Granted Patent B2

US 7,422,979 · App. 11/078,236 · Granted Sep 9, 2008

Abstract

Claims (34)

1. A method of forming a semiconductor device, the method comprising steps of:

providing a semiconductor substrate;

forming a conductor over the semiconductor substrate, wherein the conductor comprises copper;

forming a diffusion barrier stack over the conductor, wherein forming the diffusion barrier stack comprises:

forming a layer comprising a metal over the conductor, wherein the layer comprises a first element, a second element, and a third element, wherein:

the first element is cobalt (Co) or nickel (Ni)

the second element is tungsten (W), rhenium (Re) or molybdenum (Mo), and

the third element is boron (B) or phosphorous (P);

forming a first dielectric layer substantially devoid of oxygen over the layer, wherein forming the first dielectric layer further comprises forming a first dielectric layer having a thickness less than 20 nanometers, wherein the first dielectric layer has dielectric constant that is less than the dielectric constant of stoichiometric silicon nitride, and wherein:

when forming the first dielectric layer, the layer comprising the metal has a substantially uniform thickness between the conductor and the first dielectric layer; and

the first dielectric layer is of a thickness that alone it can not serve as a diffusion barrier layer to the conductor; and

forming a second dielectric layer over the diffusion barrier stack, wherein the second dielectric layer includes silicon carbide nitride (SiCN).

2. The method of claim 1 , wherein forming the layer, further comprises selectively depositing the layer.

3. The method of claim 1 , wherein the first dielectric layer comprises an element selected from the group consisting of silicon, nitrogen and carbon.

4. The method of claim 1 , further comprising removing at least a portion of the diffusion barrier stack.

5. A method of forming a semiconductor device, the method comprising steps of:

providing a semiconductor substrate;

forming a first dielectric layer over the semiconductor substrate, wherein forming the first dielectric layer further comprises forming a first dielectric layer having a thickness less than 20 nanometers, and wherein the first dielectric layer has dielectric constant that is less than the dielectric constant of stoichiometric silicon nitride;

patterning the first dielectric layer to form a first opening having a sidewall;

forming a conductor material in the first opening, wherein the conductor comprises copper;

polishing the conductor material to form a conductor, wherein an uppermost point of the side of the conductor lies at substantially the same elevation as an uppermost point of the conductor;

forming an electromigration reduction layer over the conductor, wherein the

electromigration reduction layer includes a first element, a second element, and a third element, wherein:

the first element is cobalt (Co) or nickel (Ni);

the second element is tungsten (W), rhenium (Re) or molybdenum (Mo), and

the third element is boron (B) or phosphorous (P); and

forming a second dielectric layer over the electromigration reduction layer and the first dielectric layer, wherein the second dielectric layer includes silicon carbide nitride (SiCN).

6. The method of claim 5 , further comprising

removing a portion of the second dielectric layer to form a second opening; and

forming a via over the conductor in the second opening.

7. The method of claim 6 , further comprising removing a portion of the electromigration reduction layer.

8. The method of claim 5 , wherein forming the electromigration reduction layer, further comprises selectively depositing the layer.

9. The method of claim 5 , further comprising forming a second dielectric layer over the diffusion barrier stack.

10. The method of claim 5 , wherein the first dielectric layer comprises an element selected from the group consisting of silicon, nitrogen and carbon.

Assignments (15)