Local electroplating deposition for free-standing micropillars using a bias-modulated scanning ion conductance microscope

Abstract

A local electroplating metal microdeposition process with a fine positioning mechanism on a nanopipette was developed. The fine positioning was achieved with a bias-modulated scanning ion conductance microscope (BM-SICM) using a single-aperture nanopipette. Using the modulated sensing signal (e.g., sinusoidal signal), the deposition by electroplating was prevented during the positioning. To demonstrate the deposition process, simple micropillars were fabricated. In a single-step deposition process, an array of copper pillars with diameters of 4.3–5.1 μm and lengths of 20 μm was fabricated. The disconnection of the pillars during the fabrication process occurred at fabrication velocities higher than 0.82 μm/s. To enable deposition without a closed-loop control, a multistep deposition process was introduced by repeating the deposition process and fine positioning steps at the growing end of the pillar. Using this multistep deposition process high-aspect pillars that were connected in 21 and 9 cycles were fabricated with the DC voltage of 0.7 and 1.0 V, respectively at a velocity of 0.82 μm/s. This simple deposition technology with BM-SICM will contribute to microfabrication technologies.