The first reported CMOS-MEMS processes produce
microstructural sidewalls by stacking the draidsource contact
cut and metal via cuts in the CMOS and removing the
metallization layers above the cuts [13]. The substrate is
exposed in the cut regions. A wet or dry isotropic silicon
etch undercuts and releases the microstructures. Gaps
between microstructures are limited to several microns
because of artifacts in the etch pits from etching metal
above the CMOS contacts. Such microstructures are commonly
used to make thermally isolated and vertically actuated
structures integrated with electronics.