关键词：带宽限制；纳米波长；函数
摘 要：In this work, we used a high accuracy synchrotron-based reflectometer to experimentally determine the effects of angular bandwidth limitations on high- NA EUV mask performance. We collected the scatterometry data of both the mask blank and absorber field, as well as mask pattern diffraction performance as a function of illumination angle, scatter angle, and wavelength. Gratings down to 44 nm half pitch on mask, up to 16° angle of incidence (AOI), and wavelength ranging from 13.3 to 13.7 nm were considered. Rigorous Coupled- Wave Analysis (RCWA) was used to model scatterometry results which were compared with measurement. The experimental measurements on a mask with a multilayer reflectivity of over 60% at 13.5 nm wavelength that peaked about 10° showed that computing the large area reflectivity as a function of wavelength and incident angle from 0 to 14° resulted in root mean square errors in reflectivity unacceptably as high as 13% and 0.8% of the incident beam for the multilayer and absorber respectively. This dropped to 5% and 0.7% respectively when interdiffusion and wavelength-dependent refractive indices were taken into account. Calibration by fitting to the measured data reduced the errors to 0.8% and 0.08% respectively.