Patent ID: 7378740

Claim:
A dual damascene structure for electrically interconnection to a base metal interconnect structure formed in a semiconductor substrate, which comprises: a first dielectric layer formed from a first low-K inorganic dielectric material over the substrate to cover the exposed surface of the base metal interconnect structure; an etch-stop layer formed from a low-K organic dielectric material over the first dielectric layer; a second dielectric layer formed from a second low-K inorganic dielectric material over the etch-stop layer; a protective layer formed between the etch-stop layer and the second dielectric layer, wherein the material of the protective layer is difference from the material of the etch-stop layer; a metal line formed in the second dielectric layer and the protective layer; and metal plug connected with the metal line and penetrating through the etch-stop layer and the first dielectric layer to come into electrical contact with the base metal interconnect structure in the substrate.