Thickness Mediated Morphology Evolution in Sub-10-nm Metal Film Deposition: Implications for Nondestructive Testing

High Resolution Image Download MS PowerPoint Slide Thickness in sub-10-nm metal film deposition is a seldom explored parameter that can influence not only the film mechanical properties but also the surface functional characteristics. In this study, we designed bilayer systems comprising Au on a poly(dimethylsiloxane) (PDMS) substrate to reveal a unique thickness-mediated surface morphology evaluation phenomenon. Our results show that, within a specific range of elastic modulus of the selected PDMS substrate, surface wrinkling starts when the deposited theoretical Au thickness is around 0.2 nm, reaches a maximum deformation at thickness 1–2 nm, and disappears when the thickness is equal to or larger than 8 nm. The thickness-mediated wrinkling on and off suggest that film thickness can strongly impact the patterns observed on soft elastomers. This finding indicates that what we observed may not be the intrinsic surface properties but rather thickness-controlled wrinkling. Using 2 nm Au deposition as a highly sensitive nondestructive testing method, a potential application for identifying surface defects on solid surfaces is proposed.