Impact of CO generation during the melting process on carbon concentration in Czochralski silicon

Abstract

A new carbon contamination model in which carbon monoxide (CO) generated by the chemical reaction between H2O and graphite components during the heating stage can react with the solid-state silicon feedstock was proposed. The influence of CO on carbon concentration during the heating stage in a laboratory-scale Czochralski furnace was investigated using a quadrupole mass spectrometer. A strong peak of CO and H2O partial pressure was observed before the silicon feedstock began to melt. We believe that the purge tube is a major source of CO during the heating stage because carbon contamination of the order of 1016 occurred in the silicon melt by CO generated from the purge tube. Furthermore, we discussed the impact of the SiC film formed on the surface of the silicon feedstock on carbon contamination.