Atomic layer deposition of bismuth oxide using Bi(OCMe2iPr)3 and H2O

Bismuth oxide thin films were deposited by atomic layer deposition using Bi(OCMe2iPr)3 and H2O at deposition temperatures between 90 and 270 °C on Si3N4, TaN, and TiN substrates. Films were analyzed using spectroscopic ellipsometry, x-ray diffraction, x-ray reflectivity, high-resolution transmission electron microscopy, and Rutherford backscattering spectrometry. Bi2O3 films deposited at 150 °C have a linear growth per cycle of 0.039 nm/cycle, density of 8.3 g/cm3, band gap of approximately 2.9 eV, low carbon content, and show the β phase structure with a (201) preferred crystal orientation. Deposition temperatures above 210 °C and postdeposition anneals caused uneven volumetric expansion, resulting in a decrease in film density, increased interfacial roughness, and degraded optical properties.