Methods of forming insulated-gate semiconductor devices using

Abstract

A method of forming an insulated gate semiconductor device includes the steps of patterning an insulated gate electrode on a face of a substrate containing a first conductivity type region and forming a trench at the face using the gate electrode as a mask. Second conductivity type dopants are then deposited onto the bottom and sidewalls of the trench and diffused into the substrate to form a relatively lightly doped first body region. The gate electrode is then used again as a mask during a step of implanting a relatively high dose of second conductivity type dopants at the bottom of the trench. These implanted dopants are then partially diffused laterally and downwardly away from the bottom and sidewalls of the trench. The gate electrode is then used again to deposit first conductivity type dopants onto the sidewalls (and bottom) of the trench. The deposited first conductivity type dopants on the sidewalls and previously partially diffused second conductivity type dopants are then simultaneously diffused into the first body region. During this step, the deposited first conductivity type dopants diffuse laterally away from the sidewalls of trench and underneath the insulated gate electrode into the surrounding first body region to form source regions. The partially diffused second conductivity type dopants also continue to diffuse laterally away from the lowermost portions of the sidewalls of the trench and downward from the bottom of the trench to form a relatively wide second body region underneath the source region(s).