At-wavelength inspection of EUVL mask defects with a 1X Offner ring-field system

Abstract

At-wavelength inspection of EUV masks containing programmed defects was performed with an EUV 1X Offner ring-field system. At-wavelength inspection was sensitive to thin substrate defects. The sensitivity of the detection was limited by the resolution of the imaging system. At-wavelength inspection also revealed defects that are not detectable by other inspection techniques.