A method of forming a semiconductor structure includes forming a plurality of fins over a substrate, at least a portion of one or more of the fins providing one or more channels for one or more fin field-effect transistors. The method also includes forming a plurality of active gate structures over the fins, forming at least one single diffusion break trench between a first one of the active gate structures and a second one of the active gate structures, and forming at least one double diffusion break trench between a third one of the active gate structures and a fourth one of the active gate structures. The double diffusion break trench has a stepped height profile in the substrate, the stepped height profile comprising a first depth with a first width and a second depth less than the first depth with a second width greater than the first width.