Required Performances of Reticle Inspection System for ArF Lithography: Through Analysis of Defect Printability Study

摘要

Semiconductor industry still inspect reticle with the i-line wavelength and ITRS indicates only minimum defect size corresponds to 20% of the pattern size on mask in the same light. Currently defect definition, however, varies from the fixed minimum defect size to non-printable-maximum defect size due to increased reticle cost. This paper provides an investigation of requirements of current inspection system 193nm lithography. The lines and contact holes patterns were also investigated by both simulation and experiment. The printability of defects was observed under the various circumstances such as pitch variation and transmission of halftone film. From the defect printability study we found that defect printability behave non-linearly as the exposure condition varies and the size defect should be treated importantly as the ArF lithography extends till 70nm era. It is also understood that there is a possibility to miss the important meaning of the size defects from the simple definition of reticle defect. From the analysis of various types of defects and exposure conditions we suggested detail level of inspection sensitivity that new reticle inspection system should be ready.