Imaging performance improvement of coherent extreme-ultraviolet scatterometry microscope with high-harmonic-generation extreme-ultraviolet source. (18th May 2017)

• Record Type: Journal Article
• Authors: Mamezaki, Daiki; Harada, Tetsuo; Nagata, Yutaka; Watanabe, Takeo
• Is Part Of: Japanese journal of applied physics. Volume 56:Number 6(2017)Supplement 1
• Publication Date: 2017-05-18
• Subjects: Physics -- Periodicals; 621.05
• DOI: 10.7567/JJAP.56.06GB01
• Languages: English
• ISSNs: 0021-4922

Abstract

Abstract: In extreme-ultraviolet (EUV) lithography, the development of a review apparatus for the EUV mask pattern at an exposure wavelength of 13.5 nm is required. The EUV mask is composed of an absorber pattern and a Mo/Si multilayer on a glass substrate. This mask pattern has a three-dimensional (3D) structure. The 3D structure would modulate the EUV reflection phase, which would cause focus and pattern shifts. Thus, the review of the EUV phase image is also important. We have developed a coherent EUV scatterometry microscope (CSM), which is a simple microscope without objective optics. The EUV phase and intensity images were reconstructed with diffraction images by ptychography. For a standalone mask review, the high-harmonic-generation (HHG) EUV source was employed. In this study, we updated the sample stage, pump-laser reduction system, and gas-pressure control system to reconstruct the image. As a result, an 88 nm line-and-space pattern and a cross-line pattern were reconstructed. In addition, a particle defect of 2 µm diameter was well reconstructed. This demonstrated the high capability of the standalone CSM, which can hence be used in factories, such as mask shops and semiconductor fabrication plants.