Impact of ALD on chemistry of stearic acid monolayers
Area-selective atomic layer deposition (AS-ALD) is a promising patterning technique that has attracted increasing attention from the semiconductor and chip manufacturing industry. In one of the most common schemes of AS-ALD, specific surface sites are blocked or passivated by formation of self-assembled monolayers (SAMs), thus becoming chemically inert to the ALD precursors and resulting in deposition only on unblocked areas. Significant efforts have been made to develop suitable inhibitor molecules for AS-ALD. The main challenge in optimizing the SAM chemistry for ALD blocking is the lack of knowledge of how the former is affected during the ALD process. Essentially, it is not very well known if or how the SAMs degrade under ALD conditions, and if the change in SAM chemistry is related to loss of ALD selectivity. AFM-IR is uniquely suited for this problem, since it offers monolayer sensitivity with nanoscale spatial resolution, thus allowing for correlating surface chemistry with morphological aberrations, if any.