Infrared active materials used in semiconductor devices have near-field characteristic spectra that allow them to be directly identified using neaSCOPE microscopes. The SEM image of the test structure of the transistor (gray) reveals different materials and highlights the interface between them thanks to the applied decorative etching. There are seven individual transistors. The topographic cross-sectional image of the sample shows a flat surface (result of the sample polishing process). The near-field amplitude image (in color) reveals a high signal for metal components, a medium-strength signal for the Si substrate, and a low signal for the insulating SiO.
Higher resolution single transistor measurements demonstrate the ability of neaSCOPE microscopes to analyze a single component. Depending on the laser frequency used for near-field imaging, the SiN or SiO parts of the transistor can be highlighted, as seen in the individual images. The dependence of contrasts on frequency can be explained by material-specific near-field resonances, which allows the identification of materials. The high sensitivity of near-field resonances to the dielectric properties of materials allows detailed analysis of single components.