In situ formation of inhibitor species through catalytic surface reactions during area-selective atomic layer deposition of TaN

Abstract

Small molecule inhibitors (SMIs) have been gaining attention in the field of area-selective atomic layer deposition (ALD) because they can be applied in the vapor-phase. A major challenge for SMIs is that vapor-phase application leads to a disordered inhibitor layer with lower coverage as compared to self-assembled monolayers, SAMs. A lower coverage of SMIs makes achieving high selectivity for area-selective ALD more challenging. To overcome this challenge, mechanistic understanding is required for the formation of SMI layers and the resulting precursor blocking. In this study, reflection adsorption infrared spectroscopy measurements are used to investigate the performance of aniline as an SMI. Our results show that aniline undergoes catalytic surface reactions, such as hydrogenolysis, on a Ru non-growth area at substrate temperatures above 250 °C. At these temperatures, a greatly improved selectivity is observed for area-selective TaN ALD using aniline as an inhibitor. The results suggest that catalytic surface reactions of the SMI play an important role in improving precursor blocking, likely through the formation of a more carbon-rich inhibitor layer. More prominently, catalytic surface reactions can provide a new strategy for forming inhibitor layers that are otherwise very challenging or impossible to form directly through vapor-phase application.