Triple damascence tungsten-copper interconnect structure

• US 6,258,707 B1
• Filed: 01/07/1999
• Issued: 07/10/2001
• Est. Priority Date: 01/07/1999
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Uzoh, Cyprian E.
• Primary Examiner(s): Meier, Stephen D.
• Assistant Examiner(s): GUERRERO, MARIA F
• Application Number:
  US09/227,010
• Time in Patent Office: 915 Days
• Field of Search: 438/653, 438/654, 438/656, 438/618, 438/622, 438/627-629, 438/643, 438/644, 438/648, 438/688, 438/685, 438/675, 438/640, 438/665, 257/760
• US Class Current: 438/618
• CPC Class Codes: H01L 21/31144 using masks
• CPC Class Codes: H01L 21/3212 by chemical mechanical polishing [CMP]
• CPC Class Codes: H01L 21/76808 involving intermediate temporary filling with material
• CPC Class Codes: H01L 21/76813 involving a partial via etch
• CPC Class Codes: H01L 21/76816 Aspects relating to the layout of the pattern or to the size of vias or trenches layout of the interconnections per se H01L23/528; CAD of ICs G06F30/00
• CPC Class Codes: H01L 21/76831 in via holes or trenches, e.g. non-conductive sidewall liners
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• CPC Class Codes: H01L 21/76846 Layer combinations
• CPC Class Codes: H01L 21/76847 the layer being positioned within the main fill metal
• CPC Class Codes: H01L 21/76849 the layer being positioned on top of the main fill metal
• CPC Class Codes: H01L 21/76877 Filling of holes, grooves or trenches, e.g. vias, with conductive material
• CPC Class Codes: H01L 23/5226 Via connections in a multilevel interconnection structure
• 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 structure and process for a triple damascene interconnection device. The device is formed within a terraced trench formed using damascene techniques within a single, relatively thick dielectric film. The interconnection device formed within the terraced structure includes a plurality of films and is a vertically coherent, redundant structure.

Claims

1. A process for forming a connection device, comprising the steps of:

(a) forming a contact layer over a substrate, said contact layer having a contact surface;

(b) forming a dielectric film over said contact surface, said dielectric film having a top, a bottom, and an upper surface;

(c) forming a terraced trench opening within said dielectric film, said terraced trench opening having a trench bottom surface and at least three adjoining vertical sections, each vertical section having at least one generally vertical side wall and being connected to an adjoining vertical section by a substantially horizontal lip, the vertical sections becoming progressively wider from bottom to top of the dielectric film;

(d) forming a barrier film at least within said terraced trench opening;

(e) depositing a tungsten liner film at least over said barrier film;

(f) forming a spacer film over said tungsten liner film, said spacer film comprising one of titanium nitride and hexagonal tantalum nitride;

(g) forming a copper seed layer over said spacer film;

(h) filling said terraced trench opening with a conductive film comprising electrodepositing; and

(i) polishing said device thereby forming a polished surface over said terraced trench opening, said polished surface being substantially parallel to said upper surface of said dielectric film.

2. The process as in claim 1, in which said step (c) includes exposing a portion of said contact surface through said trench bottom surface of said terraced trench opening, wherein said trench bottom surface comprises said portion of said contact surface.

3. The process as in claim 1, wherein said step (e) of depositing comprises chemical vapor deposition.

4. The process as in claim 1, wherein said terraced trench opening has an average aspect ratio of 4.2 or greater.

5. The process as in claim 1, wherein said step (d) comprises depositing at least one film selected from the group of films consisting of Si₃N₄, SiO₂, Al₂O₃, Ti, Ta, TaW, TiN, and hexagonal TaN.

6. The process as in claim 1, wherein said step (d) comprises the steps of forming a Pd film using electroless deposition processes, then forming a CoP film over said Pd film using electroless deposition processes.

7. The process as in claim 1, in which said step (d) includes forming a continuous barrier film covering said upper surface, said side walls, said lips, and said trench bottom surface.

8. The process as in claim 1, further comprising including a nitrogen source toward the end of said step (e) of depositing.

9. The process as in claim 1, wherein said barrier film is discontinuous toward said trench bottom surface of said terraced trench opening, and wherein said step (e) of depositing a tungsten liner film includes forming said tungsten liner film over portions of said side walls, said lips, and said trench bottom surface not covered by said barrier film.

