MIL- STD-883F 2004 TEST METHOD STANDARD MICROCIRCUITS - 第131页

MIL-STD-883F METHOD 1020.1 15 November 1991 3 2.3 Latc hup test syst em . A bloc k diagr am of a typi cal lat chup tes t s ystem i s pres ented on fi gure 1020-1. The inst rumentat ion shal l be capabl e of est ablis hin…

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MIL-STD-883F
METHOD 1020.1
15 November 1991
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h. Radiation pulse width(s), radiation dose(s) per pulse and dose rate range(s).
i. Total dose limit for each device type.
j. Failure criteria.
In addition to those items listed above, the test plan or procedure for production tests shall include the following:
k. Method(s) to detect latchup, e.g., monitoring of the supply current, functional testing (to include test vector set,
etc.).
l. Recovery period and when to begin post-irradiation in-situ tests. The recovery period for SSI devices is typically
50 to 300 µs; however, other device types may require a longer recovery period, or there may be special program
requirements which call for earlier recovery.
m. Functional test requirements. The functional tests shall demonstrate that the device responds properly to input
commands and that the device is operating properly. Note that high speed functional tests may be incompatible
with the long leads and unavoidable capacitance associated with most latchup test systems.
n. Exposure states or operating conditions. For digital devices, a specific state and its complement are usually used.
However, for more complex devices, more than two exposure states may be required, and the specific states
shall be as determined by the characterization testing (and analysis, if required) and specified in the test plan or
procedure.
o. Bias and load conditions. Unless otherwise specified, the maximum rated operating supply voltage shall be used.
p. Outputs to be monitored.
q. The minimum dc current that must be available from the power supply, or the value of series current limiting
resistor that has been approved by the acquiring activity. (Note that any current limiting resistor shall be less than
or equal to that in the system application and shall be approved by the acquiring activity prior to latchup testing.)
2. APPARATUS
. The apparatus shall consist of the radiation source, the dosimetry system, and the latchup test system
which includes the device interface fixture, the test circuit, cabling, timing, and temperature control systems. Precautions
shall be observed to obtain adequate electrical grounding to ensure low noise.
2.1 Radiation source
. Either of two radiation sources shall be used for latchup testing: 1) a flash x-ray machine (FXR),
or 2) an electron linear accelerator (LINAC). The FXR shall be used in the x-ray mode and the LINAC in the electron (e-
beam) mode. The FXR peak (endpoint) energy shall be 2 MeV or greater, and the LINAC beam energy shall be 10 MeV or
greater. The pulse width shall be from 20 to 100 ns, or as specified in the acquisition document, and the uniformity of the
radiation field in the device irradiation volume shall be ±15 percent as measured by the dosimetry system. The dose per
radiation exposure shall be as specified in the test plan or procedure. (See 3.5.1 for production test requirements.)
2.2 Dosimetry system
. A dosimetry system shall be used which provides a measurement accuracy within ±15 percent. A
calibrated PIN diode may be used to obtain both the shape of the radiation pulse and the dose, and the following DOD
adopted American Society for Testing and Materials (ASTM) standards or their equivalent may be used:
ASTM E 666 - Standard Method for Calculation of Absorbed Dose from Gamma or X Radiation.
ASTM E 668 - Standard Practice for the Application of Thermoluminescence Dosimetry (TLD) Systems
for Determining Absorbed Dose in Radiation Hardness Testing of Electronic Devices.
ASTM E 1249 - Minimizing Dosimetry Errors in Radiation Hardness Testing of Silicon Electronic
Devices.
MIL-STD-883F
METHOD 1020.1
15 November 1991
3
2.3 Latchup test system
. A block diagram of a typical latchup test system is presented on figure 1020-1. The
instrumentation shall be capable of establishing the required test conditions and measuring and recording the required
parameters. The test system shall be designed to maintain the instantaneous bias supply voltage within the limits specified
in 2.3.2 below for both transient and dc conditions, including a latchup condition. The test system shall not limit the ac or dc
bias supply current to values that prevent latchup from occurring or being detected. Components other than the device
under test (DUT) shall be insensitive to the expected radiation levels, or they shall be shielded from the radiation. The
system used for latchup testing shall contain the following elements:
2.3.1 Device interface fixture
. The DUT shall be interfaced to the test circuitry with a fixture having good high frequency
characteristics, and providing a low inductance connection to the power supply and bypass capacitor.
2.3.2 Bias and functional test circuit
. The test circuit for each device type shall provide worst case bias and load
conditions for the DUT, and shall perform in-situ functional testing of the DUT as specified in the test plan or procedure.
