| 摘要 |
<p>PROBLEM TO BE SOLVED: To enable effectively performing erasing operation of a memory cell, by maintaining a breakdown voltage between pocket wells and a substrate to be high. SOLUTION: This semiconductor storage device is provided with a large number of first impurity regions and a second impurity regions, which are formed on a semiconductor substrate 100 of a first conductivity type, and provided as the wells of a second conductivity type opposite to the first conductivity type; a large number of third impurity regions which are formed on the substrate except a large number of the first impurity regions and the second impurity regions of the second conductivity type, and provided as the wells of the first conductivity type; and fourth impurity regions which are formed in a large number of the first impurity regions of the second conductivity type, and provided as the wells of the first conductivity type. Impurity concentration of the first impurity regions of the second conductivity type is gradually decreased by increase of a depth of the substrate, and impurity concentration of the fourth impurity regions of the first conductivity type has at least two peaks by increase of a depth of the substrate.</p> |
