Single Events in a COTS Soft-Error Free SRAM at Low Bias Voltage Induced by 15-MeV Neutrons

Abstract

This paper presents an experimental study of the sensitivity to 15-MeV neutrons of Advanced Low Power SRAMs (A-LPSRAM) at low bias voltage little above the threshold value that allows the retention of data. This family of memories is characterized by a 3D structure to minimize the area penalty and to cope with latchups, as well as by the presence of integrated capacitors to hinder the occurrence of single event upsets. In low voltage static tests, classical single event upsets were a minor source of errors, but other unexpected phenomena such as clusters of bitflips and hard errors turned out to be the origin of hundreds of bitflips. Besides, errors were not observed in dynamic tests at nominal voltage. This behavior is clearly different than that of standard bulk CMOS SRAMs, where thousands of errors have been reported.

SEU Characterization of Three Successive Generations of COTS SRAMs at Ultralow Bias Voltage to 14.2-MeV Neutrons

“…Both the microcontroller and the SRAM were biased by two independent power supplies, which made possible to tune that of the SRAM from 0 to 3.15V. More details about the test infrastructure can be found in [9] and [10].…”

“…However, little work was carried out in COTS devices. In [9] and [10], the authors studied the sensitivity of COTS Advanced Low Power SRAMs (A-LPSRAMs) and CMOS SRAMs, manufactured in 150-nm and 90-nm technologies respectively, at 0.5 V -3.3 V.…”

SEU characterization of commercial and custom-designed SRAMs based on 90 nm technology and below

“…Previous studies have pointed out the relationship between the bias voltage reduction and the sensitivity against SEEs in different technologies of SRAMs [8], [9]. In [10], the authors studied the sensitivity against 15-MeV neutrons of a COTS Advanced Low Power SRAMs (A-LPSRAM), manufactured in 150-nm CMOS technology, at 0.5V -3.3V. However, to the authors' knowledge, little work has been carried out on COTS SRAMs at ultra-low bias voltages under natural radiation: cosmic rays or α emitter impurities.…”