WO2009026915A2 - Procédé de fabrication de tiges de silicium polycristallines et tige de silicium polycristalline - Google Patents

Procédé de fabrication de tiges de silicium polycristallines et tige de silicium polycristalline Download PDF

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Publication number
WO2009026915A2
WO2009026915A2 PCT/DE2008/001459 DE2008001459W WO2009026915A2 WO 2009026915 A2 WO2009026915 A2 WO 2009026915A2 DE 2008001459 W DE2008001459 W DE 2008001459W WO 2009026915 A2 WO2009026915 A2 WO 2009026915A2
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WO
WIPO (PCT)
Prior art keywords
silicon
rods
rod
thin
doping
Prior art date
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PCT/DE2008/001459
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German (de)
English (en)
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WO2009026915A3 (fr
Inventor
Hubert Aulich
Friedrich-Wilhelm Schulze
Original Assignee
Pv Silicon Forschungs Und Produktions Gmbh
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Application filed by Pv Silicon Forschungs Und Produktions Gmbh filed Critical Pv Silicon Forschungs Und Produktions Gmbh
Publication of WO2009026915A2 publication Critical patent/WO2009026915A2/fr
Publication of WO2009026915A3 publication Critical patent/WO2009026915A3/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
    • C01B33/021—Preparation
    • C01B33/027—Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material
    • C01B33/035—Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material by decomposition or reduction of gaseous or vaporised silicon compounds in the presence of heated filaments of silicon, carbon or a refractory metal, e.g. tantalum or tungsten, or in the presence of heated silicon rods on which the formed silicon is deposited, a silicon rod being obtained, e.g. Siemens process

