Classifications

• • 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
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B28/00—Production of homogeneous polycrystalline material with defined structure
  • C30B28/04—Production of homogeneous polycrystalline material with defined structure from liquids
  • C30B28/10—Production of homogeneous polycrystalline material with defined structure from liquids by pulling from a melt
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B35/00—Apparatus not otherwise provided for, specially adapted for the growth, production or after-treatment of single crystals or of a homogeneous polycrystalline material with defined structure
• • 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 invention relates to a substantially planar elongated support for manufacturing a polycrystalline silicon-based strip.
• the object of the invention is to produce silicon strips for the manufacture of silicon photovoltaic cells.
• a first method of manufacturing a polycrystalline silicon strip by deposition on such a support is carried out by means of a crucible containing a molten silicon bath, said support being intended to be at least partially immersed in the bath and traversing substantially vertically in the direction of the length the equilibrium surface of the bath.
• RST Silicon Tape on Temporary Carbon Substrate
• the support consists of an expanded and laminated natural graphite primer coated entirely with a protective film of pyrolytic graphite lamellar texture of a few micrometers thick. This coating is conventionally made at a high temperature of between 1900 and 2200 ° C., in an isothermal oven, by pyrolysis under reduced pressure of carbon compounds.
• a second method of manufacturing a polycrystalline silicon strip by deposition on a support is carried out by means of a supply of molten silicon, said support being intended to be displaced substantially horizontally in the direction of the length and to receive the silicon on one of its longitudinal faces. This method is for example described in the patent document FR 2
• the support can be of the same type as before and is drawn horizontally and asymmetrically covered. The silicon is finally deposited on one side of the support.
• the lamellar texture pyrolytic graphite coating is highly resistant to molten silicon during the deposition process over periods of at least 20 seconds.
• This excellent resistance which minimizes the formation of silicon carbide at nanometric thicknesses, subsequently makes it possible to completely burn the substrate at high temperature at 800 or 1200 ° C. and to prepare self-supported silicon layers.
• This type of substrate allows symmetrical vertical pulling, according to the "RST” method, to obtain on either side of the support silicon films whose thickness can be adjusted between 50 and 300 microns or less.
• the primary carbon ribbon is today the cheapest substrate available on the market.
• the subsequent operation of burning the support is long and in practice limits the width of the strips to about ten centimeters.
• An alternative would be to separate the two layers of silicon, for example by mechanical means, to greatly accelerate the burning operation. Such separation routes which involve the implementation of delicate manipulations, are very difficult to achieve, given the fragility of the silicon layers.
• the second horizontal pulling method consists of depositing a silicon film from a bath located above the carbon support.
• the rear face of the support is not exposed to silicon and therefore does not necessarily have to be coated with a protective film.
• the use of a support coated on its two longitudinal sides of pyrolytic graphite results in a significant additional cost of the support.
• the object of the invention is to provide a substantially planar elongated element intended in particular for the manufacture of a polycrystalline silicon-based strip that can be used for the implementation of these two processes, with a substantially vertical draw or draw substantially horizontal, while solving the technical problems mentioned above.
• the invention proposes a substantially planar elongated element intended in particular for manufacturing a polycrystalline silicon-based strip and comprising a primary strip based on expanded and laminated natural graphite, characterized in that said primary ribbon is consisting of at least two secondary tapes superimposed and weakly adherent, said primary tape being coated on its two longitudinal sides with a second protective material.
• Such an element can serve as a support for the manufacture of a polycrystalline silicon strip, whatever the trimming process, without loss of material and therefore without additional cost.
• said secondary ribbons are co-laminated.
• the first material is based on expanded natural graphite and laminated.
• the second material is pyrolytic graphite of lamellar texture.
• the invention also relates to a method for manufacturing a polycrystalline silicon-based strip by depositing on a support element as specified above, by means of a crucible containing a molten silicon bath, said support being intended to be immersed. at least partially in the bath and to pass substantially substantially vertically in the direction of the length of the equilibrium surface of the bath, characterized in that it also comprises a subsequent step of separating said secondary ribbons coated with silicon.
• said separation step is followed by a step of burning the secondary ribbons.
• said separation step is preceded by a step of cutting the edges of said secondary ribbons coated with silicon.
• the duration of the burning operation is reduced by an order of magnitude, of the order of one hour to a few minutes. Ribbons of greater width can be used, allowing the realization of silicon wafers of greater width.
• a machine for the continuous implementation of this method comprises in this order said crucible, a device for drawing said support covered with polycrystalline silicon layers, a device for separating the secondary ribbons and a burning device. of these secondary ribbons.
• the invention finally relates to a method for manufacturing a polycrystalline silicon-based strip by depositing on a part of a support as specified above, by means of a supply of molten silicon, said support portion being intended for being moved substantially horizontally in the longitudinal direction and receiving the silicon on one of its longitudinal faces, characterized in that it comprises a preliminary step of separating said secondary ribbons from said support.
• the support according to the invention it is thus possible to produce particularly thin silicon films, the thickness of which can be adjusted between 200 and 250 ⁇ m, or even less. According to the prior art, these films are of a thickness of the order of 350 to 450 microns or more.
