Non-volatile semiconductor memory device and manufacturing method thereof

摘要

Memory cell gates are formed on the main surface of a semiconductor substrate (1) via a gate isolation film (5). Source regions (3) and drain regions (4) are formed on both sides of the memory cell gates (2). The source regions (3) have p<-> impurity regions (3a) and n<+> impurity regions (3b) while the drain regions (4) have p<-> impurity regions (4a) and n<+> impurity regions (4b). And the concentration of the p<-> impurity regions (3a) is made higher than the concentration of the p<-> impurity regions (4a) while the concentration of the n<+> impurity regions (3b) is made higher than the concentration of the n<+> impurity regions (4b).