Fabrication of Micro Copper Walls by Localized Electrochemical Deposition through the Layer by Layer Movement of a Micro Anode

Abstract

The process of localized electrochemical deposition (LECD) offers the potential to fabricate complex structures using the layer-bylayer movement of an anode or a cathode, similar to 3D printing. This work demonstrates the fabrication of micro sized copper walls using the LECD process, which is critical for MEMS and semiconductor-related applications. First, copper walls with different morphologies were deposited by moving the micro anode layer by layer and controlling the applied voltage between the electrodes during LECD. Next, the effect of the deposition voltage and anode trajectory (layer height and step length) on the profile of copper walls and the roughness of the wall surface were studied. It was found that the deposition voltage and layer height significantly influenced the profiles and deposition rates. Under applied voltage in the range 2.8-3.0 V and with a layer height of 2 μm, copper walls with a completely densified surface can be obtained. Finally, three copper wall growth patterns, namely, parallel column growth, spaced column growth and bifurcated column growth, were proposed to describe the wall growth mechanism.

Fabrication of Micro-Sized Copper Columns Using Localized Electrochemical Deposition with a 20 μm Diameter Micro Anode

“…[9][10][11][12] In addition, by using the MAGE technique, various shapes and complicated geometries can be fabricated by moving the tip of the microanode to form the required track, such as copper walls, helical structures, etc. [13][14][15] Significant research effort has been devoted to investigating and improving the LECD technique. Yeo et al reported that ultrasonic vibrations can be used to increase mass transport at a localized region leading to a high rate of deposition; this improves the concentricity and increases the porosity of the fabricated columns.…”

Fabrication of an X-shaped micro-copper structure containing a merging joint based on localized electrochemical deposition

“…However, most of the aforementioned studies have focused on column deposition [30] and the production of extended structures [31]. In 2000, Johansson et al used LECD to prepare a nickel column and deposited a portal made by bridging two separately built structures [32], but the joining structure was not fully formed.…”

Fabrication of n-shaped micro copper structures through localized electrochemical deposition

“…To improve the conformational design complexity of threedimensional (3D) microproducts, Ciou et al combined the LECD process with a real-time 3D image feedback distance control system and fabricated two types of 3D microstructures: helical springs with a low pitch angle and inverted tripods [16]. Wang et al used a novel LECD system by moving the micro anode layer-by-layer and controlling the applied voltage between the electrodes to fabricate copper walls [17].…”