When performing intellectual property analysis to determine whether or not patents have been infringed upon, it is often important to closely study the materials and processes used to construct a specific device; the minutiae of how a transistor is formed can be crucial to the claims of a given patent. Traditionally mechanical cross-section and SEM inspection have been used to gather this data; however, these techniques have limited precision and resolution, and are not ideal for differentiating very small constructions (for example, the layers of oxide and nitride used as tunneling barriers in memory cells). Furthermore, a traditional mechanical section is not a good fit for performing elemental analysis of the layers of a device, as the interaction volume of the electron beam is so large that isolating individual layers to determine their composition is impossible. To better serve this market segment, IAL has added focused ion beam (FIB) and scanning transmission electron microscopy (STEM) capabilities. Rather than performing a mechanical cross-section (which involves polishing an entire integrated circuit until enough material has been removed that the device of interest is visible), the FIB can be used to perform targeted micro-sections, lifting out areas of the device only a few microns wide for analysis. These micro-sections are then imaged using STEM, which can provide the sub-nanometer resolution necessary to resolve even the most cutting edge devices (the image above is of a 22-nanometer tri-gate process, Intel’s solution to the challenges posed by process shrinks beyond the 32-nanometer node). STEM must be performed on exceptionally thin samples (for best resolution, samples must be 100 nanometers thick or less); a byproduct of working with such thin samples is increased spatial resolution for elemental analysis tools like energy dispersive spectroscopy, since the size of the sample provides a natural limit on the interaction volume of the electron beam. As a result, not only can very small, thin layers be imaged with higher clarity, their composition can also be analyzed.
Intellectual property analysis does not always mean diving in to a sample in order to determine whether patents have been infringed upon. There are vast segments of industry that rely on obsolete or legacy components, due to the extensive characterization history available. Many of these devices are no longer supported by their original manufacturer; that said, the demand for these components is still present. There are a limited number of solutions for engineers who need to source these obsolete components. They may turn to third party supplier and the “grey market”, where they have no guarantee of a component’s remaining lifespan or authenticity; others may choose to reverse engineer the device and have it manufactured by another foundry. In order to reverse engineer such a component, an engineer must be able to capture the layout and schematic of a device; SEM mosaics, one of the new electron microscopy services offered at IAL, provides a significant portion of the data needed to do so. By creating high resolution, large area composite images of functional blocks (or, in some cases, entire die), it is possible to grab the floor plan of a device with minimal engineering interaction. In some cases, these composite images can even be used as the input to specialized image recognition software that converts the images directly into GDSII layout files, cutting down immensely on the amount of engineering time necessary to recover an obsolete IC.
Electron microscopy services can provide key data for many types of intellectual property analysis; patent research, reverse engineering, and many others benefit from the rapid, high resolution imaging and compositional analysis techniques made possible by the electron microscope. As technology continues to push the boundaries of size, creating smaller and smaller features, electron microscopy will only continue to grow in value.