VLSI fabrication processes for introducing pores into dielectric materials

• US 7,166,531 B1
• Filed: 01/31/2005
• Issued: 01/23/2007
• Est. Priority Date: 01/31/2005
• Status: Expired due to Fees

• Current Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Original Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Inventors: Humayun, Raashina, Hill, Richard S., Sun, Jianing, Draeger, Nerissa S., Ray, Gary William, van den Hoek, Willibrordus Gerardus Maria
• Primary Examiner(s): Lebentritt; Michael
• Assistant Examiner(s): Ullah; Elias
• Application Number:
  US11/050,621
• Time in Patent Office: 722 Days
• Field of Search: 438/780, 438/692, 438/618
• US Class Current: 438/623
• CPC Class Codes: H01L 21/02126 the material containing Si, O, and at least one of H, N, C, F, or other non-metal elements, e.g. SiOC, SiOC:H or SiONC
• CPC Class Codes: H01L 21/02203 the layer being porous
• CPC Class Codes: H01L 21/0234 treatment by exposure to a plasma
• CPC Class Codes: H01L 21/02343 treatment by exposure to a liquid
• CPC Class Codes: H01L 21/02348 treatment by exposure to UV light
• CPC Class Codes: H01L 21/02351 treatment by exposure to corpuscular radiation, e.g. exposure to electrons, alpha-particles, protons or ions
• CPC Class Codes: H01L 21/02362 formation of intermediate layers, e.g. capping layers or diffusion barriers
• CPC Class Codes: H01L 21/31695 Deposition of porous oxides or porous glassy oxides or oxide based porous glass
• CPC Class Codes: H01L 21/76807 for dual damascene structures
• CPC Class Codes: H01L 21/7682 the dielectric comprising air gaps
• CPC Class Codes: H01L 2221/1047 the air gaps being formed by pores in the dielectric
• CPC Class Codes: Y10S 438/96 Porous semiconductor

Abstract

Porous dielectric layers are produced by introducing pores in pre-formed composite dielectric layers. The pores may be produced after the barrier material, the metal or other conductive material is deposited to form a metallization layer. In this manner, the conductive material is provided with a relatively smooth continuous surface on which to deposit.

Claims

1. A method of forming a layer comprising conductive lines on a substrate, the method comprising:

(a) providing a layer of composite dielectric material on the substrate, wherein the composite dielectric material comprises a dielectric network and a porogen;

(b) treating the dielectric network in a manner that shrinks and/or strengthens the layer of dielectric material;

(c) patterning the layer of composite dielectric material to define paths for the conductive lines;

(d) filling the paths with conductive material; and

(e) after filling the paths in (d), removing at least some of the porogen from the layer of composite dielectric material to produce a porous dielectric network.

2. The method of claim 1, further comprising removing excess conductive material formed in (d) prior to removing the porogen in (e), to thereby form an exposed pattern of conductive lines in the composite dielectric material.

3. The method of claim 2, wherein removing the excess conductive material also serves to produce a planarized surface.

4. The method of claim 1, wherein treating the dielectric network serves to strengthen the dielectric network.

5. The method of claim 1, wherein treating the dielectric network comprises exposing the dielectric network to at least one of the following:

ultraviolet radiation, e-beam radiation, and a plasma.

6. The method of claim 1, wherein the dielectric network comprises a material selected from the group consisting of silicon oxide, a carbon doped silicon oxide, a fluorinated silicate glass, silicon nitride, a spin-on organic material, a spin-on inorganic material, and a spin-on inorganic-hybrid material.

7. The method of claim 1, wherein the dielectric network comprises an extended three-dimensional covalently bonded network.

8. The method of claim 1, wherein the dielectric network comprises a three-dimensional cross-linked structure.

9. The method of claim 1, wherein the conductive material is copper.

10. The method of claim 1, wherein filling the paths with a conductive material comprises plating the conductive material.

11. The method of claim 1, wherein removing at least some of the porogen from the layer of composite dielectric material comprises exposing the composite dielectric material to at least one of the following:

a supercritical solvent, a plasma, a thermal treatment, ultraviolet radiation, and e-beam radiation.

