Study on the Properties of Interlayer Low Dielectric Polyimide during Cl-Based Plasma Etching of Aluminum

The properties of polyimide for interlayer dielectric applications are investigated during plasma etching of aluminum on it. Chlorine-based plasma generally used for aluminum etching results in an increase in the dielectric constant of polyimide, while SF6 plasma exhibits a high polyimide etch rate and a reducing effect of the dielectric constant. The leakage current of polyimide is significantly suppressed after plasma exposure. An optimal combination of Al etch with Cl2 plasma and polyimide etch with SF6 plasma is expected to be a good tool for realizing multilevel metallization structures.