Thin poly field plate design

Abstract

The present disclosure relates to a high voltage transistor device having a thin polysilicon film field plate, and an associated method of formation. In some embodiments, the high voltage transistor device has a gate electrode disposed between source and drain regions and separated from a substrate by a gate dielectric. A spacer is disposed along an upper surface of the substrate. The spacer extends along a first gate sidewall closer to the drain region, crosses over an upper edge of the gate electrode, and further extends laterally to cover a portion of an upper surface of the gate electrode. A field plate including a polysilicon thin film is disposed along upper and sidewall surfaces of the spacer so that the polysilicon thin film is separated from the gate electrode and the substrate by the spacer. The thin polysilicon film field plate improves the breakdown voltage of the transistor device.