Quantitative phase imaging of a small phase structure on an extreme-ultraviolet mask by coherent diffraction imaging. (21st April 2015)

• Record Type: Journal Article
• Authors: Harada, Tetsuo; Hashimoto, Hiraku; Tanaka, Yusuke; Amano, Tsuyoshi; Watanabe, Takeo; Kinoshita, Hiroo
• Is Part Of: Applied physics express. Volume 8:Number 5(2015:May)
• Publication Date: 2015-04-21
• Subjects: Physics -- Periodicals; Technology -- Periodicals; 621.05
• DOI: 10.7567/APEX.8.055202
• Languages: English
• ISSNs: 1882-0778

Abstract

Abstract: Extreme-ultraviolet (EUV) lithography poses a number of challenges. One of which is the production of a defect-free mask. To observe the phase defects on an EUV mask in a quantitative phase image, we have developed a micro-coherent EUV scatterometry microscope at the NewSUBARU synchrotron facility. This microscope focused coherent EUV on a 140-nm-diameter defect and recorded the diffraction. The intensity and phase images of the defect are reconstructed by the coherent diffraction imaging method of ptychography. Phase defects with a 30 nm spatial resolution were reconstructed. This quantitative phase imaging method should help improve EUV masks.