High Performance MEMS Research Articles

Micro-Electro-Mechanical Systems Microphones: A Brief Review Emphasizing Recent Advances in Audible Spectrum Applications.

The MEMS microphone is a representative device among the MEMS family, which has attracted substantial research interest, and those tailored for human voice have earned distinct success in commercialization. Although sustained development persists, challenges such as residual stress, environmental noise, and structural innovation are posed. To collect and summarize the recent advances in this subject, this paper presents a concise review concerning the transduction mechanism, diverse mechanical structure topologies, and effective methods of noise reduction for high-performance MEMS microphones with a dynamic range akin to the audible spectrum, aiming to provide a comprehensive and adequate analysis of this scope.

Topology optimization research and simulation analysis of high-performance MEMS pressure sensor

Topology optimization research and simulation analysis of high-performance MEMS pressure sensor

A self-centering and stiffness-controlled MEMS accelerometer

This paper presents a high-performance MEMS accelerometer with a DC/AC electrostatic stiffness tuning capability based on double-sided parallel plates (DSPPs). DC and AC electrostatic tuning enable the adjustment of the effective stiffness and the calibration of the geometric offset of the proof mass, respectively. A dynamical model of the proposed accelerometer was developed considering both DC/AC electrostatic tuning and the temperature effect. Based on the dynamical model, a self-centering closed loop is proposed for pulling the reference position of the force-to-rebalance (FTR) to the geometric center of DSPP. The self-centering accelerometer operates at the optimal reference position by eliminating the temperature drift of the readout circuit and nulling the net electrostatic tuning forces. The stiffness closed-loop is also incorporated to prevent the pull-in instability of the tuned low-stiffness accelerometer under a dramatic temperature variation. Real-time adjustments of the reference position and the DC tuning voltage are utilized to compensate for the residue temperature drift of the proposed accelerometer. As a result, a novel controlling approach composed of a self-centering closed loop, stiffness-closed loop, and temperature drift compensation is achieved for the accelerometer, realizing a temperature drift coefficient (TDC) of approximately 7 μg/°C and an Allan bias instability of less than 1 μg.

Review of: "Molecular building blocks (proteins and nucleic acids, lipids and carbohydrates, DNA and RNA) can be used as an inspiring strategy on how to design high-performance NEMS and MEMS"

Review of: "Molecular building blocks (proteins and nucleic acids, lipids and carbohydrates, DNA and RNA) can be used as an inspiring strategy on how to design high-performance NEMS and MEMS"

Review of: "Molecular building blocks (proteins and nucleic acids, lipids and carbohydrates, DNA and RNA) can be used as an inspiring strategy for how to design high-performance NEMS and MEMS that have the required properties and characteristics."

Review of: "Molecular building blocks (proteins and nucleic acids, lipids and carbohydrates, DNA and RNA) can be used as an inspiring strategy for how to design high-performance NEMS and MEMS that have the required properties and characteristics."

A High-Performance RF MEMS Power Sensor for Near-Zero Detection Applications

A High-Performance RF MEMS Power Sensor for Near-Zero Detection Applications

Disclosing the annihilation effect of ion-implantation induced defects in single-crystal diamond by resonant MEMS

Single-crystal diamond presents as an ideal semiconductor material for high-performance and high-reliability MEMS devices, on account of its outstanding mechanical and physical properties. A smart-cut technology based on ion-implantation was proposed to fabricate the SCD-on-SCD MEMS resonators. However, the ion-implantation damage induced defects would degrade the quality (Q) factors of the diamond MEMS resonators. Here, we systematically investigate the effect of ultra-high vacuum annealing on the resonance properties of SCD cantilevers. It is observed that the Q factors are markedly improved by nearly twice after annealing at 1100 °C due to the annihilation of the ion implantation induced damage in the resonators. Therefore, reducing the defects in the resonators by high-temperature annealing the as-fabricated SCD MEMS cantilevers is one of the strategies to improve the Q factors. This work also proves out that MEMS represents a more sensitive tool for characterizing the crystalline quality of diamond, compared with the conventional structural methods.

A High-Performance Dual-Channel MEMS Microwave Power Sensor With Cantilever Beam

In order to optimize the sensitivity and overload power of microwave power sensor, a dual-channel MEMS microwave power sensor with cantilever beam is proposed in this paper. GaAs MMIC process and MEMS technology are used for design and manufacturing. The theoretical model of MEMS dual-channel microwave power sensor with cantilever beam is established. The influence of the size of the cantilever beam on the microwave performance, overload power and sensitivity of the sensor is studied. The microwave performance and sensitivity of three sensors with different cantilever beam sizes were tested. At 8-12 GHz, the return loss of three sensors are -10.6 dB~-57.2 dB@ 200 μm beam length, -10.6 dB~-62.4 dB@300 μm beam length, and -12.0 dB~-62.3 dB@400 μm beam length, respectively. They all show good microwave performance. At 10 GHz, the sensitivities of capacitive detection channel of three sensors are 16.3 fF/W, 65.6 fF/W and 144.4 fF/W respectively. And the sensitivities of thermoelectric detection channel are 142.3 mV/W, 109.5 mV/W and 82.9 mV/W respectively. The sensitivities of dual-channel MEMS microwave power sensors with cantilever beam are improved compared with the traditional microwave power sensor, which has certain reference value for the design of MEMS microwave power sensors.

