Parameters influencing the flatness and stability of capacitive pressure sensors fabricated with wafer bonding

In this work we present detailed optical and electrical characterization results on silicon capacitive pressure sensing elements. The device fabrication technology is based on the wafer bonding technique. Using the micro-Raman technique, we investigate the influence of specific process steps as well as of the wafer bonding conditions-performed either in air or in nitrogen ambient-on the flatness and stress distribution of the pressure sensing diaphragms. Emphasis is also given on drift as well as on fatigue measurements since these effects determine the reliability of the devices. (C) 1999 Elsevier Science S.A. All rights reserved.