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As the acid generator used in the present invention, in addition to a low molecular compound, a compound wherein a group generating an acid upon irradiation with the actinic rays or radiation has been introduced into the main chain or a side chain of the high molecular compound can also be used. As further described above, in a case where a group generat› ing an acid upon irradiation with the actinic rays or radiation is present in the repeating units of the high molecular com› pound (A) used in the present invention, apart from the high molecular compound (A) of the present invention, it does not matter if the acid generator (B) is not present therein. 

It is preferable that the acid generator be a compound generating an acid upon irradiation with an electron beam or extreme ultraviolet ray. 

In the present invention, the examples of the preferable onium compounds can include a sulfonium compound repre› sented by the following general formula (1 ), or an iodonium compound represented by the general formula (2). 

In the general formulae (1) and (2), each of Rau Ra$_{2}$ , Ra$_{3}$ , Ra$_{4 }$ and Ras represents an organic group. 

x- represents an organic anion. 

Next, the sulfonium compound represented by the general formula (1) and the iodonium compound represented by the general formula (2) will be further described. 

While each ofRa$_{1 }$to Ra$_{3 }$ of the general formula (1) and Ra$_{4 }$ and Ras of the general formula (2) represent an organic group, preferably at least one ofRa$_{1 }$ to Ra$_{3}$ , and at least one ofRa$_{4 }$ and Ras be an aryl group, respectively. As an aryl group, a phenyl group, and a naphthyl group are preferable, and fur› ther preferred is a phenyl group. 

The examples of the organic anion of x- in the general formulae (1) and (2) include sulfonic acid anion, carboxylic acid anion, bis(alkylsulfonyl)amid anion, and tris(alkylsulfo› nyl)methide anion, and the like, and preferably an organic anion represented by the following general formulae (3 ), ( 4) or (5), more preferably an organic anion represented by the following general formula (3). 

In the formulae (3), ( 4) and (5), Rei, Rc$_{2}$ , Rc$_{3 }$ and Rc$_{4 }$ represents independently an organic group, respectively. 

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The organic anion of the above x- corresponds to sulfonic acid, imide acid and methide acid, and the like, which are an acid generating upon irradiation with the actinic rays or radia› tion such as an electron beam or extreme ultraviolet ray. 

The examples of the organic groups of the above Rc1 to Rc4 can include an alkyl group, an aryl group, or a group in which a plurality thereof are connected to one another. Among these organic groups, more preferred is an alkyl group of which I-position is substituted with a fluorine atom or with a fluo› roalkyl group, and a phenyl group of which the position is substituted with a fluorine atom or with a fluoroalkyl group. By having a fluorine atom or a fluoroalkyl group, the acidity of the acid generated by the light irradiation increases, and the sensitivity rises. However, it is preferable that the terminal group do not have a fluorine atom as a substituent. 

In the present invention, in view of suppressing the diffu› sion of the acid generated by the exposure toward the unex› posed area and improving resolution or pattern profile, the aforementioned acid generator (B) is preferably a compound generating an acid having a size of 130 A $^{3 }$or more in volume (more preferably sulfonic acid), more preferably a compound generating an acid having a size of 190 A $^{3 }$or more in volume (more preferably sulfonic acid), still more preferably a com› pound generating an acid having a size of 270 A $^{3 }$or more in volume (more preferably sulfonic acid), and particularly pref› erably a compound generating an acid having a size of 400 A 3 or more in volume (more preferably sulfonic acid). However, in view of the sensitivity or the solubility in the coating solvent, the above-described volume is preferably 2000 A $^{3 }$or less, further preferably 1500 A $^{3 }$or less. This volume value is determined by using "WinMOPAC" available from FUJITSU LIMITED. That is to say, first, the chemical structure of the acid according to each example was input, and then, using this structure as an initial structure, the most stable conformation of each acid was determined by molecular force field calcu› lation using the MM3 method, and thereafter, with respect to these most stable conformation, molecular orbital calculation using the PM3 method was performed, which enables to compute the "accessible volume" of each acid. 

The particular preferable acid generators for use in the present invention are illustrated below. Incidentally, the com› puted volume value is affixed to a part of these examples (unit A 3 ). In addition, the computed value obtained here is the volume value of an acid wherein a proton is attached to an anion part. 

(3) 

(4) 

( 5 

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