Overlay characterization and matching of immersion photoclusters

Abstract

Many factors are driving a significant tightening of the overlay budget for advanced technology nodes, e.g. 6nm [mean + 3σ] for 22nm node. Exposure tools will be challenged to support this goal, even with tool dedication. However, tool dedication has adverse impact on cycle time reduction, line productivity and cost issues. There is a strong desire to have tool to tool (and chuck to chuck) matching performance, which supports the tight overlay budgets without tool dedication. In this paper we report improvements in overlay metrology test methods and analysis methods which support the needed exposure tool overlay capability. © 2010 SPIE.