Process for forming a field isolation structure and gate structures in integrated misfet devices

Claim 1

A process for forming a field isolation structure of integrated devices, consituted by a dielectric layer formed over a region of a semiconducting substrate having an increased superficial doping level, for isolating active areas geometrically defined on the surface of said semiconducting substrate by said field isolation structure, and gate structures functionally disposed in respective active areas and constituted by an electrically connectable layer of conducting material electrically isolated from said semiconducting substrate by a dielectric gate layer, characterized by comprising the following steps: a) forming a dielectric gate layer on the surface of a monocrystalline semiconducting substrate; b) depositing a first layer of a first conducting material; c) masking the active areas by a first masking photoresist structure; d) etching at least said first layer of said first conducting material in unmasked areas, leaving portions of said first conducting layer in said masked active areas; e) optionally implanting a dopant for increasing the superficial doping level of said semiconducting substrate in said etched areas; f) removing said first masking photoresist structure; g) conformally depositing a layer of a field isolation dielectric material for a thickness substantially equal to the thickness of said portions of said first conducting layer masking said active areas; h) depositing a layer of a planarization material; i) etching-back said planarization material until exposing the peaks of the said masking portions of said first conducting layer; j) depositing a second layer of said first conducting material in electrical continuity with said portions of said first layer of conducting material; k) forming a second masking photoresist structure for patterning the gate structures of the integrated devices; l) selectively etching said first conducting material belonging to said second and to said first layers and removing it completely from unmasked areas.