Suppression of Hydrogen Incorporation by Substrate Bias in NH ₃ ‐Free ICP‐CVD SiN _x Thin Film Deposition

ABSTRACT

SiN _x films were deposited by NH ₃ ‐free ICP‐CVD to reduce hydrogen incorporation, while applying 2 MHz substrate bias to enhance nitrogen‐ion participation. Increasing bias power increased the N/Si ratio and decreased hydrogen content, reaching 8% at 120 W. When used as the gate dielectric in IGZO TFTs, the low‐H SiN _x significantly improved transfer characteristics, achieving a subthreshold swing of 240 mV/dec and an on/off ratio of 1.9 × 10 ⁹ . The optimized SiN _x also exhibited a high dielectric breakdown strength of 8 MV/cm. These results demonstrate an effective bias‐assisted, NH ₃ ‐free route to suppress hydrogen incorporation in SiN _x and enhance dielectric and device performance.