High-Performance Two-Dimensional MEMS Micro-Magnetic Sensor With Magnetic Circuit Differential

Two-dimensional magnetic sensors of soft magnetic film/planar coil laminated have the advantages of low power consumption and high sensitivity, which has great potential in developing miniaturized high-performance magnetic sensors. However, the miniaturization of magnetic sensors increases the noise level resulting in limited detection ability. In this letter, a novel two-dimensional MEMS soft magnetic film/planar coil laminated micro-magnetic sensor with magnetic circuit differential is proposed. Magnetic circuit differential technology effectively reduces the common-mode noise of the micro-magnetic sensor, so the intrinsic noise of the proposed micro-magnetic sensor is significantly suppressed. Moreover, the geometric parameters of the proposed micro-magnetic sensor are optimized by MEMS technology, and the sensitivity is improved. Consequently, the detectivity of the two-dimensional MEMS micro-magnetic sensor with magnetic circuit differential is significantly enhanced. Experimental results show that the two-dimensional MEMS micro-magnetic sensor with magnetic circuit differential has a detection limit of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> Oe-level, which presents a good development prospect in the weak magnetic field.

A novel hardware implemented programmable controller adapted to cooperate with AI tuning algorithms in real time systems

A novel, transistor level PID (proportional–integrating–derivative) controller is proposed that may be easily coupled with various AI algorithms responsible for adjusting its main factors. In our work we focus on a discrete-time digital approach, as it facilities realization a flexible and programmable structure that can be quickly re-configured depending on varying environment conditions. One of the novelties of the proposed solution is its parallel and asynchronous structure that requires only simple 2-phases clock. Each of the P, I and D blocks is realized as a separate channel with its own multi-bit multiplier, a summing circuit and a short delay line (in case of I and D blocks). The circuit features small chip area. For the input signals, and the coefficients of the controller being encoded as 8-bit signals the number of transistors does not exceed 13,000, which translates into the chip area not exceeding 0.1 mm2 in the CMOS 130 nm technology. Data rate of the controller can achieve 200–330 MSamples/s, with power dissipation not exceeding 1 mW. The proposed solution is suitable for miniaturized microsystems, for example high performance MEMS devices, in which small sizes and high data rate become very important features.

Investigation and Research of High-Performance RF MEMS Switches for Use in the 5G RF Front-End Modules

In this article, based on the developed methodology, the stages of designing two designs of high-performance radio-frequency single-pole single-throw microelectromechanical switches are investigated. These radio-frequency microelectromechanical switches are designed to operate at a central resonant frequency of 3.6 GHz and 3.4 GHz, respectively, as well as to work both in mobile communication devices and in the design of the architecture of 5G mobile networks, in particular in arrays of integrated antennas and radio-frequency interface modules. The manufacture and study of two designed structures are researched. For the first manufactured experimental sample in the open state the insertion loss is no more than -0.69 dB and the reflection loss is -28.35 dB, and in the closed state the isolation value is at least -54.77 dB at a central resonant frequency of 3.6 GHz. For the second in the open state the value of the insertion loss is no more than -0.67 dB and the reflection loss is -20.7 dB, and in the closed state the isolation value is not less than -52.13 dB at the central resonant frequency of 3.4 GHz. Both manufactured experimental samples are characterized by high linearity, as well as a small value of contact resistance in the closed state.

Influence of structural orientation of tungsten oxide films on gas sensing properties

Tungsten oxide films with different preferred orientations were deposited by reactive magnetron sputtering with glancing angle deposition. The influence of the structural orientation of the films on the NO 2 gas sensing properties was investigated through orthogonal experiments. The film deposited at a lower Ar/O 2 ratio and higher sputtering pressure displayed a significantly enhanced NO 2 sensing performance, which can be attributed to the high crystallinity and (200)-preferred orientation of monoclinic WO 3 . There are more active sites near the surface of the (200)-oriented WO 3 films, which is beneficial for NO 2 adsorption, enhancing the gas sensing properties. Clarifying the effect of structural orientation on the gas response will guide further optimization of sensing films, aiding the fabrication of high-performance MEMS gas sensors. • WO 3 films with different degrees of preferred orientation were deposited by glancing angle deposition. • The WO 3 film with higher crystallinity and stronger (200)-preferred orientation displayed significantly enhanced response to NO 2 . • The improvement of sensing performance can be mainly attributed to more active sites for NO 2 adsorption near the surface of (200)-oriented monoclinic WO 3 . • The effect of structural orientation on gas response of WO 3 films can be used as a reference for further optimization of sensing films.

