Impact of Mechanical Stress on IGZO TFTs: Enhancing PBTI Degradation

TL;DR

This paper explores how out-of-plane compressive mechanical stress affects IGZO TFTs, revealing that it causes positive threshold voltage shifts and worsens PBTI degradation, which is vital for future 3D DRAM device reliability.

Contribution

It demonstrates the influence of mechanical stress on IGZO TFT performance and reliability, highlighting the importance of stress management in 3D device fabrication.

Findings

MS induces positive Vth shift in IGZO TFTs

MS enhances electron trapping during PBTI tests

Residual MS impacts device reliability and performance

Abstract

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 Vth 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 AlOX 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.