Thermal Scaffolding for Ultra-Dense 3D Integrated Circuits

Dennis Rich, Anna Kasperovich, Mohamadali Malakoutian, Robert M. Radway, Shiho Hagiwara, Takahide Yoshikawa, Srabanti Chowdhury, Subhasish Mitra

Abstract: We address the thermal challenge of ultra-dense 3D (e.g., monolithic 3D) integrated circuits with multiple high-speed computing engines in the 3D stack. We present a new thermal scaffolding approach achieved through a combination of (1) new Back-End-of-Line (BEOL)-compatible dielectric materials for simultaneous high thermal conductivity and low dielectric constant, (2) new 3D physical co-design of BEOL dielectrics with thermal metal structures for uniform heat conduction with minimal metal insertion overhead, and (3) previous, experimentally demonstrated heatsink advances. Physical designs of thermal scaffolding enable 12-tier 7nm ultra-dense 3D IC with max temperatures ≤125 degrees Celsius: an iso-footprint, iso-delay, 4x improvement in stacked tiers.