Laser-induced chemical etching of silicon in chlorine atmosphere

Abstract

Laser-induced chemical etching of (100) Si in Cl₂ atmosphere has been investigated using a combined laser-beam irradiation scheme. 308 nm XeCl excimer laser radiation at parallel incidence has been used to exclusively generate Cl atoms in the gas phase above the Si surface. Additionally, 647.1 nm Kr⁺ laser radiation at perpendicular incidence has been used to exclusively generate photocarriers within the Si surface. The Cl atom concentration was determined — independently — from both the observed chemiluminescence following the Cl-Cl atom recombination, and from numerical calculations. The etch rateW observed on the Si surface was found to be directly proportional to the Cl atom concentration in the gas phase, and it increases sublinearly with the Kr⁺ laser powerP according toW∞P ^0.7.