To provide a device and a method for enhancing voltage contrast of a wafer.

In a system for electrically testing a semiconductor wafer, the system includes a step of scanning a first zone by a defocused charged particle beam so as to have an effect on electrostatic charge of the first zone of a sample, and a step of scanning at least a part of the first zone by a focused charge particle beam and detecting dispersed electrons from at least its part of the first zone. At least the part of the first zone is scanned while the first zone has an influence of the electrostatic charge introduced by the defocused charged particle beam.