Several MEMS devices such as resonators, infrared sensors, and diaphragm
pressure sensors require vacuum sealed cavities to obtain excellent
sensitivity. From what I have been able to gather, it appears as though
non-evaporable getters (NEGs) such as those available from SAES are what is
usually used to combat adsorbed molecule outgassing over the life of a packaged
device.
Although the NEGs seem to be able to adsorb many gases quite effectively, they
are available only in ribbons and sheets, which are not amemable to wafer scale
processing.
Since the NEG is composed of a Ni/Cr ribbon covered with a porous mixture of Ti
and Zr-V-Fe alloy, I was wondering if anyone has had any experience or has seen
a reference where gettering material was applied to a surface using sputtering,
evaporation, screen printing, spin coating, or any other technique that could
be used to coat the surface of a silicon wafer. Any information / advice /
leads are greatly appreciated.
Brian Cunningham
Draper Laboratory
Cambridge, MA