Pressure Sensor Die
- Surface micromachined capacitive absolute pressure sensor fabricated on non-conducting fused silica
- Very small die size (0.6x1.2 mm², height 0.48 mm)
- 0.5 to 1.3 and 1.2 to 8.0 bar measuring range
- Very high input resistance >300 MΩ
- Overpressure >>9 bar causes no damage
- Floating capacitance
- Large bond pads for conductive adhesive mount Membrane counter electrode with dielectric insulation
The ultra small surface micromachined capacitive sensor element aims at all applications where size and low power-dissipation matters that are medical and wireless systems as well as industrial transducers. The special choice of fused silica as a nonconducting substrate material results in the elimination of all parasitic capacitances to the substrate. This implies strong advantages for sensor design, fabrication and application. The remaining parasitic capacitance can be controlled via mask design, changes in wiring layout do not impact sensor performance, hence offset capacitance and contact geometry can be designed according to customer specifications.
Large bond pads allow a chip mount by means of conductive adhesive which does not cause parasitic capacitances. Furthermore the sensor is a floating capacitance and no substrate contact is necessary. The transparent substrate allows optical monitoring of the packaging process. Design options include wider non-metallic conductor tracks for high temperature applications.