Manufacturing method for semiconductor device and semiconductor device

Abstract

A trench is formed on a semiconductor substrate with a first insulation film patterned on the semiconductor substrate as a mask; a second insulation film is embedded in the trench and flattened; an upper portion of the first insulation film is selectively removed, and a part of a side face of the second insulation film is exposed; a part of the second insulation film is isotropically removed; a lower portion of the remaining first insulation film is selectively removed; and then a part of the remaining second insulation film is further isotropically removed so that an upper face of the second insulation film is at a predetermined height from a surface of the semiconductor substrate, a taper having a minimum taper angle of 90° or more is formed on the side face of the second insulation film, and a STI is formed.

Dependencies are inferred from the claim text.