Enhanced Negative-Bias-Temperature Instability of P-Channel Metal-Oxide-Semiconductor Transistors due to Plasma Charging Damage

The effects of plasma charging on the negative-bias-temperature instability (NBTI) of p-channel MOS transistors were explored. The threshold voltage shift during bias-temperature stressing (BTS) could be enhanced by plasma charging damage. Authors also found that electron trappings are aggravated by plasma charging, even on new devices with large antenna area ratios prior to BTS. Charge pumping current measurements confirm that the interface-state density is increased for devices with large antennas, both before and after the BTS. This indicates that electron trapping is responsible for the observed low (in absolute value) threshold voltage in new devices with large antennas. It is proposed that the NBTI characterization can be used as a sensitive method for characterizing the antenna effects in devices with ultrathin gate oxide. 13 refs.