The Mechanical Behaviour of Silicon Diaphragms for Micromachined Capacitive Pressure Sensor
| Periodical | Advances in Science and Technology (Volume 54) |
|---|---|
| Main Theme | Smart Materials & Micro/Nanosystems |
| Edited by | Pietro VINCENZINI and Giuseppe D'ARRIGO |
| Pages | 422-427 |
| DOI | 10.4028/www.scientific.net/AST.54.422 |
| Citation | Juan Ren et al., 2008, Advances in Science and Technology, 54, 422 |
| Online since | September, 2008 |
| Authors | Juan Ren, David Cheneler, Mike Ward, Peter Kinnell |
| Keywords | Capacitive Pressure Sensor, Circular Diaphragm, Orthotropic Property, Silicon |
| Price | US$ 28,- |
Single crystal silicon diaphragms are widely used as pressure sensitive elements in micromachined pressure sensors. When designing such a sensor it is usual to assume that the silicon is an isotropic material and the average elastic constants are used. However, the mechanical properties of single crystal silicon are orthotropic, and this has an important effect on the mechanical behaviour of silicon diaphragms under pressure. In this work, the deflections of orthotropic silicon circular diaphragms which are orientated against the (100) and the (110) planes are presented. It is found that by assuming silicon is isotropic material, the maximum stress is underestimated by 9.4% for (110) orientated silicon diaphragms, while the maximum stress is underestimated by 8% for (100) orientated silicon diaphragms. Therefore, when a silicon diaphragm is used in a MEMS sensor, the orthotropic properties should be taken into account for accuracy. Finally, the performance of a capacitive sensor is predicted by using finite element method.
