A new reticle inspection system with three parallel scanning laser beams for UV imaging for both contamination and pattern inspection has been developed to detect defects on advanced reticles for DUV steppers and low k1 lithography for .13 mm and extensions to .10 mm design rules. The development of the new three beam architecture at UV wavelength has significantly increased system throughput while improving the resolution of the imaging optics for inspecting advanced reticles including Attenuating, Tri-Tone, and Alternating PSM's and reticles with aggressive OPC. The system is capable of running multiple inspection algorithms simultaneously in transmitted and reflected light to achieve concurrent pattern and STARlightTM inspection, thus improving both sensitivity and inspection thoroughness with a single inspection. These improvements enable fast inspections of reticles for 4X lithography design rules at 0.18 mm, 0.15 mm and 0.13 mm.
Initial simulations were performed to optimize performance of optical components and a new defect detection algorithm. The simulations identified that with the optics changes to achieve three beam scans and with new algorithms, the inspection was more sensitive to all defect types including on edge contamination defects, which can be particularly difficult to detect. Using both PSL and programmed defect test masks and real production reticles, initial observations of the nature and the frequency of defects detected with this 100nm sensitivity instrument will be presented.
With more defects to review, the system software provides concurrent or remote defect review so time to
disposition defects does not effect system inspection capacity. With smaller defects to review the quality of defect review images has a direct impact on the effectiveness and ease-of-use of reticle inspections systems. The smaller review pixel with the system combined with a suite of review imaging tools, yields high quality images for defect dispositioning.