Proceedings Article | 3 April 2010
KEYWORDS: Optical proximity correction, Design for manufacturing, Design for manufacturability, Lithography, Manufacturing, Edge detection, Semiconductors, Photomasks, Critical dimension metrology, Mask making
Semiconductor foundries at 65nm, 45nm, and more advanced technologies have witnessed high-yield mass production to
be intimately correlated to the practice of adaptive DFM (Design for Manufacturability). With device performance
variance easily exceeding 50% for 65nm and below, adaptive actions by designers, such as modifying layouts to relieve
potential DFM risks, is found to be a very efficient approach to high yield manufacturing. Rigorous MEEF estimation
based methods have been proposed to achieve adaptive DFM by predicting mask writing variations at early stages
(cell/block levels) of designs.
In a recent study, we discovered that by adding MEEF check in simulation contour based OPC verification flow, and by
comparing MEEF changes of pre and post OPC hotspots, it is possible to separate OPC issues from design issues, in
particular, for hotspot patterns with tight spaces with little room for any biases. We found that hotspot patterns with tight
spaces usually create OPC conflict edges-correcting one edge will result in increasing MEEF at other edge, or vice
versa. While advancement in OPC technology continues to improve MEEF performance, nevertheless OPC-conflicting
edges almost always exist in designs at 65nm and below.
In this paper, we first demonstrate the existence of OPC conflict edge hotspots using MEEF analysis. In particular, the
increase of MEEF after OPC on those edges indicates that they have smaller process window than pre-OPC ones. In
certain cases, design modification is necessary to correct such OPC conflicting edges. Based on the finding, we propose
a practical methodology of detecting design related OPC edge conflicting hotspots in a pattern centric software-based
DFM (design for manufacturability) flow. The methodology is aiming to detect patterns containing such conflicting
edges, and pursuing layout actions on the design side to eliminate this issue. We will validate the flow using a real design
case. In addition, the OPC edge conflicting hotspots can be clipped and saved in a designated pattern library as hotspot
templates, and incoming designs can be quickly screened using exact and similar pattern search with those saved templates in the library.
