Implementation of a gap-closing differential capacitive sensing<i>Z</i>-axis accelerometer on an SOI wafer

Hsu, Chia-Pao; Yip, Ming‐Chuen; Fang, Weileun

doi:10.1088/0960-1317/19/7/075006

Cited by 36 publications

(14 citation statements)

References 16 publications

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“…Hsu [13] Gap-closing differential capacitive 3.05 kHz Not given 0.2 V/g 2% (1 g) Yazdi [16] Sandwich structure with all-silicon single-wafer 885 Hz 16.7 2.2 pF/g Not given Hu [14] Sandwich structure with glass-Si-glass 742 Hz Not given 1.096 V/g 0.356% (1 g) Xiao [6] Sandwich structure with all silicon bonding 696 Hz 47 0.35 V/g Not given Zhou [15] 812 Hz 18 1.39 V/g 0.49% (1 g) This work 2.24 kHz 106 0.24 V/g 0.29% (1 g) …”

Section: Structurementioning

confidence: 99%

“…Fabricating beam-mass structure on the SOI substrate presents many excellent virtues like simple fabrication process and feasibility of fabrication of thick device. Thus the SOI based capacitive accelerometers are ardently designed and fabricated in recent years [11][12][13]. Nevertheless, to achieve the Z-axis acceleration detection, the design of symmetrical structure on SOI wafers is still in study.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Design and fabrication of a MEMS capacitive accelerometer with fully symmetrical double-sided H-shaped beam structure

Zhou

Che

Liang

et al. 2015

Microelectronic Engineering

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Section: Structurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Design and fabrication of a MEMS capacitive accelerometer with fully symmetrical double-sided H-shaped beam structure

Zhou

Che

Liang

et al. 2015

Microelectronic Engineering

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“…The desired properties of microaccelerometers include high sensitivity, maximum operating range, wide frequency response, high resolution, good linearity, low offset, shock survival ability and low cross-axis sensitivity. There are several mechanisms for acceleration sensing such as piezoresistive (Roylance and Angell 1979;Allen et al 1989;Tschan et al 1991;Riethmuller et al 1992;Burrer et al 1994;Kim et al 1995;Chen et al 1997;Takao and Matsumoto 1998;Plaza et al 1998;Kwon and Park 1998;Patridge et al 2000;Huang et al 2005;Park et al 2006;Amarasinghe et al 2005;Kal et al 2006;Eklund and Shkel 2007;Dong et al 2008;Engesser et al 2009;Ravi Sankar et al 2009a, b), piezoelectric (Kobayashi et al 2010), capacitive (Hsu et al 2009;Farahani et al 2009;Ravi Sankar et al 2011), tunneling (Hsien et al 1998), etc. Each of the above acceleration sensing mechanisms has its own merits and demerits.…”

Section: Introductionmentioning

confidence: 99%

Design, fabrication and testing of a high performance silicon piezoresistive Z-axis accelerometer with proof mass-edge-aligned-flexures

2011

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This paper presents design, fabrication and testing of a quad beam silicon piezoresistive Z-axis accelerometer with very low cross-axis sensitivity. The accelerometer device proposed in the present work consists of a thick proof mass supported by four thin beams (also called as flexures) that are connected to an outer supporting rim. Cross-axis sensitivity in piezoresistive accelerometers is an important issue particularly for high performance applications. In the present study, low cross-axis sensitivity is achieved by improving the device stability by placing the four flexures in line with the proof mass edges. Various modules of a finite element method based software called CoventorWare TM was used for design optimization. Based on the simulation results, a flexure thickness of 30 lm and a diffused resistor doping concentration of 5 9 10 18 atoms/cm 3 were fixed to achieve a high prime-axis sensitivity of 122 lV/Vg, low cross-axis sensitivity of 27 ppm and a relatively higher bandwidth of 2.89 kHz. The designed accelerometer was realized by a complementary metal oxide semiconductor compatible bulk micromachining process using a dual doped tetra methyl ammonium hydroxide etching solution. The fabricated accelerometer devices were tested up to 13 g static acceleration using a rate table. Test results of fabricated devices with 30 lm flexure thickness show an average prime axis sensitivity of 111 lV/Vg with very low cross-axis sensitivities of 0.652 and 0.688 lV/Vg along X-axis and Y-axis, respectively.

