Oxidation of Silicon Electrochemically Etched Microchannels Arrays

Macroporous silicon technology is an important method to fabricate microchannels on silicon. The formation of insulator layer on the sidewall of the channels is necessary for electrical isolation or passivation of the surface. Oxidation is one of the preferred options. In this paper we investigate the effect of various oxidation processes on the smoothness of the sidewalls of the high aspect ratio macropores. Using thermal oxidation with a combination of dry and wet steps, the shape and structures inside silicon microchannels can be changed after oxidation to certain thickness. To keep the surface inside the microchannels smooth, it is only possible to get oxide layer with limited thickness by oxidation in microchannel if the channel size is very small