Degradation phenomenon in metal-oxide-semiconductor thin-film transistors and techniques for its reliability evaluation and suppression

Abstract

Thin-film transistors (TFTs) using metal oxide semiconductors are very promising as driving elements of next-generation displays, and their development is rapidly progressing. However, compared to conventional Si TFTs, they exhibit numerous problems with reliability. In this paper, we outline the observations of various degradation phenomena against electrical bias stress under DC and AC voltage, discuss the degradation mechanism, introduce gate insulation film and protective film which contribute to the improvement of reliability, and propose a reliability evaluation technique using an IR microscope.