Polymeric mask protection for alternative KOH silicon wet etching

A new cost-effective setup for silicon bulk micromachining is presented
which makes use of a polymeric protective coating, ProTEKR B2 coating,
instead of a conventional hardmask. Different concentrations of KOH and
bath conditions (pure, with surfactant, with stirrer, with both surfactant and
stirrer) have been considered. ProTEKR B2 coating exhibits good adhesion
to Si substrates, no degradation, etching rates and surface roughness
comparable to literature data, and etching times greater than 180 min
without damaging front side microstructures. Microcantilevers have also
been fabricated using two different process flows in order to demonstrate the
suitability of such a protective coating in microelectromechanical system
(MEMS) technology.