Evanescent interferometric lithography.
ABSTRACT Simulation results are presented to illustrate the main features of what we believe is a new photolithographic technique, evanescent interferometric lithography (EIL). The technique exploits interference between resonantly enhanced, evanescently decaying diffracted orders to create a frequency-doubled intensity pattern in the near field of a metallic diffraction grating. It is shown that the intensity in a grating's near field can be enhanced significantly compared with conventional interferometric lithography. Contrast in the interference pattern is also increased, owing to a reduction in the zeroth-order transmission near resonance. The pattern's depth of field reduces as the wavelength is increased beyond cutoff of the first-order diffracted components, and results are presented showing the trade-offs that can be made between depth of field and intensity enhancement. Examples are given for a 270-nm-period grating embedded in material with refractive index n = 1.6 and illuminated with wavelengths near 450 nm. Under these conditions it is predicted that high-intensity, high-contrast patterns with 135-nm period can be formed in photoresists more than 50 nm thick.
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ABSTRACT: A recently proposed novel plasmonic lithographic concept and methodology based on the excitation of gap modes in a metal particle-surface system is discussed in this chapter. TheLithography, 02/2010; , ISBN: 978-953-307-064-3
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ABSTRACT: In this paper, we report progress in developing a scanning evanescent wave lithography (EWL) imaging head with a twostage gap control system including a DC noise canceling carrying air bearing that floats at a constant air gap with regulated air pressure, and an AC noise canceling piezoelectric transducer with real-time closed-loop feedback from gap detection. Various design aspects of the system including gap detection, prism design and alignment, software integration, feedback actuation and scanning scheme have been carefully considered to ensure sub-100 nm gapping. To validate the design concepts, a prototyped scanning EWL imaging head is integrated into a two-beam interferometer platform for gapping tests and imaging evaluation. Experimental results show successful gap gauging at sub-100 nm with gap noise root-mean-square around 1.38 nm in static gapping and 4.64 nm in linear scanning gapping. We also demonstrate scanning imaging results with NA comparable to previously reported static imaging using both fused silica prism and sapphire prism. Our gapping and imaging results confirmed the promise of scanning EWL to extend optical lithography to sub-22 nm generations.Proceedings of SPIE - The International Society for Optical Engineering 03/2012; 12(1):27-. DOI:10.1117/12.917955 · 0.20 Impact Factor
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ABSTRACT: The near-field imaging properties of planar silver layers are reviewed here, with a view to identifying their potential and pitfalls for sub-100 nm photolithography. Initial studies have shown that half-pitch features of 60–70 nm can be achieved using simple contact exposure with low-cost mercury lamp sources, which is less than 1/5th of the exposure wavelength. Sub-100 nm isolated features and line pairs with sub-100 nm spacing have also been resolved, and conventional resolution limits are exceeded in these cases too. Multi-layer silver lenses have also been studied, as it has been predicted that these will improve image resolution for a fixed mask-resist separation. Initial experimental results are inconclusive, as roughness on the additional interfaces tends to mitigate the benefits of going to the laminated structure. Simulations have been used to support the findings of the silver-lens experiments, and it is predicted that sub-50 nm half-pitch resolution should be possible.Microelectronic Engineering 04/2006; DOI:10.1016/j.mee.2006.01.056 · 1.34 Impact Factor