Post-etch residue removal in BCB/Cu interconnection structure

Abstract

This article describes the evaluation of post-etch residue removal after descumming BCB (Benzocyclobutene). BCB is widely used in the electronics industry due to its low tangent loss at the high frequency (tan d=10 −3 at 10 GHz). The BCB film is descummed by brief exposure to plasma after curing. The descumming process is necessary to remove the residue that remains after the developing process. O 2/CF 4, in which the ratio of O 2 to CF 4 is 80:20, has been used as etching gas. It is critical to have the low contact resistance between BCB and Cu in the BCB/Cu interconnecting structure. We have tried a few chemicals to make the surface clean for the low contact resistance and found that the EKC chemical is very effective to clean via surface.