Structure and formation method of damascene structure

A semiconductor device, comprising:

• a semiconductor substrate;
• a first conductive feature over the semiconductor substrate;
• a first dielectric layer over the semiconductor substrate and surrounding the first conductive feature;
• a second conductive feature over the first conductive feature, wherein a portion of the second conductive feature is at least partially surrounded by the first conductive feature;
• a second dielectric layer over the first dielectric layer and surrounding the second conductive feature;
• and
• an etch stop layer between the first dielectric layer and the second dielectric layer, wherein a topmost surface of the etch stop layer is between a top surface of the first conductive feature and a bottom surface of the first conductive feature, and the topmost surface of the etch stop layer is substantially planar.

A semiconductor device, comprising:

• a semiconductor substrate;
• a first conductive feature over the semiconductor substrate;
• a first dielectric layer over the semiconductor substrate and surrounding the first conductive feature;
• a second conductive feature over the first conductive feature, wherein the second conductive feature penetrates into the first conductive feature;
• a second dielectric layer over the first dielectric layer and surrounding the second conductive feature;
• and
• an etch stop layer between the first dielectric layer and the second dielectric layer, wherein a topmost surface of the etch stop layer is between a top surface of the first conductive feature and a bottom surface of the first conductive feature, and the topmost surface of the etch stop layer is substantially planar.