Flash memory cell with self-aligned tunnel dielectric area above LDD structure

DETAILED DESCRIPTION What is claimed is: 1.
An improved memory cell, comprising: a semiconductor substrate; source and drain regions formed in said semiconductor substrate; a gate dielectric formed on said semiconductor substrate; a first gate electrode with sidewalls formed on said gate dielectric; a sidewall oxide layer formed on said sidewalls of said first gate electrode; a lightly doped region formed in said semiconductor substrate between said source region and said first gate electrode; a tunnel oxide layer having a width formed over said lightly doped region, wherein said width is the distance between said source region and the nearest said sidewall oxide layer; a first oxide layer formed over said source and drain regions; a second gate electrode formed on said semiconductor substrate over said first gate electrode, said sidewall oxide layer, said tunnel oxide layer, and said first oxide layer so as to make electrical contact between said first gate electrode and said second gate electrode; a layer of oxide/nitride/oxide formed on said semiconductor substrate over said second gate electrode; a control gate electrode formed on said layer of oxide/nitride/oxide; a floating gate formed from said first gate electrode and said second gate electrode; an insulating dielectric layer formed on said semiconductor substrate over said control gate electrode; contact openings formed in said insulating dielectric layer; metal contacts formed in said contact openings formed in said insulating dielectric layer; a patterned metal conductor layer formed over said insulating dielectric layer; and a passivation dielectric layer formed over said insulating dielectric layer covering said patterned metal conductor layer and said metal contacts.
2.
The improved memory cell of claim 1 wherein said semiconductor substrate is a P type silicon substrate.
3.
The improved memory cell of claim 1 wherein said first gate electrode is polysilicon with a thickness of between about 1000 Angstroms and 5000 Angstroms