Low temperature ( < 100 deg C) deposition of aluminum oxide thin films by ALD with O3 as oxidant

Al2O3 films were deposited by atomic layer deposition(ALD) using trimethylaluminum and O3 as precursor and oxidant, respectively, at growth temperatures ranging from room temperature to 300 deg C on Si(100) substrates. Growth rate and refractive index of the Al2O3 films decreased from 0.20 to 0.08nm/cycle and increased from 1.52 to 1.65, respectively, with increasing growth temperature. The dielectric constant slightly increased from 6.8 to 8 with increasing growth temperature in the same temperature range. Al2O3 films grown using O3 as oxidant show a smaller hysteresis, lower leakage current density, and higher breakdown field strength compared to those using H2O as oxidant at the same growth temperature. X-ray photoelectron spectroscopy showed that the films grown at lower temperatures have a smaller bandgap energy. The Al2O3 films grown at a temperature as low as 100 deg showed reasonable dielectric properties for dielectric film applications on flexible substrates.