Radiation Environments
Reliability and Radiation Effects on Advanced CMOS Technologies




Nearly every chip is hit by some sort of radiation. Not even a circuit protected by several meters of concrete can be safe, since alpha particles can originate inside the chip due to radioactive contaminants.

Terrestrial Environment

The terrestrial environment is characterized by a constant flux of neutrons, originating from the interactions of cosmic rays with the outer layers of the atmosphere. The neutron flux grows with altitude and depends on latitude. At New York City the flux is about 14 neutrons per square centimeter per hour.

Neutrons do not directly ionize silicon, but may trigger nuclear reactions that produce heavy ions capable of generating single event effects inside semiconductor devices.

Besides the threat coming from neutrons, alpha particles may be released by radioactive contaminants inside the chip package or solder materials. Unfortunately, these contaminants cannot be eliminated without incurring in extremely high costs.


The space radiation environment is characterized by a great variety of particles with energies ranging from some keV to several GeV. There are four main components:

  • Trapped radiation: charged particles trapped in the Earth's magnetic field, forming the radiation belts.
  • Cosmic Rays: high-energy particles whose origin is still debated.
  • Solar flares: particles produced by solar eruptions.
  • Plasma of electrons and protons: low-energy electrons and protons which pervade space.

High Energy Physic Experiments

High energy physics experiments require the read-out electronics to work under extremely harsh conditions.

Nuclear Power Plants

Nuclear power plants are another harsh environment from the standpoint of radiation.


Space environment Information System by ESA



The neutron flux at New York City is 14 neutrons per square centimeter per hour

The alpha flux due to contaminants in the chip materials is about 0.001 apha particles per square centimeter per hour