A dual-phase interferometric method and device for charge modulation mapping in integrated circuits provides significant improvement in signal to noise ratio over conventional detection configurations. The method and device can be used for failure analysis and testing of advanced technology IC chips for which high sensitivity in modulation mapping is required.

Various approaches can be used to interrogate a surface such as a surface of a layered semiconductor structure on a semiconductor wafer. Certain approaches employ Second Harmonic Generation while other utilize four wave-mixing or multi-wave mixing. Corona discharge may be applied to the sample to provide additional information. Some approaches involve determining current flow from a sample illuminated with radiation.