Analysis of metal-assisted chemical etching for microscale Si structures using Arrhenius method

Metal-assisted chemical etching (MACE) has emerged as a promising method for fabricating high-aspect-ratio Si microstructures without the damage or complexity associated with plasma-based etching. However, its thermal activation behavior and the role of catalyst morphology remain poorly understood, especially at the microscale. This study systematically investigated the effects of etchant temperature, metal thickness, and pattern geometry on the etching kinetics of MACE. By constructing Arrhenius plots from etch depth data, activation energies were extracted under various catalyst conditions, revealing that both metal coverage and thickness significantly influence the thermal energy barrier. Notably, an activation energy as low as 20.02 kJ mol^-1 was achieved, which is substantially lower than that of conventional wet etching (>50 kJ mol^-1), highlighting the efficiency of catalytic charge injection and transport in MACE. This quantitative analysis provides new insights into the fundamental mechanism of MACE and offers practical guidance for optimizing microscale three-dimensional Si fabrication processes.