scope:

The main reason for accelerated testing is the requirement for power electronic devices for high reliability, according to the respective application, and, therefore, to attain very low failure rates. Without accelerated testing any experimental validation of such low failure rates would be impossible.

Power electronic devices that are vulnerable to terrestrial cosmic radiation include power MOSFETs and JFETs, power diodes and IGBTs (Insulated Gate Bipolar Transistors), which are usually employed for power switching and power conversion. They also include GTOs (Gate Turn-Off Thyristors) and Thyristors. Power devices may be with or without control logic and the may be components of integrated circuit. The maximum rated blocking voltage is higher than 300V (see note 2). Power devices may be based on Si, SiC and GaN technologies.

This test method defines the requirements and procedures for terrestrial destructive (see note 1) single-event effects (SEE) for example, single-event breakdown (SEB), single-event latch-up (SEL) and single-event gate rupture (SEGR) testing . It is valid when using an accelerator, generating a nucleon beam of either

• Mono-energetic protons or mono-energetic neutrons of at least 150 MeV energy, or

• Neutrons from a spallation spectrum with maximum energy of at least 150 MeV

This test method does not apply to testing that uses beams with particles heavier than protons.

This specific choice of nucleon beam energies is stipulated by the mechanism of power device failure due to terrestrial cosmic radiation. Terrestrial cosmic rays [4] result from extended air showers created by the collision of highly energetic particles of the primary (galactic) cosmic radiation and consist mostly of photons and electrons, muons, pions and nucleons, i.e., protons and neutrons. At sea level about 95% of the strongly interacting particles are neutrons.

For SEB to occur in a power device, e.g. a power diode, a nuclear collision between a neutron or proton and a silicon nucleus has to create highly-ionizing spallation fragments which in turn will generate a dense plasma of electron-hole pairs within the semiconductor material. If the local plasma density is high enough this will initiate massive carrier multiplication by impact ionization. Resembling discharge in gases, a "streamer" will sweep through the device which will be filled with carriers and short-circuited, as a consequence. Thermal destruction of the power device might ensue [5].

This mechanism is in contrast to the failure modes in microelectronic storage devices, SRAMs or DRAMs, where SEU are related to the radiation-induced charging or discharging of storage cells, and which are non-destructive.