Session: Surface Chemistry:

As the demand for faster processing systems continues to grow, questions in regard to the limitations of current IC technology are being raised. In an attempt to continue the evolution of Moore’s Law, wideband gap (WBG) semiconductors are being introduced due to their greater power density and increased energy efficiency. As a result of increased chemical inertness and strength of these WBG materials, traditional CMP processes of obtaining material removal rate (MRR) at reduced substrate defectivity has proven to be difficult. More specifically current WBG processes utilize aggressive redox chemistry coupled with harsh abrasive conditions to achieve optimal throughput. As a result of these conditions, surface defectivity has emerged as a major challenge. This work focuses on understanding the synergy at the slurry additive-substrate interface in order to enhance the removal mechanism. Results have shown that the removal mechanism is highly dependent on the interaction of the substrate with additives producing an electrophilic chemistry-nanoparticle macroenvironment, which enhances the formation of an effective surface complexation layer. This modified layer contributes to the weakening of the surface structure (i.e. Si-C or Al-O bonds) leading to more efficient low-stress mechanical abrasion. The addition of organo-metallic complexes works as a vehicle to modulate the electrophilicity of the macroenvironment thereby increasing the affinity for the surface which is evident by changes in surface contact angle. When in the presence of hydrogen peroxide (H₂O₂), these organo-metallic complexes can synergistically interact to aid in the production of hydroxyl radicals (*OH) to increase the oxidation of the surface. This enhanced surface complexation mechanism has shown to directly correlate to significant increases MRR on both the SiC and sapphire substrates albeit at reduced interfacial shear force.

Jason Keleher

Lewis University

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