Definitions

  • the invention relates to a process for the production of polycrystalline silicon, in particular for solar applications and silicon rods produced by this process, which can be used directly as starting material in a subsequent process for the production of multicrystalline or monocrystalline silicon crystals.
  • Polycrystalline silicon is used as a starting material of silicon for semiconductors and as a raw material of solar cells. With the proliferation of solar cells, the demand for polycrystalline silicon, which is a raw material for it, has also increased.
  • the basic manufacturing process for polycrystalline silicon has been almost identical for both electronics and the solar industry; It is based on the so-called Siemens process, which was invented 50 years ago. In this Siemens process is polycrystalline silicon obtained with high purity by hydrogen reduction of trichlorosilane.
  • the basic structure of a Siemens CVD reactor has already been described in DE 1 061 593.
  • Electricity to be heated Because it is high-purity silicon, very high electrical voltages in the range of 5,000 to 10,000 volts must either be applied which is very costly and not previously usual, or the Si thin rods must with external sources of heat to a temperature of about 450 0 C preheated. The further heating to about 1,100 0 C can then be done by direct passage of current with voltages below 1,500 volts.
  • Trichlorosilane and hydrogen as the reducing agent are fed into the reactor from below to reduce the chlorosilane, whereby the resulting silicon selectively deposits on the surfaces of the Si thin rods, thereby forming a rod-like polycrystalline silicon.
  • the resulting Silicon rods can be appropriately doped in further processes, converted into crystals and subsequently cut into wafers.
  • EP 1392601 describes a process for the production of polycrystalline silicon according to the Siemens process, in which trichlorosilane is first reacted with hydrogen to form silicon and a leaving mixture comprising silicon tetrachloride (STC), unreacted trichlorosilane (TCS) and a little dichlorosilane , Subsequently, the exit mixture is decomposed into its components. The unreacted TCS is returned to the deposition process while the STC is either converted back to TCS via a hydrogenation process or put to a totally different use.
  • STC silicon tetrachloride
  • TCS unreacted trichlorosilane
  • dichlorosilane a little dichlorosilane
  • a disadvantage of the usual Siemens method is that the thin rods, which consist of the purest silicon, must be preheated by external heat sources to min. 450 0 C, so that their electrical
  • Conductivity is so high that they can be heated by direct passage of current to the required deposition temperature of about 1100 0 C. Therefore, a separate complex process for heating the thin rods is necessary.
  • Halogenosilane to produce a plasma discharge to a halogenated Polysilane, which is subsequently decomposed in a second step under heating to silicon.
  • the silicon rods produced in the Siemens process must be correspondingly doped in further processes.
  • dopants may optionally be added to the reaction gas mixture for doping the Si rods. This method has the disadvantage that the admixture of the necessary dopants during the deposition process must be precisely controlled.
  • the object is to provide a method with which polycrystalline silicon for the production of solar cells can be produced inexpensively and the silicon rods produced by this method have such a doping that they directly in subsequent processes to a multicrystalline or single crystal silicon crystal can be further processed.
  • trichlorosilane reacts with hydrogen according to the Siemens method and silicon is deposited on the Si thin rods.
  • the Si thin rods used according to the invention are doped in such a way with boron and optionally with other doping substances, in contrast to the rods usually undoped in the Siemens method, in such a way that they have a Such electrical conductivity .auf hypoxia . Thomas hypoxia a current flow through the doped Si thin rods, which is effected by the application of a voltage, this heats up to the necessary deposition temperature. Thus, no external heating of the Si thin rods is required in the starting phase of the deposition u ng.
  • the thin rods are made of the purest silicon, which are produced from the purest silicon rods for the semiconductor industry.
  • These conventional Si thin rods have such high electrical resistance at room temperature that no current flow occurs. Therefore, in the prior art methods, additional heating of the Si thin rods in the starting phase of the CVD deposition process is required.
  • the Si thin rods are doped such that they have such electrical conductivity in that they only heat up to the necessary deposition temperature due to the flow of current.
  • the Si thin rods used are doped with boron in such a way that they have an electrical conductivity of preferably 0.05 to 1 ohm * cm, allowing a flow of current at room temperature.
  • Voltage applied to the Si thin rods to ignite the CVD process is preferably about 1000 to 1400 V.
  • the deposition temperature at the Si thin rods is about 1100 0 C.
  • the Si thin rods used according to the invention can be doped with boron and, if appropriate, with other, suitable substances in such a way that the ready-to-finish CVD process is complete
  • Silicon rod which is used to produce a crystal rod in subsequent If the method is melted, it has such a "total doping" which is desired for the silicon crystals and cut wafers produced in subsequent processes, and thus no further method steps are required for doping the Si rods.
  • the silicon rod produced by the process according to the invention is characterized by the features of claim 2.
  • the present after completion of the CVD process (“harvested") silicon rod has a characteristic distribution of electrical conductivity in cross-section, wherein the core of the silicon rod, the zu At the beginning of the CVD process, the Si thin rod corresponds to a significantly higher electrical conductivity, whereas the silicon body deposited therefrom, which consists of the purest silicon, has a considerably lower electrical conductivity
  • the silicon rod present at the end of the CVD process is now available as a finished product for further processing for a crystal pulling process to a preferably multicrystalline or monocrystalline silicon crystal. For this it is broken and melted.
  • this melt produced from the silicon rod according to the invention now has such a "total doping", which is required for the production of wafers for a solar cell.
  • the Si thin rods can be doped with boron that the Si thin rods have such electrical conductivity that they reach the required deposition temperature exclusively by the applied voltage.
  • additional apparatus devices for heating the Si thin rods can be omitted during the startup phase.
  • the subsequent doping processes can be omitted, since the finished silicon rod has such a "total doping", which is required for the production of a polycrystalline or monocrystalline silicon crystal and for further processing into wafers for a solar cell.
  • Trichlorosilane is reacted in a Siemens reactor by a known CVD process, wherein pure silicon is deposited on heated Si thin rods and the exhaust gas consisting of hydrogen chloride, silicon tetrachloride and unreacted trichlorosilane leaves the reactor.
  • the Si thin rods which have a diameter of preferably 5 to 10 mm, are doped with boron in such a way that they have an electrical conductivity in the range of 0.05 to 1 ohm / cm. With this electrical conductivity flows when applying a voltage of max.
  • a silicon rod produced by the method according to the invention has a characteristic distribution of the electrical conductivity in cross-section.
  • the core of the silicon rod corresponds to the doped Si thin rod used at the beginning of the CVD process, on the surface of which pure silicon has been deposited. Since the deposited silicon is very pure and has a very low electrical conductivity, the doped core has a significantly higher electrical conductivity, which is preferably 0.05 to 1 ohm * cm.
  • the electrical conductivity of the core is determined by the doping of the Si thin rod.
  • the finished silicon rod has • a basic doping with boron, which has an electrical conductivity of 0.5 to 10 ohm * cm, • a doping with n-doping substances, which cause an electrical conductivity> 1, 0 ohm * cm,
  • the silicon rod present at the end of the CVD process is now available as a finished product for further processing for a crystal pulling process into a polycrystalline or monocrystalline silicon crystal.
  • it can be achieved by a corresponding doping of the Si thin rod that the silicon rod has such a "total doping" which is required for the production of wafers for a solar cell Since only the Si thin rod has been doped, the dopants are uneven in the silicon rod However, since the silicon rod is refracted and reflowed for further processing, it is achieved that the dopants are now distributed almost homogeneously in the melt produced from the silicon rod according to the invention
  • the homogeneous crystal growth process results in a homogeneous distribution of the dopants in the crystal which, later on, the wafers are cut, and no further process steps are required for doping the silicon to achieve the desired electrical conductivity.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Silicon Compounds (AREA)