Bimorph Dual-Electrode ScAlN PMUT with Two Terminal Connections

This paper presents a novel bimorph Piezoelectric Micromachined Ultrasonic Transducer (PMUT) fabricated with 8-inch standard CMOS-compatible processes. The bimorph structure consists of two layers of 20% scandium-doped aluminum nitride (Sc0.2Al0.8N) thin films, which are sandwiched among three molybdenum (Mo) layers. All three Mo layers are segmented to form the outer ring and inner plate electrodes. Both top and bottom electrodes on the outer ring are electrically linked to the center inner plate electrodes. Likewise, the top and bottom center plate electrodes are electrically connected to the outer ring in the same fashion. This electrical configuration maximizes the effective area of the given PMUT design and improves efficiency during the electromechanical coupling process. In addition, the proposed bimorph structure further simplifies the device's electrical layout with only two-terminal connections as reported in many conventional unimorph PMUTs. The mechanical and acoustic measurements are conducted to verify the device's performance improvement. The dynamic mechanical displacement and acoustic output under a low driving voltage (1 Vpp) are more than twice that reported from conventional unimorph devices with a similar resonant frequency. Moreover, the pulse-echo experiments indicate an improved receiving voltage of 10 mV in comparison with the unimorph counterpart (4.8 mV). The validation of device advancement in the electromechanical coupling effect by using highly doped ScAlN thin film, the realization of the proposed bimorph PMUT on an 8-inch wafer paves the path to production of next generation, high-performance piezoelectric MEMS.

A review of high-performance MEMS sensors for resource exploration and geophysical applications

MEMS sensors have the advantages of small volume, lightweight, and low cost, therefore, have been widely used in the fields of consumer electronics, industry, health, defence, and aerospace. With their ever-improving performance, MEMS sensors have also started to be used in resource exploration and geophysical applications. However, the requirements of high-precision MEMS sensors for geophysical applications have not been specified in detail. Therefore, this paper systematically analyzes the requirements of high-performance MEMS sensors for prospecting and geophysical applications, including seismic surveillance, Earth tide, volcanic activity monitoring for natural disasters; seismic, gravity, and magnetic resource prospecting; drilling process monitoring and local gravity measurement for gravity aided navigation. Focusing on the above applications, this paper summarizes the state-of-the-art of research on high-performance MEMS sensors for resource exploration and geophysical applications. Several off-the-shelf MEMS sensors have been used for earthquake monitoring, seismic exploration and drilling process monitoring, and a range of MEMS research prototype sensors have successfully been employed for Earth tides measurement and are promising to be used for gravity exploration. MEMS magnetometers should have a lower noise floor to meet the demand for magnetic exploration. MEMS gravity gradiometers are still under early development and will not be deployable in short-term. High-performance MEMS sensors hold the advantages of low-cost, high integration, and capability of working in extreme environments; therefore, they are likely to gradually replace some conventional geophysical instruments in some application areas.

A High-Performance MEMS Accelerometer with an Improved TGV Process of Low Cost.

High-performance MEMS accelerometers usually use a pendulum structure with a larger mass. Although the performance of the device is guaranteed, the manufacturing cost is high. This paper proposes a method of fabricating high-performance MEMS accelerometers with a TGV process, which can reduce the manufacturing cost and ensure the low-noise characteristics of the device. The TGV processing relies on laser drilling, the metal filling in the hole is based on the casting mold and CMP, and the packaging adopts the three-layer anodic bonding process. Moreover, for the first time, the casting mold process is introduced to the preparation of MEMS devices. In terms of structural design, the stopper uses distributed comb electrodes for overload displacement suppression, and the gas released by the packaging method provides excellent mechanical damping characteristics. The prepared accelerometer has an anti-overload capability of 10,000 g, the noise density is less than 0.001°/√Hz, and it has ultra-high performance in tilt measurement.