10. The process as in claim 1, in which step (e) includes forming a spacer film over said tungsten liner film, said spacer film comprising one of titanium nitride and hexagonal tantalum nitride.

11. The process as in claim 1, wherein said conductive film is copper.

12. The process as in claim 1, wherein said conductive film is an aluminum film.

13. The process as in claim 1, wherein said step (g) of polishing comprises chemical mechanical polishing.

14. The process as in claim 1, wherein said step (c) comprises sequentially etching a plurality of openings within said dielectric film, each opening having an associated width and a common center point, wherein the width of each sequentially etched opening is greater than the width of the previously etched opening.

15. The process as in claim 1, wherein said contact layer is an electrically conductive material.

16. The process as in claim 1, in which said step (b) includes forming a capping film on said upper surface of said dielectric film, said capping film having a capping surface and wherein said polished surface is substantially continuous with said capping surface.

17. The process as in claim 16, wherein said capping film comprises one of Al₂O₃ and silicon nitride.

18. A process for forming a connection device, comprising the steps of:

(a) forming a contact layer over a substrate, said contact layer having a contact surface;

(b) forming a dielectric film having a top, a bottom, and an upper surface over said contact surface;

(c) forming a terraced trench opening within said dielectric film, said terraced trench opening having a trench bottom surface and at least two adjoining vertical sections, each vertical section having a generally vertical side wall and being connected to an adjoining vertical section by a substantially horizontal lip, the vertical sections becoming progressively wider from bottom to top;

(d) forming a barrier film at least within said terraced trench opening;

(e) depositing a bulk conductive film over said barrier film, said bulk conductive film partially filling said terraced trench opening;

(f) filling said terraced trench opening with a film including tungsten;

(g) polishing to produce a polished surface substantially continuous with said upper surface, said polished surface comprising a central portion comprised of said tungsten and at least one further section comprised of said bulk conductive film.

19. The process as in claim 18, wherein said bulk conductive film is aluminum.

20. The process as in claim 18, wherein said bulk conductive film is one of gold and nickel.

21. The process as in claim 18, further comprising the step (h) of selectively depositing one of a cobalt tungsten film, a cobalt phosphorus film, and a cobalt tungsten phosphorus film over said polished surface.

22. The process as in claim 18, wherein said contact layer is an electrically conductive material.

23. The process as in claim 18, in which said step (c) includes exposing a portion of said contact surface through said trench bottom surface of said terraced trench opening, wherein said trench bottom surface comprises said portion of said contact surface.

24. The process as in claim 18, further comprising the step (d1) of forming a copper seed layer film over said barrier film and wherein said step (e) comprises electrodepositing.

25. The process as in claim 18, further comprising the step (e1) of forming a spacer film over said bulk conductive film.

26. The process as in claim 23, wherein said step (c) comprises the steps of:

(c1) creating a first pattern in a first photosensitive film, said first pattern including a first opening having a first width, said first opening exposing a first portion of said dielectric film;

(c2) etching said first portion of said dielectric film to a first depth thereby forming a trench opening within said dielectric film, said trench opening including a landing and upper side walls;

(c3) removing said first photosensitive film;

(c4) forming a collar film on said upper surface and covering said landing and said upper side walls;

(c5) creating a second pattern in a second photosensitive film, said second pattern including a second opening having a second width less than said first width, said second opening exposing a first area of said collar film disposed on said landing;

(c6) etching through said first area of said collar film and etching said dielectric film to a second depth greater than said first depth, thereby forming said trench bottom surface; and

(c7) removing said second photosensitive film;

wherein said trench opening comprises said terraced trench opening.

27. The process as in claim 24, wherein said bulk conductive film is copper.

28. The process as in claim 26, wherein the collar film includes at least one of an insulating film and a conductive film.

29. The process as in claim 26, wherein said collar film comprises a film selected from the group of films consisting of SiN, SiO₂, Al₂O₃, Ti, Ta, TiW, and TaW.

