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

Area of Science:

• Materials Science
• Nanotechnology
• Surface Chemistry

Background:

• Metal-assisted chemical etching (MACE) is a damage-free technique for creating high-aspect-ratio silicon microstructures.
• Understanding MACE's thermal activation and catalyst morphology is crucial for microfabrication but remains limited.

Purpose of the Study:

• To systematically investigate how etchant temperature, metal thickness, and pattern geometry influence MACE etching kinetics.
• To quantify the activation energy of MACE under varying catalyst conditions.

Main Methods:

• Fabrication of silicon microstructures using MACE.
• Systematic variation of etchant temperature, metal thickness, and pattern geometry.
• Analysis of etch depth data using Arrhenius plots to determine activation energies.

Main Results:

• Etchant temperature, metal thickness, and pattern geometry significantly affect MACE etching kinetics.
• Activation energy was found to be strongly dependent on metal coverage and thickness.
• Achieved a remarkably low activation energy of 20.02 kJ mol^-1, significantly lower than conventional wet etching.

Conclusions:

• MACE exhibits significantly lower activation energy compared to conventional wet etching, demonstrating its efficiency.
• Catalyst morphology and thickness play a critical role in the thermal energy barrier of MACE.
• Provides quantitative insights into MACE mechanisms and practical guidance for optimizing 3D silicon microfabrication.