Comprehensive Thickness-Dependent Power-Law of Breakdown in CMOS Gate Oxides

The voltage acceleration of breakdown changes from the I/E rule to the power law when the gate voltage (absolute value) decreases below some threshold voltage irrespectively of the type of MOS transistors and polarity of the voltages. The exponent of all the cases decreases when the gate insulator thickness is reduced below the threshold that depends on the type of MOS transistors. There is little polarity difference in the exponents of PMOS. By contrast the exponent of NMOS under inversion is much larger than the others. The fact might be related to the absence of the hole valence band tunneling and suggests the hole involvement in the breakdown events