Atomic layer profiling of diffusion barrier and metal seed layers

• US 7,842,605 B1
• Filed: 05/24/2007
• Issued: 11/30/2010
• Est. Priority Date: 04/11/2003
• Status: Active Grant

• Current Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Original Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Inventors: Pradhan, Anshu A., Rozbicki, Robert
• Primary Examiner(s): Coleman; W. David
• Assistant Examiner(s): KING, SUN MI KIM
• Application Number:
  US11/807,179
• Time in Patent Office: 1,286 Days
• Field of Search: 438/627, 438/628, 257/E21.582
• US Class Current: 438/627
• CPC Class Codes: C23C 14/046 Coating cavities or hollow spaces, e.g. interior of tubes; Infiltration of porous substrates
• CPC Class Codes: C23C 14/345 using substrate bias
• 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 21/76805 the opening being a via or contact hole penetrating the underlying conductor
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• CPC Class Codes: H01L 21/76865 Selective removal of parts of the layer H01L21/76844 takes precedence

Abstract

Material is removed from a substrate surface (e.g., from a bottom portion of a recessed feature on a partially fabricated semiconductor substrate) by subjecting the surface to a plurality of profiling cycles, wherein each profiling cycle includes a net etching operation and a net depositing operation. An etching operation removes a greater amount of material than is being deposited by a depositing operation, thereby resulting in a net material etch-back per profiling cycle. About 2-10 profiling cycles are performed. The profiling cycles are used for removing metal-containing materials, such as diffusion barrier materials, copper line materials, and metal seed materials by PVD deposition and resputter. Profiling with a plurality of cycles removes metal-containing materials without causing microtrenching in an exposed dielectric. Further, overhang is reduced at the openings of the recessed features and sidewall material coverage is improved. Integrated circuit devices having higher reliability are fabricated.

Claims

1. A method of processing a layer of material on a semiconductor substrate having a recessed feature, the method comprising:

(a) depositing a layer of a first diffusion barrier material on the semiconductor substrate, to coat at least a bottom portion of the recessed feature; and

(b) performing a plurality of profiling cycles, wherein each profiling cycle comprises a net etching operation removing a first portion of a material residing at the bottom of the recessed feature and a net deposition operation depositing a second portion of the first diffusion barrier material at the bottom of the recessed feature, the removed portion of the material being greater than the deposited portion of the material for at least one of the profiling cycles, and wherein performing the plurality of profiling cycles achieves net material etching at the bottom portion of the recessed feature;

(c) depositing a layer of second diffusion barrier material on the semiconductor substrate, to coat at least the bottom portion of the recessed feature; and

(d) performing a plurality of profiling cycles, wherein each profiling cycle comprises a net etch-back operation and a net deposition operation, wherein the net deposition operation comprises depositing the second diffusion barrier material.

2. The method of claim 1, wherein (b) comprises performing 2-10 profiling cycles.

3. The method of claim 1, wherein (b) comprises performing 4-6 profiling cycles.

4. The method of claim 1, wherein (b) comprises performing 2 profiling cycles.

5. The method of claim 1, wherein (b) comprises alternating net etch and net deposition operations.

6. The method of claim 1, wherein a first profiling cycle in (b) comprises the net etch operation performed before the net deposition operation.

7. The method of claim 1, wherein a first profiling cycle in (b) comprises the net deposition operation performed before the net etch operation.

8. The method of claim 1, wherein (b) comprises removing less than about 300 Å

of material from the bottom of the recessed feature per one net etching operation.

9. The method of claim 1, wherein (b) comprises removing about 100-200 Å

of material from the bottom of the recessed feature per one net etching operation.

10. The method of claim 1, wherein (b) comprises removing between about 5 to 50 Å

of material from the bottom of the recessed feature per one net etching operation.

11. The method of claim 1, wherein (b) comprises depositing less than about 100 Å

of material in the bottom of the recessed feature per one net depositing operation.

