Comprehensive analysis of the degradation of a lateral DMOS due to hot carrier stress

The drift of electrical parameters due to the injection of high energetic ¿hot¿ carriers into the oxide during operation is a serious concern regarding the reliability of lateral double-diffused transistors (LDMOSFETs). This is amplified by down-scaling, increasing the electric field in the drift region and thus the rate of hot carrier generation. As a consequence, profound knowledge of the hot carrier degradation is required for future device designs and the modeling of hot carrier degradation in various application modes. In this work, a comprehensive analysis of the hot carrier degradation at elevated drain voltage in an n-type LDMOSFET is presented. Photo-emission microscopy is used to detect the position of the impact ionization spot. The results are shown to be in good agreement with device simulation using the drift diffusion model and allow explaining the gate-voltage dependence of the degradation of R_on. By Monte-Carlo simulation, the energy and spatial distribution of hot electrons and holes impinging on the oxide interface of an LDMOSFET is calculated.