Electrooptical investigations such as laser voltage probing (LVP) and dynamic laser stimulation (DLS) are very popular electrical fault isolation techniques (EFI) that use lasers on semiconductor circuits to study the functionality of transistors while the device is in operation. While many studies have been undertaken to understand interaction between laser and planar devices, three-dimensional devices such as FinFETs have interesting physiologies that have not been fully explored. In this work, we study the interaction of polarized light with the n-type metal oxide semiconductor (NMOS) FinFETs, experimentally and through Multiphysics simulations. We report highly directional electrooptical interactions in the FinFET. LVP signals are stronger when the laser used is polarized parallel to the fin and laser stimulation stronger when the laser used is polarized parallel to the gate. These findings affect future laser stimulation and probing investigations for EFI.

Short wavelength probing (SWP) uses wavelengths of light shorter than 1100 nm or energies higher than silicon bandgap for laser probing applications. While SWP allows a significant improvement to spatial resolution, there are aberrations to the collected laser probing waveforms which result in difficulties in signal interpretations. In this work, we assess the signals collected through SWP (785 nm) and introduce a photodiode model to explain the observations. We also present a successful case study using 785 nm for failure analysis in sub-20 nm FinFET technology.