EUV resists, while improving steadily, generate a number of nanobridge or break defects that increases quickly as the pitch approaches 30 nm. Inline inspection methods are therefore needed to reliably detect patterning defects smaller than 20 nm. Massive e-beam metrology provides the high resolution needed to measure these defects, while remaining compatible with HVM throughput requirements. In this work, we used a direct metal (Ru) etch process, to fabricate EUV-patterned electrical structures in the 32 nm-36 nm pitch range. We demonstrate an almost one-to-one correspondence between the e-beam metrology yield of the structures, and their electrical yield. The e-beam inspection is realized with a large-field-of-view HMI eP5 e-beam system. The match between e-beam and electrical yield shows that our e-beam inspection is able to catch all electrically relevant line breaks, while excluding false flags. These results demonstrate the capability of massive e-beam inspection in predicting electrical yield.
Extreme ultraviolet (EUV) lithography is the technology for high volume manufacturing (HVM) of semiconductor ICs for photoresist patterns smaller than 75nm pitch¹. A persistent challenge of the EUV scanner is to supply a high contrast image with enough photons to the photoresist (PR) to meet HVM productivity targets with acceptable dimensional and defectivity control. Local stochastic variability in dimension and placement dominates the total dimension control budget and reducing that variability by increasing the exposure dose comes at the cost of scanner throughput. Our objective is to deliver holistic patterning solutions by co-optimization of patterning film stack, lithography, and subsequent etch processes to transfer the patterns to the target layer with CD and placement control of order 1nm or less! This synergistic approach enables circuit fabrication customers to manage the tradeoff between stochastic defects and productivity in EUV patterning.
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