Defects Induced by Carbon Contamination in Low-Temperature Epitaxial Silicon Films Grown with Monosilane

The structures of the defects induced by carbon contamination in epitaxial silicon films grown with monosilane (SiH4) on silicon substrates were investigated. A new formation mechanism of defects associated with carbon in silicon epitaxial growth processes is proposed. The carbon contaminants were introduced prior to the growth by chemical vapor deposition (CVD), where the growth chamber was intentionally contaminated with organic materials. The carbon contaminant concentration was changed by adjusting the annealing conditions at temperatures ranging from 900°C to 1100°C. Silicon epitaxial films were grown by CVD at a temperature of 700°C. In this experiment, we found that pits were formed as dominant surface defects under the condition of a relatively low carbon concentration of less than 4.5×1013 cm-2, while mound defects were formed at a carbon concentration of more than 4.5×1013 cm-2. These defects can be explained by the formation of silicon carbide (SiC) islands resulting from the carbon contamination.