Enhanced RESURF HVPMOS device with stacked hetero-doping RIM and gradual drift region

摘要

An HV PMOS device formed on a substrate having an HV well of a first polarity type formed in an epitaxial layer of a second polarity type includes a pair of field oxide regions on the substrate and at least partially over the HV well. Insulated gates are formed on the substrate between the field oxide regions. Stacked hetero-doping rims are formed in the HV well and in self-alignment with outer edges of the gates. A buffer region of the first polarity type is formed in the HV well between and in self-alignment with inner edges of the gates. A drift region of the second polarity type is formed in the buffer region between and in self-alignment with inner edges of the gates. The drift region includes a region having a gradual dopant concentration change, and includes a drain region of the second polarity type.