12. The method of claim 1, wherein (b) comprises depositing between about 5 to 20 Å

of material in the bottom of the recessed feature per one net depositing operation.

13. The method of claim 1, wherein (b) comprises etching between about 5 to 100 Å

of material from the bottom of the recessed feature per one profiling cycle.

14. The method of claim 1, wherein (b) comprises etching between about 10 to 50 Å

of material from the bottom of the recessed feature per one profiling cycle.

15. The method of claim 1, wherein (b) comprises removing between about 5 to 80 Å

of material from a field region of the semiconductor substrate per one net etching operation and depositing between about 5-50 Å

of material onto the field region of the semiconductor substrate per one net depositing operation.

16. The method of claim 1, wherein (b) comprises performing at least some net etching operations using resputter.

17. The method of claim 1, wherein (b) comprises performing at least some net etching operations using resputter having an etch rate to deposition rate ratio (E/D) of at least about 2 at the bottom of the recess.

18. The method of claim 1, wherein (b) comprises performing at least some net etching operations using resputter having an etch rate to deposition rate ratio (E/D) of at least about 1.1 in a field region of the semiconductor substrate.

19. The method of claim 1, wherein (a) and (b) are performed in one processing chamber.

20. The method of claim 1, wherein (a) and (b) are performed in a plasma physical vapor deposition (PVD) process chamber.

21. The method of claim 1, wherein (a) and (b) are performed in a process chamber comprising a hollow cathode magnetron.

22. The method of claim 1, wherein (a) and (b) are performed in a process chamber comprising a planar magnetron.

23. The method of claim 1, wherein (a) comprises depositing the diffusion barrier layer by a method selected from the group consisting of chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD) and pulsed deposition layer (PDL).

24. The method of claim 1, wherein (a) comprises depositing the diffusion barrier material to between about 20 and 120 Å

on a field region of the semiconductor substrate.

25. The method of claim 1, wherein the recessed feature is a via, and wherein (b) comprises removing a portion of a layer of metal underlying said via to form an anchor recess.

26. The method of claim 1, wherein (b) comprises exposing a layer of dielectric in a higher-lying recessed feature, while removing material from the bottom portion of a lower lying recessed feature.

27. The method of claim 1, wherein (b) comprises removing material from the bottom portion of the recess without substantially damaging an exposed layer of a dielectric on the semiconductor substrate.

28. The method of claim 1, wherein (b) comprises removing between about 10-600 Å

of material from the bottom portion of the recessed feature without substantially damaging an exposed layer of a dielectric on the semiconductor substrate.

29. The method of claim 1, wherein the semiconductor substrate comprises a via and a trench, said trench having a layer of exposed dielectric during at least one of the net etching operations;

and wherein (b) comprises removing material from a bottom portion of the via without forming microtrenches in the exposed layer of the dielectric residing at the bottom of the trench.

30. The method of claim 27, wherein the exposed dielectric layer comprises a low-k or an ultra low-k dielectric.

31. The method of claim 27, wherein the exposed dielectric layer comprises a porous dielectric.

32. The method of claim 1, wherein the net deposition operation in (b) comprises depositing a first diffusion barrier material selected from the group consisting of Ta, TaN_x, Ti, TiN_X, W, WN_x, Ru, and Co.

33. The method of claim 1, wherein the net deposition operation in (b) comprises depositing Ta and/or TaN_x.

34. The method of claim 1, wherein the first diffusion barrier material comprises TaN, and the second diffusion barrier material comprises Ta.

35. The method of claim 1, further comprising depositing a flash layer of diffusion barrier material after (b) to coat at least the bottom portion of the recessed feature.

36. The method of claim 1, wherein (b) provides a diffusion barrier coverage of at least about 5 Å

at bottom corners of the recessed feature.

37. The method of claim 1, wherein (b) reduces a diffusion barrier overhang located at an opening of the recessed feature.