Self-Heating Characterization and Extraction Method for Thermal Resistance and Capacitance in HV MOSFETs

Abstract

This letter reports on the self-heating effect (SHE) characterization of high-voltage (HV) DMOSFETs and the accurate extraction of the equivalent thermal impedance of the device (thermal resistance, R/sub TH/, and capacitance, C/sub TH/) needed for advanced device and IC simulation. A simple pulsed-gate experiment is proposed and the influence of its parameters (pulse duration and duty factor) are analyzed. It is demonstrated that in our 100 V DMOSFET, SHE is cancelled by using pulses with duration less that 2 μs and duty factor lower that 1:100. The new extraction method exploits analytical modeling and dedicated extraction plots for thermal resistance and capacitance using the measurements of output characteristics at various applied pulses and the gradual reduction of SHE with pulse duration and duty factor. Both R/sub TH/ and C/sub TH/ are extracted in saturation region considering their dependence on SHE and external temperature. In DMOSFETs, the thermal resistance is shown to be a significant linear function of the device temperature (in our device, R/sub TH/ could increase by more than 100% over 100/spl deg/C). The thermal capacitance appears to decrease with the injected power and shows a plateau at high V/sub D/. SPICE simulations with the extracted thermal network R/sub TH/-C/sub TH/ circuit are finally used to fully validate the proposed method.