SEMICONDUCTOR MEMORY DEVICE AND MANUFACTURE THEREOF

摘要

PROBLEM TO BE SOLVED: To provide a semiconductor memory device and a manufacture thereof capable of finely patterning a polycrystalline silicon film without a portion not being left, and of easily preventing dielectric strength between an erasable electrode and a floating gate electrode. SOLUTION: The manufacture of a semiconductor memory device includes a process of forming a floating gate electrode 15 by etching away a conductive film 8 with the use of a sidewall insulating film 14 along the side of a control gate electrode 13, as a mask is constituted by anisotropically dry-etching the conductive film 8 under the condition of a high selective etching ratio to an oxide film and then by wet-etching it with an ammonia solution. This semiconductor memory device has a feature in which a trench 19 is formed in a device- isolating insulating film 6 exposed to the side of the floating gate electrode 15.