Texture Modulated Cobalt Film with Improved Soft Magnetic Properties for Low-loss High-frequency Signal Transmission

The rapid development of high-speed and miniaturized communication technologies imposes stringent demands on the performance of signal transmission materials. With the signal frequency increasing, conductor losses caused by skin effects and eddy current losses posing significant challenges to high-frequency signal integrity. Electrodeposited coatings with superior soft magnetic properties have emerged as a promising solution for enhancing radiofrequency (RF) device performance. In this work, benzenesulfonic acid (BNS) was systematically investigated as an additive to optimize the soft magnetic properties of electrodeposited cobalt (Co) films. Electrochemical analysis and atomic force microscopy (AFM) revealed that BNS accelerated Co deposition and obtained films with reduced surface roughness. Compared to VMS-Co films, BNS-Co films exhibited a 17.6% enhancement in saturation magnetization (Ms) and reduced coercivity (Hc) from 120 Oe to 20 Oe, indicated significantly improved soft magnetic behavior. Further research confirmed that the improvement in the soft magnetic properties of BNS-Co was attributed to the enhancement of (002) texture and reduction in impurity content. This work presents a novel strategy for low-loss high-frequency signal transmission conductors through additive-assisted electrodeposition.