A semiconductor device and method of formation are provided. A semiconductor device includes a first material comprising STI adjacent a fin. The STI is substantially uniform, such that a top surface of the STI has few to no defects and little to no concavity. To form the STI, the first material is implanted with a dopant, which forms an etch stop layer, such that the first material height is reduced by etching rather than CMP. Etching results in a better uniformity of the first material than CMP. STI that is substantially uniform comprises a better current barrier between adjacent fins than a device that comprises STI that is not substantially uniform.