Litho-friendly Design (LfD) Methodologies Applied to Library Cells

摘要

During the last years, various DfM (Design for Manufacturability) concepts have been proposed and discussed. Resolution enhancement technologies with the goal to provide reasonable printability over the whole lithographic process window, and the optimization of these tools and processes by print image simulation (PW-ORC) have become crucial aspects of DfM today. In addition, designers and layouters will become increasingly involved in yield discussions, as they will get tools and methods to identify and remove yield issues in the drawn layout. Such a lithography-aware design data flow, which is called LfD (Litho-friendly Design), is a very important step towards a fully developed DFM environment.Recently, the leading EDA tool vendors have provided tools for efficient process window analysis and a scoring of lithography issues in a form, which is close to productive usability. We report in this paper the implementation of LfD into the design flow of library cells for the 90 nm and the 65 nm design rule technologies. Specific aspects of such a LfD flow, like the availability of robust process models in early development stages are discussed as well as appropriate means to assess the results.