Nonvolatile semiconductor memory device and its manufacturing method.

摘要

A select MOS transistor (ST) and a data storage MOS transistor (MT) are formed in an element region. The transistor (MT) has floating-gate electrodes (71A, 71B). The floating-gate electrodes (71A, 71B) are spaced apart above the element region and connected to each other above a field region. Only a tunnel insulating film (66) much thinner than a gate insulating film (68) of the transistor (ST) is placed between the floating-gate electrode (71A) and a drain region (63). Only the gate insulating film (66) much thinner than the gate insulating film of the transistor (ST) is placed between the floating-gate electrode (71B) and the channel region of the transistor (MT). In the element region, the shape of a control electrode (75) is the same as that of the floating-gate electrodes (71A, 71B).