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A major challenge for replacing gate SiON with HfO2 is the instability and reliability of HfO2. Unlike the SiON, there can be substantial amount of as-grown electron traps in HfO2. These traps can cause instability in the threshold voltage and contribute to the dielectric breakdown. Despite the early efforts, our understanding of them is incomplete. Agreement on their capture cross sections has not been reached and the reported values spread in a large range of 10−12–10−19cm2. The objective of this paper is to determine their capture cross sections unambiguously, which requires knowing the gate current and the electron fluency for filling the trap. A key part of this work is to estimate the trapping-induced transient gate current following the application of a pulse to the gate. This is achieved by numerical simulation. It is found that trapping can reduce the gate current by two orders of magnitude and the gate current can drop substantially within microseconds. The results show the presence of two distinctive capture cross sections in the order of 10−14 and 10−16cm2, respectively, which most likely originated from two different types of as-grown electron traps in HfO2. These capture cross sections are insensitive to fabrication and processing techniques.

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during the measurement. To obtain the degradation-free gm, pulsed Id-Vg with a transition time of 6 gs must be used. Lifetime of pMOSFETs is limited by negative bias Fig. 3 also shows that gm actually increases with time temperature instability (NBTI). For the first time, we show under a constant Vgst. This is caused by a reduction of lVgstthat the NBTI-induced threshold voltage shift, AVth, Vthl, which enhances the effective mobility, despite the measured in early works by using either the 'on-the-fly' or the degradation of low-field mobility. A more detailed analysis conventional transfer characteristics extrapolation techniques on the variation of effective mobility during stress was given is not the real AVth under practical operation. A new method in our recent work [7]. After using the degradation-free Id and is proposed for estimating the real AVth.gm, Fig. 4 shows that the AVth(OTF) is more than doubled.However, we will demonstrate that AVth(OTF) is not