Patent ID: 7989890
Filing Date: 2011-08-02
Classification: H01L

Abstract:
1. A semiconductor structure comprising: a semiconductor substrate; a pre-high-voltage well (pre-HVW) in the semiconductor substrate, wherein the pre-HVW is of a first conductivity type; a high-voltage well (HVW) over the pre-HVW, wherein the HVW is of the first conductivity type, and wherein the HVW has a higher impurity concentration than the pre-HVW; a field ring in the HVW and occupying a top portion of the HVW, wherein the field ring is of a second conductivity type opposite the first conductivity type; an insulation region over and in contact with the field ring and a portion of the HVW; a gate electrode partially over the insulation region; a drain region in the HVW, wherein the drain region is of the first conductivity type, and wherein the HVW horizontally extends further toward the drain region than the pre-HVW; and a source region adjacent to, and on an opposite side of the gate electrode than the drain region.