Reliability Concerns of Radiation Effects on Space Electronics

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Reliability Concerns of Radiation Effects on Space Electronics

ong>Reliabilityong> ong>Concernsong> ong>ofong> ong>Radiationong> ong>Effectsong>

on Space Electronics

Abstract—There is no space system in which radiation effects

can be neglected. Trapped electrons and protons in the Earth’s

radiation belt can lead sudden failure, and total dose can reduce

lifetime ong>ofong> the mission without a proper shielding. ong>Reliabilityong>

engineers should concern not only thermal, dynamical and

atmospheric circumstances ong>ofong> space but also harsh radiation.

In this review, space radiation is introduced, possible effects are

discussed, modeling and testing methods are evaluated for the

application on space electronics.

I. INTRODUCTION

Natural space environment is a difficult challenge for electronics.

Trapped particles in the Earth’s radiation belts, solar

flares and cosmic rays jeopardize the operation and causes to

critical performance gradually. Single event effect (SEE) can

flip the bits in digital element and lead spontaneous system

failure, and total induced dose (TID) can reduce the lifetime

ong>ofong> the system. The radiation level in space environment

depends on the altitude, latitude, longitude and the time. For

instance, The South Atlantic Anomaly (SAA) is the region

where Earth’s inner Van Allen radiation belt makes its closest

approach to the planet’s surface. The satellites passing through

SAA exposes significantly high total dose damage. Therefore,

the dose and characteristics ong>ofong> radiation that will affect a space

satellite are greatly dependent on the launch date, duration

and orbit altitude. The desire to increase performance and

lifetime ong>ofong> a space system requires critical simulations ong>ofong> the

environment, evaluations ong>ofong> the reactions ong>ofong> material within

the estimated space environment. This makes the radiation a

great concern for reliability engineers on space electronics.

Early evaluation ong>ofong> various radiation effects in the design ong>ofong>

systems is mandatory for orbit selection, mass budget, thermal

protection, and component selection policy.

II. RADIATION SOURCES

The particles associated with ionizing radiation are categorized

into three main groups relating to the source ong>ofong>

the radiation: solar flare particles, cosmic rays, and trapped

radiation belt particles.

A. Solar Flares

Solar flares are powerful explosions in the sun’s atmosphere,

which release enormous amounts ong>ofong> energy. Solar flare, which

is associated with coronal mass ejection, heats the plasma

and accelerates protons, neutrons and electrons to relativistic

speeds. The solar cycle, or the solar magnetic activity cycle,

˙Ilknur Baylako˘glu & Murat Hudaverdi

TUBITAK, Space Technologies Research Institute

ODTU, 06531, Ankara, Turkey

Email: ilknur.baylakoglu@uzay.tubitak.gov.tr

is ∼11 years. This is the main source ong>ofong> periodic solar

variation driving variations in space weather. A space mission

should be designed to survive at least one massive solar flare.

Although a cycle can be defined for solar activities, nobody

guaranties a precise prediction or solar particle events. NOAA-

Space Weather Prediction Center predicts The Solar Cycle 24

maximum will occur about October, 2011 for the large cycle

case and August, 2012 for the small cycle (see Figure 1).

Fig. 1. The ong>ofong>ficial Solar Cycle 24 prediction is for Sunspot Number (Credit:

NOAA/Space Weather Prediction Center).

B. Cosmic Rays

Cosmic rays are energetic quantum particles originating

from space that affect on Earth’s atmosphere. The majority

(about 90%) ong>ofong> all the incoming cosmic rays are protons,

about the rest (9%) are helium nuclei (alpha particles) and

about very few (1%) are electrons. The variety ong>ofong> particles

causes the wide variety ong>ofong> errors on space device, ICs or solar

panels.

C. Trapped ong>Radiationong> Belt

The turbulent motion ong>ofong> molten iron core, the Earth has

a strong magnetic field around. This field concentrates highenergy,

ionizing particles including electrons, protons, and

some heavier ions. The field mechanism traps these charged

particles within specific regions, called the Van Allen belts.


Fig. 2. Trapped particles spiral back and forth along magnetic field lines

(Credit: NOAA/SEE).

The Figure 2 shows the field lines which the trapped particles

travels back and forth along. Since the Earth’s dipolar field

displaced from the center, the radiation belts get very close

over the eastern coast ong>ofong> South America. This high particle

density region is called as the South Atlantic Anomaly (SAA).

Satellites at LEO experience a considerable natural shielding

from cosmic rays due to the Earths magnetic field.

III. RADIATION EFFECTS

High-energy particle or photon lose its kinetic energy in

different mechanisms, thus creating various damages.

A. Total Ionizing Dose (TID)

The first failure ong>ofong> TID goes back to early 1970s. The

Starfish nuclear weapon test in 1962 was held in an Johnston

Island in the Pacific Ocean. The particles were injected to

earth’s atmosphere, which formed a radiation belt at an altitude

ong>ofong> ∼400 km. For instance, Telstar satellite experienced a TID

100 times larger than expected. Within 7 months, the Starfish

nuclear weapon test destroyed seven satellites.

