MSI’s MEMS coatings are designed to provide the
following characteristics: covalently bonded monolayer, low surface
energy, low friction coefficient, thermally and mechanically stable.
While they mainly serve as anti-stiction coatings, these monolayers
also provide long term surface stability, thus eliminating surface related
drifting of device performance. Precursor molecules contain two major
parts, R & X. The R group is selected to provide low surface
energy, i.e., "wax" or "Teflon" like, while the
X group is chosen to selectively react with the solid surface of interest
for covalent linkage. The attachment of these molecules to the solid
surface is a kinetically controlled process; the reaction self-terminates
after a saturated monolayer coverage is reached. This is very different
from self-assembled monolayers (SAMs). Such a selective and controlled
reaction ensures that the coating is conformal with solid surfaces in
a MEMS device. The thickness of the coating is chosen to be 1-3 nm and
does not affect the mechanical properties of the MEMS structure.
