Ion-Enhanced Etching of Si(100) with Molecular Chlorine: Neutral and Ionic Product Yields as a Function of Ion Kinetic Energy and Molecular Chlorine Flux

Abstract

Time-of-flight mass spectrometry (TOFMS) is used to measure neutral and ionic silicon etch products evolved during argon ion-enhanced etching of room temperature Si(100) with molecular chlorine. The yields of these neutral and ionic etch products are examined as a function of ion energy, ion flux, and molecular chlorine flux. For the neutral products, an Ar+ ion energy range of 275−975 eV is used, while the ionic product measurements are continued down to 60 eV. The atomic Si, SiCl, and SiCl2 neutral etch products are measured without complications due to fragmentation by using 118-nm laser single-photon TOFMS. Atomic Si and SiCl are the major observed etch products. The ionic Si+ and SiCl+ etch products are also measured using TOFMS; however, the SiCl2+ species is not observed. The similarities between neutral and ionic Si and SiCl etch products as a function of various parameters suggest a model based on direct collisional desorption. For the observed neutral SiCl2 product, the absence of SiCl2+ suggest...