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

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.