A surface ir study of inorganic film formation GaAs, silicon and germanium by aqueous NH4F, and HF

V. A. Burrows, J. Yota

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13 Scopus citations

Abstract

Hydrofluoric acid buffered with ammonium fluoride (BHF) is a common cleaning-stripping solution used in silicon processing. Little is known of the surface chemistry which occurs as a result of BHF treatment. Surface IR spectroscopy in the multiple internal reflection mode was used to study silicon, germanium, and gallium arsenide surfaces treated with BHF. For each of these materials, the BHF not only dissolved the native oxide, but also deposited a film comprising ammonium salts (NH4F and NH4F·HF). These salts subsequently slowly reacted with the semi-conductor substrate to form hexafluorometallate compounds ((NH4)2SiF6, (NH4),GeF6, and (NH4)3GaF6). Although the original ammonium fluoride and bifluoride salts are quite soluble in alcohols as well as aqueous solutions, the hexafluorometallates are completely insoluble in alcohols, and can only be removed by careful water or aqueous acid rinse. The presence of these previously unsuspected films could seriously degrade electronic performance of the materials.

Original languageEnglish (US)
Pages (from-to)371-381
Number of pages11
JournalThin Solid Films
Volume193-194
Issue numberPART 1
DOIs
StatePublished - 1990

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ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry

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