For companies and organizations in the space industry, being able to protect integrated circuits from radiation damage is a major focus. The ionizing radiation effects that integrated circuits experience cover the spectrum from minor to destructive. Key to protecting equipment on spacecraft is understanding how radiation interacts with integrated circuits.
Discovery of Radiation Effects on Electronics in the 1950s and 1960s
Scientists discovered the negative effects of radiation on electronics when they conducted above-ground nuclear bomb tests in 1954. They observed various malfunctions and damage in measuring equipment and recognized that it was from the energy released by the explosions—gamma rays, neutrons, electrons and alpha particles. In particular, neutron-generated single event effects (SEEs) caused temporary problems with electronics and gamma radiation produced permanent damage to equipment.
This led to the question, “At what point does radiation damage electronics?” It also spawned the field of radiation effects testing, including displacement damage testing on integrated circuits.
Researchers learned more about radiation effects on electronic components and circuits in the 1960s when satellite equipment, and later equipment used in space exploration, was operated in a space radiation environment. One of the challenges with satellites was determining whether communication errors were caused by radiation or other factors.
Radiation Effects on Electronics Can be Grouped into Two Categories
Radiation effects on electronics in space can be grouped into two categories: ionizing effects and non-ionizing effects (also referred to as displacement damage). What radiation effects occur are a function of the particle type, the charge state, the energy, and other things like even the trajectory of the particle at times.
Obviously, damage of any kind to integrated circuits used in space is problematic, as repairs are difficult at best, and in many cases, impossible.
The Solution: Radiation Hardening
Radiation hardening can help protect integrated circuits from ionizing and non-ionizing radiation (in the form of particle radiation and high-energy electromagnetic radiation) damage in space. Radiation-hardened components or “rad-hard components” are designed specifically to resist ionizing radiation effects. Radiation-hardened integrated circuits can function reliably in the space environment, ensuring that the devices they are used in operate properly. Often times the radiation hardening is dependent upon how the device is used in the system and the end user must implement the device correctly to get the expected radiation tolerance out of the design.
This is critical in many types of sensors and devices used by aerospace and military organizations. Results that are unintelligible or even just inaccurate can render this equipment unusable.
Testing of Radiation-Hardened Integrated Circuits
Just as important as the development of radiation-hardened integrated circuits is the testing of those circuits. Radiation damage can occur in an instant or over time, so it is vital that rad-hard components are thoroughly assessed to ensure they can handle the function for which they were designed accurately and without interruption.
Even a single failure can cause the malfunction of a costly rocket, satellite, space probe or other equipment used in space or other harsh radiation environments, and in the case of manned missions, put lives at risk. Consequently, a “learn before you launch” approach to radiation effects testing is key.