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Proceedings Paper

Superresolution optical microscope by the phase-shifting laser spots
Author(s): Isao Shimizu; Y. Takahara; Y. Koshikiya; S. Aotani; Haruyoshi Toyoda
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Paper Abstract

A new method for optical microscopy with super-resolution exceeding the Rayleigh limit was developed to observe the shape of particles contaminating the LSI patterned wafer in the far- field. The principle of the new method is as follows. The optical spot being smaller than the measured particles has to be scanned on the particle to measure the shape of particles on the wafer. The phase-shifting mask making small optical spot consists of the checkered mask which has been coated with a transparent layer patterned to ensure that the optical phases of the nearest apertures are opposite. The destructive interference between the two opposite phases of light waves from adjacent apertures cancels some diffraction effects and increases the spatial resolution, so that the size and resolution of the coherent laser spots can exceed the size limit of the Airy disk and resolution of Rayleigh limit. The new method for optical microscope with super resolution was examined theoretically and experimentally. The coherent beam generated from 15 mW He-Ne laser projected to the phase-shifting checkered mask forms small laser spots of which size are under 0.1 micrometers in diameter. It is clarified that in the far-field, the scattered light from two spots with opposite phases on the wafer can be observed in exceeding with Rayleigh limit.

Paper Details

Date Published: 10 December 1992
PDF: 10 pages
Proc. SPIE 1752, Current Developments in Optical Design and Optical Engineering II, (10 December 1992); doi: 10.1117/12.130733
Show Author Affiliations
Isao Shimizu, Ibaraki College of Technology (Japan)
Y. Takahara, Ibaraki College of Technology (Japan)
Y. Koshikiya, Japan Synthetic Rubber Co. Ltd. (Japan)
S. Aotani, Japan Synthetic Rubber Co. Ltd. (Japan)
Haruyoshi Toyoda, Hamamatsu Photonics K.K. (Japan)

Published in SPIE Proceedings Vol. 1752:
Current Developments in Optical Design and Optical Engineering II
Robert E. Fischer; Warren J. Smith, Editor(s)

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