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A High-Yield Microfabrication Process for Sapphire Substrate Capacitive Pressure Sensors Providing 70 MPa Range and 0.5 kPa Resolution.
- Source :
- IEEE Sensors Journal; 12/15/2021, Vol. 21 Issue 24, p27315-27324, 10p
- Publication Year :
- 2021
-
Abstract
- We report a high yield fabrication process based on surface micromachining of sapphire substrates and plasma-deposited thin films for pressure sensors with extraordinarily high output swing relative to baseline and parasitic capacitance. This feature allows the use of massively parallel diaphragms arrays in a single sensor chip that is read out with a single interface circuit, providing a superior full-scale range and resolution in a small footprint. Five types of sensor chips are reported, incorporating: a) a single diaphragm (ø 100 μm diameter); b) 18 diaphragms in parallel (ø 100 μm diameter); c) 85 diaphragms (ø56-ø 92 μm diameter); d) 8 diaphragms in parallel (ø 200 μm diameter); and e) 32 diaphragms in parallel (ø110-ø 150 μm diameter). The respective maximum gauge pressures are 30 MPa, 30 MPa, 70 MPa, 70 kPa, and 110 kPa; the respective resolutions are 1.0 kPa, 0.2 kPa, 0.5 kPa, 5.7 Pa, and 2.6 Pa. Full-scale range is defined with the upper boundary as the applied pressure at which the incremental response falls below 30% of the incremental response at the lower boundary (which is approximated as atmospheric pressure). In two of these cases, varying diameters are used to reduce the inherent non-linearity of the sensor response over the full-scale pressure range. The 85-diaphragm sensor, intended for downhole pressure sensing, provides a capacitance response of 0.46 fF/kPa and 7.1 pF C<subscript>0</subscript>. The 32-diaphragm sensor, intended for lower operating pressures, provides capacitance response of 29 fF/kPa and 11.5 pF C<subscript>0</subscript>. The fabrication process, design features, and experimental results are presented. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 1530437X
- Volume :
- 21
- Issue :
- 24
- Database :
- Complementary Index
- Journal :
- IEEE Sensors Journal
- Publication Type :
- Academic Journal
- Accession number :
- 154148820
- Full Text :
- https://doi.org/10.1109/JSEN.2021.3122280