Integrated analog ICs are often utilized in aerospace applications to reduce the dimension of power management modules that are inserted, for example, in space stations or satellites.
Complex integrated circuits increase the density of devices that can be inserted in the aerospace modules, and they enhance the scenario of possible functionalities in these very efficient aerospace electric modules. The main goal of the aerospace application engineering team is to ensure a zero failure condition.
In several of my blogs, I've described the damages that radiation sources -- electrons, protons, heavy ions, gamma rays -- may cause. Radiation is present in the open space environment (see Figure 1 below). It can create some failures in the elementary components of a power management IC (i.e., MOSFET, BJT, IGBT) and, consequently, in the whole IC.
The radiation sources causing the single event error: cosmic rays, solar particles,
and protons trapped in magnetic fields.
The sources of radiation are the causes of failures in the integrated circuits for aerospace applications. Now let's consider the effects of these failures of a part of the circuitry on the overall functionality of a complex integrated system on a chip. The main relevant failures that may occur in an aerospace application integrated board are known as single event errors (SEEs) and are caused by two of the four radiation sources of the aerospace environment: the protons and the heavy ions, as shown in Figure 2 below.
The mechanism of the single effect event caused by protons and heavy ions.
(Source: ESA Microelectronics)
The mass of these radiation particles is not negligible compared to the atom's dimension; hence, this radiation can cause displacement damage in the silicon structures.
These particles create electrical charges all along their path, so the radiation sources generate parasitic currents inside the material they cross. These currents generate disturbances that can lead to functionality losses. These losses may be temporary or permanent, but either way, the whole integrated system will be corrupted because of the interconnections among the different blocks.
There are several types of single events:
- Single event latchup
- Single event upset
- Single event transient
- Single event burnout
- Single event functional interrupt
- Single event gate rupture
In addition, post-irradiation gate stress may occur during the electrical stress of the gate oxide of, for example, a power MOSFET by means of a reverse bias testing procedure and the gate oxide breakdowns.
Beginning in part 2 of this series, I will describe in deeper detail the single events listed above. Have you experienced SEEs? If so, what kind did you experience? What do you think about the importance of providing a SEE screening for the IC to be utilized in radiation hard applications?