Estimation of interface roughness using tunneling current in ultrathin MOSFET

Interface roughness effects on tunneling current in ultrathin MOS structures are investigated theoretically. The roughness at SiO2/Si interface is described in terms of Gauss distribution. It is shown that the effects of rough surface on tunneling current can not be neglected while tunneling occurs. The effect of rms (root-mean-square) roughness on the direct tunneling current decreases with the applied voltage increasing and increases with rms roughness increasing and the effects increase exponentially with oxide thickness or applied voltage decreasing, The applied voltage shift at the extreme of current oscillations increases linearly with SiO2/Si interface roughness increasing. The amplitudes of current oscillations in ultrathin gate oxides are shown to decrease much with SiO2/Si interface roughness increasing. The factor of attenuation amplitudes increases exponentially with SiO2/Si interface roughness increasing. This means that this shift may be used to obtain the information about die interface roughness as an inexpensive and simple tool.Engineering, Electrical & ElectronicMaterials Science, MultidisciplinaryPhysics, AppliedPhysics, Condensed MatterCPCI-S(ISTP)