Study On The Fabrication Of Micro-nano Nested Wrinkles Under Boundary Effect

Traditional micro-nanofabrication process often uses lithography, etching and other micro-nano manufacture processing, which is generally higher cost and complex means of processing, Film/substrate structure is instability when subjected to a compressive stress, and if the value of the strain reaches to a critical value, buckling occur. According to the mechanical simulation of wrinkles, researchers find that, by controlling the process parameters, it is possible to change the appearance of wrinkles including wavelength and amplitude parameters and also create wrinkles to reach micro- and nanostructures. This process generally use simple physical deformation to obtain micro-nano structures, and has controllable structure, lower processing costs, enabling large-scale production and other characteristics, which provides widely used in bionic research, flexible electronics and other fieldsIn this paper, two ways to generate stress and strain are given: pre-stretching and thermal expansion method to create nano-scale wrinkles. We research the morphology and size of nested wrinkles by Combining the hierarchical nested wrinkles and boundary effect theory, which provides a new method and idea of micro-nanofabrication technology. Specific studies include:First, use pre-stretching method to provide stress and strain. Stretching Polydimethylsiloxane(PDMS) elastic substrate in a unidirectional way, and create a hard oxide-film on the surface of substrate by plasma oxidation. micro-nano wrinkles structure occur when stress is released. The wrinkles obtained in this way are sine-wave structure liked, and the direction of wrinkles is perpendicular to the stretching direction. By changing the oxidation time and the value of stretching, studies the relationship between wrinkles wavelength, amplitude and the process parameters.Second, obtain stress and strain by way of thermal expansion. Treat PDMS elastic material as substrate, and depositing a copper film by sputtering process on the substrate. Using a silicon mask control the deposition area of film during the sputtering process. The morphology of copper film is narrow band liked. After cooling, the stress has been released and nested hierarchical wrinkles occur. The nested hierarchical wrinkles have two layers, including a regular morphology of sine-wave micron-wrinkles and nano morphology of labyrinth wrinkles.Third, analyze the formation mechanism of hierarchical nested wrinkles. The boundary effect explains why the morphology of micron-wrinkles are regular sine-wave. By increasing the width of the silicon mask, the width of boundary is also increased. Changing the film thickness in thermal expansion process, studies the relationship between film thickness and wavelength, amplitude of the nested hierarchical wrinkles.