High-fidelity chip delayering using green (515 nm) femtosecond lasers

Abstract

Abstract Accurately reconstructing the metal layers of semiconductor chips is essential for legacy hardware support, design validation, and failure analysis. Conventional methods such as mechanical polishing, chemical etching, and focused ion beam (FIB) delayering, while established, tend to be slow, inconsistent, and resource-intensive—making them less suitable for systematic or scalable workflows. To address these limitations, we developed a streamlined approach combining laser-based delayering with high-resolution multimodality microscopy, offering a more efficient and reproducible alternative. Building on our earlier work with infrared laser delayering, which faces challenges related to selective material interactions and uneven ablation, in this work, we have investigated the use of a green (515 nm) laser. This alternative wavelength offers reduced sensitivity to material variations, allowing for more uniform and controlled removal of chip layers. Through a thorough parameter space exploration and optimization process, we achieved significantly cleaner delayering and exposure of underlying structures. The effectiveness of this method is demonstrated through comparative imaging using confocal microscopy and SEM, as well as material analysis via EDS, all showing notable significant improvements in layer clarity and debris reduction. These results highlight the green laser’s potential as a powerful tool for high-fidelity chip analysis in modern diagnostics and reverse engineering workflows.