DFM for maskmaking: design-aware flexible mask-defect analysis

Abstract

We present a novel software system that combines design intent as known by EDA designers with defect inspection results from the maskshop to analyze the severity of defects on photomasks. The software -named Takumi DesignDriven Defect Analyzer (TK-D3A)-analyzes defects by combining actions in the image domain with actions in the design domain and outputs amongst others flexible mask-repair decisions in production formats used by the maskshop. Furthermore, TK-D3A outputs clips of layout (GDS/OASIS) that can be viewed with its graphical user interface for easy review of the defects and associated repair decisions. As inputs the system uses reticle defect-inspection data (text and images) and the respective multi-layer design layouts with the definitions of criticalities.The system does not require confidential design data from IDM, Fabless Design House, or Foundry to be sent to the maskshop and it also has minimal impact on the maskshop's mode of operation. The output of TK-D3A is designed to realize value to the maskshop and its customers in the forms of: 1) improved yield, 2) reduction of delivery times of masks to customers, and 3) enhanced utilization of the maskshop's installed tool base.The system was qualified together with a major IDM on a large set of production reticles in the 90 and beyond-65 nm technology nodes of which results will be presented that show the benefits for maskmaking. The accuracy in detecting defects is extremely high. We show the system's capability to analyze defects well below the pixel resolution of all inspection tools used, as well as the capability to extract multiple types of transmission defects. All of these defects are analyzed design-criticality-aware by TK-D3A, resulting in a large fraction of defects that do not need to be repaired because they are located in non-critical or less-critical parts of the layout, or, more importantly, turn out to be repairable or negligible despite of originally being classified as unrepairable when no such criticality knowledge is used. Finally, we show that the runtimes of TK-D3A are relatively short, despite the fact that the system operates on full-chip designs.

European MEDEA+ CRYSTAL project: DFM photomasks inputs for EDA workflow task force

“…In short, through several discussions with EDA providers (Mentor Graphics, Cadence, Synopsys, Xyalis...) private discussions with professionals in recent symposiums (Date07 in Nice, Medea+ DAC in Grenoble, and Stresa in Italy), and Mask/Lithography recent symposiums we may conclude that there is no existing comprehensive Photomask DFM flow in place, even if some partial Photomask DFM approaches have already been studied [9] [10].…”