Formation of metal-metal oxide patterns using masked light-induced anodization

A selective patterning technique using light-induced anodization (LIA) of a masked metal surface is reported. The method can be used to form metal patterns under masked regions whilst the unmasked regions are anodized to create an anodic metal oxide dielectric layer. The through-wafer current flow in LIA allows the anodization process to be modelled as an array of resistors in series with the solar cell. In this paper, such a model was used to confirm that residual metal remains adjacent to the mask thereby limiting the resolution of the selective anodization process. It is shown that thinner metal layers and larger anodic currents can result in higher pattern resolution. Coupled with the use of a higher resolution masking method with smaller/thinner masked regions, it should therefore be possible to form higher resolution metal-dielectric patterns that can be used for seed layer metal applications.