Method of forming air gaps in a dielectric material using a sacrificial film
View Patent ↗A method of forming air gaps surrounding conductors in a dielectric layer, the dielectric layer comprising, for example, part of the interconnect structure of an integrated circuit device. The air gaps are formed, in part, by depositing a sacrificial material within a trench and/or via that have been formed in a dielectric layer, and the sacrificial material is ultimately removed after metal deposition to create the air gaps. A porous dielectric cap may be deposited over the dielectric layer, and the sacrificial material may be removed through this porous dielectric layer. Other embodiments are described and claimed.
1. A method comprising:
forming a trench and a via in a layer of dielectric material, the via having one end opening into the trench and an opposing end extending down to a conductor in an underlying layer;
selectively depositing a layer of a sacrificial material over the dielectric material layer and over surfaces of the trench and via;
depositing a layer of a conductive material over the sacrificial material layer and the conductor in the underlying layer;
removing excess conductive material and excess sacrificial material from an upper surface of the dielectric material layer;
depositing a layer of a porous dielectric material over the upper surface of the dielectric material layer and exposed portions of the conductive and sacrificial material layers; and
removing the sacrificial material to form air gaps surrounding the conductive material within the trench and the via.
2. The method of claim 1 , wherein the sacrificial material layer comprises a polymer material.
3. The method of claim 2 , wherein the sacrificial material layer is deposited using a chemical growth process.
4. The method of claim 2 , wherein the sacrificial material layer is deposited using a photo induced-free radical polymerization process.
5. The method of claim 1 , wherein the conductive material comprises copper.
6. The method of claim 1 , wherein the excess conductive and sacrificial materials are removed from the upper surface of the dielectric material layer using a chemical-mechanical polishing (CMP) process.
7. The method of claim 1 , wherein the porous dielectric material comprises a silica based material, a silicon nitride based material, a silicon carbide based material, an amorphous carbon based material, or an organic film.
8. The method of claim 1 , wherein removing the sacrificial material comprises:
thermally decomposing the sacrificial material layer into one or more residue materials; and
performing a rinse process to remove the residue materials through the porous dielectric layer.
9. The method of claim 8 , wherein thermal decomposition is performed at a temperature up to approximately 450° C.
10. The method of claim 8 , wherein the rinse process is performed using a supercritical CO 2 agent.
11. The method of claim 1 , wherein the air gaps each have a thickness of between 5 nm and 15 nm.
12. The method of claim 1 , wherein the underlying layer comprises another layer of dielectric material.
13. The method of claim 1 , wherein the underlying layer comprises a semiconductor wafer.
14. A method comprising:
forming a trench and a via in a layer of dielectric material, the via having one end opening into the trench and an opposing end extending down to a conductor in an underlying layer;
depositing a layer of a sacrificial material over the dielectric material layer and over surfaces of the trench and via;
etching the sacrificial material layer to remove at least a portion of the sacrificial material layer overlying the conductor in the underlying layer;
depositing a layer of a conductive material over the sacrificial material layer and the conductor in the underlying layer;
removing excess conductive material and excess sacrificial material from an upper surface of the dielectric material layer;
depositing a layer of a porous dielectric material over the upper surface of the dielectric material layer and exposed portions of the conductive and sacrificial material layers; and
removing the sacrificial material to form air gaps surrounding the conductive material within the trench and the via.
15. The method of claim 14 , wherein the sacrificial material layer comprises a polymer material.
16. The method of claim 14 , wherein the conductive material comprises copper.
17. The method of claim 14 , wherein the porous dielectric material comprises a silica based material, a silicon nitride based material, a silicon carbide based material, an amorphous carbon based material, or an organic film.
18. The method of claim 14 , wherein removing the sacrificial material comprises:
thermally decomposing the sacrificial material layer into one or more residue materials; and
performing a rinse process to remove the residue materials through the porous dielectric layer.
19. The method of claim 14 , etching the sacrificial material layer to remove at least a portion of the sacrificial material layer overlying the conductor in the underlying layer comprises performing an anisotropic etch process.