ene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate, and dipropylene glycol monoacetate; polyhydric alcohol derivatives including com› pounds having an ether bond, such as a monoalkylether ( e.g., monomethylether, monoethylether, monopropylether or monobutylether) or monophenylether of any of these polyhy› dric alcohols or compounds having an ester bond (among these, propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME) are prefer› able); cyclic ethers such as dioxane; esters such as methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methox› ypropionate, and ethyl ethoxypropionate; and aromatic organic solvents such as anisole, ethylbenzylether, cresylm› ethylether, diphenylether, dibenzylether, phenetole, butylphenylether, ethylbenzene, diethylbenzene, pentylben› zene, isopropylbenzene, toluene, xylene, cymene and mesi› tylene. 

[0539] These solvents can be used individually, or in com› bination as a mixed solvent. 

[0540] Among the aforementioned examples, PGMEA, PGME and EL are preferable. 

[0541] Further, among the mixed solvents, a mixed solvent obtained by mixing PGMEA with a polar solvent is prefer› able. The mixing ratio (weight ratio) of the mixed solvent can be appropriately determined, taking into consideration the compatibility of the PGMEA with the polar solvent, but is preferably in the range ofl:9 to 9: 1, more preferably from2:8 to 8:2. 

[0542] Specifically, when EL is mixed as the polar solvent, the PGMEA:EL weight ratio is preferably from 1:9 to 9:1, and more preferably from 2:8 to 8:2. Alternatively, when PGME is mixed as the polar solvent, the PGMEA:PGME 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. 

[0543] Further, as the component (5), a mixed solvent ofat 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. 

[0544] The amount of the organic solvent is not particularly limited, and is appropriately adjusted to a concentration which enables coating of a coating solution to a substrate, depending on the thickness of the coating film. In general, the organic solvent is used in an amount such that the solid content of the resist composition becomes within the range from 0.5 to 20% by weight, and preferably from 1 to 15% by weight. 

[0545] Dissolving of the resist materials in the component (S) can be conducted by simply mixing and stirring each of the above components together using conventional methods, and where required, the composition may also be mixed and dispersed using a dispersion device such as a dissolver, a homogenizer, or a triple roll mill. Furthermore, following mixing, the composition may also be filtered using a mesh, or a membrane filter or the like. 

[0546] As described above, the positive resist composition of the present invention is advantageous in that a resist pattern exhibiting an excellent resolution and an excellent shape can be formed. The reasons why these effects can be achieved have not been elucidated yet, but are presumed as follows. 

[0547] The positive resist composition of the present inven› tion contains a polymeric compound (Al) including a struc- 

tural unit (a0) represented by general formula (a0-1) and an acid generator (Bl) having an anion moiety represented by general formula (I). 

[0548] The structural unit (a0) has a relatively long side chain, and the side chain contains an oxygen atom (---0-) and a carbonyl group (-C(=O)-) which are electron-with› drawing groups. By virtue of the above features, in the poly› meric compound (Al) having the structural unit (a0), the acid dissociable, dissolution inhibiting group (R 1 ) on the terminal of the structural unit (a0) is more reliably dissociated. As a result, the efficiency of dissociation is improved, as compared to a conventional polymer. Further, a resist composition using such a component (Al) is capable of achieving an excellent dissolution contrast in the formation of a fine pattern. 

[0549] The anion moiety of the acid generator. (Bl) has a substituent containing an oxygen atom (X-Q$^{1}$-Y 1 -). By vir› tue of this feature, the anion moiety of such a component (B 1) exhibits a high polarity and has a three-dimensionally bulky structure, as compared to an anion moiety of a conventional acid generator, such as nonafluorobutanesulfonate. As a result, the acid generated from the component (Bl) upon exposure is chemically and physically suppressed from dif› fusing within a resist film, and the diffusion length is shorter than a conventional acid generator. Further, by using the component (Bl) in combination with the component (Al) having an electron-withdrawing group, the component (Bl) can be more uniformly distributed within a resist film. 

[0550] For the reasons as described above, according to the positive resist composition of the present invention using a combination of the component (Al) and the component (B 1 ), it is presumed that a satisfactory level in the difference between exposed portions and unexposed portions of the resist film in terms of solubility in an alkali developing solu› tion can be achieved, thereby improving the resolution. Fur› ther, it is presumed that a resist pattern exhibiting an excellent rectangularity can be formed. 

[0551] Moreover, according to the positive resist composi› tion of the present invention, in addition to the effects of the present invention described above, for example, the fluctua› tion in the pattern size depending on the change in the tem› perature during post exposure bake (PEB temperature) in the formation of a resist pattern (hereafter, this fluctuation is referred to as FEB sensitivity (PEBs)) can be suppressed. 

[0552] In the formation of a resist pattern, when the PEBs is deteriorated, a resist pattern having a desired size cannot be stably formed, so that it becomes difficult to reproduce a pattern having a fine size, 

[0553] Furthermore, the positive resist composition of the present invention exhibits excellent lithography properties with respect to exposure latitude (EL margin), mask error factor (MEF), depth of focus (DOE), in-plane uniformity of the pattern size (CDU), circularity and the like. 

[0554] The "EL margin" is the range of the exposure dose in which a resist pattern can be formed with a size within a predetermined range of variation from a target size, when exposure is conducted by changing the exposure dose, i.e., the range of the exposure dose in which a resist pattern faithful to the mask pattern can be formed. The larger the EL margin, the smaller the variation in the pattern size depending on the change in the exposure dose, thereby resulting in the improve› ment of the process margin. 

[0555] The MEF is a parameter that indicates how faith› fully mask patterns of differing dimensions can be repro› duced (i.e., mask reproducibility) by using the same exposure 

