Electrical characterization and inspection of contact plugs using laser-assisted SEM

In semiconductor manufacturing process, identification of device defects in early phase of the process flow is critical for accelerate process ramp-up times. On the other hand, the number of invisible electrical and material defects which cannot be detected by conventional dimensional metrology is increasing as semiconductor devices become more complex. To overcome this difficulty, we have developed an SEM equipped with two features: an electron beam modulator to generate pulsed electron beam and a laser irradiation feature. The laser enables control of the electrical state while the electron beam modulation enables charge dynamics measurement of device elements. In this report, we present (1) a technique to improve the detection sensitivity of contact defects by utilizing wavelength tunability and (2) evaluation results of contact resistance from voltage contrast using RC estimation systems.