20 May 2006 EUV mask pattern defect printability
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Proceedings Volume 6283, Photomask and Next-Generation Lithography Mask Technology XIII; 62830K (2006); doi: 10.1117/12.681844
Event: Photomask and Next Generation Lithography Mask Technology XIII, 2006, Yokohama, Japan
Abstract
Mask defect specifications not only are needed to ensure quality masks for acceptable resist patterning on wafers, but also are utilized as a common goal for tool development, noticeably for mask inspection and repair. Defect specifications are generally determined by the allowable critical dimension (CD) changes from 'defect printability' experiments where a programmed defect mask (PDM) with intentionally placed defects is exposed in a stepper and the changes in resist CDs are measured. With the recent availability of extreme ultra-violet micro-exposure tools (EUV MET), a small field stepper with a numerical aperture (NA) of 0.3, 5X reduction and adjustable degrees of coherence, we are able for the first time to perform extensive studies of pattern defect printability for EUV masks with a high NA exposure tool. Such studies have investigated the defect impact to feature CDs for three different types of patterns: poly gate layer, contacts, and dense lines and spaces. This paper presents the experimental results and analysis of printability data collected under two illumination conditions, annular and dipole, on the MET with full focus and dose matrix (FEM). We have investigated as many as 10 types of defects designed on the PDM for each pattern layer. For each type of defect, a total of 15 sizes are coded on the PDM. With the consideration of limited resolution and line edge roughness of current EUV resists commonly used for EUV lithography development, the CDs under study were chosen in the range of about 40nm to 70nm. Extrapolations from these data are made to predict pattern defect specifications for smaller resist line features. Resist resolution is the main reason for the discrepancies between aerial image simulations and data presented in this paper.
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Ted Liang, Guojing Zhang, Patrick Naulleau, Alan Myers, Seh-Jin Park, Alan Stivers, Gilroy Vandentop, "EUV mask pattern defect printability", Proc. SPIE 6283, Photomask and Next-Generation Lithography Mask Technology XIII, 62830K (20 May 2006); doi: 10.1117/12.681844; https://doi.org/10.1117/12.681844
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KEYWORDS
Photomasks

Extreme ultraviolet

Extreme ultraviolet lithography

Inspection

Scanning electron microscopy

Printing

Cadmium

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