Abstract: The invention provides a process for determining surface contamination of polycrystalline silicon, including the steps of: a) providing two polycrystalline silicon rods by deposition in a Siemens reactor; b) determining contaminants in the first of the two rods immediately after the deposition; c) conducting the second rod through one or more systems in which polycrystalline silicon rods are processed further to give rod pieces or polysilicon fragments, optionally cleaned, stored or packed; d) then determining contaminants in the second rod; wherein the difference in the contaminants determined in the first and second rods gives surface contamination of polycrystalline silicon resulting from systems and the system environment.

Abstract: Polycrystalline silicon with low contamination by impurities, especially boron and phosphorus, is manufactured by the Siemens process or by the fluidized bed process, in which deposition of polycrystalline silicon takes place in a reactor maintained within a clean room of the 1 to 100,000 class, and air entering the facility enclosing the reactors is filtered by a multiple stage filtration system wherein coarse and fine filter elements contain less than 0.1% by weight of boron and phosphorus and less than 0.01% by weight of arsenic and aluminum. Following production of the polycrystalline silicon, the polycrystalline silicon may be further treated by steps such as comminution, classifying, wet-chemical treatment, and packing, all these further steps also preferably taking place within a clean room of the 1 to 100,000 class.

Abstract: A bag contains polysilicon, has been welded and includes at least one weld seam and a polyethylene film having: a thickness of 150-900 ?m; a stiffness at a flexural modulus Fmax of 300-2000 mN and Ft of 100-1300 mN; a fracture force F determined by dynamic penetration testing of 200-1500 N; a fracture energy Ws of 2-30 J; a penetration energy Wtot of 2.2-30 J; a film tensile stress at 15% longitudinal and transverse elongation of 9-50 MPa; an Elmendorf longitudinal film tear resistance of 10-60 cN; an Elmendorf transverse film tear resistance of 18-60 cN; a longitudinal film elongation at break of 300-2000%; a transverse film elongation at break of 450-3000%; and a weld seam strength of 25-150 N/15 mm. A method includes filling a bag with polysilicon, and welding by pulse sealing with contact pressure greater than 0.01 N/mm2 to obtain a 25-150 N/15 mm weld seam strength.

Abstract: Polycrystalline silicon having a low P, B, and other extraneous element contamination is produced by performing at least one process step in a cleanroom of class 1 to 100,000, wherein air is conducted into the cleanroom through at least one filter for separating particles ?1 ?m, and one filter for particles <1 ?m, the filters being made of low contamination materials.

Abstract: Polysilicon fragments are purified to remove metal contaminates by contacting the fragments with a purifying liquid at a flow rate >100 mm/sec. Effective removal without abrasion is accomplished.

Abstract: Polysilicon rods from the Siemens process are crushed into fragments and further processed to fragments having very low metal contamination in an economical manner by purposefully fabricating parts contacting the polysilicon from materials which cause high metal contamination, and removing the metal contamination by a cleaning bath or baths tailored to the particular metal contamination. By this process, economical materials previously scrupulously avoided, such as low alloy steel, can be used for crushers, conveyors, and other polysilicon-contacting parts of the crushing and classifying system.

Abstract: The present invention relates to polycrystalline silicon chunks which are cubic and have a metal content of less than 200 pptw and a dopant content of less than 50 ppta. Methods for producing polycrystalline silicon chunks, include the steps of providing a polycrystalline silicon rod, comminuting the polycrystalline silicon rod into cubic chunks, and cleaning the polycrystalline silicon chunks, wherein comminution takes place using a spiked-roll crusher having at least one spiked roll, the spiked roll including W2C phases or WC phases with 0.1-10% of a metal carbide selected from the group consisting of titanium carbide, chromium carbide, molybdenum carbide, vanadium carbide, and nickel carbide or consisting of steel with 1-25% W.

Abstract: Disclosed is a process for cleaning polycrystalline silicon chunks in an acidic cleaning bath, wherein: (a) the cleaning includes several cleaning cycles, (b) a particular amount of acid is consumed in each cycle, (c) a computer-controlled dosage system integrator adds up those amounts of acid consumed in each cycle to give a current total consumption of acid in the bath, and (d) on attainment of a total consumption of acid in the bath corresponding to an optimal dosage of the dosage system, the dosage system supplies this optimal dosage of unconsumed acid withdrawn from a reservoir vessel to the bath. Another process for cleaning polycrystalline silicon chunks in an acidic cleaning bath includes an acid circuit in which acid is circulated, wherein the ratio of amount of acid circulated in liters to the mass of polysilicon chunks present in the bath in kg is greater than 10.

Abstract: The invention provides a polycrystalline silicon chunk having a concentration of 1-50 ppta of boron and 1-50 ppta of phosphorus at the surface.

Abstract: Polysilicon fragments are purified to remove metal contaminates by contacting the fragments with a purifying liquid at a flow rate >100 mm/sec. Effective removal without abrasion is accomplished.

