Process-Structure-Property Relationships in Meniscus-Confined Electrodeposition of 3D Copper Microcomponents

Although Meniscus-Confined Electrodeposition (MCED) is a promising micro/nano additive manufacturing technology, achieving precise control over deposition quality still faces significant challenges. This study systematically investigated the effects of applied voltage, withdrawal speed, and electrolyte pH on copper microstructures. Mechanistic analysis revealed that applied voltage drives a "solid-concave-solid" transition via the competition between outward capillary and inward thermal Marangoni flows, followed by a shift to kinetic control, while instantaneously regulating lateral dimensions through electrowetting, achieving a precise 50.9% diameter regulation rate within the linear region. Furthermore, real-time current signal analysis captured the adaptive transition from metastable to steady states, establishing a dynamic balance between nozzle withdrawal and deposition rate to ensure process continuity. Through comparative studies, pH 1.0 was identified as the optimal process point. AFM analysis showed that the printed structures have extremely high surface quality, with a sidewall root-mean-square roughness of only 1.06 nm. The printed features exhibit a high copper purity of 98.94% and demonstrate excellent electrical reliability, sustaining a stable current of up to 50 mA (current density ∼8.6 × 10⁵ A cm^-2), which robustly validates the structural densification. This work provides a theoretical foundation for MCED optimization and highlights its potential for next-generation 3D integrated circuits.