Fabrication of a sandwich type three axis capacitive MEMS accelerometer

Tez, Serdar; Akın, Tayfun

doi:10.1109/icsens.2013.6688598

Cited by 11 publications

(6 citation statements)

References 7 publications

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“…A sandwich three-axis bulk-micromachined accelerometer with three individual proof masses is proposed by S. Tez and T. Akin [ 48 , 49 ]. The design consists of comb fingers proof masses for in-plane sensing and electrode plates (top and bottom) for Z-axis sensing.…”

Section: Development Of Monolithic Multi-axis Capacitive Accelerommentioning

confidence: 99%

“…The overall die size is 12 mm × 7 mm × 1 mm and the structural thickness of the device is 35 μm. The main focus of [ 48 , 49 ] is to reduce the cross-axis sensitivity and achieve low noise in a reasonable measurement range. A Double-Glass, Modified Silicon-on-Glass (DGM-SOG) process is used for fabrication.…”

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%

Monolithic Multi Degree of Freedom (MDoF) Capacitive MEMS Accelerometers

2018

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“…Low-noise characteristics and low power consumption of the sensor interface circuits have become essential requirements. Capacitive microsensors are widely adopted in various applications such as humidity sensors, accelerometers, gyroscopes, biological sensors, pressure sensors, touch screen sensors, and proximity sensors [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. With the wide use of capacitive microsensors, many research works on capacitive microsensor interface circuit techniques have been reported [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ].…”

Section: Introductionmentioning

confidence: 99%

Reconfigurable Sensor Analog Front-End Using Low-Noise Chopper-Stabilized Delta-Sigma Capacitance-to-Digital Converter

et al. 2018

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This paper proposes a reconfigurable sensor analog front-end using low-noise chopper-stabilized delta-sigma capacitance-to-digital converter (CDC) for capacitive microsensors. The proposed reconfigurable sensor analog front-end can drive both capacitive microsensors and voltage signals by direct conversion without a front-end amplifier. The reconfigurable scheme of the front-end can be implemented in various multi-mode applications, where it is equipped with a fully integrated temperature sensor. A chopper stabilization technique is implemented here to achieve a low-noise characteristic by reducing unexpected low-frequency noises such as offsets and flicker noise. The prototype chip of the proposed sensor analog front-end is fabricated by a standard 0.18-μm 1-poly-6-metal (1P6M) complementary metal-oxide-semiconductor (CMOS) process. It occupies a total active area of 5.37 mm2 and achieves an effective resolution of 16.3-bit. The total power consumption is 0.843 mW with a 1.8 V power supply.

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“…Compared with other bonding technologies, Au/Si eutectic bonding benefits from a low eutectic temperature (363 °C), being non-sensitive to the roughness of bonding surface and particles, having good mechanical stability, and compatibility with aluminum interconnect [ 4 ]. Therefore, it is considered the most important approach to establishing strong bonds and hermetic seals, and is widely used in the fabrication of MEMS devices, 3D interconnects, and wafer-level vacuum packaging [ 5 , 6 ]. As such, Au/Si eutectic bonding has been investigated extensively.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Au/Si Eutectic Wafer Bonding for MEMS Accelerometers

Shang

Yin

et al. 2017

Micromachines

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Au/Si eutectic bonding is considered to BE a promising technology for creating 3D structures and hermetic packaging in micro-electro-mechanical system (MEMS) devices. However, it suffers from the problems of a non-uniform bonding interface and complex processes for the interconnection of metal wires. This paper presents a novel Au/Si eutectic wafer bonding structure and an implementation method for MEMS accelerometer packaging. The related processing parameters influencing the Au/Si eutectic bonding quality were widely investigated. It was found that a high temperature of 400 °C with a low heating/cooling rate of 5 °C/min is crucial for successful Au/Si eutectic bonding. High contact force is beneficial for bonding uniformity, but the bonding strength and bonding yield decrease when the contact force increases from 3000 to 5000 N due to the metal squeezing out of the interface. The application of TiW as an adhesion layer on a glass substrate, compared with a commonly used Cr or Ti layer, significantly improves the bonding quality. The bonding strength is higher than 50 MPa, and the bonding yield is above 90% for the presented Au/Si eutectic bonding. Furthermore, the wafer-level vacuum packaging of the MEMS accelerometer was achieved based on Au/Si eutectic bonding and anodic bonding with one process. Testing results show a nonlinearity of 0.91% and a sensitivity of 1.06 V/g for the MEMS accelerometer. This Au/Si eutectic bonding process can be applied to the development of reliable, low-temperature, low-cost fabrication and hermetic packaging for MEMS devices.

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Fabrication of a sandwich type three axis capacitive MEMS accelerometer

Cited by 11 publications

References 7 publications

Monolithic Multi Degree of Freedom (MDoF) Capacitive MEMS Accelerometers

Monolithic Multi Degree of Freedom (MDoF) Capacitive MEMS Accelerometers

Reconfigurable Sensor Analog Front-End Using Low-Noise Chopper-Stabilized Delta-Sigma Capacitance-to-Digital Converter

Investigation of Au/Si Eutectic Wafer Bonding for MEMS Accelerometers

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