Structured light assisted coherent fourier scatterometry for physical parameter retrieval of nanostructures

Abstract

In the semiconductor industry, the minimumelement size has stepped into nanometer level. To keep the functionality of fabricated nanostructures, there is a huge demand of a technique that can provide non-destructive inspection and allow for in-line or in-situ monitoring during the manufacturing process. Optical scatterometry, which uses the far-field optical scattering information to retrieve the geometrical features of a structure, is a suitable method. As a non-imaging technique, optical scatterometry does not produce images of the illuminated object. Optical scatterometry relies on retrieving nanostructure profile parameters by continuously comparing the given set of predicted signatures expected from a scattering experiment with the actual measured ones. Because we parametrize the structure with a limited set of parameters (i.e. we use prior knowledge of the structure), we can reconstruct the structure with a resolution beyond the diffraction limit. This technique is particularly valuable for characterizing micro- and nano-scale structures that are commonly found in semiconductor devices and integrated circuits ....