A hybrid life cycle assessment of atomic layer deposition process

Atomic layer deposition (ALD), as a key enabling nano-manufacturing technology, has found a wide range of potential applications in a number of industrial sectors. However, due to the binary reaction and self-limiting nature of the ALD process, its life cycle environmental impact is significant but has never been investigated before. This study is conducted using a hybrid life cycle assessment (LCA) approach for evaluating the comprehensive environmental impacts of the ALD process based on the typical ALD of Al2O3 high-k dielectric gate on semiconductors. The hybrid life cycle inventory analysis is conducted using process-based LCA data, economic input–output LCA data, and stoichiometric simulation data for a robust LCA study. The impact assessments are conducted using the TRACI method, with both original and U.S. normalized impact results analyzed. Normalized impact results show that, among the twelve selected impact categories, ALD produces the highest impact in the category of fossil fuels use which is 108 times that of the least impact in air acidification potential. Significant differences are also observed among the environmental impacts of the ALD life cycle stages. The environmental impacts associated with the auxiliary infrastructure, equipment, and tools for ALD operation are intensive mainly due to the slow ALD cycling process. This hybrid LCA study provides a comprehensive data support for understanding the potential environmental impacts of ALD nanotechnology and is useful for sustainable scale-up of the ALD technology in future.