Studies on Defect Inspectability and Printability Using Programmed-Defect X-Ray Mask

The defect inspectability and printability of X-ray masks have been studied. To clarify the issues concerning the present inspection system, we made an X-ray mask programmed with various defects, such as clear and opaque defects, dimension error and positional shift, for typical patterns such as line-and-space (L&S), hole and 2-dimensional patterns. Both the mask pattern and printed pattern on the wafer were specially inspected using the electron-beam inspection system SEM-Spec701 for the case of L&S patterns. In order to estimate the sensitivity required of the next-generation inspection system, we investigated the critical dimension (CD) errors due to mask defects, by comparing the printed patterns of the programmed-defect mask and the dose image profile calculated with the lithographic simulator Toolset, developed at Wisconsin University. Based on these results, we discussed the critical mask defect sizes that result in 10 nm CD error, and found that defects larger than 40 nm would significantly affect 100 nm L&S patterns.