Micron-scale copper wires printed using femtosecond laser-induced forward transfer with automated donor replenishment

We demonstrate the use of laser-induced forward transfer (LIFT) in combination with a novel donor replenishment scheme to print continuous copper wires. Wires of mm length, a few microns wide and submicron in height have been printed using a 800 nm, 1 kHz repetition rate, 150 fs pulsed laser. A 120 nm thick copper donor was used along with laser pulse energy densities of 0.16-0.21 J cm−2 to print overlapping few-micron sized pads to form the millimeter long wires. The wires have a measured resistivity of 17 ± 4 times that of bulk copper.