Al2O3 Thin Films Prepared by a Combined Thermal-Plasma Atomic Layer Deposition Process at Low Temperature for Encapsulation Applications

In this article, a combined H2O thermal atomic layer deposition of Al2O3 with in situ N-2 plasma treatment process at 90 degrees C for encapsulation applications is reported. The effect of process parameters on the growth behavior and properties of Al2O3 thin films, such as elemental composition, residual stress, moisture permeation barrier ability, density, and roughness, is investigated. Optimization of plasma exposure time gives films with a low impurity (approximate to 3.8 at% for hydrogen, approximate to 0.17 at% for carbon, and approximate to 0.51 at% for nitrogen), a high mass density (approximate to 3.1 g cm(-3)), and a low tensile residual stress (approximate to 160 MPa). A water vapor transmission rate of 2.9 x 10(-3) g m(-2) day(-1) is obtained for polyethylene naphthalate substrates coated with 4-nm-thick Al2O3 films.