Soft imprinting: Creating highly ordered porous anodic alumina templates on substrates for nanofabrication

We demonstrate a soft-imprinting method for the fabrication of highly ordered porous anodic alumina (HOPAA) templates on different substrates (such as Si, glass slides, and flexible polyimide films) over large areas (> 1.5 cm(2)). In this process, Ar plasma etching is employed to soft imprint an evaporated Al film on the substrates using a free-standing HOPAA template as a mask, thus creating ordered nanoindentations on the At surface. The ordered nanoindentat ions in turn guide the subsequent anodization of At to generate HOPAA templates on the substrates (HOPAA-substrates), which inherit the pattern of the freestanding HOPAA mask. This soft-imprinting technique is also applicable to the fabrication of HOPAA on flexible polymer films. To demonstrate the potential uses of the HOPAA-substrates in nanofabrication, highly ordered Au nanowire arrays are fabricated on a Si substrate and TiO2 nanotube arrays are prepared on a glass substrate via solution- and vapor-based fabrication processes, respectively.