Process for regenerating unreacted chlorosilanes and unreacted hydrogen in the production of polycrystalline semiconductor silicon

摘要

The present invention relates to a process for producing polycrystalline semiconductor silicon, in particular a process for utilising waste products produced in the production of polycrystalline semiconductor silicon. The process for regenerating unreacted chlorosilanes and unreacted hydrogen in the production of polycrystalline semiconductor silicon comprises condensing the chlorosilanes in stages in a temperature range from -15 to -90 DEG C, employing at least four stages, with a constant temperature at each condensation stage; the hydrogen is then regenerated by freezing out the chlorosilanes and the hydrogen chloride in at least three stages, at a freezing-out temperature of -120 to -125 DEG C at stage 1 and of -150 to -165 DEG C at stage 2, and the abovementioned substances are frozen out at stage 3 at a temperature which is above the vaporisation point of liquid nitrogen.