Impact of the Low Temperature Gate Dielectrics on Device Performance and Bias-Stress Stabilities of a-IGZO Thin-Film Transistors

In this work, amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor's (TFT) characteristics with five different gate dielectrics (PECVD SiO 2 , PECVD SiN x , ALD Al 2 O 3, PVD SiO 2 and PVD Al 2 O 3 ) deposited at temperature lower than 250°C have been studied. Their characteristics are compared to the TFTs with thermally grown SiO 2 as gate dielectric. Among them, ALD Al 2 O 3 gate dielectric based a-IGZO TFTs showed comparable characteristics to the thermally grown SiO 2 dielectric based TFTs. PECVD SiO 2 , PECVD SiN x , PVD SiO 2 and PVD Al 2 O 3 dielectric based TFTs showed inferior characteristics. We attributed this to good electrical, morphological and chemical properties of ALD Al 2 O 3 dielectric layer compare to PECVD SiO 2, PECVD SiN x , PVD SiO 2 and PVD Al 2 O 3 dielectric layers.