Process advances in plasma photoresist and residue removal with the use of H2O vapor

The benefits of H₂O-vapor, when added to a downstream plasma for post-via etch residue removal is discussed. This paper provides results of the polymer removal effectiveness of a FOx low-k post-via-etch application when H₂O vapor is added to the clean process plasma. Two significant findings are presented: (1) The importance of maintaining a low temperature during the residue removal step in order to prevent the ´hardening´ of the residues, and (2) the benefit of using an intermediate plasma-free step that includes H₂O-vapor, for effective removal. Polymers were observed to separate from the sidewall during processes with the intermediate H₂O vapor step and rendered removable in a subsequent DI water rinse. This resulted in a significant enhancement of the yield, compared to the standard high temperature H₂O-vapor-free process of record.