Method of depositing a copper seed layer which promotes improved feature surface coverage

• US 6,391,776 B1
• Filed: 01/05/2001
• Issued: 05/21/2002
• Est. Priority Date: 01/08/1999
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Zhang, Hong-Mei, Hashim, Imran, Forster, John C.
• Primary Examiner(s): Nelms, David
• Assistant Examiner(s): Nhu, David
• Application Number:
  US09/754,894
• Time in Patent Office: 501 Days
• Field of Search: 438/687, 438/624, 438/629, 438/637, 438/639, 438/685, 438/672, 438/666, 438/766, 438/758, 438/584
• US Class Current: 438/687
• 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 21/76877 Filling of holes, grooves or trenches, e.g. vias, with conductive material
• CPC Class Codes: H01L 23/53233 Copper alloys
• CPC Class Codes: H01L 23/53238 Additional layers associated with copper layers, e.g. adhesion, barrier, cladding layers
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A method of improving step coverage of a copper seed layer deposited over a semiconductor feature surface which is particularly useful for small size features having a high aspect ratio. Using a contact via as an example of a high aspect ratio feature, we have demonstrated that it is possible to increase the copper seed layer coverage simultaneously at both the bottom of the via and on the wall of the via . This increase is achieved by increasing the percentage of the depositing copper species which are ions. The percentage of species ionization which is necessary to obtain sufficient step coverage for the copper seed layer is a function of the aspect ratio of the feature. For features having a 0.25 μm or smaller feature size, an aspect ratio of about 3:1 requires that about 50% or more of the copper species be ions at the time of deposition on the substrate.

Claims

1. A method of providing a copper seed layer over an interior surface of a feature upon or within a semiconductor substrate, said method comprising:

depositing said copper seed layer over said interior surface of said feature using copper species wherein at least 30 percent of said species are in the form of copper ions at the time said species contact said substrate surface, so that a continuous copper seed layer is formed.

2. The method of claim 1, wherein said percent of species which are copper ions ranges between about 50% and about 100%.

3. The method of claim 2, wherein said percent of species which are copper ions ranges between about 50% and about 90%.

4. The method of claim 3, wherein said percent of species which are copper ions ranges between about 60% and about 90%.

5. The method of claim 1, or claim 2, or claim 3, or claim 4, wherein said percentage of copper species which are ions is obtained by ion deposition sputtering, wherein power is applied to an ionizing device located between a source of said copper species and said semiconductor substrate, and wherein the ambient pressure surrounding the copper species at the time of application of the ionization energy provided by said RF power source is at least 30 mTorr.

6. The method of claim 5, wherein said ambient pressure is at least 40 mTorr.

7. The method of claim 6, wherein said ambient pressure is at least 60 mTorr.

8. An apparatus used to provide a continuous copper seed layer over an interior surface of a feature upon or within a semiconductor substrate, according to the method of claim 1, said apparatus including an electronic device which is programmed to carry out steps of said method.

9. The apparatus of claim 8, wherein said apparatus also includes an ionizing device located between a source used to generate copper species and said semiconductor substrate.

10. The apparatus of claim 9, wherein RF power is applied to said ionizing device.

19. The method of claim 1, wherein said feature has a feature size of 0.25 μ

m or less and an aspect ratio of about 3;

1 or greater, and wherein said percent of species which are copper ions ranges is at least about 50%.

20. The method of claim 19, wherein said feature has an aspect ratio of about 4:

1 or greater, and wherein said percent of species which are copper ions ranges is at least about 60%.

21. The method of claim 20, wherein said feature has an aspect ratio of about 5:

1 or greater, and wherein said percent of species which are copper ions ranges is at least about 80%.

11. A method of providing a complete copper fill of a semiconductor feature upon or within a semiconductor substrate, said method comprising:

depositing a continuous copper seed layer over an interior surface of said feature using copper species wherein at least 30 percent of said species are in the form of copper ions at the time said species contact said substrate surface; and

subsequently depositing a copper fill layer over said continuous copper seed layer.

12. The method of claim 11, wherein said percent of said copper species which are ions ranges between about 30% and about 90%.

13. The method of claim 12, wherein said percent of said copper species which are ions ranges between about 50% and about 90%.

14. The method of claim 13, wherein said percent of said copper species which are ions ranges between about 70% and about 90%.

15. The method of claim 11, or claim 12, or claim 13, or claim 14, wherein said percentage of copper species which are ions is obtained by ion deposition sputtering, wherein power is applied to an ionizing device located between a source of said copper species and said semiconductor substrate, and wherein the ambient pressure surrounding the copper species at the time of application of the ionization energy provided by said RF power source is at least 30 mTorr.

16. An apparatus used to provide a complete copper fill of a semiconductor feature, according to the method of claim 11, said apparatus including an electronic device which is programmed to carry out steps of said method.

17. The apparatus of claim 16, wherein said apparatus also includes an ionizing device located between a source used to generate copper species and said semiconductor substrate.

18. The apparatus of claim 17, wherein RF power is applied to said ionizing device.

22. The method of claim 11, wherein said feature has a feature size of 0.25 μ

m or less and an aspect ratio of about 3;

1 or greater, and wherein said percent of species which are copper ions ranges is at least about 50%.

23. The method of claim 22, wherein said feature has an aspect ratio of about 4:

1 or greater, and wherein said percent of species which are copper ions ranges is at least about 60%.

24. The method of claim 23, wherein said feature has an aspect ratio of about 5:

1 or greater, and wherein said percent of species which are copper ions ranges is at least about 80%.