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

Abstract

In this article, a combined H2O thermal atomic layer deposition of Al2O3 with in situ N2 plasma treatment process at 90 °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 (≈3.8 at% for hydrogen, ≈0.17 at% for carbon, and ≈0.51 at% for nitrogen), a high mass density (≈3.1 g cm−3), and a low tensile residual stress (≈160 MPa). A water vapor transmission rate of 2.9 × 10−3 g m−2 day−1 is obtained for polyethylene naphthalate substrates coated with 4‐nm‐thick Al2O3 films.