Environmental performance characterization of atomic layer deposition

Atomic layer deposition (ALD) is emerging as a promising nanotechnology for manufacturing dielectrics and insulators on microelectronics devices. Its environmental performance has to be characterized at this early development stage to achieve sustainable manufacturing in the future. In this paper, we report our environmental performance characterization studies on ALD technology through material flow analysis and energy flow analysis. The assessed ALD process is for deposition of Al₂O₃ high-k dielectric films on a 4 inch silicon wafer. The results show that only 50.4% of input trimethyl aluminum (TMA) material is turned into Al₂O₃ film, while the other half is transformed into toxic emissions into the environment. Material usage efficiency of water is only 2.03% in current ALD processes. ALD is also featured with intensive energy consumption. For the studied ALD process, a total of 4.09 MJ energy is consumed for deposition of a 30 nm Al₂O₃ film, with averaged energy consumption at 13.6 KJ per cycle.