Closed loop process for producing polycrystalline silicon and fumed silica
AssigneeMEMC Electronic Materials, Inc.
InventorJohn P. DeLuca
Life of this patent
Estimating the term…
Abstract
A closed loop process for producing electronic grade polycrystalline silicon from silane and fume silica from silicon tetrachloride comprises the steps of: (a) subjecting impure silicon to hydrochlorination with hydrogen chloride to produce trichlorosilane and silicon tetrachloride together with minor amounts of dichlorosilane and monochlorosilane; (b) converting the trichlorosilane to silicon tetrachloride and silane; (c) converting the silane to polycrystalline silicon and hydrogen; (d) reacting the silicon tetrachloride from steps (a) and (b) with hydrogen and oxygen to produce fume silica and hydrogen chloride, and (e) recycling the hydrogen chloride from step (d) for use in step (a).
Claims5
A closed loop process for producing electronic grade polycrystalline silicon from silane and fumed silica from silicon tetrachloride comprising the steps of:
- a) subjecting impure silicon to hydrochlorination with hydrogen chloride to produce trichlorosilane and silicon tetrachloride together with minor amounts of dichlorosilane and monochlorosilane;
- b) converting said trichlorosilane to silicon tetrachloride and silane;
- c) converting said silane to polycrystalline silicon and hydrogen;
- d) reacting the silicon tetrachloride from steps a) and b) with hydrogen and oxygen to produce fumed silica and hydrogen chloride;
- and
- e) recycling the hydrogen chloride from step d) for use in step a).
Dependencies are inferred from the claim text.