Fabrication of power field effect transistors and the resulting structures

摘要

The fabrication method provides a power metal-oxide-semiconductor field-effect transistor (MOSFET) having high switching speed capabilities. The high switching speed is facilitated by narrow channel length which is defined by the difference in lateral diffusion junctions of the P substrate and N source diffusions. The high current capability is produced by the large channel width. The high voltage capability is caused by the use of FET substrate P diffusions designed to be located apart from one another by very small distances. Unbiased or floating P diffusions are designed to flank the outer peripheries of P substrate diffusions. The close proximity of the adjacent P substrate diffusions reduces the electric field in the curvature portion of the P diffusion junctions in the N- silicon body at their inner peripheries, while the presence of the unbiased P diffusions at the appropriate distance from the outer peripheries of P substrate diffusions reduces the electric field in the curvature region of the P substrate diffusions at their outer peripheries. The N silicon body forms the drain region.