Capacitive Surface-Micromachined Pressure Sensors on Fused SilicaContributions to Micromachining on Fused Silica
Date Issued
2009-06-09
Author(s)
Supervisors
Referees
Abstract
Capacitive absolute pressure sensors fabricated by means of surface-micromachining on fused silica are presented. The non-conductive substrate material eliminates all parasitic capacitances to the bulk. Fabricated prototypes are simulated with SPICE and a lumped components model is derived. Simulation data is compared to wafer and package level test results. Touch-mode hysteresis, sensitivity, and magnitude of capacitance are discussed. Processing on fused silica is covered in detail with a focus on surface micromachining. Substrate material related process challenges are addressed such as high film stress levels as well as viscose and elastic deformation. Analytic formulas for surface-micromachined circular plates are presented. Topography, stress, and a limited displacement magnitude are considered by means of normalization. The approach leads to a solution for plates in touch-mode. General characteristics of capacitive circular plate transducers in normal- and touch-mode are discussed.
Subjects
surface micromachining
;
capacitive pressure sensor
;
fused silica
;
touch-mode
;
atmospheric reference
;
through substrate vias
;
silicon rich nitride
;
in-situ boron doped poly-silicon
;
circular plate deflection
;
film stress
;
Young's modulus
;
biaxial modulus
;
sacrificial etch selectivity
;
viscous deformation
;
sensor stability
;
sensor drift
;
hysteresis
Institution
Type
Dissertation
Secondary publication
No
Language
English
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