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# c12) United States Patent 

# Ouattara et al. 

# (54) ASSIST LAYERS FOR EUV LITHOGRAPHY 

(71) Applicant: Brewer Science Inc., Rolla, MO (US) 

(72) Inventors: Tantiboro Ouattara, Eureka, MO (US); Carlton Washburn, Rolla, MO (US); Vandana Krishnamurthy, Rolla, MO (US); Douglas Guerrero, Rolla, MO (US); Aline Collin, Fairbanks, AK (US) 

(73) Assignee: Brewer Science Inc., Rolla, MO (US) 

( *) Notice: Subject to any disclaimer, the term ofthis patent is extended or adjusted under 35 U.S.C. 154(b) by 33 days. This patent is subject to a terminal dis› claimer. 

(21) Appl. No.: 13/682,050 

(22) Filed: Nov. 20, 2012 

## (65) Prior Publication Data 

US 2013/0129995 Al May 23, 2013 

(60) Provisional application No. 61/562,166, filed on Nov. 21, 2011. 

(51) Int. Cl. 

<img src='content_image/911446.jpg'>

(52) U.S. Cl. CPC .............. G03F 71092 (2013.01); G03F 712004 (2013.01); G03F 7111 (2013.01); B82Y 30/00 (2013.01); YJ0S 977/755 (2013.01); B82Y 40/00 (2013.01) USPC ............................ 430/323; 430/322; 977/755 

( 58) Field of Classification Search CPC ............. G03F 7/092; G03F 7/11; G03F 7/20; G03F 7/2004 USPC .................................................. 430/322, 323 See application file for complete search history. 

## Related U.S. Application Data 

<img src='content_image/911462.jpg'>

# (IO) Patent No.: US 8,968,989 B2 

# (45) Date of Patent: *Mar. 3, 2015 

## (56) References Cited 

<img src='content_image/911447.jpg'>

## FOREIGN PATENT DOCUMENTS 

JP 2002-198283 7/2002 

Goldberg et al., "An EUV Fresnel zoneplate mask-imaging micro› scope for lithography generations reaching 8 nm," Proc. of SPIE, 2011, vol. 7969, 796910-1-796910-12. 

Roberts et al., "Sensitivity ofEUV resists to out-of-band radiation," Proc. ofSPIE, 2009, vol. 7273, 72731W-l-72731W-13. 

Xu et al., "Underlayer designs to enhance the performance ofEUV resists," Proc. ofSPIE, 2009, vol. 7273, 72731J-l-72731J-ll. 

International Search Report and Written Opinion dated Mar. 4, 2013 in corresponding PCT/US2012/066074 filed Nov. 20, 2012. 

Thackeray et al., "EUV Resists based on Low Acid Diffusion," Dow Electronic Materials, 2009 International Symposium on Extreme Ultraviolet Lithography, Oct. 19, 2009, 31 pages. 

Meagley, Robert P., "Fundamental Challenges for Lithographic Roadmap," Intel Corporation, Sep. 16, 2004, NSF/SRC ERC, 14 pages. 

Meagley, Robert P., Manager, Lithography, Fab Materials Operation (FMO), Intel Corporation, J. Vac. Sci. Tech. B, 24(4), Jul.I Aug. 2006, pp. 1822-1826. 

* cited by examiner 

Primary Examiner - Kathleen Duda 

(74) Attorney, Agent, or Firm - Hovey Williams LLP 

## (57) ABSTRACT 

The present invention provides novel methods of fabricating microelectronics structures, and the resulting structures formed thereby, using EUV lithographic processes. The method involves utilizing an assist layer immediately below the photoresist layer. The assist layer can either be directly applied to the substrate, or it can be applied to any interme› diate layer(s) that may be applied to the substrate. The pre› ferred assist layers are formed from spin-coatable, polymeric compositions. The inventive method allows reduced critical dimensions to be achieved with improved dose-to-size ratios, while improving adhesion and reducing or eliminating pat› tern collapse issues. 

US008968989B2 

## U.S. PATENT DOCUMENTS 

## OTHER PUBLICATIONS 

## 15 Claims, 18 Drawing Sheets 

