As-Received, Ozone Cleaned and Ar+ Sputtered Surfaces of Hafnium Oxide Grown by Atomic Layer Deposition and Studied by XPS

XPS survey and multiplex spectra were collected from 47 nm thick HfO2 films grown by atomic layer deposition (ALD). Measurements were made for as-received, ozone cleaned and surfaces cleaned by sputtering with 2kV Ar+ for 180 sec. The data were collected on a Physical Electronics Quantum 2000 Scanning ESCA Micoprobe using monochromatic Al K alpha x-ray (1486.7 eV) excitation. The ALD films were grown using tetraethylmethylaminohafnium (TEMAH) as a precursor. Survey spectra showed the presence of C, O and Hf. Surface hydrocarbon contamination made up approximately 19 atom percent (at%) or approximately 0.5 monolayers (ML) of the as received surface concentration. After treatment by UV in air, the surface hydrocarbon concentration was reduced to approximately 2.5 at% or 0.06 ML. The 1 at% of carbon that remained after sputtering had a binding energy characteristic of carbide believed to be formed by the ion sputtering process. The formation of the low binding energy Hf 4f lines indicates reduction of the Hf oxide due to preferential sputtering. (C) 2011 American Vacuum Society.