ASTM F1190-93
(Practice)Standard Guide for Neutron Irradiation of Unbiased Electronic Components
Standard Guide for Neutron Irradiation of Unbiased Electronic Components
SCOPE
1.1 This practice applies to the exposure of unbiased silicon (Si) or gallium arsenide (GaAs) semiconductor components to neutron radiation from a nuclear reactor source. Only the conditions of exposure are addressed in this practice. The effects of radiation on the test sample should be determined using appropriate electrical test methods.
1.2 System and subsystem exposures and test methods are not included in this practice.
1.3 This practice is applicable to irradiations conducted with the reactor operating in either the pulsed or steady-state mode. The practical limits for neutron fluence ([phi]eq,1MeV,Si or [phi]eq,1MeV,GaAs) in semiconductor testing range from approximately 10 to 10 16 n/cm .
1.4 This practice addresses those issues and concerns pertaining to irradiations with neutrons of energies greater than 10 keV.
1.5 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: F 1190 – 93
Standard Practice for
Neutron Irradiation of Unbiased Electronic Components
This standard is issued under the fixed designation F 1190; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope Testing of Electronics
E 722 Practice for Characterizing Neutron Energy Fluence
1.1 This practice applies to the exposure of unbiased silicon
Spectra in Terms of an Equivalent Monoenergetic Neutron
(Si) or gallium arsenide (GaAs) semiconductor components to
Fluence for Radiation-Hardness Testing of Electronics
neutron radiation from a nuclear reactor source. Only the
F 867M Guide for Ionizing Radiation Effects Testing of
conditions of exposure are addressed in this practice. The
Semiconductor Devices
effects of radiation on the test sample should be determined
F 980 Guide for the Measurement of Rapid Annealing of
using appropriate electrical test methods.
Neutron-Induced Displacement Damage in Semiconductor
1.2 System and subsystem exposures and test methods are
Devices.
not included in this practice.
2.2 Other Documents:
1.3 This practice is applicable to irradiations conducted with
2.2.1 The Department of Defense publishes every few
the reactor operating in either the pulsed or steady-state mode.
years a compendium of nuclear reactor facilities which may be
The practical limits for neutron fluence (F or
eq, 1 MeV, Si
suitable for neutron irradiation of electronic components:
F ) in semiconductor testing range from approxi-
eq, 1 MeV, GaAs
9 16 2
DASIAC SR-94-009, April 1996, Guide to Nuclear Weap-
mately 10 to 10 n/cm .
ons Effects Simulation Facilities and Techniques
1.4 This practice addresses those issues and concerns per-
2.3 The Office of the Federal Register, National Archives
taining to irradiations with neutrons of energies greater than 10
and Records Administration publishes several documents
keV.
which delineate the regulatory requirements for handling and
1.5 This standard does not purport to address all of the
transporting radioative semiconductor components:
safety concerns, if any, associated with its use. It is the
Code of Federal Regulations: Title 10 (Energy), Part 20,
responsibility of the user of this standard to establish appro-
Standards for Protection Against Radiation
priate safety and health practices and determine the applica-
Code of Federal Regulations: Title 10 (Energy), Part 30,
bility of regulatory limitations prior to use.
Rules of General Applicablity to Domestic Licensing of
2. Referenced Documents
Byproduct Material
Code of Federal Regulations: Title 49 (Transportation),
2.1 ASTM Standards:
Parts 100 to 177
E 170 Terminology Relating to Radiation Measurements
and Dosimetry
3. Terminology
E 264 Test Method for Determining Fast-Neutron Reaction
3.1 1 MeV equivalent fluence—this expression is used by
Rates by Radioactivation of Nickel
the radiation-hardness testing community to refer to the char-
E 265 Test Method for Measuring Reaction Rates and Fast-
2 acterization of an incident neutron energy fluence spectrum,
Neutron Fluences by Radioactivation of Sulfur–32
F(E), in terms of the fluence of monoenergetic neutrons at 1
E 668 Practice for Application of Thermoluminescence
MeV energy required to produce the same displacement
Dosimetry (TLD) Systems for Determining Absorbed Dose
damage in a specified irradiated material as F(E) (see Practice
in Radiation-Hardness Testing of Electronic Devices
E 722 for details).
E 720 Guide for Selection and Use of Neutron-Activation
3.1.1 Discussion—Historically, the material has been as-
Foils for Determining Neutron Spectra Employed in
2 sumed to be silicon (Si). The emergence of gallium arsenide
Radiation-Hardness Testing of Electronics
(GaAs) as a significant alternate semiconductor material,
E 721 Method for Determining Neutron Energy Spectra
whose radiation damage effects mechanisms differ substan-
with Neutron-Activation Foils for Radiation-Hardness
tially from Si based devices, requires that future use of the 1
This practice is under the jurisdiction of ASTM Committee F-1 on Electronics
and is the direct responsibility of Subcommittee F01.11 on Quality and Hardness Annual Book of ASTM Standards, Vol 10.04.
