NONVOLATILE SEMICONDUCTOR STORAGE DEVICE

摘要

[PROBLEMS] To provide a split-gate type nonvolatile semiconductor storage device which has a large read current and performs high-speed operation. [MEANS FOR SOLVING PROBLEMS] A nonvolatile semiconductor storage device is provided with first and second gate electrodes extending parallel to each other; a first gate insulating film, which is formed between the first gate electrode and a semiconductor substrate and does not include a charge accumulating layer; and a second gate insulating film, which is formed between the first gate electrode and the second gate electrode and between the second gate electrode and the semiconductor substrate, and includes the charge accumulating layer. The side surface of the first gate electrode adjacent to the second gate electrode has a protruding section which protrudes toward the second gate electrode from the bottom portion adjacent to the semiconductor substrate.