| 摘要 |
PROBLEM TO BE SOLVED: To provide a technology that can improve the reliability of a nonvolatile memory, while allowing to reduce occupied area of the nonvolatile memory. SOLUTION: A code flash memory cell is made different in structure from a data flash memory cell. Specifically, reading speed is improved by employing a structure where a memory gate electrode 22a is formed only on a sidewall at one side of a control gate electrode 14a as a structure for the code flash memory cell. For the data flash memory cell, on the other hand, memory gate electrodes 22b, 22c are formed on sidewalls at both sides of the control gate electrode 14b. That is, by changing the data flash memory cell from a binary memory cell to a multi-value memory cell, deterioration in the retention characteristics is prevented to achieve the high-reliability data flash memory cell, while reducing occupied area of the data flash memory cell. COPYRIGHT: (C)2009,JPO&INPIT
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