CA2280365A1 - Sulfonyloximes for i-line photoresists of high sensitivity and high resist thickness - Google Patents

Abstract

Composition which can be activated by light, comprising at least one compound which may be crosslinked by the action of an acid and/or at least one compound which changes its solubility under the action of an acid, and as photoinitiator at least one compound generating a sulfonic acid under the exposure of light of a wavelength of 240 to 390 nm and having a molar extinction coefficient .epsilon. below 10 at i-line (365 nm) are especially suitable for the preparation of negative and positive photoresists, printing plates, image recording materials or colour filters.

Description

A-21814/A/CGJ 110 CA 02280365 1999-os-i6 Sulfonyloximes for i-line photoresists of high sensitivity and high resist thickness The present invention relates to compositions comprising latent acid compounds, to the use of these compounds as photo-sensitive acid generator, particularly in chemically amplified photoresists, in printing plates, colour filters or image recording materials which are develop-able in alkaline medium, to their use as dissolution inhibitors in a corresponding positive photoresist, and to a process for the production of images using such resists, printing plates or image recording materials.
A chemically amplified photoresist will be understood as meaning a resist composition, the photosensitive component of which, when irradiated, generates only that amount of acid which is required to catalyse a chemical reaction of at least one acid-sensitive component of the resist, as a result of which the ultimate differences in solubility between irradiated and non-irradiated areas of the photoresist first develop.
Industrial paint formulations based on a large number of photosensitive oxime sulfonates and conventional acid-curable resins are disclosed in US 4540598. These formulations are cured firstly with actinic light, especially with radiation in the range of 250 to 400 nanome-ters. The oxime sulfonates generate acid, so that a thermal cure in which the material also becomes insoluble in customary solvents is able to take place even at quite low temperatur-es. Nothing can be inferred about an imagewise exposure of corresponding resist films or about related problems as well as the image properties of the numerous formulations falling within the generic scope of the teaching of this patent specification.
Oxime sulfonates, which are sparingly soluble in alkaline-aqueous developers, can be con-verted to the soluble form of the free acid by irradiation. Combined with a suitable film-form-ing resin, they can therefore be used as dissolution inhibitors for the production of positive resists.
Conventional positive photoresist compositions based on oxime sulfonates and alkali-soluble binders, typically cresol novolaks or hydroxymethacrylate/acrylic acid copolymers, are also known and are disclosed in EP 0241423. According to this reference, radiation of 200 to 600 nm can be used for exposing the resists. The shortcoming of these photoresists is, however, that resolution and sensitivity are simultaneously never altogether satisfactory. This is par-ticularly the case upon exposure to radiation in the range of the mercury i-line, which has a wavelength of 365 nanometers and is often used for the imagewise exposure of resist films, because mercury medium- and high-pressure lamps are inexpensive sources of radiation for producing radiation of these wavelengths with good intensity.
Accordingly, there is clearly a need for reactive nonionic latent acid generators which are thermally and chemically stable and which, after being activated by light, in particular by radi-ation having the wavelength of the mercury i-line (365nm), can be used as catalysts for dif-ferent acid-catalysed reactions, such as polycondensation reactions, acid-catalysed depoly-merisation reactions, acid-catalysed electrophilic substitution reactions or the acid-catalysed removal of protective groups. There is, in particular, a need for acid generators which can be activated by light and with which systems of higher thickness can be exposed in a way that at the same time high sensitivity and a good shape of the form of the resist profiles can be maintained. Such a high thickness is e.g. of advantage for ion-implantation processes where constantly increasing ion-doses require thicker layers to resist to the ion bombar-dment. There are additionally other application-areas where thick resist layers are required for simple geometrical reasons like for example the manufacturing of magnetic heads for the hard-disks for storage media. High thermal stability to obtain a high resistance against the treatment with ions during ion-implantation processes which are commonly used during manufacturing of semiconductor devices is an additional desirable property.
