Toward DFM: process worthy design and OPC through verification method using MEEF, TF-MEEF, and MTT

Abstract

Design for Manufacturing (DFM) is being widely accepted as one of keywords in cutting edge lithography and OPC technologies. Although DFM seems to stem from designer's intensions to consider manufacturability and ultimately improve the yield, it must be well understood first by lithographers who have the responsibility of reliable printing for a given design on a wafer. Current lithographer's understanding of DFM can be thought of as a process worthy design, and the requirements set forth from this understanding needs to be well defined to a designer and fed forward as a necessary condition for a robust design. Provided that these rules are followed, a robust and process worthy design can be achieved as a result of such win-win feed-forward strategy.In this paper, we discuss a method on how to fully analyze a given design and determine whether it is process worthy, in other words DFM-worthy or not. Mask Error Enhancement Factor (MEEF), Through Focus MEEF (TF-MEEF) and Mean-To-Target (MTT) values for an initial tentative design provide good metrics to obtain a robust and process worthy design. Two remedies can be chosen as DFM solutions according to the aforementioned analysis results: modify the original design or manipulate the layout within a design tolerance during OPC. We will discuss on how to visualize the analyzed results for the robust and process worthy OPC with some relevant examples. In our discussions, however, we assumed that the robust model be being used for each design verification, and such a model derived with more physical parameters that correlates better to real exposure behavior. The DFM can be viewed as flattening the TF-MEEF across the design.

Design-Aware Mask Inspection

“…The MEEF values for different layers are shown in Table XII. These values are larger than previously reported data from the industry [31]- [33]. This is due to the lack of a well-optimized optical correction recipe that should include SRAF insertion and retargeting.…”