Toward Sustainable Fab Operation: Environment, Cost, and Space Optimization in Semiconductor Manufacturing

Sustainability has emerged as a defining challenge for semiconductor fabs, where enormous energy demand, high-value equipment, and growing spatial constraints converge. Although prior studies have emphasized environmental considerations, they often lack actionable solutions aligned with fab-level operations. This paper advances the concept of the Sustainable Fab, articulated through three dimensions: environmental responsibility, cost efficiency, and optimized space utilization. Environmentally, we demonstrate practical reductions in utility consumption by implementing liquefied natural gas (LNG) flow control schemes and rationalizing hot N₂ delivery without compromising process safety. For cost efficiency, we highlight strategies such as extending the lifespan of legacy vertical-NAND multilayered oxide/nitride layer deposition (MOLD) process tools through targeted retrofits and improving dual tank liquid refill (DTLR) systems to reduce unit counts, thereby lowering both capital investment and sub-fab infrastructure demand. From the perspective of space utilization, we introduce new density-based metrics—equipment station density (ESD) and facility station density (FSD)—to evaluate the transfer of productivity gains from tools to the fab level, and propose form factor–guided equipment designs to mitigate footprint mismatches. Collectively, these strategies provide an integrated framework that embeds sustainability into process, equipment, and facility domains, enabling scalable pathways for long-term competitiveness in semiconductor manufacturing.