Line drivers shall be used, when necessary, to isolate the DUT from significant extraneous loading by the cabling. The
characteristics of the line drivers (e.g., linearity, dynamic range, input capacitance, transient response, and radiation
response) shall be such that they do not reduce the accuracy of the test. The power supply shall have low source
impedance and meet the following requirements:
a. The power supply voltage shall drop no more than 20 percent at the DUT during the rise time of the DUT during
the rise time of the DUT supply current, and no more than 10 percent thereafter. These requirements can be
achieved by selecting appropriate capacitance values and minimizing lead lengths of the stiffening capacitors. A
high frequency, radiation resistant capacitor shall be placed at the DUT for each bias supply voltage, and larger
capacitors may be placed a short distance from the fixture shielded from the radiation.
b. DC power supplies shall provide sufficient current for device operation and to maintain holding current if latchup
occurs.
c. Power supplies connected in series with digital ammeters (current probes or current sensors) may be used only if
the ammeter is physically located on the power supply side of the bypass capacitor. The ammeter should be
selected to minimize the series dc voltage drop at the maximum expected load current. If necessary, the power
supply voltage should be adjusted upwards slightly to ensure that the voltage measured at the DUT is within the
specified limits for the test conditions.
d. Current limiting resistors shall not be used in series with the supply voltage unless approved by the acquiring
activity prior to latchup testing, and the value of the resistance is less than or equal to that in the system
application.
CAUTION: Current limiting resistors can produce a relatively narrow latchup window which may reside entirely
outside the standard testing range of 500 ±200 rads(Si). If current limiting is used, especially when used as a
means of latchup prevention, characterization tests shall be performed to determine the dose rate appropriate for
production testing.
If current limiting resistors are used, they shall be placed sufficiently close to the DUT to ensure that the voltage
drop at the DUT during the transient photocurrent rise time is governed by the resistance and not the inductance
from the leads (i.e., voltage drop is approximately IR and not L di/dt). The requirements of paragraphs a-c apply
with the reference point being the power supply side of the current limiting resistor, instead of the DUT supply
pin(s). For applications using small value bypass capacitors directly at the power supply pin(s), the same, or
larger, value of capacitance must be used in the test circuit when current limiting resistors are used. As noted
above, leads shall be kept to the minimum practical lengths.
2.3.3 Cabling
. Cabling shall be provided to connect the test circuit board to the test instrumentation. All cables shall be
as short as possible. Coaxial cables, terminated in their characteristic impedance, should be used if high speed functional
testing is to be performed and line drivers are used to isolate the monitoring equipment.
MIL-STD-883F
METHOD 1020.1
15 November 1991
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2.3.4 Monitoring and recording equipment
. Equipment to monitor and record the parameters required in the test plan or
procedure shall be integrated into the latchup test system. Oscilloscopes and transient digitizers may be used to monitor
the transient response of the device. Additionally, the dose records from each pulse shall be correlated to the specific
device(s) irradiated by that pulse.
2.3.5 Timing control
. An adjustable timing control system shall be incorporated into the latchup test system such that
post-irradiation in-situ functional testing is performed at the specified time, typically 50 µs to 300 µs, after the radiation pulse.
Longer time periods, as long as several minutes, may be required to complete the functional tests for complex devices.
2.3.6 Temperature control
. When testing at other than room temperature, a temperature control system shall control the
temperature of the DUT to ±10°C of the specified temperature. Unless otherwise specified, latchup testing shall be
performed at the highest device operating temperature in the system application or 15°C below the maximum rated
temperature of the device, whichever is less. (See cautionary note below.) If an application temperature is not known, or is
not available, the device shall be tested at 15°C below the maximum rated temperature. Heat sinking may be required to
ensure that the device is not operated above the maximum rated temperature.
CAUTION: The thermal conduction through the latchup test sockets is often much less than that through the pins in
soldered boards.
3. PROCEDURE
.
3.1 Device identification
. In all cases, devices shall be serialized, and the applicable recorded test data shall be traceable
to the individual device.
3.2 Radiation safety
. All personnel shall adhere to the health and safety requirements established by the local radiation
safety officer or health physicist.
3.3 Total dose limit
. Unless otherwise specified, any device exposed to more than 10 percent of its total dose limit shall
be considered to have been destructively tested. The total dose limit shall be determined for each device type to be tested,
and shall be specified in the test plan.
3.4 Characterization testing and analysis
. Characterization tests should be performed on new or unfamiliar device types
to determine their performance as a function of dose rate and to establish requirements for production testing. Because
latchup is dependent on lot to lot variations, samples for characterization tests should be pulled from the production lot(s).
The following are examples of information gained from characterization testing:
a. Latchup threshold as a function of radiation dose, dose rate, and pulse width.
b. Existence and dose rate range of latchup windows. To check for windows, latchup testing is performed over a
wide range of dose rates in fine increments.
c. Worst case or unique conditions that cause the device to exhibit latchup, such as operating voltage, temperature,
and bias conditions.
d. Method(s) to detect latchup, e.g., monitoring supply current, functional testing, or both. Note that in-situ functional
tests must be thorough enough to determine if a small portion of a large circuit has latched without drawing
enough additional current to significantly increase the device supply current.
e. Group A electrical parameter degradation subsequent to latchup testing.
f. Holding current and holding voltage.