14  US 8,968,989 B2  13  TABLE I-continued  Example 8  Lithography Results  Example 9  Lithography Results  forming a photoresist layer on said assist layer; and  spin coating a composition to form an assist layer on said  substrate, or on said one or more intermediate layers, if  present, said assist layer being a cured film comprising at  least about 0.01 % by weight metal, based upon the total  weight of the cured film taken as 100% by weight;  providing a substrate, said substrate optionally including  one or more intermediate layers thereon;  .  1.  A method of forming a structure, said method compris› mg:  We claim:  Formulation 6 was used in a multilayer stack that included  an underlay er, the assist layer, and an EUV resist. Without the  use of Formulation 6, the Dose to Size was measured to be 9.4  ml/cm 2 .  Use of Formulation 6 as an assist layer reduced the  J?ose to Size to 7 .8 mJ/cm $^{2 }$and allowed patterning of 28 nm  Imes and spaces, shown in FIG.  18.  subjecting at least a portion of said photoresist layer to  EUV radiation.  forming a photoresist layer on said assist layer; and  forming an assist layer on said substrate, or on said one or  more intermediate layers, if present, said assist layer  formed from a composition comprising a crosslinking  agent and being a cured film comprising at least about  0.01 % by weight metal, based upon the total weight of  the cured film taken as 100% by weight;  providing a substrate, said substrate optionally including  one or more intermediate layers thereon;  .  15.  A method of forming a structure, said method compris› mg:  14.  The method of claim  1,  said substrate including one or  m~re intermediate layers, one of said intermediate layers  bemg the uppermost intermediate layer, and said uppermost  intermediate layer being a carbon layer.  13.  The method of claim  1,  wherein said assist layer is  formed from a composition that is substantially free of pho› toacid generators.  12.  The method of claim  8,  wherein said forming a pattern  in said photoresist layer comprises contacting said photore› sist layer with a developer so as to remove some of said  photoresist layer.  11.  The method of claim  9,  wherein said pattern has a  resolution ofless than about 32 nm.  10.  The method of claim  9,  wherein said transferring said  pattern comprises etching said assist layer; intermediate lay› ers, if present; and said substrate.  Three successive etches were performed. The first etch was  used to open the assist layer, and used CF  4 gas at35 seem flow,  50 mTorr pressure, 100 W power, and 357 V DC bias. The  second etch was used to open the SOC, and usedAr:CO$_{2 }$at 25  seem flow for both gases, 20 mTorr pressure, 300 W power,  and 736 V DC bias. Finally, the third etch was also for the  SOC, and used O$_{2}$ :N$_{2 }$ at 20 seem flow for both gases, 20  mTorr pressure, 300 W power, and 705 V DC bias. Pattern  transfer was successful, but some CD edge trimming was  observed. FIGS.  14-17  show these results.  _9.  The method_ of claim  8,  further comprising transferring  said pattern to said assist layer; to said intermediate layers, if  present; and to said substrate.  A spin on carbon hardmask, Opti Stackfi SOCll0D-310  (Brewer Science, Inc.) was coated onto a silicon wafer at  1,500 rpm for 60 seconds, followed by baking at 205°  C. for  60 seconds to form a film having a thickness of 100 nm.  Various dilutions of Formulation 6 were then coated onto  wafers at -1,500 rpm for 60 seconds, followed by baking at  205°  C. for 60 seconds to form films of various thicknesses.  An ArF resist was applied to the film followed by a 105°  C.  bake for 60 seconds, then an exposure at a wavelength of 193  nm and developing with 0.26N TMAH for 30 seconds.  8.  The method of claim  1,  further comprising forming a  pattern in said photoresist layer after said subjecting of said  photoresist layer to EUV radiation.  7.  The method of claim  1,  wherein said subjecting said  photoresist layer to EUV radiation is carried out with a dose  of from about 5 mJ/cm$^{2 }$to about 100 mJ/cm 2 .  6.  The method of claim  1,  wherein said assist layer is  formed from a composition comprising a crosslinking agent.  5.  The method of claim  1,  wherein said substrate is selected  from the group consisting of silicon, Si Ge, Si 0 2 ,  Si$_{3}$N$_{4}$ ,  alu› minum, Al$_{2}$O$_{3}$ , hafnium, zirconium, titanium, magnesium,  tungsten, tungsten silicide, gallium arsenide, germanium,  tantalum, tantalum nitride, indium, and indium phosphide.  4.  The method of claim  3,  wherein said metal or metal  d~rivative is selected from the group consisting of Si, SiO$_{2}$ ,  S~$_{3}$N$_{4}$ ,  AIN, Al$_{2}$O$_{3}$ ,  ZrC, ZrO$_{2}$ ,  Hf, HfO$_{2}$ ,  TiN, TiO, TiO$_{2}$ ,  T1$_{2}$O$_{3}$ ,  Mg$_{3}$N$_{2}$ ,  MgO, W, WO, WO$_{2}$ ,  and WO$_{3}$ .  3.  The method of claim  1,  said assist layer being formed  from a composition comprising a metal or metal derivative  sele~ted from the group consisting of metal halides, metal  carbides, metal sulfides, metal nitrides, metal oxides, and  mixtures thereof.  2.  The method of claim  1,  said metal being selected from  the group consisting of Al, Mg, Na, Zn, Co, Cu, Ga, Ge, Hf,  Ti, Zr, Se, Ni,  V,  Ar, Sc, and Si.  subjecting at least a portion of said photoresist layer to  EUV radiation.  Dose to Size for Various Assist Layer Formulations  30-nm  26-nm  Dose to size % Reduction Dose to size % Reduction  Formulation  mJlcm 2  in dose  mJlcm 2  in dose  lC  9.4  19  2  8.4  28  9.5  21  3  6.8  42  7.6  37  4  7.3  37  8.0  34  E $^{2}$Stack  fi  11.7  NIA  12.1  NIA  AL412  *  *  *  *  * 