Influence of plasma parameters on the properties of ultrathin Al2O3 films prepared by plasma enhanced atomic layer deposition below 100 degrees C for moisture barrier applications

We report the effect of plasma parameters on the properties of ultrathin Al2O3 films prepared by plasma enhanced atomic layer deposition for moisture barrier applications. The Al2O3 films were grown at 90 degrees C using trimethylaluminum and O-2 plasma as precursors. Plasma power, exposure time and O-2 concentration are found to influence the growth behavior, composition and density of ultrathin Al2O3 films. Plasma power >= 100W leads to lower impurity levels and higher mass densities of similar to 2.85g.cm(-3). The optimum plasma parameters for our process, a plasma power of 100W and an exposure time of 3 s, reveal a good water vapor transmission rate of 5 x 10(-3)gm(-2).day(-1) for polyethylene naphthalate substrates coated with 4 nm-thick Al2O3 films. (C) 2018 The Japan Society of Applied Physics