Study of Secondary Scattering/Albedo Neutron Fields and Their Impacts on SER as Function of Scene Topologies

This article describes a series of experimental measurements and calculations designed to quantify the scattering and albedo effects on neutron spectra and their consequences on single-event effect (SEE) sensitivities. An experimental approach was proposed to investigate the scattering and albedo neutron spectra using a
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Cf facility and for several scene topologies. A highly sensitive neutron spectrometer based on a Bonner sphere system (BSS) is used, allowing to measure neutron energy from thermal to tens of megaelectron-volts. To complete previous SEE measurements on 45 nm, the soft error rate (SER) was recorded on 28-nm technology. A second part considers complex topologies including concrete walls and high-density polyethylene (HDPE) blocks to represent a design facility and the shielding to protect some parts of the SEE test board, respectively. The results showed that devices are more impacted by the presence of materials, especially HDPE. Indeed, almost 25% of the events are due to the secondary neutrons. Orders of magnitude are not critical, nevertheless, they warn about taking into account the albedo contributions and how to add materials in the vicinity of measurement devices.