Certain designs for frustrated total internal reflection fiber optic evanescent wave sensors (FTIR FOEWS) include the
partial removal of cladding along a finite length of the fiber optic that acts as the sensing region. This paper presents a
model for a FTIR FOEWS that has a thin, partial cladding in the sensing region. Since the thickness of the cladding in
the sensing region is in the 1 μm range, while the propagating light is on the order of 850 nm, commonly used ray optic
modeling techniques fail to properly simulate the thin film interference effects. In this study, a modification to the usual
ray model is performed by including thin film optic analysis at the thin film sensing interface. The resulting hybrid
ray/thin film model maintains the efficiency of previously reported models, but also adds the ability to fully model the
partial cladding of the sensing region. The intensity and angular distributions of light from a Lambertian LED source
onto the fiber input face is also derived to discuss the effects of launching conditions on the sensor performance.
Investigation of a variety of meridional propagation ray distributions into the fiber are performed by varying the distance
and angle of the point source to the fiber input face. Optimal cladding thicknesses, LED distance and tilt angle are
studied and used to draw conclusions about FTIR FOEWS performance based on launching conditions.
An investigation into the effects of dry plasma etching release process parameters, local wafer position and induced inplane
stress on the yield of MEMS devices is presented. Several identical wafer quarters, each subjected to different
releasing process conditions, are studied. Yield is evaluated by observational measurements of the stiction of MEMS
nanocantilevers fabricated alongside with bent beam strain sensors. Results show that lower yield is found for larger
processing times as well as higher releasing temperatures. On the other hand, yield improves when thicker
nanocantilevers are released using the same processing parameters. The distribution of process-induced in-plane stress of
PECVD silicon nitride films is shown to change widely from compressive to tensile based on the local wafer position,
whereas no clear correlation between stiction and stress distribution is found. Viability of determining MEMS yield at
the wafer-level based on process-induced residual stress is discussed. Other possible root causes of yield in MEMS due
to dry plasma release etching are also briefly touched.