BTI Reliability of IGZTO FETs: Hydrogen Dynamics, AC/DC Stress Effects, and Advanced Modeling

This article presents an in-depth investigation into the role of hydrogen (H) in the reliability of indium–gallium–zinc–tin-oxide (IGZTO) field-effect transistors (FETs) under both direct current (dc) and alternating current (ac) stress conditions. By systematically examining the effects of H on negative bias temperature instability (NBTI) and positive bias temperature instability (PBTI), we provide critical insights into H-induced degradation mechanisms and their response to ac signals. Our findings reveal: 1) dc NBTI exhibits a saturation behavior with lower degradation severity compared to PBTI; 2) H<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> ions in NBTI demonstrate a weak response to ac stress, leading to ultrastable ac reliability performance; and 3) electrochemical impedance spectroscopy (EIS) confirms the presence and migration dynamics of H<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> ions in IGZTO FETs. A comprehensive model based on the collective behavior of H<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> migration is proposed, accurately capturing the threshold voltage shift (Δ<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>th</roman></sub><roman xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">)</roman> under ac and dc BTI conditions. This study provides essential insights for enhancing the long-term reliability of oxide–semiconductor (OS) devices in advanced electronics.