High Thermal Conductivity Insulators for Thermal Management in 3D Integrated Circuits

As physical transistor scaling nears its fundamental limits and many applications are increasingly bottlenecked by memory bandwidth, three-dimensional (3D) integration is a promising avenue for continuing Moore's law. Effective thermal management is crucial to unlocking the full performance benefits of 3D integrated circuits (ICs), due to the difficulty of removing heat from all layers in the 3D stack, and also due to thermal coupling between layers. Here, we explore the limits of passive thermal management in 3D ICs achievable using high thermal conductivity electrical insulators AlN and hexagonal BN (hBN). We show that replacing the thermally-resistive interlayer dielectrics of 3D ICs by high thermal conductivity insulators can greatly reduce the thermal resistance between layers and eliminate many of the thermal challenges of 3D ICs. Moreover, in a memory-on-logic architecture in which thermal insulation between memory and logic is desirable, highly anisotropic insulators such as hBN could be used as a heat spreader to keep both memory and logic dies relatively cool.