US 5627011 discloses the use of oxime sulfonate compounds in high-resolution i-line photo-resists of high sensitivity. This publication mentions oxime sulfonate compounds which can generate aromatic sulfonic acids.
EP 780729 and WO 98/10335 disclose chemically amplified resist compositions comprising oxime-sulfonate compounds with alkyl- instead of aromatic sulfonic acid groups.
JP 9-292704 discloses that resist properties are further improved if oxime-sulfonate com-pounds with short alkyl-sulfonic acid groups (C1-C4) are used having a molar extinction co-efficient ~ < 100 at i-line (365 nm).
The present invention provides photoresist compositions having excellent resist profiles while at the same time maintaining excellent sensitivity even at a thickness of resist layers going well beyond the typical range of 1-2 micron. These properties are observed especially when the resist compositions are exposed to radiation in the range of the mercury i-line which has a wavelength of about 365 nanometers.
Surprisingly, excellent profiles and at the same time good sensitivity are obtained with che-mically amplified photoresist compositions which are developable in aqueous-alkaline media and having a resist thickness larger than 2 pm by using photoacid generators which have a molar extinction coefficient ~ below 10. This applies both to negative as well as to positive photoresists containing an acid-sensitive component that undergoes an acid-catalysed che-mical reaction which changes the solubility of the compositons in aqueous-alkaline deve-lopers.
Accordingly, this invention relates to compositions which can be activated by light, comprising (a) at least one compound which may be crosslinked by the action of an acid and/or (b) at least one compound which changes its solubility under the action of an acid, and (c) as photoinitiator at least one compound generating an acid under the exposure of light of a wavelength of 240 to 390 nm and having a molar extinction coefficient c below 10 at i-line (365 nm).
In particular, the compound (c) is a compound generating a sulfonic acid.
Preferred are compositions having a thickness larger than 2 pm when coated onto a substrate.
The invention further relates to composition as described above, comprising as component (c) a compound comprising a structural unit of formula I
c=N-o-sot- (I), and wherein the compounds are characterized by a molar extinction coefficient a below 10 at 365 nm.
Preferred compositions are such, comprising as component (c) a compound of formula la NC
R~
C=N-O-S02-R6 w R2 ' (la) , wherein RS

Ra R,, R2, R3, R4 and R5 independently of one another are hydrogen, unsubstituted or halogen-substituted C,-C,2alkyl; or R,, R2, R3, R4 and R5 are halogen;
R6 is unsubstituted or halogen-substituted C,-C,ealkyl, phenyl-C,-C3alkyl, camphoryl, phenyl, naphthyl, anthracyl or phenanthryl, the radicals phenyl, naphthyl, anthracyl and phenanthryl being unsubstituted or substituted by one or more of the radicals halogen, C,-C4haloalkyl, CN, N02, C,-C,salkyl, phenyl, OR,o, COORS, -O(CO)-C,-C4alkyl, and/or by NR,Re;
R, and Ra independently of each other are hydrogen or C,-C,2alkyl, which is unsubstituted or substituted by OH, C,-C4alkoxy, C,-C,2alkylsulfonyl, phenylsulfonyl, (4-methylphenyl)-sulfonyl and/or by C,-Csalkanoyl; or R, and Re are C2-C,2alkyl, which is interrupted by -O- and which is unsubstituted or substituted by OH, C,-C4alkoxy, C,-C,2alkylsulfonyl, phenylsulfonyl, (4-methylphenyl)sulfonyl and/or by C,-Csalkanoyl; or R, and R8 are phenyl, C2-Csalkanoyl, benzoyl, C,-Csalkylsulfonyl, phenylsulfonyl, (4-methylphenyl)-sulfonyl, naphthylsulfonyl, anthracylsulfonyl or phenanthrylsulfonyl; or R, and Re, together with the nitrogen atom to which they are linked, form a 5-, 6- or 7-membered ring which may be interrupted by -O- or by -NR"-;
R9 is C,-C,2alkyl which is unsubstituted or substituted by OH and/or by C,-C4alkoxy, or R9 is C2-C,2alkyl which is interrupted by -O- and which is unsubstituted or substituted by OH
and/or by C,-C4alkoxy;
R,o is hydrogen; C,-C,2alkyl which is unsubstituted or substituted by phenyl, OH, C,-C,2-alkoxy, C,-C,2alkylsulfonyl, phenylsulfonyl, (4-methylphenyl)sulfonyl and/or by C2-C6-alkanoyl; or R,o is C2-C,2alkyl which is interrupted by -O- and which is unsubstituted or substituted by phenyl, OH, C,-C,2alkoxy, C,-C,2alkylsulfonyl, phenylsulfonyl, (4-methyl-phenyl)sulfonyl and/or by C2-Csalkanoyl; or R,o is phenyl;
R" is hydrogen, unsubstituted or OH-substituted C,-C,2alkyl, or C2-C,2alkyl which is interrupted by -O-;
and wherein the compounds of formula la are characterized by a molar extinction coefficient ~ below 10 at 365 nm.

