F. Pedaci

Microscopy of extreme ultraviolet lithography masks with 13.2 nm tabletop laser illumination

We report the demonstration of a reflection microscope that operates at 13.2 nm wavelength with a spatial resolution of 55+/-3 nm. The microscope uses illumination from a tabletop extreme ultraviolet laser to acquire aerial images of photolithography masks with a 20 s exposure time. The modulation transfer function of the optical system was characterized.

Highly coherent injection-seeded 13.2 nm tabletop soft x-ray laser

We report a dramatic improvement of the spatial coherence and beam divergence (0.66 mrad) of a 13.2 nm wavelength Ni-like Cd tabletop laser by injection seeding the soft x-ray laser amplifier with high-harmonics pulses generated in a Ne gas jet. This phase coherent laser is an attractive light source for at-wavelength interferometry of extreme ultraviolet lithography optics and other applications.

Inspection 13.2 nm table-top full-field microscope

We present results on a table-top microscope that uses an EUV stepper geometry to capture full-field images with a halfpitch spatial resolution of 55 nm. This microscope uses a 13.2 nm wavelength table-top laser for illumination and acquires images of reflective masks with exposures of 20 seconds. These experiments open the path to the realization of high resolution table-top imaging systems for actinic defect characterization.

Progress in the development of compact high-repetition-rate soft x-ray lasers: gain saturation at 10.9 nm and first demonstration of an all-diode-pumped soft x-ray laser

We report new advances in the development of high repetition rate table-top soft x-ray lasers. We have extended the gain-saturated operation of these lasers to 10.9 nm demonstrating a 1 Hz repetition rate laser operation in Ni-like tellurium with an average power of 1 microwatt. In a separate development we have demonstrated the first all-diodepumped soft x-ray laser. Lasing was achieved in the 18.9 nm line of Ni-like molybdenum in a plasma heated by a compact all-diode-pumped Yb:YAG laser. The solid state pump laser produces 8.5 ps pulses with up to 1 J energy at 10 Hz repetition rate. This diode-pumped laser has the potential to greatly increase the repetition rate and average power of soft x-ray lasers on a significantly smaller footprint. These compact soft X-ray lasers offer new scientific opportunities in small laboratory environments.

Phase-Coherent Injection-Seeded Soft X-rayLasers at Wavelengths Down to 13.2 nm

Lasers: We have created lasers with operating properties that we never would have dreamed of when the technology was invented 50 years ago.

Dense capillary discharge plasma waveguide containing Ag ions

Interferometry of plasmas generated by fast discharge excitation of Ag/sub 2/S microcapillary channels shows the formation of dense plasma waveguides capable of guiding intense laser beams. Discharge ablation of capillaries, 330 /spl mu/m or 440 /spl mu/m in diameter, with 3-5.5-kA current pulses formed concave plasma density profiles with axial electron density >1/spl times/10/sup 19/ cm/sup -3/. These dense plasma waveguides containing highly ionized metal atoms are of interest to the development of a longitudinally pumped soft X-ray lasers.

13.2 nm table-top inspection microscope for extreme ultraviolet lithography mask defect characterization

We report on a reflection microscope that operates at 13.2-nm wavelength with a spatial resolution of 55±3 nm. The microscope uses a table-top EUV laser to acquire images of photolithography masks in 20 seconds.

Generation of a 1 picosecond soft x-ray laser pulses from an injection-seeded plasma amplifier

Phase-coherent soft x-ray laser pulses of 1.13 ± 0.47 ps duration were generated by injection-seeding a solid-target Ne-like Ti plasma amplifier with high harmonic pulses. This is the shortest pulse duration reported to date from a table-top soft x-ray laser amplifier.

Table-top microscope for at-wavelength inspection of extreme ultraviolet lithography mask

Extreme ultraviolet lithography (EUVL) has been selected to print a new generation of semiconductor chips at the 22 nm half-pitch node and beyond. This technology has been demonstrated at laboratory and beta-tool scales but several technological issues, including the fabrication of defect-free masks, need to be addressed before it can be implemented for mass production of chips. In support of EUVL, there is a need to develop metrology tools capable of detecting printable defects on masks and mask-blanks. The most reliable way of detecting printable defects is to image the Mo/Si coated mask at the wavelength employed in the printing process, 13.5 nm. This is key to detect absorption contrast defects in the surface of the mask as well as phase defects generated from imperfections within the layers of the resonant-reflective multilayer coating.

Advances in full field microscopy with table-top soft x-ray lasers

We describe recent advances in the demonstration of table-top full field microscopes that use soft x-ray lasers for illumination. We have achieved wavelength resolution and single shot exposure operation with a very compact 46.9 nm microscope based on a desk-top size capillary discharge laser. This λ=46.9 nm microscope has been used to captured full field images of a variety of nanostructure systems and surfaces. In a separate development we have demonstrated a zone plate microscope that uses λ=13.2 nm laser illumination to image absorption defects in a extreme ultraviolet lithography (EUVL) mask in the same geometry used in a 4x demagnification EUVL stepper. Characterization of the microscopes transfer function shows it can resolve 55 nm half period patterns. With these capabilities, the λ=13.2 nm microscope is well suited for evaluation of pattern and defect printability of EUVL masks for the 22 nm node.