| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor memory device, which is constituted so as to be capable of enhancing its yield and its reliability by a method, where an irregularity in an operating characteristic caused by an STI step in an STI- structure semiconductor memory device is prevented and the operating characteristic is made uniform, and to provide its manufacturing method. SOLUTION: In this semiconductor memory device and its manufacturing method, a floating gate is formed into a thickness of an extent such that irregularities on the surface of the floating gate caused by an STI step as the positional relationship of a height between the surface of a semiconductor substrate and the surface of an STO-structure element isolation region are embedded, in other words, in thickness to such an extent that the area on the surface of the floating gate becomes nearly constant, irrespective of the height of the STI step, more correctly, in thickness of 1/2 or larger of the distance between STI-structure element isolation regions.
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