Thin dielectric degradation during silicon selective epitaxial growth process

Abstract

A fundamental issue in silicon selective epitaxial growth (SEG) processes is the impact of the pre-epitaxy silicon surface treatments and the SEG ambient on the properties of thin insulating materials exposed to the preclean environment. In this study, we compare pinhole formation in 10–50 nm thermal oxides with more robust oxide/nitride composites of similar thickness. The degradation of thin thermal oxide is attributed to pinhole formation and expansion in the ultrathin oxide layers during ex situ pre-epi surface treatments, in situ H2 prebake, and selective epitaxial deposition process. The superior resistance of oxide/nitride/oxide (ONO) structures to dielectric degradation may be attributed to the existence of the sandwiched silicon nitride layer which suppresses the mechanism of oxide decomposition during the pre-epitaxy wet cleaning, and the selective epitaxial growth processes.