Radiation-sensitive composition of chemical amplification type

A chemically amplified radiation sensitive composition comprising:

• an onium salt precursor, which generates a fluorinated alkanesulfonic acid, as a photoacid generator, wherein the alkanesulfonic acid has 4 carbon atoms, and wherein the onium salt precursor which generates a fluorinated alkanesulfonic acid is a sulfonium or iodonium salt of nonafluorobutane sulfonate, and wherein the photoacid generator is a sulfonium or iodonium salt of a fluorinated alkane sulfonic acid, represented by formula (I):
• Y+ASO3− (I)
• wherein A represents CF3CF2CF2CF2;
• and
• Y represents
• wherein R1, R2, R3, R4, and R5 each independently represent
• an alkyl group,
• a monocyclic or bicyclic alkyl group,
• a cyclic alkylcarbonyl group,
• a naphthyl group,
• an anthryl group,
• a peryl group,
• a pyryl group,
• a thienyl group,
• an aralkyl group, or
• an arylcarbonylmethylene group, or
• any two of R1, R2, and R3 or R4 and R5 together represent an alkylene or an oxyalkylene which forms a five- or six-membered ring together with the interposing sulfur or iodine, said ring being optionally condensed with aryl groups,
• one or more hydrogen atoms of R1, R2, R3, R4, and R5 being optionally substituted by one or more groups selected from the group consisting of a halogen atom, an alkyl group, a cyclic alkyl group, an alkoxy group, a cyclic alkoxy group, a dialkylamino group, a cyclic dialkylamino group, a hydroxyl group, a cyano group, a nitro group, an aryl group, an aryloxy group, an arylthio group, and groups of formulae (II) to (VI):
• wherein R6 and R7 each independently represent a hydrogen atom, an alkyl group, which may be substituted by one or more halogen atoms, or a cyclic alkyl group, which may be substituted by one or more halogen atoms, or R6 and R7 together can represent an alkylene group to form a ring,
• R8 represents an alkyl group, a cyclic alkyl group, or an aralkyl group, or R6 and R8 together represent an alkylene group which forms a ring together with the interposing —C—O— group, the carbon atom in the ring being optionally substituted by an oxygen atom,
• R9 represents an alkyl group or a cyclic alkyl group, one or two carbon atoms in the alkyl group or the cyclic alkyl group being optionally substituted by an oxygen atom, an aryl group, or an aralkyl group,
• R10 and R11 each independently represent a hydrogen atom, an alkyl group, or a cyclic alkyl group,
• R12 represents an alkyl group, a cyclic alkyl group, an aryl group, or an aralkyl group, and
• R13 represents an alkyl group, a cyclic alkyl group, an aryl group, an aralkyl group, the group —Si(R12)2R13, or the group —O—Si(R12)2R13;
• and
• a film forming hydroxystyrene based resin, wherein said film forming hydroxystyrene based resin is a polymer of 4-hydroxystyrene, 3-hydroxystyrene, or 2-hydroxystyrene, or a co-, ter-, quarter- or pentapolymer of the styrenes and other monomers, or wherein said film forming hydroxystyrene resin that is a polymer of 4hydroxystyrene, 3-hydroxystyrene, or 2-hydroxystyrene, or a co-, ter-, quarter- or pentapolymer of the styrenes and other monomers, is made alkali insoluble by protecting alkali soluble groups on the resin with an acid cleavable protecting group.