A novel sacrificial-layer process based on anodic bonding and its application in an accelerometer

Wang, Lingyun; He, Yong; Zhan, Zhan; Yu, Lian; Wang, Huan; Chen, Daner

doi:10.1063/1.4907930

Cited by 8 publications

(6 citation statements)

References 5 publications

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“…The content of Na increased at a distance of 0.7 µm, so the Na depletion zone can be considered to be 0.3 µm. According to Wang's [25] research, the width of the depletion layer was approximately proportional to the bonding temperature and bonding voltage. From figure 4, it can be seen that the Al and glass was bonded together very well, and there was a Na depletion zone in the glass.…”

Section: Gd-oes Testing Resultsmentioning

confidence: 99%

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Interfacial investigation and mechanical properties of glass-Al-glass anodic bonding process

Xue

Shi

2017

J. Micromech. Microeng.

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Glass-Al-glass with Al as common anode was successfully bonded together through the anodic bonding process. SEM and EDS were conducted to investigate the interfacial structure of the glass-Al-glass samples. Special attention was given to the element distribution after the bonding process. The element profile of the transitional layer was investigated by glow discharge optical emission microscopy. The results showed that ion migration played an important role during the anodic bonding process, Na + would precipitate from the back of the glass, and a Na + depletion region formed at the bonding interface. At the same time, O 2− diffused into the bonding interface and reacted with the Al, which resulted in a successful bonding process. Furthermore, Al migrated into the glass, which could enhance the bonding process. The peak current of the glass-Al-glass bonding was two times larger than that of the Al-glass bonding, which meant that the glass-Al-glass bonding process could be considered equivalent to two individual Al-glass bonding processes. Tensile strength tests showed that the glass was fractured, and the fractures propagated into the bonding interface, which indicated a reliable bonding process.

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Section: Gd-oes Testing Resultsmentioning

confidence: 99%

“…This finding provides useful information on bonding multiple-layer instruments and designing complicated devices, such as microvalves [2]. Also, glass-Si-glass can be bonded together by this technique, which can be used to fabricate capacitive accelerometers [25] and microscanners [26].…”

Section: Introductionmentioning

confidence: 86%

Interfacial investigation and mechanical properties of glass-Al-glass anodic bonding process

Xue

Shi

2017

J. Micromech. Microeng.

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“…Anodic bonding offers new ways to fabricate micro electro mechanical systems (MEMS) with excellent properties, such as satisfactorily high bonding strength, low temperature, simplicity, high-quality hermetic sealing and encapsulation [1] and so on. Until now, anodic bonding has been used widely in MEMS fabrication, such as shear stress sensor [2], accelerometer [3], ultrasonic transducers [4,5], magnetometer [6] and even some solar cells [7].…”

Section: Introductionmentioning

confidence: 99%

Study on the mechanism of Si–glass–Si two step anodic bonding process

Wang

Xue

et al. 2018

J. Micromech. Microeng.

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Si–glass–Si was successfully bonded together through a two-step anodic bonding process. The bonding current in each step of the two-step bonding process was investigated, and found to be quite different. The first bonding current decreased quickly to a relatively small value, but for the second bonding step, there were two current peaks; the current first decreased, then increased, and then decreased again. The second current peak occurred earlier with higher temperature and voltage. The two-step anodic bonding process was investigated in terms of bonding current. SEM and EDS tests were conducted to investigate the interfacial structure of the Si–glass–Si samples. The two bonding interfaces were almost the same, but after an etching process, transitional layers could be found in the bonding interface and a deeper trench with a thickness of ~1.5 µm could be found in the second bonding interface. Atomic force microscopy mapping results indicated that sodium precipitated from the back of the glass, which makes the roughness of the surface become coarse. Tensile tests indicated that the fracture occurred at the glass substrate and that the bonding strength increased with the increment of bonding temperature and voltage with the maximum strength of 6.4 MPa.

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“…Wafer bonding is as a key technology for microelectronics and micro-electro-mechanical systems (MEMS) for creating three-dimensional (3D) structures and hermetic packaging. Several bonding techniques have been developed in the last several decades, including silicon fusion bonding, anodic bonding, solder bonding, adhesive bonding, and eutectic bonding [ 1 , 2 , 3 ]. 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 ].…”

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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A novel sacrificial-layer process based on anodic bonding and its application in an accelerometer

Cited by 8 publications

References 5 publications

Interfacial investigation and mechanical properties of glass-Al-glass anodic bonding process

Interfacial investigation and mechanical properties of glass-Al-glass anodic bonding process

Study on the mechanism of Si–glass–Si two step anodic bonding process

Investigation of Au/Si Eutectic Wafer Bonding for MEMS Accelerometers

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