B. Sagnes

Device simulation study of the SEU sensitivity of SRAMs to internal ion tracks generated by nuclear reactions

Single-event upsets (SEUs) in static random access memories (SRAMs) are investigated using three-dimensional (3-D) full cell device simulations for tracks that do not cross the OFF n-channel MOSFET drain. These tracks are representative of the most probable geometrical cases when the ions are generated inside the device by nuclear reactions, and then address one important part of neutron- or protons-induced soft errors. It is found that the duration and magnitude of the ion-induced current pulse strongly depends on the track location. As a result, the flipping of the memory cell is delayed, and the critical charge involved during the upset is no longer constant. A linear relationship between the critical charge and the delay is found and is explained by the contribution of the ON p-channel MOSFET. The increase of the ion current pulse delay and broadening when the track is moved away from the drain is explained on the basis of the diffusion-collection mechanism. Indications on the size of the sensitive regions are derived.

Criterion for SEU occurrence in SRAM deduced from circuit and device Simulations in case of neutron-induced SER

A reliable criterion for SEU occurrence simulation is presented. It expresses the relationship existing at threshold between the magnitude and duration of the ion-induced parasitic pulse. This criterion can be obtained by both three-dimensional device and SPICE simulations. Using this criterion, the simulated and experimental SER on 130 and 250 nm technologies are shown to be in good agreement.

Neutron-induced SEU in bulk SRAMs in terrestrial environment: Simulations and experiments

This work investigates the sensitivity of bulk technologies in the terrestrial neutron environment as a function of technology scaling. Their sensitivity is analyzed with both experiments and Monte Carlo simulations. The soft error rate (SER) of future technology generations is extrapolated, analyzed and discussed on the basis of different parameters such as the interaction volume, the secondary ion species and the incident neutron energy ranges.

Study of basic mechanisms induced by an ionizing particle on simple structures

The currents induced by an ionizing particle in a diode and a bar are compared. A short track, located within the structure, and a long track passing through it are considered. Analysis of the mechanisms involved is proposed to explain why the observed effects are approximately the same.

Monte-Carlo simulations to quantify neutron-induced multiple bit upsets in advanced SRAMs

This paper presents a new 3D methodology to simulate Multiple Bit Upsets in commercial SRAMs. Experiments are performed at the Los Alamos neutron facility on 90, 130, and 250 nm SRAMs and compared to Monte-Carlo simulations. A discussion on ions inducing MBUs is also proposed.

Prediction of Multiple Cell Upset Induced by Heavy Ions in a 90 nm Bulk SRAM

The PHISco simulation tool was known to be able to predict the SEU cross section for incident ions. This tool is improved in this work to also predict the MCU rate. Experimental and predicted results are shown to be in good agreement on a 90 nm bulk SRAM. The simulated SRAM structure includes the N-well, which is known to be a barrier to the charge carriers.

Effects of beam spot size on the correlation between laser and heavy ion SEU testing

This work presents new results to compare EADS CCR laser experiments and heavy ion tests. More precisely, this study describes the influence of the laser spot size on the threshold energy of the SEU cross-section curves. A new methodology is proposed to correlate laser to heavy ion results.

Innovative Simulations of Heavy Ion Cross Sections in 130 nm CMOS SRAM

A simulation tool to predict the heavy ion cross section is proposed. A 20% average error between experimental and simulated results is shown for a SRAM in a commercial 130 nm CMOS technology. Input parameters are obtained by device or circuit simulations and no fitting parameters or empirical calibration with previous radiation testings is needed.

Neutron-induced SEU in SRAMs: Simulations with n-Si and n-O interactions

This paper investigates the sensitivity of SOI and Bulk SRAMs to neutron irradiations with energies from 14 to 500 MeV. The technology sensitivity is analyzed with both experiments and Monte Carlo simulations. In particular, simulations include the nuclear interactions of neutrons with both silicon and oxygen nuclei (n-Si and n-O), in order to investigate the influence of isolation upper layers on the device sensitivity. The device cross-sections are analyzed for mono-energetic neutron irradiations and discussed in terms of nuclear interaction type (n-Si and n-O) and distribution of the secondary ion recoils. We also investigate the dimensions of the interaction volume around the sensitive cell as a function of the device architecture.

Study of the Thermal Behavior of the OSL Integrated Sensor Response

Temperature irradiation is shown to cause the fading of the OSL signal. The temperature dependence is modeled using an Arrhenius law. A simple method is proposed to correct this effect a posteriori.