Formation method of damascene structure

A method for forming a semiconductor device, comprising:

• forming a first dielectric layer over a semiconductor substrate;
• forming an etch stop layer over the first dielectric layer;
• forming a first conductive feature extending into the etch stop layer and the first dielectric layer;
• forming a second dielectric layer over the first conductive feature;
• forming a hole in the second dielectric layer to expose the first conductive feature;
• recessing the first conductive feature by partially etching the first conductive feature through the hole;
• and
• forming a second conductive feature electrically connected to the first conductive feature after the first conductive feature is recessed.

A method for forming a semiconductor device, comprising:

• forming a first dielectric layer over a semiconductor substrate;
• forming a first conductive feature extending into the first dielectric layer, wherein the first conductive feature has a planar top surface;
• forming a second dielectric layer over the first conductive feature;
• forming a hole in the second dielectric layer to expose the planar top surface of the first conductive feature;
• partially removing the first conductive feature from the planar top surface of the first conductive feature to form a curved surface of the first conductive feature;
• and
• forming a second conductive feature to fill the hole after the curved surface of the first conductive feature is formed.