Total ionizing dose (TID)

The cumulative ionizing radiation energy absorbed by a device over time, which gradually shifts its electrical parameters.

ELDRS

Enhanced Low Dose Rate Sensitivity. Greater degradation at low dose rate than at high dose rate for the same total dose, seen in many bipolar and BiCMOS linear and mixed-signal parts.

rad(Si) and krad(Si)

Units of absorbed dose in silicon. 1 rad(Si) is 0.01 gray in silicon; 1 krad(Si) is 1,000 rad(Si).

Dose rate

How fast dose is delivered, for example 10 mrad(Si)/s or 36 rad(Si)/h. Dose divided by dose rate gives exposure time.

Co-60 (cobalt-60)

A radioactive isotope that emits gamma rays at 1.17 and 1.33 MeV, the standard source for TID testing. It has a 5.27-year half-life, so source strength falls about 12% a year.

MIL-STD-883 Test Method 1019

The U.S. military test method for ionizing radiation (total dose) testing of microcircuits, defining several test conditions.

Condition A

The high-dose-rate condition of TM 1019, 50 to 300 rad(Si)/s.

Condition D

The low-dose-rate condition of TM 1019, at 10 mrad(Si)/s or a lower or agreed rate, used to test for ELDRS.

ESCC 22900

The European Space Components Coordination basic specification for total dose steady-state irradiation testing.

Pb/Al filter box

A lead and aluminum enclosure around the devices under test that reduces low-energy scattered radiation, which would otherwise cause dose errors.

Dosimetry

Measurement of the dose and dose rate delivered at the device positions, with calibration traceable to national standards.

Bias

The electrical operating condition applied to a device during irradiation. Bias can strongly affect how much a part degrades.

Anneal

A period after irradiation, at room or elevated temperature, during which some radiation-induced damage recovers or changes.

Rebound test

An extended TM 1019 procedure of additional dose followed by an elevated-temperature biased anneal, applying mainly to MOS devices.

RHA

Radiation hardness assurance. The overall process of making sure parts will survive a mission's radiation environment.

Interim readout

An electrical measurement taken partway through an exposure, at a planned dose level.