Immersion defect reduction, part II: the formation mechanism and reduction of patterned defects

Abstract

193-nm immersion lithography is the only choice for the 45-nm logical node at 120-nm half pitch and extendable to 32-and 22-nm nodes. The defect problem is one of the critical issues in immersion technology. In this paper, we provided a methodology to trace the defect source from optical microscope images to its SEM counterparts after exposure. An optimized exposure routing was also proposed to reduce printing defects. The average defect count was reduced from 19.7 to 4.8 ea/wafer.

Marching of the microlithography horses: electron, ion, and photon: past, present, and future

“…Immersion lithography is run at single-digit number of defects per wafer, with overlay and yield comparable to those of dry systems in the 90-and 65-nm nodes. Researchers in many disciplines contribute to the success, amongst them: Theological analysis in the early days of immersion lithography in DOF 43 , polarized illumination 44 , image deterioration by bubbles in immersion fluid 45 , and processing parameters for multiple technology nodes 46 ; materials work to reduce defects such as switchable BARC 47 , watermark reduction 48 , and immersion hood cleaning 49 ; process analysis such as algorithm 50 to pinpoint the location of particle leakage on the immersion hood, using super-positioned defect distribution chart, and speedy defect classification 51 . Figure 14 shows a super-positioned defect distribution chart with predicted particle leakage in red and actual particles in black.…”