Nano-scale imaging with tabletop soft X-ray lasers: Sub-38 nm resolution

We report the demonstration of soft x-ray microscopes with resolution down to sub-38 nm using tabletop soft x-ray laser illumination. One of the compact microscopes combines the 46.9 nm wavelength output from a capillary discharge Ne-like Ar laser with a reflective condenser and a free standing zone plate objective. High quality images were acquired with this microscope in transmission mode and reflection mode. The latter includes images of an integrated circuit pattern containing polysilicon features on silicon. The spatial resolution for this microscope is between 120-150 nm. Increased resolution was demonstrated in another microscope using 13.2/13.9 nm wavelength illumination from Ni-like Cd/Ag transient soft x-ray lasers in combination with diffractive zone plate optics for both the condenser and objective. Using an objective zone plate with a 50 nm outer zone width, this optical system achieved a record sub-38 nm spatial resolution. These results demonstrate the feasibility of using compact high repetition rate soft-x-ray laser sources in nanometer-scale microscopy.