| 摘要 |
PROBLEM TO BE SOLVED: To provide a nonvolatile semiconductor storage device in which a write characteristic of a memory cell is improved by preventing a threshold of a selection gate transistor from lowering. SOLUTION: The nonvolatile semiconductor storage device having a plurality of NAND strings, wherein each of the NAND strings comprises: a memory cell block to which a plurality of nonvolatile memory cells are serially connected; a first selection gate transistor connected to a data transfer line contact; and a second selection gate transistor connected to a source line contact. The height of the upper surface of an element separation insulating film 24 between an adjacent data transfer line contacts is higher than that of the main surface of a semiconductor substrate 23 in an element region between the first selection gate transistor and data transfer line contact. Alternatively, the height of the upper surface of the element separation insulating film 24 between the adjacent source line contacts is higher than that of the main surface of the semiconductor substrate 23 in an element region between the second selection gate transistor and source line contact. COPYRIGHT: (C)2007,JPO&INPIT
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