Quantitative Investigation of Laser Beam Modulation in Electrically Active Devices as Used in Laser Voltage Probing

Among the backside analysis techniques of integrated circuits, laser voltage probing provides signal levels of the nodes. In the past, signal interpretation has been empirically based. In this paper, for the first time, an in-depth investigation of signal origin and parametric measurements of active devices have been performed, and a concise physical model of laser beam absorption has been developed. In the laser measurements, switching metal-oxide-semiconductor field-effect transistors and their basic components - reverse-biased diodes and gates in inversion - have been studied parametrically. The results show the ranges and limits of linear signal-to-voltage correlation and match the model successfully.