| 摘要 |
PURPOSE:To make it possible to remove B by oxidation and to obtain high purity by oxidizing the surface of raw material silicon powder to form prescribed SiO2, then irradiating the SiO2 with an electron beam under a reduced pressure, thereby dissolving the silicon. CONSTITUTION:Metallic silicon having about 1.5mm average grain size is charged at about 1.5kg into a quartz reaction tube internally having a screw made of quartz and >=1 kinds of gases selected from a group of O2, H2O and CO2 are introduced together with gases contg. 1 to 20vol.% gaseous Ar or N2 into this reaction tube where the gases are heated and oxidized for about two hours at 600 to 1000 deg.C. The silicon formed with the SiO2 on the surface of the silicon powder at 1.5 to 15kg as the weight of the SiO2 per 1kg is obtd. This silicon is then charged into a copper crucible cooled with water and is dissolved by irradiation with the electron beam of about 30KW beam output under a vacuum, by which the B is oxidized away and the refined silicon of <6ppm B in the silicon is obtd. |
