Confining Light to Deep Subwavelength Dimensions to Enable Optical Nanopatterning

• Published in: Science (American Association for the Advancement of Science) Vol. 324; no. 5929; pp. 917 - 921
• Main Authors: Andrew, Trisha L., Tsai, Hsin-Yu, Menon, Rajesh
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 15.05.2009; The American Association for the Advancement of Science
• Subjects: Biological and medical applications; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Industrial applications; Isomers; Lasers; Light; Light beams; Molecules; Nanotechnology; Nanotechnology - methods; Near fields; Optics; Optics and Photonics - methods; Photochemical Processes; Photons; Photoresists; Physics; Radiation; Standing waves; Wave diffraction; Wavelengths; Diffraction limit; Optical confinement; Subwavelength; Line widths; Far field; Nanostructures; Periodic structures
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1167704

In the past, the formation of microscale patterns in the far field by light has been diffractively limited in resolution to roughly half the wavelength of the radiation used. Here, we demonstrate lines with an average width of 36 nanometers (nm), about one-tenth the illuminating wavelength λ₁ = 325 nm, made by applying a film of thermally stable photochromic molecules above the photoresist. Simultaneous irradiation of a second wavelength, λ₂ = 633 nm, renders the film opaque to the writing beam except at nodal sites, which let through a spatially constrained segment of incident λ₁ light, allowing subdiffractional patterning. The same experiment also demonstrates a patterning of periodic lines whose widths are about one-tenth their period, which is far smaller than what has been thought to be lithographically possible.