16 August 2001 Capacitive micropressure sensors with underneath readout circuit using a standard CMOS process
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A capacitive micropressure sensor with readout circuits on a single chip is fabricated using commercial 0.35micrometers CMOS process technology and post-processing. The main break through feature of the chip is the positioning of its readout circuits under the pressure sensor, allowing the chip to be smaller. Post-processing included anisotropic dry etching and wet etching to remove the sacrificial layer, and the use of PECVD nitride to seal the etching holes of the pressure sensor. The sacrificial layer was the metal 3 layer of the standard 0.35 micrometers CMOS process. In addition, the readout circuit is divided into analog and digital parts, with the digital part being an alternate coupled RS flip- flop with four inverters that sharpened the output wave. Moreover, the analog part is employed switched capacitor methodology. The pressure sensor contained an 8 X 8 sensing cells array, and the total area of the pressure sensor chip is 2mmx2 mm. In addition to illustrating the design and fabrication of the capacitive pressure sensor, this investigation demonstrates the simulation and testing results of the readout circuit.
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Shihchen Chang, Chingliang Dai, Jinghung Chiou, Peizen Chang, "Capacitive micropressure sensors with underneath readout circuit using a standard CMOS process", Proc. SPIE 4334, Smart Structures and Materials 2001: Smart Electronics and MEMS, (16 August 2001); doi: 10.1117/12.436619; https://doi.org/10.1117/12.436619

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