Time-Dependence of Materials and Device Degradation
Degradation is seemingly fundamental to all things in nature. Often this is described as one of the consequences of the Second Law of Thermodynamics—entropy (disorder) of isolated systems will tend to increase with time. The evidence for degradation is apparently everywhere in nature. A fresh coating of paint on a house will eventually crack and peel. The finish on a new automobile will oxidize with time. The tight tolerances associated with finely meshed gears will deteriorate with time. The critical parameters associated with precision semiconductor devices (threshold voltages, drive currents, interconnect resistances, capacitor leakage, etc.) will degrade with time. In order to understand the useful lifetime of the device, it is important to be able to model how critically important materials/device-parameters degrade with time.