Ruthenium Metallization and Via Prefill for Electromigration Reliability Enhancement in Advanced Sub-3 nm Node Interconnects

Addressing electromigration (EM) reliability at system-level poses significant challenges, particularly in the context of advanced nodes. Utilizing physics-based models for such circuits becomes impractical due to excessive computational cost. Conversely, the conventional designer approach to EM-compliance checks tends to be overly simplistic, as it neglects the statistical impact of interconnect population on the chip-failure probability. In this study, a statistical approach, known as Statistical Electromigration Budgeting (SEB), is employed to evaluate the EM reliability of a Power Delivery Network (PDN) in a commercial design. As part of the study, various advanced metallization options are applied to lowest metal layers (Mx) to highlight the need for SEB approaches for EM-compliance screening. Implementation of ruthenium (Ru) via prefill results in a significant 2.5× improvement in system EM lifetime with respect to dual damascene copper (DD-Cu) metallization, thus highlighting the impact of via EM. In contrast, ruthenium metallization, known for being extremely resilient to EM, exhibits an impressive 10× increase in system EM lifetime. Moreover, considering the short-length effect (SLE) improves lifetime of DD-Cu and via prefill options by 2.5× and 1.5×, respectively.