A Novel ‘I-V Spectroscopy’ Technique to Deconvolve Threshold Voltage and Mobility Degradation in LDMOS Transistors

Abstract

Although the CMOS-compatible Laterally Diffused MOSFET (LDMOS) is widely used in various applications as a versatile and efficient power electronic device, its hot carrier degradation (HCD) remains a persistent and important design challenge. None of the classical HCD models apply, because the geometric and doping complexities of the channel and drift regions create multiple hotspots with bias-dependent hot carrier injection into the oxide. To address these challenges, here we: 1) propose a novel geometrical partition of the LDMOS and represent each part by a TCAD-calibrated and experimentally validated tandem-FET compact model; 2) use the new compact model to propose an ` I - V spectroscopy' methodology to deconvolve mobility and threshold degradation in the channel and the drift regions; 3) separate the degradation in the two regions by postprocessing measured I-V curves; 4) demonstrate that ΔV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> determined by classical techniques, e.g., constant current (CC) or maximum transconductance (Gmmax), are contaminated by mobility degradation and must be corrected by the proposed technique for accurate lifetime projection.