Process for integrating porous silicon with other devices

Newly developed electrochemical etch procedures facilitate the integration of energetic porous silicon (PSi) with other devices. By confining the PSi etch process to one side of the wafer, devices on the other side of the wafer may be protected from the harsh etch conditions. This allows PSi integration with devices used for triggering or utilizing the energetic output of the PSi. The output from energetic PSi devices may be used for fusing, microthruster, MEMS actuation or other applications. Two different etch processes were developed: the sacrificial electrode process is the simplest, but it results in nonuniform PSi thickness and introduces surface topography. The anchored electrode method, which incorporates a dielectric layer, results in more controlled etch depths and allows the facile formation of patterned devices. However, in either process, a proximity effect is observed which results in deeper PSi etching closer to the electrode(s) driving the etching. A simple current divider model can be used to predict these relative etch depths. The resulting PSi burn properties have been characterized and are similar to those obtained with the previous process.