Area-selective atomic layer deposition of dielectric-on-dielectric for Cu/low-k dielectric patterns

Area-selective atomic layer deposition (AS-ALD) has received a great deal of attention in recent years because of its potential to provide a more robust and controllable fabrication process for next generation electronic devices. In this paper, we study selective deposition of metal oxides on Cu/low-k dielectric patterns. We demonstrate that the inherent growth rate of ALD films is higher on Cu than on low-k surfaces, which indicates the importance of using organic molecules as an inhibitor to prevent ALD growth on Cu surfaces if the goal is to achieve area-selective deposition of materials on lowk surfaces. We show that vapor-phase dodecanethiol (DDT) can be used as an inhibitor. DDT is selectively deposited on Cu surfaces and is effective at ZnO ALD blocking with selectivity greater than 90% after 100 ALD cycles (~17 nm). With the optimization of DDT deposition temperature and Al₂O₃ deposition conditions, the blocking ability of DDT against a more aggressive precursor is further improved and shows selectivity above 90% after 1.5 nm Al2O₃ deposition.