| 摘要 |
PROBLEM TO BE SOLVED: To provide the semiconductor storage device which has small gate variance among select gates and small cell size and can operate fast, and its manufacture. SOLUTION: The semiconductor storage device has side walls 13 formed as both side walls of a stack gate 12 by performing a floating gate forming process, a control gate forming process, a drain line forming process, a side wall forming process, a source forming process, and a select gate forming process in order, and a side wall 13 on the side of a source 14 is used as a select gate 7. Impurities are injected into a source 14 across the select gate 7 to reduce the variance of the select gate 7. In the side wall forming process, accelerated oxidation is caused on a drain 9 by the oxidation of the select gate 7 to make its film thickness larger than the oxide film thickness of the select gate 7 and in the floating gate forming process, element separation is carried out by boron injection. Impurity injection in the source forming process is performed independently of the drain line forming process to make the impurity density of the drain 9 different from that of the source 14. |
