Keita Nakano

Negative and Positive Muon-Induced Single Event Upsets in 65-nm UTBB SOI SRAMs

We have performed an irradiation test of low-energy positive and negative muons on 65-nm ultra-thin body and thin buried oxide silicon-on-insulator static random access memories. The single event upset (SEU) cross sections were measured systematically as a function of incident muon momentum and operating supply voltage. The experimental results show that the negative muon SEUs occur at about three times higher rate than the positive muon ones at the supply voltage of 0.5 V when the incident muons stop near the sensitive volume (SV). A Monte-Carlo simulation with the particle and heavy ion transport code system (PHITS) was carried out using a simple SV model. The simulation based on the PHITS using the SV model is found to reproduce generally well the momentum dependence of the measured SEU cross sections for both positive and negative muons. From the simulation, the charged particles and secondary ions having significant influence on SEUs are specified and the differences between negative and positive muons are discussed.

Measurement and Mechanism Investigation of Negative and Positive Muon-Induced Upsets in 65-nm Bulk SRAMs

Irradiation experiments of positive and negative muon were conducted for 65-nm bulk CMOS static random-access memory. The experimental results reveal that parasitic bipolar action (PBA) contributes to negative muon-induced upsets. We observe an increase in single event upset (SEU) cross section at higher operation voltage under negative muon irradiation while positive muon shows an opposite decreasing tendency. Also, the proportion of multiple-cell upset (MCU) events to all the negative muon-induced upset events is up to 66, and more than a 20-bit MCU is observed. Furthermore, Monte Carlo simulation of particle and heavy ion transport code system (PHITS) is performed for explaining the difference in SEU between positive and negative muons. We also discuss the charge threshold that triggers PBA-induced MCU using measurement and simulation results with different momentum muons. The estimated threshold is much larger than the charge that the positive muons can deposit, which well explains that no PBA-induced MCUs are observed under positive muon irradiation.