According to this invention it is also possible to use mixtures of isomeric forms (cis-trans iso-mers, E/Z- or syn/anti-isomers) of the oxime sulfonates of formula la.
C,-C,Salkyl is linear or branched and is, for example, C,-C,6-, C,-C,4-, C,-C,2-, C,-C8-, C,-C6-or C,-C4alkyl. Examples are methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, 2,4,4-trimethylpentyl, 2-ethylhexyl, octyl, nonyl, decyl, dodecyl, te-tradecyl, pentadecyl, hexadecyl and octadecyl.
C,-C,salkyl, C,-C,zalkyl and C,-C4alkyl have the same meanings as given above for C,-C,BaI-kyl up to the corresponding number of C-atoms.
Halogen is fluorine, chlorine, bromine and iodine, especially fluorine, chlorine and bromine, preferably fluorine and chlorine.
Halogen-substituted C,-C,Balkyl or halogen-substituted C,-C,2alkyl are alkyl radicals as des-cribed above, which have one or more than one same or different halogen atoms as substi-tuents. There are for example 1 to 3 or 1 or 2 halogen substituents on the alkyl radical. The halogen atoms are situated either at the same carbon atom, but may also be positioned at different C-atoms of the alkyl radicals. Examples are fluoromethyl, chloromethyl, bromome-thyl, trifluoromethyl, 1-chlorethyl, 2-chlorethyl and the like.
C,-C4haloalkyl corresponds to C,-C4alkyl which is substituted by halogen. The same expla-nations as given above apply for these radicals, up to the corresponding number of C-atoms.
C2-C,2alkyl, which is interrupted by -O-, is linear or branched and is for example, interrupted 1-6 times, for example 1-3 times or once or twice by -O-. The O-atoms in the alkyl chain are positioned non-successive. This produces structural units such as, for example, -CH2-O-CH2-, -CH2CH2-O-CH2CH2-, -[CH2CH20]y , -(CHZCH20]Z CH2-, where y = 1-6 and z = 1-5, -(CH2CH20)5CH2CH2-, -CH2-CH(CH3)-O-CH2-CH(CH3)- or -CH2-CH(CH3)-O-CH2-CH2CH2-.
C,-C,2AIkoxy is a linear or branched radical and is C,-C8-, C,-C6-, C,-C4alkoxy, for example, methoxy, ethoxy, propoxy, isopropoxy, n-butyloxy, sec-butyloxy, isobutyloxy, tert-butyloxy, pentyloxy, hexyloxy, heptyloxy, 2,4,4-trimethylpentyloxy, 2-ethylhexyloxy, octyloxy, nonyloxy, decyloxy or dodecyloxy, especially methoxy, ethoxy, propoxy, isopropoxy, n-butyloxy, s-butyloxy, iso-butyloxy or tert-butyloxy, preferably methoxy.
