US Patent 10355110 FinFET and method of forming same

A method includes forming a first active fin structure and a second active fin structure on a substrate. A dummy fin structure is formed on the substrate, the dummy fin structure being interposed between the first active fin structure and the second active fin structure. The dummy fin structure is removed to expose a first portion of the substrate, the first portion of the substrate being disposed directly below the dummy fin structure. A plurality of protruding features is formed on the first portion of the substrate. A shallow trench isolation (STI) region is formed over the first portion of the substrate, the STI region covering the plurality of protruding features, at least a portion of the first active fin structure and at least a portion of the second active fin structure extending above a topmost surface of the STI region.