Semiconductor device and methods of formation

Abstract

A high voltage transistor may include a stepped dielectric layer between a field plate structure and a channel region of the high voltage transistor in a substrate. The stepped dielectric layer may increase the breakdown voltage of the high voltage transistor by reducing the electric field strength near the drain region of the high voltage transistor. In particular, a portion of the stepped dielectric layer near the drain region includes a thickness that is greater relative to a thickness of another portion of the stepped dielectric layer near the gate structure. The increased thickness near the drain region provides increased electric field suppression near the drain region (which operates at high voltages). In this way, the stepped dielectric layer enables the high voltage transistor described herein to achieve higher breakdown voltages without increasing the distance between the gate structure and the drain region of a high voltage transistor.