A method for preparing high-purity taurine and salt by reacting ethylene oxide with bisulfite to generate isethionate, performing an ammonolysis reaction on the isethionate in combination with ammonia and a metal salt, evaporating the reaction solution and subjecting the concentrated solution to ion exchange to obtain an adsorption solution, extracting taurine from the adsorption solution, eluting adsorbed metal cations from the ion exchange system by an acid, and separately collecting the eluate containing a salt.

A sulfonic acid derivative, wherein the sulfonic acid derivative is represented by the following general formula (1):

R.sup.1COOCH.sub.2CH.sub.2CFHCF.sub.2SO.sub.3.sup.−M.sup.+  (1)

where: R.sup.1 represents a monovalent organic group having carbon number of 1 to 200, having at least one hydroxyl group and optionally having a substituent other than the hydroxyl group; and M.sup.+ represents a counter cation.

A sulfonic acid derivative, wherein the sulfonic acid derivative is represented by the following general formula (1):

R.sup.1COOCH.sub.2CH.sub.2CFHCF.sub.2SO.sub.3.sup.−M.sup.+  (1)

where: R.sup.1 represents a monovalent organic group having carbon number of 1 to 200, having at least one hydroxyl group and optionally having a substituent other than the hydroxyl group; and M.sup.+ represents a counter cation.

Provided are a salt capable of producing a resist pattern with satisfactory CD uniformity (CDU), an acid generator, and a resist composition comprising the same. Disclosed are a salt represented by formula (I), an acid generator, and a resist composition comprising the same:

##STR00001##

wherein R.sup.4, R.sup.5, R.sup.7 and R.sup.8 each represent a halogen atom, a haloalkyl group or a hydrocarbon group; A.sup.1 and A.sup.2 each represent a hydrocarbon group, the hydrocarbon group may have a substituent, and —CH.sub.2— included in the hydrocarbon group may be replaced by —O—, —CO—, —S— or —SO.sub.2—; ml represents an integer of 1 to 5, m2, m4, m5 and m8 represent an integer of 0 to 5, m7 represents an integer of 0 to 4, 1≤m1+m7≤5, 0≤m2+m8≤5; and AI.sup.− represents an organic anion.

A radiation-sensitive resin composition includes: a polymer which has a first structural unit including a phenolic hydroxyl group, and a second structural unit represented by formula (1); and a radiation-sensitive acid generating agent which has a compound represented by formula (2). R.sup.1 represents a hydrogen atom, or the like; R.sup.2 represents a hydrogen atom or the like; and R.sup.3 represents a divalent monocyclic alicyclic hydrocarbon group having 3 to 12 ring atoms. Ar.sup.1 represents a group obtained by removing (q+1) hydrogen atoms on an aromatic ring from an arene formed by condensation of at least two benzene rings; R.sup.4 represents a monovalent organic group having 1 to 20 carbon atoms; q is an integer of 0 to 7; and R.sup.5 represents a halogen atom, a hydroxy group, a nitro group, or a monovalent organic group having 1 to 20 carbon atoms, or the like.

##STR00001##

A radiation-sensitive resin composition includes: a polymer which has a first structural unit including a phenolic hydroxyl group, and a second structural unit represented by formula (1); and a radiation-sensitive acid generating agent which has a compound represented by formula (2). R.sup.1 represents a hydrogen atom, or the like; R.sup.2 represents a hydrogen atom or the like; and R.sup.3 represents a divalent monocyclic alicyclic hydrocarbon group having 3 to 12 ring atoms. Ar.sup.1 represents a group obtained by removing (q+1) hydrogen atoms on an aromatic ring from an arene formed by condensation of at least two benzene rings; R.sup.4 represents a monovalent organic group having 1 to 20 carbon atoms; q is an integer of 0 to 7; and R.sup.5 represents a halogen atom, a hydroxy group, a nitro group, or a monovalent organic group having 1 to 20 carbon atoms, or the like.

##STR00001##

A sulfonium salt represented by a following general formula (1),

##STR00001##

wherein in the general formula (1), each of R.sup.1 to R.sup.3 is independently an alkyl group, an aryl group, or a heteroaryl group;

at least one carbon-carbon single bond contained in the alkyl group is optionally substituted with a carbon-carbon double bond or a carbon-carbon triple bond;

at least one methylene group contained in the alkyl group is optionally substituted with at least one divalent heteroatom-containing group;

Ar.sup.1 is an arylene group;

at least one of R.sup.1, R.sup.2, R.sup.3 and Ar.sup.1 has at least one substituent (R);

at least two of R.sup.1 to R.sup.3, Ar.sup.1, and substituent (R) optionally form a ring;

A is a divalent group selected from a group consisting of —S—, —SO—, and —SO.sub.2—;

Ar.sup.1 is substituted with A at an ortho-position with respect to a sulfonio group (S.sup.+); and

X.sup.− is an anion.

A sulfonium salt represented by a following general formula (1),

##STR00001##

wherein in the general formula (1), each of R.sup.1 to R.sup.3 is independently an alkyl group, an aryl group, or a heteroaryl group;

at least one carbon-carbon single bond contained in the alkyl group is optionally substituted with a carbon-carbon double bond or a carbon-carbon triple bond;

at least one methylene group contained in the alkyl group is optionally substituted with at least one divalent heteroatom-containing group;

Ar.sup.1 is an arylene group;

at least one of R.sup.1, R.sup.2, R.sup.3 and Ar.sup.1 has at least one substituent (R);

at least two of R.sup.1 to R.sup.3, Ar.sup.1, and substituent (R) optionally form a ring;

A is a divalent group selected from a group consisting of —S—, —SO—, and —SO.sub.2—;

Ar.sup.1 is substituted with A at an ortho-position with respect to a sulfonio group (S.sup.+); and

X.sup.− is an anion.

A monomer has the structure

##STR00001##

wherein R is an organic group comprising a polymerizable carbon-carbon double bond or carbon-carbon triple bond; X and Y are independently at each occurrence hydrogen or a non-hydrogen substituent; EWG1 and EWG2 are independently at each occurrence an electron-withdrawing group; p is 0, 1, 2, 3, or 4; n is 1, 2, 3, or 4; and M.sup.+ is an organic cation. A polymer prepared from monomer is useful as a component of a photoresist composition.

A monomer has the structure

##STR00001##

wherein R is an organic group comprising a polymerizable carbon-carbon double bond or carbon-carbon triple bond; X and Y are independently at each occurrence hydrogen or a non-hydrogen substituent; EWG1 and EWG2 are independently at each occurrence an electron-withdrawing group; p is 0, 1, 2, 3, or 4; n is 1, 2, 3, or 4; and M.sup.+ is an organic cation. A polymer prepared from monomer is useful as a component of a photoresist composition.