Concept · Reliability & Quality
Total ionising dose
The energy that ionising radiation deposits in a chip's materials, building up over the whole mission. It slowly shifts transistor behaviour and raises leakage, so a part is specified and tested to the dose its mission will deliver.
- Also known as
- TID, Total ionizing dose
- Type
- Concept
- Domain
- Reliability & Quality, Radiation and soft errors
Overview
Total ionising dose is one of the main ways radiation degrades electronics. Charged particles and photons passing through a chip leave charge trapped in its oxides and at their interfaces. The effect is cumulative: the longer the mission and the harsher its environment, the more dose the part receives.
How it works
Trapped charge in gate and isolation oxides shifts transistor threshold voltages and opens leakage paths, for example along the edges of isolation regions. Analog circuits see offset, gain and reference drift; digital circuits see higher supply current and, in the end, timing failures.
Dose is expressed as energy absorbed per unit mass of material. A part is tested by exposing samples to a radiation source at a controlled rate and measuring its parameters before, during and after exposure, usually with bias applied as in use. Some bipolar and linear technologies degrade more at low dose rates, which the test plan must allow for.
Design answers include hardened processes, layout that removes edge leakage paths, and margins on analog and timing paths sized for the dose expected at the end of the mission.
Examples
- A voltage reference whose output drifts as dose builds up in orbit.
- Supply current that rises on a digital part after exposure.
- A dose budget that gives each analog block a margin for end-of-mission drift.
- Radiation lot acceptance on samples from each wafer lot.
Why it matters
Radiation effects engineers set the dose requirement from the mission profile, designers build margins for it and radiation testing proves it. On the space lifecycle it shapes the hardening approach, the dose budget in the architecture, the radiation testing stage and, for some quality levels, radiation lot acceptance.
It matters most to: Radiation Effects Engineer, Radiation-Hardened Analog Designer, Reliability Qualification Engineer
Common confusions
- Not the same as Single event effect
- Dose builds up over time and degrades a part gradually; a single event effect is caused by one particle at one moment. Total ionising dose vs Single event effect
- Not the same as Displacement damage
- Displacement damage comes from particles knocking atoms out of the crystal lattice and mainly affects bipolar, optical and sensor devices; total ionising dose comes from charge trapped in oxides.
Related standards
- MIL-STD-883 (test method standard for microcircuits, including a total dose test method)
- ESCC 22900 (total dose steady-state irradiation test method)
Sources
- ECSS-E-ST-10-12C Methods for the calculation of radiation received and its effects, and a policy for design margins (opens in a new tab), European Cooperation for Space Standardization (hypertext edition hosted by SPENVIS, ESA), 2026-11-10
- Electronic Radiation Characterization Project (ERC) (opens in a new tab), NASA Electronic Parts and Packaging Program, 2026-11-10
- Radiation Effects and Analysis (opens in a new tab), NASA Goddard Space Flight Center, Engineering and Technology Directorate, 2026-11-10
Related terms
Part of the Reliability & Quality glossary, with every term in the topic and the lifecycles, tools and standards that use them.
Where it appears on the Hub
Used on 5 pages of the Hub. In each group, the pages that mention it most come first.
Lifecycle stages and gates
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