Methods for planarizing a metal layer
View Patent ↗Methods for planarizing a metal layer in a semiconductor device are disclosed. An illustrated example method comprises dividing a metal layer into a first section and a second section. A polishing removal rate associated with the first section is greater than a polishing removal rate associated with the second section. The method also includes forming an oxide layer on the first section of the metal layer; and planarizing the oxide layer and the metal layer using a chemical mechanical polishing process.
1. A method for planarizing a metal layer comprising:
forming the metal layer on a wafer having a first section and a second section, wherein a polishing removal rate associated with the first section is greater than a polishing removal rate associated with the second section;
forming a first oxide layer on the first section of the metal layer, wherein a surface of the second section remains substantially free of oxide or has a second oxide layer thereon that is thinner than the first oxide layer; and
chemical mechanical polishing the first oxide layer and the metal layer to remove the first oxide layer and planarize the metal layer.
2. A method as defined in claim 1 , wherein the first section comprises a center area of the wafer.
3. A method as defined in claim 1 , wherein the metal layer comprises a copper layer.
4. A method as defined in claim 1 , wherein the first section comprises an outer edge of the wafer.
5. A method as defined in claim 4 , wherein the metal layer comprises a copper layer.
6. A method as defined in claim 1 , further comprising a third section between to first and second sections.
7. A method as defined in claim 6 , further comprising forming a third layer onto third section.
8. A method as defined in claim 7 , wherein the first oxide layer is thicker than the third oxide layer.
9. A method as defined in claim 8 , wherein the metal layer comprises a copper layer.
10. A method as defined in claim 6 , further comprising forming the second oxide layer on the second section.
11. A method as defined in claim 10 , wherein the second oxide layer is thicker than any third oxide layer in the third section.
12. A method as defined in claim 11 , wherein the metal layer comprises a copper layer.
13. A method as defined in claim 6 , wherein the first, second and third sections are concentric.
14. A method as defined in claim 1 further comprising:
forming an interlayer dielectric layer on a wafer; and
forming the metal layer by depositing conductive material on the interlayer dielectric layer.
15. A method as defined in claim 14 further comprising forming a via hole in the interlayer dielectric layer.
16. A method as defined in claim 14 , wherein the chemical mechanical polishing process results in the metal layer being coplanar with the interlayer dielectric layer.
17. A method for planarizing a metal layer comprising:
forming an oxide layer on a first section of a metal layer without forming an oxide layer on a second a section of the metal layer, wherein a polishing removal rate associated with the first section is greater than a polishing removal rate associated with the second section; and
removing the oxide layer and planarizing the metal layer using a chemical mechanical polishing process.
18. A method for planarizing a metal layer comprising:
forming a first oxide layer on a first section of a metal layer;
forming a second oxide layer on a second section of the metal layer, wherein the first oxide layer is thicker than the second oxide layer, and a polishing removal rate associated with the first section is greater than a polishing removal rate associated with the second section; and
removing to first and second oxide layers and planarizing the metal layer using a chemical mechanical polishing process.
19. A method as defined in claim 18 , wherein the first oxide layer has a thickness of 1200˜1600 Å.
20. A method as defined in claim 18 , wherein the second oxide layer has a thickness of 200˜600 Å.