(45)  Date of Patent:  *Mar. 3, 2015  (IO)  Patent No.:  US 8,968,989 B2  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  (60)  Provisional application No. 61/562,166, filed on Nov.  21, 2011.  (51)  Int. Cl.  (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.  (56)  References Cited  U.S. PATENT DOCUMENTS  FOREIGN PATENT DOCUMENTS  OTHER PUBLICATIONS  (57)  ABSTRACT  15 Claims, 18 Drawing Sheets  (65)  Prior Publication Data  Related U.S. Application Data  G03F  7126  (2006.01)  G03F  7109  (2006.01)  G03F  7120  (2006.01)  G03F  7111  (2006.01)  B82Y 30/00  (2011.01)  B82Y 40/00  (2011.01)  6,140,023 A  *  6,740,469 B2  8,257,910 Bl  2007/0148602 Al  2009/0123878 Al  2009/0297784 Al  2011/0123779 Al  10/2000 Levinson et al .............. 430/313  5/2004 Krishnamurthy et al.  9/2012 Guerrero et al.  6/2007 Lee et al.  5/2009 Miyoshi et al.  12/2009 Xu et al.  5/2011 Fuller et al.  US008968989B2  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  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.  US 2013/0129995 Al  May 23, 2013 