초록 ▼

Disclosed is the memory cell of an EEPROM having a p-type silicon substrate and a floating gate formed on this silicon substrate via a tunnel oxide film. The element region set in the silicon substrate projects from the surface of a trench-type element isolation region. The projecting element region

Disclosed is the memory cell of an EEPROM having a p-type silicon substrate and a floating gate formed on this silicon substrate via a tunnel oxide film. The element region set in the silicon substrate projects from the surface of a trench-type element isolation region. The projecting element region has a curved portion for increasing the density of tunnel electric current, and is rounded to concentrate the tunnel electric current as far as no breakdown occurs in the tunnel oxide film.

대표청구항 ▼

[ We claim:] [1.] A nonvolatile semiconductor memory device comprising:a semiconductor substrate;an element isolation region formed in said substrate;an element region set on a surface of said substrate by the element isolation region to form a memory cell; anda memory cell array prepared by arrayin

[ We claim:] [1.] A nonvolatile semiconductor memory device comprising:a semiconductor substrate;an element isolation region formed in said substrate;an element region set on a surface of said substrate by the element isolation region to form a memory cell; anda memory cell array prepared by arraying a plurality of electrically data erasable memory cells, each memory cell including a tunnel insulating film formed in the element region, a floating gate formed on said tunnel insulating cell, and a control gate capacitively coupled to the element region through said floating gate and said tunnel insulating film,wherein at least part of the element region convexly projects toward said floating gate, and said convexly projecting portion has a curved portion substantially curvedly opposing said floating gate, and a flat portion substantially flatly opposing said floating gate and said tunnel insulating film covers the curved portion and the flat portion.