Positive-working radiation-sensitive mixture

A process for producing a solution of a basic or non-basic sulfonium compound (A) comprising formula II:

• ›SR.sup.5 R.sup.6 R.sup.7 !.sup.+ X.sub.2.sup.- II
• wherein
• R.sup.5, R.sup.6 and R.sup.7 each independently represent a C.sub.1 -C.sub.18 alkyl, aryl or heteroaryl group or an aryl group mono-, di- or tri-substituted with an alkyl, an alkylaryl, an aryl, a halogen, an alkoxy, a phenoxy, a thiophenol, a phenylsulfonyl or a phenylsulphenyl, with the proviso that at least one of R.sup.5, R.sup.6 or R.sup.7 comprise an aryl group;
• and
• X.sub.2.sup.- represents a basic anion having a pK.sub.B value of -3 to +5;
• said process comprising the steps of:
• (a) dissolving a sulfonium salt (B) in a metal-ion free polar or non-polar solvent to form a solution, said sulfonium salt (B) comprising said formula II, wherein R.sup.5 to R.sup.7 of said sulfonium salt (B) have the same meaning as above and X.sub.2.sup.- represents a non-nucleophilic anion;
• (b) contacting said solution for a sufficient amount of time with a basic ion-exchange resin having a quaternary ammonium group to replace the anion of (B) with a hydroxide ion and to form a sulfonium hydroxide solution;
• (c) separating said sulfonium hydroxide solution from the resin;
• and
• (d) adding an active hydrogen containing compound or its base-labile precursor to said sulfonium hydroxide solution to yield a solution of the sulfonium compound (A) wherein X.sub.2.sup.- represents a basic anion other than a hydroxy ion.

A process for producing a solution for use as resist material that is sensitive to active beam irradiation of a basic or non-basic sulfonium compound (A) of formulae II-V:

• ##STR6## wherein, R.sup.5, R.sup.6 and R.sup.7 each independently represent a C.sub.1 -C.sub.18 alkyl, aryl or heteroaryl group or an aryl group mono-, di- or tri-substituted with an alkyl, an alkylaryl, an aryl, a halogen, an alkoxy, a phenoxy, a thiophenol, a phenylsulfonyl or a phenylsulphenyl, with the proviso that at least one of R.sup.5, R.sup.6 or R.sup.7 comprise an aryl group;
• Y represents (CH.sub.2).sub.n (wherein n is 0 or 1), O or S;
• R.sup.8 and R.sup.9 represent a C.sub.1 -C.sub.4 alkyl, alkoxy or a halogen;
• R.sup.10 and R.sup.11 represent a C.sub.1 -C.sub.4 alkyl, alkoxy or a halogen;
• n is 5 or 6;
• and
• X.sub.2.sup.- represents a basic anion having a pK.sub.B value of -3 to +5;
• comprising the steps of:
• (a) dissolving a sulfonium salt (B) in a metal-ion free polar or non-polar solvent to form a solution, said sulfonium salt (B) being selected from said formulae II-V, wherein R.sup.5 to R.sup.11, Y and n of said sulfonium salt (B) have the same meaning as above and X.sub.2.sup.- represents a non-nucleophilic anion;
• (b) contacting said solution for a sufficient amount of time with a basic ion-exchange resin having a quaternary ammonium group to replace the anion of (B) with a hydroxide ion and to form a sulfonium hydroxide solution;
• (c) separating said sulfonium hydroxide solution from the resin;
• and optionally
• (d) adding an active hydrogen containing compound or its base-labile precursor to said sulfonium hydroxide solution to yield a solution of the sulfonium compound (A) wherein X.sub.2.sup.- represents a basic anion other than a hydroxy ion.