A thermopile based SOI CMOS MEMS wall shear stress sensor

Luca, Andrea De; Haneef, Ibraheem; Coull, John D.; Ali, Syed Zeeshan; Falco, Claudio; Udrea, F.

doi:10.1109/smicnd.2013.6688088

Cited by 7 publications

(9 citation statements)

References 16 publications

(19 reference statements)

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“…Dies were taken from different areas across the same wafer and separately packaged onto CPGA packages. Excellent reproducibility of the hot-wire electro-thermal behaviour as well as the thermopiles' output voltages in response to hot-wire heat stimulus was reported [29]. In Fig.…”

Section: Device Characterizationmentioning

confidence: 64%

“…Thermal wall shear stress sensors are traditionally based on anemometric transduction principle (exceptions are the sensors proposed by [28] and [29]). Different materials for the heating/sensing element have been explored (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…polysilicon [17], [18], [20]- [23], aluminum [24], tungsten [29], gold [25], platinum [19], nickel [26], laterally aligned carbon nano tubes [27]) as well as a diversity of thermal isolation schemes have been proposed (e.g. polyimide filled KOH-etched trench [17], surface micro-machined vacuum cavity [18], wafer-bonded vacuum cavity [19] and DRIE air cavity [5], [24], [29], [31]). However, except for a limited number of cases [22]- [24], [29], [31], CMOS compatible fabrication processes are not employed, posing high manufacturing costs and inhibiting on-chip circuitry integration.…”

Section: Introductionmentioning

confidence: 99%

“…polyimide filled KOH-etched trench [17], surface micro-machined vacuum cavity [18], wafer-bonded vacuum cavity [19] and DRIE air cavity [5], [24], [29], [31]). However, except for a limited number of cases [22]- [24], [29], [31], CMOS compatible fabrication processes are not employed, posing high manufacturing costs and inhibiting on-chip circuitry integration.…”

Section: Introductionmentioning

confidence: 99%

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High-Sensitivity Single Thermopile SOI CMOS MEMS Thermal Wall Shear Stress Sensor

et al. 2015

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In this paper, we present a novel silicon-on-insulator (SOI) complementary metal-oxidesemiconductor (CMOS) microelectromechanical-system thermal wall shear stress sensor based on a tungsten hot-wire and a single thermopile. Devices were fabricated using a commercial 1-µm SOI-CMOS process followed by a deep reactive ion etching back-etch step to release a silicon dioxide membrane, which mechanically supports and thermally isolates heating and sensing elements. The sensors show an electrothermal transduction efficiency of 50 µW/°C, and a very small zero flow offset. Calibration for wall shear stress measurement in air in the range of 0-0.48 Pa was performed using a suction type, 2-D flow wind tunnel. The sensors were found to be extremely sensitive, up to 4 V/Pa for low wall shear stress values. Furthermore, we demonstrate the superior signal-to-noise ratio (up to five times higher) of a single thermopile readout configuration compared with a double thermopile readout configuration (embedded for comparison purposes within the same device). Finally, we verify that the output of the sensor is proportional to the cube root of the wall shear stress and we propose an accurate semiempirical formula for its modeling.Index Terms-Wall shear stress, hot-film, thermopile, silicon-on-insulator, complementary metal oxide semiconductor, micro-electro-mechanical-systems.

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Section: Device Characterizationmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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High-Sensitivity Single Thermopile SOI CMOS MEMS Thermal Wall Shear Stress Sensor

et al. 2015

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“…Flow sensors are extensively used for flow measurements in diverse applications in different fields including aerospace [1,2,3,4,5,6], automotive [7], biomedical [8,9,10,11], environmental [12,13,14,15,16,17], hydrodynamics [18] and the chemical and process industries [19]. They can be broadly classified as either non-thermal or thermal [20].…”

Section: Introductionmentioning

confidence: 99%

Sensitivity Enhancement of Silicon-on-Insulator CMOS MEMS Thermal Hot-Film Flow Sensors by Minimizing Membrane Conductive Heat Losses

