Plasma-Enhanced Molecular Layer Deposition of Phosphane-Ene Polymer Films

A vapor-phase molecular layer deposition (MLD) process generating phosphorus-rich phosphane-ene polymer networks was adapted from known solution-phase methods and successfully used in a commercial atomic layer deposition tool. By using plasma-enhanced MLD on Si/SiO2 and Al2O3 substrates, film deposition was carried out with a commercially available primary phosphine, iBuPH2, paired with a known volatile cyclic siloxane precursor, tetramethyltetravinylcyclotetrasiloxane (D4Vinyl). The deposition process used radicals generated by an Ar plasma source to facilitate P-H addition to vinyl functionalities on D4Vinyl which yielded a growth per cycle of 0.6-2.0 angstrom, generating 10-120 nm films as determined by atomic force microscopy and scanning electron microscopy measurements. Characterization of the films were carried out using X-ray photoelectron spectroscopy, and oxygen scavenging capabilities were studied using a quartz crystal microbalance, showing an uptake of oxygen by a 12 nm depth of a freshly deposited polymer film.