Heat Transfer Handbook part 136. The Heat Transfer Handbook provides succinct hard data, formulas, and specifications for the critical aspects of heat transfer, offering a reliable, hands-on resource for solving day-to-day issues across a variety of applications. | 1348 MICROSCALE HEAT TRANSFER voltage and the junction capacitance of the device. While these reductions all represent improvements the insulating layer also decreases the ability of the device to dissipate heat. SOI transistors are an excellent example of a modern microelectronics device in which microscale heat transfer plays an important role in the overall device performance. Ju and Goodson 1999 cover the subject of microscale heat conduction in integratedcircuits in great detail. Figure is a basic schematic of a SOI transistor where the individual components have been labeled. This device is a field-effect transistor which means that when a voltage is applied to the gate a small conductive channei in created in the doped silicon device layer just underneath the gate. This conductive channel allows current to flow from the source to the drain. However the majority of the resistive heating of the device occurs within this channel. This results in highly localized heating in the silicon layer underneath the gate. The presence of the insulating oxide layer forces the thermal energy to propagate through the silicon device layer and then through the metal leads of the source and drain. The thickness of the silicon device layer can be less than 100 nm which is on the order of the mean free path of a phonon in silicon. Several experimental studies have been performed to quantify size effects in thin silicon films. The source and drain lines are made of metallic materials which act like fins moving the thermal energy away from the device Goodson and Flik 1992 . The thickness of these metal leads is currently on the order of several hundred nanometers which is greater than the mean free path of an electron. However as these dimensions continue to diminish continuum models will no longer be applicable. Another interesting thermal effect that occurs in field-effect transistors which falls into the area of microscale heat transfer is nonequilibrium Joule heating. .
