SEMICONDUCTOR DEVICE MANUFACTURING METHOD

摘要

PROBLEM TO BE SOLVED: To prevent malfunction of a logic circuit; or reduce power consumption.SOLUTION: A logic circuit has: thin film transistors 11-14, 21-24 in each of which a channel formation region is composed of an oxide semiconductor; and capacitative elements 15, 25 each of which has a terminal where potential becomes a floating state when the thin film transistors 14, 24 are turned off. The oxide semiconductor has a hydrogen concentration of 5×10(atoms/cm) and under and functions substantially as an insulator in a state where an electric field is not generated thereby to reduce off-state current of the thin film transistor. This inhibits leakage of charge accumulated in the capacitative element via the thin film transistor to prevent malfunction of the logic circuit. Further, wasted current which passes through the logic circuit is reduced.