Physical Insights of Low Thermal Expansion Coefficient Electrode Stress Effect on Hafnia-Based Switching Speed

TL;DR

This study reveals how low thermal expansion coefficient metals induce in-plane tensile stress during annealing, enhancing switching speed in hafnia-based oxides, with implications for device performance and reliability.

Contribution

It demonstrates the impact of low CTE metals on stress-induced switching speed improvements in hafnia-based devices, highlighting the role of interface defect minimization.

Findings

In-plane tensile stress increases domain switching speed.

Significant speed improvement occurs at electric fields above 1 MV/cm.

Interface defects limit performance at low voltages.

Abstract

In this report, we investigate the effect of low coefficient of thermal expansion (CTE) metals on the operating speed of hafnium-based oxide capacitance. We found that the cooling process of low CTE metals during rapid thermal annealing (RTA) generates in-plane tensile stresses in the film, This facilitates an increase in the volume fraction of the o-phase and significantly improves the domain switching speed. However, no significant benefit was observed at electric fields less than 1 MV/cm. This is because at low voltage operation, the defective resistance (dead layer) within the interface prevents electron migration and the increased RC delay. Minimizing interface defects will be an important key to extending endurance and retention.