C,-C4alkoxy has the same meanings as given above up to the corresponding number of C-atoms.
C,-C,2alkylsulfonyl means C,-C~2alkyl-O-S02-, wherein the C,-C,2alkyl radicals are defined as described above.
C,-Csalkanoyl is linear or branched and is, for example, C~-C4alkanoyl.
Examples are form-yl, acetyl, propionyl, butanoyl, isobutanoyl, pentanoyl or hexanoyl, preferably acetyl.
Phenyl-C,-C3alkyl is for example benzyl, phenylethyl, a-methylbenzyl or a,a-dimethylbenzyl, especially benzyl.
Substituted radicals phenyl, naphthyl, anthracyl and phenanthryl are substituted one to four times, for example once, twice or three times, especially once or twice.
Substituents on the phenyl ring are in 2-position; 2,4-position; 2,6-position; 3-position; 3,5-position; 4-position; or 6-position, especially in 2-position, 3-position, 4-position or 6-position of the phenyl ring.
If R, and R8, together with the nitrogen atom to which they are linked, form a 5-, 6- or 7-mem-bered ring which may be interrupted by -O- or by -NR11-, saturated or unsaturated rings are formed, for example aziridin, pyrrol, pyrrolidin, oxazol, pyridin, 1,3-diazin, 1,2-diazin, piperidin or morpholin.
The terms "and/or" or "or/and" in the claims and in then specification are meant to express that not only one of the defined alternatives (substituents) may be present, but also several of the defined alternatives (substituents) together, namely mixtures of different alternatives (sub-stituents).
The term "at least" is meant to define one or more than one.
The molar extinction coefficient ~ of the acid-generating compounds which are suitable for the compositions according to the present invention is below 10 at 365 nm (mercury I-line).
The coefficient ~ is part of the l.ambert Beer equation, which is familiar to the person skilled _7_ in the art. This coefficient is determined from the UV-absorption-spectra of the compounds, which are measured in common organic solvents, like acetonitrile or tetrahydrofuran (THF) Since ~-values are slightly shifting depending on the solvent used to measure the UV-spectrum all values related to this invention refer to THF as solvent.
Generally any compound generating an acid upon irradiation and having a molar extinction coefficient ~ below 10 is suitable for the compositions according to the present invention, or the claimed photoresists respectively. Suitable are for example compounds generating Lew-is acids as well as compounds generating Bronsted acids, for example compounds generat-ing carboxylic acids, sulfonic acids, phosphonic acids, PFs , BF4 , SbFS and the like.
Examples of such compounds are sulfonium- and iodonium salts as well as derivatives of nitrobenzylsulfonates and bis-sulfonyl diazo urethanes.
Preferably compounds generating sulfonic acids, such as oxime sulfonate compounds are used in the claimed compositions.
In particular, the oxime sulfonate compounds which are suitable as acid generators in the compositions according to the invention are compounds of formula la, having a molar extinc-tion coefficient a below 10, wherein R,, R2, R3, R4 and R5 independently of one another are hydrogen, C,-Caalkyl, halogen, or C,-C4haloalkyl; and R6 is C~-ClBalkyl, phenyl-C,-C3alkyl, camphoryl, C~-C~ohaloalkyl, phenyl, naphthyl, anthracyl or phenanthryl, wherein the radicals phenyl, naphthyl, anthracyl and phenanthryl are unsub-stituted or substituted by one or more of the radicals halogen, C,-C4haloalkyl, CN, N02, C,-C,salkyl, phenyl, OR,o; and R,o is defined as above.
The compositions preferably comprise compounds of formula la, having a molar extinction coefficient a below 10, wherein R, ,R2, R3, R4 and R5 independently of one another are hydrogen, C,-C4alkyl, halogen, or C,-C4haloalkyl, with the proviso that at least two of the radicals R,, R2, R3, R4 or R5 are hydro-gen; and R6 is C,-C,2alkyl, phenyl-C,-C3alkyl, camphoryl, C,-C4haloalkyl, or phenyl, wherein the phenyl radical is unsubstituted or substituted by one or more halogen, C,-C4haloalkyl, N02, C,-C8al-kyl, phenyl or OR,o; and _g_ R,o is C,-C,2alkyl.
