romethyl group, -CH 2 -CF 3 , ----CH 2 ----CF 2 -CF 3 , --CH (CF 3 ) 2 , ----CH 2 ----CH 2 ----CF 3 , and -CH 2 ----CH 2 ----CF 2 - CF2-CF2-CF3 are most preferable. 

[0518] The weight average molecular weight (Mw) (the polystyrene equivalent value determined by gel permeation chromatography) of the component (F) is preferably 1,000 to 50,000, more preferably 5,000 to 40,000, and most preferably 10,000 to 30,000. When the Mw of the compo› nent (F) is no more than the upper limit of the above› mentioned range, the resist composition exhibits a satisfac› tory solubility in a resist solvent. On the other hand, when the Mw is at least as large as the lower limit of the above-mentioned range, dry etching resistance and the cross-sectional shape of the resist pattern becomes satisfac› tory. 

[0519] Further, the dispersity (Mw/Mn) of the component (F) is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, and most preferably 1.2 to 2.5. 

[0520] As the component (F), one type may be used alone, or two or more types may be used in combination. 

[0521] When the resist composition contains the compo› nent (F), the component (F) is used in an amount within a range from 0.5 to 10 parts by weight, relative to 100 parts by weight of the component (A). 

[0522] If desired, other miscible additives can also be added to the resist composition of the present invention. Examples of such miscible additives include additive resins for improving the performance of the resist film, dissolution inhibitors, plasticizers, stabilizers, colorants, halation pre› vention agents, and dyes. 

[0523] <<Organic Solvent (S)>> 

[0524] The resist composition of the present embodiment may be prepared by dissolving the resist materials for the resist composition in an organic solvent (hereafter, referred to as "component (S)"). 

[0525] The component (S) may be any organic solvent which can dissolve the respective components to give a homogeneous solution, and any organic solvent can be appropriately selected from those which have been conven› tionally known as solvents for a chemically amplified resist composition. 

[0526] Examples of the component (S) include lactones such as y-butyrolactone; ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl-n-pentyl ketone, methyl isopentyl ketone, and 2-heptanone; polyhydric alco› hols, such as ethylene glycol, diethylene glycol, propylene glycol and dipropylene glycol; compounds having an ester bond, such as ethylene glycol monoacetate, diethylene gly› col monoacetate, propylene glycol monoacetate, and dipro› pylene glycol monoacetate; polyhydric alcohol derivatives including compounds having an ether bond, such as a monoalkylether (e.g., monomethylether, monoethylether, monopropylether or monobutylether) or monophenylether of any of these polyhydric alcohols or compounds having an ester bond (among these, propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME) are preferable); cyclic ethers such as dioxane; esters such as methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, and ethyl ethoxypro› pionate; aromatic organic solvents such as anisole, ethyl› benzylether, cresylmethylether, diphenylether, dibenzyle› ther, phenetole, butylphenylether, ethylbenzene, 

diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymene and mesitylene; and dimethylsulfoxide (DMSO). 

[0527] The component (S) can be used individually, or in combination as a mixed solvent. 

[0528] Among these, PGMEA, PGME, y-butyrolactone, EL and cyclohexanone are preferable. 

[0529] Further, among the mixed solvents, a mixed sol› vent obtained by mixing PGMEA with a polar solvent is preferable. The mixing ratio (weight ratio) of the mixed solvent can be appropriately determined, taking into con› sideration the compatibility of the PGMEA with the polar solvent, but is preferably in the range of 1:9 to 9:1, more preferably from 2:8 to 8:2. 

[0530] Specifically, when EL or cyclohexanone is mixed as the polar solvent, the PGMEA:EL or cyclohexanone weight ratio is preferably from 1:9 to 9:1, and more pref› erably from 2:8 to 8:2. Alternatively, when PGME is mixed as the polar solvent, the PGMEA:PGME weight ratio is preferably from 1:9 to 9: 1, more preferably from 2:8 to 8:2, and still more preferably 3:7 to 7:3. Furthermore, a mixed solvent of PGMEA, PGME and cyclohexanone is also preferable. 

[0531] Further, as the component (S), a mixed solvent of at least one of PGMEA and EL with y-butyrolactone is also preferable. The mixing ratio (former:latter) of such a mixed solvent is preferably from 70:30 to 95:5. 

[0532] The amount of the component (S) is not particu› larly limited, and is appropriately adjusted to a concentration which enables coating of a coating solution to a substrate. In general, the component (S) is used in an amount such that the solid content of the resist composition becomes within the range from 1 to 20% by weight, and preferably from 2 to 15% by weight. 

[0533] According to the resist composition of the present embodiment described above, sensitivity may be enhanced in the formation of a resist pattern, and the shape of the resist pattern may be further improved. 

[0534] In the resist composition of the present embodi› ment, as the base component (A), a polymeric compound (Al) having a structural unit (a0) represented by general formula (a0-1) is used. The structural unit (a0) has an acid dissociable group represented by general formula (a0-rl-1) on the terminal of the side-chain thereof. The acid disso› ciable group contains a quaternary carbon atom (Ya 0 ) and a polar group. 

[0535] By virtue of the acid dissociable group containing a quaternary carbon atom (Ya 0 ), acid dissociability upon exposure in the formation of a resist pattern may be reliably improved, as compared to the case where the acid disso› ciable group contains a tertiary carbon atom. Therefore, the reactivity may be improved, and sensitivity may be enhanced. In addition, a high dissolution contrast may be obtained by developing. 

[0536] Further, by virtue of the acid dissociable group containing a polar group, solubility in a developing solution containing an organic solvent may be maintained at a low level. Therefore, in a solvent developing process, in the case where the acid dissociable group is not decomposed and remains at exposed portions of the resist film, or in the case where a decomposition product remains in the resist film, the dissolution rate of the exposed portions of the resist film in an organic developing solution may be suppressed from being increased, such that film loss of pattern portions may 

