Low-temperature Al–Ge bonding for 3D integration

Crnogorac, F.; Pease, Fabian; Birringer, Ryan P.; Dauskardt, Reinhold H.

doi:10.1116/1.4762844

Cited by 8 publications

(8 citation statements)

References 31 publications

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“…This specific integration process is used for the manufacturing of very high-volume multi-axis gyroscope products distributed by InvenSense in the USA (manufactured by TSMC in Taiwan) 9,11,129 . In this process, the monocrystalline silicon MEMS sensors (e.g., gyroscopes), including the cap for the MEMS package, are prepared on an initial wafer that is subsequently bonded to a pre-fabricated CMOS-based IC wafer that contains etched cavities, as indicated in Figure 13a-c the combined gyro and cap wafer against the aluminium metal layer on the CMOS wafer 130 . Figure 13d shows SEM images of a gyroscope that was manufactured using this technology 9 .…”

Section: Heterogeneous Mems and Ic Integration With Via Formation Dur...mentioning

confidence: 99%

Integrating MEMS and ICs

et al. 2015

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The majority of microelectromechanical system (MEMS) devices must be combined with integrated circuits (ICs) for operation in larger electronic systems. While MEMS transducers sense or control physical, optical or chemical quantities, ICs typically provide functionalities related to the signals of these transducers, such as analog-to-digital conversion, amplification, filtering and information processing as well as communication between the MEMS transducer and the outside world. Thus, the vast majority of commercial MEMS products, such as accelerometers, gyroscopes and micro-mirror arrays, are integrated and packaged together with ICs. There are a variety of possible methods of integrating and packaging MEMS and IC components, and the technology of choice strongly depends on the device, the field of application and the commercial requirements. In this review paper, traditional as well as innovative and emerging approaches to MEMS and IC integration are reviewed. These include approaches based on the hybrid integration of multiple chips (multi-chip solutions) as well as system-on-chip solutions based on wafer-level monolithic integration and heterogeneous integration techniques. These are important technological building blocks for the 'More-ThanMoore' paradigm described in the International Technology Roadmap for Semiconductors. In this paper, the various approaches are categorized in a coherent manner, their merits are discussed, and suitable application areas and implementations are critically investigated. The implications of the different MEMS and IC integration approaches for packaging, testing and final system costs are reviewed.

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Section: Heterogeneous Mems and Ic Integration With Via Formation Dur...mentioning

confidence: 99%

Integrating MEMS and ICs

et al. 2015

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“…The proximity of the bonding temperature to CMOS thermal limits is a primary disadvantage of this approach. Solid-state bonding below the eutectic temperature has been shown to reduce bonding temperatures but at the expense of significant increases in bonding time and force [84]. …”

Section: Bonding Approachesmentioning

confidence: 99%

Wafer-Level Vacuum Packaging of Smart Sensors

Hilton

Temple

2016

Sensors

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The reach and impact of the Internet of Things will depend on the availability of low-cost, smart sensors—“low cost” for ubiquitous presence, and “smart” for connectivity and autonomy. By using wafer-level processes not only for the smart sensor fabrication and integration, but also for packaging, we can further greatly reduce the cost of sensor components and systems as well as further decrease their size and weight. This paper reviews the state-of-the-art in the wafer-level vacuum packaging technology of smart sensors. We describe the processes needed to create the wafer-scale vacuum microchambers, focusing on approaches that involve metal seals and that are compatible with the thermal budget of complementary metal-oxide semiconductor (CMOS) integrated circuits. We review choices of seal materials and structures that are available to a device designer, and present techniques used for the fabrication of metal seals on device and window wafers. We also analyze the deposition and activation of thin film getters needed to maintain vacuum in the ultra-small chambers, and the wafer-to-wafer bonding processes that form the hermetic seal. We discuss inherent trade-offs and challenges of each seal material set and the corresponding bonding processes. Finally, we identify areas for further research that could help broaden implementations of the wafer-level vacuum packaging technology.

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“…Most Ru contact studies test unpackaged devices [10], [11], [12]. MEMS device bonding with Al-Ge [13], [14], [15], Au-Sn [16], [17], In-Ga [18] polymer adhesive [7], glass frit and anodic bonding has been reported, but to the best of our knowledge there is a research gap with regard to Ru compatibility with a bonding process. This paper explores the compatibility of Ru in contact with Al-Ge eutectic alloy in the context of a MEMS WLP process.…”

Section: Introductionmentioning

confidence: 99%

“…Concerns about Ru compatibility with Al-Ge bonding are primarily inspired by the case of Si and the need for Si diffusion barriers reported in literature [13], [14], [15]. Si diffusion can introduce melt failure in Al-Ge by the creation of an Al-Ge-Si ternary alloy with an elevated melting temperature.…”

Section: Introductionmentioning

confidence: 99%

“…Bonding at temperatures too close to the pure Al-Ge eutectic value will therefore be at risk of not melting the layers. References [13] and [14] performed Al-Ge eutectic bonding of MEMS devices, finding a SiO2 barrier to be necessary to avoid Si ternary formation. Kirkendall voids are observed in literature [22], [23], [24] at Ge/Si or Ge/Al to indicate diffusion at material interfaces, and these can also compromise bond strength.…”

Section: Introductionmentioning

confidence: 99%

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Exploring Ru Compatibility With Al-Ge Eutectic Wafer Bonding

Ferguson

Najah

Banville

et al. 2022

J. Microelectromech. Syst.

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We explore compatibility of Ru with Al-Ge eutectic wafer bonding. We first present experiments to check for the presence of Ru ternary alloy poisoning inhibiting Al-Ge melting as well as evaluations of Al-Ge melt wettability on Ru and diffusion outcomes following bond-simulating anneals. Results show that Ru is stable with no observed microstructural changes or dissolution in the melt, indicating no ternary poisoning for the applied thermal budget. Ru was found to act as an effective barrier offering good melt wettability in all considered configurations with Al and Ge. From inspection of the binary constituents of Al-Ge-Ru we propose that Al-Ge eutectic melting temperature will decrease marginally for Ru contamination in a 1-2% range before a drastic increase in melting temperature (>10°C/% Ru) at higher Ru compositions. We then demonstrate wafer-level packaged 200 mm devices and MEMS with strong bond outcomes of devices bearing Ru contacts. We conclude that Ru has high compatibility with Al-Ge eutectic bonding.

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Low-temperature Al–Ge bonding for 3D integration

Cited by 8 publications

References 31 publications

Integrating MEMS and ICs

Integrating MEMS and ICs

Wafer-Level Vacuum Packaging of Smart Sensors

Exploring Ru Compatibility With Al-Ge Eutectic Wafer Bonding

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