US Patent 7232726 Trench-gate semiconductor device and method of manufacturing

Consistent with an example embodiment a trench-gate semiconductor device, for example a MOSFET or IGBT, having a field plate provided below the trenched gate is manufactured using a process with improved reproducibility. The process includes the steps of etching a first grove into the semiconductor body for receiving the gate, and etching a second groove into the top major surface of the semiconductor body, the second groove extending from the first groove and being narrower than the first groove. The invention enables better control of the vertical extent of the gate below the top major surface of the semiconductor body.