Sidewall image transfer process

• US 8,883,649 B2
• Filed: 03/23/2011
• Issued: 11/11/2014
• Est. Priority Date: 03/23/2011
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Yin, Yunpeng, Arnold, John C., Colburn, Matthew E., Burns, Sean D.
• Primary Examiner(s): Lee, Jae
• Assistant Examiner(s): JEFFERSON, QUOVAUNDA
• Application Number:
  US13/069,536
• Publication Number:
  US 20120244711A1
• Time in Patent Office: 1,329 Days
• Field of Search: 438/694, 438/706, 438/717, 438/736, 438/942, 438/FOR.473
• US Class Current: 438/706
• CPC Class Codes: H01L 21/0337 characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment
• CPC Class Codes: H01L 21/3086 characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment
• CPC Class Codes: H01L 21/31144 using masks
• CPC Class Codes: H01L 21/32139 using masks

Abstract

An improved method of performing sidewall spacer imager transfer is presented. The method includes forming a set of sidewall spacers next to a plurality of mandrels, the set of sidewall spacers being directly on top of a hard-mask layer; transferring image of at least a portion of the set of sidewall spacers to the hard-mask layer to form a device pattern; and transferring the device pattern from the hard-mask layer to a substrate underneath the hard-mask layer.

Claims

1. A method comprising:

forming a set of sidewall spacers next to a plurality of mandrels, said set of sidewall spacers being directly on top of a second hard-mask layer;

forming a photo-resist block mask, said photo-resist block mask exposing at least a portion of said set of sidewall spacers and covering rest of said set of sidewall spacers;

transferring image of said at least a portion of said set of sidewall spacers to said second hard-mask layer to form a device pattern; and

transferring said device pattern from said second hard-mask layer to a substrate underneath said second hard-mask layer, including transferring said device pattern to a first hard-mask layer, said first hard-mask layer being underneath said second hard-mask layer and separated from thereof by a planarization layer, said planarization layer being an amorphous carbon layer.

2. The method of claim 1, wherein forming said set of sidewall spacers comprises:

creating said plurality of mandrels from a planarization layer, said planarization layer being directly on top of said hard-mask layer;

depositing a conformal layer of dielectric material suitable for said sidewall spacers covering said plurality of mandrels; and

performing directional etching of said conformal layer to create said set of sidewall spacers.

3. The method of claim 2, wherein creating said plurality of mandrels comprises:

depositing an anti-reflective coating layer on top of said planarization layer;

forming a photo-resist pattern of said plurality of mandrels lithographically on top of said anti-reflective coating layer;

transferring said photo-resist pattern into said planarization layer through directional etching of said planarization layer utilizing said hard-mask layer underneath thereof as an etch-stop layer.

4. The method of claim 1, further comprising removing said sidewall spacers remaining on top of said device pattern of said second hard-mask layer and the rest of said second hard-mask layer through a burn-off process.

5. The method of claim 4, wherein said burn-off process comprises subjecting said sidewall spacers to a plasma environment, wherein said plasma environment comprises fluorocarbon gas of CF4 or C4F8, hydrogenated fluorocarbon gas CHxFy, and diluting gas of Ar or nitrogen.

6. The method of claim 1, wherein said first and second hard-mask layers are titanium-nitride layers and wherein said planarization layer is of a material that is able to withstand a process of depositing said second titanium-nitride layer on top thereof without causing decomposition.

7. The method of claim 1, wherein said second hard-mask layer has a thickness that is equal or less than that of said first hard-mask layer, and wherein said planarization layer has a thickness ranging from about 10 nm to about 100 nm.

8. A method of performing sidewall spacer image transfer, said method comprising:

forming a set of sidewall spacers next to a set of mandrels respectively, said set of sidewall spacers being directly on top of a second hard-mask layer;

transferring image of at least a portion of said set of sidewall spacers to said second hard-mask layer to form a device pattern; and

transferring said device pattern from said second hard-mask layer to a first hard-mask layer and subsequently to a substrate underneath said first hard-mask layer,

wherein said first and second hard-mask layers are titanium-nitride layers separated by a planarization layer, said planarization layer is of a material that is able to withstand a process of depositing said second titanium-nitride layer on top thereof without causing decomposition.

