近接X線露光におけるセクタフレネルゾーンプレートによるアライメント計測

概要

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Fresnel rone plate patterns have been widely applied to mask to wafer alignment because the fresnel beam spots are unafiiected by poor edge definition or by rough sufaces arising fiom variation in processing. This paper deecribes a video-based alignment using a sector fresnel zone plate (SFZP) which is wlique among the rone plates in having an oblique line focus. SFZPs printed on both X-ray mask and wafers are illuminated with conimated He-Ne laser beam. The bright image formed on an oblique line focus shows high contrast better than 11-15dB in signal to background ratio. With SFZPs, position eensing repeatability better than 9 nm (3σ) has been obtained in four processed wafer types.
2001-02-05