The contribution of HfO/sub 2/ bulk oxide traps to dynamic NBTI in pMOSFETs

The negative bias temperature instability (NBTI) under pulsed bias stress conditions of devices with HfO/sub 2/ and SiO/sub 2/ gate dielectrics are studied and compared. The pulsed stress frequency responses of threshold voltage shift (/spl Delta/V/sub th/) are quite different for both dielectrics as well as the acceleration parameters. The presence of bulk traps in the HfO/sub 2/ film is used to explain these differences. Furthermore, it is shown that caution must be taken when extrapolating the device lifetime of HfO/sub 2/ gate dielectrics.