Patent ID: 8053828

Claim:
A nonvolatile semiconductor memory device comprising: a semiconductor substrate; first and second memory cells formed on the semiconductor substrate; and a first select transistor which is formed on the semiconductor substrate and is adjacent to the first memory cell in a first direction, wherein the first and second memory cells have: first and second channels formed near a surface of the semiconductor substrate; first and second tunnel insulating films formed on the first and second channels; first and second charge storage layers which are formed on the first and second tunnel insulating films and made of an insulating film; first and second block insulating films formed on the first and second charge storage layers; and first and second gate electrodes formed on the first and second block insulating films, respectively, the first select transistor has a third channel formed near the surface of the semiconductor substrate, a first gate insulating film formed on the third channel, and a third gate electrode formed on the first gate insulating film, the first channel includes a first-conductivity-type region and a second-conductivity-type region which is formed on at least a part of the first-conductivity-type region and whose conductivity type is opposite to the first conductivity type, the third channel includes the first-conductivity-type region and the second-conductivity-type region formed on the first-conductivity-type region, and the number of data stored in the first memory cell is smaller than that of data stored in the second memory cell.