We report on x-ray microscopy of advanced microelectronic devices imaged in Zernike-type phase contrast mode at 4 keV photon energy. Fresnel zone plates were used as high resolution x-ray objectives providing 60 nm spatial resolution. Integrated circuit copper interconnect structures were imaged in positive as well as negative phase contrast. In both cases the phase contrast in the x-ray images is about five times higher than the pure absorption contrast.

In this article we describe a new slit grating spectrograph which is based on an e-beam written 10 000 linepairs/mm freestanding transmission diffraction grating. In combination with a thinned, back-illuminated charge coupled device (CCD), the spectrograph allows for real-time spectroscopy of laser-produced plasma x-ray sources within the wavelength region λ=1–20 nm. Calibration of grating and CCD allow for the possibility to measure absolute photon fluxes, currently within the wavelength region λ=1–6 nm. The compact spectrograph is easy to align and flexible in its use. Absolutely calibrated spectra were obtained from a liquid-jet laser-plasma source in the water window, with a spectral resolution λ/Δλ⩾330 at λ=3.37 nm. A simple change in experimental geometry allowed single-shot spectra to be recorded with λ/Δλ⩾60 at the same wavelength. In addition, spectra from this laser-plasma source were measured within the range λ=9–20 nm.

Design and application of a zone plate monochromator for laboratory soft x-ray sources Rev. Sci. Instrum. 72, 53 (2001); A slit grating spectrograph for quantitative soft x-ray spectroscopy Rev.

Quantitative time-resolved x-ray microscopy mass transport studies of the early stages of electromigration in an inlaid Cu line/via structure were performed with about 40 nm lateral resolution. The image sequences show that void formation is a highly dynamic process, with voids being observed to nucleate and grow within the Cu via and migrate towards the via sidewall. Correlation of the real time x-ray microscopy images with postmortem high voltage electron micrographs of the sample indicates that the void nucleation occurs at the site of grain boundaries in Cu, and that the voids migrate along these grain boundaries during electromigration.

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