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

Abstract

We comparatively investigate inhibitory efficacy of four different phosphonic acid (PA) SAMs, octadecylphos-phonic acid (ODPA), octylphosphonic acid (OPA), ethylphosphonic acid (EPA), and phenylphosphonic acid (PPA) on TiN and W versus SiO2 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 SiO2, their blocking quality was shown to improve with increasing alkyl chain lengths via strong van der Waals interactions between adjacent SAMs. With the best ef-ficacy of ODPA SAMs, we successfully demonstrated area selective ALD (AS-ALD) of Ru thin films over 15 nm on patterned TiN/SiO2 surfaces.