Nucleation and Layer Closure Behavior of Iridium Films Grown Using Atomic Layer Deposition

Abstract

Understanding the initial growthprocess during atomiclayer deposition(ALD) is essential for various applications employing ultrathin films.This study investigated the initial growth of ALD Ir films using tricarbonyl-(1,2,3-& eta;)-1,2,3-tri(tert-butyl)-cyclopropenyl-iridium and O-2. IsolatedIr nanoparticles were formed on the oxide surfaces during the initialgrowth stage, and their density and size were significantly influencedby the growth temperature and substrate surface, which strongly affectedthe precursor adsorption and surface diffusion of the adatoms. Higher-densityand smaller nanoparticles were formed at high temperatures and onthe Al2O3 surface, forming a continuous Ir filmwith a smaller thickness, resulting in a very smooth surface. Thesefindings suggest that the initial growth behavior of the Ir filmsaffects their surface roughness and continuity and that a comprehensiveunderstanding of this behavior is necessary for the formation of continuousultrathin metal films.