SH7055S Datasheet, PDF (898/1002 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7000 Series

The reliability of products is estimated on the assumption that products developed for the
automotive sector are used in a tougher environment than products for the consumer and industrial
sectors. The representative failure phenomena of semiconductor devices, such as the dielectric
breakdown of oxide films and electromigration in wiring, constitute wear-out failures. The stress
factors in such failures are the voltage, current, and temperature applied to devices while they are
in use. Since the temperature range for the guaranteed operation of products for use in automobiles
is conventionally −40°C to 85°C, their reliability in terms of the above failure phenomena has to
be confirmed by accelerated life testing at all temperatures in this range. Operation at temperatures
in excess of 85°C leads to failure within a short time, since high temperatures induce failures in
semiconductor devices. Figure 25.2 shows the temperature dependence of semiconductor device
lifetimes. The type of failure in this figure is a wear-out failure, i.e. the dielectric breakdown of
oxide film. According to figure 25.2, the life at 125°C is 1/10 of life at 85°C, and operation at the
higher temperature leads to a correspondingly higher probability of a failure in the field.
Therefore, the reliability of operation at a temperature in excess of 85°C is checked on the
assumption that the period of operation at the upper-limit temperature of the range for guaranteed
operation is 3000 hours.
100
Activation energy 0.6eV
10
1
0.1
0.01
125
85
50
Temperature (ºC)
Figure 25.2 Temperature Reliability of Dielectric Breakdown of Oxide Film
Rev. 2.0, 07/03, page 860 of 960