Laser induced forward transfer of metals

Abstract

Laser Induced Forward Transfer (LIFT) is a direct-writing technique that allows depositing materials on unconventional substrates. Further it can be used to design complex patterns during transfer thereby reducing the tedious process of post-processing to get the desired shape. In this work Copper thin films have been transferred to flexible substrates through Laser-induced forward transfer (LIFT) micro-patterning. The ability to deposit patterns, spots, and lines, with sub-μm resolution may have applications in microelectronics as well as in the optoelectronics fabrication industries. In this work we demonstrate, direct micro deposition of high-quality patterns with sub-μm features using LIFT process. The present approach also exploits all advantages over conventional methods including simplicity in terms of vacuum handling, deposition purity, position selectivity, and high-accuracy sub-μm pattern transfer. The intensity and substrate heating on the transferred material is studied in detail. Nd:YAG laser having wavelength of 532 nm and 355nm (10 Hz) is impinged using single shots onto the target material through a focusing lens having 30 cm focal length. In this work, we have deposited both the micro patterns as well as 3D structures. The 3D structures are used in gas sensors to find velocity. The tip of the 3D structures is connected to the Atomic Force Microscope and subjected to a flowing gas. Since the pillar is fixed at one end it behaves like a cantilever beam. Now the deflection of the beam gives a measure of the velocity of the flowing gas. The structures are also used to find the leak detection.