IEC 62396-2:2012

IEC 62396-2


®


Edition 1.0 2012-09



INTERNATIONAL



STANDARD




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inside


Process management for avionics – Atmospheric radiation effects –
Part 2: Guidelines for single event effects testing for avionics systems

IEC 62396-2:2012(E)

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IEC 62396-2



®



Edition 1.0 2012-09







INTERNATIONAL





STANDARD











colour

inside










Process management for avionics – Atmospheric radiation effects –

Part 2: Guidelines for single event effects testing for avionics systems




























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ELECTROTECHNICAL

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CONTENTS

FOREWORD . 4


INTRODUCTION . 6

1 Scope . 7

2 Normative references . 7


3 Terms and definitions . 7

4 Abbreviations used in the document . 7

5 Obtaining SEE data . 9

5.1 Types of SEE data . 9
5.2 Use of existing SEE data . 9
5.2.1 General . 9
5.2.2 Heavy ion data . 9
5.2.3 Neutron and proton data . 10
5.2.4 Thermal neutron data . 10
5.3 Deciding to perform dedicated SEE tests . 10
6 Availability of existing SEE data for avionics applications . 11
6.1 Variability of SEE data. 11
6.2 Types of existing SEE data that may be used . 11
6.2.1 General . 11
6.2.2 Sources of data, proprietary versus published data. 12
6.2.3 Data based on the use of different sources . 13
6.2.4 Ground level versus avionics applications. 19
6.3 Sources of existing data . 20
7 Considerations for SEE testing . 21
7.1 General . 21
7.2 Selection of hardware to be tested . 22
7.3 Selection of test method . 22
7.4 Selection of facility providing energetic particles . 23
7.4.1 Radiation sources . 23
7.4.2 Spallation neutron source . 23
7.4.3 Monoenergetic and quasi-monoenergetic beam sources . 24
7.4.4 Thermal neutron sources . 25
7.4.5 Whole system and equipment testing . 25

8 Converting test results to avionics SEE rates . 26
8.1 General . 26
8.2 Use of spallation neutron source . 27
8.3 Use of SEU cross-section curve over energy . 27
8.4 Measured SEU rates for different accelerator based neutron sources . 30
8.5 Influence of upper neutron energy on the accuracy of calculated SEE rates;
verification and compensation . 30
Annex A (informative) Sources of SEE data published before 2000 . 32
Bibliography . 33

Figure 1 – Comparison of Los Alamos, TRIUMF and ANITA neutron spectra with
terrestrial / avionics neutron spectra (JESD-89A and IEC 62396-1) . 15
Figure 2 – Variation of high energy neutron SEU cross-section per bit as a function of
device feature size for SRAM and SRAM arrays in FPGA and microprocessors . 17

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62396-2 © IEC:2012(E) – 3 –


Figure 3 – Percentage fraction of SEU rate from atmospheric neutrons contributed by

neutrons with E < 10 MeV . 18

Figure 4 – Comparison of mono-energetic SEU cross-sections with Weibull and piece-

wise linear fits . 29




Table 1 – Sources of existing data (published after 2000) . 20

Table 2 – Spectral distribution of neutron energies . 30

Table A.1 – Sources of existing SEE data published before 2000 . 32

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INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________



PROCESS MANAGEMENT FOR AVIONICS –

ATMOSPHERIC RADIATION EFFECTS –



Part 2: Guidelines for single event effects

testing for avionics systems





FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62396-2 has been prepared by IEC technical committee 107:
Process management for avionics.
This standard cancels and replaces IEC/TS 62396-2 published in 2008. This first edition
constitutes a technical revision.
This first edition includes the following significant technical changes with respect to the
technical specification IEC/TS 62396-2.
a) Clause 5 information expanded including additional information in sections on heavy ion
data, neutron and proton data and thermal neutron data.
b) The neutron sources Clause 6 has been updated, Figure 1 now contains data on
additional radiation simulators, and Figure 2 contains more recent data with results for
feature sizes below 100 nm. A new Figure 3 contains data on low energy neutron
(< 10 MeV) SEU percentage fraction.