Abstract

L'invention concerne un procédé de fabrication de silicium polycristallin notamment destiné à des applications solaires, et des tiges de silicium fabriquées au moyen de ce procédé. Auparavant, les résidus de la fabrication de silicium ultra-pur étaient employés pour la fabrication de silicium pour des applications solaires. Les tiges fines employées dans le procédé Siemens pour le démarrage du processus sont habituellement composées de silicium ultra-pur et doivent être chauffées de façon externe pour permettre le passage du courant. Selon l'invention, du silicium est déposé sur des tiges fines de Si dopées selon le procédé Siemens. Ces tiges fines de Si sont dopées avec du bore et éventuellement avec d'autres dopants de telle manière qu'elles présentent une conductivité électrique permettant un passage du courant au travers des tiges fines de Si en cas d'application d'une tension < 1400 V, le passage du courant chauffant les tiges à la température de dépôt nécessaire. Les tiges fines de Si sont avantageusement dopées de telle manière que la tige de silicium présente un 'dopage total' nécessaire à la fabrication de plaquettes pour une cellule solaire. Ainsi, les tiges de Si fabriquées selon l'invention peuvent être employées directement en tant que matériau de départ dans un procédé consécutif pour la fabrication de cristaux de silicium polycristallins ou monocristallins.
PCT/DE2008/001459 2007-08-30 2008-08-28 Procédé de fabrication de tiges de silicium polycristallines et tige de silicium polycristalline WO2009026915A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102007041803.7 2007-08-30
DE200710041803 DE102007041803A1 (de) 2007-08-30 2007-08-30 Verfahren zur Herstellung von polykristallinen Siliziumstäben und polykristalliner Siliziumstab

Publications (2)

Publication Number Publication Date
WO2009026915A2 true WO2009026915A2 (fr) 2009-03-05
WO2009026915A3 WO2009026915A3 (fr) 2010-04-01

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DE (1) DE102007041803A1 (fr)
WO (1) WO2009026915A2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9255325B2 (en) 2010-07-23 2016-02-09 Centrotherm Sitec Gmbh Method and apparatus for igniting silicon rods outside a CVD-reactor

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE202012100839U1 (de) * 2012-03-08 2012-06-22 Silcontec Gmbh Laborreaktor
US10392725B2 (en) 2017-09-19 2019-08-27 Frank Asbeck Method for depositing silicon feedstock material, silicon wafer, solar cell and PV module

Citations (5)

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US3899557A (en) * 1972-10-31 1975-08-12 Siemens Ag Hollow semiconductor bodies and method of producing the same
DE2447691A1 (de) * 1974-10-07 1976-04-08 Siemens Ag Verfahren zum herstellen von reinem silicium
US4345142A (en) * 1975-12-03 1982-08-17 Siemens Aktiengesellschaft Directly heatable semiconductor tubular bodies
WO2002100776A1 (fr) * 2001-06-08 2002-12-19 Hemlock Semiconductor Corporation Procede de preparation de silicium polycristallin
WO2006018100A1 (fr) * 2004-08-10 2006-02-23 Joint Solar Silicon Gmbh & Co. Kg Reacteur et procede pour produire du silicium

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DE1061593B (de) 1956-06-25 1959-07-16 Siemens Ag Vorrichtung zur Gewinnung reinsten Halbleitermaterials fuer elektrotechnische Zwecke
DE1283814B (de) * 1965-01-20 1968-11-28 Siemens Ag Verfahren zur Stabilisierung der elektrischen Leitfaehigkeit von Silicium
DE2116746C3 (de) * 1971-04-06 1978-12-07 Siemens Ag, 1000 Berlin Und 8000 Muenchen Verfahren zum Herstellen von Halbleiterstäben durch thermische Zersetzung einer Halbleiterverbindung
FR2530638A1 (fr) * 1982-07-26 1984-01-27 Rhone Poulenc Spec Chim Procede de preparation d'un melange a base de trichlorosilane utilisable pour la preparation de silicium de haute purete
US4526769A (en) * 1983-07-18 1985-07-02 Motorola, Inc. Trichlorosilane production process
US4575401A (en) * 1984-06-07 1986-03-11 Wedtech Corp Method of and apparatus for the drawing of bars of monocrystalline silicon
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DE19534922C1 (de) * 1995-09-21 1997-02-20 Wacker Chemie Gmbh Verfahren zur Herstellung von Trichlorsilan und Silicium
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WO2003040036A1 (fr) * 2001-10-19 2003-05-15 Tokuyama Corporation Procede de production de silicium
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Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3899557A (en) * 1972-10-31 1975-08-12 Siemens Ag Hollow semiconductor bodies and method of producing the same
DE2447691A1 (de) * 1974-10-07 1976-04-08 Siemens Ag Verfahren zum herstellen von reinem silicium
US4345142A (en) * 1975-12-03 1982-08-17 Siemens Aktiengesellschaft Directly heatable semiconductor tubular bodies
WO2002100776A1 (fr) * 2001-06-08 2002-12-19 Hemlock Semiconductor Corporation Procede de preparation de silicium polycristallin
WO2006018100A1 (fr) * 2004-08-10 2006-02-23 Joint Solar Silicon Gmbh & Co. Kg Reacteur et procede pour produire du silicium

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9255325B2 (en) 2010-07-23 2016-02-09 Centrotherm Sitec Gmbh Method and apparatus for igniting silicon rods outside a CVD-reactor

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WO2009026915A3 (fr) 2010-04-01
DE102007041803A1 (de) 2009-03-05

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