# Study on Single-Event Transient Hardness of Semi-Enclosed Gate NMOS
## 2 Simulation Setup  
In this simulation, the Sentaurus TCAD simulation software(TCAD 2017) was employed, utilizing a three-dimensional numerical simulation approach to investigate the SEE in a semi-enclosed gate NMOS transistor based on a 55 nm bulk silicon process. The device modeling diagram and material doping data are shown in Figure 1 and Table 1, respectively. This method allows for the acquisition of the electrical response of the device under particle incidence conditions, thereby enabling the analysis of the sensitivity and mechanisms of SET. By simulating the impact of heavy ions on the semi-enclosed gate NMOS transistor, this study aims to provide detailed insights into the internal electric field and potential changes along the particle trajectory, as well as the variations in charge collection efficiency and pulse width. These results will contribute to a deeper understanding of the SET mechanisms in semi-enclosed gate structures and offer valuable guidance for the design of radiation-hardened integrated circuits in advanced technology nodes. After modeling the semi-enclosed gate NMOS transistor, calibration of the I-V (current-voltage) characteristic curve is required. During the calibration, the Vg-Id curve of a conventional NMOS transistor is used as a reference. Due to structural differences between the devices, the calibration is considered successful as long as the increasing trends of their current-voltage (I-V) characteristics exhibit similarity. Differences in the slopes can be tolerated. The calibration curve is illustrated in Figure 2. The calibrated model is capable of more precisely predicting the impact of single event effects on the performance of the semi-enclosed gate NMOS device. Research has found that the morphology and distribution density of the ionization track directly affect the charge collection efficiency and the severity of SEEs [30; 31; 32; 33]. This study aims to conduct s analysis with traditional NMOS transistors and, by simulating ionization tracks under different incident conditions, focuses on investigating how the physical effects generated after particle incidence influence the transient response of the device. The findings are expected to contribute to formulating more effective strategies for mitigating SEE in advanced semiconductor devices, particularly in radiation-prone environments. In the SET simulation, the carrier concentration is modeled using the Fermi distribution. The physical model for carrier concentration comprehensively considers the bandgap narrowing effect in highly doped semiconductors. The non-equilibrium carrier generation-recombination model encompasses Shockley indirect recombination, radiative \begin{table}
\begin{tabular}{c c c} \hline \hline
**Part** & **Material (or Element)** & **Size (or Concentration)** \\ \hline Gate & Polysilicon & \(55\) nm \\ Source/Drain Doping & As & \(2\times 10^{20}\) cm\({}^{-3}\) \\ Spacer & Si\({}_{3}\)N\({}_{4}\) & \(10\) nm \\ Gate Oxide & SiO\({}_{2}\) & \(1\) nm \\ Channel Doping & B & \(8.5\times 10^{17}\) cm\({}^{-3}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Modeling parameters of the semi-enclosed gate NMOS device. Figure 1: Three-dimensional diagram of a semi-enclosed gate NMOS device. Figure 2: Calibration of Id-Vg characteristics for conventional NMOS and semi-enclosed gate NMOS. recombination, and Auger recombination mechanisms, whose dependence on carrier concentration directly influences carrier lifetime. The carrier mobility model incorporates ionized impurity scattering, surface scattering, and carrier-carrier scattering. The impact ionization model adopts the Selberherr impact ionization model, which characterizes carrier multiplication phenomena through electric field-dependent impact ionization coefficients. This simulation study first conducted heavy ion bombardment simulations on semi-enclosed gate NMOS and conventional NMOS under identical conditions, analyzing transient differences in drain current and temporal variation of drain charge.