Etching Chemistry Process Optimization of Ethylene Diluted with Helium (C₂H₄/He) in Interconnect Integration

This study explores the effects of different passivation gases on the properties of polymers formed on aluminum (Al) sidewalls during the etching process in Al-based interconnect structures. The research compares the use of nitrogen (N₂) and ethylene diluted with helium (C₂H₄/He) as passivation gases, focusing on the resulting polymer's composition, thickness, and strength, as well as the levels of residual chlorine post-etch. The findings reveal that using C₂H₄ leads to the formation of a thinner, weaker polymer with lower chlorine residue compared to the thicker, stronger polymer formed with N₂. Elemental analysis further highlights significant differences in carbon and oxygen content, with C₂H₄-based polymers exhibiting lower carbon and higher oxygen levels. These results underscore the critical impact of passivation gas choice on the etching process and the integrity of Al-based interconnects, offering valuable insights for optimizing metal etching processes in semiconductor manufacturing.