Carbon monoxide concentrations in a Czochralski growth furnace

Abstract

High-performance power devices require silicon crystals with long minority carrier lifetimes and, subsequently, low carbon concentrations. This paper reports in-situ measurements of carbon monoxide (CO) in a Czochralski growth furnace used for the growth of single-crystal silicon. During the heating and melting processes, the major causes of CO gas generation are (i) outgassing from carbon parts inside the furnace, (ii) reactions between the quartz and carbon crucible, and (iii) reactions between the silicon melt and quartz crucible. By conducting heating experiments with and without polysilicon and quartz crucibles, we successfully measured the independent CO generation contributions of causes (i), (ii), and (iii) listed above. The outgassing process generated CO gas during the heating process of the raw material. CO generated during the melting process of the raw material was attributed to reactions between (ii), the quartz and carbon, and (iii), the silicon melt and carbon parts, which occurred after CO outgassing from carbon parts in the furnace.