LOW-TEMPERATURE-PROCESSED POLY-SI THIN-FILM TRANSISTORS USING SOLID-PHASE-CRYSTALLIZED AND LIQUID-PHASE-DEPOSITED GATE OXIDE

Abstract

Poly-Si thin-film transistor (TFT) devices using solid-phase-crystallized and liquid-phase-deposited gate oxide are, for the first time, realized by low-temperature processes (LTP) (<625-degrees-C) for future LCDs and 3-D integrated circuits. The method of liquid-phase deposition of SiO2 (LPD-SiO2) is described. The physical, chemical and electrical properties of the new dielectric layer are clarified. The TFT (W/L = 200 mum/10 mum) having an on-off current ratio of 10(6) at V(D) = 5 V, a field-effect mobility of 15 cm2/V.s at V(D) = 0.1 V, a threshold voltage of 5.6 V, and a subthreshold swing of 1.6 V/decade, exhibits sufficient performance for pixel transistors. The field-effect mobility is strongly dependent on channel length. Effective passivation of defects by plasma hydrogenation will be very essential to achieve higher performance.