Copper-related degradation of SiO2 in metal-oxide-semiconductor capacitors subjected to bias thermal stress:: Leakage of the minority charge carriers in the inversion layer

We describe a mechanism of Cu-related degradation of SiO2 in metal-oxide-semiconductor capacitors subjected to bias thermal stress (BTS). The commonly used stress of bias larger than 1 MV/cm at 300degreesC results in increased oxide conductivity, which is large enough to enable the leakage of minority carrier charge generated at the inversion layer, while the oxide capacitance and high-frequency deep depletion capacitance can still be accurately measured. This is an intermediate degradation between the commonly reported flat-band voltage shifts and decrease in the breakdown voltage of the oxide. This phenomenon does not occur following BTS when the metallization is Al, or following thermal stress, even in Cu. (C) 2004 American Institute of Physics.