Low-Temperature Wafer Bonding Using Solid-Liquid Inter-Diffusion Mechanism

Froemel, Joerg; Baum, Mario; Wiemer, Maik; Geßner, Thomas

doi:10.1109/jmems.2015.2455340

Cited by 24 publications

(20 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Drawbacks of solder bonding and eutectic bonding are that the melting of solder metals and alloys can cause reflow problems, and to ensure sufficient hermeticity and bond strength, the sealing ring widths typically are more than 100 µm [13], [14], [16], [18]. For SLID bonding, voids can occur in the intermetallic compound layer, and special care has to be taken in designing the sealing layer thickness and in controlling the temperature ramping during bonding to get uniform and strong bonds [19], [20], [28]. Surface activated bonding enables room temperature sealing [21], [29], but the requirements on surface planarity and surface roughness of the substrates are very high [21], [30].…”

Section: Introductionmentioning

confidence: 99%

Wafer-Level Vacuum Packaging Enabled by Plastic Deformation and Low-Temperature Welding of Copper Sealing Rings With a Small Footprint

Wang

Bleiker

Antelius

et al. 2017

J. Microelectromech. Syst.

View full text Add to dashboard Cite

Section: Introductionmentioning

confidence: 99%

Wafer-Level Vacuum Packaging Enabled by Plastic Deformation and Low-Temperature Welding of Copper Sealing Rings With a Small Footprint

Wang

Bleiker

Antelius

et al. 2017

J. Microelectromech. Syst.

View full text Add to dashboard Cite

“…Ga and In had also been used in SLID designs due to its low melting temperature. SLID joints made with Ag/In [9,10] and Cu/Ga [11,12] systems had been reported, where the IMC formation issue persists. A technique to eliminate the IMC region is to convert it into a solid solution phase by post-annealing, as demonstrated using the Ag/In system [13].…”

Section: Introductionmentioning

confidence: 99%

Low-pressure solid-state bonding technology using fine-grained silver foils for high-temperature electronics

Lee

2017

J Mater Sci

View full text Add to dashboard Cite

A solid-state bonding technique using fine-grained silver (Ag) foils is presented. The Ag foils are manufactured using many runs of cold rolling and subsequent annealing processes to achieve the favorable microstructure. X-ray diffraction and pole figure measurement are performed to examine the crystal structure and grain orientations. Si chips are bonded to bare Cu substrates using the Ag foil as the bonding medium at 300°C in 0.1 torr vacuum assisted by 6.9 MPa static pressure, which is much lower than that used in conventional thermal compression bonding. Cross sections prepared by focus ion beam show clear bonding interfaces with only a few voids smaller than 100 nm. The bonded structures do not crack after cooling down to room temperature, indicating that the ductile Ag layer is able to manage the strain induced by the large coefficient of thermal expansion mismatch between Si and Cu. The average shear strength of as-bonded samples is 29 MPa. High-temperature storage tests are conducted, and slight increase in strength can be observed after 300°C aging. Fracture analyses show that the breakage occurs within the Ag foil rather than on the bonding interface. Transmission electron microscopy and energydispersive spectroscopy (TEM/EDX) are conducted for Ag/Cu interface after 200-h aging, and the result shows that slight diffusion proceeds during the aging. Since Ag has the highest electrical and thermal conductivities among metals, therefore the bonded structures reported in this paper probably represent the best possible design for high-temperature and high-power electronic packaging applications.

show abstract

“…The bonding between a magnetron sputtered Cu layer and an electroplated Ga layer on a 50 nm Au seed layer has been investigated [ 61 ]. A schematic cross section of the interface to be joined is illustrated in Figure 4 a.…”

Section: Ga and Ga-based Alloys Applications In Microelectronic Inmentioning

confidence: 99%

“…One such method involves using a higher bonding temperature to mitigate the formation of the θ-CuGa 2 phase. Froemel et al [ 61 ] found that by increasing the annealing temperature (from 90 to 200 °C), the amount of CuGa 2 decreased, favouring the formation of Cu 9 Ga 4 , and the shear strength increased correspondingly. Another hypothesis considered that the cracks were formed during the liquid-solid reaction instead of the physical vibration [ 64 ].…”

Section: Characterisation Of Reactions Between Liquid Ga-based Allmentioning

confidence: 99%

“…Another kind of defect formed in the interface are Kirkendall voids, which are caused by the fast diffusion of the substrate materials into the molten Ga alloy [ 61 , 102 ]. Thus, the interdiffusion coefficient of the liquid/solid couple is an important consideration when selecting the joining alloy.…”

Section: Characterisation Of Reactions Between Liquid Ga-based Allmentioning

confidence: 99%

See 1 more Smart Citation

Ga-Based Alloys in Microelectronic Interconnects: A Review

et al. 2018

View full text Add to dashboard Cite

Gallium (Ga) and some of its alloys have a range of properties that make them an attractive option for microelectronic interconnects, including low melting point, non-toxicity, and the ability to wet without fluxing most materials—including oxides—found in microelectronics. Some of these properties result from their ability to form stable high melting temperature solid solutions and intermetallic compounds with other metals, such as copper, nickel, and aluminium. Ga and Ga-based alloys have already received significant attention in the scientific literature given their potential for use in the liquid state. Their potential for enabling the miniaturisation and deformability of microelectronic devices has also been demonstrated. The low process temperatures, made possible by their low melting points, produce significant energy savings. However, there are still some issues that need to be addressed before their potential can be fully realised. Characterising Ga and Ga-based alloys, and their reactions with materials commonly used in the microelectronic industry, are thus a priority for the electronics industry. This review provides a summary of research related to the applications and characterisation of Ga-based alloys. If the potential of Ga-based alloys for low temperature bonding in microelectronics manufacturing is to be realised, more work needs to be done on their interactions with the wide range of substrate materials now being used in electronic circuitry.

show abstract

Low-Temperature Wafer Bonding Using Solid-Liquid Inter-Diffusion Mechanism

Cited by 24 publications

References 31 publications

Wafer-Level Vacuum Packaging Enabled by Plastic Deformation and Low-Temperature Welding of Copper Sealing Rings With a Small Footprint

Wafer-Level Vacuum Packaging Enabled by Plastic Deformation and Low-Temperature Welding of Copper Sealing Rings With a Small Footprint

Low-pressure solid-state bonding technology using fine-grained silver foils for high-temperature electronics

Ga-Based Alloys in Microelectronic Interconnects: A Review

Contact Info

Product

Resources

About