Capacitive Absolute Pressure Sensor with Vacuum Cavity Formed by Bonding Silicon to Soiwafer for Upper Air Observations

Lee, K.R.; Kim, K.; Kim, Y.K.; Park, H.D.; Choi, S.W.; Choi, W.B.; Ju, Byung-Kwon

doi:10.1109/memsys.2006.1627875

Cited by 1 publication

(1 citation statement)

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“…The current issue and full text archive of this journal is available at www.emeraldinsight.com/0260-2288.htm a diaphragm and then the silicon wafer is bonded with another wafer to form a vacuum-sealed cavity below the diaphragm (Lee et al, 2006;Parameswaran et al, 1995). Absolute pressure sensor based on vacuum sealed microcavities has been recently developed by employing front-side lateral etching technique, avoiding the use of an extra wafer and the bonding process (Rathore and Akhtar, 2011).…”

Section: Introductionmentioning

confidence: 99%

Finite element method based absolute pressure sensitivity optimized membrane type double cavity vacuum sealed piezoresistive sensor

et al. 2013

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Purpose -The purpose of this paper is to use finite element method for optimizing the membrane type double cavity vacuum sealed structure for the best achievable sensitivity in a piezoresistive absolute pressure sensor and its validation using a standard complementary metal oxide semiconductor (CMOS) process. Design/methodology/approach -A double cavity vacuum sealed piezoresistive absolute pressure sensor has been simulated and optimized for its performance and an analytical model describing the behaviour of the sensor has been described. The 1 £ 1 mm sensor chip has two membrane type 100 £ 30 £ 1.7 mm diaphragms consisting of composite layers of plasma enhanced chemical vapour deposition (PECVD) of silicon nitride (Si 3 N 4 ) and silicon dioxide (SiO 2 ) each hanging over 21 mm deep rectangular cavity. Potassium hydroxide (KOH) based anisotropic etching of single crystal silicon using front side lateral etching technology is used for the fabrication of the sensor. The electrical readout circuitry uses 318 V boron diffused low pressure vapour chemical vapour deposition (LPCVD) of polysilicon resistors arranged in the Wheatstone half bridge configuration. The sensing structure is simulated and optimized using COMSOL Multiphysics. Findings -Front-side lateral etching technology has been successfully used for the fabrication of double cavity absolute pressure sensor. A good agreement with the fabricated device for the chosen location of the piezoresistors through simulation has been predicted. The measured pressure sensitivity of two tested pressure sensors is 12.63 and 12.46 mV/MPa, and simulated pressure sensitivity is found to be 12.9 mV/MPa for pressure range of 0 to 0.5 MPa. The location of the piezoresistor has also been optimized using the simulation tools for enhancing the sensor sensitivity to 62.14 mV/ MPa. The pressure sensitivity is further enhanced to 92 mV/MPa by increasing the width of the diaphragm to 35 mm. Originality/value -The simulated and measured pressure sensitivities of the double cavity pressure sensor are in close agreement. Sevenfold enhancement in the pressure sensitivity of the optimized sensing structure has been observed. The proposed front-side lateral etching technology can be adopted for making membrane type diaphragms hanging over vacuum sealed micro-cavities for high sensitivity pressure sensing applications.

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Section: Introductionmentioning

confidence: 99%