9.4.1
Prediction of radiation
damage parameters 
9.4.1.1 General
a. When predicting component SEE rates, the following shall be assessed:
1. The probability of SEE occurrence for the environments as specified in clause 9.2, using the methods specified in clause 9.4.1.2 to 9.4.1.8.
NOTE 1 More information on this method is available in ECSS-E-HB-10-12 Section 8.2.
NOTE 2 Total ionising dose induced in semiconductors can increase sensitivity to single event effects. Therefore, potential SEE/TID synergy can be important in special cases, both in estimating single event rate for the operating environment, as well as assessing the suitability of data collected from proton and ion beam irradiations.
NOTE 3 In some special cases, single event effect rates have been shown to vary significantly depending upon the angle of incidence of the incident particle, even for protons and neutrons.
2. The influence of shielding in attenuating the primary particle environment and modification to its spectrum, as specified in Clause 6.
NOTE The effects of the component packaging (as described in Clause 6.3) can be considered.
9.4.1.2 Heavy ion-induced SEU, MCU (including SMU), and SEFI
a. The probability of single event transients, upsets, functional interrupts and multiple-cell upsets due to ions heavier than protons shall be determined as follows:
1.
If the variation of the ion
cross-section with LET
is known, by using the Integrated RPP (IRPP) approach
described in requirements 9.5.2a.1 and 9.5.2a.3.
2. Otherwise, using either of the following RPP methods:
(a)
The incident particle
differential LET spectrum, integrated over the integral chord-length
distribution in the sensitive volume for which the energy deposition is above
that corresponding to the experimentally-determined LET threshold of the
device, and using the formulation of “
(b)
The differential chord-length
distribution integrated over the incident particle integral LET spectrum, for
which the LET corresponds to energy deposition above the
experimentally-determined threshold of the device, and using the formulation
of: “
b. SEFI analysis shall
1. assess the range of internal operating modes employed in complex digital devices used by the intended application, and
2. use only test data which cover these modes.
9.4.1.3 Proton- and neutron-induced SEU, MCU (including SMU), and SEFI
a. The probability of single event transients, upsets, functional interrupts and multiple-cell upsets due to protons or neutrons shall be determined as follows:
1. If the variation of the cross-section with particle energy is known,
(a) Calculate the probability by integration of the incident differential proton or neutron spectrum over the experimentally determined cross-section of the device as specified in clause 9.5.3.
(b) If experimental data from ion beam irradiations demonstrate that the threshold for SEU, MCU or SEFI for ions is less than 15 MeV×cm2/mg, agree with the customer if the device can be considered immune to proton and neutron SEE effects.
NOTE
The immunity to proton/neutron
SEE for devices with an LET threshold for ion SEE >15 MeV cm2/mg
is an approximation. This assumption becomes inaccurate with the increasing
inclusion of high-Z materials that give rise to nuclear reactions. The
radiation hardness assurance programme resulting from application of
ECSS-Q-ST-60 specifies the approach to be taken in special cases.
2. Otherwise, perform the following:
(a) determine the SEE rate from calculation of the energy-deposition spectrum from proton-nuclear or neutron-nuclear interactions within the representation of the sensitive volume, and
(b) integrate this spectrum with cross-section data from ion-beam irradiations as specified in clause 9.5.3, and
(c) analyse potential problems arising from use of the device, along with appropriate margins.
NOTE The reason is that this method is not as accurate as direct calculation based on proton data.
b. SEFI analysis shall
1. assess the range of internal operating modes employed in complex digital devices used by the intended application, and
2. use only test data which cover these modes.
9.4.1.4 Heavy ion-induced SEL and SESB
b.
Where experimental data
indicate that the normal incidence LET threshold for susceptibility to single
event latch-up or single event
snapback for ions is ³60 MeV×cm2/mg,
it shall be assumed that the
device has negligible probability of SEL or SESB respectively to heavy ions,
when subjected to the electrical and temperature conditions under which the
device is operated in the test and intended application, as specified in clause 9.4.2.
c. For devices with lower thresholds than those specified in requirement 9.4.1.4a, one of the following two methods shall be used:
1.
Determine the probabilities for
SEL and SESB due to heavy ions from the integration of the incident
differential ion LET spectrum over the experimentally-determined cross-section
of the device, as specified in clause 9.5.2.
2. worst case analysis based on experimental data.
