Conventional photomask inspection techniques utilize global sensitivity for all inspected area in the die; SRAF and OPC features become the sensitivity-limiters, which can result in reduced visibility to defects of interest (DOI). We describe the implementation of Sensitivity Control Layer (SCL), a novel database inspection methodology for the KLA-Tencor TerascanHR platform. This methodology enables inspection at maximum sensitivity in critical die-areas via "layer definition" during job set-up and sensitivity management of the layers during inspection. Memory device inspection performance was improved through the use of up to six control layers to increase sensitivity in the active area while reducing nuisance detections by as much as 100X. The corresponding inspection time was reduced by 30%, illustrating the potential for substantial throughput advantage using SCL. Post-inspection analysis and improved disposition accuracy of the SCL-enabled inspections will also benefit cycle time and higher throughput. In all test cases, sensitivity parameters were increased in the regions of interest over baseline inspections run with typical production-use methodologies. SCL inspection management and application on OPC structures, SRAFs, and MRC violations (slivers) are discussed in detail.

Date Published: 17 October 2008
PDF: 9 pages
Proc. SPIE 7122, Photomask Technology 2008, 71221G (17 October 2008); doi: 10.1117/12.801480

Published in SPIE Proceedings Vol. 7122:
Photomask Technology 2008
Hiroichi Kawahira; Larry S. Zurbrick, Editor(s)