Characteristics of etching residues on the upper sidewall after anisotropic plasma etching of silicon

Abstract

Anisotropic Si nano-trench structures were fabricated using inductively coupled HBr + Cl2 plasmas for sidewall etching residue analysis. The sidewall etching residues formed inside the Si nano-trench patterns were analyzed via tilted X-ray photoelectron spectroscopy. The changes in the chemical composition and binding state of the etching residues formed on the Si nano-trench sidewalls were investigated with various gas mixing ratios in HBr + Cl2 plasma etching processes. The sidewall chemistry of the plasma-etched Si nano-trench patterns was examined at various take-off angles. SiO2 and suboxide groups (SixOy, x ≤ 2, y ≤ 3) were formed on the Si nano-trench sidewalls after the plasma etching. An increase in the chlorine content of the gas plasma resulted in the increased formation of SiO2 and suboxide residual groups on the Si nano-trench sidewalls. Additionally, the changes in the chemical states of the Si nano-trench sidewalls after a wet-cleaning process were examined using our designed experimental technique.