High-Frequency Pulse-Assisted Micro-Jet Electrochemical Deposition of Copper for High-Performance Interconnect Structures: Grain Refinement, Enhanced Mechanical Strength, and Corrosion Resistance

Micro-jet electrochemical deposition, with concentrated current, fast deposition and flexible fabrication, is widely used in metal additive manufacturing. However, its direct-current mode suffers from low efficiency, poor surface quality and inferior material performance. To overcome these limitations, high-frequency pulse power is adopted for copper electrodeposition. First, current density, electric field distribution, copper pillar growth and grain evolution are simulated under various electrical parameters. Second, Taguchi experiments identify optimal pulse parameters. Third, XRD and EBSD characterize grain structures of pulse and DC-deposited specimens comparatively. Finally, nanoindentation and electrochemical tests evaluate mechanical and anti-corrosion performances. The surface roughness of copper pillar samples printed under optimal parameters can reach 69nm. Grains are refined from micrometer to nanometer scale with 0.203 nm atomic spacing. The optimized high-frequency-pulse copper pillar achieves a hardness of 4757.2 MPa, 1109.7 MPa higher than its DC-deposited counterpart. It has a self-corrosion potential of −0.3021 V (vs. −0.4187 V for DC sample) and a corrosion current density of −1.545 A/cm² (vs. −0.8761 A/cm²). The results show markedly improved mechanical properties and corrosion resistance. High-frequency pulse micro-jet electrodeposition improves performances via grain refinement and is promising for electrodeposited metal structure fabrication.