Examples of latent sulfonic acids of formula la are the methanesulfonates, butanesulfonates, benzenesulfonates, 4-methylphenylsulfonates, 4-methoxybenzenesulfonates and 10-camphorsulfonates of a-hydroxyimino-4-methylbenzylcyanide, a-hydroxyimino-4-butylbenzylcyanide, a-hydroxyimino-3-methylbenzylcyanide, a-hydroxyimino-2-methylbenzylcyanide, a-hydroxyimino-2,4-dimethylbenzylcyanide, a-hydroxyimino-3,4-dimethylbenzylcyanide, a-hydroxyimino-3,4-dibutylbenzylcyanide, a-hydroxyimino-2,4,6-trimethylbenzylcyanide, a-hydroxyimino-2-chlorobenzylcyanide , a-hydroxyimino-2,4-dichlorobenzylcyanide, a-hydroxyimino-4-chlorobenzylcyanide, a-hydroxyimino-4-fluorobenzylcyanide.
The oxime sulfonates of formula I or la, respectively, are prepared by methods described in the literature, e.g. by reacting suitable free oximes of formula 2 with sulfonic acid halides of formula 3 in the presence of a base such as triethylamine, or by reacting the salt of an oxime with a sulfonic acid chloride.
These methods have been published, for example, in EP 48615.
NC NC O
I I
~C=N-OH + CI-S02-R6 '~ C=N-O-S-R6 R R' I I
O
(2) (3) (la) R2 R, wherein R is R3 ~ ~ and R,, R2, R3, R4, R5 and R6 are as defined above.
Ra Rs _g_ The reaction is conveniently carried out in an inert organic solvent in the presence of a terti-ary amine.
The sodium salts of the oximes are obtained, for example, by reacting the corresponding ox-ime with a sodium alcoholate in dimethylformamide (DMF) The oxime sulfonates are obtained in the syn- (E, cis) or anti- (Z, trans) form or also as mix-tures of the two conformers. According to this invention it is possible to use single confor-mers as well as any mixture of different conformers.
If a single conformer is needed, it is obtained from the mixture through customary methods, known by the person skilled in the art, as, for example crystallisation, destillation or chroma-tography.
The oximes (2) required for the reaction are prepared in general analogy to known methods, for example by reacting compounds containing reactive methylene groups, such as benzyl-cyanide derivatives or phenylacetic acid derivates, with an alkyl nitrite, e.g. methyl nitrite or isoamyl nitrite, and a sodium alcoholate, e.g. sodium methanolate. Such reactions are des-cribed, inter alia, in "The systematic identification of organic compounds", John Wiley and Sons, New York, 1980, p. 181, in "Die Makromolekulare Chemie", 1967, 108, 170, or in "Or-ganic Synthesis", 1979, 59, 95.
Oximes can also be obtained e.g. by reacting a corresponding carbonyl compound or thio-carbonyl compound with hydroxylamine.
A further preparation method is nitrosation of hydroxyaromatics.
The preparation of sulfonic acid halides (3) is known to the person skilled in the art and is described, for example, in the standard chemistry textbooks.
It is an object of this invention to provide photoresists comprising compounds generating an acid upon irradiation, which compounds have a molar extinction coefficient a below 10 at 365 nm. Accordingly, subject of the invention is a chemically amplified photoresist, which is sen-sitive to radiation in the range from 340 to 390 nm, comprising a photosensitive acid genera-tor, characterized by a molar extinction coefficient ~ below 10 at 365 nm.

