Laser printing of large-scale metal micro/nanoparticle array: Deposition behavior and microstructure

In this study, a novel printing process is proposed to efficiently fabricate a large-scale micro/nanoparticle array via laser-induced forward transfer of femtoliter metal voxels. A sputtering metal film with sub-micrometer thickness was initially patterned to an independent voxel array using a picosecond laser. Then, an ultraviolet nanosecond laser induced the voxel transfer from the donor substrate to the receiver entirely after it was irradiated by a single laser pulse. The results indicated that single laser irradiation can print a microparticle array that covers an area of several millimeters. The printed microparticle size varied from 5 μm to 580 nm. Furthermore, the proposed printing process exhibited high controllability by adjusting the voxel volume. The morphology of the cross section of the printed copper microparticles exhibited a lower porosity and oxidation state, and ultrafine nanograins were generated within an amorphous shell. The location deviations of the printed microparticles obeyed the chi-square distribution with a mean value of 1 μm. Moreover, the proposed process can avoid the satellite microdroplets and debris for reducing the resolution because unstable jetting and microdroplet separation are eliminated. The proposed approach enables the printing of a large-scale microstructure array with high efficiency and flexibility.