Hot-Carrier Degradation (HCD) is an effect related to the damage produced by carriers of sufficient high kinetic energy (hot carriers). The defects formed by HCD are responsible for a change in the linear drain current or for a shift in the threshold voltage of MOSFETs. The current model is based on the assumption that the origin of HCD is related to the dissociation of Silicon-Hydrogen bonds, thereby resulting in a so-called "dangling bond". These dangling bonds can capture carriers, thus producing a charged defect, which perturbs the electrostatics of a device and degrades the mobility. HCD is a great reliability issue and its understanding is crucial for predicting and improving the device lifetime.
In the current version of the model we consider only the excitation of the H atom from either the ground or the top bonded level of the truncated harmonic oscillator which represents the bond (figure 1). These processes are referred to as the Single- and Multiple-Particle mechanisms (SP- and MP-processes) of the bond rapture. So far these two dissociation modes have been considered as semi-independent, and the corresponding concentration of interface states was found as a superposition of SP- and MP-related concentrations. Such a simplified treatment appears to be unphysical because these processes are just different pathways of the same dissociation reaction. Instead, one should consider these processes as concurrent competing processes. Moreover, contributions also from intermediate states of the oscillator are expected to be significant and therefore have also been included into the rate equation system.
Hence the model will be extended in a manner to incorporate the hydrogen release from all the states as well as the reverse passivation reaction rates. These forward and reverse processes will be treated simultaneously as competing pathways of the same chemical reaction (figure 2). These extended HCD models will be implemented into our new simulator ViennaSHE, which calculates a deterministic solution of the Boltzmann transport equation. On the basis of ViennaSHE the model will be validated in order to represent the characteristics of the degraded devices. For this purpose, ultra-scaled devices with a channel length of less than 100nm will be employed.