Low on-resistance power mos technology

Abstract

A submicron channel length is achieved in cells having sharp corners, such as square cells, by blunting the corners of the cells. In this way, the three dimensional diffusion effect is minimized, and punch through is avoided. Techniques are discussed for minimizing defects in the shallow junctions used for forming the short channel, including the use of a thin dry oxide rather than a thicker steam thermal over the body contact area, a field shaping p+ diffusion to enhance breakdown voltage, and TCA gathering. Gate-source leakage is reduced with extrinsic gathering on the poly backside, and intrinsic gathering due to the choice of starting material. Five masking step and six masking step processes are also disclosed for manufacturing a power MOSFET structure. This power MOSFET structure has an active region with a plurality of active cells as well as a termination region with a field ring or a row of inactive cells and a polysilicon field plate.