Single proof-mass tri-axial pendulum accelerometers operating in vacuum

Serrano, Diego; Jeong, Yaesuk; Keesara, V.; Sung, Wang-Kyung; Ayazi, Farrokh

doi:10.1109/memsys.2014.6765565

Cited by 10 publications

(13 citation statements)

References 8 publications

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“…A three-axis accelerometer specifically designed for an inertial measurement unit (IMU) was reported by D.E. Serrano et al [ 62 ]. In their design, a three-axis pendulum accelerometer is proposed to operate in vacuum.…”

Section: Development Of Monolithic Multi-axis Capacitive Accelerommentioning

confidence: 99%

“…In the case of single proof-mass accelerometers, Tsai et al [ 60 ] has maximum sensitivity per unit area while [ 62 ] has a minimum noise area product. The accelerometer of [ 61 ] uses a novel method to fabricate comb fingers in the thickness direction, which improves Z-axis sensitivity.…”

Section: Development Of Monolithic Multi-axis Capacitive Accelerommentioning

confidence: 99%

“…The accelerometer of [ 61 ] uses a novel method to fabricate comb fingers in the thickness direction, which improves Z-axis sensitivity. The vacuum packaging in the case of [ 62 ] has helped the device to achieve a minimum noise-area product. The main problem which is faced by most single-proof mass accelerometers is with respect to Z-axis sensing.…”

Section: Development Of Monolithic Multi-axis Capacitive Accelerommentioning

confidence: 99%

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Monolithic Multi Degree of Freedom (MDoF) Capacitive MEMS Accelerometers

2018

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With the continuous advancements in microelectromechanical systems (MEMS) fabrication technology, inertial sensors like accelerometers and gyroscopes can be designed and manufactured with smaller footprint and lower power consumption. In the literature, there are several reported accelerometer designs based on MEMS technology and utilizing various transductions like capacitive, piezoelectric, optical, thermal, among several others. In particular, capacitive accelerometers are the most popular and highly researched due to several advantages like high sensitivity, low noise, low temperature sensitivity, linearity, and small footprint. Accelerometers can be designed to sense acceleration in all the three directions (X, Y, and Z-axis). Single-axis accelerometers are the most common and are often integrated orthogonally and combined as multiple-degree-of-freedom (MDoF) packages for sensing acceleration in the three directions. This type of MDoF increases the overall device footprint and cost. It also causes calibration errors and may require expensive compensations. Another type of MDoF accelerometers is based on monolithic integration and is proving to be effective in solving the footprint and calibration problems. There are mainly two classes of such monolithic MDoF accelerometers, depending on the number of proof masses used. The first class uses multiple proof masses with the main advantage being zero calibration issues. The second class uses a single proof mass, which results in compact device with a reduced noise floor. The latter class, however, suffers from high cross-axis sensitivity. It also requires very innovative layout designs, owing to the complicated mechanical structures and electrical contact placement. The performance complications due to nonlinearity, post fabrication process, and readout electronics affects both classes of accelerometers. In order to effectively compare them, we have used metrics such as sensitivity per unit area and noise-area product. This paper is devoted to an in-depth review of monolithic multi-axis capacitive MEMS accelerometers, including a detailed analysis of recent advancements aimed at solving their problems such as size, noise floor, cross-axis sensitivity, and process aware modeling.

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Section: Development Of Monolithic Multi-axis Capacitive Accelerommentioning

confidence: 99%

Section: Development Of Monolithic Multi-axis Capacitive Accelerommentioning

confidence: 99%

Section: Development Of Monolithic Multi-axis Capacitive Accelerommentioning

confidence: 99%

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Monolithic Multi Degree of Freedom (MDoF) Capacitive MEMS Accelerometers

2018

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“…Figure 7 shows an SEM view of the fabricated SD-BAW gyroscope. Devices were fabricated using a modified version of the highaspect ratio poly-and single-crystal silicon (HARPSS™) process flow 7 , in combination with planar X/Y-axis gyroscopes 34 and triaxial accelerometers 35 as part of a 6-degree-of-freedom system. The process uses SOI wafers with a 40-μm-thick structural layer and a 2-μm-thick buried oxide.…”

Section: Shock and Vibration Rejectionmentioning

confidence: 99%

Substrate-decoupled, bulk-acoustic wave gyroscopes: Design and evaluation of next-generation environmentally robust devices