It is a further object of this invention to provide photoresists comprising compounds of formula I or la. Accordingly, subject of the invention is a chemically amplified photoresist, which is sensitive to radiation in the range from 340 to 390 nm, comprising a photosensitive acid generator of formula I, as defined above, characterized by a molar extinction coefficient ~ below 10 at 365 nm. as well as a chemically amplified photoresist, which is sensitive to radiation in the range from 340 to 390 nm, comprising a photosensitive acid generator of for-mula la, as defined above, characterized by a molar extinction coefficient ~
below 10 at 365 nm.
These chemically amplified photoresists preferably have a thickness of more than 2 pm.
Also the compositions according to the invention preferably are applied in a thickness of more than 2 ~m befor the irradiation.
These resists encompass chemically amplified, negative photoresists which are developable in alkaline medium and having a resist thickness larger than 2 pm and are sensitive to radia-tion in the range from 340 to 390 nanometers, which resists are based on photosensitive acid generator having a a molar extinction coefficient E below 10 at 365 nm.
These resists encompass further in particular chemically amplified, negative photoresists which are developable in alkaline medium and having a resist thickness larger than 2 pm and are sensitive to radiation in the range from 340 to 390 nanometers, which resists are based on oxime sulfonates as defined above as photosensitive acid generator.
Another embodiment of the invention relates to chemically amplified, positive photoresists which are developable in alkaline medium and having a resist thickness larger than 2 pm and are sensitive to radiation in the range from 340 to 390 nanometers, which resists are based on oxime sulfonates as defined above as photosensitive acid.
Both embodiments of the photoresists according to the invention are readily able to resolve structural units having dimensions in the submicron range, the radiation used being in the range of 340 to 390 nanometers. The resist structures remaining on the substrate after de-velopment exhibit very good steepness of the side walls. Despite the extremely low optical absorption the resists further have excellent sensitivity to the given radiation. This feature is especially unexpected, as the oxime sulfonates chosen as acid generators absorb radiation of this wavelength only to an extremely low extent. In addition, particularly the negative resists, have the additional advantage of showing improved thermal resistance being favorable for ion-implantation processes.
The present invention also pertains to the use of compounds of formula I or la, having a mo-lar extinction coefficient a below 10, as photoacid generators in compositions comprising compounds which can be crosslinked by the action of an acid or/and as dissolution inhibitors for compounds which change their solubility under the action of an acid, where the irradiation is carried out, for example, imagewise, as well as a process for generating acids, wherein a photoacid generator of formula I or la, having a molar extinction coefficient E below 10, is irradiated with light in a wavelength range from 340-390 nm.
In photocurable compositions, oximesulfonic acid esters act as latent curing catalysts: when irradiated with light they generate acid which catalyses the crosslinking reaction. In addition, the acid generated by the radiation can, for example, catalyse the removal of suitable acid-sensitive protective groups from a polymer structure, or the cleavage of polymers containing acid-sensitive groups in the polymer backbone. Other applications are, for example, colour-change systems based on a change in the pH or in the solubility of, for example, a pigment protected by acid-sensitive protective groups. Compositions using pH sensitive dyes or latent pigments in combination with oxime sulfonates can be used as light indicators or sim-ple throw away dosimeters. Especially for light, that is invisible to the human eye, like UV- or IR-light, such dosimeters are of interest.
The oxime-sulfonates of the present invention can also be used to shape polymers that un-dergo an acid induced transition into a state where they have the required properties using photolithography. For instance, the oxime-sulfonates can be used to pattern conjugated emissive polymers as described in M.L. Renak; C. Bazan; D. Roitman; Advanced materials 1997, 9, 392. Such patterned emissive polymers can be used to manufacture microscalar patterned Light Emitting Diodes (LED) which can be used to manufacture displays and data storage media. In a similar way precursors for polyimides (e.g. polyimide precursors with a-cid labile protecting groups which change the solubility during development) can be irradiat-ed to form patterned polyimide layers that can serve as protective coating, insulating layers and buffer layers in the production of microchips and printed circuit boards.
