Electromagnetic diffraction of a light wave by a single aperture of subwavelength width and subsequent propagation in a lossy medium are numerically investigated. This diffraction problem simulates exposure of a resist with an amplitude mask. It is found that there is the possibility of fabricating a λ/2 structure on a resist of λ/4 thickness, where λ is the wavelength of the exposing light in vacuum, by conventional contact or by proximity lithography. It is also found that an air gap between a mask and a resist of up to λ/2 does not have a significant effect on resolution. This approach permits easy and cost-effective fabrication of subwavelength structures and leads to wide availability of diffractive optical elements in the nonscalar domain.
© 2001 Optical Society of America
(050.1220) Diffraction and gratings : Apertures
(050.1380) Diffraction and gratings : Binary optics
(050.1970) Diffraction and gratings : Diffractive optics
(220.3740) Optical design and fabrication : Lithography
(220.4000) Optical design and fabrication : Microstructure fabrication
Hiroyuki Ichikawa and Hisao Kikuta, "Numerical feasibility study of the fabrication of subwavelength structure by mask lithography," J. Opt. Soc. Am. A 18, 1093-1100 (2001)