Etch stopless dual damascene structure and method of fabrication

A method of fabricating an interconnect structure comprising:

• forming an interlayer dielectric having an upper portion and a lower portion over a metal interconnect;
• forming an opening through said upper and lower portions of said interlayer dielectric to expose a portion of said metal interconnect;
• forming a corrosion resistant metal layer in said opening in said lower portion of said interlayer dielectric and on said exposed portion of said metal interconnect;
• forming a sacrificial material in said opening and on said corrosion resistant metal layer;
• forming a trench in said upper portion of said interlayer dielectric wherein said trench is formed in a portion of said sacrificial material filled opening;
• removing said sacrificial material from said opening;
• and
• filling said trench and said opening with a conductive film wherein said conductive film is formed in direct contact with said corrosion resistant material.

An interconnect structure comprising:

• a first metal interconnect formed in a first interlayer dielectric, wherein said first metal interconnect has a top surface which is co-planar with a top surface of said first interlayer dielectric;
• a second interlayer dielectric having a top portion and a bottom portion formed on said first interlayer dielectric and on a portion of said first metal interconnect;
• a second interconnect formed in said top portion of said second interlayer dielectric;
• and
• a via formed in the lower portion of said second interlayer dielectric wherein said via has an upper portion in direct contact with said second metal interconnect and the lower portion in direct contact with said first metal interconnect, wherein said lower portion of said via is formed from a first conductive film and the upper portion of said via formed from a second conductive film wherein said first conductive film is different than said second conductive film.