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The electrical characteristics of a-IGZO thin-film transistors (TFTs) with HfO2 and HfON/HfO2/HfON (NON) tri-stack gate dielectrics are comparative investigated. Experimental results indicate that NON gate dielectric can effectively improve interface properties and enhance device reliability compared to HfO2 gate insulator. Bottom gate a-IGZO TFTs with NON gate dielectrics exhibit improved performance with a saturation mobility of 10.2 cm2/V·s, an on-off current ratio of 2.2 × 106, a subthreshold slope of 0.13 V/decade, and a threshold voltage shift of 0.7 V after gate bias stress at 10 V for 300 s, which are ascribed to the inserting of HfON interlayers between substrate and HfO2, and between HfO2 and channel film.
Date of Conference: 1-4 Nov. 2010