MIS semiconductor device having improved gate insulating film reliability

摘要

A reliability evaluation value of a gate insulating film of an insulated gate type (MIS) transistor in an unselected state is set to a value equal to or smaller than the reliability evaluation value of the gate insulating film of the MIS transistor in a selected state. An electric field applied to the gate insulating film is determined in accordance with the reliability evaluation value. Therefore, it is possible to the gate insulating film applied electric field of the MIS transistor in the unselected state lower than the electric field in the selected state to assure the reliability of the gate insulating film of the MIS transistor in the unselected state. Thus, the reliability of the gate insulating film of the MIS transistor in the unselected state is assured, and a semiconductor device with an improved gate dielectric characteristics.