(Color online) Schematic of the experimental setup for extreme ultraviolet Talbot coherent lithography. The collimated coherent extreme ultraviolet beam illuminates a periodic transparent mask that renders a Talbot image at the Talbot distance, where a photoresist-coated substrate is placed.
(Color online) Free standing Talbot masks fabricated in a silicon nitride membrane. The mask is composed of 5 × 5 μm2 tiles replicated 10 000 times in a square matrix. About 20% of the tiles have broken bridges (shown in the image). (a) Mask with tiles composed of 500 nm slits with a periodicity of 600 nm. (b) SEM image of a self-standing mask with tiles composed of 300 nm holes in 1.2 μm period. (c) Cross section diagram of the free-standing mask.
(Color online) Talbot masks supported on a silicon membrane: (a)SEM image of a mask with elbow shaped patterns with 550 nm wide lines and period 1.2 μm. (b) SEM image of a mask with 500 nm isolated lines and a period of 1 μm. (c) Cross section scheme of the mask supported on a Si membrane.
(a) SEM image of a self-standing mask with approximately 20% defective tiles. The mask is also depicted in Fig. 2(a) . (b) Exposed pattern in a 60 nm thick HSQ layer using the mask shown in (a). The HSQ pattern (bright lines in the image) on top of the gold substrate is free of defects. (c)SEM image of the pattern transferred to 100 nm thick gold using anisotropic ion beam etching.
(Color online) Examples of periodic structures fabricated in metal-coated substrates. (a) SEM and AFM (inset) images of Au pillars 80 nm in height and 300 nm FWHM diameter obtained with the mask shown in Fig. 2(b) . (b) SEM image of Au elbows 100 nm in height and 1.2 μm in period duplicated from mask shown in Fig. 3(a) . (c) SEM image of periodic and isolated lines in 120 nm thick Ag duplicated from mask shown in Fig. 3(b) .
(Color online) SEM images of free-standing masks fabricated in silicon nitride membranes. (a) Mask with 100 nm dense lines. (b) Mask with 75 nm dense lines. Both masks have a periodicity of the tiling of 2.85 μm and are composed of 180 × 180 tiles covering a surface of 512 × 512 μm2. The tiles have extra 40 nm supporting bridges along the direction of the slits to strengthen the self-standing structure.
(Color online) Reduction of the feature size by two overlaid exposures. (a) AFM images of 50 nm/150 nm gratings in photoresist obtained with the mask shown in Fig. 6(a) . The inset is a cross section of the AFM profile. (b) SEM image of 40 nm/110 nm line and spaces in photoresist. The inset is a cross section of the AFM profile. Figure 7(b) is a print obtained with the mask shown in Fig. 6(b) . (c) Higher magnification AFM scan of one tile of the print shown in Fig. 7(a) .
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