SiARC REMOVAL WITH PLASMA ETCH AND FLUORINATED WET CHEMICAL SOLUTION COMBINATION

• US 20160372334A1
• Filed: 06/18/2015
• Published: 12/22/2016
• Est. Priority Date: 06/18/2015
• Status: Active Grant

• Current Assignee: Globalfoundries US Incorporated (GlobalFoundries, Inc.), International Business Machines Corporation, STMicroelectronics Incorporated (STMicroelectronics NV)
• Original Assignee: GlobalFoundries, Inc., International Business Machines Corporation, STMicroelectronics Incorporated (STMicroelectronics NV)
• Inventors: Mignot, Yann, Peethala, Brown C., Siddiqui, Shariq
• Granted Patent: US 9,508,560 B1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01L 21/0276 using an anti-reflective coating anti-reflective coating for lithography in general G03F7/09
• CPC Class Codes: H01L 21/0332 characterised by their composition, e.g. multilayer masks, materials
• 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 21/31111 by chemical means
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31144 using masks
• CPC Class Codes: H01L 21/3115 Doping the insulating layers
• 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

Abstract

A method that allows effective removal of a silicon-containing antireflective coating (SiARC) layer in a block mask after defining an unblock area in a sidewall image transfer (SIT) patterning process without causing a height loss of the SIT spacers is provided. The method includes first modifying the SiARC layer with a dry etch utilizing an etching gas comprising a nitrogen gas followed by treating the modified SiARC layer with a wet chemical etch utilizing an aqueous solution including dilute hydrofluoric acid and citric acid.

Claims

1. A method of forming a semiconductor structure comprising:

forming a plurality of sidewall image transfer (SIT) spacers over a metal nitride hard mask layer located over at least one underlying material layer;

forming a patterned stack that comprises a patterned silicon-containing antireflective coating (SiARC) layer overlying a patterned organic planarization layer (OPL) over the SIT spacers and the metal nitride hard mask layer, the patterned stack exposing at least one portion of the plurality of SIT spacers;

exposing the patterned SiARC layer to an etching gas comprising a nitrogen gas to modify the patterned SiARC layer; and

treating the modified patterned SiARC layer with an aqueous solution comprising dilute hydrofluoric acid to remove the modified patterned SiARC layer from a top surface of the patterned OPL, wherein the dilute hydrofluoric acid comprises a part of hydrofluoric acid and 50 to 10000 parts of deionized water.

2. The method of claim 1, wherein the etching gas further comprises a hydrogen gas.

3. The method of claim 1, wherein the etching gas is fluorine free and does not include a fluorocarbon gas.

5. The method of claim 1, wherein the aqueous solution further comprises citric acid.

6. The method of claim 1, wherein the plurality of SIT spacers comprises a low temperature dielectric oxide.

7. The method of claim 1, wherein the metal nitride hard mask layer comprises TiN, TiON, TaN, WN, BN, a combination thereof, or a stack thereof.

8. The method of claim 1, wherein the patterned OPL comprises spin-on carbon (SOC), diamond-like carbon, polyarylene ether, or polyimide.

9. The method of claim 1, wherein the etching gas does not etch the SIT spacers.

10. The method of claim 9, wherein the aqueous solution removes the patterned SiARC layer selective to the SIT spacers, the patterned OPL, and the metal nitride hard mask layer.

11. The method of claim 1, wherein the forming the patterned stack comprises:

forming an OPL over the SIT spacers and the metal nitride hard mask layer;

forming a SiARC layer over the OPL;

forming a patterned photoresist layer over the SiARC layer, the patterned photoresist layer having at least one opening therein;

transferring the pattern of the at least one opening into the SiARC layer and the OPL layer to provide the patterned SiARC layer and the patterned OPL layer; and

removing the patterned photoresist layer from the patterned OPL layer.

12. The method of claim 1, wherein the forming the plurality of SIT spacers comprises:

forming a mandrel material layer over the metal nitride hard mask layer;

patterning the mandrel material layer to provide a plurality of mandrel structures;

conformally depositing a spacer material layer over the plurality of mandrel structures and metal nitride hard mask layer;

removing horizontal portions of the spacer material layer by an anisotropic etch; and

removing the plurality of mandrel structures.

13. The method of claim 12, wherein the patterning the mandrel material layer comprises:

forming another OPL over the mandrel material layer;

forming another SiARC layer over the OPL;

forming another photoresist layer over the another OPL;

patterning the another photoresist layer;

transferring a pattern in the patterned another photoresist layer into the another SiARC layer and the another OPL; and

patterning the mandrel material layer employing remaining portions of the another SiARC layer and the another OPL as an etch mask.

14. The method of claim 13, further comprising:

forming a mandrel cap layer over the mandrel material layer prior to the patterning the mandrel material layer, wherein the another OPL is formed over the mandrel cap layer, and the method further comprises patterning the mandrel cap layer employing the remaining portions of the another SiARC layer and the another OPL as an etch mask to provide a mandrel cap atop each of the plurality of mandrel structures.

15. The method of claim 1, further comprising etching the metal nitride hard mask layer employing the patterned OPL as an etch mask to provide a patterned metal nitride hard mask layer.

16. The method of claim 15, further comprising removing the patterned OPL from the patterned metal nitride hard mask layer.

17. The method of claim 16, wherein the at least one underlying material layer comprises a dielectric hard mask layer located underneath the metal nitride hard mask layer, and a dielectric material layer located underneath the dielectric hard mask layer, and a dielectric cap layer located underneath the dielectric material layer.

18. The method of claim 17, wherein the at least one underlying material layer is located over a substrate, and the method further comprises etching the dielectric hard mask layer and the dielectric material layer using the patterned metal nitride hard mask layer as an etch mask.

19. A method of forming a semiconductor structure comprising:

forming a plurality of sidewall image transfer (SIT) spacers over a metal nitride hard mask layer, wherein the metal nitride hard mask layer is located over a dielectric hard mask layer overlying at least one underlying material layer;

forming a patterned stack that comprises a patterned silicon-containing antireflective coating (SiARC) layer overlying a patterned organic planarization layer (OPL) over the SIT spacers and the metal nitride hard mask layer, the patterned stack exposing at least one portion of the plurality of SIT spacers;

patterning the metal nitride hard mask layer employing the exposed portion of the plurality of SIT spacers as an etch mask;

exposing the patterned SiARC layer to an etching gas comprising a nitrogen gas to modify the patterned SiARC layer, wherein the etching gas does not etch the SIT spacers and the dielectric hard mask layer; and

treating the modified patterned SiARC layer with an aqueous solution comprising dilute hydrofluoric acid to remove the modified patterned SiARC layer from a top surface of the patterned OPL.

4. The method of claim 19, wherein the dilute hydrofluoric acid comprises a part of hydrofluoric acid and 50 to 10000 parts of deionized water.

20. (canceled)

21. A method of forming a semiconductor structure comprising:

forming a plurality of sidewall image transfer (SIT) spacers over a metal nitride hard mask layer located over at least one underlying material layer;

forming a patterned stack that comprises a patterned silicon-containing antireflective coating (SiARC) layer overlying a patterned organic planarization layer (OPL) over the SIT spacers and the metal nitride hard mask layer, the patterned stack exposing at least one portion of the plurality of SIT spacers;

exposing the patterned SiARC layer to an etching gas comprising a nitrogen gas to modify the patterned SiARC layer, wherein the etching gas does not etch the SIT spacers; and

treating the modified patterned SiARC layer with an aqueous solution comprising dilute hydrofluoric acid to remove the modified patterned SiARC layer from a top surface of the patterned OPL.