Fabrication and characterization of gold-tin eutectic bonding for hermetic packaging of MEMS devices

Demir, Eyup Can; Torunbalcı, Mustafa Mert; Dönmez, İnci; Kalay, Yunus Eren; Akın, Tayfun

doi:10.1109/eptc.2014.7028329

Cited by 8 publications

(5 citation statements)

References 8 publications

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“…Samples that were heat-treated in a vacuum oven before final reflow successfully bonded only in 36% cases, while using the same temperature profile on samples without any prior annealing led to an increase in yield to 78% of well-sealed samples. Typically, pre-reflow annealing is employed to increase the bondability of as-deposited layers over time by minimising the rate of diffusion of Au into Sn and the formation of unwanted intermetallics [38]. However, in our case annealing negatively impacted bonding process yield likely as a result of increased Ti adhesion layer consumption.…”

Section: Resultsmentioning

confidence: 88%

Hermetic chip-scale packaging using Au:Sn eutectic bonding for implantable devices

Szostak

Keshavarz

Constandinou

2021

J. Micromech. Microeng.

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Advancements in miniaturisation and new capabilities of implantable devices impose a need for the development of compact, hermetic, and CMOS-compatible micro packaging methods. Gold-tin-based eutectic bonding presents the potential for achieving low-footprint seals with low permeability to moisture at process temperatures below 350 ∘C. This work describes a method for the deposition of Au:Sn eutectic alloy frames by sequential electroplating from commercially available solutions. Frames were bonded on the chip-level in the process of eutectic bonding. Bond quality was characterised through shear force measurements, scanning electron microscopy, visual inspection, and immersion tests. Characterisation of seals geometry, solder thickness, and bonding process parameters was evaluated, along with toxicity assessment of bonding layers to the human fibroblast cells. With a successful bond yield of over 70% and no cytotoxic effect, Au:Sn eutectic bonding appears as a suitable method for the protection of integrated circuitry in implantable applications.

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Section: Resultsmentioning

confidence: 88%

Hermetic chip-scale packaging using Au:Sn eutectic bonding for implantable devices

Szostak

Keshavarz

Constandinou

2021

J. Micromech. Microeng.

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“…Due to a number of inherent advantages, Au 0.8 Sn 0.2 eutectic bonding has been heavily researched for WLVP packaging and demonstrated using surrogate proxy wafers [31,32,33,34,35,36], RF MEMS switches [37,38], MEMS resonators [39], and infrared imaging smart sensors [40]. In this approach, Au 0.8 Sn 0.2 is deposited on either the lid or device wafer, and a wettable layer, typically Au, is deposited on the other wafer.…”

Section: Bonding Approachesmentioning

confidence: 99%

“…Once the layers are deposited, the stack is annealed to create the Au 0.8 Sn 0.2 eutectic material. This deposition approach has been demonstrated for both the IC interconnect [41,51,52] and hermetic MEMS packaging [31,32,33,37,38]. Figure 4 depicts an implementation of this approach in the fabrication of a WLVP for an RF resonator device with vertical feedthroughs [35].…”

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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“…Wang et al have performed eutectic bonding with the Au-Sn system at temperatures below 300℃ for hermetic sealing [4]. An average thickness of less than 1.5 µm of the Au-Sn layer was used to perform the eutectic bonding process, which can reach an average shear strength of approximately 23 MPa [5]. However, failure occurred due to the stress produced during the bonding process by the mismatch of the thermal expansion coefficients between the die and the bonding layer [6].…”

Section: Introductionmentioning

confidence: 99%

Sputtering of Ultra-thin Ag Nano-twinned Films on Si Wafers for the Applications in TSV Interconnection of 3D-IC Advanced Packages Copper Solvent Extraction

Chen,

Yang,

Chen

et al. 2023

Proceedings of the 9th World Congress on Mechanical, Chemical, and Material Engineering

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Nanotwinned structure has been attracting a great deal of attention due to their excellent mechanical and electrical properties. In this study, ultra-thin nanotwinned Ag films can be fabricated by DC magnetron sputtering with moderate substrate bias. Within these nanotwinned films, only 100-400 nm thick equiaxed-grin transition layer was formed between the nanotwinned region and Si substrate observed by Focused ion Beam (FIB). For the analysis of nanotwinned films, the as-deposited films are shown to have a strong (111) preferred orientation. The roughness of the films was observed below 10 nm, which was smooth enough and acceptable for metal direct bonding. Ag-to-Ag direct bonding was then performed to satisfy the requirement of TSV interconnections. The ultra-thin nanotwinned Ag films with (111) preferred orientation will have many potential applications in interconnects and 3D IC packaging.

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Fabrication and characterization of gold-tin eutectic bonding for hermetic packaging of MEMS devices

Cited by 8 publications

References 8 publications

Hermetic chip-scale packaging using Au:Sn eutectic bonding for implantable devices

Hermetic chip-scale packaging using Au:Sn eutectic bonding for implantable devices

Wafer-Level Vacuum Packaging of Smart Sensors

Sputtering of Ultra-thin Ag Nano-twinned Films on Si Wafers for the Applications in TSV Interconnection of 3D-IC Advanced Packages Copper Solvent Extraction

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