Maskless anisotropic etching-a novel micromachining technology for multilevel microstructures

The authors describe a novel bulk micromachining technology for silicon multilevel microstructures using a maskless etching following a masked etch in aqueous KOH. Deep multilevel structures with {311} sidewalls and <110> edges can be formed on a [001] silicon wafer and the number of levels is not limited in principle. The positions and the depths of individual levels are determined by the design for one mask and the masked-maskless etching process. The technology is likely to be very useful in micromechanical sensors and actuators.