Thermodynamic Degradation Science

7TAT Model Applications: Wear, Creep, and Transistor Aging

7.1 Solving Physics of Failure Problems with the TAT Model

In this chapter we provide examples of the thermally activated time-dependent (TAT) models that include degradation models for wear, creep, transistor aging, as well as dielectric leakage. We include both cases in the instant of field-effect transistor (FET) and bipolar transistors.

7.2 Example 7.1: Activation Wear

There are a number of different types of wear, often characterized by their wear rate [1, 2]. Activation wear is a term we use here to describe wear due to a thermally activated process. This approach offers an alternative to the Archard’s empirical constant-type-wear model discussed in Chapter 4 (see Equation (4.20)). Heat is often an enemy in degradation processes and leads to an acceleration effect in frictional wear. When logarithmic-in-time aging occurs, as is illustrated in Figure 7.1 (often observed in metals), the TAT model can apply. This is characterized by an initially high wear rate followed by a steady-state low wear rate. Archard’s type shows the case of steady wear in time, where the wear rate amount is constant over the sliding distance (Figure 7.1). Log(time) shows the case of an initially constant wear rate, where surface roughness increases to a certain value and does not increase much after that as the wear rate then decreases over sliding distance. The other type of wear is observed in lapping and polishing for surface finishing ...