GROWTH AND CHARACTERIZATION OF YTTRIUM-OXIDE THIN-LAYERS ON SILICON DEPOSITED BY YTTRIUM EVAPORATION IN ATOMIC OXYGEN

Polycrystalline yttrium oxide films have been grown cinder high vacuum conditions by evaporation of yttrium in an atomic oxygen plasma. Well -oxidized uniform layers in the thickness interval 30-170 nm were depo sited on silicon over a large temperature range (80-800 degrees C). Fi lm surfaces were very smooth with average surface roughness 1.6 nm for 70 nm films grown at 350 degrees C. No impurity phases were found by X-ray diffraction even for the highest growth temperatures. The layers exhibited a strong (111) texture for growth temperatures greater than or equal to 300 degrees C irrespective of the substrate orientation. High frequency capacitance-voltage measurements on aluminium/yttrium o xide/silicon capacitors showed metal-insulator-semiconductor operation with large hysteresis effects in the depletion region. The calculated values of the relative dielectric constant for the capacitor structur es were 14 and 11 for 100 nm thick yttrium oxide films grown at 350 de grees C and 750 degrees C, respectively. The breakdown strength of the capacitors was found to be 3.8 MV cm(-1).