Nanosecond pulse laser scribing using Bessel beam for single shot removal of transparent conductive oxide thin film

Nanosecond laser Bessel beam scribing on the TCO thin film was investigated to improve processing precision and robustness of optical system. Fundamental wave (1064 nm) of Nd:YAG laser was shaped into high-quality Bessel beam by using novel optical system consisting of axicons and convex lens. Spatial FWHM of the beam was only 1.5 μm in the present context, and significantly precise scribing with minimum width of 2.3 μm was achieved on 600-700 nm-thick FTO film with electrical isolation. Furthermore, due to the critically deep focal length of millimeters-order, robustness on sample positioning was greatly improved. Additionally, experimental results showed that single shot removal of entire film can be achieved using film side irradiation unlike conventional Gaussian beam. Temperature distribution during the process was calculated by a numerical model in which we have taken into account beam propagation inside the film to give comparison with a Gaussian beam irradiation. The calculation results showed that only Bessel beam is self-reconstructed behind plasma shielding so that entire film can be removed by single shot. Our findings suggest that Bessel beam can be used for efficient IR scribing with significantly high quality without selecting substrate material.