Investigation of voltage-dependent thermal property in high-voltage drain-extended MOSFETs

In this study, a reduction in the saturation current caused by self-heating effect at high VGS is observed in a 35-V rated asymmetric DEMOSFET. The high VGS -induced the large current and raises up the device surface temperature. The Kirk-effect takes places at sufficiently high current levels (high VGS values) leading to the movement of the maximum temperature point from the gate-overlapped DE (drain-extended) region to the drain-side contact region. The drift-region resistance strongly correlates to the self-heating effect and the VK voltage is proportional to the doping concentration in the drift region. As a result, the reduced surface heating (RESURH) can be realized by the optimization of doping concentration in the drift region.