Microdroplet deposition of copper film by femtosecond laser-induced forward transfer

Copper microdroplets were deposited onto a quartz substrate by the laser-induced forward transfer (LIFT) using laser pulses of 148 fs at a center wavelength of 775 nm. The droplets with 2-3 mu m diameters were transferred at a laser pulse energy slightly above the threshold at which the copper film could be removed completely. The droplet formation was a result of the blow-off of a molten film from the quartz substrate by a compressive stress of plasma when the free surface was melted and was different from the microdroplet formation by the LIFT technique using nanosecond laser pulse. (c) 2006 American Institute of Physics.