Studies of the effects of fluorocarbon deposition and etching on silicon and silicon dioxide etching processes using methyl trifluoride in an inductively coupled plasma reactor, and the development of a reactive ion beam system for the study of plasma-surface interaction mechanisms.

摘要

Plasma etching of silicon and silicon dioxide using CHF3 in an Inductively Coupled Plasma (ICP) tool, has been studied in detail. Fluorocarbon deposition on these material surfaces during processing is shown to regulate the etching process. XPS analysis of surface residues on etched silicon dioxide shows that for low bias powers, oxide etching takes place within the presence of a steady state fluorocarbon film with a thickness of less than one nanometer. This film suppresses the oxide etch rate, by interfering with the direct interaction between ion species and the oxide substrate.; Surface analysis of deposited fluorocarbon films has shown that the film stoichiometry is a result of a complex combination of several processing parameters. The ion energy flux reduces the fluorination of these films, while the stoichiometry of the reactive neutral component of the plasma primarily determines the stoichiometry of passively deposited (unbiased) films. The fluorocarbon over layer thickness on silicon during silicon etching, is shown to be directly linked to the passively deposited fluorocarbon etch yield which in turn is directly related to the film stoichiometry. A direct correlation is found to exist between the silicon etch yield and the passively deposited fluorocarbon etch yield. Thus, the silicon etch process is observed to be regulated by the deposition and etch behavior of the fluorocarbon film.; The selectivity of oxide over silicon exhibits high selectivity ratios for all pressure conditions at high inductive power. The highest selectivity of 34 has been achieved for an intermediate pressure of 10 mTorr. A suggested mechanism has been presented involving a complex tradeoff between film stoichiometry and ion enhanced diffusion of fluorine through the fluorocarbon over layer.; Finally, a reactive ion beam system is presented as a future tool for the investigation of plasma-surface interactions. The development of an ion beam source capable of producing mass selected reactive ion species is outlined including preliminary results of ion beam characterization and ion sputter yields for Ar+ incident on silicon dioxide. A technique for accurate etch yield measurements is presented involving the use of a quartz crystal microbalance as the sample substrate.