[25p-E307-1~15] 13.5 Semiconductor devices/ Interconnect/ Integration technologies

▲ [25p-E307-7] Fabrication and Characterization of Ultrahigh Strength Ni-TiO₂ Composite Coatings Electroplated with Supercritical Carbon Dioxide Emulsified Electrolyte

〇Yuan Chien¹, Chun-Yi Chen¹, Masato Sone¹, Tso-Fu Mark Chang¹ (1.Tokyo Tech)

Keywords:metal matrix composites, electroplating, supercritical carbon dioxide

Metal matrix composites (MMCs) are composite materials of which the physical and chemical properties are reinforced by allowing dispersion of nanoparticles into the metal matrix . Electroplating was proved as a reliable process for incorporating nanoparticles into matrix and enhanced the mechanical strength of metal matrix in microelectromechanical systems (MEMS) .In this work, Ni-TiO₂ composite films were electroplated on Cu plates using Ni Watts bath-based electrolyte containing 30 g/L TiO₂ nanoparticles. A constant current of 3 ASD was applied to the Cu electrode for 40 min with the assistance of SC-CO₂ at 15MPa and 50°C. The amount of TiO₂ in Ni-TiO₂ composite films were evaluated by energy dispersive X-ray spectroscopy and the uniformity of TiO₂ in the Ni matrix was quantified by coefficient of variation of Ti amount per unit area in the elemental mapping region of heatmap. The Vickers hardness of SC-CO₂ assisted Ni-TiO₂ was improved to 1167HV from that of conventional Ni-TiO₂ (360HV). Micro-pillars in dimensions of 10 μm × 10 μm × 20 μm were fabricated from Ni-TiO₂ with and without assistance of SC-CO₂ for examining the mechanical properties of Ni-TiO₂ composite films in micrometer-scale. Yield strength of the pillar fabricated from SC-CO₂ assisted Ni-TiO₂ was 3.37 GPa, which was proper for high strength applications in MEMS devices.