Thermal performance of nano-scale SOI and bulk FinFETs

Self-heating effects of sub-20-nm fin-shaped FET (FinFET) technologies are studied and analyzed in this work using well-calibrated TCAD 3-D electro thermal simulations. We show that the thermal performance characteristics can be accurately measured from the ac capacitance method using simple extraction techniques. The extracted thermal time constants are in nanoseconds range, and show a decrease with scaling. This is because of the increase in the surface area to volume ratio of the fins in FinFETs. The thermal resistance decreases with increase in the input power owing to the spread of the heated volume. Bulk FinFETs have a less thermal resistance as compared with SOI FinFETs because of the effectiveness of its lower fin region. Thermal resistance increases with reduction in fin pitch and increase in the number of fins. Drain current degradation because of self-heating effects, decreases with scaling. This is because the threshold voltage dependence on temperature dominates the mobility or saturation velocity dependence.