Scanning overlapped phase interference lithography system for manufacturing optical waveguide combiner

Yohei Nawaki,¹ Kentaro Nomoto,¹ Shunta Sugisaki,¹ Shinji Orihara,¹ Kazuyuki Tsuruoka<sup>1

1</sup>Ushio Inc. (Japan)

我々は静定精度1nmの大面積ステージとコリメートされた266nmのレーザー光を用いた、干渉縞重ね合わせスキャン干渉露光装置を開発した。重ね合わせスキャン方式とは、干渉縞周期の整数倍だけ露光エリアをシフトさせ、重ね合わせながらφ200mmウェハ全体をスキャン露光する新しい技術である。干渉縞を1nm以下の位置精度で重ね合わせながらスキャンすることによって、φ200ｍｍウェハ全面において、ピッチ均一性+-0.002%の露光を達成した。また、ピッチ180 nmの露光も安定していることを確認した。

We have developed Scanning Overlapped Phase Interference Lithography (SOPHIL) system consisting of precisely controlled work-stage with static accuracy of 1 nm, and collimated laser beams with wavelength of 266 nm. SOPHIL method is a new technology. As the first step, a spot fringe pattern generated by two-beam interference is scanned direction along the grid on the wafer. As the second step, the spot is moved just the integer multiple length of its fringe period, then the spot is exposed again over the 1st fringe pattern. The reason moving amount of spot pattern must be the integer multiple length is to match fringe phases between 1st and 2nd scan perfectly to obtain high contrast exposure. We achieved the pitch uniformity of +-0.002% across the entire 200 mm diameter wafer by exposing with a position accuracy of less than 15 nm. And also 180 nm pitch pattern was confirmed showing good stability as a mass production equipment for waveguide combiner. 

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