Experimental Demonstration of AlN Heat Spreaders for the Monolithic Integration of Inline Phase-Change Switches

Inline phase-change switch (IPCS) devices were fabricated on top of an AlN heat spreading layer deposited on a thick SiO2 layer. The thick SiO2 emulates the inter-layer dielectric thermal properties that prevent direct integration of IPCS devices at the end of a back-end-of-line CMOS process. The AlN acts as a heat spreading layer, enabling the proper thermal quench rate despite the low thermal conductivity of the oxide underneath. Multiple AlN thicknesses were examined and shown to properly quench the device. Use of this heat spreading layer experimentally demonstrates a substrate agnostic monolithic integration scheme, where IPCS devices can be integrated at the end of any microfabrication process-regardless of the substrate or materials underneath. This is attractive for many CMOS applications, where wafer real-estate is expensive, or in III-V applications, where the wafer thermal properties are poor and vary among different technologies.