SOI MOSFET thermal conductance and its geometry dependence

SOI MOSFETs are susceptible to the local thermal heating generated in the channel due to the lesser thermal conductivity of their buried oxide. Even with a ~100 nm thin buried oxide, SOI MOSFET DC I-V characteristics, from which SPICE parameters are extracted, show current loss due to the self-heating. On the other hand, for most logic circuits in an LSI, the self-heating effect is insignificant. Since the average power per device is low and the switching time (~10 ps) is much shorter than the thermal constant (~100 ns), the device temperature increase due to the self-heating is quite small. Therefore, for an accurate circuit design, we must correct the DC I-V data for the self-heating. In this paper, the thermal dissipation paths in SOI MOSFETs are investigated via experiments and modeling