Electrothermal Actuators Fabricated from Single Crystal
John M. Maloney, Don L. DeVoe, and David S. Schreiber
IMECE 2000 (ASME Annual Winter Meeting), Orlando, FL.
Thermal actuators that deflect laterally by resistive
heating have been fabricated in single crystal silicon (SCS)
by deep reactive ion etching. With heights of 50 microns,
these high-aspect actuators produce significantly larger
forces than similar polysilicon devices. Problems with
stiction are also avoided through the use of silicon-on-insulator
(SOI) technology. An analytical model is applied to U-beam
and V-beam actuator shapes fabricated on SOI wafers. The
electrothermal component of the analysis uses an axial
conduction model to predict temperature distribution; the
thermomechanical component employs elastic beam theory to
calculate deflection due to thermal strain. Experimental
results are compared to analytical predictions.
Deflections of 29 microns for a 1200 micron long, 12 micron wide
actuator were observed, corresponding to a predicted
force of 7.6 mN.