Modeling and Simulation of Polysilicon Piezoresistors in a CMOS-MEMS Resonator for Mass Detection (original) (raw)
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This research studies longitudinal and transverse polysilicon resistors deposited in the maximum stress points of a CMOS-MEMS resonator for mass detection. The longitudinally mounted resistors were found to increase with the stress and giving maximum of resistance change of 10 to 23 when the actuation voltage was varied from 50 to 180 V, while the transverse resistors were found to decrease from 0.8 to 0.4 for the given voltages. Possible Wheatstone bridge configurations were studied to get the maximum output voltage, which was found to be 14 mV when two equal longitudinal resistors are connected with two equal external resistors to form a half bridge configuration.
2015 6th International Conference on Intelligent Systems, Modelling and Simulation, 2015
This research studies longitudinal and transverse polysilicon resistors deposited in the maximum stress points of a CMOS-MEMS resonator for mass detection. The longitudinally mounted resistors were found to increase with the stress and giving maximum of resistance change of 10 to 23 when the actuation voltage was varied from 50 to 180 V, while the transverse resistors were found to decrease from 0.8 to 0.4 for the given voltages. Possible Wheatstone bridge configurations were studied to get the maximum output voltage, which was found to be 14 mV when two equal longitudinal resistors are connected with two equal external resistors to form a half bridge configuration.
Design, fabrication and characterization of a piezoelectric MEMS diaphragm resonator mass sensor
Journal of Micromechanics and Microengineering, 2013
We report in this paper the design, fabrication and experimental characterization of a piezoelectric MEMS microgenerator. This device scavenges the energy of ambient mechanical vibrations characterized by frequencies in the range of 1 kHz. This component is made with Aluminum Nitride thin film deposited with a CMOS compatible process. Moreover we analyze two possible solutions for the signal rectification: a discrete doubler-rectifier and a full custom power management circuit. The ASIC developed for this application takes advantage of diodes with very low threshold voltage and therefore allows the conversion of extremely low input voltages corresponding to very weak input accelerations. The volume of the proposed generator is inferior to 1mm 3 and the generated powers are in the range of 1µW. This system is intended to supply power to autonomous wireless sensor nodes.
This paper describes a one-port mechanical resonance detection scheme utilized on a piezoelectric thin film driven silicon circular diaphragm resonator and discusses the limitations to such an approach in degenerate mode mass detection sensors. The sensor utilizes degenerated vibration modes of a radial symmetrical microstructure thereby providing both a sense and reference mode allowing for minimization of environmental effects on performance. The circular diaphragm resonator was fabricated with thickness of 4.5 µm and diameter of 140 µm. A PZT thin film of 0.75 µm was patterned on the top surface for the purposes of excitation and vibration sensing. The device showed a resonant frequency of 5.8 MHz for the (1, 1) mode. An electronic interface circuit was designed to cancel out the large static and parasitic capacitance allowing for electrical detection of the mechanical vibration thereby enabling the frequency split between the sense and reference mode to be measured accurately. The extracted motional current, proportional to the vibration velocity, was fed back to the drive to effectively increase the Q factor, and therefore device sensitivity, by more than a factor of 8. A software phase-locked loop was implemented to automatically track the resonant frequencies to allow for faster and accurate resonance detection. Results showed that by utilizing the absolute mode frequencies as an indication of sensor temperature, the variation in sensor temperature due to the heating from the drive electronics was accounted for and led to an ultimate measurement sensitivity of 2.3 Hz.
Technique and Circuit for Contactless Readout of Piezoelectric MEMS Resonator Sensors
Sensors, 2020
A technique and electronic circuit for contactless electromagnetic interrogation of piezoelectric micro-electromechanical system (MEMS) resonator sensors are proposed. The adopted resonator is an aluminum-nitride (AlN) thin-film piezoelectric-on-silicon (TPoS) disk vibrating in radial contour mode at about 6.3 MHz. The MEMS resonator is operated in one-port configuration and it is connected to a spiral coil, forming the sensor unit. A proximate electronic interrogation unit is electromagnetically coupled through a readout coil to the sensor unit. The proposed technique exploits interleaved excitation and detection phases of the MEMS resonator. A tailored electronic circuit manages the periodic switching between the excitation phase, where it generates the excitation signal driving the readout coil, and the detection phase, where it senses the transient decaying response of the resonator by measuring through a high-impedance amplifier the voltage induced back across the readout coil....
