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

Article abstract of DOI:10.1021/jp993278q

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 eY 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 SiQ₂⁺ 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⁺ suggests a different mechanism than that for Si and SiCl. For SiCl₂, formation models based on thermal heating or reaction and desorption of neutral species at chemically active surface sites, which are ruled out for Si and SiCl, should be considered.