Method of making a trench gate complimentary metal oxide semiconductor transistor

Claim 1

A method of forming a trench gate complimentary metal oxide semiconductor transistor comprising: forming a trench within a semiconductor substrate, the semiconductor substrate being doped to a first conductivity type; after forming said trench, forming a first layer doped to a second conductivity type opposite to the substrate on the surfaces of the trench, said first layer having a thickness less than the depth of said trench; applying a layer of insulator about the surfaces of the trench and upon said first layer; doping a first region and a second region adjacent the trench to a second conductivity type; doping upper segments of said first and second regions to the same conductivity type as the substrate, said segments being isolated from the substrate by said first and second regions; and applying a layer of conductive gate material within said trench upon said layer of insulator; wherein said first and second segments form the source and drain, respectively, of the transistor, and said first layer extends between said source and drain about said trench, and wherein said gate material is isolated from said first layer by said layer of insulator; and wherein forming said first layer such that it has a thickness less than the depth of the trench eliminates the need for deep diffusion.

Claim 2

A method of forming a trench gate complimentary metal oxide semiconductor transistor comprising: forming a trench within a semiconductor substrate, the semiconductor substrate being doped to a first conductivity type; after forming said trench, forming a first layer doped to a second conductivity type opposite to the substrate on the surfaces of the trench, said first layer having a thickness less than the depth of said trench; applying a layer of insulator about the surfaces of the trench and upon said first layer; doping a first region and a second region adjacent the trench to a second conductivity type; doping upper segments of said first and second regions to the same conductivity type as the substrate, said segments being isolated from the substrate by said first and second regions; and applying a layer of conductive gate material within said trench upon said layer of insulator; wherein said first and second segments form the source and drain, respectively, of the transistor, and said first layer extends between said source and drain about said trench, and wherein said gate material is isolated from said first layer by said layer of insulator; and wherein forming said first layer such that it has a thickness less than the depth of the trench eliminates the need for deep diffusion.