Direct patterning of double-layered metal thin films by a pulsed Nd:YAG laser beam

Metal thin-film patterning is of technological significance because modern electronic devices commonly require an electrode or metallization pattern. There are many cases where this pattern consists of two different metallic layers in order to improve the mechanical and electrical contact. We here show that double-layered metal thin films evaporated on glass can be directly patterned by a spatially-modulated pulsed Nd-YAG laser beam incident from the backside of the substrate. This method utilizes a pulsed laser-induced thermo-elastic force exerting on the film which plays a role to detach it from the substrate. Since the film is polycrystalline with nano-sized grains, a spatially-modulated thermo-elastic force may enable selective removal of the material by shearing along the weakly-bonded grain boundary regions. Many different combinations of Al, Ag, and Au layers have been investigated and their pattern fidelity and morphology are discussed, along with the simulation results for double-layered nanocystalline films.