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Proceedings Paper

Mask defect disposition: flux-area measurement of edge, contact, and OPC defects correlates to wafer and enables effective decisions
Author(s): Peter Fiekowsky; Darren Taylor; David Wang; Chien-Chu Yang; Shu-Chun Lin; L. H. Tu; K. R. Lin
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Paper Abstract

Lithographers' ability to set useful defect and contact specifications has almost disappeared as chip geometries have shrunk. As features sizes have decreased, measurement error has increased to 25% of the maximum allowable defect size. This has made defect disposition so difficult that many processes now require that all detected defects be repaired because the automatic defect sizing is almost meaningless, that is, the required guard band is nearly the size of the defect specification (Reynolds, BACUS 2000). Many mask processes have abandoned defect sizingin favor of stepper simulation, either using simulation microscope, such as AIMS, or software, such as NTI's VSS. However, AVI's optical Flux-Area measurement technique provides accuracy and repeatability that gives the simple, time tested defect specification technique new life. This study demonstrates high quality edge-, contact-, and OPC- defect disposition can be achieved using the Flux-Area technique. A test mask with a range of edge defects as well as mis-sized contacts and OPC defects was written. The mask defect sizing performed with the AVI is shown to be consistent on different chips using the same process. Thus it is shown that all the over-spec defects on the wafer were measured as over-spec on the mask. Results show that edge defect size on the wafer can be accurately predicted from the AVI defect area; that printed contact size is linearly proportional to the AVI measured area, on both square and irregular contacts; and that OPC defects (printed line-end separation errors) can be accurately predicted from AVI serif-area measurements on the mask. With the Flux-Area measurement technique as implemented on the AVI Photomask Metrology System, defects can be measured with long term repeatability and rms repeatability between machines of better than 10nm, 3% of a 0.3micrometers defect. This means that guard bands can often be reduced from 0.15micrometers to below 0.05micrometers .

Paper Details

Date Published: 5 September 2001
PDF: 8 pages
Proc. SPIE 4409, Photomask and Next-Generation Lithography Mask Technology VIII, (5 September 2001); doi: 10.1117/12.438329
Show Author Affiliations
Peter Fiekowsky, Automated Visual Inspection (United States)
Darren Taylor, Photronics, Inc. (United States)
David Wang, Precision Semiconductor Mask Corp. (Singapore)
Chien-Chu Yang, Precision Semiconductor Mask Corp. (Taiwan)
Shu-Chun Lin, Precision Semiconductor Mask Corp. (Taiwan)
L. H. Tu, United Microelectronics Corp. (Taiwan)
K. R. Lin, United Microelectronics Corp. (Taiwan)

Published in SPIE Proceedings Vol. 4409:
Photomask and Next-Generation Lithography Mask Technology VIII
Hiroichi Kawahira, Editor(s)

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