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62396-2 © IEC:2012(E) – 5 –


c) The sources of existing data (radiation SEE data) table has been split in to two tables: one

for post 2000 sources and the other for pre 2000 sources which is now in Annex A.

d) The Anita spallation neutron source has been added to Clause 7.


e) A new subclause, 7.4.5, has been added on whole system and equipment testing.

f) A new subclause, 8.4, provides a comparison between accelerator based neutron sources.

g) A new subclause, 8.5, compares the influence of upper neutron energy for neutron

sources.


The text of this standard is based on the following documents:


FDIS Report on voting
107/186/FDIS 107/192/RVD

Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 62396 series, published under the general title Process
management for avionics – Atmospheric radiation effects, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

A bilingual edition of this document may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.

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INTRODUCTION


This industry-wide international standard provides additional guidance to avionics systems

designers, electronic equipment component manufacturers and their customers to determine

the susceptibility of microelectronic devices to single event effects. It expands on the

information and guidance provided in IEC 62396-1.


Guidance is provided on the use of existing single event effects (SEE) data, sources of data

and the types of accelerated radiation sources used. Where SEE data is not available

considerations for testing are introduced including suitable radiation sources for providing

avionics SEE data. The conversion of data obtained from differing radiation sources into

avionics SEE rates is detailed.

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62396-2 © IEC:2012(E) – 7 –


PROCESS MANAGEMENT FOR AVIONICS –

ATMOSPHERIC RADIATION EFFECTS –



Part 2: Guidelines for single event effects

testing for avionics systems








1 Scope

This part of IEC 62396 aims to provide guidance related to the testing of microelectronic
devices for purposes of measuring their susceptibility to single event effects (SEE) induced by
atmospheric neutrons. Since the testing can be performed in a number of different ways,
using different kinds of radiation sources, it also shows how the test data can be used to
estimate the SEE rate of devices and boards due to atmospheric neutrons at aircraft altitudes.
Although developed for the avionics industry, this process may be applied by other industrial
sectors.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 62396-1:2012, Process management for avionics – Atmospheric radiation effects – Part 1:
Accommodation of atmospheric radiation effects via single event effects within avionics
electronic equipment
IEC/TS 62396-3, Process management for avionics – Atmospheric radiation effects – Part 3:
Optimising system design to accommodate the single event effects (SEE) of atmospheric

radiation
IEC/TS 62396-4, Process management for avionics – Atmospheric radiation effects – Part 4:
Guidelines for designing with high voltage aircraft electronics and potential single event
effects
IEC/TS 62396-5, Process management for avionics – Atmospheric radiation effects – Part 5:

Guidelines for assessing thermal neutron fluxes and effects in avionics systems
3 Terms and definitions
For the purpose of this document, the terms and definitions given in IEC 62396-1 apply.
4 Abbreviations used in the document
ANITA Atmospheric-like Neutrons from thIck TArget (TSL, Sweden)
BL1A, BL1B, BL2C Beam line designations at the TRIUMF facility (Canada)
BPSG Borophosphosilicate glass
CMOS Complementary metal oxide semiconductor
COTS Commercial off-the-shelf
D-D Deuterium-deuterium

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DRAM Dynamic random access memory

D-T Deuterium-tritium

DUT Device under test

E Energy

EEPROM Electrically erasable programmable read only memory

EPROM Electrically programmable read only memory

ESA European Space Agency

eV Electron volt

9
FIT Failures in time (failures in 10 hours)

FPGA Field programmable gate array
GeV Giga electron volt
GNEIS Gatchina Neutron Spectrometer (Russia)
GSFC Goddard Space Flight Center
GV Giga volt (rigidity unit)
IBM International Business Machines
IC Integrated circuit
ICE Irradiation of Chips and Electronics
IEEE Trans. Nucl. Sci. IEEE Transactions on Nuclear Science
IUCF Indiana University Cyclotron Facility (USA)
JEDEC JEDEC Solid State Technology Association
JESD JEDEC standard
JPL Jet Propulsion Laboratory
LANSCE Los Alamos Neutron Science Center (USA)
LET Linear energy transfer
LETth Linear energy transfer threshold
MBU Multiple bit upset (in the same word)
MCU Multiple Cell Upset
MeV Mega electron volt
NASA National Aeronautical and Space Agency
PIF Proton Irradiation Facility (TRIUMF, Canada)
PNPI Petersburg Nuclear Physics Institute (Russia)
PSG Phosphosilicate glass
QMN Quasi-monoenergetic neutrons
RADECS Radiations, effets sur les composants et systèmes.
RAM Random access memory

