Electrodeposition of (111)-Oriented Cu Using Accelerator for Cu-Cu Direct Bonding

초록

With the increasing demand for higher integration and scaling in advanced electronic systems, Cu-Cu direct bonding has attracted significant attention as a key interconnect strategy. Achieving a highly oriented Cu surface, particularly with a (111) preferred orientation, is known to be beneficial for bonding reliability because of its low surface energy and favorable diffusion characteristics. In this study, we introduce a novel inorganic additive designed to modulate Cu electrodeposition behavior and crystallographic texture. The electrochemical influence of the additive was investigated using cyclic voltammetry (CV) and electrochemical quartz crystal microbalance (EQCM), while microstructural evolution and texture development were characterized by X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). The results reveal that the additive alters Cu reduction behavior and promotes the formation of a (111) preferred orientation. The enhanced (111) texture suggests that the additive-assisted Cu films may exhibit advantageous characteristics for low-temperature Cu-Cu direct bonding below 250 °C. These findings provide insights into additive-driven crystallographic control and its potential implications for next-generation bonding technologies.

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