Cantilever
beams are a commonly used MEMS structure. They consist of
long thin free standing beams anchored at one or both ends.
Microfabricated cantilever beams have many applications
including mechanical sensors and actuators, chemical sensing
and sensing, AFM probes, etc.
One
simple use of cantilever beams is to quantify the level of
strain in a thin film. With knowledge of Young’s Modulus for
the film, stress values can be obtained. Examples of strain gauges fabricated at NISRC
are illustrated in Figure 1. These are
polysilicon thin films, deposited on a sacrificial oxide.
Etching the underlying oxide releases the cantilever beams.
At this point, the stress in the film causes the beams to
deflect to the right or to the left. The deflection distance
is proportional to the stress; stress-free beams should remain
in their original position after release.
