Accurate two-dimensional simulation model and experimental demonstration in ultraviolet picosecond laser scribing ablation.

Laser patterning of copper thin films is essential for the electronics manufacturing industry. In this work, to efficiently and accurately describe the physics process of UV-ps laser ablating copper thin film, a two-temperature model (TTM) consisting of the electron-lattice system and phase explosion mechanism was proposed. The process of electron heating and electron-lattice heat transfer in single pulse ablation were revealed. The average relative errors (ARE) of simulated ablation depth and width were 6.24% and 4.82%, respectively. The process of laser scribing ablation presents the characteristics of repeated ablation in the overlapping ablation region and new ablation in the non-overlapping region. The physics essence of laser scribing is the multiple laser ablations with different energies on the cross-section. The laser scribing cross-section ablation was simulated on 2D TTM. Compared with 3D simulation, though the ARE of ablation depth and width of 2D simulation slightly increased from 15.81% and 5.69% to 18.96% and 8.76%, respectively, the average solving time decreased significantly, from 81960 s to 2140 s. This comprehensive study aims to offer some insights into the characteristics of UV-ps laser ablation of copper thin film.