With progressing monolithic integration of entire Microelectromechanical systems (MEMS) on one chip fabricated by standard IC technology we have to cope with the problem that the operation of embedded transducer elements is considerably affected by touch-down effect, cross-coupling and parasitic effects. Referring to a NCMOS-integrated capacitive pressure sensor as an illustrative example, we demonstrate that a touch-down effect analysis on the device level is indispensable to understand the interplay of various effects, which contribute to the sensor output. On the basis of this analysis we are able to build a physically-based macro model for the predictive simulation of the system performance.
Progressing
integration of entire Microelectromechanical systems (MEMS)
on single chip fabricated by industrial standard IC technologies
as used in microelectronics often leads to device structures
of high complexity. Since their fabrication is subjected to
specific process and design rules, e.g., predefined layer
sequences or doping profiles in the substrate, parasitic structures
and entering device into non-linear zone of the characteristics
cannot be avoided which affect the sensor signal and are not
separable from it by measurements alone.
Therefore,
a dedicated analysis on device and system level is required
to identify all effects contributing to the sensor signal,
to get comprehensive insight into the device behavior, performance
evaluation and eventually to calibrate the device [1]. Detailed
device studies should then lead to physically based compact
models, which enable the device engineer to perform predictive
simulations for design optimization [2]. |
