Semiconductor device and method for forming a metal line in the semiconductor device

1. A method of forming a metal line in a semiconductor device, comprising:

forming a metal layer on a semiconductor substrate;

forming a groove in an upper surface of the metal layer by etching the metal layer;

etching the metal layer so as to form a lower metal line having a width greater than a width of the groove;

forming an insulator layer covering the semiconductor substrate and the lower metal line;

etching the insulator layer to form a contact hole exposing at least part of the groove and a top surface of the lower metal line; and

forming a contact electrode filling the contact hole and an upper metal line connected thereto above the insulator layer.

2. The method of claim 1 , wherein the metal layer has a thickness of about 4,000 Å-6,000 Å.

3. The method of claim 1 , wherein the groove of the metal layer has a depth of about 500 Å-1,500 Å.

4. The method of claim 1 , wherein the metal layer comprises aluminum (Al) and/or titanium nitride (TiN).

5. The method of claim 1 , wherein etching the metal layer comprises plasma etching the metal layer with a gas comprising BCl 3 and/or Cl 2 at an etch selectivity at least 1:1 with respect to an overlying photoresist.

6. The method of claim 5 , wherein:

the metal layer has a thickness of about 4,000 Å-6,000 Å; and

the groove of the metal layer has a depth of about 500 Å-1,500 Å.

7. A semiconductor device, comprising:

a semiconductor substrate;

a lower metal line on the semiconductor substrate and having a groove at a top surface thereof;

an insulator layer above the lower metal line having a contact hole therein exposing at least a part of the groove and a top surface of the lower metal line;

a contact electrode in the contact hole; and

an upper metal line in contact with the contact electrode.

8. The semiconductor device of claim 7 , wherein the lower metal line has a thickness of about 4,000 Å-6,000 Å.

9. The semiconductor device of claim 8 , wherein the lower metal line comprises aluminum (Al) and/or titanium nitride (TiN).

10. The semiconductor device of claim 8 , wherein the contact hole has a width of greater than a width of the groove.

11. The semiconductor device of claim 8 , wherein the groove of the lower metal line has a depth of about 500 Å-1,500 Å.

12. The semiconductor device of claim 11 , wherein:

the groove of the lower metal line has a depth of about 500 Å-1,500 Å.

13. A method, comprising:

partially etching a metal layer on a semiconductor substrate to form a plurality of grooves or indentations in an upper surface of the metal layer at a plurality of first locations, the grooves or indentations having a first width;

fully etching the metal layer at a plurality of second locations so as to form a plurality of lower metal lines having a second width, the second width being greater than the first width, and the second locations not coinciding with the first locations;

forming an insulator layer over the lower metal line; and

etching the insulator layer to form a plurality of contact holes exposing the indentation or at least part of the groove and a top surface of the metal line.

14. The method of claim 13 , further comprising forming a contact electrode filling the contact hole.

15. The method of claim 14 , further comprising forming an upper metal line electrically connected to the contact electrode contact electrode.