Method to improve electrical leakage performance and to minimize electromigration in semiconductor devices

1. A method of forming a doped layer, the method comprising:

planarizing a top surface of a workpiece to form a substantially planar surface with a plurality of copper conductive paths and a plurality of dielectric regions;

infusing a dopant material into and below the planarized top surface of the workpiece using a gas cluster ion beam (GCIB) to form a doped layer from the top surface to a desired depth of about 50-200 angstroms beneath the top surface in the plurality of copper conductive paths and the plurality of dielectric regions, wherein the dopant material comprises one or more dopant elements selected from the group consisting of B, C, Si, Ge, N, P, As, O, S, and Cl, and wherein said doped layer comprises between 0.1 atomic % and 10 atomic % of the dopant material; and

forming a diffusion barrier layer over the doped layer as a barrier to diffusing copper atoms, wherein the doped layer minimize electromigration of copper in the conductive paths.

2. The method of claim 1 , wherein the material source comprises phosphine and a non-condensable source gas selected from the group consisting of helium, neon, and hydrogen.

3. The method of claim 2 , further including a second condensable gas source selected from the group consisting of argon, nitrogen, carbon dioxide, and oxygen.

4. The method of claim 1 , wherein the GCIB comprises SiH 4 , Si 2 H 6 , SiH 2 Cl 2 , SiCl 3 H, methylsilane, dimethylsilane, trimethylsilane, tetramethylsilane, ethylsilane, diethylsilane, triethylsilane, tetraethylsilane, SiCl 4 , SiF 4 , GeH 4 , Ge 2 H 6 , GeH 2 Cl 2 , GeCl 3 H, methylgermane, dimethylgermane, trimethylgermane, tetramethylgermane, ethylgermane, diethylgermane, triethylgermane, tetraethylgermane, GeCl 4 , GeF 4 , N 2 , H 2 , O 2 , NO, NO 2 , N 2 O, NH 3 , NF 3 , HCl, SF 6 , CO, CO 2 , C 2 H 4 , CH 4 , C 2 H 2 , C 2 H 6 , C 3 H 4 C 3 H 6 , C 3 H 8 , C 4 H 6 , C 4 H 8 , C 4 H 10 , C 5 H 8 , C 5 H 10 , C 6 H 6 , C 6 H 10 , C 6 H 12 , BF 3 , B 2 H 6 , AsH 3 , AsF 5 , PH 3 , PF 3 , PCl 3 , or PF 5 , or any combination of two or more thereof.

5. The method of claim 1 , further including a pre-treatment step prior to infusing the dopant material into the planarized top surface of the workpiece.

6. The method of claim 1 , wherein the substantially planar surface is planarized by a chemical mechanical planarization or an electropolishing process.

7. The method of claim 1 , wherein the diffusion barrier layer is selected from the group consisting of silicon nitride, silicon carbide, nitrogen doped silicon nitride, boron carbon nitride, and boron nitride.

8. A method of minimizing electromigration in copper conductive paths, the method comprising:

forming one or more copper conductive paths on a workpiece; and

infusing a phosphorus dopant into and below the top surface of the workpiece using a gas cluster ion beam to form a phosphorus-doped layer from the top surface to a desired depth of about 50-200 angstroms beneath the top surface in the one or more copper conductive paths wherein the presence of the phosphorus dopant is effective to minimize electromigration in the one or more copper conductive paths, and wherein said phosphorus-doped layer comprises between 0.1 atomic % and 10 atomic % of the phosphorus dopant.

9. The method of claim 8 , wherein the gas cluster ion beam comprises PH 3 , PF 3 , PCl 3 , or PF 5 , or any combination of two or more thereof, and a non-condensable source gas selected from the group consisting of helium, neon, and hydrogen.

10. The method of claim 8 , further including pre-treating the top surface of the workpiece prior to infusing the phosphorus dopant.