Diffusion-Reaction in the Au-Rich Ternary Au-Pt-Sn System as a Basis for Ternary Diffusion Soldering

Grolier, Vincent; Schmid–Fetzer, Rainer

doi:10.1007/s11664-008-0407-6

Cited by 8 publications

(3 citation statements)

References 58 publications

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“…3 with significant solid solubility, a low melting filler material and no intermetallic phases occurring at the bonding temperature. No intermetallic phases are formed in the bond during the diffusion brazing process in contrast to soldering or diffusion soldering [15][16][17] which is ruled by different phase diagrams.…”

Section: Phase Diagram Applications Exemplified With Cu-nimentioning

confidence: 98%

Phase Diagrams: The Beginning of Wisdom

Schmid–Fetzer

2014

J. Phase Equilib. Diffus.

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This work presents a primer on ''How to Read and Apply Phase Diagrams'' in the current environment of powerful thermodynamic software packages. Advanced aspects in that context are also covered. It is a brief guide into using this cornerstone of knowledge in materials science and engineering and offers assistance in the proper interpretation of results obtained from stateof-the-art Calphad-type thermodynamic calculations. Starting from the very basics it explains the reading of unary, binary and ternary phase diagrams, including liquidus projections, isothermal and vertical phase diagram sections. Application examples are directly derived from these phase diagrams of Fe, Cu-Ni, Mg-Al, and Mg-Al-Zn. The use of stable and metastable phase diagrams and appropriate choices of state variables are explained for the relevant Fe-C and Fe-C-Si systems. The most useful concept of zero-phase fraction lines in phase diagram sections of multicomponent systems is made clear by coming back to the Cu-Ni and Mg-Al-Zn systems. Thermodynamic solidification simulation using the Scheil approximation in comparison to the equilibrium case is covered in context of multicomponent multiphase solidification and exemplified for Mg-Al-Zn alloys. The generic approach is directly applicable for all inorganic materials, but exemplified in this concise work for a small selection of metallic systems to highlight the interdependences among the phase diagrams. The embedded application examples for real material systems and various materials processes also emphasize the use of phase diagrams for the path from initial off-equilibrium state towards equilibrium.

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Section: Phase Diagram Applications Exemplified With Cu-nimentioning

confidence: 98%

Phase Diagrams: The Beginning of Wisdom

Schmid–Fetzer

2014

J. Phase Equilib. Diffus.

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“…3(e), and results indicated that the bright phase is an Au 4 Ti phase with a small solubility of tin. There is no comprehensive description of this phase available, and as the phase is thin (∼100 nm) even after annealing, it has been difficult to evaluate this phase even with STEM and nanospot-EDS [24]. Experimental results and reasoning by Grolier and Schmid-Fetzer [24] regarding the Au4Ti phase, experimental TEM results presented by Ivey [31], and thermodynamic reasoning of binary compound formation enthalpies by Ghosh [32] all support the formation of Au4Ti with a small solubility of Sn between the (Au,Pt)Sn and Ti/Mo during the bonding process.…”

Section: A Microstructural Analysismentioning

confidence: 99%

“…Platinum has been studied as a barrier metal for eutectic Au-Sn solder, nonetheless the experimental results indicate a rapid dissolution of the Pt into the Au-Sn system [19]- [24], which raises the remelting temperature of the solder [21], [24], [25]. The increase of the remelting temperature is one of the main advantages of the SLID bonding, as it enables further high-temperature processing, such as subsequent assembly steps and getter activation (>300°C ∼15 min) of MEMS devices [4], and it also enhances the reliability at high operational temperatures.…”

Section: Introductionmentioning

confidence: 99%

Wafer-Level AuSn/Pt Solid–Liquid Interdiffusion Bonding

Rautiainen

Vuorinen

Heikkinen

et al. 2018

IEEE Trans. Compon., Packag. Manufact. Technol.

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In this paper, wafer-level AuSn/Pt solid-liquid interdiffusion bonding for hermetic encapsulation of microelectromechanical systems (MEMS) is evaluated. Although AuSn is used for bonding of ICs, the implementation of AuSn diffusion bonding in MEMS applications requires thorough understanding of its compatibility with the complete layer stack including adhesion, buffer, and metallization layers. Partitioning of the layer stacks is possible in MEMS devices consisting of several silicon wafers since the device wafer carrying functional structures and the encapsulation wafer have different restrictions on process integration and applicable metal deposition techniques. In this paper, CMOS/MEMS compatible sputtered platinum is utilized on the device wafer as a contact metallization for Au-Sn metallized cap wafer. The role of the platinum layer thickness as well as the nickel and molybdenum buffer layers on mechanical reliability were tested. The mechanical shear and tensile tests were performed for samples after bonding as well as after high-temperature storage and thermal shock tests. The results were rationalized based on the combined microstructural, thermodynamic, and fracture surface analyses. High-strength and thermodynamically stable bonds were achieved, exhibiting shear strength up to ∼180 MPa and tensile strength up to ∼80 MPa. Platinum was consumed completely during bonding and was observed to dissolve mainly into the (Au,Pt)Sn phase. Thicker platinum layer (200 versus 100 nm) increased the (Au,Pt)Sn phase thickness and resulted in higher strength. The molybdenum buffer layer under the platinum metallization increased the tensile strength significantly.

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