Nonvolatile semiconductor memory device

摘要

A nonvolatile semiconductor memory device has reduced parasitic capacitance at a select transistor obtained by providing a depletion-mode select transistor with a charge accumulation layer, virtually making a gate insulating film thicker, or providing under the gate insulating film a channel layer that is of a same conductivity type as that of a source and drain regions and connects thereto, thereby enabling the potential of the select gate to be almost fixed at a desired value, preventing a faulty operation and making it possible to cause the select transistor to operate at high speed.