Monte Carlo-based SEM image simulation can reproduce SEM micrographs by calculating scattering events of primary electrons inside the target materials. By using the simulated SEM images, it is possible to optimize imaging conditions prior to the specimen observation, which could save time for finding suitable observation condition. However, a recent trend of miniaturized and 3-dimentional structures of semiconductor devices, and introduction of various novel materials have created a challenge for such SEM image simulation techniques; that is, more precise and accurate modeling is required. In this paper, we present a quantitatively accurate BSE simulation and a precise parameters setting in voltage contrast simulation, for both to reproduce experimental SEM images accurately. We apply these simulation techniques to optimize the accelerating voltage of SEM for sub-surface imaging, and to analyze a charge distribution on the insulating specimen under the electron irradiation. These applications promise the advancement in developing a new device by preparing inspecting condition in a timely manner.
The early detection of Cu sub-surface voids in nano-interconnects has become a main challenge with the reduction of the
critical dimensions of the interconnects. A new methodology for full wafer Cu void inspection with high sensitivity and
high speed has been developed using a Multi-Purpose SEM (MP-SEM) using high accelerating voltage, high resolution
and multi BSE detectors. This inspection methodology has been used to evaluate the Cu metallization quality in nanointerconnects.
The effectiveness of this inspection methodology was proven through the evidence of relations between
Cu void density, trench widths, pattern density, and surrounding dummy structures.