From atomic attrition to mild wear at multi-asperity interfaces The wear of hard Si₃N₄ repeatedly contacted against soft Si

Wear causes surfaces to be irreversibly damaged, thereby incurring significant economic cost, for instance in the semiconductor industry. Much progress has been made in describing wear at single asperity interfaces between silicon based materials (Si, SiO_x, Si₃N₄), translating the fundamental understanding of wear into wear predictions and control over wear. Yet, predicting and controlling wear at industrially relevant multi-asperity interfaces remains a challenge, especially when considering the wear of the harder material subjected to repeated, nanometric scale displacement. We studied pre-sliding Si₃N₄-on-Si wear using the atomic force microscopy topography difference method and showed that the harder Si₃N₄ wears through either atomic attrition or ductile removal enhanced by subsurface damage, depending on the magnitude of the local Si₃N₄-on-Si contact pressure. Our methods and results bridge fundamental insight into wear based on nanoscale studies to industrial applications.