Single-Event Upsets and Microelectronics (Why neutrons ... · Sources of soft fails: – -particles from the natural radiation in chip packaging (ceramic, silicide, insulators, wafers,

Single-Event Upsets and Microelectronics

(Why neutrons matter to the electronics industry)Michael Gordon, Ken Rodbell

IBM TJ Watson Research CenterYorktown Heights, NY 10598

Neutron Monitor Community Workshop, October 24, 2015 © 2006 IBM Corporation

Introduction

Single Event Upsets

The neutron radiation environment

Some neutron-induced SEU results on commercial SRAM

Summary

Questions and answers

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Single Event Upsets What is a soft fail?

– Errors in chips (logic, memory) that don’t cause permanent damage

– Created by passage of energetic ionizing radiation through the sensitive volume of chips

– This is a reliability problem for servers, laptops, smart devices, pacemakers, airplanes, autonomous cars, drones…

Sources of soft fails:– -particles from the natural radiation in chip packaging (ceramic, silicide, insulators,

wafers, copper)

– High energy neutrons which create highly ionizing particles when they interact w/ silicon (spallation)

– Thermal neutrons interacting with 10B through the 10B(n,) reaction

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Single Event Upsets in the News (Sun Microsystems)

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Single Event Upsets in the News (defibrillators)

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Single Event Upsets in the News (Pluto mission)

Just after the Jupiter flyby, New Horizons suffered its first computer glitch. For spacecraft outside Earth’s protective atmosphere, high-energy cosmic rays occasionally zip through computer memory, causing a crash and restart. Calculations indicated that there would be one such crash during the nine-and-a-half-year trip to Pluto. Instead, they occurred almost once a year. But none caused lasting damage, and they proved good learning experiences.

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IBM J. Res. Devel. Vol 52. No 3, 2008 IBM J. Res. Devel. Vol 40. No 1, 1996

Two complete issues of IBM J. Res. Dev. devoted to SEU research

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Alpha particles– Sources: Solder bump (C4’s), underfill,

metals other packaging materials

– The -particle energy and flux are attenuated by passing through other materials

– Measurable effects on SEU for -particle emissivities of <2/khr-cm2

(1.5 /hr on a 300 mm dia. wafer)

– Can reduce the influence of -particles on SEU by reducing flux (shielding, screening)

– But their range is small, < 100 m, fortunately!

Radiation environment: -particles near chips

E. Cannon, ICICDT, 2007

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Charge Deposited and Range of particles in Si

Alpha particles

deposit lots of charge

but are very short ranged

Cause SEU through direct ionization

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Energy (MeV)

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Cosmic Rays and their effect on Single Event Upsets

Cosmic rays– Cosmic rays (mostly protons) interact with atoms in the atmosphere– Neutrons observed on the ground come from interactions of energetic protons and

14N or 16O in the atmosphere– Energy range- meV (thermal) to GeV– Velocity of neutrons: 150 MeV neutrons travel at ~c/2

Ionizing radiation in chips– Terrestrial neutrons striking chips interact with silicon atoms or metals near the

transistors– “Spallation” occurs through 28Si(n,X) reaction and generates recoil ions– These recoil ions generate charge and can cause SEU– High energy protons (E>50 MeV) cause same effect as neutrons on chips

• So some labs use external beam of protons as proxy for neutrons• More availability of proton beams (proton therapy centers)• Significantly higher flux for protons compared to neutrons from spallation sources

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Terrestrial Neutrons and effect on semiconductors Two types of neutron-induced SEU experiments

– Accelerated testing using external beam of neutrons• Individual chips, or system tested• Use the acceleration factor, ~ 1E6 • Flux from source integrated over energy > 10 MeV / terrestrial (NYC) flux

– “Life” (or real-time) testing using natural flux of neutrons at high elevation• Assess SEU in “real-world” conditions• Acceleration factor, ~ 10-15• Use calculated neutron flux (or measured if available)• See influence of neutrons and alpha particle• Systems tested rather than individual chips• Tests often take months to get adequate statistics

Life-testing can be run underground to get a measure of the alpha flux from the packaging (effect can be subtracted from the altitude meas.)

Testing usually follows prescription of JESD89a– Data taken by IBM and Paul Goldhagen, using Paul’s Bonner sphere system, and

resulting model are “gold standard” for the semiconductor industry

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Terrestrial Neutron Measurements

Figure E.2.1 — The differential flux of cosmic-ray-induced neutrons as a function ofneutron energy under reference conditions (sea level, New York City, mid-level solaractivity, outdoors). The data points are the reference spectrum, the solid curve is theanalytic fit to the reference spectrum, and the dashed curve is the model from theprevious version of this standard, JESD89 (2001).

