Methods and apparatus for forming barrier layers in high aspect ratio vias

1. An integrated system adapted to form a barrier layer on sidewalls and a bottom of a via that extends through a dielectric layer to expose an underlying metal feature of a substrate, the integrated system comprising:

an atomic layer deposition (ALD) chamber adapted to deposit a conformal barrier layer over the sidewalls and bottom of the via;

a high density plasma physical vapor deposition (HDPPVD) chamber adapted to deposit a seed layer on the sidewalls and bottom of the via;

a transfer chamber coupled to the ALD chamber and adapted to transfer the substrate between the ALD chamber and the HDPPVD chamber under vacuum; and

at least one controller coupled to the ALD chamber, the transfer chamber and the HDPPVD chamber and adapted to perform the steps of:

(a) forming a barrier layer over the sidewalls and bottom of the via using atomic layer deposition within the ALD chamber, the barrier layer having sufficient thickness to serve as a diffusion barrier to at least one of atoms of the metal feature and atoms of a seed layer formed over the barrier layer;

(b) transferring the substrate from the ALD chamber to the HDPPVD chamber;

(c) removing at least a portion of the barrier layer from the bottom of the via by sputter etching the substrate within the HDPPVD chamber using a plasma ion density of at least 10 10 ions/cm 3 , wherein a bias is applied to the substrate during at least a portion of the sputter etching; and

(d) depositing a seed layer on the sidewalls and bottom of the via within the HDPPVD chamber.

2. The integrated system of claim 1 wherein the barrier layer comprises tantalum nitride.

3. The integrated system of claim 2 wherein the barrier layer has a thickness of between about 50 to 60 angstroms.

4. The integrated system of claim 1 wherein steps (c) and (d) occur sequentially.

5. The integrated system of claim 1 wherein at least a portion of steps (c) and (d) occur simultaneously.

6. An integrated system adapted to form a barrier layer on sidewalls and a bottom of a via that extends through a dielectric layer to expose an underlying metal feature of a substrate, the integrated system comprising:

an atomic layer deposition (ALD) chamber adapted to deposit a conformal barrier layer over the sidewalls and bottom of the via;

a high density plasma physical vapor deposition (HDPPVD) chamber adapted to deposit a seed layer on the sidewalls and bottom of the via;

a transfer chamber coupled to the ALD chamber and adapted to transfer the substrate between the ALD chamber and the HDPPVD chamber under vacuum; and

at least one controller coupled to the ALD chamber, the transfer chamber and the HDPPVD chamber and adapted to perform the steps of:

(a) employing the ALD chamber to deposit a conformal Ta-containing barrier layer on the sidewalls and bottom of the via, the barrier layer having sufficient thickness to serve as a diffusion barrier to copper atoms;

(b) transferring the substrate through the transfer chamber to a substrate support pedestal of the HDPPVD chamber;

(c) removing at least a portion of the barrier layer deposited on the bottom of the via by:

maintaining a noble-gas containing sub-atmospheric environment of less than about 100 millitorr within the HDPPVD chamber;

generating a plasma having an ion density of at least 10 10 ions/cm 3 within the HDPPVD chamber; and

applying power to the substrate support pedestal so as to attract at least noble-gas ions to the substrate and resputter at least a portion of the barrier layer from the bottom of the via; and

(d) depositing a copper seed layer on the sidewalls and bottom of the via by:

maintaining a noble-gas containing sub-atmospheric environment of less than about 100 millitorr within the HDPPVD chamber;

generating a plasma having an ion density of at least 10 10 ions/cm 3 within the HDPPVD chamber;

applying power to a copper target of the HDPPVD chamber so as to sputter copper atoms from the target;

ionizing at least a portion of the sputtered copper atoms; and

applying power to the substrate support pedestal so as to attract at least ionized copper atoms to the substrate, thereby forming a copper seed layer on the bottom and sidewalls of the via.

7. The integrated system of claim 6 wherein steps (c) and (d) are performed sequentially.

8. The integrated system of claim 6 wherein at least a portion of steps (c) and (d) are performed simultaneously.

9. The integrated system of claim 6 wherein at least one of steps (c) and (d) comprises applying power to a coil disposed between the copper target and the substrate support pedestal to increase an ionization density of the plasma.

10. The integrated system of claim 1 wherein the controller is adapted to perform step (c) using a plasma having a plasma ion density of at least 10 11 ions/cm 3 in a bulk region of the plasma.

11. The integrated system of claim 10 wherein the controller is adapted to perform step (c) using a plasma having a plasma ion density of at least 10 12 ions/cm 3 in a bulk region of the plasma.

12. The integrated system of claim 6 wherein the controller is configured such that the plasma ion density during step (d) reaches at least 10 11 ions/cm 3 in a bulk region of the plasma.

13. The integrated system of claim 12 wherein the controller is configured such that the plasma ion density during step (d) reaches at least 10 12 ions/cm 3 in a bulk region of the plasma.

14. The integrated system of claim 6 wherein the controller is configured such that the plasma ion density during step (e) includes a metal ion density of at least 10 10 metal ions/cm 3 in a bulk region of the plasma.

15. The integrated system of claim 14 wherein the controller is configured such that the plasma ion density during step (e) includes a metal ion density of at least 10 11 metal ions/cm 3 in a bulk region of the plasma.