| 摘要 |
PROBLEM TO BE SOLVED: To actualize a floating gate memory which is free of writing errors causing readout destruction, even if a tunnel insulating film is made thin as to a semiconductor storage device. SOLUTION: This device has a doped 1st channel part 13A, which operates at write and erase time between a source region 24S and a drain region 24D, a 1st tunnel insulating film 14A which covers the 1st channel part 13A and has thickness allowing a carrier directly tunnel, a 2nd channel part 13B which operates at reading time between the source region 24S and drain region 24D and is doped to decrease density lower than the 1st channel part 13A, a 2nd tunnel insulating film 14B which covers the 2nd channel part 13B and allows a carrier to directly tunnel and is thicker than the 1st tunnel insulating film, a floating gate 15 which is present on each tunnel insulating film, and a control gate 17 which is formed on the floating gate 15 across a control gate insulating film 16.
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