M. Gordon, et. al, IEEE Trans. Nucl. Sci. 51(6), 3427, Dec 2004

data

analyticmodelfrom Goldhagen

Model from originalJESD89 spec.

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Why are cosmic ray neutrons important?

High-energy neutrons striking silicon nuclei can cause spallation reactions, releasing light and heavy ions.

The ions have high LET (linear energy transfer) and which can initiate SEU

The following table shows the threshold energy needed for the reactions to occur-– higher energy neutrons- more exit

channels

F. Wrobel, et. al., IEEE Trans. Nucl. Sci. Vol 47, No. 6, pp. 2580, Dec. 2000

25Mg + 2.75 MeV

28Al + p 4.00 MeV

27Al + d 9.70 MeV

24Mg + n, 10.34 MeV

27Al + n,p 12.00 MeV

26Mg +3He 12.58 MeV

21Ne + 2 12.99 MeV

27Mg + 2p 13.90 MeV

24Na + p, 15.25 MeV

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Normalized high energy neutron flux sources

C. Slayman, IEEE Trans, Nucl. Sci., Vol. 57, No. 6, 3163, Dec. 2010.

Flux @ 40,000’

180 MeV P + W

800 MeV P+ W

500 Mev P + Pb/Fe

800 MeV P + W (mod)

392 MeV P + Pb

Normalized to JEDEC from 1 MeV-1 GeV

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Secondary ion production for n(si,x) atmospheric and monoenegetic neutrons

S. Serre, et al., IEEE Trans, Nucl. Sci., Vol. 59, No. 4, 714, Aug. 2012.

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Thermal Neutrons, a Problem?

The magnitude/shape of the thermal neutron spectrum depends on the scattering of neutrons from the environment (roof, walls, building materials)

10B and other isotopes have large capture cross sections (highprobability of capture). 20% of B is 10B.

n + 10B 7Li + (1.5 MeV); Cross section 3840 B

3He(n,p)

10B(n,)6Li(n,)

104

103

10-2 100 From KnollNeutron energy (eV)

Thermal neutrons will cause SEU’sif there is an appreciable amount of 10B immediately surroundingtransistors

Solution is to eliminate B or enrich to 11B

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Neutron Monitor Community Workshop, October 24, 2015 © 2006 IBM Corporation17

Failure rate caused by neutrons and alpha particles

J.L. Autran, et al., Radiation Effects Data Workshop (REDW), RADECS, IEEE, 2014, 1

Commercial 130 nm, 65 nm and 40 nm SRAM devices

2.3 /khr-cm2

0.92 /khr-cm2FIT= error in 109 hours

ASTEP is in the French Alps, with an active neutron monitor

-particle emissivity


ASTEP (French Alps), 2552 m, AF=6 & underground test facility

J. L. Autran, et al., Radiation Effects Data Workshop, IEEE, 2014, pp. 1-8.

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Real-time, modeling and accelerated neutron testing

Good correlationbetween modeling,real time and accelerated testing

J. L. Autran, et al., Radiation Effects Data Workshop, IEEE, 2014, pp. 1-8.

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ASTEP neutron monitor

J.L. Autran, et al., IRPS, 2012, 3C.5.1 - 3C.5.9

counts/hr

atmospheric pressure

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Leadville neutron monitor in new home, 2009

Leadville, CO (10,200’)388 kcounts / hr per tube

Durham, NH (~50’)42.1 kcounts / hr per tube

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Effect of solar activity on SER (need for real-time neutron monitor)

Rodbell, IEEE NSREC short course, 2013

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Summary

Single event upsets are a major reliability issue in the electronics industry

Scaling device size (Moore’s law) helps, but the critical charge required to flip bits is shrinking as well

Real-time and neutron (or proton) accelerated testing is required to assess the device or system SER

Having a real-time neutron monitor at or near the real-time test site makes the determination of the acceleration factor more precise, compared to estimating the neutron flux from a calculator

We at IBM support funding to keep US neutron monitors operational

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Documents

Single-Event Upsets and Microelectronics (Why neutrons ... · Sources of soft fails: – -particles from the natural radiation in chip packaging (ceramic, silicide, insulators, wafers,