Time-dependent drain- and source-series resistance of high-voltage lateral diffused metal-oxide-semiconductor field-effect transistors during hot-carrier stress

In this paper, a new reverse transconductance method for investigating the effect of hot-carrier degradation on high-voltage (HV) lateral diffused metal-oxide-semiconductor field-effect transistors (LDMOSFETs) is presented. This new method can extract asymmetric drain and source series resistance separately with only one single device. By using this extraction method in HV LDMOSFETs before and after the application of hot-carrier stress, drain series resistance is extracted and found to increase while source series resistance remains the same. In addition, the threshold voltage and subthreshold slope suffer no degradation after the application of hot-carrier stress. Therefore, it is suggested that the current degradation in HV LDMOSFETs after the application of hot-carrier stress is not due to the damage under the channel but is due to the drift region under the spacer oxide. This is confirmed by the simulation results of a two-dimensional (2D) simulator. In addition, the differences in hot-carrier degradation between HV LDMOSFETs and low-voltage lightly doped drain (LV LDD) MOSFETs are also discussed in detail.