257 nm Deep UV Femtosecond Laser Ablation with Minimized Crack and Chipping on Display Ultra-Thin Glass

Glass is widely used for various applications, including flat panel displays, solar panels, architectural windows, and exterior materials. These applications exhibit increasing complexity and improved functionality. In particular, glass substrates used in display panels require diverse forms of processing, prompting the exploration of laser applications to enhance processing quality, yield, and efficiency. This study aims to investigate the feasibility of using a high absorption, 257 nm femtosecond laser for processing glass substrates. The goal is to minimize damage and eliminate the need for post-processing, and ensuring superior quality and cross-sectional features. The analysis focuses on the influence of energy density and laser beam overlap ratio on processing variations. Point, line, and area processing were conducted within the achievable energy density range of 2.4–10.8 J/cm. The results indicate that as the overlap ratio increases, processing depth, influenced by heat accumulation, exhibits a non-linear growth pattern. Moreover, the phenomenon of excessive processing width, surpassing design specifications, is mitigated by utilizing burst pulses that induce heat accumulation of ultra-short pulse lasers, thereby promoting increased processing depth while restraining width expansion. By comparing the outcomes of glass substrate processing using different laser wavelengths and pulse durations, it is confirmed that employing a 257 nm femtosecond laser minimizes damage, cracks, and chipping in the processed areas, obviating the need for post-processing. This paper presents the pioneering research on glass processing using deep ultraviolet femtosecond lasers. Results indicate that clear glass ablation is achieved without cracks.