30. The process as in claim 25, wherein said spacer film comprises a nitride of one of tungsten, titanium, and tantalum.

31. A process for forming a connection device, comprising the steps of:

(a) forming a contact layer over a substrate, said contact layer having a contact surface;

(b) forming a dielectric film over said contact surface, said dielectric film having a top, a bottom, and an upper surface;

(c) forming a terraced trench opening within said dielectric film, said terraced trench opening having a trench bottom surface and at least three adjoining vertical sections, each vertical section having at least one generally vertical side wall and being connected to an adjoining vertical section by a substantially horizontal lip, the vertical sections becoming progressively wider from bottom to top of the dielectric film, said step of forming a terraced trench comprising the steps of;

(c1) creating a first pattern in a first photosensitive film, said first pattern including a first opening with a first width, said first opening exposing a first portion of said dielectric film;

(c2) etching said first portion of said dielectric film to a first depth thereby forming a trench opening within said dielectric film, said trench opening including a landing and upper side walls;

(c3) removing said first photosensitive film;

(c4) forming a collar film on said upper surface and covering said landing and said upper side walls;

(c5) creating a second pattern in a second photosensitive film, said second pattern including a second opening with a second width less than said first width, said second opening exposing a first area of said collar film disposed on said landing;

(c6) etching through said first area of said collar film and etching said dielectric film to a second depth greater than said first depth, thereby enlarging said trench opening and forming a bottom surface within said dielectric film;

(c7) removing said second photosensitive film;

(c8) creating a third pattern in a third photosensitive film, said third pattern including a third opening with a third width greater than said second width but less than said first width, said third opening exposing said bottom surface of said dielectric film and a second area of said collar film disposed on said landing;

(c9) etching through said second area of said collar film and etching said dielectric film to a third depth greater than said second depth thereby exposing a portion of said contact surface through said trench bottom surface of said terraced trench; and

(c10) removing said third photosensitive film;

wherein said first opening, said second opening, and said third opening have a common center point and said trench opening comprises said terraced trench opening;

(d) forming a barrier film at least within said terraced trench opening;

(e) depositing a tungsten liner film at least over said barrier film;

(f) filling said terraced trench opening with a conductive film; and

(g) polishing said device thereby forming a polished surface over said terraced trench opening, said polished surface being substantially parallel to said upper surface of said dielectric film.

32. The process as in claim 31, wherein said step (c4) comprises depositing at least one film selected from the group of films consisting of Si₃N₄, SiO₂, Al₂O₃, Ti, Ta, TaW, TiN, and TaN.

33. A process for forming a connection device, comprising the steps of:

(a) forming a contact layer over a substrate, said contact layer having a contact surface;

(b) forming a dielectric film over said contact surface, said dielectric film having a top, a bottom, and an upper surface;

(c) forming a terraced trench opening within said dielectric film, said terraced trench opening having a trench bottom surface and at least three adjoining vertical sections, each vertical section having at least one generally vertical side wall and being connected to an adjoining vertical section by a substantially horizontal lip, the vertical sections becoming progressively wider from bottom to top of the dielectric film;

(d) forming a barrier film at least within said terraced trench opening comprising depositing at least one film selected from the group of films consisting of Si₃N₄, SiO₂, Al₂O₃, Ti, Ta, TaW, TiN, and hexagonal TaN.;

(e) depositing a tungsten liner film at least over said barrier film;

(f) filling said terraced trench opening with a conductive film; and

(g) polishing said device thereby forming a polished surface over said terraced trench opening, said polished surface being substantially parallel to said upper surface of said dielectric film.

34. A process for forming a connection device, comprising the steps of:

(a) forming a contact layer over a substrate, said contact layer having a contact surface;

(b) forming a dielectric film over said contact surface, said dielectric film having a top, a bottom, and an upper surface;

(c) forming a terraced trench opening within said dielectric film, said terraced trench opening having a trench bottom surface and at least three adjoining vertical sections, each vertical section having at least one generally vertical side wall and being connected to an adjoining vertical section by a substantially horizontal lip, the vertical sections becoming progressively wider from bottom to top of the dielectric film;

(d) forming a barrier film at least within said terraced trench opening;

(e) depositing a tungsten liner film at least over said barrier film and forming a spacer film over said tungsten liner film, said spacer film comprising one of titanium nitride and hexagonal tantalum nitride;

(f) filling said terraced trench opening with a conductive film; and

(g) polishing said device thereby forming a polished surface over said terraced trench opening, said polished surface being substantially parallel to said upper surface of said dielectric film.