Rapid fabrication of conductive copper patterns on glass by femtosecond Laser-Induced reduction

In a wide range of applications, rapid fabrication of metallic patterns on a transparent substrate is highly desired. In this work, a highly conductive Cu wire with a sheet resistance of 0.27 Ω/sq is deposited on glass through femtosecond laser-induced reduction of Cu ions. The present work improves the deposition efficiency by at least one order of magnitude compared to previous works. The effects of scanning speed, laser intensity, and effective pulse number on composition, morphology, dimensions, and conductivity of the deposited Cu are investigated. The process window is established with the goal of achieving optimal laser parameters for creating highly conductive Cu. With a scanning speed of 600 mm/s, an intensity of 1.21 × 1010 W/cm2, and an effective pulse number of 38500, the well-formed Cu in the process window has a sheet resistance of less than 1 Ω/sq and the highest deposited efficiency of 4.60 × 107 μm3/s. The current-carrying performance of the deposited Cu is also investigated for prospective use as a circuit material, demonstrating the Cu wire's electrical and thermal durability. In addition, temperature rise could be estimated from Cu wire width and sheet resistance with given Cu wire length and applied current, which could aid in laser parameter selection.