Sustained Area-Selectivity in Atomic Layer Deposition of Ir Films: Utilization of Dual Effects of O 3 in Deposition and Etching.

Area-selective deposition (ASD) based on self-aligned technology has emerged as a promising solution for resolving misalignment issues during ultrafine patterning processes. Despite its potential, the problems of area-selectivity losing beyond a certain thickness remain critical in ASD applications. This study reports a novel approach to sustain the area-selectivity of Ir films as the thickness increases. Ir films are deposited on Al ₂ O ₃ as the growth area and SiO ₂ as the non-growth area using atomic-layer-deposition with tricarbonyl-(1,2,3-η)-1,2,3-tri(tert-butyl)-cyclopropenyl-iridium and O ₃ . O ₃ exhibits a dual effect, facilitating both deposition and etching. In the steady-state growth regime, O ₃ solely contributes to deposition, whereas in the initial growth stages, longer exposure to O ₃ etches the initially formed isolated Ir nuclei through the formation of volatile IrO ₃ . Importantly, longer O ₃ exposure is required for the initial etching on the growth area(Al ₂ O ₃ ) compared to the non-growth area(SiO ₂ ). By controlling the O ₃ injection time, the area selectivity is sustained even above a thickness of 25 nm by suppressing nucleation on the non-growth area. These findings shed light on the fundamental mechanisms of ASD using O ₃ and offer a promising avenue for advancing thin-film technologies. Furthermore, this approach holds promise for extending ASD to other metals susceptible to forming volatile species.
(© 2024 The Author(s). Small published by Wiley‐VCH GmbH.)