Reconstruction of interfacial thermal transport mediated by hotspot in silicon-based nano-transistors

Transistors are typical multi-interface nanostructures, and the heat dissipation problem has become the bottleneck restricting size reduction and performance improvement of semiconductor devices. Local high -temperature hotspot generated by self-heating effects seriously affects the stability and reliability of the devices, and the interfaces further hinder the heat conduction. Thermal analysis is complicated by sub -continuum phenomena which reshapes the hotspot region and interface-mediating. There has been less description of device thermal transport mediated by hotspot coupling with the interfaces. In this paper, based on the phonon BTE (pBTE) thermal solver and electronic Monte Carlo ( e-MC) simulation, we sys-tematically study the thermal transport behavior of 1-D Si transistor and Si-based heterojunction inter-faces under the hotspot effect. Also, the influence of other scattering events is investigated by modifying the relaxation time. Inside hard hotspot, the temperature and heat flux of different phonon modes are decomposed, which shows a strong non-equilibrium effect. The contributions of non-Fourier effects are separated and quantified based on split-flux model. In heterojunction structure, the interfacial thermal resistance further increases the hotspot temperature. Interestingly, on the side of hotspot near the in-terface, the direction of heat flux is opposite to the direction of the temperature drop, which violates Fourier's law. Through different substrate combinations, the heat dissipation effect of diamond, BN is not excellent due to the low interfacial thermal conductance (ITC), time-dependent BTE is used to study the heating rate. Mode-dependent temperature and heat flux reveal nonequilibrium phonon transport per-formance. Finally, the wave-resolved spectral heat flux is calculated to explore the predominant thermal transport channel and interface phonon transport characters. Above studies provide useful insights for further improving the accuracy of transistor-level thermal simulations.(c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

In this study, the thermal transport behavior of a 1-D Si transistor and Si-based heterojunction interfaces under the hotspot effect was systematically investigated. The results showed a strong non-equilibrium effect within the hotspot, with different phonon modes exhibiting different temperatures and heat fluxes. The interfacial thermal resistance of the heterojunction further increased the hotspot temperature. The study also explored the heat dissipation effect of different substrate combinations, revealing that diamond and BN had lower interfacial thermal conductance. These findings provide useful insights for improving the accuracy of transistor-level thermal simulations.