Atomic layer deposition of Y2O3 films using heteroleptic liquid (iPrCp)2Y(iPr-amd) precursor

Abstract

Y₂O₃ films grown with a new liquid Y precursor, (iPrCp)₂Y(iPr-amd), have been investigated in terms of the chemical properties of the precursor, atomic layer deposition (ALD) process, and material characterization of the deposited film, as well as its non-volatile resistive switching behavior has been investigated. A heteroleptic (iPrCp)₂Y(iPr-amd) has been synthesized because it exists in a liquid phase at room temperature. A vapor pressure of 1 Torr is obtained at 168 °C, and thermal evaporation and decomposition begins from 250 °C and 425 °C, respectively. The Y₂O₃ film is fabricated by ALD technique using (iPrCp)₂Y(iPr-amd) and water as the precursors. The growth of the Y₂O₃ films is self-limited with an ALD window from 350 °C to 450 °C and a growth rate of 0.06 nm per cycle. The deposited Y₂O₃ film shows a polycrystalline cubic structure, higher refractive index of over 1.8 at 632.8 nm, and a high dielectric constant of 24. The as-deposited Y₂O₃ film is highly stoichiometric and constant in terms of Y and O through the depth, and it also includes small –OH bonds in the film without any additional processes. The Ru/Y₂O₃/Ru resistor shows resistance switching between the low and high resistance states with voltage sweeping, and the resistance ratio between the two states is more than 1000 times, which is preferable for non-volatile memory operation.