Mehmood

Haneef

Ali

et al. 2019

Sensors

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Minimizing conductive heat losses in Micro-Electro-Mechanical-Systems (MEMS) thermal (hot-film) flow sensors is the key to minimize the sensors’ power consumption and maximize their sensitivity. Through a comprehensive review of literature on MEMS thermal (calorimetric, time of flight, hot-film/hot-film) flow sensors published during the last two decades, we establish that for curtailing conductive heat losses in the sensors, researchers have either used low thermal conductivity substrate materials or, as a more effective solution, created low thermal conductivity membranes under the heaters/hot-films. However, no systematic experimental study exists that investigates the effect of membrane shape, membrane size, heater/hot-film length and M e m b r a n e (size) to H e a t e r (hot-film length) Ratio (MHR) on sensors’ conductive heat losses. Therefore, in this paper we have provided experimental evidence of dependence of conductive heat losses in membrane based MEMS hot-film flow sensors on MHR by using eight MEMS hot-film flow sensors, fabricated in a 1 µm silicon-on-insulator (SOI) CMOS foundry, that are thermally isolated by square and circular membranes. Experimental results demonstrate that: (a) thermal resistance of both square and circular membrane hot-film sensors increases with increasing MHR, and (b) conduction losses in square membrane based hot-film flow sensors are lower than the sensors having circular membrane. The difference (or gain) in thermal resistance of square membrane hot-film flow sensors viz-a-viz the sensors on circular membrane, however, decreases with increasing MHR. At MHR = 2, this difference is 5.2%, which reduces to 3.0% and 2.6% at MHR = 3 and MHR = 4, respectively. The study establishes that for membrane based SOI CMOS MEMS hot-film sensors, the optimum MHR is 3.35 for square membranes and 3.30 for circular membranes, beyond which the gain in sensors’ thermal efficiency (thermal resistance) is not economical due to the associated sharp increase in the sensors’ (membrane) size, which makes sensors more expensive as well as fragile. This paper hence, provides a key guideline to MEMS researchers for designing the square and circular membranes-supported micro-machined thermal (hot-film) flow sensors that are thermally most-efficient, mechanically robust and economically viable.

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A maskless etching technique for fabrication of 3D MEMS structures in SOI CMOS devices

Mansoor¹,

Haneef²,

Luca³

et al. 2018

J. Micromech. Microeng.

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A maskless etching technique for fabrication of 3D MEMS structures has been presented. The technique has been applied to micro structures embedded during a CMOS process in the dielectric membrane, which was realized by post-CMOS DRIE (deep reactive ion etching) back etch step. A comparison of the conventional etching technique with the developed maskless technique has been presented. The proposed technique takes advantage of the UV (ultra violet) transparent dielectric membrane supporting the CMOS-process based micro structures, where the UV light exposure of the photoresist on the top surface of the device is carried out from the reverse side through the UV-transparent membrane. The surrounding excess membrane is then etched away using suitable anisotropic etching technique such as RIE (reactive ion etching) to release 3D active structures in the CMOS MEMS device. The technique eliminates the requirement of a dedicated photo-mask as the CMOS metallization layer based micro structures are used to transfer the exact pattern on the device surface. Furthermore, expensive mask alignment equipment and skilled human resource is also not required. Thus the reported technique results in overall process simplification, fabrication process time and cost reduction and device yield enhancement. The proposed technique has also been successfully demonstrated to fabricate CMOS MEMS thermal wall shear stress sensors with significantly lower power consumption and stable performance.

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A thermopile based SOI CMOS MEMS wall shear stress sensor

Cited by 7 publications

References 16 publications

High-Sensitivity Single Thermopile SOI CMOS MEMS Thermal Wall Shear Stress Sensor

High-Sensitivity Single Thermopile SOI CMOS MEMS Thermal Wall Shear Stress Sensor

Sensitivity Enhancement of Silicon-on-Insulator CMOS MEMS Thermal Hot-Film Flow Sensors by Minimizing Membrane Conductive Heat Losses

A maskless etching technique for fabrication of 3D MEMS structures in SOI CMOS devices

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