Laser curing of gold nanoparticle inks

The concept of effective laser curing of nanoparticle suspensions (NPS) with a laser beam is presented in this paper. A toluene solvent is employed as the carrier of gold nanoparticles possessing a lower melting temperature than thatof bulk gold. Using a modified drop-on-demand jetting system, the gold nanoparticle suspended solution is printed on a glass substrate and cured with laser irradiation. The laser energy coupling to the nanoparticles in conjunction with thermocapillary effects and the evaporation of the solvent are critical to the quality of the electrically conductive gold micro-lines. By employing a intensity-modulated double laser beam processing scheme, to optimize the curing process, it is demonstrated for the first time, that the gold nanoparticles could be sintered on a glass substrate to form a gold line of resistivity close to that of bulk gold. This is a noticeable result, compared to recently published microconductor manufacturing with nanoparticle suspensions with oven or low power single laser beam curing reporting resistivities four to five times higher than that of bulk gold. As a consequence, in addition to their scientific value, the current results demonstrate the potential of laser printing for use in the microelectronics manufacturing for the first time. It was also shown that the morphology of the gold line could be modified by appropriate design of the shape of the processing laser beam.