An A/D interface for resonant piezoresistive MEMS sensor
2004 IEEE International Symposium on Industrial Electronics, 2004
This paper introduces a original architecture to measure and convert into digital data the oscillations of a resonant beam. An electromechanical CMOS magnetic field sensor is considered here for the purpose of a case study. The proposed architecture is based on the counting of periods at an oscillator output, which frequency depends on the deformation of the mechanical structure. In order to cancel drifts, the architecture implements a differential measure by counting both up and down within a mechanical vibration period, using the actuation signal for synchronization. Simulation results demonstrate that high resolution can be achieved with acceptable integration time. Such a signal processing architecture is particularly suitable for low-cost CMOS mechanical structures.
Design and Analysis of MEMS-Based Piezoresistive Accelerometer with Low Cross-Axis Sensitivity
IOSR Journal of Engineering, 2013
This paper presents a design and development of a high-performance silicon piezoresistive MEMS accelerometer, with a finite element analysis (FEA) and low cross-axis sensitivity. Finite element analysis is used to simulate electro statically actuated piezoresistive accelerometer operating under dc conditions .The designs presented in this paper consist of a square shaped proof mass with flexures supporting it. Due to of the opposite nature of stress at two ends, these piezoresistors can be connected to form a Wheatstone bridge so that the cross-axis responses are practically reduced .The piezoresistors are placed near the proof mass and frame ends on the flexure. The simulations show the von Misses stress, displacement, Eigen frequency plot, voltage distribution and temperature change in the piezoresistors using COMSOL 4.3 Multiphysics.
Sensitivity Analysis of MEMS Based Piezoresistive Sensor Using COMSOL Multiphysics
Advances in Intelligent Systems and Computing, 2015
The present paper peruses MEMS based piezoresistive pressure sensor and its fabrication techniques. Simulation of the pressure sensor is done by using COMSOL Multiphysics software for P-type silicon piezoresistor. The deflection of N-type silicon diaphragm depends upon the Young's modulus of the material and varies with the amount of force applied to the diaphragm. The simulation result emphasizes that an appropriate selection of the piezoresistive material and the amount of force applied on the diaphragm impacts the sensor sensitivity levels upon low power consumption.
A critical review on design of MEMS based piezoresistive pressure sensor
One of the first MEMS devices to be commercialized is Piezoresistive pressure sensors. Piezoresistive pressure sensors are simpler to integrate with electronics, they are inherently shielded from RF noise and their response is more linear while compared to capacitive pressure sensors. Whereas, piezoresistive devices have always dominated the pressure sensor market. A silicon dioxide layer for isolation of piezoresistors from bulk is used in a Polysilicon based pressure sensors. Thereby reducing the leakage current compared to the p-n junction isolation in Si piezoresistors. This paper focuses on the review of piezoresistive pressure sensor principles, design, modeling, parameters to consider, materials that can be used in fabrication. Few models of piezoresistive pressure sensors have been simulated and the results are presented.
Design and Deformation Analysis of Mems Based Piezoresistive Pressure Sensor
2015
The present work reports about the design and simulation analysis of MEMS based piezoresistive pressure sensor. The design includes diaphragm using n-silicon material and piezoresistor using p-silicon material those are integrated on to diaphragm. Specifically, the proposed design has been simulated to get maximum deformation of diaphragm for small input of pressure. The design has been simulated for different crystallographic forms of silicon for different inputs Using COMSOL Multiphysics v 4.3b., the study is extended and analyses has been done such that flexibility of measuring pressure for polysilicon material has best performance compared to single crystal silicon and interchanged p-type, n-type of single crystal silicon.