Suppression of Void Formation at Sn/Cu Joint Due to Twin Formation in Cu Electrodeposit
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The use of organic additives is crucial for Cu electrodeposition. However, specific impure species originating from the additives are incorporated in the Cu electroplated layer, causing serious reliability problems such as void formation at the solder/Cu joints. In this study, three Cu substrates were electroplated using various additive formulas. The use of organic additives results in an incorporation of a higher level of impurity in the Cu-electroplated layers and also affects the atomic deposition behavior of Cu which alters the grain microstructures. By using a specific additive formula, the grain growth of Cu evolves into a slender structure with a high density of twins. Thermal aging experiments of the Sn/Cu joints show that the void formation is successfully suppressed at the joint using a slender-grained Cu substrate, and that the suppression effect is attributed to the high microstructural stability of the twinning structure.
This work was financially supported by the “Innovation and Development Center of Sustainable Agriculture” from The Featured Areas Research Center Program within the framework of the Higher Education Sprout Project by the Ministry of Education (MOE) in Taiwan. This work was also financially supported by the Ministry of Science and Technology of Taiwan through Grant No. MOST-106-2221-E-005-066-MY3. The authors also thank the Lin Trading Co., Ltd. in Taiwan for kindly offering the 3D optical profiler for the topographical examination of the as-electroplated Cu layers.
- 6.Z.V. Feng, X. Li, and A.A. Gewirth, J. Phys. Chem. B 9415, 107 (2003).Google Scholar