Impurity redistribution during thermal oxidation in then‐channel transistor of SOS/CMOS can result in an inversion of silicon material type (frompton) along the island edge and extending from drain to source. This inverted island edge produces excessive drain‐to‐source current leakage. We show that the electron‐beam‐induced‐current (EBIC) mode of operation in the scanning electron microscope (SEM) is an effective method of observing inverted island edges.