Highly selective atomic layer deposition of MoSiOx using inherently substrate-dependent processes

Abstract

A resistive MoSiOx film was deposited with high selectivity on Si in preference to SiO2 and SiN using MoF6, Si2H6 and O2 as reactants. Two different approaches were demonstrated via thermal atomic layer deposition (ALD). First, ALD of MoSiOx by sequential dosing of MoF6, Si2H6 and O2 (ABC-type) at 200 °C followed by an ex-situ post-deposition anneal (PDA) in O2 at 350 °C was performed. The growth of the film using the ABC-type deposition was limited to ~5.25 ± 0.5 nm because the insulating film inhibits the MoF6 and Si2H6 ALD reaction. The second method was to grow MoSix at 120 °C and employ a post-deposition anneal in O2/He at 350 °C (AB + C-type) to form MoSiOx. The selectivity of this process on Si versus SiO2 was perfect for 10 nm of deposition on Si, as there were no nuclei or particle formation observed on the SiO2 surface by atomic force microscopy (AFM). The high selectivity can be obtained due to the inherent inability of MoF6 to react SiO2 and SiN surfaces. Transmission electron microscopy (TEM) of a nanoscale-patterned sample demonstrated that the highly selective MoSiOx can be achieved and be integrated into three-dimensional nanoscale structures.