High-Voltage MOSFET with High Breakdown Voltage and Low On-Resistance and Method of Manufacturing the Same

摘要

A high-voltage transistor is formed in a deep well of a first conductivity type that has been formed in a semiconductor substrate or epitaxial layer of a second conductivity type. A body region of the second conductivity type is formed in the deep well, into which a source region of the first conductivity type is formed. A drain region of the first conductivity type is formed in the deep well and separated from the body region by a drift region in the deep well. A gate dielectric layer is formed over the body region, and a first polysilicon layer formed over the gate dielectric layer embodies the gate of the transistor. The field plate dielectric layer is formed over the drift region after the gate has been formed. Finally, the field plate dielectric is covered by a second polysilicon layer having a field plate positioned over the field plate dielectric layer in the drift region.