Ion-beam nano-smoothing of sapphire and silicon carbide surfaces

D. B. Fenner, V. DiFilippo, T. G. Tetreault, J. K. Hirvonen, L. C. Feldman

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


Significant reductions in the surface roughness of single-crystal wafers of sapphire and silicon carbide with microelectronic-grade high polish were observed when exposed to a gas-cluster ion beam (GCIB). Atomic-force microscopy revealed that the typical initial surfaces consisted of a fine but small, random roughness together with relatively large and sharp asperities. The latter were removed efficiently by GCIB. Smoothing process improvements are also reported. The SiC wafers have a high density of shallow scratch marks and these too were removed, with the average roughness Ra falling below 4 Å after the best process. Analysis of the SiC by Rutherford backscattering spectroscopy in channeling mode revealed that when the GCIB process was adjusted so that asperities and scratch marks were removed, there was no increase in near- and at-surface damage. In particular, no lattice damage was observed of the sort typically caused by ion implantation prior to annealing. Significantly, it was found that oxygen gas cluster ion beams provided superior results with SiC as compared with argon GCIB. Surface smoothing mechanisms are proposed to explain these results.

Original languageEnglish
Pages (from-to)17-24
Number of pages8
JournalProceedings of SPIE - The International Society for Optical Engineering
Publication statusPublished - Jan 1 2001


  • Atomic force microscope
  • Channeling
  • Damage
  • Gas-cluster ion beam
  • Rutherford backscatter
  • Sapphire
  • Silicon carbide
  • Surface roughness

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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