Thermal atomic layer deposition of Er₂O₃ films from a volatile, thermally stable enaminolate precursor

Thin films of Er₂O₃ films were grown by atomic layer deposition using the Er precursor tris(1-(dimethylamino)-3,3-dimethylbut-1-en-2-olate)erbium(III) (Er(L¹)₃), with water as the co-reactant. Saturative, self-limited growth was observed at a substrate temperature of 200 °C for pulse lengths of ≥4.0 s for Er(L¹)₃ and ≥0.2 s for water. An ALD window was observed from 175 to 225 °C with a growth rate of about 0.25 Å per cycle. Er₂O₃ films grown at 200 °C on Si(100) and SiO₂ substrates with a thickness of 33 nm had root mean square surface roughnesses of 1.75 and 0.75 nm, respectively. Grazing incidence X-ray diffraction patterns showed that the films were composed of polycrystalline Er₂O₃ at all deposition temperatures on Si(100) and SiO₂ substrates. X-ray photoelectron spectroscopy revealed stoichiometric Er₂O₃, with carbon and nitrogen levels below the detection limits after argon ion sputtering to remove surface impurities. Transmission electron microscopy studies of Er₂O₃ film growth in nanoscale trenches (aspect ratio = 10) demonstrated conformal coverage.