Area-selective atomic layer deposition of Ru thin films using phosphonic acid self-assembled monolayers for metal/dielectric selectivity

Abstract

• For potential AS-ALD applications, metal/dielectric selectivity was investigated. • Selective chemisorption of phosphonic acid SAMs was confirmed on TiN and W surfaces. • Blocking capability of SAMs with different ligands was evaluated against Ru ALD. • Ru AS-ALD was successfully demonstrated on metal/dielectric-patterned substrates. We comparatively investigate inhibitory efficacy of four different phosphonic acid (PA) SAMs, octadecylphosphonic acid (ODPA), octylphosphonic acid (OPA), ethylphosphonic acid (EPA), and phenylphosphonic acid (PPA) on TiN and W versus SiO 2 for technologically important metal/dielectric selectivity. Herein, blocking ability of various PA SAM-treated surfaces was evaluated by using Ru atomic layer deposition (ALD) as a representative model process toward metal/dielectric selectivity. Although chemo-selective adsorption features of PA SAMs were obtained on TiN and W relative to SiO 2 , their blocking quality was shown to improve with increasing alkyl chain lengths via strong van der Waals interactions between adjacent SAMs. With the best efficacy of ODPA SAMs, we successfully demonstrated area selective ALD (AS-ALD) of Ru thin films over 15 nm on patterned TiN/SiO 2 surfaces.