Working gas effect on properties of Al2O3 film in plasma-enhanced atomic layer deposition

Abstract The effect of working gas on the properties of Al 2 O 3 films and SiO x interlayers was investigated in direct-type plasma-enhanced atomic layer deposition. The density of the Al 2 O 3 film was higher for Ar/O 2 plasma than for He/O 2 plasma, whereas the thicknesses of the Al 2 O 3 film and SiO x interlayer were greater for He/O 2 plasma than for Ar/O 2 plasma. For understanding these phenomena, the amounts of C– and H-containing impurities in the deposited Al 2 O 3 film were evaluated by using X-ray photoelectron spectroscopy (XPS). Further, differences between the plasma properties in He/O 2 and Ar/O 2 were analyzed using optical emission spectroscopy (OES); the consumption rate of O radicals and the production rate of H radicals were estimated from the time-resolved emission intensities for the O I and H α lines, respectively. The mechanisms underlying the working gas effect on the density of the Al 2 O 3 film, as well as the thicknesses of the Al 2 O 3 film and SiO x interlayer have also been discussed.