Non-volatile sonos-type memory device
AssigneeSpansion LLC
InventorHiroyuki Nansei
Life of this patent
Estimating the term…
Abstract
A semiconductor memory device with the thickness of both a tunnel film and a top film provided thereon configured to be in the FN tunneling region (4 nm or more). Data retention characteristics can be improved by configuring both a tunnel film and a top film to have a thickness in the FN tunneling region. Secondly, a high-concentration impurity region of a conductivity type the same as that of the substrate is provided in a substrate region arranged between assist gates provided adjacently to each other. The aforementioned high-concentration impurity region makes a depletion layer extremely thin when bias is applied to the assist gates. Hot holes generated between bands in the depletion region are injected into a charge storage region and the holes and electrons make pairs and disappear, enabling easy data erasing.
Claims17
A method of fabricating a semiconductor device comprising the steps of:
- forming assist gates on a gate insulating film on a semiconductor substrate of a chosen conductivity type;
- forming a high-concentration impurity region in the semiconductor substrate and located predominantly between adjacent assist gates, the high-concentration impurity region having the same conductivity type as that of the semiconductor substrate, wherein portions of the high-concentration impurity region underlie the adjacent assist gates;
- and
- forming a charge storage region above the semiconductor substrate and composed of at least a tunnel oxide film and a storage film.
Dependencies are inferred from the claim text.