Electrochemical process for micropattern transfer without photolithography: a modeling analysis

A concept of maskless electrochemical microfabrication has been presented. In this method, a substrate, which is the anode, is placed in an electrochemical reactor in close proximity to a tool carrying the micropattern, which is the cathode. Although the anode is etched over its entire surface, it etches at a higher rate on the areas opposing exposed regions of the cathode, hence, reproducing a pattern on the anode. This paper describes the electrochemical process that enables the transfer of micropatterns from the cathode to the anode. This investigation involved the development of a mathematical model for anodic dissolution from a substrate, which was tested and verified against experimental data. The model was solved using commercial software that allows the simultaneous solution of reaction distribution at two different length scales, millimeter and micrometer. It has been applied to copper dissolution in acidified and nonacidified media. The results show that selective etching in acidified media produces a surface topography that is sinusoidal, whereas a rectangular topography is obtained in nonacidified media due to the formation of an oxide at the surface.