Geometric optimization of van der Pauw structure based MEMS pressure sensor

Mian, Ahsan; Law, Jesse

doi:10.1007/s00542-010-1124-7

Cited by 7 publications

(6 citation statements)

References 6 publications

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“…The angular dependence on the NRCD has been found previously reported in Mian and Law (2010b). The diaphragms on the wafers which were designed to measure angular misalignment each contain four VDPs at 1°and 3°CW and CCW.…”

Section: Vdp Sensitivity Versus Rotational Misalignmentmentioning

confidence: 88%

“…The diaphragms on the wafers which were designed to measure angular misalignment each contain four VDPs at 1°and 3°CW and CCW. Once again, because the piezoresistive coefficients are unknown for the fabricated devices, and because slight differences exist between the FEA model used by Mian and Law (2010b) and the fabricated devices, this discussion will also be limited to qualitative analysis. The results for angular dependence for both the fabricated devices, and the FEA models are shown in Fig.…”

Section: Vdp Sensitivity Versus Rotational Misalignmentmentioning

confidence: 99%

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Design, fabrication, and testing of VDP MEMS pressure sensors

2011

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In this paper, a four-terminal piezoresistive sensor commonly known as a van der Pauw (VDP) structure is presented for its application to MEMS pressure sensing. In a recent study, our team has determined the relation between the biaxial stress state and the piezoresistive response of a VDP structure by combining the VDP resistance equations with the equations governing silicon piezoresistivity and has proposed a new piezoresistive pressure sensor. It was observed that the sensitivity of the VDP sensor is over three times higher than the conventional filament type Wheatstone bridge resistor. To check our theoretical findings, we fabricated several (100) silicon diaphragms with both the VDP sensors and filament resistor sensors on the same wafer so both the sensor elements have same doping concentration. Several diaphragms had VDP sensors of different sizes and orientations to find out their geometric effects on pressure sensitivity. The diaphragms were subjected to known pressures, and the pressure sensitivities of both types of sensors were measured using an in-house built calibration setup. It was found that the VDP devices had a linear response to pressure as expected, and were more sensitive than the resistor sensors. Also, the VDP sensors provided a number of additional advantages, such as its size independent sensitivity and simple fabrication steps due to its simple geometry.

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Section: Vdp Sensitivity Versus Rotational Misalignmentmentioning

confidence: 88%

Section: Vdp Sensitivity Versus Rotational Misalignmentmentioning

confidence: 99%

Design, fabrication, and testing of VDP MEMS pressure sensors

2011

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“…The current is usually supplied at terminals (pads) A and B, and voltage is measured at terminals (pads) C and D. Finally, the resistance ( ) or change in resistance (Δ ) is calculated from CD / AB . It was shown in [9,10] that the normalized resistance change requires two separate measurements with current supplied individually at adjacent sides. Jaeger et al [9] presented numerical and experimental results for four-wire bridge-mode operation (Figure 1(b)) that eliminates two separate resistance measurements required for a traditional square VDP sensor.…”

Section: Introductionmentioning

confidence: 99%

Four-Terminal Square Piezoresistive Sensors for MEMS Pressure Sensing

Hossain

Mian

2017

Journal of Sensors

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The sensitivity of four-terminal piezoresistive sensors commonly referred to as van der Pauw (VDP) structure is investigated. The VDP sensor is considered to be fabricated on (100) silicon due to its potential application in MEMS (microelectromechanical systems) pressure sensors. The sensitivity of the VDP sensor may be affected by misalignment during the etching/diffusion process, the nonuniformity of piezoresistive coefficients through the sensor thickness, and pad size with respect to the sensor size. For this particular analysis, the effect of VDP stress sensitivity on variations in pad sizes and through-the-thickness π-coefficient variation are studied as the effect of misalignment has already been investigated by researchers. Two three-dimensional (3D) finite element analysis (FEA) models are first developed for both traditional VDP resistance and equivalent four-wire bridge measurements. Then, the FEA models are validated with the closed form analytical solutions for point contacts (“zero” pad size) under different biaxial loads. Once the FEA models are validated, additional simulations are conducted to understand the influence of different parameters on the voltage measurements for an equivalent four-wire bridge configuration. It is observed that pad size and through-the-thickness nonuniformity in piezoresistive constants adversely affect the sensor sensitivity.

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“…In addition to the small device size this involves other important advantages such as light weight, minimum power consumption, low cost, better sensitivity and high resolution. This technology was successfully employed for the realization of portable devices such as gyroscopes (Chang et al, 2008), accelerometers (Li et al, 2011), micromirrors (Singh et al, 2008), and pressure sensors (Mian & Law, 2010).…”

Section: Introductionmentioning

confidence: 99%