We present a physics-based hot-carrier degradation (HCD) model and validate it against measurement data on SiON n-channel MOSFETs of various channel lengths, from ultrascaled to long-channel transistors. The HCD model is capable of representing HCD in all these transistors stressed under different conditions using a unique set of model parameters. The degradation is modeled as a dissociation of Si-H bonds induced by two competing processes. It can be triggered by solitary highly energetical charge carriers or by excitation of multiple vibrational modes of the bond. In addition, we show that the influence of electron-electron scattering (EES), the dipolefield interaction, and the dispersion of the Si-H bond energy are crucial for understanding and modeling HCD. All model ingredients are considered on the basis of a deterministic Boltzmann transport equation solver, which serves as the transport kernel of a physics-based HCD model. Using this model, we analyze the role of each ingredient and show that EES may only be neglected in long-channel transistors, but is essential in ultrascaled devices.

It is well-established that oxide defects adversely affect functionality and reliability of a wide range of microelectronic devices. In semiconductor-insulator systems, insulator defects can capture or emit charge carriers from/to the semiconductor. These defects feature several stable configurations, which may have profound implications for the rates of the charge capture and emission processes. Recently, these complex capture/emission events have been investigated experimentally in considerable detail in Si/SiO2 devices, but their theoretical understanding still remains vague. In this paper we discuss in detail how the capture/emission processes can be simulated using the theoretical methods developed for calculating rates of charge transfer reactions between molecules and in electro-chemistry. By employing this theoretical framework we link the atomistic defect configurations to known trapping model parameters (e.g. trap levels) as well as measured capture/emission times in Si/SiO2 devices. Using density functional theory (DFT) calculations, we investigate possible atomistic configurations for various defects in amorphous (a)-SiO2 implicated in being involved in the degradation of microelectronic devices. These include the oxygen vacancy and hydrogen bridge as well as the recently proposed hydroxyl E center. In order to capture the effects of statistical defect-to-defect variations that are inevitably present in amorphous insulators, we analyze a large ensemble of defects both experimentally and theoretically. This large-scale investigation allows us to prioritize the candidates from our defect list based on their trap parameter distributions. For example, we can rule out the E center as a possible candidate. In addition, we establish realistic ranges for the trap parameters, which are useful for model calibration and increase the credibility of simulation results by avoiding artificial solutions. Furthermore, we address the effect of nuclear tunneling, which is involved according to the theory of charge transfer reactions. Based on our DFT results, we demonstrate the impact of nuclear tunneling on the capture/emission process, including their temperature and field dependence, and also give estimates for this effect in Si/SiO2 devices.

We used density functional theory (DFT) calculations to model the interaction of hydrogen atoms and molecules with strained bonds and neutral oxygen vacancies in amorphous silica (a-SiO 2). The results demonstrate that the interaction of atomic hydrogen with strained Si-O bonds in defect-free a-SiO 2 networks results in the formation of two distinct defect structures, which are referred to as the [SiO 4 /H] 0 and the hydroxyl E center. To study the distribution of each defect's properties, up to 116 configurations of each center were calculated. We show that the hydroxyl E center can be thermodynamically stable in the neutral charge state. In order to understand the origins and reactions of this defect, different mechanisms of formation, passivation, and depassivation have been investigated. The interaction of H with a single-oxygen vacancy in a-SiO 2 was studied in 144 configurations, all resulting in the hydrogen bridge defect. The reaction of the hydrogen bridge defect with the second H atom is barrierless and fully passivates the O vacancy. The latter defect reacts with atomic H with a small barrier, restoring the hydrogen bridge defect. These results provide a better understanding of how atomic and molecular hydrogen can both passivate existing defects and create new electrically active defects in amorphous-silica matrices.

No abstract

Recent studies have clearly shown that oxide defects are more complicated than typically assumed in simple twostate models, which only consider a neutral and a charged state. In particular, oxide defects can be volatile, meaning that they can be deactivated and re-activated at the same site with the same properties. In addition, these defects can transform and change their properties. The details of all these processes are presently unknown and poorly characterized. Here we employ time-dependent defect spectroscopy (TDDS) to more closely study the changes occurring at the defect sites. Our findings suggest that these changes are ubiquitous and must be an essential aspect of our understanding of oxide defects. Using density-functionaltheory (DFT) calculations, we propose hydrogen-defect interactions consistent with our observations. Our results suggest that standard defect characterization methods, such as the analysis of random telegraph noise (RTN), will typically only provide a snapshot of the defect landscape which is subject to change anytime during device operation.