In mask fabrication pattern-inspection is a key step. It ensures mask quality is being met according to the customer defect criteria. Tool selection is based on a comparison between customer requirements and tool capabilities. Inspection tools are typically specified by a minimum feature size at which a certain minimum defect size can be achieved. Mask shops on the contrary manufacture masks for a wide range of feature and defect sizes. As a consequence detailed tool characterizations are needed, which go beyond the typical tool specifications. In this paper characterization results for three KLA 576 inspection systems are presented. Defect sensitivity was studied for the pixels named P125 and P90 in combination with the so-called die-to-die (D2D) and die-to-database (D2Db) algorithms using standardized programmed defect masks. The good correlation of the qualification data made modeling of the tool behavior possible. The modeling parameters were used to compare tool-to-tool and plate-to-plate variations as well as specified and actual tool performance. For a variety of mask types, such as Chrome-on-Glass (COG) masks, embedded phase shift masks at a lithography wavelength of 193 nm (EPSM-193), and extreme ultra-violet (EUV) masks, the optical contrast was studied over a wide range of feature sizes. From the resultant data material dependence and image contrast below the minimum feature size was evaluated.

Date Published: 9 November 2005
PDF: 10 pages
Proc. SPIE 5992, 25th Annual BACUS Symposium on Photomask Technology, 599246 (9 November 2005); doi: 10.1117/12.637782

Published in SPIE Proceedings Vol. 5992:
25th Annual BACUS Symposium on Photomask Technology
J. Tracy Weed; Patrick M. Martin, Editor(s)