Synergistic Post-Processing of Micro-through-Slot Sidewalls in Si Wafers via Hybrid Laser-Electrochemical-Abrasive Method: Mechanism Investigation and Process Simulation

Silicon (Si) wafer-based microfabrication is essential for applications such as integrated circuits, photovoltaics, and MEMS. Among these applications, micro-through-slots (MTS) represent a critical class of through-microstructures and require advanced processing techniques. This study introduces a novel self-coordinated method integrating laser irradiation, electrochemical corrosion (ECC), and abrasive erosion for efficient and eco-friendly MTS sidewall post-processing. Pulsed laser irradiation selectively enhances Si conductivity, facilitating localized ECC, while laser-induced breakdown generates cavitation effects that propel micro-abrasive particles, disrupting the passivation layer. This synergistic interaction is sustained under intensive laser exposure. The study first examines the individual and combined effects of laser irradiation, ECC, and low-speed abrasive jet erosion on surface morphology of Si wafer. Results indicate that the most significant surface modification occurs under the synergy of all three factors at the given low laser power density and abrasive velocity. Afterwards, systematic experiments were conducted to analyze the influences of key processing parameters on the MTS sidewall quality after post-processing. Optimal processing conditions of an external voltage 40 V, a laser single-pulse energy 1 mJ, and a processing time 10 min yield a significant reduction in MTS sidewall roughness to 320 nm. Additionally, a COMSOL-based thermal-electrical field model simulates temperature and current density distributions, revealing that increasing laser pulse energy from 0.2 mJ to 1 mJ raises maximum sidewall temperature by 28 % and enhances current density by three orders of magnitude, confirming the synergistic effect of laser irradiation and ECC.