Patent ID: 6057574
Filing Date: 2000-05-02
Classification: H01L

Abstract:
A contactless nonvolatile semiconductor memory device of a virtual ground type, comprising:a semiconductor substrate;a plurality of sub bit lines of the virtual ground type memory, each of said sub bit lines being an impurity diffusion layer in said substrate that has a rectangular shape in plan view with a longer side along a first direction;a plurality of grooves of a rectangular shape in said semiconductor substrate, each of said grooves being between two of said sub bit lines;a first gate insulating layer on said semiconductor substrate at said grooves;a plurality of floating gate electrodes on said first gate insulating layer;a second gate insulating layer on said floating gate electrodes; anda plurality of word lines on said second gate insulating layer, said word lines being along a second direction perpendicular to said first direction, each of said sub bit lines crossing beneath plural said word lines.