Short and ultrashort pulsed laser-based micro-scribing of copper film on a dielectric substrate for functional devices

In this work, micro-scribing of Cu film on a dielectric substrate with lasers having different pulse duration (6 ns, 500 ps, 1 ps, 120 fs) has been analyzed. The recast layer formation near the microchannel is clearly observed in the case of 6 ns and 500 ps laser-based scribing. On the other hand, 1 ps and 120 fs pulsed lasers were able to produce microchannel without observable recast layer. Based on the XRD analysis, compressive residual stresses are observed in the scribed region with the 6 ns and the 500 ps laser, whereas tensile residual stresses are measured in the scribed region with the 1 ps and the 120 fs lasers. Oxide layer formation was observed in the case of all the pule regimes. A theoretical simulation was developed to estimate the temperature on the dielectric substrate. Complete removal of Cu from the dielectric will resulted in thermal damage to the substrate. A hybrid micro-scribing technique, where the sample was immersed in NaCl solution during the final laser scan was demonstrated in the case of nanosecond laser. Finally, a frequency selective surface (FSS) was fabricated with the help of the hybrid scribing technique.