12. The method of claim 1, wherein (c) is performed prior to (b).

13. A method of forming a layer comprising conductive lines on a substrate, the method comprising:

(a) forming a layer of porous dielectric material on the substrate, wherein the porous dielectric material comprises voids;

(b) filling at least some voids in the dielectric material with a sealant;

(c) patterning the layer of composite dielectric material to define paths for the conductive lines;

(d) filling the paths with conductive material; and

(e) after filling the paths in (d), removing at least some of the sealant from the dielectric material.

14. The method of claim 13, further comprising removing excess conductive material formed in (d) prior to removing the porogen in (e), to thereby form an exposed pattern of conductive lines in the composite dielectric material.

15. The method of claim 14, wherein removing the excess conductive material also serves to produce a planarized surface.

16. The method of claim 13, wherein the sealant is a photoresist material, benzocyclobutene, or a BARC compound.

17. The method of claim 13, wherein filling at least some voids comprises ALD, spin-on, CVD, in situ polymerization, liquid impregnation, vapor impregnation, or supercritical injection.

18. The method of claim 13, wherein the conductive material is copper.

19. The method of claim 13, wherein filling the paths with a conductive material comprises plating the conductive material.

20. The method of claim 13, wherein removing at least some of the sealant from the dielectric material comprises exposing the dielectric material to at least one of the following:

a supercritical solvent, a plasma, a thermal treatment, ultraviolet radiation, and e-beam radiation.

21. The method of claim 13, wherein the dielectric material comprises a three-dimensional cross-linked structure.

22. The method of claim 13, wherein the dielectric material is selected from the group consisting of silicon oxide, a carbon doped silicon oxide, a fluorinated silicate glass, silicon nitride, a spin-on organic material, a spin-on inorganic material, and a spin-on inorganic-hybrid material.

23. The method of claim 13, wherein (b) is performed prior to (c).

24. The method of claim 13, wherein (c) is performed prior to (b).

25. A method of forming a layer comprising conductive lines on a substrate, the method comprising:

(a) directly depositing a dielectric layer comprising a dielectric network on the substrate, without curing or polymerizing the as deposited dielectric material;

(b) treating the dielectric network in a manner that shrinks and/or strengthens the layer of dielectric material;

(c) patterning the dielectric layer to define paths for the conductive lines;

(d) filling the paths with conductive material; and

(e) after filling the paths in (d), removing porogen from the dielectric layer to produce a porous dielectric network.

26. The method of claim 25, whererin the porogen is deposited together with the dielectric network in the dielectric layer.

27. The method of claim 25, wherein the porogen is added to the dielectric layer after (a) but before (c).

28. The method of claim 25, further comprising removing excess conductive material formed in (d) prior to removing porogen in (e), to thereby form an exposed pattern of conductive lines in the dielectric layer.

29. The method of claim 28, wherein removing the excess conductive material also serves to produce a planarized surface.

30. The method of claim 25, wherein the dielectric network comprises a material selected from the group consisting of silicon oxide, a carbon doped silicon oxide, a fluorinated silicate glass, silicon nitride, a spin-on organic material, a spin-on inorganic material, and a spin-on inorganic-hybrid material.

31. The method of claim 25, wherein the dielectric network comprises an extended three-dimensional covalently bonded network.

32. The method of claim 25, wherein the dielectric network comprises a three-dimensional cross-linked structure.

33. The method of claim 25, wherein the conductive material is copper.

34. The method of claim 25, wherein filling the paths with a conductive material comprises plating the conductive material.

35. The method of claim 25, wherein removing at least some of the porogen from the layer of composite dielectric material comprises exposing the composite dielectric material to at least one of the following:

a supercritical solvent, a plasma, a thermal treatment, ultraviolet radiation, and e-beam radiation.

36. The method of claim 25, wherein treating the dielectric network comprises exposing the dielectric network to at least one of the following:

ultraviolet radiation, e-beam radiation, and a plasma.