Young's Modulus Characterization of Nano-Level Silicon Nanomembrane

Abstract

Silicon nanomembrane (SiNM) has drawn great attention for the application in nanoelectrical devices as it shows excellent flexibility and is compatible with the integrated circuit process. The mechanical property measurement of the SiNM with nano scale thickness is critical. A suspended SiNM (40 nm-thick) for mechanical measurements was fabricated by transferring a chemically etched ultra-thin monocrystalline silicon film from silicon on insulator wafer to a substrate with a multi-hole array. And then the atomic force probe was utilized to load force on the free-satnding SiNM to obtain a force deflection curve, and then the Young’s modulus of such floating SiNM can be directly calculated based on the large deflection plane model. It shows that the Young’s modulus of such SiNM is basically consistent with that of the bulk silicon. However, the SiNMs’ floating area significantly affects the results, i.e. the Young’s modulus varies with the ratio of the suspended area diameter (i. e. hole diameter) to the film thickness. The Young's modulus is independent of hole diameter only when the ratio is greater than 375. According to this relationship, the variation of Young's modulus can be predicted for arbitrary thick SiNMs and any transferable nanofilms.

Keywords: Atomic force probe, silicon nanomembrane, Young's modulus, suspended nanomembrane