Yoshihiko Naito

Development of novel projection electron microscopy (PEM) system for EUV mask inspection

In order to realize pattern defect inspection for 1Xnm EUV mask, we are developing a novel projection electron microscopy (PEM) system; which enables us to make the inspection in high resolution and high speed as compared with conventional DUV and EB inspection systems. In this paper, we have cleared how progress is needed to the decided specification target, e.g., sensitivity of 16nm size in pattern defect and inspection speed of 19 hours/100mm square, as compared to the current PEM optics performance. Then, to achieve the progress, we made a new design concept, i.e., a novel PEM optics employing high electron energy as compared to the current PEM optics, and verifying the concept by using numerical estimations. The results show that the novel PEM optics design concept is capable to meet the progress and the target for 1Xnm EUV mask.

Development of optical system on novel Projection Electron Microscopy (PEM) for EUV masks and its basic performance evaluation

In order to realize pattern defect inspection for 1Xnm EUV mask, we are developing a novel projection electron microscopy (PEM) system; which enables us to make the inspection in high resolution and high throughput as compared with conventional DUV and EB inspection systems. To achieve the specification target, e.g., sensitivity of 16nm size in pattern defect and inspection speed of 19 hours/100mm square, we have examined to clear the required progress as compared to the current optical system for PEM; In order to meet the required progress, we made a new design concept and developed a new optical system, which comprises an exposure and an imaging electron optics. In this paper, we describe the evaluation on the basic performance of the developed optical system as concerning to the required progress: 1) transmittances over 10 times on the developed exposure optics and over 2 times on the developed imaging optics; 2) electron imaging being higher energy over 5 times and MTF inclination in hp44～64nm L/S pattern. The results show the developed optical system on the novel PEM is capable to meet the progress for 1Xnm EUV mask inspection.