Formation of porous anodic alumina templates in selected micrometer-sized areas on a Si substrate. Application for growing ordered Ti nanopillars

Abstract

The local formation of porous anodic alumina (PAA) thin films on confined areas measuring few μm2 through an SiO2 masking layer on the silicon substrate has been developed. The locally grown porous anodic alumina thin films showed highly symmetric vertical cylindrical pores with a pore density that was much higher than that of films on non-confined areas. Pore density as high as 6 × 1010 pores/cm2 was achieved, compared to ∼1010 pores/cm2 in corresponding large-area samples. Pore diameter was as small as 30–50 nm. Alumina thin films on confined areas on a Si substrate are very interesting for use as masking layers for local Si nanopatterning or as templates for local growth of different nanostructures, e.g. nanowires of different materials, on wafer level. In this work, we used the PAA films as sacrificial templates to grow locally on a silicon wafer using sputtering, regular arrays of Ti nanopillars on pre-selected areas on the Si wafer. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)