EUV patterned mask inspection with an advanced projection electron microscope (PEM) system

The framework and the current status of a newly developed PEM pattern inspection system are presented. A die-to-die defect detection sensitivity of the developing system is investigated. A programmed defect mask was used for demonstrating the performance of the system. Defect images were obtained as difference images by comparing PEM images with-defects to the PEM images without-defects. The image-processing system was also developed for die-to-die inspection. A targeted inspection throughput of 19-hour inspection per mask with 16nm pixel size for image capture was attained. Captured image of 28 nm intrusion defect in hp 64 nm L/S pattern was used for detection. The defect is clearly identified by the image processing. But several false defects are also detected. To improve the defect detection sensitivity to reach the targeted level of achieving a higher than 10 S/N value at 16 nm defect size, by applying a higher current density and a developed inspection algorithm adjustment is, currently an on-going program.