Integrated circuit contact system

1. A method for forming an integrated circuit contact system, the method comprising:

forming a contact plug in a dielectric;

forming a first barrier layer in a trench in the dielectric and on the contact plug;

digging out or resputtering a portion of the first barrier layer situated at a bottom of the trench and depositing the material on a portion of the first barrier layer situated on a sidewall of the trench, thereby causing the portion of the first barrier layer situated at the bottom of the trench to have a reduced, non-zero thickness; and

forming a second barrier layer over the first barrier layer and filling a corner area of the trench, wherein the corner area of the trench is situated below a top surface of the contact plug.

2. The method of claim 1 further comprising forming a wide interconnect trench to partially overlap the contact plug.

3. The method of claim 1 further comprising forming an offset interconnect layer to overlap the contact plug.

4. The method of claim 1 further comprising forming a narrow interconnect layer to completely overlap the contact plug.

5. The method of claim 1 further comprising:

forming an interconnect layer of high diffusion metal on the second barrier layer in the trench; and

forming the second barrier layer of a material to prevent diffusion.

6. A method for forming an integrated circuit contact system, the method comprising:

forming a contact plug in a dielectric;

sputtering a first barrier layer in a trench in the dielectric and on the contact plug using a high power sputtering process;

resputtering the first barrier layer to remove a portion of barrier material from a bottom of the trench and to deposit the barrier material on the sidewall of the trench using a high power sputtering process, thereby causing the first barrier layer to have a reduced, non-zero thickness at the bottom of the trench; and

sputtering a second barrier over the first barrier layer, the second barrier layer is substantially applied to the first barrier material on the bottom of the trench and minimally applied to the first barrier layer on the sidewall of the trench, and the second barrier layer fills a corner area of the trench using a high power sputtering process, wherein the corner area of the trench is situated below a top surface of the contact plug.

7. The method of claim 6 further comprising forming a wide interconnect trench, wherein the wide interconnect trench substantially overlaps the contact plug and has two corner areas.

8. The method of claim 6 further comprising forming an offset interconnect layer, wherein the offset interconnect layer partially overlaps the contact plug and has a single corner area.

9. The method of claim 6 further comprising forming a narrow interconnect layer, wherein the narrow interconnect layer partially overlaps the contact plug and has corner areas.

10. The method of claim 6 further comprising:

forming an interconnect layer of copper on the second barrier layer in the trench; and

sputtering the first and second barrier layer using tantalum.