Insights into metal drift induced failure in MOL and BEOL

Metal drift induced dielectric failure is a critical concern in deeply scaled MOL and BEOL systems. To better understand the underlying physics, we investigated metal drift induced dielectric degradation using planar capacitors. Based on triangular voltage sweep results, failure is attributed to local metal filament formation and growth. Combined with an area scaling study, the time dependent dielectric breakdown measurements performed at different temperatures show that metal filament growth limits the failure times at high fields, while metal filament formation is more dominant at low fields. The influence of these two mechanisms on top of intrinsic dielectric degradation makes the collection of reliability data in a wide field and temperature test window inevitable for reliable lifetime predictions.