Trends in e-beam metrology and inspection

For many years, e-beam SEM metrology has been quite conservative. However, a few years ago, we began to observe a sort of restlessness in the field, a trend that was consistently confirmed year after year since then. Such a change was mainly driven by the daunting specification requirements for the advanced metrology nodes and High Numerical Aperture Extreme Ultraviolet Lithography (High NA EUVL), as well as by the device evolution in terms of architecture. We observed a systematic attempt to expand the application space in which the e-beam SEM had operated, tackling issues ranging from metrology of 3D structures to edge placement error, voltage contrast, e-beam inspection, and more. Such an expansion of the application space has forced heavily automated SEM to evolve into something different: a more flexible and powerful e-beam tool focusing not only on CD metrology, but on a range of novel use cases. To implement these new applications, it soon became evident that it was necessary to expand the range and type of tool specifications and features. We observed changes in landing energy, beam current, resolution, as well as algorithms. The detection process changed too, and higher current and better detection efficiency opened the door to a variety of back-scattered electron applications. Artificial intelligence is now critical not only in terms of speed of analysis, but most importantly for the quality of its results. Multibeam tools are fast approaching and have the potential to become a central technology element in the high-NA EUVL environment, where resolution and throughput for inspection must go hand-in-hand. In this paper, we provide an overview of the recent trends in e-beam metrology and inspection.