Improved subthreshold swing and gate bias stressing stability of a-IGZO thin-film transistors with HfON/HfO2/HfON tri-stack dielectrics

The electrical characteristics of a-IGZO thin-film transistors (TFTs) with HfO
₂
and HfON/HfO
₂
/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 HfO
₂
gate insulator. Bottom gate a-IGZO TFTs with NON gate dielectrics exhibit improved performance with a saturation mobility of 10.2 cm
²
/V·s, an on-off current ratio of 2.2 × 10
⁶
, 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 HfO
₂
, and between HfO
₂
and channel film.