Method for forming copper wiring in semiconductor device

1. A method comprising:

depositing a lower insulating film over a semiconductor substrate;

forming vias in the lower insulating film;

depositing tungsten over the entire surface of upper portion of the lower insulating film so that the vias are gap-filled with the tungsten;

forming tungsten plugs by performing a tungsten chemical mechanical polishing process to remove excess tungsten deposited over the upper portion of the lower insulating film;

removing the tungsten remaining over the upper portion of the lower insulating film by performing a tungsten etchback process;

depositing an upper insulating film over the upper portion of the lower insulating film;

exposing upper portions of the tungsten plugs by forming trenches on the upper insulating film;

depositing copper over the entire surface of the upper insulating film so that the trenches are gap-filled with the copper; and

planarizing the copper over the upper portion of the trenches.

2. The method of claim 1 , wherein the tungsten chemical mechanical polishing process immediately stops polishing when the lower insulating film is detected.

3. The method of claim 1 , wherein the lower insulating film acts as a polishing stopper.

4. The method of claim 3 , wherein the lower insulating film is detected using an optical endpoint detector.

5. The method of claim 1 , wherein the tungsten etchback process is performed in a fluorine-family gas atmosphere.

6. The method of claim 5 , wherein the fluorine-family gas is ClF 3 .

7. The method of claim 5 , wherein the fluorine-family gas is NF 3 .

8. The method of claim 1 , wherein over-etching in a range of 3% to 5% is performed during the tungsten etchback process.

9. The method of claim 1 , wherein the trenches are formed over the upper insulating film by performing an etching process.

10. The method of claim 1 , wherein the trenches are formed over the upper insulating film by performing a reactive ion etch process.

11. The method of claim 1 , wherein depositing tungsten over the entire surface of upper portion of the lower insulating film is carried out using high density plasma chemical vapor deposition.