Serrano¹,

Zaman²,

Rahafrooz³

et al. 2016

Microsyst Nanoeng

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This paper reports on a new type of high-frequency mode-matched gyroscope with significantly reduced dependencies on environmental stimuli such as temperature, vibration, and shock. A novel stress-isolation system is used to effectively decouple an axis-symmetric bulk-acoustic wave (BAW) vibratory gyro from its substrate, minimizing the effect that external sources of error have on the offset and scale factor of the device. Substrate-decoupled (SD) BAW gyros with a resonance frequency of 4.3 MHz and Q values near 60 000 were implemented using the high aspect ratio poly and single-crystal silicon (HARPSS) process to achieve ultra-narrow capacitive gaps. Wafer-level packaged sensors were interfaced with a customized application-specific integrated circuit (ASIC) to achieve low variations in the offset across temperature (±26°s − 1 from − 40 to 85°C), supreme random-vibration immunity (0.012°s − 1 g RMS − 1 ) and excellent shock rejection. With a scale factor of 800 μV (°s, the SD-BAW gyro system attains a large full-scale range (±1250°s) with a non-linearity of less than 0.07%. A measured angle-random walk (ARW) of 0.39°/√h and a bias instability of 10.5°h − 1 are dominated by the thermal and flicker noise of the integrated circuit (IC), respectively. Additional measurements using external electronics show bias-instability values as low as 3.5°h INTRODUCTIONMicromachined gyroscopes have enabled a myriad of applications that range from basic motion detection for gaming to safety control systems in automobiles 1 . More recently, an increased interest in the use of microelectromechanical system inertial sensors for dead reckoning and pedestrian navigation in handheld electronics has placed stringent requirements on the die size, power consumption, and overall performance of this type of device. To date, most commercially available rate sensors have been designed as low-frequency flexural tuning-fork gyroscopes (TFGs), which are typically sensitive to random vibrations and prone to linear accelerations, such as those experienced under shock. These limitations complicate the use of TFG technology in large-volume, high-end applications, particularly in personal navigation, for which dependencies on fluctuations in the environment translate into long-term drift in the output of the system. Additionally, in recent months, concerns about the high sensitivity of consumer-grade gyroscopes in response to lowfrequency pressure signals that can be used to recover audio have increased as a potential threat for eavesdropping 2 , justifying the need for more environmentally robust rotation sensors.Acceleration suppression mechanisms can be implemented in TFGs to alleviate part of this problem using redundant proof masses that reject shock and vibration as common-mode signals 3 .

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“…MEMS gyroscopes are self-contained rotation sensors that can be integrated with linear accelerometers to make single-chip inertial measurement units (IMUs) [1][2][3] . Their small size and low cost have made them successful in various applications ranging from gaming to automotive safety control and have made them promising candidates for personal inertial navigation applications in GPS (global positioning system)-denied environments 1 .…”

Section: Introductionmentioning

confidence: 99%

Resonant pitch and roll silicon gyroscopes with sub-micron-gap slanted electrodes: Breaking the barrier toward high-performance monolithic inertial measurement units

2017

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This paper presents the design, fabrication, and characterization of a novel high quality factor (Q) resonant pitch/roll gyroscope implemented in a 40 μm (100) silicon-on-insulator (SOI) substrate without using the deep reactive-ion etching (DRIE) process. The featured silicon gyroscope has a mode-matched operating frequency of 200 kHz and is the first out-of-plane pitch/roll gyroscope with electrostatic quadrature tuning capability to fully compensate for fabrication non-idealities and variation in SOI thickness. The quadrature tuning is enabled by slanted electrodes with sub-micron capacitive gaps along the (111) plane created by an anisotropic wet etching. The quadrature cancellation enables a 20-fold improvement in the scale factor for a typical fabricated device. Noise measurement of quadrature-cancelled mode-matched devices shows an angle random walk (ARW) of 0.63°√h − 1 and a bias instability of 37.7°h − 1 , partially limited by the noise of the interface electronics. The elimination of silicon DRIE in the anisotropically wet-etched gyroscope improves the gyroscope robustness against the process variation and reduces the fabrication costs. The use of a slanted electrode for quadrature tuning demonstrates an effective path to reach high-performance in future pitch and roll gyroscope designs for the implementation of single-chip high-precision inertial measurement units (IMUs).

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Single proof-mass tri-axial pendulum accelerometers operating in vacuum

Cited by 10 publications

References 8 publications

Monolithic Multi Degree of Freedom (MDoF) Capacitive MEMS Accelerometers

Monolithic Multi Degree of Freedom (MDoF) Capacitive MEMS Accelerometers

Substrate-decoupled, bulk-acoustic wave gyroscopes: Design and evaluation of next-generation environmentally robust devices

Resonant pitch and roll silicon gyroscopes with sub-micron-gap slanted electrodes: Breaking the barrier toward high-performance monolithic inertial measurement units

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