Improving the quality of the crystallinity of Cu films by non-thermal high-frequency electric current treatment

Abstract This study investigates the effects of high-frequency alternating current (AC) treatment on the microstructural evolution and electrical properties of electron-beam-deposited Cu thin films. After 60 min of AC treatment at a frequency of 500 kHz, the resistivity of the Cu thin films decreased to 97.9%, 95.6%, and 94.1% of their initial values at current densities of 30, 40, and 50 kA mm −2 , respectively. COMSOL simulations confirmed that the maximum temperature rise did not exceed 50 °C, demonstrating that the process was dominated by the applied current rather than thermal effects. Quasi- in-situ electron backscatter diffraction results revealed that, under the 50 kA mm −2 condition, AC treatment increase the average grain size from 0.263 μ m to 0.432 μ m and reduced kernel average misorientation from 0.595 to 0.540. Unlike conventional thermal annealing, which relies on random atomic diffusion, AC treatment imparts a directional driving force that enhances the <101> texture in the current direction. These findings demonstrate that high-frequency AC treatment is an efficient, non-thermal processing method that can enhance crystallinity and electrical conductivity of Cu films under near-room-temperature conditions (below 50 °C). In addition, this approach offers controllable regulation of grain orientation, indicating strong potential for applications in semiconductor interconnects, microelectronics, and advanced thin-film technologies.