Self-aligned dual damascene arrangement for metal interconnection with low k dielectric constant materials and oxide etch stop layer

A method of forming an opening in dielectric interconnect layers in a self-aligned manner, comprising the steps of:

• forming a first dielectric layer over a conductive layer, the first dielectric layer comprising a first low k dielectric material;
• forming an oxide layer on the first dielectric layer;
• patterning the oxide layer to define a first dielectric layer opening pattern;
• forming a second dielectric layer on the oxide layer, the second dielectric layer comprising a second low k dielectric material having different etch sensitivity than the first low k dielectric material to at least one etchant chemistry;
• forming a hard mask layer on the second dielectric layer and creating a second dielectric layer opening pattern in the hard mask layer,
• etching a first opening in the second dielectric layer in accordance with the second dielectric opening pattern in the hard mask layer, wherein the step of etching the first opening includes using a first etchant chemistry that substantially etches only the second dielectric layer;
• etching a second opening in the first dielectric layer through the first dielectric layer opening pattern in the oxide layer, the first opening at least partially overlapping the second opening.