High aspect ratio 3-D electroplating assisted by localized laser irradiation

We report a high-aspect ratio electroplating technique that is assisted by focused laser irradiation to construct further narrow and tall three-dimensional (3-D) microstructures. Focused laser irradiation strengthens localized electrical field near the focal spot, thus enabling faster nucleation of ions and construction of higher aspect ratio pillars than typical chemical electroplating. We compared electroplating properties with and without laser irradiation, by investigating the profile, speed, and material elements of the fabricated microstructures. Laser-assisted electroplating enhanced the basement deposition speed by 31% to 1.7 nm/s from the 1.3 nm/s of the traditional electrochemical deposition without laser irradiation under a low current density (4 mA/cm²). This technique allowed vertical pillars to grow in a reduced diameter of 85 urn, which is down by 20% compared to the diameter of 110 urn without laser assistance. The electroplated nickel pillars have resulted in 24% less oxygen in the final structures showing the improved homogeneity of materials. Lateral nickel branches are also produced with a higher deposition rate than traditional method.