Silicon etch in the presence of a fluorocarbon overlayer: The role of fluorocarbon cluster ejection

Joseph J. Végh, David Humbird, David B. Graves

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Molecular dynamics (MD) simulations have been carried out to examine the role of large fluorocarbon (FC) cluster ejection during steady state Si plasma etching in the presence of a FC overlayer on the surface. Previous MD studies showed that the thickness of the FC film fluctuates during steady state Si etch, and that these fluctuations are an integral component of the Si etch mechanism. This work focuses on how the ejection of large FC clusters (containing six or more carbon atoms) contribute to FC film thickness fluctuations. Simulations reveal that ∼40%-60% of the carbon removal occurs through these clusters at steady state. Large FC cluster ejection was always observed when FC films form during etching. Product and kinetic energy distributions illustrate the effects of the plasma chemistry (i.e., the FCF Ar+ ratio impacting the surface) on the cluster ejection process. Further studies have also been carried out to examine the possibility of cluster redeposition on the surface and evaluate the likelihood of these large clusters contributing to FC film growth in typical plasma systems. Several clusters were found to have comparable (or even higher) sticking probability than the original FC deposition precursors. Overall, this work suggests that FC clusters play a key role in the Si etch process in these systems, and can also contribute to FC film growth. The effects of clusters in profile simulations and other plasma processing analyses may be more important than previously thought.

Original languageEnglish (US)
Pages (from-to)52-61
Number of pages10
JournalJournal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
Issue number1
StatePublished - 2008
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films


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