Semiconductor device and manufacturing method thereof

Claim 1

A semiconductor device comprising: a semiconductor substrate of one conductivity type; first, second and third recessed portions formed in succession at a predetermined pitch below a surface level of said semiconductor substrate; a first pillarlike remaining region formed between said first and second recessed portions, in which an impurity of an opposite conductivity type is diffused; a second pillarlike remaining region formed between said second and third recessed portions, in which an impurity of said opposite conductivity type is diffused wherein said first and second pillarlike remaining regions are such that their impurity diffused regions extend down to bottom surfaces of respective said recessed portions; a gate region buried in said second recessed portion through an insulating film said gate region comprising: an upper end surface extending to a height of at least the surface level of said semiconductor substrate; and a polysilicon layer on lower and side inner surfaces provided with a tungsten layer thereon, said first and second pillarlike remaining regions being provided with a tungsten layer on each upper surface thereof; and isolation regions buried in said first and third recessed portions.