Finite element modeling of capacitive coupling voltage contrast

Capacitive coupling voltage contrast (CCVC) is proven to be able to detect broken track in high density organic substrate with solder mask on top of the tracks. In this work, we develop a finite element model to solve the electromagnetic equations and determine the surface voltage of the solder mask under the interaction of the electron beam and the electrostatic induction due to the biasing of the underlying track. As the brightness of an image under SEM depends on the surface voltage of the object under observation, our model is able to explain the experimental observations of CCVC accurately. This model also examines the limitation of the CCVC.