Logic circuits

Abstract

To provide a logic circuit that prevents malfunctions or reduces power consumption. [Solution] The logic circuit includes thin-film transistors 11-14 whose channel formation region is made of oxide semiconductor, and a capacitive element 15 whose potential at one terminal becomes detached when thin-film transistors 13 and 14 are turned off. The oxide semiconductor has a hydrogen concentration of 5 × 10 19 (atoms / cm 3 The off-current of the thin-film transistor is less than or equal to the minimum current, and in the absence of an electric field, it functions as an insulator. Therefore, the off-current of the thin-film transistor can be reduced. This suppresses the leakage of charge accumulated in the capacitive element through the thin-film transistor. As a result, malfunctions of the logic circuit can be prevented. In addition, by reducing the off-current of the thin-film transistor, the wasted current flowing through the logic circuit can be reduced. This reduces the power consumption of the logic circuit.

Claims

[Claim 1] The thin-film transistor has a state where, when turned off, the potential of the node to which one of the first and second terminals is electrically connected becomes floating. The channel formation region of the thin-film transistor has a hydrogen concentration of 5 × 10 １９ (atoms / cm ３ A logic circuit characterized by being composed of the following oxide semiconductors.

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