Abstract
The structure of a thin (10 nm) oxide, grown in micron‐sized trenches in silicon, has been studied by high resolution electron microscopy (HREM). The trenches were produced in {100} wafers by dry etching, and have {110} sidewalls and {100} bottom surfaces. Oxidation was carried out at 1125°C by rapid thermal annealing in pure, dry 
to produce a nominal 10 nm oxide on the top wafer surface. It is found that the oxide is largely smooth and continuous, with minimal 
protrusions. However, the oxide thickness varies significantly around the trench, being thickest at the {110} sidewalls and thinnest in the inner, concave corners. In addition the latter are distinctly faceted on {111} and {311} planes. It is thought that crystallography plays an important role in the variation of trench structure after oxidation.