Provided is a method for creating a mask blank that include a stop layer. The stop layer is optically compatible and process compatible with other layers included as part of the mask blanks. Such blanks may include EUV, phase-shifting, or OMOG masks. The stop layer includes molybdenum, silicon, and nitride in a proportion that allows for compatibility and aids in detection by a residual gas analyzer. Provided is also a method for the patterning of mask blanks with a stop layer, particularly the method for removing semi-transparent residue defects that may occur due to problems in prior mask creation steps. The method involves the detect of included materials with a residual gas analyzer. Provided is also a mask blank structure which incorporates the compatible stop layer.