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Abstract: The interfacial reactions of the Pd-plated Cu (Pd–Cu) ball bond and 4N Cu (Cu) ball bond on Al were investigated through PCT (Pressure Cooker Test) and HTST (High Temperature Storage Test) tests. The thickness of the interfacial Cu–Al IMC increases as the testing time increases. The Cu Al IMC growth rate was found to be slower in the Pd Cu ball bond than in the Cu ball bond. The growth of the IMC is diffusion-controlled during aging. During the test, the Pd diffuses from the interior of the Pd Cu ball toward the bond interface. FIB (Focus Ion Beam) studies show crack formation at the Cu Al IMC/Al interface in the Cu ball bond. During aging, the Pd-rich layer affected the interdiffusion between Cu and Al and may influence the IMC formation. The Pd Cu ball bond showed better bonding reliability than the Cu ball bond in all tests. [Copyright &y& Elsevier]

Abstract Transition metal silicide nanowires exhibit low resistivity, great thermal stability and excellent mechanical strength, contributing to their applications as interconnection and contact materials for future integrated circuits devices. In this work, we successfully fabricated two kinds of chromium silicide/silicon heterostructure nanowires through solid state reactions — bare Si/Cr 3 Si nanowires and Si/Cr 5 Si 3 -Al 2 O 3 core-shell nanowires. The growth behaviors and diffusion mechanisms of the two silicide heterostructure nanowires were investigated with in-situ TEM at 700 °C. During the growth of chromium silicide nanowires, unique amorphous Si phase would form first in front of silicide nanowires. Also, we found that oxide-shell could control the diffusion process in silicon nanowires. With oxide-shell, compression stress would restrain the growth of chromium silicide in the radial direction but accelerate its growth rate in the axial direction. Additionally, Al 2 O 3 shell reduced the radial expansion of chromium silicide nanowires and hindered Cr-rich phases with Cr 5 Si 3 appearing as the first phase. The crystal structures of the nanowires have been identified to be single-crystalline A15 and D8m type structure of the intrinsic Cr 3 Si nanowires and Cr 5 Si 3 nanowires, respectively. In addition to fundamental science, the significant study is beneficial for future processing techniques in nanotechnology and related applications. Graphical abstract With in-situ transmission electron microscopy (TEM), we successfully transformed single crystalline Si nanowires to chromium silicide/Si nanowire heterostructures. Also, during the solid state phase transformation process, we observed unique structures at the interface, demonstrated to be amorphous Si phase after Si Si bond breaking, which led the chromium silicide nanowire growth by interface-reaction control. Unlabelled Image Highlights • We utilized solid state reactions to fabricate controllable and unique Cr 3 Si/Si and Cr 5 Si/Si nanowire heterostructures. • With in-situ transmission electron microscopy (TEM), we observed a special interfacial reaction during the silicidation. • The design of Si-Al 2 O 3 core-shell effectively improved the morphology and crystallinity of the nanowire heterostructures. • We used distinctive methods and results to systematically investigate the kinetics of the nanowire heterostructures. [ABSTRACT FROM AUTHOR]