Scatterometry solutions and vision for advanced lithography process control

Abstract

Scatterometry has been presented as a solution for next generation Critical Dimension (CD) metrology for advanced lithography scanners [3,9-16]. Scatterometry used in Integrated Metrology (IM) is an entirely different technique for measuring CD data than the previous CD SEM (Scanning Electron Microscope) method and has benefits beyond those of the CD SEM including: 1) faster process time, 2) direct integration with the lithography track/scanner link, and 3) additional data collection such as line profile and stack data to detect non-litho excursions. This paper will describe technical issues and implemented solutions that allows scatterometry to seamlessly replace the CD This paper focuses on the following IM spectrometry implementation aspects: Scatterometry model creation/optimization to control multiple pitch layers and unique structures using standard scatterometry features and stack properties change control. Sample plan optimization methodology for extended scanner and track characterization, and excursion prevention (EP), from additional real-time feedback capabilities, such as: 1) within-field variation, 2) within-wafer and wafer-to- wafer variation data, 3) scan direction delta, 4) scan uniformity, 5) resist thickness uniformity, and 6) track modules health. Automation system optimization for scatterometry IM extended data and new capabilities as EP and Advanced Process Control (APC). Scatterometry vision for Litho Process Control optimization by combining scatterometry overlay and critical dimension measurement capabilities in one integrated metrology solution for the Litho track/scanner link. For the newer, faster and more expensive 193nm (and beyond) Litho links, integrated metrology is the way to ensure the link is producing quality material with high utilization. Scanner/track performance is monitored continuously and includes previously unavailable field/wafer/track module data. Automatic Process Control is improved due to fast and extended feedback, and excursions are detected immediately. Scatterometry as a methodology enables new opportunities for further process improvement when overlay and critical dimension measurement capabilities are combined in the same tool, integrated with the Litho link.