Assurance. Available from Defense Special Weapons Agency, Washington, DC 20305-
Current edition approved Aug. 15, 1993. Published October 1993. Originally 1000.
published as F 1190 – 88. Last previous edition F 1190 – 88. Available from the Superintendent of Documents, U.S. Government Printing
Annual Book of ASTM Standards, Vol 12.02. Office, Washington, DC 20402.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
F 1190
MeV equivalent fluence expression include the explicit speci- 6.1.1 All nuclear reactors produce gamma radiation coinci-
fication of the irradiation semiconductor material. dent with the production of neutrons. If a separation of neutron
3.2 silicon damage equivalent (SDE)—archaic expression (n) and gamma ray (g) degradation is desired, either the n/g
synonymous with “1 MeV equivalent fluence in silicon.” ratio must be increased to the point at which gamma effects are
3.3 equivalent monoenergetic neutron fluence negligible or the test sample degradation must first be charac-
(F )—an equivalent monoenergetic neutron fluence terized in a “pure” gamma ray environment under zero bias
eq,Eref, mat.
that characterizes an incident energy-fluence spectrum, F(E), conditions. The use of such data from a gamma ray exposure to
in terms of the fluence of monoenergetic neutrons at a specific separate neutron and gamma effects obtained in a neutron
energy, Eref, required to produce the same displacement exposure may be a complex task. If this approach is used,
damage in a specified irradiated material, mat. Guide F 867 should be used as a reference.
3.3.1 Discussion—The appropriate expressions for com-
6.1.2 TRIGA-type reactors (Training Research and Isotope
monly used 1 MeV equivalent fluence are F for
eq, 1 MeV, Si production reactor manufactured by General Atomics) deliver
silicon semiconductor devices and F for gallium
gamma dose during neutron irradiations that can vary consid-
eq, 1 MeV, GaAs
arsenide based devices. See Practice E 722 for a much more
erably depending on the immediately preceding operating
thorough treatment of the meaning and significant limitations
history of the reactor. A TRIGA-type reactor that has been
imposed on the use of these expressions.
operating at a high power level for an extended period prior to
the semiconductor component neutron irradiation will contain
4. Summary of Practice
a larger fission product inventory that will contribute signifi-
4.1 Evaluation of neutron radiation-induced damage in
cantly higher gamma dose than a reactor that has had no recent
semiconductor components and circuits requires that the fol-
high level operations.
lowing steps be taken:
6.2 Temperature Effects—Annealing of neutron damage is
4.1.1 Select a suitable reactor facility where the radiation
enhanced at elevated temperatures. Elevated temperatures may
environment and exposure geometry desired are both available
occur during irradiation, transportation, storage, or electrical
and currently characterized. A reasonably complete list is
characterization of the test devices.
contained in DASIAC SR-94-009.
6.3 Dosimetry Errors—Neutron fluence is typically re-
4.1.2 Prepare test plan and fixtures,
ported in terms of an equivalent 1 MeV monoenergetic neutron
4.1.3 Conduct pre-irradiation electrical test of the test
fluence in the specified irradiated material (F or
sample, eq, 1 MeV, Si
F ) in units of neutrons per square centimeter.
4.1.4 Expose test sample and dosimeters, eq, 1 MeV, GaAs
ASTM guidelines and standards exist for calculating this value
4.1.5 Retrieve irradiated test sample,
from measured reactor characteristics. However, reactor facili-
4.1.6 Read dosimeters,
ties may not routinely remeasure the neutron spectrum, (using
4.1.7 Conduct post-irradiation electrical tests, and
Guide E 720 and Method E 721) at the test sample exposure
4.1.8 Repeat 4.1.4 through 4.1.7 until the desired cumula-
sites. A currently valid determination of the neutron spectrum
tive fluence is achieved or until degradation of the test device
provides essential data needed to accurately ascertain the
will not allow any further useful data to be taken.
equivalent 1 MeV monoenergetic neutron fluence in the
4.2 Operations addressed in this practice are only those
specified irradiated material. Lack of this critical data can
relating to reactor facility selection, test procedure and fixture
result in substantial error. Therefore the experimenter must
development, positioning and exposure of the test sample, and
accept responsibility for obtaining a current valid determina-
shipment of the irradiated samples to the parent facility.
tion of the 1 MeV equivalent fluence in silicon or GaAs, as
Dosimetry methods are covered in existing ASTM standards
needed, from the reactor facility operator. This may require a
referenced in Section 2, and many pre- and post-exposure
recharacterization of the reactor test facility, or the particular
electrical measurement procedures are contained in the litera-
test configuration.
ture. Dosimetry is usually supplied by the reactor facility.
