Integrated sensors for process monitoring and health monitoring in microsystems
Abstract
This thesis presents the development of integrated sensors for health monitoring
in Microsystems, which is an emerging method for early diagnostics of status or
“health” of electronic systems and devices under operation based on embedded
tests. Thin film meander temperature sensors have been designed with a
minimum footprint of 240 m × 250 m. A microsensor array has been used
successfully for accurate temperature monitoring of laser assisted polymer
bonding for MEMS packaging. Using a frame-shaped beam, the temperature at
centre of bottom substrate was obtained to be ~50 ºC lower than that obtained
using a top-hat beam. This is highly beneficial for packaging of temperature
sensitive MEMS devices. Polymer based surface acoustic wave humidity sensors
were designed and successfully fabricated on 128° cut lithium niobate substrates.
Based on reflection signals, a sensitivity of 0.26 dB/RH% was achieved between
8.6 %RH and 90.6 %RH. Fabricated piezoresistive pressure sensors have also
been hybrid integrated and electrically contacted using a wire bonding method.
Integrated sensors based on both LiNbO3 and ZnO/Si substrates are proposed.
Integrated sensors were successfully fabricated on a LiNbO3 substrate with a
footprint of 13 mm × 12 mm, having multi monitoring functions for simultaneous
temperature, measurement of humidity and pressure in the health monitoring
applications.