P‐11: DC/AC Electrical Instability of R.F. Sputter Amorphous In‐Ga‐Zn‐O TFTs

Abstract

The paper presents the study of electrical instability of RF sputter amorphous In‐Ga‐Zn‐O (a‐IGZO) thin‐film transistor (TFT) induced by negative steady‐state (or D.C.) bias‐temperature‐stress (BTS). Similarly to positive BTS results [8], the stress time evolution of the threshold voltage shift (Δ V th ) induced by negative BTS under different stress voltages and temperatures can all be described by the stretched‐exponential model. for the first time, we also present the results for Δ V th under pulse (or A.C.) BTS. The Δ V th for positive A.C. BTS is found to have a pulse‐period dependence while a huge reduction of Δ V th is found for all negative A. C. BTS results. This might suggest the time for holes to accumulate near the a‐IGZO/ SiO 2 interface is much longer than the time for electrons. The effect of bi‐polar stressing is also discussed.