Process for integration of energetic porous silicon devices

Abstract

We have developed new procedures for etching porous silicon (PSi) which allow PSi devices to be more easily integrated with other devices used for controlling or utilizing the output of the PSi devices. The output from energetic PSi devices may be used for MEMS actuation or energy harvesting applications. Initial proof-of-concept energy harvesting with a macro-scale, piezo cantilever has been demonstrated. Of the 2 etch processes developed, the sacrificial electrode process is the simplest, but it produces an inhomogeneous PSi thickness across the wafer and introduces surface topography due to electropolishing. By using the anchored electrode method, which incorporates a dielectric layer, more controllable etch depths and patterned devices are obtained. However, a proximity effect is observed where features closer to the electrode etch more rapidly. A simple voltage divider model can be used to predict these relative etch depths, but more work is required to develop a quantitative model.