Обобщённая TCAD-модель для учёта радиационных эффектов в структурах МОП и биполярных транзисторов
For the correct accounting of joint effects of radiation and temperature on characteristics of MOSFETs with the help of TCAD system the nonlinear correction coefficient which considers change of concentration of traps from temperature is entered into model of traps volume density in oxide.
The main content of the training manual is:consideration of the issues of the effect of radiation creating structural defects on the main parameters of bipolar transistors, Consider issues related to the influence of ionization factors on the operation of transistors (radiation transients), the effect of nuclear reactions and fast annealing on the parameters of transistors is considered; Classification of radiation effects in bipolar transistors is given.
Quasi-3D model for calculation of radiation leakage currents in modern submicron SOI MOSFET structures is proposed. Instead of the fully 3D modeling is proposed to solve two tasks: 2D modeling of the traditional MOSFET cross-section and 3D modeling of the side parasitic transistor. The radiation-induced leakage current simulation in the 0.35 μm SOI MOSFET structure with taking account ionizing radiation with a dose of up to 500 krad was simulated. The results of the simulation show that in comparison with the traditional fully 3D modeling, which requires 11 hours of computer time, the computer time for the IdVg characteristic was reduced to 71 minutes (i.e. the computer time decreased by 9 times).
The effects of proton irradiation on SiGe heterojunction bipolar transistor (HBT) are investigated using Synopsys/ISE TCAD tool. To account for the impact of proton irradiation models for carrier lifetime degradation under irradiation are included in the program. The results of modeling the impact of protons of different energies are presented. For SiGe HBT increase in the base current for low-energy protons is more intense than for high-energy protons. We also present the simulation results of SiGe HBT dc and ac performance after proton exposure. The simulation results are in good agreement with experimental data.
The effects of neutron irradiation on both Si bipolar junction transistor (BJT) and SiGe heterojunction transistor (HBT) are investigated using Synopsys TCAD tool. The carrier lifetime degradation under irradiation models are included in the program. For SiGe HBT at fluences as high as 10**15 cm-2 the degradation of peak current gain is less than 40%, and the device maintains a peak current gain of 80 100 after 10**15 cm-2. The simulation results are in good agreement with experimental data.
An EKV-RAD macromodel for SOI/SOS MOSFET with account for radiation effects is developed using a subcircuit approach. As an addition to the standard version of the EKV model 1) radiation dependencies of parameters VTO, GAMMA, KP, E0 are introduced and 2) additional circuit elements to account for floating-body effects and radiation-induced leakage currents under static and dynamic radiation influence are connected. Maximum simulation error is 5–7% in the dose range up to 1 Mrad. It is shown that EKV-RAD spends less CPU time by 15–30% for analog and 40–50% for digital SOI/SOS CMOS circuits simulations compared to BSIMSOI-RAD model.