Achieving area-selective atomic layer deposition with fluorinated self-assembled monolayers

Abstract

In recent years, semiconductor devices have been scaled down to beyond 5 nm nodes through higher transistor densities and aspect ratios. Therefore, area-selective atomic layer deposition (AS-ALD) has drawn great attention in nanopatterning processes and provided an alternative bottom-up approach. Although AS-ALD has been demonstrated using different strategies, it remains a great challenge to achieve higher selectivity in the deposition between growth and non-growth regions. To improve the deposition selectivity, in this study, we performed AS-ALD of Al₂O₃ using alkylphosphonic acid self-assembled monolayers with different substituent groups, alkyl chains (C10PA) and fluoroalkyl chains (FC10PA). The SAM-modified Co substrates exhibit selective behaviors against ALD deposition compared with the untreated Co substrates; the FC10PA SAM-modified Co substrates exhibit better blocking ability towards the Al₂O₃ deposition than the C10PA-modified SAM due to the low surface free energy (10.5 mN m⁻¹) and amphiphobic property of the fluorinated chains, as determined by XPS. Furthermore, AS-ALD through FC10PA SAM treatments is demonstrated on Co/SiO₂ patterned wafers and characterized by TEM and EDS mapping analysis. This study not only offers an accessible method to fabricate fluorinated modified SAMs but also deepens the understanding of surface properties on AS-ALD.