| 摘要 |
A semiconductor device and a method for manufacturing the same are provided to realize a high device isolation characteristic in a miniaturized NAND flash memory. A semiconductor device includes a plurality of memory cells. The plurality of memory cells are arranged in the shape of a matrix in a first direction of a main surface of a semiconductor substrate(1) of a first conductive type and in a second direction orthogonal to the first direction. The memory cell has a floating gate(5) formed on the main surface of the semiconductor substrate(1) through a gate insulating film(4), and a control gate(8) formed on the floating gate(5) through an insulating film(6). The control gate(8) of the memory cell arranged in the first direction forms a word line(WL) extended in the first direction. The plurality of memory cells arranged in the second direction are connected in series. The memory cells adjacent in the first direction are separated from each other by a device isolation trench(3) formed on the main surface of the semiconductor substrate(1) and extended in the second direction. The diameter of the device isolation trench(3) of the first direction at the bottom is larger than the diameter at the surface of the semiconductor substrate(1).
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