Abstract: The present disclosure generally relates to semiconductor device fabrication and integrated circuits. More particularly, the present disclosure relates to methods of forming a two-part trench in a semiconductor device that includes one or more field-effect transistors (FETs). The present method includes forming a semiconductor layer above a substrate, forming a mask layer above the semiconductor layer, forming a mask opening with sidewalls in the mask layer and exposing the semiconductor layer, depositing a profile control layer on the sidewalls of the mask opening, and forming a trench in the semiconductor layer by simultaneously etching the profile control layer and the exposed semiconductor layer, where the etching of the profile control layer forms the trench with top and bottom sections having different widths.