the slurry A containing silicon nitride powder and additive as the main material was used, but slurry containing only the additive can also be used.
  • silicon nitride is used as the main material of the release material
  • the present invention is not limited to silicon nitride, and other materials or a multiple layer structure of silicon nitride and silicon oxide may be used. It may be within the range where the effects of the invention can be obtained.
  • the graphite outer mold 2 (inner dimensions: 900 mm ⁇ 900 mm ⁇ height) 460 mm, bottom plate thickness and side wall thickness 20 mm) were set, and quartz mold 1 (inner dimensions: 830 mm ⁇ 830 mm ⁇ 420 mm, bottom plate thickness and side wall thickness 22 mm) was set therein. Further, thermocouples 5 and 6 for temperature measurement were respectively installed at two locations near the center of the lower surface of the mold 1 and near the center of the lower surface of the outer mold 2.
  • Each obtained polycrystalline silicon ingot was processed into 25 polycrystalline silicon blocks (156 mm ⁇ 156 mm ⁇ 200 mm) using a band saw, further sliced using a wire saw, and then a polycrystalline silicon wafer (156 mm ⁇ 156 mm). X thickness 0.18 mm) About 12,000 sheets were obtained.
  • the obtained polycrystalline silicon wafer is put into a normal solar cell process to produce about 12,000 solar cells (outer dimensions 156 mm ⁇ 156 mm ⁇ thickness 0.18 mm) per ingot, and its output (W) was measured.
  • Table 1 shows the result of calculating and standardizing the average value of the output for each ingot unit. For normalization, the average output of solar cells obtained from an ingot cast from a mold in which a release material layer containing no additive was formed was used, and the average of the outputs calculated in units of each ingot when this was taken as 100. The value was calculated.
  • FIG. 1 shows the relationship between the particle size of the additive contained in the release material layer of the mold for casting silicon and the average output of the solar battery cell.
  • the average output of the solar battery cell depends on the average particle diameter of the additive regardless of the material of the additive, silicon carbide, silicon oxide, silicon nitride and graphite. I understand that. That is, when the average particle diameter of the additive is in the range of 0.1 to 3.0 mm, the average output is improved as compared with the case of only the release material layer not containing the additive. Particularly when the average particle size of the additive is in the range of 0.3 to 2.8 mm, the improvement rate of the relative average output is 0.5% or more, and the average particle size of the additive is 0.8%. In the range of ⁇ 2.2 mm, the relative average output improvement rate is a preferable result of 1.0% or more.
  • the output of the solar battery module manufactured using the solar battery cells with improved average output is improved. Further, when the average particle size of the additive is in the range of 0.1 to 3.0 mm, there is no crack on the bottom side of the silicon block, which is good.
  • Test Example 2 Examination of surface density of additives contained in mold release material layer Only the upper surface of the mold bottom plate portion includes a material having an area density of a specific additive and additives of various materials having an average particle diameter of 0.8 mm.
  • a polycrystalline silicon ingot was produced in the same manner as in Test Example 1 using a quartz silicon casting mold 1 coated with a mold material layer, and a polycrystalline silicon wafer was processed from the obtained ingot.
  • a silicon solar cell was produced using the wafer, and the relationship between the output of the obtained solar cell and the surface density of the additive was evaluated.
  • FIG. 2 shows the relationship between the surface density of the additive contained in the release material layer of the silicon casting mold and the average output of the solar cells.
  • the average output of the solar cell depends on the surface density of the additive, regardless of the material of the additive and the method of applying the release layer. That is, when the surface density of the additive is in the range of 0.2 to 8.5 pieces / cm 2 , the average output is improved as compared with the case of only the release material layer not containing the additive. In particular, when the surface density of the additive is in the range of 2.0 to 6.5 pieces / cm 2 , the improvement rate of the relative average output is 0.5% or more, and the surface density of the additive is 2%. In the case of the range of 0.5 to 6.0 / cm 2 , the improvement rate of the relative average output is a preferable result of 1.0% or more.

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  • Power Engineering (AREA)
  • Photovoltaic Devices (AREA)
  • Silicon Compounds (AREA)

Abstract

Un moule pour la coulée de silicium pour solidifier une masse fondue de silicium, le moule de coulée de silicium ayant une couche de démoulage comprenant un additif ayant un diamètre de particule moyen de 0,1 à 3,0 mm disposé au moins sur la surface supérieure de la plaque de fond des parois internes du moule pour la coulée de silicium.
PCT/JP2012/082227 2012-02-28 2012-12-12 Moule pour la coulée de silicium, procédé pour la coulée de silicium, matériau de silicium et procédé de fabrication de cellule solaire WO2013128758A1 (fr)

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JP2012042116A JP6014336B2 (ja) 2012-02-28 2012-02-28 シリコン鋳造用鋳型、シリコン鋳造方法、シリコン材料の製造方法および太陽電池の製造方法

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CN104159847A (zh) 2014-11-19
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TW201335443A (zh) 2013-09-01
TWI458863B (zh) 2014-11-01
CN104159847B (zh) 2016-10-19

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