Thickness-dependent tensile behavior of thermally-grown SiO2

Abstract

Silicon dioxide film can be used as components in devices such as insulator and encapsulation material because it has high electrical resistivity and low water permeability. Although stretchable organic devices have been widely studied, we found that researches related to stretchable SiO2 are insufficient, so we studied stretchable SiO2 film. Many researchers have increased stretchability by applying wrinkles on films. To design wrinkle structure of SiO2, mechanical properties of a SiO2 thin film were required. Because critical strain on wrinkled SiO2 should be lower than yield strain of flat SiO2 film. In this research, we performed tensile tests of 100, 200 and 500 nm-thick freestanding thermally grown SiO2 thin films and analyzed thickness-dependence. We fabricated micro-scale samples using focused ion beam technique and attached to a push-to-pull device using manipulation system. To observe tensile behaviors precisely, in-situ tensile tests were performed using pico-indenter installed in SEM.