A Terrestrial SER Estimation Methodology based on Simulation coupled with One-Time Neutron Irradiation Testing

電子機器の信頼性評価の迅速化に光明 --様々な中性子施設で半導体ソフトエラー評価を可能にする技術を開発--. 京都大学プレスリリース. 2023-06-08.Terrestrial soft error rates (SERs) are generally estimated by performing an experiment using spallation neutron beam with the energy spectrum being similar to that of the terrestrial neutrons or at least four measurements using various (quasi-)mono-energetic neutron and/or proton sources to determine the parameters of the Weibull function. We here propose a method to estimate the terrestrial SERs based on simulation coupled with one-time neutron irradiation testing which can be applied to various kinds of neutron sources. In this method, the dependences of single event upset (SEU) cross sections on the neutron energy and the critical charge are calculated by simulation using Particle and Heavy Ion Transport code System (PHITS). The critical charge is used as the only calibration parameter, which is adjusted to reproduce the SER measured by one-time neutron irradiation. The validity of our method is investigated for 65-nm bulk SRAMs with the measured data using various neutron sources in Japan. Our method generally provides the reasonable terrestrial SERs compared with those obtained by the Weibull function method. This result indicates the feasibility of evaluating the terrestrial SER using one of the various neutron sources available all over the world, including those not dedicated to SER measurement. We also investigate the necessity of the elaborated geometry of device under test (DUT) for the accuracy of the simulation. It is shown that detailed material compositions of DUT are not necessary in our method except when the one-time irradiation is performed using the neutron source that contains a high-quantity of low-energy neutrons below 8 MeV. Furthermore, we confirm that the configuration of the sensitive volume can be simplified without sacrificing the estimation accuracy. These simplifications in the simulation help to reduce the modeling and calculation cost in SER estimation

Investigation of irradiation effects on highly integrated leading-edge electronic components of diagnostics and control systems for LHD deuterium operation

High-temperature and high-density plasmas are achieved by means of real-time control, fast diagnostic, and high-power heating systems. Those systems are precisely controlled via highly integrated electronic components, but can be seriously affected by radiation damage. Therefore, the effects of irradiation on currently used electronic components should be investigated for the control and measurement of Large Helical Device (LHD) deuterium plasmas. For the precise estimation of the radiation field in the LHD torus hall, the MCNP6 code is used with the cross-section library ENDF B-VI. The geometry is modeled on the computer-aided design. The dose on silicon, which is a major ingredient of electronic components, over nine years of LHD deuterium operation shows that the gamma-ray contribution is dominant. Neutron irradiation tests were performed in the OKTAVIAN at Osaka University and the Fast Neutron Laboratory at Tohoku University. Gamma-ray irradiation tests were performed at the Nagoya University Cobalt-60 irradiation facility. We found that there are ethernet connection failures of programmable logic controller (PLC) modules due to neutron irradiation with a neutron flux of 3  ×  106 cm−2 s−1. This neutron flux is equivalent to that expected at basement level in the LHD torus hall without a neutron shield. Most modules of the PLC are broken around a gamma-ray dose of 100 Gy. This is comparable with the dose in the LHD torus hall over nine years. If we consider the dose only, these components may survive more than nine years. For the safety of the LHD operation, the electronic components in the torus hall have been rearranged

Characteristic Charge Collection Mechanism Observed in FinFET SRAM cells

The single event effects (SEEs) characteristics on 14/16-nm bulk Fin Field-Effect Transistors (FinFETs) were investigated in terms of single bit upsets (SBUs) and multiple cell upsets (MCUs). The sensitive area estimation based on the cross-section are also discussed