Self-Assembled Monolayers for the Polymer/Semiconductor Interface with Improved Interfacial Thermal Management

Abstract

Reliability and lifespan of highly miniaturized and integrated devices will be effectively improved if excessive accumulated heat can be quickly transported to heat sinks. In this study, both molecular dynamics (MD) simulations and experiments were performed to demonstrate that self-assembled monolayers (SAMs) have high potential in interfacial thermal management and can enhance thermal transport across the polystyrene (PS)/silicon (Si) interface, modeling the common polymer/semiconductor interfaces in actual devices. The influence of packing density and alkyl-chain length of SAMs is investigated. First, MD simulations show that the interfacial thermal transport efficiency of SAM is higher with high packing density. The interfacial thermal conductance (ITC) between PS and Si can be improved up to 127 ± 9 MW m–2 K–1, close to the ITC across the metal and semiconductor interface. At moderate packing density, the SAMs with less than eight carbon atoms in the alkyl chain show superior improvements over those with more carbons because of the assembled structure variation. Second, the time-domain thermoreflectance technique was employed to characterize the ITCs of a bunch of Al/PS/SAM/Si samples. C6-SAM enhances the ITC by fivefolds, from 11 ± 1 to 56 ± 17 MW m–2 K–1. The interfacial thermal management efficiency will weaken when the alkyl chain exceeds eight carbon atoms, which agrees with the ITC trend from MD simulations at moderate packing density. The relationship between the SAM morphology and interfacial thermal management efficiency is also discussed in detail. This study demonstrates the feasibility of molecular-level design for interfacial thermal management from both the theoretical calculation and experiment and may provide a new idea for improving the heat dissipation efficiency of microdevices.

Liquid Metal Composites with Enhanced Thermal Conductivity and Stability Using Molecular Thermal Linker

“…Of these sources of interfacial resistance, the value of r Cu‐Silane should be relatively smaller because of the strong covalent SiOCu bonding between copper and silane. [ 42,48 ] Besides, the short and well‐aligned silane molecules are usually of high thermal conductance and contribute negligibly to the whole thermal interface resistance. [ 49–51 ] Consequently, we expect r Silane‐Ga2O3 to play a key role in the interfacial thermal resistance between Cu and Ga 2 O 3 inside the EGaIn‐CuP@Cl system.…”

Molecular Structure Effect of a Self-Assembled Monolayer on Thermal Resistance across an Interface

“…The SP 2 bead represents "Au-S", and SNO bead represents a "-CH 2 -CH 2 -O-" or "CH 2 -CH 2 -OH" group. We chose 32 beads in a SAM chain to avoid the chain length effect on the thermal resistance [10]. During the simulations, SAMs were grafted to the left-or right-side surface of the gold layer through covalent bonds with a grafted density of 3.4 chains/nm 2 .…”

“…These studies have investigated the effects of various characteristics of SAMs on the interfacial thermal conductance from two different points of view: (1) considering accurate information about SAM, including SAM coverage [4,9,10], length of SAMs [4,[11][12][13], distinct functional group [9,[13][14][15][16][17], heterogeneous fin structure [18], vibrational spectral overlapping [9], nanoscale roughness [19][20][21], and so on. Huang et al [16] investigated interfacial thermal conductance (ITC) across the interface of water and gold tailored with -CH 3 SAM, -OHSAM, and -COOHSAM.…”

“…They found that the ITR between gold and water remained constant regardless of the density of SAM. Lu et al [10] investigated the effects of packing density and alkyl-chain length of SAMs on the ITC between the gold and polyethylene (PE) interface by experiments and molecular dynamics (MD) simulations. They concluded that, for a SAM with a high packing density, when the chain of the SAM reached a certain length, the ITC became stable.…”

A brief review of thermal transport in mesoscopic systems from nonequilibrium Green's function approach

“…Recently, interfacial phonon transports have been extensively studied across the interfaces based on various nanostructures such as single-molecule junctions [57][58][59] , self-assembled monolayer interfaces [60][61][62] , one-dimensional nanotube junctions 63,64 , and twodimensional heterojunctions [65][66][67][68][69] .…”