Abstract: An automated filling system for introducing crushed polysilicon fragments into shipping bags without significant contamination positions a freely suspended energy absorber into a freely suspended bag of non-contaminating material prior to filling, and following filling, the energy absorber is removed, and the bag is sealed. The system can replace manual packaging which has been required for semiconductor applications.

Abstract: A breathable polyethylene glove as an overglove, over a cut- and puncture-resistant and nonfuzzing underglove, is useful for the non-contaminating packing of high-purity silicon, such as chunk polysilicon and silicon wafers.

Abstract: A bag contains polysilicon, has been welded and includes at least one weld seam and a polyethylene film having: a thickness of 150-900 ?m; a stiffness at a flexural modulus Fmax of 300-2000 mN and Ft of 100-1300 mN; a fracture force F determined by dynamic penetration testing of 200-1500 N; a fracture energy Ws of 2-30 J; a penetration energy Wtot of 2.2-30 J; a film tensile stress at 15% longitudinal and transverse elongation of 9-50 MPa; an Elmendorf longitudinal film tear resistance of 10-60 cN; an Elmendorf transverse film tear resistance of 18-60 cN; a longitudinal film elongation at break of 300-2000%; a transverse film elongation at break of 450-3000%; and a weld seam strength of 25-150 N/15 mm. A method includes filling a bag with polysilicon, and welding by pulse sealing with contact pressure greater than 0.01 N/mm2 to obtain a 25-150 N/15 mm weld seam strength.

Abstract: The present invention relates to polycrystalline silicon chunks which are cubic and have a metal content of less than 200 pptw and a dopant content of less than 50 ppta. Methods for producing polycrystalline silicon chunks, include the steps of providing a polycrystalline silicon rod, comminuting the polycrystalline silicon rod into cubic chunks, and cleaning the polycrystalline silicon chunks, wherein comminution takes place using a spiked-roll crusher having at least one spiked roll, the spiked roll including W2C phases or WC phases with 0.1-10% of a metal carbide selected from the group consisting of titanium carbide, chromium carbide, molybdenum carbide, vanadium carbide, and nickel carbide or consisting of steel with 1-25% W.

Abstract: The invention provides a process for determining surface contamination of polycrystalline silicon, including the steps of: a) providing two polycrystalline silicon rods by deposition in a Siemens reactor; b) determining contaminants in the first of the two rods immediately after the deposition; c) conducting the second rod through one or more systems in which polycrystalline silicon rods are processed further to give rod pieces or polysilicon fragments, optionally cleaned, stored or packed; d) then determining contaminants in the second rod; wherein the difference in the contaminants determined in the first and second rods gives surface contamination of polycrystalline silicon resulting from systems and the system environment.

Abstract: Disclosed is a process for cleaning polycrystalline silicon chunks in an acidic cleaning bath, wherein: (a) the cleaning includes several cleaning cycles, (b) a particular amount of acid is consumed in each cycle, (c) a computer-controlled dosage system integrator adds up those amounts of acid consumed in each cycle to give a current total consumption of acid in the bath, and (d) on attainment of a total consumption of acid in the bath corresponding to an optimal dosage of the dosage system, the dosage system supplies this optimal dosage of unconsumed acid withdrawn from a reservoir vessel to the bath. Another process for cleaning polycrystalline silicon chunks in an acidic cleaning bath includes an acid circuit in which acid is circulated, wherein the ratio of amount of acid circulated in liters to the mass of polysilicon chunks present in the bath in kg is greater than 10.

Abstract: The invention relates to a method for producing thin silicon rods (1), including the steps: a) providing a rod of polycrystalline silicon, from which at least two thin rods (11, 12) with a reduced cross section in comparison with the polycrystalline silicon rod are separated; b) cleaning the at least two separated thin rods (11, 12) by treatment with a material-eroding liquid medium; c) welding at least two of the cleaned thin rods (11, 12) to form a longer thin rod (1); and d) packaging the longer thin rod (1) in a tubular film (100).

Abstract: Polysilicon is freed of metallic impurities without the use of HCl or H2O2 by a preliminary cleaning with NHO3, HF, and H2SiF6 and a main cleaning with HNO3 and HF, followed by hydrophilization. The main cleaning solution can be cycled to the process as a preliminary cleaning solution component.

Abstract: A breathable polyethylene glove as an overglove, over a cut- and puncture-resistant and nonfuzzing underglove, is useful for the non-contaminating packing of high-purity silicon, such as chunk polysilicon and silicon wafers.

Abstract: In a method for recovering acid from an aqueous etching mixture containing HF, HNO3, H2SiF6 and HNO2 which has been used for purifying polycrystalline silicon, the used etching mixture is distilled progressively so that approximately from 20 to 50 wt. % of the mixture is distilled off as dilute acid containing more than 90 wt. % of the silicon dissolved as hexafluorosilicic acid in a first fraction, and the water contained in the used etching mixture having been reduced by approximately 10-30 wt. %, this water-depleted mixture is then concentrated by evaporation to a residue of about 1 to 5 wt. % of the initial amount of used etching mixture during which a second fraction is distilled off, and the residue is disposed of.