patterning of the lower-layer organic film. This method is  capable of forming a pattern with a high aspect ratio. In other  words, in the multilayer resist method, a desired thickness can  be ensured by the lower-layer organic film, and as a result, the  thickness of the resist film can be reduced, and an extremely  fine pattern with a high aspect ratio can be formed.  The multilayer resist method can be broadly classified into  a method in which a double-layer structure consisting of an  upper-layer resist film and a lower-layer organic film is  formed ( a double-layer resist method), and a method in which  a multilayer structure having at least three layers consisting of  an upper-layer resist film, a lower-layer organic film and at  least one intermediate layer (a thin metal film or the like)  provided between the upper-layer resist film and the lower- layer organic film is formed (a three-layer resist method).  Liquid immersion lithography is a method in which the  region between the resist film and the lens at the lowermost  portion of the exposure apparatus is pre-filled with a solvent  ( an immersion medium) that has a larger refractive index than  the refractive index of air, and the exposure (immersion expo› sure) is conducted in this state.  The immersion medium preferably exhibits a refractive  index larger than the refractive index of air but smaller than  the refractive index of the resist film that is to be exposed. The  refractive index of the immersion medium is not particularly  limited as long at it satisfies the above requirements.  Examples of this immersion medium which exhibits a  refractive index that is larger than the refractive index of air  but smaller than the refractive index of the resist film include  water, fluorine-based inert liquids, silicon-based solvents and  hydrocarbon-based solvents.  Specific examples of the fluorine-based inert liquids  include liquids containing a fluorine-based compound such as  C$_{3}$HC1$_{2}$F$_{5}$ ,  C$_{4}$ F$_{9}$OCH$_{3}$ ,  C$_{4}$F$_{9}$OC$_{2}$H$_{5 }$ or C$_{5}$ H$_{3}$F$_{7 }$ as the main  component, which have a boiling point that is preferably  within a range from 70 to 180°  C., and more preferably from  80 to 160°  C. A fluorine-based inert liquid having a boiling  point within the above-mentioned range is advantageous in  that the removal of the immersion medium after the exposure  can be conducted by a simple method.  As the fluorine-based inert liquid, a perfluoroalkyl com- pound in which all of the hydrogen atoms of the alkyl group  are substituted with fluorine atoms is particularly desirable.  Examples of these perfluoroalkyl compounds include per› fluoroalkylether compounds and perfluoroalkylamine com› pounds.  Specifically, one example of a suitable perfluoroalkylether  compound is perfluoro(2-butyl-tetrahydrofuran) (boiling  point: 102°  C.), and one example of a suitable perfluoroalky› lamine compound is perfluorotributylamine (boiling point:  174°  C).  As the immersion medium, water is preferable in terms of  cost, safety, environmental issues and versatility.  A polymeric compound of the present invention has a  structural unit (a0) represented by the general formula (a0-0- 1) shown below.  The rinse treatment (washing treatment) using a rinse liq- uid may be performed using a conventional rinse method.  Examples of methods that may be used include methods in  which the rinse liquid is discharged continuously onto the  substrate while the substrate is spun at a constant rate (spin  coating methods), methods in which the substrate is dipped in  the rinse liquid for a predetermined period of time ( dipping  methods) and methods in which the rinse liquid is sprayed  onto the substrate surface (spray methods).  <<Polymeric Compound>>  Examples of the organic solvent contained within the rinse  liquid used for the rinse treatment performed following a  solvent developing process include those organic solvents  among the solvents described above for the organic solvent of  the organic developing solution which exhibit poor dissolu› tion of the resist pattern. Examples of typical solvents that  may be used include one or more solvents selected from  among hydrocarbon solvents, ketone-based solvents, ester› based solvents, alcohol-based solvents, amide-based solvents  and ether-based solvents. Among these, at least one solvent  selected from among hydrocarbon solvents, ketone-based  solvents, ester-based solvents, alcohol-based solvents and  amide-based solvents is preferred, at least one solvent  selected from among alcohol-based solvents and ester-based  solvents is more preferred, and an alcohol-based solvent is  particularly desirable.  The developing treatment can be performed using a con› ventional developing method. Examples of developing meth› ods that may be used include methods in which the substrate  is dipped in the developing solution for a predetermined  period of time ( dipping methods), methods in which the  developing solution is placed and held on the surface of the  substrate by surface tension for a predetermined period of  time (puddle methods), methods in which the developing  solution is sprayed onto the substrate surface (spray meth› ods), and methods in which the substrate is spun at a constant  rate, and a developing solution discharge nozzle is then  scanned across the substrate at a constant rate while the <level- oping solution is discharged from the nozzle ( dynamic dis› pensing methods).  In those cases where a surfactant is added, the amount of  the surfactant is typically within a range from 0.001 to 5% by  weight, more preferably from 0.005 to 2% by weight, and still  more preferably from 0.01 to 0.5% by weight, relative to the  total weight of the organic developing solution.  Conventional additives may be added to the organic devel› oping solution as required. Examples of these additives  include surfactants. There are no particular limitations on the  surfactants, and ionic and nonionic fluorine-based surfactants  and/or silicon-based surfactants can be used.  The organic solvent within the organic developing solution  that is used in the solvent developing process may be selected  appropriately from among any of the conventional solvents  capable of dissolving the component (A) (the component (A)  prior to exposure). Specific examples of organic solvents that  may be used include polar solvents such as ketone-based  solvents,  ester-based  solvents,  alcohol-based  solvents,  amide-based solvents and ether-based solvents, and hydro- carbon solvents.  Examples of the alkali developing solution used in an alkali  developing process include 0.1 to 10% by weight aqueous  solutions oftetramethylammonium hydroxide (TMAH).  154  US  9,104,101 B2  153 