Session: 08-01: Micro/Nanoscale Heat Conduction

Paper Number: 131873

131873 - Thermal Conductivity Characterisation and Quantification of Solid Dielectrics in Nano/micro Scale Thin Film Systems 

Abstract: 

Metal oxide semiconductor field effect transistor (MOSFET) is a building block of integrated circuits (ICs) and transistors. The gate in MOSFET is built of semiconductors, generally Si, and an amorphous insulating layer. The insulating dielectric layer provides electrical insulation among the metallic, p-doped, and n-doped regions thus preventing direct charge flow between the channel to the gate and vice versa. However, the amorphous insulating layer also hinders heat dissipation and affects the performance of such nano/micro systems. Crystalline dielectrics are better for thermal management in thin films due to higher thermal conductivity, κ than amorphous counterparts. Therefore, reliable and accurate quantification of thermal conductivities of solid dielectrics in nano/micro thin film systems is critical to developing high-performance integrated circuits and transistors. Equilibrium molecular dynamics (EMD) is a powerful tool for investigating the mechanical, thermal, and structural properties of materials due to the availability of numerous empirical potentials developed to model atomic interactions. However, not all empirical potentials can predict thermal properties accurately, and the deviation between simulation and experimental results persists for commonly used dielectrics in thin film systems. Thus, equilibrium molecular dynamics (EMD) with the Green-Kubo (GK) approach, suffer from the selection of interatomic potentials. Conventional EMD/GK also becomes inadequate for bonded atoms with different masses as the Heat Current Autocorrelation Function (HCACF) decays differently compared to a monoatomic system. In this study instead of the conventional scheme to average the HCACF integral, a novel approach is proposed targeting only converged HCACF region eradicating substantial statistical error. This study aims to establish a modified EMD-GK approach to reliably and accurately quantify the thermal conductivities of some important solid dielectrics including quartz, sapphire, and Wurtzite AlN. Applying the modified EMD-GK approach, Thermal conductivity in crystalline silica with EMD-GK is successfully investigated. For crystalline silica, ReaxFF SiO is the best potential to be used at 300 K but fails at higher temperatures due to the poor description of high-frequency phonon bands. At a higher temperature greater than 700K, the BKS potential is found to be better. In the case of sapphire, when the system size is about 6 nm, the first-principle calculation makes better predictions than the systematic EMD-GK. For a larger system size, however, the latter is more accurate and efficient. Meanwhile, the Vashishta potential has been found to be the best available potential to investigate the thermal conductivity of sapphire at the classical temperature range of 300 - 1000 K. It was also found that the uncertainty in the selection of empirical potentials can be eradicated by validating potentials against experimental thermal conductivity, atomic energy, atomic structure, and phonon properties.

Presenting Author: Ehsan Khaled Bureau Veritas

Presenting Author Biography: Dr Ehsan Khaled, a passionate Naval Architect, is currently working as a Senior Naval Engineer in Bureau Veritas to develop Naval Classification Rule for the Royal Australian Navy (RAN). He has been working in Australian defence sector since 2018 and have experience to manufacture rigid inflatable boats (RHIBs) and look after seaworthiness of largest Australian Naval platforms, Landing Helicopter Dock (LHDs) HMAS Adelaide and HMAS Canberra.

In his past life, he was a researcher and has a PhD from UNSW in Mechanical and Manufacturing Engineering, where he worked on thermal conductivity optimisation in thin film systems. He has also researched on marine accident prevention and ship roll stabilisation by anti-roll tanks.

He is a proud father of two young kids and have a lovely wife.

Authors:

Mohammad Ehsan Khaled Consultant (unaffiliated)
Liangchi Zhang Soutehrn University of Science and Technology