• the method also comprises a step of burning the secondary ribbon.
• the cost of the carbon ribbon is reduced by a factor close to two.
• the invention makes it possible, thanks to rapid burning at high temperature, to minimize the thickness of the silicon layer at values much lower than those currently obtained by current methods.
• the invention is particularly suitable for continuous printing.
• Figure 1 is a sectional view in perspective illustrating the first manufacturing method according to the invention and in detail an element according to the invention in longitudinal section.
• Figure 2 is a schematic view of a manufacturing machine according to the invention.
• Figure 3 is a longitudinal sectional view illustrating the second manufacturing method according to the invention.
• a first method of manufacturing a polycrystalline silicon-based strip by deposition on a support 1 is carried out by means of a crucible 2 containing a bath of molten silicon 3, the support being intended to be at least partially immersed in the bath and to cross in the direction represented by the arrow 5 substantially vertical, in the direction of the length, the equilibrium surface of the bath 4.
• support 1 crosses a slot 6 arranged in the bottom of the crucible 2 and overlaps the equilibrium surface 4 of a silicon layer 7A, 7B on each of its longitudinal faces.
• this low adhesion is achieved by co-rolling of the two secondary ribbons, the conditions of which are chosen to ensure the desired degree of adhesion.
• Element 1 is a symmetrical structure with a complete coating, on both longitudinal faces 1B, 1B 'and on the edges, by the second protective material.
• the secondary strips 1A, 1A ' are made of a natural expanded and laminated graphite material and the protective material is pyrolytic graphite of lamellar texture.
• the two secondary strips 1A, 1A 'fulfill special conditions, which do not contravene the advantages of the known solution: low cost of the primary ribbon and minimal thermoelastic stresses induced in the silicon layers 7A, 7B. These conditions translate by a surface density and a minimum total thickness.
• a known primary tape has a basis weight of the order of 160 g / cm 2 for a thickness of the order of 250 microns.
• the primary ribbon will be obtained by co-laminating two secondary ribbons " IA, 1 A" in order to best approximate these characteristics for vertical draft, although less severe constraints on the density of the surface are feasible and still advantageous for the case of thick silicon layers.
• This separation can be done by simple takeoff, after removal of silicon on the edges of the ribbons.
• the opening of the ribbon field for example by laser cutting, allows to separate in half the support 1 covered with silicon. This separation is assisted by internal forces: under the effect of the stresses induced in the carbon by the contraction of the silicon layers, the composite tape splits in two according to the joining plane of the secondary ribbons 1A, 1A '.
• the separation is done in a continuous process, in line with the draw. It is performed on the ribbon extracted from the draft frame before the thermoelastic stresses induced in the silicon layers 7A, 7B become too high, ie at high temperature, for example around 800 ° C. The two faces of carbon being then released, the operation of burning secondary ribbons and their protective material can be conducted immediately and easily. The two silicon strips 7A, 7B separated from the secondary ribbons are thus extracted continuously.
• FIG. 2 a machine for the continuous implementation of this process is shown diagrammatically in FIG. 2 and comprises, in this order, the crucible 2, a drawing device 10 of the support covered with layers based on polycrystalline silicon, a device for separating 1 1 secondary ribbons each covered with a polycrystalline silicon layer and a burning device 12 of these secondary ribbons and their protective material.
• the separation is performed before the burning operation on long composite strips, which have previously undergone cooling to a temperature which can reach room temperature and possibly various treatments.
• a method of manufacturing a polycrystalline silicon-based strip by deposition on a support 1 ' is carried out, by means of a supply of molten silicon 3, the support being intended to be displaced in the direction of the arrow 5 'substantially horizontal, in the direction of the length and to receive the silicon on one of its longitudinal faces.
• a support 1 as shown in FIG. 1 is initially used.
• This support 1 which is shown in detail in FIG. 1, comprises a primary tape of a first material consisting of at least two secondary tapes 1A, 1A 'which are weakly adherent and coated with a second protective material 1B, 1B'.
• this low adhesion is achieved by co-rolling of the two secondary ribbons, the conditions of which are chosen to ensure the desired degree of adhesion.
• the support 1 is a symmetrical structure with a complete coating, on both longitudinal faces 1B, 1B 'and on the edges, with pyrolytic graphite lamellar texture.
• the secondary strips 1A, 1A ' are made of a natural expanded and laminated graphite material and the protective material is pyrolytic graphite of lamellar texture.
• the secondary ribbons 1A, 1A ' Prior to the deposition phase illustrated in FIG. 3, the secondary ribbons 1A, 1A 'are separated and each half 1' of this initial support 1 is used separately and covered on its upper face coated with silicon 1B protective material. 3 This separation is performed by simply opening the edge of the support 1. This can be achieved mechanically at high speed on industrial cutting machines or more slowly by laser cutting.
• the secondary tape 1 A (or " I A") with its protective material 1 B (or 1 B ') is then burned to obtain a silicon film.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Crystallography & Structural Chemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Physics & Mathematics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• Electromagnetism (AREA)
• General Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Power Engineering (AREA)
• Silicon Compounds (AREA)
• Crystals, And After-Treatments Of Crystals (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=34953725

Family Applications (1)

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Family Cites Families (3)

• 2005
  • 2005-01-19 FR FR0550159A patent/FR2880900B1/fr not_active Expired - Fee Related
  • 2005-12-22 WO PCT/FR2005/051142 patent/WO2006077298A1/fr active Application Filing
  • 2005-12-22 EP EP05825984A patent/EP1874983A1/de not_active Withdrawn

Non-Patent Citations (1)

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