TID is the energy deposited per unit mass ong>ofong> material as a

result ong>ofong> ionization. It is caused by mainly protons. Electrons

are important for some planetary missions. TID may cause

drift in parameters ong>ofong> active electronic parts. TID depends on

orbit altitude, location, and time. To compute TID we need to

know the integrated particle energy spectrum, that is the effect

ong>ofong> particle energy. As TID increases, materials performance

decreases. Long exposure can cause device threshold shifts,

increased leakage and power consumption, timing changes,

and decreased functionality. Energetic particles can be partially

mitigated with shielding. Figure 3 shows the total dose

calculations for LEO satellite RASAT (the Turkish word for

observation), which is the second remote-sensing satellite

after the launch Turkey’s first remote sensing satellite B˙ILSAT

ong>ofong> TÜB˙ITAK UZAY. As it is clearly seen from Fig. 3, electrons

are more effectively shielded than protons. Using radhard

devices and considering a proper shielding, TID effects can

be decreased.

B. Single Event Effect (SEE)

SEE is an instantaneous failure mechanism and expressed

in terms ong>ofong> failure rate. Its are an important issue for all

Fig. 3. Total Dose calculations for LEO satellite RASAT. The relation

between Al shielding thickness and total dose in rads. The total dose and the

contribution ong>ofong> electrons, bremsstrahlung, trapped protons and solar protons

are represented in black, red, green, blue and light-blue, respectively.

spacecraft. SEE results from, as the term suggests, a single,

energetic particle. Some ong>ofong> the early pioneering work was by

May and Woods, who investigated alpha-particle-induced song>ofong>t

errors [1]. In their work the source ong>ofong> alpha particles was not

from space but rather from the natural decay from uranium

and thorium present in integrated circuit packaging materials.

Single event phenomena can be classified into three effects (in

order ong>ofong> permanency):

1) Single event upset (song>ofong>t error): Single event upset (SEU)

is defined as the error caused by a radiation belt or

cosmic ray oriented particle pass through microelectronic

circuits and leaving electron-hole pairs behind.

They are song>ofong>t errors and non-destructive but requires

external interaction. A reset or switch ong>ofong>f results the

normal device performance. SEU can be seen in analog,

digital or optical components, or surrounding interface

circuits. The worse ong>ofong> SEU is single-event functional

interrupt (SEFI) in which the device is set to test mode,

halt or undefined state. SEFI requires a power reset for

recovery.

2) Single event latch up (song>ofong>t or hard error): SEL is

triggered by heavy ions, protons and neutrons. They

are potentially destructive and can be recoverable by

power ong>ofong>f-on reset. If power is not removed quickly,

fatal failure may happen due to excessive heat, metalization

ong>ofong> bond wire failure. SEL is strongly temperature

dependent: the threshold for latch up decreases

at high temperature, and the cross section increases as

well [2,3]. Characterization ong>ofong> latch-up is difficult for

complex circuits but modern devices may have different

latch-up paths.


TABLE I

SUMMARY OF SPACE RADIATION EFFECTS, IMPACTS AND MITIGATION TECHNIQUES.

EFFECT SOURCE IMPACT MITIGATION

TID dominated by protons, and threshold shifts, increased leakage and Shielding

electrons for planetary missions power consumption, timing changes (effective for electron)

DD neutrons, protons, alpha particles, gain degradation and (partly) shielding

heavy ions, and very high energy gamma photons leakage current in bipolar transistors

SEE heavy ions, protons, neutrons change state ong>ofong> memory element, latch-up, Redundancy, power cycling,

voltage spike signal, damage to gate oxide EDAC, latch-up protection circuit

3) Single event burnout (hard failure): Single event burnout

(SEB) is caused by high current state and device fails

permanently. It is triggered by heavy ions, partly by

protons and neutrons. SEBs occur at CMOS, power

BJTs and MOSFETs. The types ong>ofong> SEBs are burnout ong>ofong>

power MOSFETs, gate rupture, frozen bits, and noise in

CCDs. SEB are more likely to happen with increasing

temperature [4]. If a single ionizing particle leads to a

conducting path in a power MOSFET, the event is called

single-event gate rupture (SEGR). The very fist SEGR

is reported by Fischer in 1987 [5].

Fig. 4. Displacement Cascade Damage in Silicon (Credit: NOAA/SEE).

C. Displacement Damage (DD)

DD is caused by neutrons, protons, alpha particles, heavy

ions, and very high energy gamma photons. They change the

arrangement ong>ofong> the atoms in the lattice. Figure 4 shows a

pictorial representation ong>ofong> collision cascade in e.g. Si semiconductor.

