Analysis of Thermal Resistance Considering Self-Heating Effects and Ambient Temperature Coupling for Double-SOI MOSFETs

In this article, the influence of self-heating effects (SHEs) and ambient temperature coupling on the thermal resistance of double silicon-on-insulator (SOI) MOSFETs was investigated by experiment and simulation methods. A simple and efficient measurement technique, namely, the bulk–source diode method, was used to extract the thermal resistance of double-SOI (DSOI) devices at different ambient temperatures. The experimental results show that the thermal resistance of DSOI MOSFETs decreases with increasing ambient temperature, which is different from conventional MOSFET devices. To further analyze the results, the analytic models of SOI thermal conductivity, silicon dioxide buried oxygen (BOX) layers thermal conductivity, and thermal contact resistances (TCRs) were developed and applied in the technology computer-aided design (TCAD) numerical simulations to assess the impact of different regions on the thermal resistance of DSOI devices. The simulation results show that although the thermal conductivity of the silicon substrate and SOI films decreases with increasing temperature, this variation has a limited effect on the thermal resistance of the device. In addition, since the two low thermal conductivity BOX layers isolate most of the thermal diffusion from the channel to the substrate, the TCRs of the top layer have a significant impact on the device's thermal resistance.