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“…High-aspect-ratio structures are preferred in micro sensors and actuators for better performance, so microelectromechanical systems (MEMS) devices based on bulk micromachining, especially on silicon-on-insulator (SOI) wafers, have been widely developed, such as resonators (Xu and Tsai 2012), optical mirrors (Mu et al 2013), accelerometers (Hsu et al 2009;Xie et al 2011) and gyroscopes (Trusov et al 2011;Zaman et al 2008) used trench technology to improve fabrication process of actuators consisting of a large number of elastic electrodes to develop low volume, large force and nanometer resolution electrostatic actuator for low displacement applications. Chang et al (2004) found that low stress TEOS/ ozone by the sub-atmospheric chemical vapor deposition (SACVD) process has excellent conformal step coverage at low temperature.…”

Section: Introductionmentioning

confidence: 99%

Fabrication challenges and test structures for high-aspect-ratio SOI MEMS devices with refilled electrical isolation trenches

Xie

2014

Microsyst Technol

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advantages such as superior material properties of a single crystal material, easily achieved high-aspect-ratio microstructures, large proof mass, good mechanical stability, less residual stress and simple fabrication process. In the fabrication, device layer of SOI wafer is etched to buried oxide to form mechanical elements and electrodes. The elements with the same potential could be electrically connected by wire bonding, but if a large number of elements are to be connected, wire bonding becomes an impractical means. Meanwhile, MEMS devices such as accelerometers and gyroscopes may have better performance when monolithically integrating high-aspect-ratio structures and interface circuits in the same substrate. To realize such configuration, metal interconnections are required to cross the trenches to electrically connect mechanical elements and circuits. Therefore, the deep trenches need to be refilled with insulating materials so that the refilled trenches can electrically isolate the mechanical elements from each other while maintaining robust mechanical connection. In addition, with the interconnections across the refilled trenches, the number of wire bonds can be greatly reduced, and thus parasitic capacitance and contact resistance is minimized.There have been many efforts to develop bulk micromachining or SOI sensors and actuators with refilled isolation trenches. The earliest work about refilled isolation trench in MEMS devices was reported in 1997 (Brosnihan et al. 1997), which describes a technique for providing both electrical isolation and embedded interconnect to SOI-based inertial sensors, and realizes high-aspect-ratio in-plane capacitive sensors with improved sensitivity suitable for integration with on-chip electronics. Schenk et al. (2000) presented an electrostatically driven silicon micro scanning mirror with electrical isolation trenches design, which allows different potentials between driving electrodes and the mirror plate.Abstract Refilled electrical isolation trenches are created for monolithic integration of high-aspect-ratio MEMS devices and circuitry in the same substrate. The refilled trenches electrically isolate the mechanical elements from each other while maintaining robust mechanical connection. It is found that silicon residue at the terminal of trench and metal stringers along indentation on trench surface are the two main fabrication issues, which often cause short circuit problem for MEMS devices with refilled isolation trenches. In this paper, fabrication challenges and solutions are presented for practical implementation of refilled electrical isolation trenches for high-aspect-ratio SOI MEMS devices. Test structures are designed to inline validate reliability of key steps in the process. Finally, an in-plane capacitive accelerometer is successfully fabricated on 50 μm SOI wafer with the improved fabrication process.

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Implementation of a gap-closing differential capacitive sensingZ-axis accelerometer on an SOI wafer

Cited by 36 publications

References 16 publications

Design and fabrication of a MEMS capacitive accelerometer with fully symmetrical double-sided H-shaped beam structure

Design and fabrication of a MEMS capacitive accelerometer with fully symmetrical double-sided H-shaped beam structure

Design, fabrication and testing of a high performance silicon piezoresistive Z-axis accelerometer with proof mass-edge-aligned-flexures

Fabrication challenges and test structures for high-aspect-ratio SOI MEMS devices with refilled electrical isolation trenches

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