It is known from literature that conjugated polymers like, e.g. polyanilines can be converted from the semiconductive to the conductive state by means of proton doping. The oxime-sul-fonates of the present invention can also be used as acid generators to imagewise irradiate such conjugated polymers in order to make such a conversion selectively in the exposed ar-eas.
Oximesulfonic acid esters that are sparingly soluble in an aqueous-alkaline developer can be rendered soluble in the developer by means of light-induced conversion into the free acid, with the result that they are used as dissolution inhibitors in combination with suitable film-forming resins.
Resins that can be crosslinked by acid catalysis are, for example, mixtures of polyfunctional alcohols or hydroxy-group-containing acrylic and polyester resins, or partially hydrolysed po-lyvinyl acetals or polyvinyl alcohols with polyfunctional acetal derivatives.
Under certain con-ditions, for example the acid-catalysed self-condensation of acetal-functionalised resins is also possible.
In addition, oxime sulfonates are used e.g. as hardeners, which can be activated by light, for siloxane group-containing resins. These resins can, for example, either undergo self-con-densation by means of acid-catalysed hydrolysis or be crosslinked with a second component of the resin, such as a polyfunctional alcohol, a hydroxy-group-containing acrylic or polyester resin, a partially hydrolysed polyvinyl acetal or a polyvinyl alcohol. This type of polycon-densation of polysiloxanes is described, for example, in J.J. Lebrun, H. Pode, Comprehen-sive Polymer Science, Volume 5, page 593, Pergamon Press, Oxford, 1989.
It is evident, that the acid-initiated reactions as decribed above in the context of the present invention can not only be performed with oxime sulfonate compounds as acid generating agents, but also with other acid generating compounds having a molar extinction coefficient E below 10. Examples of such compounds are listed above.
As already mentioned above, the difference in solubility between irradiated and non-irradia-ted sections that occurs as a result of the acid-catalysed reaction of the resist material dur-ing or after irradiation of the resist may be of two types depending on which further constitu-ents are present in the formulation, or the resist. If the compositions according to the inven-tion comprise components that increase the solubility of the composition in the developer, the resist is positive. If, on the other hand, these components reduce the solubility of the composition, the resist is negative.

Acid-sensitive components that produce a negative resist are in particular compounds that, when catalysed by acid (e.g. the acid formed during irradiation of the compound of formula I
or la, respectively), are capable of undergoing a crosslinking reaction with themselves or with one or more further components of the composition. Compounds of this type are, for example, the known acid-curable resins, such as, for example, acrylic, polyester, alkyd, melamine, urea, epoxy and phenolic resins, or mixtures thereof. Amino resins, phenolic resins and epoxy resins are very suitable. Acid-curable resins of this type are generally known and are described, for example, in Ullmann's Encyclopadie der technischen Chemie, 4th Edition, Vol. 15 (1978), p. 613 - 628. The resins generally are present in a concentration of 2 to 40% by weight, preferably of 5 to 30% by weight, based on the total solids content of the negative resist composition.
Particularly preferred as acid-curable resins are amino resins, such as non-etherified or eth-erified melamine, urea, guanidine or biuret resins, preferably methylated melamine resins or butylated melamine resins, corresponding glycolurils and urones. Resins are understood in this context to be the customary technical mixtures, which usually also comprise oligomers, as well as pure and high purity compounds. N-methoxymethyl melamine (formula 7) and te-tramethoxymethyl glucoril (formula 8) and N,N'-dimethoxymethylurone (formula 9) are the acid-curable resins given the greatest preference in the context of the present application.
N -(CH20CH3)Z CH30CH2 CH20CH3 I
N ~ N (7)~ O ~N ~ N~ O (8)~
N N
(CH30CH2)2 N N N -(CH20CH3)2 O
CH30CH2 ~ , CH20CH3 N~N
(9).
O
The concentration of the acid generating compound in general and specifically the concen-tration of the compound of formula I or la, respectively, in negative resists is typically from 0.1 to 30 % by weight, preferably 0.1 to 20 % by weight, based on the total solids content of the composition. A concentration from 1 to 15 % by weight is particularly preferred.

