High performance, low temperature processed Hf-In-Zn-O/HfO2 thin film transistors, using PMMA as etch-stop and passivation layer

Abstract

High performance, low operating voltage and low temperature processed Hf-In-Zn-O/HfO2 thin film transistors (HIZO/HfO2 TFTs), using spin-coated polymethyl-methacrylate (PMMA) as passivation and etch-stop layer (ESL), were fabricated and characterized. Devices showed an average field-effect mobility of 15 cm2/Vs and threshold voltage (VT) of 0.2 V, working in the operating voltage range below 2 V. The Ion/off ratio was 104. Device parameters remained without significant change after months of fabrication. Stability of PMMA passivated devices, after gate and gate-drain bias stress is compared with data reported for other materials used as ESL or passivation layer, showing similar or better performance in preventing threshold voltage shifts, hump, reduction of mobility or of the on/off current ratio.