Development of the point diffraction interferometer for extreme ultraviolet lithography: Design, fabrication, and evaluation

被引：72

作者：

Otaki, K ^{[1
]}

Ota, K ^{[1
]}

Nishiyama, I ^{[1
]}

Yamamoto, T ^{[1
]}

Fukuda, Y ^{[1
]}

Okazaki, S ^{[1
]}

机构：

[1] NTT Atsugi R&D Ctr, ASET, Kanagawa 2430198, Japan

来源：

JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B | 2002年 / 20卷 / 06期

关键词：

D O I：

10.1116/1.1526605

中图分类号：

TM [电工技术]; TN [电子技术、通信技术];

学科分类号：

0808 ; 0809 ;

摘要：

A point diffraction interferometer (PDI) for extreme ultraviolet lithography (EUVL) aspheric mirror measurement has been developed. In order to realize an accuracy of 0.1 nm rms, various optical error factors have been numerically analyzed and the maximum tolerable error has been determined. From the error estimation results, the optimal pinhole diameter has been determined as 0.5 mum. In a PDI, air turbulence reduces the precision and accuracy because of the long optical path. In order to avoid this problem, the apparatus is filled with helium gas, which has a smaller refractive index than that of air. By using this apparatus, precision of 0.03-0.04 nm rms and a system error of 0.10 (0.16) nm rms have been obtained for a spheric mirror with numerical aperture (NA) 0.08 (0.15). In aspheric mirror measurement, an accuracy of 0.74 (1.18) nm rms for NA 0.08 (0.15) has been obtained. The accuracy becomes 0.34 (0.97) nm rms for NA 0.08 (0.15) with 36-term Zernike polynomial fitting. (C) 2002 American Vacuum Society.

引用

页码：2449 / 2458

页数：10

共 28 条

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