The term hot-carrier degradation used in this work describes the damage found in MOS devices leading to distortion of device parameters. In the beginnings of hot-carrier investigations, several groups of degradation modes have been differentiated based on the carrier generation mechanisms [222]. The first mode identified in this classification is caused by carriers accelerated by high electric fields along the channel and is called channel hot-carriers. The next type, the substrate hot-carrier generation, is based on carriers injected from the substrate. These carriers are accelerated towards the gate and are considered to be most important in the context of interface and oxide damage. The drain avalanche hot-carriers, especially active at low gate voltages, are generated by single carriers which trigger avalanche carrier generation. The last mode in this classification, is the secondarily generated hot-carrier degradation activated by minority carriers resulting from impact-ionization due to the substrate current. Following this classification, the channel hot-carriers including the avalanche induced secondary carriers are most important in the considerations of this work.
In the first section of this chapter, the most important characteristics of hot-carrier degradation observed in MOS transistors are discussed. The remaining part is devoted to modeling approaches. Section 6.2 gives a selection of common modeling approaches and Section 6.3 finally presents the hot-carrier degradation model recently developed by our group.