A semiconductor device is formed on a semiconductor layer. A gate dielectric layer is formed over the semiconductor layer. A layer of gate material is formed over the gate dielectric layer. The layer of gate material is patterned to form a gate structure. Using the gate structure as a mask, an implant into the semiconductor layer is performed. To form a first patterned gate structure and a trench in the semiconductor layer surrounding a first portion and a second portion of the semiconductor layer and the gate, an etch through the gate structure and the semiconductor layer is performed. The trench is filled with insulating material.