Stress effect on the leakage current distribution of ferroelectric Al_0.7Sc_0.3N across the wafer

This study presents an investigation into the stress effect on the leakage current in ferroelectric Al0.7Sc0.3N films by experiments and density functional theory (DFT) computations. The experiments are based on 8-in. 100 nm Al0.7Sc0.3N films obtained from pulsed DC co-sputter deposition technology, which exhibit non-uniform compressive in-plane stress across the wafers and similar distributions of leakage current, suggesting close dependence between each other. DFT computations revealed that stress affects leakage current in two ways: the level of traps introduced by nitrogen vacancy and the formation energy of nitrogen vacancy in Al0.7Sc0.3N. By considering both factors, the leakage current of Al0.7Sc0.3N films increases with larger compressive in-plane stress, as observed in the experimental results. Additionally, the DFT calculation results indicated that the leakage current is more sensitive to compressive stress compared to the tensile, and the minimum leakage current can be obtained with neutral in-plane stress. These findings provide a guideline for stress engineering to optimize the AlScN-based ferroelectric devices.