An ultimately scaled multiple-gate CMOS thin-film transistor with a polysilicon (poly-Si) nanowire demonstrates feasibility for vertical integration using multiple active layers for application in the terabit memory era. The short-channel effects are suppressed using a multiple gate to wrap around the nanowire in devices with a size of a few tenths of a nanometer. The switching and output characteristics show high device performance without a crystallization process for the poly-Si nanowire.