Design, Modeling and Characterization of High-Performance Bulk-Mode Piezoelectric MEMS Resonators

In this paper, the design, modeling and characterization of width-extensional (WE) mode piezoelectric microelectromechanical systems (MEMS) resonators are presented. The resonators consist of piezoelectric stacked layers for transductions, highly doped single crystal silicon (HDS) device layer as vibrating structures, and oxide layers on top and bottom surfaces for passive temperature compensation. Dependencies of quality factors ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q\text{s}$ </tex-math></inline-formula> ) of the WE mode resonators on structure designs, such as device length, thickness as well as crystal orientation of the HDS device layer are investigated. Effects of crystal orientation of the HDS device layer and oxide thickness on the temperature stability of resonant frequency of the WE mode resonators are also analyzed. Both aluminum nitride (AlN) and scandium-doped aluminum nitride (Sc <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>x</i></sub> Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1−<i>x</i></sub> N, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$x=9.5\%$ </tex-math></inline-formula> ) are adopted as the piezoelectric transduction layer in this work, in order to investigate the performance improvements by Sc doping. The designed WE mode MEMS resonators are fabricated based on a piezoelectric on cavity-silicon-on-insulator (CSOI) platform. A fabricated ScAlN-based MEMS resonator exhibits a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula> of 11086 and motional impedance as low as 28 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> at its series resonant frequency of 25.044 MHz. [2021-0222]

Fully Integrated High-Performance MEMS Energy Harvester for Mechanical and Contactless Magnetic Excitation in Resonance and at Low Frequencies.

Energy harvesting and storage is highly demanded to enhance the lifetime of autonomous systems, such as IoT sensor nodes, avoiding costly and time-consuming battery replacement. However, cost efficient and small-scale energy harvesting systems with reasonable power output are still subjects of current development. In this work, we present a mechanically and magnetically excitable MEMS vibrational piezoelectric energy harvester featuring wafer-level integrated rare-earth micromagnets. The latter enable harvesting of energy efficiently both in resonance and from low-g, low-frequency mechanical energy sources. Under rotational magnetic excitation at frequencies below 50 Hz, RMS power output up to 74.11 µW is demonstrated in frequency up-conversion. Magnetic excitation in resonance results in open-circuit voltages > 9 V and RMS power output up to 139.39 µW. For purely mechanical excitation, the powder-based integration process allows the realization of high-density and thus compact proof masses in the cantilever design. Accordingly, the device achieves 24.75 µW power output under mechanical excitation of 0.75 g at resonance. The ability to load a capacitance of 2.8 µF at 2.5 V within 30 s is demonstrated, facilitating a custom design low-power ASIC.

Nonlinearity-mediated digitization and amplification in electromechanical phonon-cavity systems

Electromechanical phonon-cavity systems are man-made micro-structures, in which vibrational energy can be coherently transferred between different degrees of freedom. In such devices, the energy transfer direction and coupling strength can be parametrically controlled, offering great opportunities for both fundamental studies and practical applications such as phonon manipulation and sensing. However, to date the investigation of such systems has largely been limited to linear vibrations, while their responses in the nonlinear regime remain yet to be explored. Here, we demonstrate nonlinear operation of electromechanical phonon-cavity systems, and show that the resonant response differs drastically from that in the linear regime. We further demonstrate that by controlling the parametric pump, one can achieve nonlinearity-mediated digitization and amplification in the frequency domain, which can be exploited to build high-performance MEMS sensing devices based on phonon-cavity systems. Our findings offer intriguing opportunities for creating frequency-shift-based sensors and transducers.

High-performance inline RF MEMS switch for application in 5G mobile networks

This article presents the results of the design and analysis of a radio-frequency switch made using microelectromechanical systems technology. The device is the capacitive switch with a hybrid type of contact, in which the movable electrode of the structure – the metal membrane is part of the microwave signal line of the coplanar waveguide. The switch design is characterized by a high capacitance ratio and low contact resistance. The zig-zag elastic suspension is used to reduce the value of the pull-down voltage – 2 V and the switching time ∼ 7 us. The central resonant frequency of the switch is 3.8 GHz. In this case, in the open state, the value of the insertion loss is not more than -0.2 dB and the isolation value in the close state is not less than -55 dB. The effective frequency range is the S-band, as well as the C-, X- and Ku-band, in which the isolation value is at least -30 dB. The presented inline RF MEMS switch is suitable for use in various types of ground and satellite communications, in particular for devices and systems of 5G mobile networks.

Radially Pleated Disk Resonator for Gyroscopic Application

In this paper, we propose a radially pleated disk resonator for gyroscopic application. The structure is made up of concentrically nested radially pleated rings that are interconnected by straight spokes, which has the potential to provide higher thermo-elastic quality factor and larger vibration amplitude. Decaying time constant of 31 s is experimentally obtained at resonant frequency of 3 kHz. A frequency-tuning model is proposed and verified, based on which, the frequency-tuning characters of the radially pleated disk resonator are thoroughly investigated. The Coriolis coupling factor <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\kappa $ </tex-math></inline-formula> of the radially pleated disk resonator is precisely measured by constructing a concise quadrature frequency-modulation operation, which gives the values of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\kappa $ </tex-math></inline-formula> = 0.7687 and agrees well with the calculated value of 0.7768. This work provides a new strategy for designing high performance MEMS gyroscope structure, and gives a good template for gyroscopic resonator characterization. [2021-0096]