This paper demonstrates a differential dual-phase interferometric imaging method in which the reflected probe beam modulated weakly by the charge carriers is mixed separately with two reference beams with a known phase shift in between. Performing a balanced detection scheme on these two channels, the common-mode-noise associated with strong DC background and its noise can be significantly reduced. The performance of the interferometric technique is systematically compared with the conventional mapping method through investigating inverter chains on two test chips of 180nm bulk silicon technology and 32nm SOI technology. The future work will focus on adapting the method for GHz frequency regime and time-domain implementation of the method. The method will find applications in failure analysis and testing of advanced technology IC chips for which the high sensitivity in modulation mapping is required.

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