Low resistance contact structure for a select transistor of eeprom memory cells in a no-dpcc process

Abstract

A semiconductor memory device having at least one memory cell row, each memory cell having an information storing element and a related select transistor for selecting the storing element. The select transistor includes a gate oxide region over a silicon substrate, a lower polysilicon layer and an upper polysilicon layer superimposed to the gate oxide region and electrically insulated by an intermediate dielectric layer interposed therebetween. The gate oxide regions of the select transistors of the at least one row are separated by field oxide regions, and the lower and upper polysilicon layers and the intermediate dielectric layer extend along the row over the gate oxide regions of the select transistors and over the field oxide regions. Along the row there is at least one opening in the upper polysilicon layer, intermediate dielectric layer and lower polysilicon layer, inside of which a first contact element suitable to electrically connect the lower and upper polysilicon layers is inserted.