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(In the formulae, Rxyl represents a hydrogen atom or a methyl group.) 

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The alicyclic hydrocarbon-based acid-decomposable resin for use in the present invention can be synthesized by an ordinary method (for example, radical polymerization). Examples of the general synthesis method include a batch polymerization method of dissolving monomer species and 

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(ARL-6) 

(ARL-7) 

ARH-1 30 

ARH-2 

ARH-3 

an initiator in a solvent and heating the solution, thereby carrying out the polymerization, and a dropwise-addition polymerization method of adding dropwise a solution con› taining monomer species and an initiator to a heated solvent for 1 to 10 hours, with the dropwise-addition polymerization method being preferable. Examples of the reaction solvent include ethers such as tetrahydrofuran, 1,4-dioxane, and diisopropyl ether; ketones such as methyl ethyl ketone and methyl isobutyl ketone; ester solvents such as ethyl acetate, amide solvents such as dimethyl formamide and dimethyl acetamide; and solvents which dissolve the composition of the present invention, such as propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, and cyclohexanone. It is more preferable to carry out polymer› ization using the same solvent as the solvent used in the actinic ray-sensitive or radiation-sensitive resin composition of the present invention. Thus, generation of the particles during storage can be suppressed. 

It is preferable that the polymerization reaction is carried out in an inert gas atmosphere such as nitrogen and argon. As the polymerization initiator, commercially available radi› cal initiators ( azo-based initiators, peroxides, or the like) are used to initiate the polymerization. As the radical initiator, an azo-based initiator is preferable, and the azo-based ini› tiator having an ester group, a cyano group, or a carboxyl group is preferable. Preferred examples of the initiators include azobisisobutyronitrile, azobisdimethylvaleronitrile, and dimethyl 2,2’-azobis(2-methyl propionate). The initiator is added or added in portionwise, depending on the pur› poses, and after completion of the reaction, the reaction mixture is poured into a solvent, and then a desired polymer is recovered by a method such as powder and solid recovery. The concentration of the reactant is 5% to 50% by mass, and preferably 10% to 30% by mass. The reaction temperature is usually 10° C. to 150° C., preferably 30° C. to 120° C., and more preferably 60° C. to 100° C. 

For the purification, the same method as for a resin (C) which will be described later can be used, and an ordinary method such as a liquid-liquid extraction method of apply› ing water washing or combining it with an appropriate solvent to remove the residual monomers or oligomer com› ponents; a purification method in a solution state, such as ultrafiltration of extracting and removing only the polymers having a molecular weight no more than a specific molecular weight; a re-precipitation method of dropwise adding a resin solution into a poor solvent to solidify the resin in the poor solvent, thereby removing the residual monomers and the like: and a purification method in a solid state, such as cleaning of a resin slurry with a poor solvent after separation of the slurry by filtration can be applied. 

The weight-average molecular weight of the resin accord› ing to the present invention is a value in terms of polystyrene by means of a GPC method, and is preferably 1,000 to 200,000, more preferably 1,000 to 20,000, and still more preferably 1,000 to 15,000. By setting the weight-average molecular weight to 1,000 to 200,000, the heat resistance and the dry etching resistance can be prevented from being deteriorated, and the film forming properties can be pre- vented from being deteriorated due to deteriorated develop› ability or increased viscosity. 

The resin having a dispersity (molecular weight distribu› tion) in a range of usually 1 to 5, preferably 1 to 3, more preferably 1.2 to 3.0, and particularly preferably 1.2 to 2.0 is used. As the dispersity is smaller, the resolution and the resist shape are excellent, the side wall of the resist pattern is smooth, and the roughness is excellent. 

