Date of Award

1993

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Abstract

The effects of low energy reactive ion bombardment of semiconducting silicon material have been investigated by X-ray photoelectron spectroscopy. The residual surface damage induced by a conventional fluorocarbon plasma reactive ion etching of silicon consisted of a uniform fluorocarbon deposited film approximately 4nm in thickness which covered a silicon compound reaction layer. This reaction layer was comprised of silicon oxides, carbide and fluorosilyl species distributed in depth to approximately 2nm. The removal of the residuel surface damage was accomplished by an ozone oxidation plus a wet oxide chemical etching step processing and monitored by surface charge spectroscopy. This residual surface damage to silicon was simulated by mass-filtered reactive F{dollar}\sp+{dollar}, and CF{dollar}\sp+{dollar} ion beam bombardment of silicon at normal incidence and room temperature. In addition, the effects of Cl{dollar}\sp+{dollar} ion beam bombardment of silicon were studied in order to provide fundamental information on the chlorine plasma dry etching. The ion kinetic energy range of interest was 1eV to 100eV for ion doses between {dollar}3\times 10\sp{lcub}14{rcub}{dollar} and {dollar}1\times 10\sp{lcub}18{rcub}{dollar}/cm{dollar}\sp2{dollar}. The residual surface damage to the silicon was seen as surface incorporation of the reactive ion species in the form of a fluorosilyl species layer for F{dollar}\sp+{dollar} bombardment, a fluorocarbon deposited layer and a silicon carbide/fluorosilyl layer for CF{dollar}\sp+{dollar} bombardment, and finally, surface oxidation and subsequent sputtering of the oxygenated species by Cl{dollar}\sp+{dollar} bombardment. The surface species of SiX{dollar}\sb{lcub}\rm n{rcub}{dollar} with X = F or Cl, and for n ranging from 1 to 4 were different for the two halogen ions investigated. For Cl{dollar}\sp+{dollar} bombardment, n was less than 2 for the ion energy range of 1 to 100eV, while for F{dollar}\sp+{dollar} ions, n included 1 to 4. Distinct surface reaction products were consistent with the reactivity of the specific ion/silicon systems.

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