Paper Effect of Temperature on the Reaction Products of Silicon in Fluorine-Based Plasmas

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.