Non-destructive and quantitative imaging of a nano-structured microchip by ptychographic hard X-ray scanning microscopy

We used hard X-ray scanning microscopy with ptychographic coherent diffraction contrast to image a front-end processed passivated microchip fabricated in 80 nm technology. No sample preparation was needed to image buried interconnects and contact layers with a spatial resolution of slightly better than 40 nm. The phase shift in the sample is obtained quantitatively. With the additional knowledge of the elemental composition determined in parallel by X-ray fluorescence mapping, quantitative information about specific nanostructures is obtained. A significant enhancement in signal-to-noise ratio and spatial resolution is achieved compared to conventional hard X-ray scanning microscopy.

Coherent x-ray diffraction imaging with nanofocused illumination

Coherent x-ray diffraction imaging is an x-ray microscopy technique with the potential of reaching spatial resolutions well beyond the diffraction limits of x-ray microscopes based on optics. However, the available coherent dose at modern x-ray sources is limited, setting practical bounds on the spatial resolution of the technique. By focusing the available coherent flux onto the sample, the spatial resolution can be improved for radiation-hard specimens. A small gold particle (size <100 nm) was illuminated with a hard x-ray nanobeam (E=15.25 keV, beam dimensions approximately 100 x 100 nm2) and is reconstructed from its coherent diffraction pattern. A resolution of about 5 nm is achieved in 600 s exposure time.

Compact x-ray microtomography system for element mapping and absorption imaging

We have designed and built a compact x-ray microtomography system to perform element mapping and absorption imaging by exploiting scanning fluorescence tomography and full-field transmission microtomography, respectively. It is based on a low power microfocus tube and is potentially appropriate for x-ray diagnostics in space. Full-field transmission tomography yields the three-dimensional inner structure of an object. Fluorescence microtomography provides the element distribution on a virtual section through the sample. Both techniques can be combined for appropriate samples. Microradiography as well as fluorescence mapping are also possible. For fluorescence microtomography a small and intensive microbeam is required. It is generated using a polycapillary optic. Operating the microfocus tube with a molybdenum target at 12 W, a microbeam with a full width at half maximum lateral extension of 16 microm and a flux of about 10(8) photonss is generated. As an example of application, this beam is used to determine the element distribution inside dried plant samples. For full-field scanning tomography, the x-ray optic is removed and the sample is imaged in magnifying projection onto a two-dimensional position sensitive detector. Depending on the sample size, a spatial resolution down to about 10 microm is possible in this mode. The method is demonstrated by three-dimensional imaging of a rat humerus.