These collisions are produced by incident heavy

particles and secondary particles. DD can be created by proton

at all energies, electron with energies >150 keV. Compared to

TID and SEE, DD is less concerned. Only a fraction ong>ofong> 1%

ong>ofong> the energy loss goes into displacement process Dale et al.

1991 [6]. A typical DD effect would be gain degradation and

leakage current in bipolar transistors.

A. Spenvis 1

IV. RADIATION ENVIRONMENT MODELS

Space Environment Information System (Spenvis) ong>ofong> ESA is

an interactive modeling interface for space environment and its

effects. It includes radiation belts, solar particles, cosmic rays,

plasmas, gases. After defining the orbital parameters, one can

calculate particle fluxes, radiation doses for simple geometries,

a sectoring analysis for dose calculations in more complex

geometries, damage equivalent fluences, Geant4 Monte Carlo

simulations, LET, flux and SEE rates. Geomagnetic field lines

are also included, as well as world map visualization ong>ofong> the

satellite data, panel plots ong>ofong> the measured parameters. Micrometeoroid

and space junk models are also implemented.

B. CREME96 2

The Cosmic Ray ong>Effectsong> on Micro-Electronics (1996 Revision)

CREME96, is a group ong>ofong> four subprograms (SPEC,

LET, BENDEL, and UPSET). They are used for creating

numerical models ong>ofong> radiation environment and evaluating the

effect. SPEC is suitable for spectral analysis ong>ofong> integral and

differential energy, while LET (Linear Energy Transfer) produces

integral and differential spectra for different elements.

BENDEL and UPSET is used at the impact evaluation steps.

C. AE/AP Trapped Particles

AE/AP calculates trapped electron and proton fluxes in

Earth’s radiation belt. These are omni-directional, electron (AE

maps) and proton (AP maps) fluxes in 0.04-7 MeV energy

range for electrons and 0.1-400 MeV for protons. The flux

values are stores as energy functions. The very fist version

ong>ofong> series (AE-1 and AP-1) goes back to 1966 by J. I. Vette

1 http://www.spenvis.oma.be/

2 https://creme96.nrl.navy.mil/


[7]. The different updated electron models ong>ofong> AE can be

distinguished as inner or outer zone models and solar cycle

maximum or minimum conditions. AE-8 covers the whole L

range and both solar cycle extrema. The AP maps are different

in energy range and solar cycle phase. AP-8 includes the whole

energy range and both solar cycle extrema.

V. CONCLUSION

The radiation type and effects are depend on location, timing

and duration ong>ofong> the mission. There are possible mitigation

techniques for each harmful effect but no single solution exist

for all impacts. ong>Radiationong> related problems are complex to

model thus require case by case bases mitigations.

REFERENCES

[1] T.C. May, M.H. Woods, ”Alpha-particle-induced song>ofong>t errors in dynamic

memories,” IEEE Trans. on Electron Devices, vol. ED-26, no. 1, pp. 2-9,

Jan. 1979.

[2] I. Mouret, M. Allenspach, R.D. Schrimpf, J.R. Brews, K.F. Galloway, P.

Calvel, ”Temperature and angular dependence ong>ofong> substrate response in

SEGR,” IEEE Trans. on Nuclear Science, vol. 41, no. 6, pp. 2216-2221,

1994.

[3] I. Mouret, M.-C. Calvet, P. Calvel, P. Tastet, M. Allenspach, K.A. LaBel,

J.L. Titus, C.F. Wheatley, R.D. Schrimpf, K.F. Galloway, ”Experimental

evidence ong>ofong> the temperature and angular dependence in SEGR,” Proceedings

ong>ofong> the Third European Conference on ong>Radiationong> and its ong>Effectsong> on

Components and Systems (RADECS), Arcachon, France, Sept. 1995.

[4] G.H. Johnson, R.D. Schrimpf, K.F. Galloway, R. Koga, ”Temperature

dependence ong>ofong> single-event burnout in n-channel power MOSFETs,” IEEE

Trans. on Nuclear Science, vol. 39, pp. 1605-1612, 1992.

[5] T.A. Fischer, ”Heavy-ion-induced, gate-rupture in power MOSFETs,”

IEEE Trans. on Nuclear Science, vol. 34, no. 6, pp. 1786-1791, 1987.

[6] Dale C, Marshall P (1991) Displacement damage in SI imagers for space

applications. Proc. SPIE Charge-Coupled Devices and Solid State Optical

Sensors II, Vol. 1447, p. 70-86,

[7] J. I. Vette, A. B. Lucero, J. A. Wright, J. H. King, J. P. Lavine, W. L.

Imhong>ofong>, C. O. Bostrom, D. S. Beall, J. C. Armstrong, H. H. Heckman, P.

J. Lindstrom, G. H. Nakano, G. A. Paulikas and J. B. Blake, ”Models

ong>ofong> the Trapped ong>Radiationong> Environment”, NASA SP-3024 by NASA,

Washington, D.C., 1966

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