The present invention relates to a process for labeling compounds comprising thiol moieties with 3-arylpropiolonitrile compounds, to 3-arylpropiolonitrile compounds substituted with tag moieties and to specific 3-arylpropiolonitrile linkers.

The present invention relates to a process for labeling compounds comprising thiol moieties with 3-arylpropiolonitrile compounds, to 3-arylpropiolonitrile compounds substituted with tag moieties and to specific 3-arylpropiolonitrile linkers.

A salt represented by the formula (I): ##STR00001## wherein R.sup.1 represents a C1 to C12 alkyl group in which a methylene group can be replaced by an oxygen atom or a carbonyl group; Q.sup.1 and Q.sup.2 each independently represent a fluorine atom or a C1 to C6 perfluoroalkyl group; A.sup.1 represents a lactone ring-containing group which has 4 to 24 carbon atoms; R.sup.2 represents an acid-labile group; and m represents an integer of 0 to 3.

A salt represented by the formula (I): ##STR00001## wherein R.sup.1 represents a C1 to C12 alkyl group in which a methylene group can be replaced by an oxygen atom or a carbonyl group; Q.sup.1 and Q.sup.2 each independently represent a fluorine atom or a C1 to C6 perfluoroalkyl group; A.sup.1 represents a lactone ring-containing group which has 4 to 24 carbon atoms; R.sup.2 represents an acid-labile group; and m represents an integer of 0 to 3.

Provided are: a sulfonium salt monomer to be used as a sulfonium salt quencher, which is a material of a polymer to be contained in a chemically amplified resist composition that exhibits superior solubility in solvents and has superior lithographic performance with high sensitivity and high contrast in photolithography with use of a high-energy ray, and also has superior etching resistance with durability against pattern collapse even in fine patterning; a sulfonium salt quencher containing the sulfonium salt monomer; a polymer containing a repeating unit derived from the sulfonium salt quencher; a chemically amplified resist composition containing a base polymer containing the polymer; and a patterning method with the chemically amplified resist composition. A sulfonium salt monomer represented by the following general formula (a):

##STR00001##

Provided are: a sulfonium salt monomer to be used as a sulfonium salt quencher, which is a material of a polymer to be contained in a chemically amplified resist composition that exhibits superior solubility in solvents and has superior lithographic performance with high sensitivity and high contrast in photolithography with use of a high-energy ray, and also has superior etching resistance with durability against pattern collapse even in fine patterning; a sulfonium salt quencher containing the sulfonium salt monomer; a polymer containing a repeating unit derived from the sulfonium salt quencher; a chemically amplified resist composition containing a base polymer containing the polymer; and a patterning method with the chemically amplified resist composition. A sulfonium salt monomer represented by the following general formula (a):

##STR00001##