Abstract
In this work, a masking technique was used to improve the thickness uniformity of a Mo/Si multilayer deposited on a curved spherical mirror by direct current (DC) magnetron sputtering with planetary rotation stages. The clear aperture of the mirror was 125 mm with a radius of curvature equal to 143.82 mm. Two different shadow masks were prepared; one was flat and the other was oblique. When using the flat mask, the non-uniformity considerably increased owing to the relatively large gap between the mask and substrate. The deviation between the designed and measured layer thickness and non-uniformity gradually reduced with a smaller gap. The second mask was designed with an oblique profile. Using the oblique mask, the deviation from multilayer thickness uniformity was substantially reduced to a magnitude below 0.8% on the curved spherical substrate over the clear aperture of 125 mm. Multilayers still achieved a smooth growth when deposited with obliquely incident particles. The facile masking technique proposed in this study can be used for depositing uniform coatings on curved spherical substrates with large numerical apertures for high-resolution microscopes, telescopes, and other related optical systems.
Highlights
Extreme ultraviolet (EUV) light sources, such as free electron lasers (FELs) [1,2], high harmonic generation devices [3], and plasma-based sources [4,5], produce ultra-short radiation with extremely high intensity
The multilayer thickness ondepicted a rotating determined by measuring the multilayer thicknesses on the distribution silicon pieces in substrate
By projecting the normalized coating thickness to different planes used for different mask designs, by projecting the normalized coating thickness to different planes used for different mask designs, the different thickness distributions will be obtained
Summary
Extreme ultraviolet (EUV) light sources, such as free electron lasers (FELs) [1,2], high harmonic generation devices [3], and plasma-based sources [4,5], produce ultra-short radiation with extremely high intensity. Using the simplest high-NA optical system consisting of two mirrors [7], a tabletop EUV focusing optical system with an operational wavelength of 13.5 nm was developed at the Institute of Precision Optical Engineering (IPOE) for investigating the damage of optical elements caused by EUV radiation [8]. This optical system contains a modified Schwarzschild objective [5] with an NA of 0.44 and two mirrors with the same radius of curvature (RoC) equal to 143.82 mm.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
