Extended drain self-aligned silicon gate MOSFET

In an improved extended drain field effect transistor of the type including a body of semiconductor material in which spaced drain and source regions of a first conductivity type, with a given concentration of conductivity modifiers, are embedded at the surface of the body, the drain and source regions spaced a given distance one from the other to define the channel region, a first layer of insulating material disposed over the channel region, and a gate member disposed on the first insulating layer over the channel region, the improvement comprising:

• the portion of the channel region adjacent the source region having a second conductivity type opposite the first conductivity type;
• the remainder of the channel region, adjacent the drain region, forming a drift region of the first conductivity type with a lower concentration of conductivity modifiers therein than the drain and source regions;
• and
• the gate member is disposed solely over the channel region with the edges thereof in alignment with respective edges of the source and drift regions.