The Study of the Electrothermal Property of High-Voltage Drain-Extended MOSFETs

In this paper, the relation between the surface electric field and the temperature distribution dependence on the drift-region doping concentration in a 30-V asymmetric drain-extended MOSFET is studied. For the case of high drift-region concentration, the drain resistance is low, and the current density is high, which induces a high nonuniform temperature distribution in the transistor, which in turn reduces the carrier mobility and causes a negative drain resistance. For the case of low drift-region concentration, a uniform temperature distribution is obtained. However, the different drift-region concentration changes the location of the maximum temperature from the gate-overlapped drift region for the high concentration case to the drain-side contact region for the low concentration case under the high
$V_{\rm GS}$
and
$V_{\rm DS}$
conditions. Therefore, the self-heating effect is also changed by the redistribution of the electric field in the drift region.