Stretchability of aluminum oxide film synthesized by plasma enhanced atomic layer deposition

Abstract

Amorphous structure aluminum oxide (Al2O3) films are used for various applications such as gas- and moisture-diffusion barriers. Al2O3 films deposited by atomic layer deposition (ALD) have good step coverage, high density and low surface roughness. However, these films contain more impurities and need longer processing time at lower growth temperatures. Plasma-enhanced ALD (PEALD) using trimethylaluminum (TMA) and O2 plasma was less dependent on temperature than thermal ALD. In this study, Al2O3 films were deposited by PEALD to protect flexible devices from moisture. By Griffith’s theory, the fracture strength of brittle materials reaches an ideal strength at a critical thickness. So in this study, we fabricated uniform and dense amorphous aluminum oxide film using plasma-enhanced ALD. We look at the critical thickness of amorphous Al2O3 films, which are brittle materials, and the changes in the mechanical behavior of amorphous Al2O3 when thickness is reduced. The push-to-pull in-situ tensile test was used here to measure mechanical properties of ultra-thin films. For sample preparation, Al2O3 films were deposited using ALD and thin-films were fabricated with dog-bone shape using focused ion beam(FIB).