Thermal conductivity measurement of amorphous dielectric multilayers for phase-change memory power reduction

Abstract

In this work, we investigate the temperature-dependent thermal conductivities of few nanometer thick alternating stacks of amorphous dielectrics, specifically SiO2/Al2O3 and SiO2/Si3N4. Experiments using steady-state Joule-heating and electrical thermometry, while using a micro-miniature refrigerator over a wide temperature range (100–500 K), show that amorphous thin-film multilayer SiO2/Si3N4 and SiO2/Al2O3 exhibit through-plane room temperature effective thermal conductivities of about 1.14 and 0.48 W/(m × K), respectively. In the case of SiO2/Al2O3, the reduced conductivity is attributed to lowered film density (7.03 → 5.44 × 1028 m–3 for SiO2 and 10.2 → 8.27 × 1028 m–3 for Al2O3) caused by atomic layer deposition of thin-films as well as a small, finite, and repeating thermal boundary resistance (TBR) of 1.5 m2 K/GW between dielectric layers. Molecular dynamics simulations reveal that vibrational mismatch between amorphous oxide layers is small, and that the TBR between layers is largely due to imperfect interfaces. Finally, the impact of using this multilayer dielectric in a dash-type phase-change memory device is studied using finite-element simulations.

A Review of Experimental and Computational Advances in Thermal Boundary Conductance and Nanoscale Thermal Transport across Solid Interfaces

“…The resistance associated with amorphous interfaces can defy the general trends that one would expect from interfaces formed between crystalline solids as discussed in the previous paragraph. This is shown in Figure b (square symbols) for several interfaces formed with amorphous materials that possess conductances that are much higher than the typical values observed for interfaces between crystalline solids . Similarly, for material systems in which electrons dominate interfacial heat flow such as for metal/metal interfaces, the values of h K can be greater than an order of magnitude as compared to the typical phonon‐dominated conductances .…”

Interfacial Defect Vibrations Enhance Thermal Transport in Amorphous Multilayers with Ultrahigh Thermal Boundary Conductance

“…The high TBCs at these amorphous SiC:H/SiOC:H interfaces are in line with those predicted via molecular dynamics simulations (refs. and ), experimentally measured across SiO 2 /Al2O 3 interfaces reported from a single AML at room temperature (≈0.67 GW m −2 K −1 ), and the lower limit to TBC measured across an amorphous SiO 2 /crystalline Si interface . In ref.…”

The Heat Conduction Renaissance

“…Cross-plane phonon transport in superlattices has been studied extensively by several groups over the past two decades [57]- [65]. Recently, there has been a resurgence of interest in this topic, specifically on the question of coherent phonons.…”