A process for producing a photoresist pattern comprising steps (1) to (5); (1) applying a photoresist composition onto a substrate, said photoresist composition comprising an acid generator and a resin which comprises a structural unit having an acid-liable group; (2) drying the applied composition to form a composition layer; (3) exposing the composition layer; (4) heating the exposed composition layer; and (5) developing the heated composition layer with a developer which comprises butyl acetate, wherein a distance of Hansen solubility parameters between the resin and butyl acetate is from 3.3 to 4.3, the distance is calculated from formula (1):

R=(4×(δd.sub.R−15.8).sup.2+(δp.sub.R−3.7).sup.2+(δh.sub.R−6.3).sup.2).sub.1/2   (1) in which δd.sub.R represents a dispersion parameter of the resin, δp.sub.R represents a polarity parameter of the resin, δh.sub.R represents a hydrogen bonding parameter of the resin, and R represents the distance, and a film retention ratio of the photoresist pattern relative to the composition layer is adjusted to 65% or more.

A sulfonium compound having formula (1) exerts a satisfactory acid diffusion control function wherein R.sup.1, R.sup.2 and R.sup.3 are a C.sub.1-C.sub.20 monovalent hydrocarbon group which may contain a heteroatom, p=0-5, q=0-5, and r=0-4. A resist composition comprising the sulfonium compound is processed by lithography to form a resist pattern with improved resolution, LWR, MEF and CDU.

##STR00001##

A photoresist composition comprising an acid generator and a resin which comprises one or more structural units (a1) derived from a monomer (a1) having an acid-liable group, all of monomers (a1) showing a distance of Hansen solubility parameters between the monomer (a1) and butyl acetate in the range of 3 to 5, the distance being calculated from formula (1):

R=(4×(δd.sub.m−15.8).sup.2+(δp.sub.m−3.7).sup.2+(δh.sub.m−6.3).sup.2).sup.1/2  (1)

in which δd.sub.m represents a dispersion parameter of a monomer, δp.sub.m represents a polarity parameter of a monomer, δh.sub.m represents a hydrogen bonding parameter of a monomer, and R represents a distance of Hansen solubility parameters, and at least one of the monomers (a1) showing a difference of R between the monomer (a1) and a compound in which an acid is removed from the monomer (a1) in the range of not less than 5.

A polymer comprising recurring units derived from a sulfonium salt of specific structure having a polymerizable group is coated to form a resist film which is amenable to precise micropatterning because of improved LWR, CDU and resolution.

Chain scission resist compositions suitable for EUV lithography applications may include monomer functional groups that improve the kinetics and/or thermodynamics of the scission mechanism. Chain scission resists may include monomer functional groups that reduce the risk that leaving groups generated through the scission mechanism may chemically corrode processing equipment.

A salt represented by formula (I): ##STR00001##
wherein Q.sup.1 and Q.sup.2 independently represent a fluorine atom or a C.sub.1 to C.sub.6 perfluoroalkyl group, R.sup.1 and R.sup.2 each independently represent a hydrogen atom, a fluorine atom or a C.sub.1 to C.sub.6 perfluoroalkyl group, z represents an integer of 0 to 6, R.sup.3 represents a hydrogen atom, a fluorine atom, a C.sub.1 to C.sub.12 alkyl group or a C.sub.1 to C.sub.12 fluorinated alkyl group, R.sup.4 represents a C.sub.1 to C.sub.12 fluorinated alkyl group, L.sup.2 represents a single bond, a C.sub.1 to C.sub.12 divalent saturated hydrocarbon group, etc., R.sup.5 represents a hydrogen atom, a halogen atom or a C.sub.1 to C.sub.6 alkyl group that may have a halogen atom, L.sup.1 represents a group represented by formula (b1-1), etc., * represents a bonding site to —CR.sup.3R.sup.4; L.sup.b2 and L.sup.b3 each independently represent a single bond or a C.sub.1 to C.sub.22 divalent saturated hydrocarbon group; Z.sup.+ represents an organic cation.

A positive resist composition comprising a polymer comprising recurring units having both an acyl or alkoxycarbonyl group and an acid labile group-substituted hydroxyl group exhibits a high contrast of alkaline dissolution rate before and after exposure, a high resolution, a good pattern profile and minimal edge roughness.

A carboxylic acid onium salt of formula (1) exerts a satisfactory acid diffusion control (or quencher) function. A resist composition comprising the carboxylic acid onium salt can be processed by DUV or EUV lithography to form a resist pattern with improved resolution, reduced LWR and minimal defects after development.

##STR00001##

The present application relates to a block copolymer and its use. The present application can provides a block copolymer that has an excellent self assembling property or phase separation property and therefore can be used in various applications and its use.

The present invention provides a novel photopolymer formulation comprising matrix polymers, writing monomer and a photoinitiator and further comprising a compound of formula (1) ##STR00001##
where A.sup.1, A.sup.2 and A.sup.3 are each independently hydrogen, fluorine, chlorine, bromine or iodine, R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are each independently hydrogen, halogen, cyano, nitro, amino, alkylimino, azide, isonitrile, enamino, formyl, acyl, carboxyl, carboxylate, carboxamide, orthoester, sulphonate, phosphate, organosulphonyl, organosulphoxidyl, optionally fluorinated alkoxy or an optionally substituted aromatic, heteroaromatic, aliphatic, araliphatic, olefinic or acetylenic radical while suitable radicals may be connected together via bridge of any desired substitution, or in that two or more compounds of formula (I) may be connected together via at least one of the radicals R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5, in which case these radicals therein constitute a 2- to 4-tuply functional bridge, with the proviso that at least one of the radicals R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 is not hydrogen. Further subjects of the invention are a photopolymer comprising matrix polymers, a writing monomer and photoinitiator, a holographic medium comprising a photopolymer formulation of the present invention or being obtainable by use thereof, the use of a holographic medium of the present invention and also a process for producing a holographic medium by using a photopolymer formulation of the present invention.