Oxide-rich liner layer for flowable CVD gapfill

摘要

The formation of a gap-filling silicon oxide layer with reduced volume fraction of voids is described. The deposition involves the formation of an oxygen-rich less-flowable liner layer before an oxygen-poor more-flowable gapfill layer. However, the liner layer is deposited within the same chamber as the gapfill layer. The liner layer and the gapfill layer may both be formed by combining a radical component with an unexcited silicon-containing precursor (i.e. not directly excited by application of plasma power). The liner layer has more oxygen content than the gapfill layer and deposits more conformally. The deposition rate of the gapfill layer may be increased by the presence of the liner layer. The gapfill layer may contain silicon, oxygen and nitrogen and be converted at elevated temperature to contain more oxygen and less nitrogen. The presence of the gapfill liner provides a source of oxygen underneath the gapfill layer to augment the gas phase oxygen introduced during the conversion.