Fabrication of a membrane type double cavity vacuum‐sealed micro sensor for absolute pressure based on front‐side lateral etching technology

Rathore, Pradeep; Akhtar, Jamil

doi:10.1108/02602281111099071

Cited by 6 publications

(4 citation statements)

References 11 publications

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“…The fabrication process of double cavity vacuum sealed piezoresistive pressure sensor using front-side lateral etching technology has been described in details in the previous work (Rathore and Akhtar, 2011). A six-mask process has been developed to fabricate the sensor with major process flow shown in Figure 2.…”

Section: Pressure Sensor: Fabrication and Testingmentioning

confidence: 99%

“…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%

“…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%

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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: Pressure Sensor: Fabrication and Testingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2013

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“…These diaphragms are relatively simple to fabricate, and their analytical solutions of displacement profiles and stress distributions under load are well developed (Bao, 2005). Silicon micromachining processes have been well developed and are being extensively used for the fabrication of thin diaphragms and realization of microcavities from back and front side of silicon wafer for MEMS pressure sensors (Rathore and Akhtar, 2011;Peng et al, 2005;Kressmann et al, 2002). The deflection of these micromachined diaphragms under applied pressure can be sensitively monitored by means of a variety of transduction mechanisms such as piezoresistivity, piezoelectricity, capacitive method, optical detection and beam resonant method (Smith, 1954;Ko, 2003;Lee and Wise, 1982;Benaissa and Nathan, 1996;Ikeda, 1990).…”

Section: Introductionmentioning

confidence: 99%

A novel CMOS-MEMS integrated pressure sensing structure based on current mirror sensing technique

Rathore

Panwar

Akhtar

2015

Microelectronics International

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Purpose -The present paper aims to propose a basic current mirror-sensing circuit as an alternative to the traditional Wheatstone bridge circuit for the design and development of high-sensitivity complementary metal oxide semiconductor (CMOS)-microelectromechanical systems (MEMS)-integrated pressure sensors. Design/methodology/approach -This paper investigates a novel current mirror-sensing-based CMOS-MEMS-integrated pressure-sensing structure based on the piezoresistive effect in metal oxide field effect transistor (MOSFET). A resistive loaded n-channel MOSFET-based current mirror pressure-sensing circuitry has been designed using 5-m CMOS technology. The pressure-sensing structure consists of three identical 10-m-long and 50-m-wide n-channel MOSFETs connected in current mirror configuration, with its input transistor as a reference MOSFET and output transistors are the pressure-sensing MOSFETs embedded at the centre and near the fixed edge of a silicon diaphragm measuring 100 ϫ 100 ϫ 2.5 m. This arrangement of MOSFETs enables the sensor to sense tensile and compressive stresses, developed in the diaphragm under externally applied pressure, with respect to the input reference transistor of the mirror circuit. An analytical model describing the complete behaviour of the integrated pressure sensor has been described. The simulation results of the pressure sensor show high pressure sensitivity and a good agreement with the theoretical model has been observed. A five mask level process flow for the fabrication of the current mirror-sensing-based pressure sensor has also been described. An n-channel MOSFET with aluminium gate was fabricated to verify the fabrication process and obtain its electrical characteristics using process and device simulation software. In addition, an aluminium gate metal-oxide semiconductor (MOS) capacitor was fabricated on a two-inch p-type silicon wafer and its CV characteristic curve was also measured experimentally. Finally, the paper presents a comparative study between the current mirror pressure-sensing circuit with the traditional Wheatstone bridge. Findings -The simulated sensitivities of the pressure-sensing MOSFETs of the current mirror-integrated pressure sensor have been found to be approximately 375 and 410 mV/MPa with respect to the reference transistor, and approximately 785 mV/MPa with respect to each other. The highest pressure sensitivities of a quarter, half and full Wheatstone bridge circuits were found to be approximately 183, 366 and 738 mV/MPa, respectively. These results clearly show that the current mirror pressure-sensing circuit is comparable and better than the traditional Wheatstone bridge circuits. Originality/value -The concept of using a basic current mirror circuit for sensing tensile and compressive stresses developed in micro-mechanical structures is new, fully compatible to standard CMOS processes and has a promising application in the development of miniaturized integrated micro-sensors and sensor arrays for automobile, medical and industrial application...

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Pressure sensor based on bipolar discharge corona configuration

Dau

Thanh

Dinh

et al. 2016

Sensors and Actuators A: Physical

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Fabrication of a membrane type double cavity vacuum‐sealed micro sensor for absolute pressure based on front‐side lateral etching technology

Cited by 6 publications

References 11 publications

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

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

A novel CMOS-MEMS integrated pressure sensing structure based on current mirror sensing technique

Pressure sensor based on bipolar discharge corona configuration

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