content_image/909781.jpg
With respect to the synthesis of imide and oxime sul› fonates, reference should be made to JP-A 2003-252855, U.S. Pat. No. 6,261,738, JP-A 9-95479, JP-A 9-208554, JP-A 9-230588, JP 2906999, JP-A 9-301948, JP-A 2000-314956, JP-A 2001-233842, and WO 2004/074242. 

As described above, a first embodiment of the invention provides photoacid generators suited for use in chemically amplified resist compositions which generate sulfonic acids of formula (la) upon exposure to high-energy radiation. A second embodiment provides sulfonium salts, iodonium salts, dicarboxylimide sulfonates, and oxime sulfonates serv› ing as photoacid generators in chemically amplified resist compositions. A third embodiment provides chemically amplified resist compositions comprising a photoacid gen› erator which generates a sulfonic acid of formula (1 a) upon exposure to high-energy radiation and a resin which changes its solubility in an alkaline developer liquid under the action of acid. 

Resist Composition 

The resist composition of the invention is typically embod- ied as 

(i) a chemically amplified positive resist composition com› prising 

(A) the above-mentioned photoacid generator, i.e., the photoacid generator capable of generating a sulfonic acid having formula (1 a), especially the compound of formula (2), (2a ), (2b ), (3a) or (3b ), 

(B) an organic solvent, 

(C) a base resin which changes its solubility in an alkaline developer under the action of acid, and 

one or more optional components including (D) a quencher, (E) a photoacid generator other than (A), (F) an organic acid derivative and/or fluorinated alcohol, and (G) a dissolution inhibitor having a weight average molecular weight ofup to 3,000, and further optionally, (S) a surfactant which is insoluble or substantially insoluble in water and soluble in alkaline developer and/or a surfactant which is insoluble or substantially insoluble in water and alkaline developer; and (ii) a chemically amplified negative resist composition com- prising 

(A) the above-mentioned photoacid generator, 

(B) an organic solvent, 

(C’) a base resin which is normally alkali soluble, but becomes substantially alkali insoluble under the action of a crosslinker, 

(H) a crosslinker which induces crosslinkage under the action of acid, and 

one or more optional components including (D) a quencher and (E) a photoacid generator other than (A), and further optionally, (S) a surfactant which is insoluble or substantially insoluble in water and soluble in alkaline developer and/or a surfactant which is insoluble or substantially insoluble in water and alkaline developer. 

The PAG which generates a sulfonic acid having formula (la) as component (A) is as described above. More specifi› cally, it is a compound having formula (2), (2a), (2b ), (3a) or (3b ). In the resist composition, the PAG is specifically com› pounded in an amount of0.1 to 10 parts, more specifically 1 to 7 parts by weight per 100 parts by weight of the base resin. Note that parts by weight per 100 parts by weight of the resin is often abbreviated as "phr." 

ComponentB 

The organic solvent used herein may be any organic sol› vent in which the base resin, acid generator, and other com- ponents are soluble. Illustrative, non-limiting, examples of the organic solvent include ketones such as cyclohexanone 

and methyl amyl ketone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, l-methoxy-2-propanol, and l-ethoxy-2-propanol; ethers such as propylene glycol monomethyl ether, ethylene glycol monomethyl ether, pro- pylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol mono› tert-butyl ether acetate; and lactones such as y-butyrolactone. These solvents may be used alone or in combinations of two or more thereof. Of the above organic solvents, it is recom› mended to use diethylene glycol dimethyl ether, l-ethoxy-2- propanol, PGMEA, cyclohexanone and mixtures thereof because the photoacid generator is most soluble therein. 

An appropriate amount of the organic solvent used is 200 to 3,000 parts, especially 400 to 2,000 parts by weight per 100 parts by weight of the base resin. 

ComponentC 

The base resins used as component (C) or (C’) in the inven› tive compositions include polyhydroxystyrene (PHS), and copolymers of PHS with styrene, (meth)acrylic acid esters or other polymerizable olefinic compounds, for KrF excimer laser resist use; (meth)acrylic acid ester polymers, alternating copolymers of cycloolefin with maleic anhydride and similar copolymers further containing vinyl ethers or (meth)acrylic acid esters, polynorbornene, ring-opening metathesis poly› merized cycloolefins, and hydrogenated ring-opening met› athesis polymerized cycloolefins, for ArF excimer laser resist use; and fluorinated forms of the foregoing polymers (for both KrF and ArF laser uses) for F $_{2 }$ excimer laser resist use, although the base resins are not limited to these polymers. Understandably, the sulfonium salts and iodonium salts hav› ing polymerizable substituent groups according to the inven- tion may be used as a monomer component in forming the base resin. Typical sulfonium and iodonium salts for such use are combinations of onium cations such as ( 4-acryloylox› yphenyl)diphenylsulfonium, (4-methacryloyloxyphenyl) dipheny lsulfonium, ( 4-acryloy loxypheny 1 )pheny liodonium, and ( 4-methacryloyloxyphenyl)phenyliodonium cations with anions such as 1-( difluorosulfomethyl)-2,2,2-trifluoro› ethyl hydrogen cyclohexanedicarboxylate. The base resins may be used alone or in admixture of two or more. In the case of positive resist compositions, it is a common practice to substitute acid labile groups for hydroxyl groups on phenols, carboxyl groups or fluorinated alkyl alcohols for reducing the rate of dissolution in unexposed regions. 

The base resin (C) may comprise recurring units contain- ing an acid labile group of the general formula (3) and recur› ring units of at least one type having the general formulae ( 4) to (6), shown below. 

<img src='content_image/909781.jpg'>

