Interconnection process

An interconnection process, comprising:

• providing a substrate having a conductive region;
• forming a dielectric layer on the substrate;
• forming a patterned metal hard mask layer having a trench opening on the dielectric layer;
• conformally forming a dielectric hard mask layer on the patterned metal hard mask layer and filled in the trench opening;
• defining a photoresist pattern to remove a portion of the dielectric hard mask layer and a portion of the dielectric layer in the trench opening to form a first opening in the dielectric layer;
• removing the photoresist pattern;
• performing a first etching process with use of the patterned metal hard mask layer as a mask to form a trench and a second opening extending downward from the first opening in the dielectric layer in the range of the trench opening of the patterned metal hard mask layer, wherein the second opening exposes the conductive region;
• and
• forming a conductive layer in the trench and in the second opening.