A key aspect in understanding silicon etching mechanisms is analyzing the characteristics of volatile reaction products, whose properties, particularly stoichiometry, vary significantly with temperature and fluorine coverage. These variations influence crucial etching attributes, such as reaction kinetics and the transition from isotropic to anisotropic etching. Temperature and fluorine coverage thus emerge as the primary determinants of the stoichiometry and complexity of reaction products. At low temperatures, the Langmuir-Hinshelwood mechanism dominates, where bimolecular reactions between adsorbed species produce SiF₄ as the major product. As temperature increases, thermal desorption becomes the primary mechanism, favoring the formation of SiF₂ and SiF. Similarly, fluorine coverage influences reaction pathways: under low coverage, SiF₄ is predominant, while higher coverage leads to more complex intermediates such as Si₂F₆ and Si₃F₈ through bimolecular or trimolecular reactions involving SiF₃ and SiF₂.

Keywords: Etching mechanism, Reaction product, Temperature, Thermodynamic