The study of relationship between defect sensitivity and inspectability on EUV masks with 19x nm mask inspection

Based on the record for reasonable throughput, 19x nm wavelength inspection is one of the strongest candidates available today for the initial EUV (Extreme Ultraviolet) mask inspection approach until high-throughput E-Beam or actinic inspection is ready. However, there are several key challenges with 19x nm optical inspection of EUV masks. In the previous study, it was demonstrated that a 19x nm inspection system was capable of detecting programmed 15nm edge defects and 7nm CD errors on the programmed defect mask (PDM) containing EUV device designs, and inspected at maximum sensitivity. However, in that study, the inspectability on the product mask was not considered. In this study, EUV product mask inspection with a 19x nm inspection system is demonstrated, with special attention paid to defect sensitivity and inspectability on the product mask. In our results, we discuss whether inspection conditions, such as focus, can be employed to create a trade-off between defect sensitivity and inspectability. In addition, we discuss how defect measurement definitions affect the programmed defect size and the printability on EUV AIMS.