Chapter 4. Basic Failure Modes and Mechanisms

GaAs devices exhibit some general failure modes that can be attributed to a defined failure mechanism. The most common failure modes are observed via degradation of the MMIC parameters such as IDSS, gain, POUT, and others. The degradation observed in MMIC devices is normally a function of the material interactions and the environmental conditions during test or operation. The importance of a particular parameter degradation depends greatly on the design and function of the MMIC and the relationship between the observed degradation and the general health of the device in question. A list of the most common failure modes is provided in Table 4-1. Life tests, with RF or dc excitation and performed under controlled conditions, are the most common means of failure-mode detection. These tests can provide valuable information as to the type of degradation to which the particular device under test may be most susceptible, and the severity of the effect on the performance of the device.