BEOL tip-to-tip dielectric reliability characterization using a design-representative test structure

Abstract

This study presents an innovative approach to characterize the reliability of back-end-of-line (BEOL) dielectrics, particularly focusing on the breakdown between metal tips. By using a design-representative test structure, we implement a novel experimental procedure, referred to as "double V-ramp stress", to discriminate between various failure modes, including line-to-line (L2L), via-to-line (V2L) and tip-to-tip (T2T) breakdowns, and distinctly investigate them. The procedure involves a 4-point voltage stress analysis, where leakage currents at different terminals are meticulously monitored to electrically identify the failure modes at play. Our findings highlight the critical importance of T2T spacing control for enhancing T2T dielectric reliability. We provide insights into the behavior of dielectrics under varied stress conditions, which is key to enable further dimensional scaling of VLSI technologies.