Ultra-short laser pulse interaction with nickel films

Laser induced forward transfer method involves three sequence of events (i) laser pulse heats up the front surface of the film until it melts (ii) the melt front propagates through the film until it reaches the back surface and finally (iii) at or close to melt-through the metal vapour pressure at the front propels the molten film to the substrate. Many authors have shown potentials of this method in direct writing and photo-mask repair. In this paper, laser induced forward technique is applied to nickel films of thicknesses 98nm, 200nm and 322nm by using Ti: Sapphire femtosecond laser. Threshold energies for both direct and backside ablations are calculated. The feasibility of the transfer process is also demonstrated on nickel film on silicon wafer. Elevated features observed on some films during transfer process have been explained.