Patent ID: 6303410
Filing Date: 2001-10-16
Classification: H01L

Abstract:
A method of forming a semiconductor switching device, comprising the steps of:forming a semiconductor substrate having a drift region of first conductivity type therein extending adjacent a face thereof;forming a trench in the substrate, said trench having a bottom that extends adjacent the drift region and a sidewall that extends to the face;forming a gate electrode insulating layer in the trench;forming a conductive layer on the substrate, said conductive layer extending opposite a first portion of the face that intersects the sidewall of the trench and onto the gate electrode insulating layer in the trench;patterning the conductive layer to define a T-shaped gate electrode that fills the trench and also extends opposite the first portion of the face; andforming emitter and base regions of first and second conductivity type, respectively, that are self-aligned to the T-shaped gate electrode and extend in the drift region, by:implanting emitter and base region dopants into the face using the T-shaped gate electrode as an implant mask; and thensimultaneously laterally diffusing the implanted emitter and base region dopants into the drift region for a sufficient duration so that the base region extends to and along the first portion of the face and also extends to and along an upper portion of the sidewall of the trench and the source region extends underneath an edge of the T-shaped gate electrode but does not extend to an intersection between the sidewall of the trench and the first portion of the face.