Material analysis of Cu end-point detection for advanced node PFIB delayering process optimization

As integrated circuits continue to scale down to ever-smaller dimensions and increased complexity, traditional failure isolation & analysis (FA/FI), and sample preparation techniques face significant limitations. The increasing density of modern semiconductor devices, now advancing beyond 3 nm technology nodes, presents unprecedented challenges in precise layer-by-layer analysis. Over the past decade, Xenon (Xe) Plasma Focused Ion Beam (PFIB) gas assisted delayering has emerged as a standard industry technique for precise layer-by-layer delayering of integrated circuits.
Recent studies have validated PFIB delayering as an effective sample preparation technique for nanoprobing applications. Research on 14 nm FinFET devices in SRAM arrays has demonstrated the technique's capability to provide clean, artifact-free surfaces suitable for atomic force nanoprobing (1). Furthermore, advancements in PFIB delayering have enabled successful nanoprobing of 5 nm node devices (2), confirming its applicability to cutting-edge semiconductor technologies.
While previous studies have focused on electrical and topographical characterization of PFIB delayering (3,4), comprehensive material and chemical analysis of the delayering process remains crucial, particularly for Cu interconnect end-point monitoring. This study addresses the chemical and structural characterization of PFIB-delayered surfaces, with specific emphasis on the material properties of Cu lines end-point detection.
This comprehensive characterization aims to optimize failure analysis protocols and establish parameters for automated end-point detection.