Revealing Asymmetric Off-State Drain/Source Stress Reliability and Mechanisms in IGZO-FETs

Area of Science:

• Materials Science
• Semiconductor Physics
• Device Engineering

Background:

• Amorphous indium-gallium-zinc oxide field-effect transistors (IGZO-FETs) are crucial for 3D integration but suffer from reliability issues.
• Defects in the amorphous IGZO channel and gate oxide (GOX) contribute to device instability.

Purpose of the Study:

• To investigate the reliability of IGZO-FETs under off-state drain/source stress (ODS/OSS).
• To understand the asymmetric threshold voltage (Vth) and subthreshold swing (SS) shifts observed during stress.

Main Methods:

• Experimental investigation of IGZO-FETs under ODS/OSS conditions.
• Development of a physics-based model to capture current-voltage (I-V) dynamics.
• Analysis of electron detrapping and density of states (DoS) reconfiguration.

Main Results:

• Observed distinct asymmetric shifts in Vth and SS, challenging symmetry assumptions.
• Identified electron detrapping at the IGZO/GOX interface and DoS reconfiguration in IGZO as key mechanisms.
• Accurately modeled I-V dynamics using a physics-based approach.

Conclusions:

• The interplay between electron detrapping and DoS reorganization drives asymmetric degradation in IGZO-FETs under off-state stress.
• Findings advance the understanding of amorphous oxide semiconductor reliability for 3D integration.
• Highlights the critical impact of off-state stress on IGZO-FET performance.