Etching Chemistry Process Optimization of Ethylene Diluted with Helium (CH/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 (N) and ethylene diluted with helium (CH/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 CH leads to the formation of a thinner, weaker polymer with lower chlorine residue compared to the thicker, stronger polymer formed with N. Elemental analysis further highlights significant differences in carbon and oxygen content, with CH-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.