Advanced Dynamic Laser-Stimulation Methods Using Lock-In and Mixed-Frequency Techniques

A wide range of electrical faults are revealed through thermal laser stimulation (TLS). In principle, an electrical parameter, typically current or voltage, is monitored for changes caused by the heating effects of the laser. Most test setups are designed to limit the activity of the device in order to minimize the signal-to-noise ratio, but in some cases, the fault’s electrical footprint can only be detected when the device is stimulated in a dynamic way. This article describes the setup and implementation of various dynamic TLS methods and presents example applications demonstrating the advantages and limitations of each approach.