Stress induced irregular tunneling current and interface trap characteristics were observed in non-planar substrate metal-oxide-semiconductor (MOS) capacitors. The oxide electric field distributions in the concave and convex corner regions of non-planar structure are different. After stressing, the inversion tunneling current was observed to decrease gradually in non-planar sample but decrease then increase in planar one. Moreover, the non-planar sample exhibits two peaks phenomenon in interface capacitance (C-it) after stress which is different from planar one with one peak. A model describing the role of deep depletion (DD) for sample with different treatments is also proposed for the observation. (C) 2013 Elsevier Ltd. All rights reserved.