NOTE Alternative testing methods (laser or proton irradiation), combined with a cross-section equivalent to the device surface can be used with worst case analysis.
d. If a worst-case analysis is performed in accordance with requirement 9.4.1.4c.2, and the probability is unacceptable to the customer, the cross-section shall be determined experimentally.
9.4.1.5 Proton- and neutron-induced SEL and SESB
b.
Where experimental data
indicate that the LET threshold for susceptibility to single event latch-up or
single event snapback for ions is ³15 MeV×cm2/mg,
or proton or neutron data indicate that the energy threshold for proton/neutron
SEE is ³150 MeV,
it shall be assumed that the
device has negligible probability of SEL or SESB respectively for protons and
neutrons. When subjected to the electrical and temperature conditions under
which the device is operated in the test and intended application, as specified
in clause 9.4.2.
NOTE
1 It is an assumption that devices with an
LET threshold for ions >15 MeV cm2/mg are immune to SEL and SESB.
This assumption becomes inaccurate with the increasing inclusion of high-Z
materials that give rise to nuclear reactions. The radiation hardness assurance
programme resulting from application of ECSS-Q-ST-60 specifies the approach to
be taken in special cases.
NOTE 2 SEL cross sections can increase by a factor of four between 100 and 200 MeV and by a further factor of 1,5 to 500 MeV.
c. For devices with lower thresholds that the ones specified in requirement 9.4.1.5a, the probabilities for SEL and SESB due to protons or neutrons shall be determined by one of the following methods:
1. by integration of the incident differential proton or neutron spectrum over the experimentally determined cross-section of the device, as specified in clause 9.5.3.
2. by worst case analysis.
NOTE Alternative testing methods (laser irradiation), combined with a cross-section equivalent to the device surface can be used with worst case analyses.
9.4.1.6 Heavy ion-, proton- and neutron-induced SEGR, SEDR and SEB
a. For single event gate/dielectric rupture and single event burnout, experimental data shall be used to determine the electrical operational conditions of the device under which neither SEGR nor SEB occurs
NOTE ECSS-E-HB-10-12 Section 8.5.8 describes derating and mitigation techniques for defining electrical operational conditions.
b. Where experimental data show that the threshold for single event gate/dielectric rupture or single event burnout in a device for ions is ³60 MeV×cm2/mg, it shall be assumed that the device has negligible probability of SEGR, SEDR or SEB respectively for operation in heavy-ion, proton and neutron fields, when it is subjected to the electrical and temperature conditions under which the device is operated in the test and intended application in accordance with clause 9.4.2.
c. Where experimental data show that the threshold for SEGR, SEDR or SEB for ions is ³15 MeV×cm2/mg, or proton or neutron data indicate that the energy threshold for proton/neutron SEGR, SEDR or SEB is ³ 150 MeV, it shall be assumed that the device has negligible probability of SEGR, SEDR or SEB respectively when operated in either a proton or neutron field when it is subjected to the operating conditions or the test and application.
d. In the case specified in requirement 9.4.1.6c, the device’s susceptibility to heavy-ion induced SEGR, SEDR and SEB shall be analysed.
9.4.1.7 Heavy ion-, proton- and neutron-induced SET and SED
1. Test the equipment performance under different filter conditions for SET and SED effects by propagating a perturbation signal in the final electrical design of the hardware itself to study its influence at the system level.
NOTE This approach is used when there is sufficient access to inject test pulses to the range of circuit nodes, or using a circuit simulation mode.
2. Use a circuit simulation model, and verify the accuracy of the different components in the circuit model for propagating large amplitude signals, up to the maximum amplitude expected from the SET/SED.
NOTE Typical applied amplitudes and signal durations are provided in ECSS-E-HB-10-12 Section 8.5.9 (Table 9) as a function of semiconductor family type. Note, however, that these are not the only devices to be tested for SET/SED.
b. In case other than requirement 9.4.1.7a, the SET/SED rate shall be predicted using the same methods as for SEU, as specified in clause 9.4.1.2 and 9.4.1.3, including ion or proton test.
9.4.1.8 Heavy ion-, proton- and neutron-induced SEHE
a.
The probability of single hard
errors due to ions shall be
determined by integration of the incident particle differential LET spectrum
over the experimentally determined cross-section of the device, as a function
of LET and angle of incidence.
b. The probability of single hard errors due to protons and neutrons shall be determined by integration of the incident particle differential energy spectrum over the experimentally determined cross-section of the device, as a function of particle energy and angle of incidence.
NOTE ECSS-E-HB-10-12 Section 8.7.4 provides a description of SEHE and considerations that can be significant for the test procedure.