Laser stealth dicing technology for carbon nanotubes wafer

With the rapid advancement of advanced packaging and heterogeneous integration technologies, wafer-level material dicing faces increasingly stringent requirements in terms of precision, efficiency, and material integrity. Prior to subsequent processes such as bonding and packaging, high-quality and low-damage dicing must be performed to ensure the structural stability and reliability of chips. As a novel one-dimensional nanomaterial substrate, carbon nanotube (CNT) wafers exhibit excellent thermal conductivity, high mechanical strength, and a wide bandgap, offering broad application prospects in optoelectronic devices and thermal management chips. However, due to their inherent brittleness, susceptibility to microcracks, and expanded heat-affected zones during processing, conventional mechanical or surface laser dicing methods struggle to meet the demands of high-quality cutting. Laser stealth dicing (LSD) technology, with its advantages of non-contact processing, high selectivity in energy deposition, and subsurface energy focusing, has emerged as a promising approach for achieving damage-free cutting of CNT wafers. In this study, a directional CNT thin-film layer was constructed on the surface of silicon (Si) wafers, and SD experiments were conducted using nanosecond lasers. The effects of key process parameters - such as laser energy and SD speed - on cutting path stability and cross-sectional quality were investigated. Characterization techniques, including scanning electron microscopy (SEM), Raman spectroscopy, and 3D laser scanning confocal microscope (LSCM), were employed to quantitatively analyze the structural changes, heat-affected zone width, and material integrity in the stealth cutting region. Experimental results demonstrate that, under optimized processing conditions, CNT wafers achieve significant crack suppression, smooth cross-sections, and well-confined heat-affected zones.