Technique for site-specific plan-view transmission electron microscopy of nanostructural electronic devices

This brief report demonstrates the feasibility of preparing site-specific plan-view samples of simple electronic devices and nanostructures for the transmission electron microscope (TEM). By combining the techniques of tripod angle lapping and single-sided ion milling in a different way, we are able to target specific devices for analysis in the TEM. This is essentially performed by back-angle lapping a patterned wafer that contains multiple features so that an edge is at or near a level of electron transparency. At this point, the sample is glued to a copper ring using conducting epoxy, and a piece of protective transparent material (preferably a piece of glass) is waxed to the device face in order to protect the device from sputtering and material redeposition on the opposite side. The device is then milled in a liquid-nitrogen-cooled ion mill in order to avoid specimen heating (which would melt the wax). By aligning the device of interest perpendicular to the lapping angle, the device may be examined optically as it is milled back to the feature of interest. This technique was used to examine the active region of a gold nanoparticle-based device to observe the alignment of these particles between two contact pads. This result is extremely promising because it allows the observation of materials on a lateral scale that are extremely sensitive to damage by sputtering. This sample preparation technique would be useful for researching various processing steps in the design of electronic devices, as well as patterned samples in general.