Photoacid generating compounds, chemically amplified positive resist materials, and pattern forming method

A photoacid generating compound of General Formula (1):

• 73
• wherein R1 is an alkylene group of 2 to 8 carbon atoms;
• and R2 is a single bond, an oxygen atom, a nitrogen atom or an alkylene group of 1 to 4 carbon atoms;
• R3 is a straight-chained, branched or cyclic alkyl group of 1 to 8 carbon atoms, or an aryl group of 6 to 10 carbon atoms, and may be substituted with an alkyl group of 1 to 4 carbon atoms, a fluorinated alkyl group of 1 to 4 carbon atoms, an alkoxy group of 1 to 4 carbons, a fluorinated alkoxy group of 1 to 4 carbons atoms, a nitro group, a cyano group, a fluorine atom, a phenyl group, a substituted phenyl group, an acetyl group or a benzoyloxy group;
• either of or both of Rf1 and Rf2 are straight-chained, branched or cyclic alkyl groups, each having 1 to 20 carbon atoms containing at least one fluorine atom, and may comprise a hydroxyl group, a carbonyl group, an ester group, an ether group or an aryl group;
• when only one of Rf1 and Rf2 is the straight-chained, branched or cyclic alkyl group, having 1 to 20 carbon atoms containing at least one fluorine atom, the other thereof is a straight-chained, branched or cyclic alkyl group, having 1 to 20 carbon atoms, and may comprise a hydroxyl group, a carbonyl group, an ester group, an ether group or an aryl group;
• and Rf1 and Rf2 may be bonded together and form a ring.