In the semiconductor industry, dies singulation is a critical step, as poor dicing leads to yield loss. Although, mechanical sawing remains the most widely used technique, it becomes inefficient for thicker wafers and induces numerous defects along the cut edges.

Laser stealth dicing (SD) has emerged as a promising solution for the singulation of advanced semiconductor packages; however, current industrial implementations mainly rely on 1–2 µm infrared sources. At these wavelengths, linear absorption limits the penetration in thick silicon wafers.

In this work, we investigate the potential of an innovative 2.8 µm nanosecond laser for SD of thick silicon wafers. By exploiting three-photon absorption to induce subsurface modified layers in a true single-shot regime, where one laser pulse generates one modification. Experiments are performed on boron-doped <100> silicon wafers of 650 µm thickness using a Nano2800 (Femtum, Québec) mid-infrared source. The laser power, feed rate and number of pulses are independently varied to analyze the evolution of modified layer length, spacing, and morphology. The results demonstrate that longer-wavelength irradiation enables the formation of deeper, high-aspect-ratio modified layers using a single pulse, while maintaining feed rates compatible with industrial requirements. Complete wafer singulation is achieved with only three modified layers. Furthermore, we demonstrate that the modified layer length is fundamentally limited by the Rayleigh length of the focused beam, offering a tunable process that can be adapted to both thinner and thicker wafers. These findings highlight the potential of 2.8 µm nanosecond lasers for robust, single-shot SD of silicon wafers.