RCNP Research Center of Nuclear Physics (Osaka, Japan)
RVC Result of voting (IEC)
SBU Single Bit Upset
SDRAM Synchronous dynamic random access memory
SEB Single event burn-out
SEE Single event effect
SEFI Single event functional interrupt
SEGR Single event gate rupture
SEL Single event latchup
SEP Solar energetic particles
SER Soft error rate
SET Single event transient
SEU Single event upset
SHE Single event induced hard error

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SRAM Static random access memory

SW Software

TID Total ionizing dose

TNF TRIUMF neutron facility (TRIUMF, Canada)

TRIUMF Tri-University Meson Facility (Canada)

TSL Theodor Svedberg Laboratory (Sweden)

WNR Weapons Nuclear Research (Los Alamos USA)


5 Obtaining SEE data


5.1 Types of SEE data
The type of SEE data available can be viewed from many different perspectives. As indicated,
the SEE testing can be performed using a variety of radiation sources, all of which can induce
single event effects in ICs. In addition, many tests are performed on individual devices, but
some tests expose an entire single board computer to radiation fields that can induce SEE.
However, a key discriminator is deciding on whether existing SEE data that may be used is
available, or whether there really is no existing data and therefore a SEE test on the device or
board of interest has to be carried out.
5.2 Use of existing SEE data
5.2.1 General
The simplest solution is to find previous SEE data on a specific IC device. Data may be
available on SEE caused by heavy ions, protons, high-energy neutrons, or thermal neutrons.
Heavy-ion data is normally only applicable to space applications, where direct ionization by
the primary cosmic ray flux is of concern. However, heavy ion data can be useful for
screening purposes, as described in 5.2.2. Proton data is usually also gathered for space
applications, where primary cosmic rays and trapped particles are of concern. However, high-
energy protons provide a good proxy for neutrons in SEE measurements, as they undergo
very similar nuclear interactions with device materials. Therefore, both existing neutron data
and existing proton data may be applicable to the evaluation of SEE rates in a device of
interest, as described in section 5.2.3. Low-energy (“thermal”) neutrons can also cause SEE
in some devices but such data is only available on a very small number of devices (see
section 5.2.4) and it involves neutron interactions with boron-10 rather than silicon.
5.2.2 Heavy ion data
An important resource that can be utilized to eliminate devices is the results from heavy ion
SEE testing carried out to support space programs (~80 % of the devices tested for space
applications are tested only with heavy ions). This heavy ion SEE data can be used to

calculate SEE data from high energy neutrons and protons by utilizing a number of different
calculation methods, but this requires the active involvement of a radiation effects expert in
the process. Heavy ion testing is characterized by the LET (linear energy transfer) of the ions
to which the ICs are exposed. The LET is the energy that can be deposited per unit path
2
length, divided by the density (units of MeV⋅cm /mg). With neutron SEE, secondary particles
or recoils created by the neutron interactions act as heavy ions, and the highest possible LET
2
1
of neutron-induced recoils in silicon is ~15 MeV⋅cm /mg [1, 2] . Thus, any device tested with
2
heavy ions that has a LET threshold > 15 MeV⋅cm /mg will be immune from neutron-induced
SEE. In a recent paper summarizing SEE testing at NASA-GSFC [3], 21 ICs of various types
were tested with only heavy ions and eight of them (~40 %) had LET thresholds
2
> 15 MeV⋅cm /mg for diverse SEE effects.
However, for the rare commercial SRAMs that are susceptible to SEL from heavy ions [4], this
susceptibility can be increased due to the presence of small amounts of high Z materials
___________
1
 Numbers in square brackets refer to the Bibliography.

