Nano-Indentation for Evaluating Low-K Dielectric Adhesion

Low-K dielectric adhesion problems were observed at M1 and M2 levels during thermal cycling of a flip chip product. Nano-indentation of simple BEOL test structures was used to determine the relative strength of the various interfaces in the BEOL stack. It is observed that the weakest adhesion is associated with the initial stages of the SiCOH low-K dielectric deposition. Adhesion loss related to the SiCN etch stop deposition is not observed.