you should remove CR layer with CR MASK etchant.

  CR layer instantly oxidizes for several nanometer thick as soon as it exposed
to the air.

  So, you should use CR Mask etchant.

  Good luck!!

  Sokwon

Ho Yin Chan  wrote:
  Hi all,

Currently, I am etching PECVD oxide using standard RIE and Cr is the
masking layer. However, I found that I cannot remove the Cr mask using
Cr etch after going through the RIE process. I am wondering if there
is anything happened on the Cr surface. I'd like to see if you could
give me some suggestions on how to remove the top Cr layer. Thanks

HY