A transistor includes a trench formed in a semiconductor substrate. A gate electrode is formed in the trench with a first edge of the gate electrode proximate to a first sidewall of the trench. A first field plate is formed in the trench with the first field plate located between a second edge of the gate electrode and a second sidewall of the trench. A dielectric material is formed in the trench with the dielectric material having a first thickness between the first sidewall and a first edge of the first field plate, and a second thickness between the second sidewall and a second edge of the first field plate, the second thickness larger than the first thickness.