Synergistic Effect of Pad “Macroporous-Reactors” on Passivation Mechanisms to Modulate Cu Chemical Mechanical Planarization (CMP) Performance

Abstract

Decoupling the key interfacial mechanisms (chemical and mechanical) present during Cu CMP is critical to the development of slurry/pad consumable sets to reduce defectivity at advanced technology nodes. Understanding the Prestonian relationship, or lack thereof, can give rise to correlations between film density as a result of passivation film kinetics and thermodynamics as they relate to Cu oxidation/electrochemistry under dynamic conditions. The efficiency of film removability is strongly correlated to the molecular structure of the passivating agent and its synergistic relationship with the macroporous-reactor sites presented in this work. Results indicate that passivation film activation energy (Ea) is altered by the transport of fresh and waste slurry chemistry to the Cu interface via pad asperity contact. Furthermore, this work employs inhibitors with varying structural attributes to probe how the density of film formation is impacted by the efficiency of complexation and non-covalent interactions at the Cu surface. When comparing the best-in-class benzotriazole (BTA) with salicylhydroxamic acid (SHA), the triazole film formation is driven by a traditional complexation/π-stacking mechanism, while the hydroxamic acid film is the result of a colloidal supramolecular complex and soft surface-adsorption requiring reduced downforce for Cu removal.