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1 October 2013 Improving inspectability of sub-2x-nm node masks with complex SRAF
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Proceedings Volume 8886, 29th European Mask and Lithography Conference; 88860O (2013)
Event: 29th European Mask and Lithography Conference, 2013, Dresden, Germany
As Moore’s Law continues its relentless march toward ever smaller geometries on wafer, lithographers who had been relying on the implementation of a solution using EUV lithography are faced with increasing challenges to meet requirements for printing sub-2x nm half-pitch (HP). The available choices rely on 193 nm DUV immersion lithography, but with decreasing k1 values and thus shrinking process windows. To overcome these limitations, two techniques such as inverse lithography technology (ILT) and source mask optimization (SMO) were introduced by computational OPC scheme. From a mask inspection viewpoint, the impact of both ILT and SMO is similar – both result in photomasks that have a large quantity of sub-resolution assist features (SRAFs). These SRAFs are challenging for mask-makers to pattern with high fidelity and accuracy across a full-field mask, and thus mask inspection is challenged to maintain a high sensitivity level on primary mask features while not suffering from a high nuisance detection rate on the SRAF features. To solve this particular issue, new inspection approach was developed by using computational image calibration based wafer scanner simulation. This paper will be described the new capabilities, which analyzes the aerial image to differentiate between printing and non-printing features, and applying the appropriate sensitivity threshold. All analysis will be shown comparing results with and without the new capabilities, with an emphasis on inspectability improvements and nuisance defect reduction to improve mask cycle time.
© (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
In Yong Kang, Gisung Yoon, Jonghee Lee, Donghoon Paul Chung, Byung-Gook Kim, Chan-Uk Jeon, Gregg Inderhees, Trent Hutchinson, Wonil Cho, and Jiuk Hur "Improving inspectability of sub-2x-nm node masks with complex SRAF", Proc. SPIE 8886, 29th European Mask and Lithography Conference, 88860O (1 October 2013);


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