電子線露光装置における環境適合ステージ開発

概要

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It has been generally mentioned that EPL(Electron beam Projection Lithography) system has theoretically enough resolution of wafer processing because an energized electron beam might be finely controlled by multi electric lenses, however the system is very sensitive to outside disturbances, gas molecule, particles and electromagnetic field. The former two issues could be solved by exposing the system into a vacuum environment. On the other hand, since the latter will potentially be a peculiar problem for this lithography system, some concepts for AC and DC magnetic compensation are discussed in this paper. Especially, an electromagnetic linear motor which is almost a defacto standard in commercial base lithography tools should be also adopted to Nikon's EPL wafer stage in order to establish a common platform, so a magnetic flux leak from motors, eddy current excited and magnetized materials must are protected against an electron beam axis. First, a magnetic affect from wafer stage components are estimated, then DC/AC magnetic shielding and canceling methods of motor are introduced, furthermore the concepts are verified by manufacturing a full-scale Nikon's EPL tool and experimented. The studies, magnetic analyses and test results of magnetically conformed stage for Nikon's EPL are reported in this paper.