Formation and Dissolution of Mesoporous Layer during Metal-Particle-Assisted Etching of n-Type Silicon

Abstract

Metal-assisted etching has attracted increasing attention as a method to produce porous silicon (Si). We previously found that gold (Au)-particle-assisted etching and platinum (Pt)-particle-assisted etching cause general corrosion of the Si substrate, but not in the case of silver (Ag)-particle-assisted etching [A. Matsumoto, et al., RSC Adv., 10, 253 (2020)]. In this work, we discussed the mechanism of the general corrosion with electrochemical approaches. We demonstrated that potentials of the Au- and Pt-deposited Si during the metal-particle-assisted etching are higher than that of the bare Si in the etchant, but not in the case of the Ag-deposited Si. We also performed electrochemical etching of the bare Si by applying the potential during the Pt-particle-assisted etching, resulting in the formation of a mesoporous layer which was dissolved in the etchant. We concluded that the general corrosion occurs during the metal-particle-assisted etching due to the dissolution of the mesoporous layer formed by anodic polarization of the Si substrate.

Keywords

• metal-assisted chemical etching
• porous silicon
• anodic polarization
• general corrosion