| 摘要 |
PROBLEM TO BE SOLVED: To reduce shift of threshold value of memory cell due to increase of interference between adjacent floating gates resulting from reduction in width of the word line of a nonvolatile semiconductor storage device, and also to avoid reduction in coupling ratio generated by difficulty of simultaneous processing of control gate material, interlayer insulating film material and floating gate material. SOLUTION: A concave floating gate is formed by embedding the floating gate formed of a thin polysilicon material to a space of stripe pattern of the third gate or insulating film. A higher insulating film pattern for isolating memory cells is formed by utilizing a dummy pattern stripe in the vertical direction perpendicular to the line and space of the third gate or insulating film which is higher than the floating gate. Accordingly, the shape in which the floating gate is perfectly embedded and isolated can be formed. COPYRIGHT: (C)2004,JPO&NCIPI
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