Metallurgical challenges in microelectronic 3D IC packaging technology for future consumer electronic products
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- Tu, K.N. & Tian, T. Sci. China Technol. Sci. (2013) 56: 1740. doi:10.1007/s11431-013-5261-y
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Metallurgical challenges in controlling the microstructural stability of Cu and solder microbumps in 3D IC packaging technology are discussed. Using uni-directional 〈111〉 oriented nanotwinned Cu, the controlled growth of oriented Cu66n5 on the nanotwinned Cu and its transformation to Cu3Sn without Kirkendall voids have been achieved. In order to join a stack of Si chips into a 3D device, multiple reflows of solder microbumps may be required; we consider localized heating to do so by the use of self-sustained explosive reaction in multi-layered Al/Ni thin films of nano thickness. It avoids re-melting of those solder joints which have been formed already in the 3D stacking structure.