Cobalt interconnect integration: progress in metal deposition, chemical mechanical polishing, and post-CMP cleaning for advanced technology nodes

Abstract

Cobalt (Co) emerges as a critical interconnect material for advanced integrated circuits, yet its integration introduces significant fabrication challenges in deposition, chemical mechanical polishing (CMP), and post-CMP cleaning (PCMPC) processes, which are essential for the realization of void-free filling, nanoscale planarity, and residue-free surfaces. We comprehensively evaluate and analyze different deposition methodologies with their unique advantages and the film characteristics (surface roughness, resistivity, etc.) of existing studied processes. For CMP, we decipher the mechanism of slurry components on Co CMP and critically assess Co interconnect CMP slurry formulations based on the material removal rate, galvanic corrosion suppression, and removal selectivity. For PCMPC, this study sketches the cleaning methods, with special emphasis on chemical cleaning strategies for particulate and organic inhibitor residues. Based on a comprehensive literature review, this study clarifies the core mechanisms of each stage of Co interconnect fabrication and assesses how interdependent process conditions shape final interconnect performance through an integrated analysis of the overall process. Additionally, this study examines the challenges and research trends faced by Co interconnect technology when competing with other interconnect technologies. It provides a unique perspective on the future development of Co interconnect integration and offers generalizable strategies for other advanced interconnect fabrication.