Experimental investigation of laser induced forward transfer process of metal thin films

Dependence of size accuracy of deposited structure on the film–acceptor substrate distance and fluence, and the factors which influence the dependences were investigated. Au and Ni thin films of several tens to hundreds of nanometer thickness deposited on quartz substrates using ion sputtering deposition were irradiated by single pulse of KrF excimer laser (wavelength: 248 nm, pulse width 30 ns). Changes in the intensity of reflected He–Ne laser from the front and rear sides of the thin films show that film removal finishes during the excimer laser pulse. Plume images and shadowgraphs of transferring materials show that the velocity of both the leading edge of the plume and the transferring materials become faster with increasing fluence, and that the transferring material precedes the plume. At lower fluences, the deposited structure shows bad appearance due to incomplete removal from the support substrate. At higher fluences, the big shock causes the wide range of spread of deposited structure when the transferring particles have a collision with the acceptor substrate. At optimum fluences, high size accuracy of the deposited structure is achieved when the film–substrate distance is made as short as possible.