Nano-fabrication of stretchable encapsulation films with silicon dioxide film thermally grown on silicon wafer

Abstract

As interest in stretchable devices is increasing, researches on stretchable optoelectronic devices being vulnerable to moisture and oxygen are also being activated. To protect from moistures in air, materials with zero defect and high density such as glass, commonly used encapsulation layer, is required. For this purpose, thermally grown silicon dioxide film having high density and rare defects is expected to show ultra-low water transmission. As silicon dioxide film shows very brittle behavior like other metal oxide materials, this film can’t be applied on stretchable devices with its own elastic property. In this research thermally grown dioxide film was used to show low water transmission and thickness effect and wrinkled structure were applied on silicon dioxide film to increase stretchability. To fabricate thermal oxide encapsulation film, wet etching and dry etching processes were used to remove silicon and polymer layer was coated on the silicon dioxide to avoid damage. Wrinkled structures were fabricated by using a difference between thermal expansion coefficients of two films. The relationship between mechanical properties of film and structure of wrinkle was discussed by measuring mechanical properties of submicron-thick freestanding silicon dioxide film, to have optimistic film thickness satisfying high stretchability and stable structure.