| 摘要 |
PURPOSE: To resolve problems where the reliability of a tunnel oxide film is low by an electric field convergence at a trench edge and a process becomes complicated when a floating gate electrode is formed in a two-layer structure in order to realize a high capacity ratio, in a flash memory where the trench self-aligned in a laminated layer pattern is used to isolate an element and cell intervals can be minimized, which is very useful for making a memory cell a high density. CONSTITUTION: A layered structure body is formed on an active gate film region of a semiconductor substrate 1 and a gate film 30 which is located on the groove isolation side of the active gate film 2 is made thick, and then the groove isolation region is formed for the layered structure body in a self-aligned manner. As a result, the distance between an edge part of the groove 11 and the floating gate electrode 3 can be increased, and thus a negative influence to device property due to the electric field convergence in the edge part of the groove in a device operation can be eliminated.
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