Patent ID: 9126242
Filing Date: 2015-09-08
Classification: B08B,C01B,C23C,F26B,F28G

Abstract:
1. A method for producing polycrystalline silicon, said method comprising: repeating a plurality of times a precipitation of polycrystalline silicon by the Siemens method in a bell jar, wherein after completion of precipitation of a batch of polycrystalline silicon and before a precipitation of a next batch of polycrystalline silicon, cleaning said bell jar by the following method of cleaning a bell jar: washing said bell jar by contacting water with an inside of said bell jar; and then drying said bell jar by reducing a pressure inside of said bell jar to a pressure of 1000 Pa or less to remove moisture, using a vacuum pump capable of achieving 200 Pa or less; and then introducing a high purity inert gas having a dew point of −40° C. or less into said bell jar to return the pressure inside of said bell jar to atmospheric pressure, wherein a time from completion of the washing to completion of the drying is 1.2 hours or less, to obtain polycrystalline silicon having an electric resistivity of 1500 Ω·cm or more.