Possible effects on avionics induced by terrestrial gamma-ray flashes

Abstract. Terrestrial gamma-ray flashes (TGFs) are impulsive (intrinsically sub-millisecond) events associated with lightning in powerful thunderstorms. TGFs turn out to be very powerful natural accelerators known to accelerate particles and generate radiation up to hundreds of MeV energies. The number ratio of TGFs over normal lightning has been measured in tropical regions to be near 10−4. We address in this Article the issue of the possible susceptibility of typical aircraft electronics exposed to TGF particle, gamma ray and neutron irradiation. We consider possible scenarios regarding the intensity, the duration, and geometry of TGFs influencing nearby aircraft, and study their effects on electronic equipment. We calculate, for different assumptions, the total dose and the dose-rate, and estimate single-event-effects. We find that in addition to the electromagnetic component (electrons/positrons, gamma rays) also secondary neutrons produced by gamma-ray photo production in the aircraft structure substantially contribute to single-event effects in critical semiconductors components. Depending on the physical characteristics and geometry, TGFs may deliver a large flux of neutrons within a few milliseconds in an aircraft. This flux is calculated to be orders of magnitude larger than the natural cosmic-ray background, and may constitute a serious hazard to aircraft electronic equipment. We present a series of numerical simulations supporting our conclusions. Our results suggest the necessity of dedicated measurement campaigns addressing the radiative and particle environment of aircraft near or within thunderstorms

Present and Future Non-volatile Memories for Space

We discuss non-volatile memories (NVM) for space applications. The focus will be both on technologies and devices aimed at the mainstream commercial markets and on rad-hard devices. Commercial NVMs are very attractive for space designers due to their large size (tens of Gbits), even though they have several issues related to ionizing radiation. Rad-hard NVMs offer radiation hardness, but are available only in small size (few Mbits). Most of the emphasis in this review paper will be on the current dominant technology in the mainstream market: floating gate flash memories. A comprehensive discussion of total dose and single event effects results for a wide cross section of NVMs will be presented. Finally, we will conclude with a cursory glance at other emerging non-volatile technologies

Retention Errors in 65-nm Floating Gate Cells After Exposure to Heavy Ions

The retention of floating gate cells is studied up to one year after heavy-ion exposure, without using accelerated tests. Cross-sections of retention errors and threshold voltage shifts are discussed and compared with previous generation devices. The dependence of retention errors on the program level and irradiation angle is discussed and the underlying mechanisms are examined

Impact of Fowler-Nordheim and channel hot carrier stresses on MOSFETs with 2.2nm gate oxide

We studied the degradation of NMOSFETs with 2.2mn gate oxide subjected to Fowler-Nordheim and channel hot carrier stresses. We highlighted the differences between the two types of stresses, in particular concerning the behavior of the gate current. Before hard breakdown, Fowler-Nordheim stressed devices showed pre-breakdown and/or soft-breakdown, while progressive breakdown was much more common with channel hot carrier stresses, especially at V-gs = V-ds/2. The impact of the stresses on the transfer and output characteristics of the devices was then considered. Finally, the effect of the degradation on adjacent, nominally identical MOSFETs was studied, showing potential issues for circuits that rely on matching

Electrostatic discharge effects in ultrathin gate oxide MOSFETs

The effects of destructive and nondestructive electrostatic discharge (ESD) events applied either to the gate or drain terminal of MOSFETs with ultrathin gate oxide, emulating the occurrence of an ESD event at the input or output IC pins, respectively, were investigated. The authors studied how ESD may affect MOSFET reliability in terms of time-to-breakdown (TTBD) of the gate oxide and degradation of the transistor electrical characteristics under subsequent electrical stresses. The main results of this paper demonstrate that ESD stresses may modify the MOSFET current driving capability immediately after stress and during subsequent accelerated stresses but do not affect the TTBD distributions. The damage introduced by ESD in MOSFETs increases when the gate oxide thickness is reduced

Impact of Technology Scaling on the Heavy-Ion Upset Cross Section of Multi-Level Floating Gate Cells

The corruption of the information stored in floating gate cells due to heavy-ion strikes is a critical issue for the use of Flash memories in space. In this work we examine how feature size scaling affects the single event upset sensitivity of multi-level floating gate cells with NAND architecture. Both experimental data on heavy-ion irradiation and analytical modeling are used to study how the threshold LET and saturation cross section depend on the cell feature size. A comparison is also carried out between multilevel and single-level floating gate cells