As the industry embarks on sub 50nm half pitch design nodes, higher resolution and advanced photomask inspection algorithm are needed to resolve shrinking features and find critical yield limiting defects. In this paper, we evaluate the detection capability of STARlight2+ 72nm pixel on sub-50nm memory masks. The mask sets targeted for this evaluation were focused on critical layers. Although memory mask sets are dominated by multi-die layout, single die layout masks were also inspected because of their significance during research and development. Inspection results demonstrated the performance of STARlight2+ based on its sensitivity to contamination defects and the inspectability of masks with this detection method. The most common plan of record for mask inspection in a wafer fab is die-to-die transmitted pattern inspection modes, which limits the inspection area to the die region only and cannot be used for single-die reticle inspections. However, STARlight2+ has single die inspection capability, which is also needed in order to inspect scribe-lines and frame areas. The primary defects of interest are photo induced crystal defects or haze. Haze continues to be the primary reason for mask returns at 193nm exposure across the industry. The objective of this paper is to demonstrate STARlight2+ 72nm capability to support memory wafer fab mask qualification requirements.

Date Published: 17 October 2008
PDF: 9 pages
Proc. SPIE 7122, Photomask Technology 2008, 71223M (17 October 2008); doi: 10.1117/12.802332

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