Heavy Ion Irradiation Fluence Dependence for Single-Event Upsets in a NAND Flash Memory

Abstract

NAND Flash memories are currently the dominant mass storage technology in the commercial market, and they are finding their way into space systems thanks to the technology's high density and low cost [1]. NASA and other government agencies as well as academia have actively investigated the radiation susceptibility of each generation of NAND flash from various commercial vendors, including the Micron and Samsung [2]−[4]. The growing complexity of the device's control circuits as well as the continued shrinking of the memory cell area have introduced new challenges for radiation testing. Existing single-event effect (SEE) test standards include the JESD57, ASTM F1192, and ESCC No. 25100 [5]−[7]. These test standards provide top level guidance for single-event testing in general. NASA has recently published a more detailed test guideline targeted specifically at current nonvolatile memories [8]. However, the current test methodologies need to be continuously updated with test findings.For example, the traditional test protocols are predicated on the assumption that the SEE cross section remains constant with fluence. So the device upset rate in space is constant over time. Therefore, typical heavy ion tests demand a fluence high enough to cover a representative portion of the device sensitive regions. In this investigation, we observed the cross section varies inversely with the test fluence, which we attribute to the range of upset sensitivities of the memory cells.

Heavy Ion and Proton-Induced Single Event Upset Characteristics of a 3-D NAND Flash Memory

“…In a previous study, we found that the Micron 128 Gb planar NAND exhibited an inverse fluence dependence for the SEU cross section [20], where the cross section decreased with increasing fluence. We believed that the phenomenon is possible for any high-density device with a variable upset threshold distribution.…”

“…The authors alluded to the introduction of devices with multiple storage levels in the future, which they speculated could introduce further complexity to the radiation response. In fact, more recent studies have shown that SEU susceptibility can be substantial in multiple-level cell (MLC) or triple-level cell (TLC) devices [18], [20]. The results illustrate how the technological progress can impact radiation effects.…”

“…Therefore, it is critical to understand the susceptibility of the latest commercial flash memories against the relevant radiation environments and radiation effects, including but not limited to total-ionizing dose (TID), and heavy ion and proton-induced single-event effects (SEE). The radiation effects community has investigated each generation of flash technology [2]− [20]. These investigations included testing for feasibility of specific flight missions [2]- [6], research done by academic institutions [7]− [11], and technology evaluations performed by NASA, ESA, and other aerospace industries [12]− [20].…”

“…The radiation effects community has investigated each generation of flash technology [2]− [20]. These investigations included testing for feasibility of specific flight missions [2]- [6], research done by academic institutions [7]− [11], and technology evaluations performed by NASA, ESA, and other aerospace industries [12]− [20]. Notably, the publications on this topic included an early paper in 1997 on a 16 Mbit NOR and a NAND flash [19].…”

“…Notably, the publications on this topic included an early paper in 1997 on a 16 Mbit NOR and a NAND flash [19]. One of the latest publications in 2016 evaluated a 128 Gb planar NAND flash [20]. The devices in the 1997 study were robust against heavy ion-induced singleevent upset (SEU).…”