6.4 Recoil Ionization Effects—Ionization effects from neu-
5. Significance and Use
tron recoils within a semiconductor device may be significant
5.1 Semiconductor devices are permanently damaged by
for some device types at very high neutron fluences, although
fast neutrons (E > 10 keV). The effect of such damage on the
under normal conditions, ionization due to the gamma radia-
performance of an electronic component can be determined by
tion from the source will be much greater than the ionization
measuring the component electrical characteristics before and
from recoils.
after exposure to fast neutrons in the neutron fluence range of
6.5 Test Configuration Effects—Extraneous materials in the
interest. The resulting data can be utilized in the design of
vicinity of the test specimens can modify the environment at
electronic circuits which are tolerant of the degradation exhib-
the test sample location. Both the neutron spectrum and the
ited by that component.
gamma field can be altered by the introduction of such material
5.2 This practice provides a method by which the exposure
even if these materials are not interposed between the reactor
of semiconductor devices to neutron irradiation may be per-
core and the test devices.
formed in a manner which is repeatable and which will allow
6.6 Thermal Neutron Effects—Thermal neutrons (;0.04
comparison to be made of data taken at different facilities.
eV) interact with the materials of the devices being irradiated
6. Interferences
causing them to become radioactive. As this means that
6.1 Gamma Effects: irradiated parts cannot be handled or measured in reasonable
F 1190
times following exposure, it is common practice to shield test product inventory increases as the total exposure time in-
parts from the thermal neutrons. Borated polyethylene or creases.
cadmium shields are commonly used. Cadmium capture of
7.1.3 Dosimetry and Field Mapping. Mechanical supports
thermal neutrons produces more gamma rays than boron
or reactor control elements may cause localized perturbation of
capture, thus producing a lower h/g ratio when such a shield is
the neutron flux; therefore, mapping of the area in which
used. When possible, borated polyethylene shields are pre-
samples are to be exposed is required to verify uniformity. Use
ferred. Fast Burst Reactor (FBR) neutron spectra have a small
sulfur or nickel dosimetry for mapping in accordance with Test
thermal neutron component, whereas TRIGA reactors inher-
Method E 264 or E 265. Report the resulting neutron fluence in
ently produce a very large thermal neutron flux. While most
terms of the 1 MeV equivalent neutron fluence in the specified
facilities providing neutron irradiation for semiconductor parts
irradiated material (F or F ) in accor-
eq, 1 MeV, Si eq, 1 MeV, GaAs
will automatically provide the thermal neutron shields, it is the
dance with Practice E 722.
experimenter’s responsibility to verify that such a shield is
7.1.4 Concurrent with the neutron mapping, determine the
employed during the test.
gamma total dose at the exposure location using Thermolumi-
nescent Dosimeter (TLD) dosimetry in accordance with Prac-
7. Procedure
tice E 668. Because the neutron energy spectrum extends to
7.1 Reactor Facility Selection:
thermal energy levels and because Li has a large absorption
7.1.1 Reactor Operating Modes and Fluence Levels—Two
cross section for thermal neutrons, the use of CaF rather than
types of reactors are generally used for evaluating the effects of
LiF TLDs is recommended to avoid a potential error in the
fast neutrons (E > 10 keV) on electronic components. These
gamma dose measurement. CaF is also a better match for
reactors, the FBR and the TRIGA type reactor, can be operated
energy absorption of semiconductor materials. Keep in mind
in either a pulsed or a steady-state mode. The minimum pulse
the warning in 6.1.2.
width for the FBR is approximately 50 μs and the TRIGA type
7.2 Test Plan and Fixtures:
has a nominal pulse width of 10 ms. The pulse widths of both
7.2.1 All reactor facilities require a test procedure or test
types of reactors increase as the peak power is decreased.
plan. The procedure should specify the location of the test
Therefore, if minimum pulse widths are desired, the adjustment
sample relative to the reactor core and the desired reactor burst
of fluence is best accomplished by adjusting the distance
temperature or equivalent parameter used by the test facility to
between the core and the sample, rather than adjusting the peak
scale the reactor operation in the burst mode. The test facility
power level. In the single-pulse mode, the FBR typically has a
13 2 may require only the target fluence, from which the location of
maximum fluence (F )upto8 3 10 n/cm outside
eq, 1 MeV, Si
14 2 the sample and burst temperature will be determined by facility
the core and 6 3 10 n/cm inside the core. TRIGA-type
operating personnel. In the steady-state mode, the power level
reactors have a maximum single pulse fluence that varies with
and duration of exposure is required. This too can be provided
the reactor and the exposure position within the core, but
13 15 2 by facility operators if des
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.