Controlled surface topography of nanofilm by local strain modulation in mechanical transfer process

Abstract

The mechanical transfer of nanofilms has been successfully established based on interfacial delamination behaviors. However, controlling the formation of surface cracks and wrinkles in nanofilms during mechanical transfer processes remains a challenge. Here, we demonstrate the controlled surface topography of nanofilms using local strain in the mechanical transfer process. A single cantilever beam (SCB) fracture mechanics test is performed using a specimen composed of an elastomer receiver–Au nanofilm–Si donor structure to investigate the variation in the surface topography of a transferred nanofilm with respect to the receiver thickness, loading angle, and loading rate. The results indicate that owing to the reduction of the tensile strain at the crack tip, the crack density in the nanofilm decreases when a thick elastomer, high loading angle, and low loading rate are applied during the transfer process. Furthermore, beyond the reduction in the tensile strain, the use of a rigid receiver generates a compressive strain at the crack tip, resulting in wrinkles in the nanofilm without cracks. The mechanisms of surface cracking and wrinkling are elucidated by analyzing the strain distribution at the crack tip via numerical simulation. We believe that this study can potentially contribute to advancements in mechanical transfer technology.