Sub- µm polysilicon super thin film transistor

The application of poly Si super thin film transistors to VLSI technology, in which the active layer poly Si is 200-500Å thick, has been investigated. The average grain sizeo of poly Si increased to more than 1µm from 200-300 Å by solid phase recrystallization. Sub-µm poly Si super thin film transistors and 19-stage CMOS ring oscillators were fabricated on 5inch insulator substrates. The mobility was about 100cm²/V.s for an N-channel and about 80cm²/V.s for a P-channel transistor. The leakage current of transistors was 0.1pA/µm. The threshold voltage was 0.8V for an N-channel and -0.8V for a P-channel transistor, respectively. 150ps of the delay time per stage and 0.15pJ/gate of power-delay product at VDD=5V were obtained in the ring oscillator.