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<Basic Compound> 

As the basic compound, the following Compounds C-1 to C-3 were used. 

C-1: 2,4,5-Triphenylimidazole 

C-2: Tetrabutylammonium hydroxide 

C-3: 1,5-Diazabicyclo[ 4.3.0]non-5-ene 

<Surfactant> 

As the surfactant, the following W-1 to W-4 were used. 

W-1: Megaface Fl 76 (produced by DIC Corp.; fluorine-con› taining) 

W-3: Polysiloxane Polymer KP-341 (produced by Shin-Etsu Chemical Co., Ltd.; silicon-containing) 

W-4: Troysol S-366 (produced by Troy Chemical; fluorine› containing) 

<Solvent> 

As the solvent, the following Al to A4, Bl and B2 were used. These solvents were appropriately mixed and used. 

Al: Propylene glycol monomethyl ether acetate 

A2: 2-Heptanone 

A3: Cyclohexanone 

A4: y-Butyrolactone 

Bl: Propylene glycol monomethyl ether 

B2: Ethyl lactate 

As apparent from the results in Table 2, with respect to ArF 65 exposure, in Comparative Examples IA and 2A using Com› parative Compounds 1 and 2 (both are compounds described 

-continued 

in Patent Document 2 (JP-A-2011-16746)) as the acid gen› erator, the sensitivity, resolution and LER were poor, the variation of sensitivity after aging was large, and the outgas› sing was frequently generated. 

The reason why in Comparative Examples IA and 2A, the sensitivity was poor, particularly, as to the aging stability, the variation of sensitivity after aging was large, is not clearly known but is considered because the decomposition effi- ciency (acid generation efficiency) of Comparative Com› pounds 1 and 2 during exposure is low probably due to low solubility of Comparative Compounds 1 and 2 for the solvent in the composition. 

On the other hand, in Examples IA to 19A using, as the acid generator, (Al) a compound represented by formula (Z 1) where when -L$_{1}$-R$_{1}$-A$_{1 }$ is substituted at the para-position relative to s+, L$_{1 }$ is not an oxygen atom, the sensitivity, reso› lution and LER were excellent, the variation of sensitivity after aging was small, and the outgassing was little generated. 

The reason why in Examples IA to 19A using the com- pound (Al) according to the present invention, the sensitivity and LER were excellent, is not clearly known but is consid› ered that the compound (Al) represented by formula (Zl) is configured to have a specific betaine structure of not allowing L$_{1 }$to be an oxygen atom when -L$_{1}$-R$_{1}$-A$_{1 }$is substituted at the para-position relative to s+, whereby the decomposition effi› ciency (acid generation efficiency) of the compound (Al) during exposure can be enhanced, the solubility of the com- pound (Al) for the solvent in the composition can be increased, the compound (Al) can be prevented from precipi› tating in the resist composition during storage and exhibit excellent aging stability (little variation of sensitivity after aging), and because of high acid generation efficiency, a large amount of acid can be generated, resulting in high sensitivity andlowLER. 

Furthermore, it is considered that the compound (Al) according to the present invention has a betaine structure having an anion moiety and a cation moiety in the same molecule and thanks to this configuration, the cation moiety decomposes during exposure to reduce the molecular weight, as a result, the solubility of the exposed area for an alkali developer is enhanced to increase the dissolution contrast, making it possible to achieve high resolution. 

Resist solutions were prepared in the same manner as in Example IA except for adding 0.06 g of the polymer shown below (the compositional ratio is in terms of molar ratio) to the composition of Example IA, and the solution was coated to obtain a resist film. The obtained resist film was pattern› wise exposed through an immersion liquid (pure water) by using an ArF excimer laser immersion scanner (XTl 700i, manufactured by ASML, NA: 1.2), and a pattern was formed in the same manner as in Example Al. 

The obtained pattern was evaluated for the sensitivity, reso› lution, LER, aging stability (variation of sensitivity after aging), and outgassing performance in the same manner as in Example A. As a result, it was confirmed that the sensitivity, resolution and LER are excellent, the variation of sensitivity after aging is small, and the outgassing is little generated. 

The reason therefor is as described in Example A. 

## ExampleB 