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within the IC, e.g., tungsten plugs, because higher Z recoils are created which can cause SEE

reactions due to their higher values of LET. The high Z materials also lead to higher proton

and neutron SEL cross-sections due to the neutron/proton reactions producing these recoils

with higher LET and energy. Therefore heavy ion SEL cross-sections need to be examined

carefully for applicability to proton-neutron SEL susceptibility caused by embedded high Z

materials in the SRAMs. A suggested conservative value of LET threshold above which a
2

device can be considered immune from SEL induced by neutrons is 40 MeV⋅cm /mg [4].
However, this caution does not apply to the primary rationale given above for eliminating
some devices from consideration for neutron SEE sensitivity based on heavy ion SEE testing,
since only some devices incorporate these higher Z materials and the limitation applies to

SEL.


Heavy ion SEE data should not be used for application to the atmospheric neutron
environment for calculation of neutron cross-section, except by scientists and engineers who
have extensive experience in using this kind of data. Unless otherwise stated explicitly, when
SEE data is discussed in the remainder of this international standard, it refers only to single
event testing using a neutron or proton source, not to the results from testing with heavy ions.
5.2.3 Neutron and proton data
If SEE data on a device of interest is found from SEE tests using high energy neutrons or
protons, it will still require expertise regarding how the data is to be utilized in order to
calculate a SEE rate at aircraft altitudes. Data obtained by IC vendors for their standard
application to ground level systems are often expressed in totally different units, FIT units,
9
where one FIT is one error in 10 device hours, which is taken to apply at ground level.
IC devices are constantly changing. In some cases, devices which had been tested, become
obsolete and are replaced by new devices which have not been tested. The fact that a device
is made by the same IC vendor and is of the same type as the one it replaced does not mean
that the SEE data measured in the first device applies directly to the newer device. In some
cases, small changes in the IC design or manufacturing process can have a large effect in
altering the SEE response, but in other cases, the effect on the SEE response may be
minimal.
5.2.4 Thermal neutron data
There is little data on thermal neutron cross-section. However a number of the spallation
neutron sources including TRIUMF, TSL and ISIS contain a substantial percentage of thermal
neutrons within the high energy beam. Using thermal neutron filters or time of flight it is
possible at such sources to determine thermal neutron cross-section. In addition there are a
number of dedicated thermal neutron sources and these are listed in IEC 62396-1:2012.
A continuing problem with the existing SEE data is that there is no single database that

contains all of the neutron or proton SEE data. Instead, portions of this kind of SEE data can
be found published in many diverse sources. The SEE data in the larger databases is mainly
on much older devices, dating from the 1990s and even 1980s, and is primarily from heavy
ion tests that were performed for space applications and not from testing with protons and
neutrons.
5.3 Deciding to perform dedicated SEE tests
If existing SEE data is not available, for any one of the many reasons discussed above and
which will be further expanded upon below, then there is no real alternative but to carry out
one’s own SEE testing. The advantage of such a test is that it pertains to the specific device
or board that is of interest, but the disadvantage is that it entails making a number of
important decisions on how the testing is to be carried out. These pertain to selecting the
most useful test article (single chip or entire board), nature of the test (static or dynamic
(mainly applicable to board testing), assembling a test team, choosing the facility that
provides the best source of neutrons or protons for testing, scheduling and performing the test,
coping with uncertainties that appear during the test and, finally, using the test results to

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calculate the desired SEE rate for avionics. Many of these issues will be discussed in the

following clauses.



6 Availability of existing SEE data for avionics applications


6.1 Variability of SEE data

Because of the diverse ways that SEE testing is carried out, and the multitude of venues for

how and where such data is published, the availability of SEE data for avionics applications is

not a simple matter.


6.2 Types of existing SEE data that may be used
6.2.1 General
SEE data can be derived from a number of different kinds of tests, and all of the differences
between these tests need to be understood in order to make comparisons meaningful.
Although there are many different types of single event effects, for the purposes of this
international standard, the focus is on three of them: single event upset (SEU), single event
functional interrupt (SEFI) and single event latchup (SEL). SEU pertains to the energy
deposited by an energetic particle leading to a single bit being flipped in its logic state. The
main types of devices that are susceptible to SEU are random access memories (RAMs, both
SRAMs and DRAMs), field programmable gate arrays (FPGAs, especially t
...