A model for hot-carrier degradation in nLDMOS transistors based on the exact solution of the Boltzmann transport equation versus the drift-diffusion scheme

We present two schemes for carrier transport treatment to be used with our hot-carrier degradation (HCD) model. The first version relies on an exact solution of the Boltzmann transport equation (BTE) by means of the spherical harmonics expansion (SHE) method, whereas the second one uses a simplified drift-diffusion (DD) scheme to avoid the computationally expensive SHE approach. We use both versions of the model to simulate the change of the characteristics of an nLDMOS transistor subjected to hot-carrier stress and compare these theoretical degradation traces with the experimental ones. The similarity in the results of the SHE- and DD-based models together with the flexibility of the latter approach makes it attractive for fast and predictive HCD simulations for LDMOS devices.