Residual gas recovery in silicon deposition by thermal decomposition - by condensing chloro-silane cpds. and freezing hydrogen chloride, leaving purified hydrogen

摘要

In the recovery of unused residual gases from a mixt. of chlorosilanes (I), H2 and HCl obtd. in the deposition of Si by thermal decompsn. of a gas mixt. of (I) and H2, (I) are condensed at a temp. between the b. pt. of (I) and the b. pt. of HCl and then HCl is frozen out at a temp. below its m. pt. Pref. (I) are condensed out at max. -100 degrees C and then distilled. The HCl is frozen out at min. -150 degrees C using liquid O2, liquid N2 or an electric cooling aggregate. The purified H2 is reused directly n the Si deposition process. Recovery takes place at min. technical cost.