Role of in-situ hydrogen plasma treatment on gate bias stability and performance of a-IGZO thin-film transistors
Om Kumar Prasad, Srikant Kumar Mohanty, Chien‐Hung Wu, Tsung Ying Yu, Kow Ming Chang
Abstract
Abstract This work investigates the effect of an in situ hydrogen plasma treatment on gate bias stability and performance of amorphous InGaZnO thin-film transistors (TFTs) deposited by using atmospheric-pressure PECVD. The H 2 plasma-treated a -IGZO channel has shown significant improvement in bias stress induced instability with a minuscule threshold voltage shift (Δ V th ) of 0.31 and −0.17 V under positive gate bias stress (PBS) and negative gate bias stress (NBS), respectively. With the aid of the energy band diagram, the proposed work demonstrates the formation of negative species O 2 − and positive species H 2 O + in the backchannel under PBS and NBS in addition to ionized oxygen vacancy (V o ) defects at a -IGZO/ZrO 2 interfaces are the reason for gate bias instability which could be effectively suppressed with in situ H 2 plasma treatment. From the experimental result, it is observed that the electrical performance such as field-effect mobility ( μ FE ), on-off current ratio ( I on / I off ), and subthreshold swing improved significantly by in situ H 2 plasma treatment with passivation of interface trap density and bulk trap defects.