  High-resolution patterning of periodic structures over large areas has
several applications in science and technology. One such method, based on the
long-known Talbot effect observed with diffraction gratings, is achromatic
Talbot lithography (ATL). This method offers many advantages over other
techniques, such as high resolution, large depth of focus, high throughput,
etc. Although the technique has been studied in the past, its limits have not
yet been explored. Increasing the efficiency and the resolution of the method
is essential and might enable many applications in science and technology. In
this work, we combine this technique with spatially coherent and
quasi-monochromatic light at extreme ultraviolet (EUV) wavelengths and explore
new mask design schemes in order to enhance its throughput and resolution. We
report on simulations of various mask designs in order to explore their
efficiency. Advanced and optimized nanofabrication techniques have to be
utilized to achieve high quality and efficient masks for ATL. Exposures using
coherent EUV radiation from the Swiss light source (SLS) have been performed,
pushing the resolution limits of the technique for dense hole or dot patterning
down to 40 nm pitch. In addition, through extensive simulations, alternative
mask designs with rings instead of holes are explored for the efficient
patterning of hole/dot arrays. We show that these rings exhibit similar aerial
images to hole arrays, while enabling higher efficiency and thereby increased
throughput for ATL exposures. The mask designs with rings show that they are
less prone to problems associated with pattern collapse during the
nanofabrication process and therefore are promising for achieving higher
resolution.
