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)-and platinum (Pt)-particle-assisted etching causes 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 2 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.

Metal-Assisted Etching of n-Type and p-Type Silicon Using Patterned Platinum Films: Spatial Distribution of Mesoporous Layer and Open Circuit Potential of Silicon

“…Previously, we studied the metal-assisted etching using Pt particles as the catalysts and measured the potential of Si during etching. 21,22,48 For example, the potentials of Pt-particle-deposited n-Si and p-Si were −0.25 V 48 and 0.07 V 21 vs Ag/AgCl, respectively. The potentials of Pt-filmdeposited n-Si (after the potential drop) and p-Si are similar to that of Pt-particle-deposited n-Si and p-Si, respectively.…”

“…An electrochemical cell used for this study was illustrated in the previous paper. 48 As a working electrode, the Pt-deposited Si or bare Si was used. A rubber packing was inserted between the cell and Si.…”

Composite Porous Structure Formation by Platinum-Particle-Assisted Etching of a Highly-Doped p-Type Silicon: Evaluation of Charge Flow in Silicon

“…An electrochemical cell was illustrated in the previous paper. 31 As a working electrode, the Ptdeposited Si or bare Si was used. A rubber packing was inserted between the cell and Si.…”

“…We demonstrated that the general corrosion occurs due to the dissolution of mesoporous layer by reproducing the mesoporous layer formed during the Pt-particleassisted etching by photoelectrochemical etching of bare Si and immersing it in the etching solution. 31 Mesoporous layer formation during the metal-assisted etching has been discussed from various points of view. 7,11,[14][15][16][27][28][29][30][31][32][33] As an innovative approach, Torralba et al 29 utilized a device simulator to calculate the band bending in Si during the Pt-particle-assisted etching, aiming at the control of cone-shaped pores.…”

“…31 Mesoporous layer formation during the metal-assisted etching has been discussed from various points of view. 7,11,[14][15][16][27][28][29][30][31][32][33] As an innovative approach, Torralba et al 29 utilized a device simulator to calculate the band bending in Si during the Pt-particle-assisted etching, aiming at the control of cone-shaped pores. They discussed the mechanism of etching on the basis of the simulation results.…”