Floating gate memory fabrication methods comprising a field dielectric etch with a horizontal etch component

摘要

A silicon nitride layer (120) is formed over a semiconductor substrate (104) and patterned to define isolation trenches (130). The trenches are filled with dielectric (210). The nitride layer is removed to expose sidewalls of the trench dielectric (210). The dielectric is etched to recess the sidewalls away from the active areas (132). Then a conductive layer (410) is deposited to form floating gates for nonvolatile memory cells. The recessed portions of the dielectric sidewalls allow the floating gates to be wider at the top. The gate coupling ratio is increased as a result. Other features are also provided.