Deposition of thin continuous PVD seed layers having improved adhesion to the barrier layer

• US 7,645,696 B1
• Filed: 06/22/2006
• Issued: 01/12/2010
• Est. Priority Date: 06/22/2006
• Status: Active Grant

• Current Assignee: Novellus Systems Incorporated (LAM Research Corporation)
• Original Assignee: Novellus Systems Incorporated (LAM Research Corporation)
• Inventors: Yu, Tom, Juliano, Daniel R., Vijayendran, Anil, Dulkin, Alexander
• Primary Examiner(s): LEBENTRITT, MICHAEL
• Application Number:
  US11/473,618
• Time in Patent Office: 1,300 Days
• Field of Search: 438/629, 438/622, 438/636, 438/722, 438/734, 438637-695, 438/760, 438/765, 438/772, 438/774, 438/776, 257/E21.576, 257/579, 257/E21.169, 257/171, 257/175, 257582-585, 257/592
• US Class Current: 438/637
• CPC Class Codes: C23C 14/022 by means of bombardment with energetic particles or radiation
• CPC Class Codes: C23C 14/046 Coating cavities or hollow spaces, e.g. interior of tubes; Infiltration of porous substrates
• CPC Class Codes: H01L 21/02068 during, before or after processing of conductive layers, e.g. polysilicon or amorphous silicon layers
• CPC Class Codes: H01L 21/2855 by physical means, e.g. sputtering, evaporation H01L21/28518 - H01L21/28537 and H01L21/28568 take precedence
• CPC Class Codes: H01L 21/32131 by physical means only
• CPC Class Codes: H01L 21/76813 involving a partial via etch
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• CPC Class Codes: H01L 21/76862 Bombardment with particles, e.g. treatment in noble gas plasmas; UV irradiation
• CPC Class Codes: H01L 21/76865 Selective removal of parts of the layer H01L21/76844 takes precedence
• CPC Class Codes: H01L 21/76873 for electroplating

Abstract

Methods of depositing thin seed layers that improve continuity of the seed layer as well as adhesion to the barrier layer are provided. According to various embodiments, the methods involve performing an etchback operation in the seed deposition chamber prior to depositing the seed layer. The etch step removes barrier layer overhang and/or oxide that has formed on the barrier layer. It some embodiments, a small deposition flux of seed atoms accompanies the sputter etch flux of argon ions, embedding metal atoms into the barrier layer. The embedded metal atoms create nucleation sites for subsequent seed layer deposition, thereby promoting continuous seed layer film growth, film stability and improved seed layer-barrier layer adhesion.

Claims

1. A method of depositing a metal conductive seed layer on a substrate comprising:

a) providing a substrate having a barrier layer in a recessed feature deposited thereon to a seed layer deposition chamber;

b) performing an inert gas sputter etch of at least the sidewalls of the barrier layer in the seed layer deposition chamber;

c) depositing the metal conductive seed layer over the surface of the wafer substrate in the seed layer deposition chamber.

2. The method of claim 1 wherein the sputter etch removes barrier material that overhangs the recessed feature on the substrate.

3. The method of claim 1 wherein the seed layer is a copper seed layer.

4. The method of claim 1 wherein the barrier layer comprises tantalum.

5. The method of claim 1 further comprising simultaneously sputtering metal atoms from a target while performing the sputter etch of the barrier material.

6. The method of claim 5 wherein the metal atoms become embedded within the barrier layer during the sputtering process.

7. The method of claim 6 wherein the embedded metal atoms are nucleation sites for the seed layer deposition in (c).

8. The method of claim 1 wherein (b) comprises sputtering a metal from target having an applied DC power of between about 0 and 10 kW while applying a RF bias to the wafer substrate.

9. The method of claim 1 wherein (b) comprises applying a RF bias of at least about 100 W to the substrate.

10. The method of claim 1 wherein the seed layer deposition chamber comprises a HCM.

11. The method of claim 1 wherein the seed layer deposition chamber comprises a planar magnetron.

12. The method of claim 1 wherein further comprising, prior to (a), depositing the barrier layer on the substrate.

13. The method of claim 1 further comprising electroplating metal on the seed layer.

14. The method of claim 1 wherein the barrier layer provided in (a) has oxide formed thereon and wherein at least some of said oxide is removed during (b).

24. The method of claim 1 wherein the seed layer deposition chamber comprises a wafer support to support a wafer and a metal seed target located in proximity to the wafer support such that when sputtered from the target, metal seed material is deposited on a wafer supported by the wafer support.

15. A method of depositing a metal seed layer on a semiconductor substrate having recessed features;

the method comprising;

a) providing the substrate with a barrier layer in a recessed feature deposited thereon to the seed layer deposition chamber;

b) applying a DC power to a metal target within the chamber and an applied RF bias to the substrate to simultaneously etch at least the sidewalls of the barrier layer oxide and implant metal atoms into the barrier layer;

c) applying a DC power to the metal target to deposit a metal seed layer that substantially coats the sidewalls of the features, wherein the implanted seeds are nucleation sites for the deposition of the metal seed layer.

16. The method of claim 15 wherein (b) further comprises sputtering excess barrier material from the tops of the features.

17. The method of claim 15 wherein the substrate undergoes a vacuum break between deposition of the barrier layer and deposition of the seed layer.

18. The method of claim 15 wherein the DC power applied in (b) is between about 0 and 5 W/cm2.

19. The method of claim 15 wherein the RF power applied in (b) is between about 0.1 and 5 W/cm2.

20. The method of claim 15 further comprising, prior to (a), depositing the barrier layer by a sputtering process.

21. The method of claim 20 wherein therein the substrate undergoes a vacuum break between deposition of the barrier layer and providing the substrate to the deposition chamber.

22. The method of claim 20 wherein therein the substrate does not undergo a vacuum break between deposition of the barrier layer and providing the substrate to the deposition chamber.

23. The method of claim 15 wherein the pressure during b) ranges from 1e−

3 to 1e−

2 Torr and the pressure during c) ranges from 5e−

5 to 5e−

3 Torr.