Method for producing highest-purity silicon for electric semiconductor devices

Claim 1

IN A METHOD OF PRODUCING SILICON OF HIGH PURITY, FOR USE IN ELECTRICAL SEMICONDUCTING DEVICES, IN WHICH METHOD SILICON IS PRECIPITATED ONTO A HOT CARRIER BODY OF SILICON BY GAS-PHSES CHEMICAL CONVERSION OF A HALOGEN COMPOUND OF SILICON BY CONTACT THEREOF WITH THE HOT BOODY, THE IMPROVEMENT COMPRISIING CARRYING OUT SAID METHOD IN AN AT LEAST PARTLY TRANSPARENT REACTION VESSEL AT LEAST PARTLY COMPRISED OF A SILICEOUS MATERIAL OF THE GROUP CONSISTING OF GLASS AND QUARTZ, THE HOT BODY BEING HEATED TO ABOUT 1100* TO 1200* C. BY PASSAGE OF AN ELECTRIC CURRENT THERETHROUGH, AND MAINTAINING THE TEMPERATURE OF THE INNER WALLS OF THE VESSEL AT BETWEEEN ABOUT 300*C. AND 800*C. DURING THE PRECIPITATION PERIOD, TO MINIMIZE FORMATION OF A COATING OF HIGH MOLECULAR WEIGHT SILICON HALOGENIDE ON THE SURFACE OF THE REACTION VESSEL.