The authors present a self-imaging lithographic technique, capable of patterning large area periodic structures of arbitrary content with nanoscale resolution. They start from the original concept of Talbot imaging of binary gratings-and introduce the generalized Talbot imaging ͑GTI͒ where periodic structures of arbitrary shape and content form high-definition self-images. This effect can be used to create the complex, periodic patterns needed in the many lithographic fabrication steps of modern semiconductor devices. Since the process is diffraction limited, the achievable resolution depends only on the wavelength, mask patterning, and degree of coherence of the source. Their approach removes all the complex extreme ultraviolet ͑EUV͒ reflective masks and optics, replacing them with nanopatterned transmission masks and makes the whole process simple and cost effective. They have successfully verified the GTI concept using first a He-Ne laser, and then demonstrated its potential as a nanolithography method using a compact table-top soft x-ray ͑EUV͒ 46.9 nm laser source. These sources provide the high degree of coherence needed by diffraction-based imaging and are extendable to shorter wavelengths. They have recorded EUV GTI images up to the sixth Talbot plane, with consistent high quality good results, clearly demonstrating the ability of the GTI method to record high-resolution patterns at large distances.

We present a defect-free lithography method for printing periodic features with nanoscale resolution using coherent extreme ultraviolet light. This technique is based on the self-imaging effect known as the Talbot effect, which is produced when coherent light is diffracted by a periodic mask. We present a numerical simulation and an experimental verification of the method with a compact extreme ultraviolet laser. Furthermore, we explore the extent of defect tolerance by testing masks with different defect layouts. The experimental results are in good agreement with theoretical calculations.

We report the measurement of the linewidth and temporal coherence of a λ = 46.9 nm neon-like argon capillary discharge soft-x-ray laser and its variation with plasma column length. A wave-front-division interferometer was used to resolve the 3p 1 S 0 -3s 1 P 1 laser line, resulting in measured relative linewidths of λ/λ = (3-4) × 10 −5 . The measurements do not observe saturation rebroadening when this clearly dominantly Doppler-broadened inhomogeneous line is amplified beyond the intensity corresponding to gain saturation. Model simulations indicate this is the result of a comparatively small collisional broadening that sufficiently homogenizes the line profile to practically eliminate inhomogeneous saturation rebroadening. Collisional redistribution is computed to play only a very minor role in homogenizing the line profile.

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We report the uninterrupted operation of an 18.9 nm wavelength tabletop soft x-ray laser at 100 Hz repetition rate for extended periods of time. An average power of about 0.1 mW was obtained by irradiating a Mo target with pulses from a compact diode-pumped chirped pulse amplification Yb:YAG laser. Series of up to 1.8 x 10(5) consecutive laser pulses of ~1 µJ energy were generated by displacing the surface of a high shot-capacity rotating molybdenum target by ~2 µm between laser shots. As a proof-of-principle demonstration of the use of this compact ultrashort wavelength laser in applications requiring a high average power coherent beam, we lithographically printed an array of nanometer-scale features using coherent Talbot self-imaging.