In situ spectroscopic ellipsometry studies of electron cyclotron resonance (ECR) plasma etching of oxides of silicon and GaAs

N. J. Ianno, S. Nafis, Paul G. Snyder, Blaine Johs, John A. Woollam

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

In situ spectroscopic ellipsometry (SE) covering the spectral range from 280 to 1000 nm was performed during RF bias assisted electron cyclotron resonance (ECR) etching of SiO2, GaAs oxide, silicon, and GaAs by a CCl2F2/O2 mixture. The etch rate of SiO2/Si samples as a function of RF bias power, and total pressure was then measured, in situ, for a constant ECR power of 175 W, and CCl2F2/O2 flow rate ratio of 1 3 by performing SE at selected wavelengths most sensitive to changes in SiO2 thickness. A wide range of etch parameters can be investigated without changing samples by employing a relatively thick SiO2 layer. This allows rapid optimization of the etch parameters, and can also provide accurate endpoint detection in the face of a time-dependent etch rate. Ellipsometric monitoring of bulk silicon and GaAs samples cannot provide in situ etch rates, however, insight into the etch mechanism may be gained by observing the effect of the etch process on the native oxide layer, surface roughness, and in the case of GaAs, on the surface stoichiometry.

Original languageEnglish (US)
Pages (from-to)17-21
Number of pages5
JournalApplied Surface Science
Volume63
Issue number1-4
DOIs
StatePublished - Jan 1993

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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