Cobalt Precursor as Surface Inhibitor for Area-Selective Atomic Layer Deposition of Nanoscale Electronic Interconnects

In light of recent progress in semiconductor technology, ongoing efforts are directed toward achieving further reductions in the feature sizes of nanoscale semiconductor interconnects in semiconductor devices. The pursuit of improving area selective deposition (ASD) methods has led researchers to explore surface modifications, using surface inhibitors as a tool to optimize ASD techniques for precise nanopatterning. Utilizing precursor inhibitor (PI) in ASD is a promising substitute for self-assembled monolayer (SAMs), owing to its broad material selection and superior process compatibility for fabricating nanostructured semiconductor devices. In this study, CoCp2 PI was utilized, and a preliminary surface treatment approach, involving exposure to ammonia plasma before the exposure of CoCp2, was carried out to increase the inhibitor’s adsorption, potentially improving the blocking efficiency of atomic layer deposition (ALD) of nanometer-thick dielectric and metallic films. Substrates of inhibited copper with ammonia plasma pretreatment exhibited superior selectivity, approximating 100% after 10 cycles of HfO2 ALD and 100 cycles of Ru ALD, compared to inhibited substrates without pretreatment. The pretreatment creates surface sites that are more reactive toward CoCp2 than the naturally occurring hydroxyl-terminated surface, leading to a more uniform and effective blocking layer that impedes ALD nucleation on the Cu surface more effectively than on the SiO2 surface. These results align cohesively with theoretical studies, suggesting that the study of PI, coupled with enhanced selectivity through NH3 plasma pretreatment, could pave the way for groundbreaking research in nanoscale semiconductor manufacturing.