Integrated power-management ICs are often used in high-power systems such as radar and satellites. These lightweight devices can replace older modules and provide better power efficiency. But failure in space is not an option, because there is no human around to make repairs. Testing can help assure that the devices will withstand radiation.
In space, electronic components are subject to radiation that can damage MOSFET, BJT, or IGBT on a power-management IC. Radiation failures can cause the entire IC, and thus the entire system, to fail.
There are four major sources of radiation: electrons, protons, heavy ions, and gamma rays. Each radiation source can cause a SEE (Single Event Error). The cause of a SEE is the interaction of the radiation source with the electrons of the silicon electron cloud (see Figure 1). Radiation can impact an IC by altering its silicon structure. That must be prevented from becoming a permanent failure or, in the worst case, a disruptive event.
The radiation sources causing the failures of a SEE: the displacement damages caused by an electron impacting a silicon semiconductor material, having low (a) or high (b) energy. In case (a) the electron snatches one electron during the impact. In case (b) the electron interacts with the electrical field of the nucleus and emits a photon. In case (c) a proton or a heavy ion interacts electrically with the electrons of the silicon electron cloud and creates a hole h+ that is a spot where electrons are missing.
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A SEE failure in an integrated component of an IC can be caused by the modification of the threshold voltage of a MOSFET inside a chip. This variation is due to the recombination of holes trapped in the gate oxide and electrons flowing inside the source-drain channel when the transistor is on the ON state (see Figure 2).
Recombination of holes trapped in the gate oxide and electrons flowing inside the source-drain channel may cause a variation of the threshold voltage, and a SEE may occur.
Proper design of testing procedures can minimize SEE failures. On the next page, I'll describe how an automated testing procedure of an IC component used in aerospace applications can account for the effects of the radiation.
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