Compounds of the formula (I) and (IA) wherein X is —O(CO)—; R.sub.1 is C.sub.1-C.sub.12haloalkyl or C.sub.6-C.sub.10haloaryl; R.sub.2 is located in position 7 of the coumarinyl ring and is OR.sub.8; R.sub.2a, R.sub.2b and R.sub.2C independently of each other are hydrogen; R.sub.3 is C.sub.1-C.sub.8haloalkyl or C.sub.1-C.sub.8haloalkyl; R.sub.4 is hydrogen; and R.sub.8 is C.sub.1-C.sub.6alkyI; are suitable as photosensitive acid donors in the preparation of photoresist compositions such as used for example in the preparation of spacers, insulating layers, interlayer dielectric films, insulation layers, planarization layers, protecting layers, overcoat layers, banks for electroluminescence displays and liquid crystal displays (LCD).

##STR00001##

A resist composition including: a compound including an anion moiety and a cation moiety and represented by the following Formula (bd1); and an organic solvent having a hydroxyl group in which Rx.sup.1 to Rx.sup.4 each represent a hydrocarbon group or a hydrogen atom, or may be bonded to each other to form a ring structure; Ry.sup.1 and Ry.sup.2 each independently represent a hydrocarbon group or a hydrogen atom, or may be bonded to each other to form a ring structure; Rz.sup.1 to Rz.sup.4 each represent a hydrocarbon group or a hydrogen atom, or may be bonded to each other to form a ring structure; at least one of Rx.sup.1 to Rx.sup.4, Ry.sup.1 and Ry.sup.2 and Rz.sup.1 to Rz.sup.4 has an anionic group; and M.sup.m+ represents an organic cation) ##STR00001##

A resist composition comprising a base polymer and an acid generator containing a sulfonium salt having the formula (1) or an iodonium salt having the formula (2). ##STR00001##

A resin having a small linear thermal expansion coefficient and a low absorbance is provided. The resin is characterized by including at least one structure selected from structures represented by the following general formulae (1) and (2):

##STR00001##

Provided are a polymer that can be favorably used as a positive resist having a high γ value and a positive resist composition that can favorably form a high-resolution pattern. The polymer includes an α-methylstyrene unit and a methyl α-chloroacrylate unit, and has a molecular weight distribution (Mw/Mn) of less than 1.48. The positive resist composition contains the aforementioned polymer and a solvent.

Provided are a polymer that can be favorably used as a positive resist having a high γ value and a positive resist composition that can favorably form a high-resolution pattern. The polymer includes an α-methylstyrene unit and a methyl α-chloroacrylate unit, and has a molecular weight distribution (Mw/Mn) of less than 1.48. The positive resist composition contains the aforementioned polymer and a solvent.

A positive resist composition comprising a base polymer comprising recurring units having a carboxyl group whose hydrogen is substituted by a pyridine ring-containing tertiary hydrocarbyl group.

A positive resist composition comprising a base polymer comprising recurring units having a carboxyl group whose hydrogen is substituted by a pyridine ring-containing tertiary hydrocarbyl group.

A radiation-sensitive resin composition includes: a resin containing a structural unit A represented by formula (1); at least one radiation-sensitive acid generator selected from the group consisting of a radiation-sensitive acid generator represented by formula (2-1) and a radiation-sensitive acid generator represented formula (2-2); and a solvent. At least one R.sup.3 is an acid-dissociable group; and R.sup.41 is a hydrogen atom or a protective group to be deprotected by action of an acid. At least one of R.sup.f1 and R.sup.f2 is a fluorine atom or a fluoroalkyl group; R.sup.5a is a monovalent organic group having a cyclic structure; X.sub.1.sup.+ is a monovalent onium cation; R.sup.5b is a monovalent organic group, and X.sub.2.sup.+ is a monovalent onium cation whose atom having a positive charge is not an atom forming a cyclic structure. ##STR00001##

A resist underlayer film composition for use in a multilayer resist method, containing one or more compounds shown by formula (1), and an organic solvent,

WX).sub.n   (1)

W represents an n-valent organic group having 2 to 50 carbon atoms. X represents a monovalent organic group shown by formula (1X). “n” represents an integer of 1 to 10,

##STR00001##

The dotted line represents a bonding arm. R.sup.01 represents an acryloyl or methacryloyl group. Y represents a single bond or a carbonyl group. Z represents a monovalent organic group having 1 to 30 carbon atoms. A resist underlayer film composition can be cured by high energy beam irradiation and form a resist underlayer film having excellent filling and planarizing properties and appropriate etching resistance and optical characteristics in a fine patterning process by a multilayer resist method in the semiconductor apparatus manufacturing process.