Fabrication of Ideally Ordered Anodic Porous Alumina on Glass Substrates by Stamping Process Using Flexible Stamps

Abstract

Establishing a process to fabricate anodic porous alumina with an ordered array of uniformly-sized pores on a substrate is an important challenge in fabricating various functional devices. In this study, ordered anodic porous alumina was fabricated on glass substrates by a stamping process using a flexible stamp. This process enables the formation of a resist mask at a low pressure on the sample surface to pattern the starting point for pore generation during anodization. Therefore, it is possible to pattern samples without breaking the glass substrate, and subsequent anodization can generate ordered anodic porous alumina on the substrate. The stamping process using flexible stamps can be applied regardless of the roughness of the Al film on a substrate because the stamp deforms according to the Al surface shape, even when there is a protruding structure on the Al surface. In addition, it was shown that this process could be used to form ordered anodic porous alumina even on Al surfaces with three-dimensional curvatures, such as convex lenses.

Preparation of Alumina Membrane Filters with Framework Structures by Al Anodization

“…As the thickness of the resulting anodic porous alumina corresponds to that of the framework layer, the thickness of the framework was controlled in the range of 30–100 μm by varying the anodization time. A resist mask was formed on the ordered anodic porous alumina using a poly­(dimethylsiloxane) (PDMS) stamp with a square array of micrometer-sized convex patterns (Figure (b)). , The PDMS stamp was prepared by molding an original pattern fabricated by electron beam lithography as a template. To form the resist film on the surface of the PDMS stamp, the stamp was immersed in a toluene solution containing 0.5 wt % polychloroprene at 30 °C, held for 10 s, and then pulled up at a constant speed of 0.5 mm s –1 using a desktop dip coater (DC4200, Aiden, Japan).…”