In-depth analysis and modelling of self-heating effects in nanometric DGMOSFETs

Self-heating effects (SHEs) in nanometric symmetrical double-gate MOSFETs (DGMOSFETs) have been analysed. An equivalent thermal circuit for the transistors has been developed to characterise thermal effects, where the temperature and thickness dependency of the thermal conductivity of the silicon and oxide layers within the devices has been included. The equivalent thermal circuit is consistent with simulations using a commercial technology computer-aided design (TCAD) tool (Sentaurus by Synopsys).In addition, a model for DGMOSFETs has been developed where SHEs have been considered in detail, taking into account the temperature dependence of the low-field mobility, saturation velocity, and inversion charge. The model correctly reproduces Sentaurus simulation data for the typical bias range used in integrated circuits. Lattice temperatures predicted by simulation are coherently reproduced by the model for varying silicon layer geometry.

► Self-heating effects in DGMOSFETs are modelled for different channel geometries.
► Thermal conductivity of thin films and short channel effects are considered.
► Temperature-dependent thermal resistances are evaluated with thermal circuits.
► Lattice temperatures derived with the model are consistent with those simulated.
► Negative conductance values are not seen for channel thicknesses above 14 nm.