| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce a circuit size of a semiconductor device or improve capability of driving the semiconductor device. <P>SOLUTION: A transistor whose channel region includes an oxide semiconductor is used as a pull down transistor. The oxide semiconductor has a band gap of ≥2.0 eV, preferably ≥2.5 eV, and more preferably ≥3.0 eV. Thus, hot carrier degradation in the transistor can be suppressed. Consequently, the circuit size of the semiconductor device including the pull down transistor can be reduced. Further, a gate of a pull up transistor is made to be in a floating state by switching the pull down transistor. The off-state current of the transistor can be controlled to ≤1 aA/μm (1×10<SP>-18</SP>A/μm) by highly purifying the oxide semiconductor. Thereby, the driving capability of the semiconductor device can be improved. <P>COPYRIGHT: (C)2011,JPO&INPIT |
