Inspectability Study of Advanced Photomaska With OPC Structures

摘要

In the effort to extend the life of a technology node, reticle enhancement techniques are utilized extensively. The inspectability of advanced photomasks becomes increasingly difficult as OPC (Optical Proximity Correction) structures are incorporated in the mask design. OPC structures, such as serifs and sub-resolution assist features, are sub-specification (below the defined specification) geometries for the inspection tool. This makes it difficult to maintain high sensitivity on contamination inspection, while not detecting these OPC structures as false defects. Mask inspection can be broken down into two categories: pattern integrity and contamination, the latter of which is the topic of this paper.