Experimental evidence of interface state generation due to the emission of leakage electrons from the silicon substrate into SiO2is presented. Interface states were measured on MNOS capacitors before and after temperature‐bias stress, where the electron emission process occurred, using the high‐frequency and quasistaticC‐Vtechnique. Electrical access to the silicon surface to vary the space‐charge width was made by the use of a very small diffusion underneath the field plate. The generation of interface states which can in turn cause device degradation is undoubtedly a reliability concern.