Acid generator compounds are provided that are particularly useful as a photoresist composition component. In one preferred aspect, photoresists are provided that comprise (i) a polymer; (ii) a first onium salt acid generator that produces a first acid upon exposure of the photoresist composition to activating radiation; and (iii) a second onium salt acid generator that 1) comprises a covalently bound acid-labile moiety and 2) produces a second acid upon exposure of the photoresist composition to activating radiation, wherein the first acid and second acid have pKa values that differ by at least 0.5.