Low temperature wet etching to reveal sub-surface damage in sapphire substrates

Purushottam Kumar, Jinhyung Lee, Gwangwon Lee, Suhas Rao, Deepika Singh, Rajiv K. Singh

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


Low temperature wet etching using various etchants was investigated to reveal sub-surface damage in sapphire wafer induced during lapping. Surface scratches during wafer preparation is conveniently observed using optical or atomic force microscopy whereas sub-surface damage to crystal requires techniques such as X-ray diffraction, Raman spectroscopy etc. In this study, sub-surface damage in sapphire was revealed as shallow scratches by etching in H 2 SO 4 at temperatures ∼125 °C and 3:1 H 2 SO 4 -H 3 PO 4 at temperatures ∼75 °C. These etching conditions showed no measurable etch rate of sapphire and also did not affect the pristine sapphire surface. The heavily damaged and sub-surface damaged layer was determined to be 1.6 ± 0.1 and 2.2 ± 0.1 μm deep by repeated chemical mechanical polishing and etching of sapphire wafer lapped with 1 μm diamond abrasive.

Original languageEnglish
Pages (from-to)58-61
Number of pages4
JournalApplied Surface Science
StatePublished - 15 May 2013
Externally publishedYes


  • Sapphire
  • Sub-surface damage
  • Wet etching


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