Thermal Management in Ni/Al Reactive Multilayers: Understanding and Preventing Reaction Quenching on Thin Film Heat Sinks.

Thermal management is conventionally the design of microelectronics circuitry to maximize heat extraction and minimize local heating. In this work, we investigate a reverse thermal management problem related to understanding and preventing heat dissipation during the propagation of a self-sustained reaction in Ni/Al reactive multilayers, metastable nanostructures that can release heat through a self-sustained propagating exothermic reaction. While it was recently demonstrated that reactive multilayers can serve as on-chip heat sources for on-demand healing of metal films, they still face challenges of device integration due to conductive heat losses to the substrate or adjacent on-chip components, which act as heat sinks and consequently quench the reaction. Here, we study the impact of different heat sink materials, such as gold, copper, and silicon, on the propagation velocity and temperature of the self-sustained heat wave and show that the propagation can be controlled and even stopped by varying the heat sink thickness. Further, we demonstrate that the introduction of a multilayered Al2O3/Zr/Al2O3 thermal barrier enables stable propagation on substrates that would otherwise quench the reaction. The results of this study will facilitate the integration of Ni/Al multilayers as intrinsic heat sources on different substrates for applications in micro/nanodevices.