Dielectric breakdown analysis on bottom and top-gated IGZO-TFT

Abstract

Reliability in IGZO thin-film transistors (TFT) is known to be limited by Bias Temperature Instability (BTI), however there are no detailed studies on other reliability mechanisms, like dielectric breakdown. We study both bottom-gated and top-gated transistors and find different area scaling trends in those devices, which could be partially explained with a non-uniform voltage distribution across the active area during the voltage accelerated breakdown stress. Both bottom and top-gated TFT obtain a maximum tolerable voltage of more than 2 V at 95°C for 10 years. Even for the smallest measured device, 80x25 nm2, breakdown is not a reliability concern.