SOI thermal impedance extraction methodology and its significance for circuit simulation

The buried-oxide in SOI MOSFET inhibits heat dissipation in the Si film and leads to increase in transistor temperature. This paper reports a simple and accurate characterization method for the self-heating effect (SHE) in SOI MOSFET. The ac output conductance at a chosen bias point is measured at several frequencies to determine the thermal resistance (Rth)and thermal capacitance (Cth) associated with the SOI device. This methodology is important to remove the misleadingly large self-heating effect from the dc I-V data in device modeling. Not correcting for SHE may lead to significant error in circuit simulation. After SHE is accounted for, the frequency-dependent SHE may be disabled in circuit simulation without sacrificing the accuracy, thus providing faster circuit simulation for high-frequency circuits.