NONVOLATILE SEMICONDUCTOR MEMORY DEVICE AND ITS MANUFACTURING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a nonvolatile semiconductor memory device that has high-performance writing/deletion characteristic.

SOLUTION: A selection gate 18 is formed on a p-type well 2 of a semiconductor substrate with a gate insulation film 6 in between, and a memory gate 17 is formed on the p-type well 2 with a lamination film 15 formed of a silicon oxide film 15a, a silicon nitride film 15b and a silicon oxide film 15c in between. The memory gate 17 is adjacent to the selection gate 18 with the lamination film 15 in between. N-type impurity diffused layers 20 and 21 are formed as a source and a drain in areas on both sides of the selection gate 18 of the p-type well 2 and the memory gate 17. The charge density of impurities in an area 51 to be controlled by the selection gate 18 is different from that in an area 52 to be controlled by the memory gate 17.

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