Impact of Mechanical Stress on IGZO TFTs: Enhancing PBTI Degradation

This study investigates the impact of out-of-plane compressive mechanical stress (MS) on the performance and reliability of n-channel IGZO thin film transistors (TFTs). It is demonstrated that MS induces a positive <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{v}_{\text{th}}$</tex> shift in the device transfer characteristics and enhances electron trapping during Positive Bias Temperature Instability (PBTI) tests. These effects are attributed to the widening of the IGZO bandgap (EG) and increased accessibility of carriers to AlO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> gate oxide trap levels. As substantial residual MS is generated in 3D device processing, understanding its impact on IGZO TFTs is crucial for enabling future 3D DRAM technology.