Hot-carrier reliability in high-voltage lateral double-diffused MOS transistors

With the continuing scaling of metal-oxide-semiconductor (MOS) devices, the hot-carrier (HC)-induced device degradation has become a major reliabiliy concern in sub- and deep-submicrometre MOS field-effect transistors (MOSFETs) and lateral double-diffused MOSFETs (LDMOSFETs). It is believed that the degradation is mainly due to the effects of the generated oxide-trapped charges and interface traps at the Si/SiO₂ interface. In general, the large electric field is strongly localised in a well-defined region; therefore carrier injection and interface-trap creation are similarly concentrated. The strongly inharmonious characters of HC injection and resulting damage present a considerable challenge to both experimental and modelling efforts.The HC degradation behaviour of an n-channel LDMOS transistor is investigated under various stress conditions. By applying variable base charge pumping experiments, a consistent picture of the degradation mechanism can be depicted. HC-induced interface traps are generated in the channel region of the device, in the drift region below the thick field oxide and at the bird´s beak edge. The latter is shown to dominate the degradation of I _dlin, which is the most critical parameter concerning HC lifetime in this specific device.