Hi,
  I want to remove a thin layer of SiO2 (200 nm)  from my sapphire wafer. I
tried using HF but it etches sapphire as well. Can anyone suggest me what
chemical do I use to remove oxide but not sapphire.
  Thanks,

  Nitin Shukla
  PhD Candidate
  Nanoscale Energy Transport Laboratory
  Department of Mechanical Engineering
  Virginia Tech
  Blacksburg, VA 24061
  Tel No: 540-231-5579