Formation of (111) nanotwin lamellae hillocks in polycrystalline silicon thin films caused by deposition of silicon dioxide layer

Plasma-enhanced chemical vapor deposition was used to deposit layers of tetraethylorthosilicate at different temperatures. In the case of low-temperature deposition (300 °C), the deposited film surface was smooth and the major surface defects of the polycrystalline silicon (poly-silicon) film surface were grooves of grain boundaries. In contrast, in the case of high-temperature deposition (500 °C), the deposited silicon oxide surface exhibited hillocks, and these hillocks were derived from the top end of inclined silicon (111) where protruding nanotwin lamellae penetrated the poly-silicon thin film. The observed hillocks stemming from nanotwin lamellae could have been formed by compressive stress during high-temperature silicon dioxide deposition.