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19 May 2008 Case study: the impact of VSB fracturing
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Proceedings Volume 7028, Photomask and Next-Generation Lithography Mask Technology XV; 70280F (2008)
Event: Photomask and NGL Mask Technology XV, 2008, Yokohama, Japan
Yield of a Variable Shaped Beam (VSB) created photomask is directly related to the quality of the fracture. The quality of a fracture is determined by three criteria: split CDs, slivers, and fracture consistency. Split CDs of figures whose widths are under the beam's shot size affect the quality due to adding an unnecessary shot registration error. Slivers, or extremely skinny shots, are harmful because they increase write time, adversely affect lithography patterning, and subsequently can cause inspection errors. Inconsistent fracturing of identical geometry compounds these issues that affect uniformity. Testmask structures devoted to grading the impact of slivers and consistency will be created, manufactured, and measured to enable statistical analysis of fracture data. These structures will be systematically designed to cover a wide range of sliver widths and feature geometries. The mean to target will be evaluated for these test structures, and from this, impact on CD linearity and CD uniformity can be judged. The effect of slivers on write time will be discussed in a more general scope. When evaluating the impact of slivers, five criteria should be investigated: sliver length, sliver width, proximity, avoidability, and location. Each of these criteria either affect lithography or write time. Determining how to define the maximum width of a sliver is fracture algorithm dependent, but this paper gives guidelines that should ease that process. The goal is to fracture identical geometry in an identical fashion, regardless of orientation or mirroring, while making the shots as large as possible and avoiding slivers; and when avoiding a sliver is impossible, trying to embed the sliver between large shots.
© (2008) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Brian Dillon and Tim Norris "Case study: the impact of VSB fracturing", Proc. SPIE 7028, Photomask and Next-Generation Lithography Mask Technology XV, 70280F (19 May 2008);

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