Acta Optica Sinica, Volume. 42, Issue 11, 1134005(2022)

Recent Progress in Nanofabrication of High Resolution X-Ray Zone Plate Lenses by Electron Beam Lithography

Yifang Chen*
Author Affiliations
  • School of Information Science and Technology, Fudan University, Shanghai 200433, China
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    This paper first reviews and comments on the performance of resolution and imaging efficiency of various types of X-ray lenses, and then discusses and predicts the roadmap of technical development of zone plate lenses in China, which was first established in 2013 by the author. Following the roadmap, the technical advance for the resolution from 70 nm up to 30 nm has been achieved by electron beam lithography with Au electroplating, based on the earlier success in 100 nm resolution zone plate lenses and convergent lenses for both soft and hard X-ray optics. When the resolution approaching 30 nm, the limitation to the aspect ratio (ratio of zone-height to zone-width) owing to the proximity effect in electron beam lithography becomes more and more severe. The commercial software packages, which are based on Monte Carlo model and development dynamics, are not able to manage the correction of proximity effect on the whole zone plate with the varying zone-widths from micrometers down to 30 nm. To overcome the difficulty, pattern correction of proximity effect is proposed in the electron beam lithography for 70 nm resolution zone plates and as high as 20∶1 for the aspect ratio has been realized. Furthermore, a local proximity effect correction is also developed in replicating 50 nm resolution zone plates and the aspect ratio of 15∶1 has been realized. In the attempt for 30 nm resolution zone plate lenses, pulsed Au electroplating is applied to eliminate the crystallization and epitaxial growth of Au, and 30 nm resolution zone plates for soft X ray are fabricated. For the characterizations of the fabricated zone plate lenses, high aspect ratio Siemens stars with various resolutions from 30 nm to 100 nm have been fabricated, which are used as standard samples for optical detection. 50 nm resolution imaging in both soft and hard X-ray has been demonstrated in Shanghai Synchrotron Radiation Facilities (SSRFs) for the first time in China by using completely in-house fabricated zone plate lenses.

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    Yifang Chen. Recent Progress in Nanofabrication of High Resolution X-Ray Zone Plate Lenses by Electron Beam Lithography[J]. Acta Optica Sinica, 2022, 42(11): 1134005

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    Paper Information

    Category: X-Ray Optics

    Received: Feb. 9, 2022

    Accepted: Apr. 18, 2022

    Published Online: Jun. 3, 2022

    The Author Email: Chen Yifang (yifangchen@fudan.edu.cn)

    DOI:10.3788/AOS202242.1134005

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