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. 

Examples of the alkali developing solution used in an alkali developing process include 0.1 to 10% by weight aqueous solutions oftetramethylammonium hydroxide (TMAH). 

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. 

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. 

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. 

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). 

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 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>> 

A polymeric compound of the present invention has a structural unit (a0) represented by the general formula (a0-0- 1) shown below. 

