Figure 1: Xradia nanoXFi x-ray fluorescence imager installed on a JEOL JXA-8600 scanning electron microscope. The nanoXFi attaches to one of the ports of the SEM and images x-ray fluorescence radiation produced by the electron beam of the SEM. It has very high elemental sensitivity and sub-80nm spatial resolution.
Electron microscopy offers very high-resolution imaging of surface structures and limited elemental information through Z-contrast (backscattered electron imaging). For true elemental and compositional analysis, x-ray spectrometers are employed in conjunction with SEMs. They perform point analysis and can only deliver a coarse resolution map of elemental distribution by raster scanning the electron probe on the sample.
The Xradia nanoXFi x-ray fluorescence imager overcomes this limitation by combining the properties of an x-ray spectrometer with Xradia’s high-resolution x-ray imaging technology. The nanoXFi enables high-resolution (sub-80nm) elemental imaging of a selected element at a time of an extend area on the sample. By imaging several elements sequentially, phases of different alloys can be identified and the interface of these phases can be studied at high resolution.
This material is based upon work supported by National Science Foundation under Grant No. 0512910 and No. 0620578 "Development of an Imaging X-ray Spectrometer". Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
Figures 2a and 2b. The figure shows an interfacial area (polished cross section) between a copper post and a solder ball used in IC packaging applications. It is of great interest, which alloys form at the interface and how the phases separate spatially. In figure 2a, the imager was configured to image copper and in figure 2b, the imager was configured to image nickel. The nanoXFi image shows clearly the solid copper of the post, a pure Nickel phase, a Tin phase and an alloy composed of a mixture of Copper and Tin.