Characterizing Via Bottom Integrity in Cu/Low‐κ Processes

One of the most challenging aspects of Cu damascene fabrication is obtaining uniformly clear via hole bottoms following etch and clean. Residues and excess CuOx growth are common sources of high resistance and electro‐migration failure. In this paper we describe a method of characterizing via bottoms in dense 0.12 um via structures that have been etched and cleaned prior to barrier/seed deposition. The technique used in this study is a non‐destructive laser measurement method that is sensitive to the absorption of residues and oxides in the via bottom.