9. The method of claim 8, wherein forming said set of sidewall spacers comprises:

creating said set of mandrels from a planarization layer, said planarization layer being directly on top of said second hard-mask layer;

depositing a conformal layer of dielectric material covering said set of mandrels, said dielectric material being suitable for said sidewall spacers; and

performing directional etching to remove said conformal layer thereby leaving only said set of sidewall spacers at sidewalls of said set of mandrels.

10. The method of claim 9, wherein creating said set of mandrels comprises:

depositing an anti-reflective coating layer on top of said planarization layer;

exposing lithographically a photo-resist layer on top of said anti-reflective coating layer to form a photo-resist pattern of said set of mandrels;

transferring said photo-resist pattern into said planarization layer through directional etching of said planarization layer utilizing said second hard-mask layer as an etch-stop layer.

11. The method of claim 8, further comprising forming a photo-resist mask to cover rest of said set of sidewall spacers except said at least a portion of said set of sidewall spacers, before image of said at least a portion of said set of sidewall spacers is transferred to said second hard-mask layer.

12. The method of claim 11, further comprising removing said sidewall spacers remaining on top of said device pattern of said second hard-mask layer and the rest of said second hard-mask layer through a burn-off process, said burn-off process comprises subjecting said sidewall spacers to a plasma environment, wherein said plasma environment comprises fluorocarbon gas of CF4 or C4F8, hydrogenated fluorocarbon gas CHxFy, and diluting gas of Ar or nitrogen.

13. The method of claim 8, wherein said planarization layer between said first and said second hard-mask layer is an amorphous carbon layer.

14. The method of claim 8, wherein said second hard-mask layer has a thickness that is equal or less than that of said first hard-mask layer, and wherein said planarization layer has a thickness ranging from about 10 nm to about 100 nm.

15. A method of transferring sidewall spacer image comprising:

forming a set of sidewall spacers next to sidewalls of a corresponding set of mandrels, said set of sidewall spacers being directly on top of a second hard-mask layer;

transferring image of a portion of said set of sidewall spacers to said second hard-mask layer to form a device pattern;

transferring said device pattern from said second hard-mask layer to a first hard-mask layer; and

transferring said device pattern from said first hard-mask layer subsequently to a substrate underneath said first hard-mask layer,

wherein said first and second hard-mask layers are titanium-nitride layers separated by a planarization layer, said planarization layer is of a material that is able to withstand a process of depositing said second titanium-nitride layer on top thereof without causing decomposition.

16. The method of claim 15, wherein forming said set of sidewall spacers comprises:

depositing a planarization layer on top of said second hard-mask layer;

etching said planarization layer to form thereby said set of mandrels;

depositing a conformal layer of dielectric material covering said set of mandrels, said dielectric material being suitable for said sidewall spacers; and

performing directional etching to remove said conformal layer thereby leaving only said set of sidewall spacers at sidewalls of said set of mandrels.

17. The method of claim 16, wherein forming said set of mandrels comprises:

depositing an anti-reflective coating layer on top of said planarization layer;

exposing lithographically a photo-resist layer on top of said anti-reflective coating layer to form a photo-resist pattern of said set of mandrels;

transferring said photo-resist pattern into said planarization layer through a directional etching process utilizing said second hard-mask layer as an etch-stop layer.

18. The method of claim 15, further comprising, before image of said at least a portion of said set of sidewall spacers being transferred to said second hard-mask layer, forming a photo-resist mask that covers rest of said set of sidewall spacers except said at least a portion of said set of sidewall spacers.

19. The method of claim 18, further comprising removing said sidewall spacers remaining on top of said device pattern of said second hard-mask layer and the rest of said second hard-mask layer through a burn-off process, said burn-off process comprises subjecting said sidewall spacers to a plasma environment, wherein said plasma environment comprises fluorocarbon gas of CF4 or C4F8, hydrogenated fluorocarbon gas CHxFy, and diluting gas of Ar or nitrogen.

20. The method of claim 15, wherein said planarization layer between said first and said second hard-mask layer is an amorphous carbon layer.

21. The method of claim 15, wherein said second hard-mask layer has a thickness that is equal or less than that of said first hard-mask layer, and wherein said planarization layer has a thickness ranging from about 10 nm to about 100 nm.