"Role of Interfaces in the Electromigration Lifetime of Cu Interconnects for Advanced Packaging" 

Faharia Hasan Bhuiyan, MSE PhD Candidate 

Advisor: Professor Shubhra Bansal

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ABSTRACT

As the semiconductor industry transitions into the post-Moore's Law era, heterogeneous integration has emerged as a key strategy to meet the growing demand for higher performance and functionality. Fine-pitch copper (Cu) interconnects play an important role in achieving the performance goals by increasing the number of electrical connections between stacked dies and other components. However, this trend brings with it significant reliability challenges, such as electromigration and thermomigration, which become more pronounced in interconnects with smaller linewidth and high-power density. Electromigration, driven by atomic diffusion under high current densities, is a critical factor limiting the operational lifetime of Cu interconnects in advanced packaging applications. This report explores the strategies to improve the electromigration resistance of Cu interconnects, focusing on the role of diffusion barrier and passivation layers. A comprehensive review is presented on both traditional and emerging materials for barrier and passivation layers, with particular attention to their impact on the interfacial diffusion process, which is the primary driver of electromigration in Cu. Through a detailed review of materials used for diffusion and passivation layers, this report highlights the critical role of interfaces in improving the electromigration lifetime of Cu interconnects and explores emerging materials for the next generation of semiconductor devices.