Where appropriate, the negative compositions may additionally comprise a film-forming poly-meric binder. This binder is preferably an alkali-soluble phenolic resin. Well suited for that purpose are, for example, novolaks, derived from an aldehyde, typically acetaldehyde or furfuraldehyde, but especially from formaldehyde, and a phenol, for example unsubstituted phenol, mono- or di-chlorosubstituted phenol, such as p-chlorophenol, phenol mono- or di-substituted by C,-C9alkyl, such as o-, m- or p-cresol, the various xylenols, p-tert-butylphenol, p-nonylphenol, p-phenylphenol, resorcinol, bis(4-hydroxyphenyl)methane or 2,2-bis(4-hy-droxyphenyl)propane. Also suitable are homo- and copolymers based on ethylenically un-saturated phenols, for example homopolymers of vinyl- and 1-propenyl-substituted phenols, such as p-vinylphenol or p-(1-propenyl)phenol, or copolymers of these phenols with one or more than one ethylenically unsaturated compounds, for example styrenes. The amount of binder generally ranges from 30 to 95 % by weight or, preferably, from 40 to 80 % by weight.
The invention as a special embodiment includes negative photoresists having a resist thick-ness larger than 2 pm which are developable in alkaline medium for a working radiation of a wavelength between 340 and 390 manometers, comprising an oxime sulfonate of formula la as described above, an alkali-soluble phenolic resin as binder and a component that, when catalysed by an acid, undergoes a crosslinking reaction with itself and/or with the binder.
Particularly preferred negative photoresists comprise from 1 to 15 % by weight of oxime sul-fonate as acid generating-agent, from 40 to 99 % by weight of a phenolic resin as binder, for example one of those mentioned above, and from 0.5 to 30 % by weight of a melamine resin as crosslinking agent, the percentages relating to the solids content of the composition.
Using novolak or, in particular, polyvinyl phenol as binder gives a negative resist having es-pecially good properties.
It is preferred to use a negative resist comprising N-methoxymethyl melamine or tetrameth-oxymethylglucoril and N,N'-dimethoxymethylurone in high purity or technical form as amino resin.
Oximesulfonates are also used as acid generators which can be photochemically activated for the acid-catalysed crosslinking of, for example, poly(glycidyl)methacrylates in negative re-sist systems. Such crosslinking reactions are described, inter alia, by Chae et al. in Pollimo 1993, 17(3), 292.
Monomeric or polymeric compounds that are alkali-insoluble but are cleaved in the presence of an acid, or are capable of being rearranged intramolecularly, in such a manner that reac-tion products remain which are soluble in a customary alkaline developer and/or which cause an otherwise alkali-insoluble and acid-resistant additional binder to become soluble in the developer, also produce a positive characteristic in the novel photoresist compositions ac-cording to the invention. Substances of this type are referred to hereinafter as dissolution inhibitors.
The invention therefore includes, as a further special embodiment, positive photoresists de-velopable in alkaline medium for a working radiation of a wavelength of 340 to 390 nanome-ters, comprising a compound of formula I or la, respectively, having a molar extinction coefficient ~ below 10, and at least one compound which substantially prevents the composi-tion from dissolving in an alkaline developer, but which can be cleaved in the presence of an acid in such a manner that the remaining reaction products are soluble in the developer and/or which cause an acid-resistant additional binder that would otherwise be virtually insol-uble in the developer to dissolve in the developer.
There may be used as dissolution inhibitors monomeric and polymeric organic compounds having functional groups that would be soluble per se in an alkaline medium, for example a-romatic hydroxyl groups, carboxylic acid groups, secondary amino groups and keto or alde-hyde groups. These monomeric and polymeric organic compounds before their use as dis-solution inhibitors have been chemically altered by reaction with a suitable compound so that they are insoluble in aqueous alkali, the protective groups formed in the mentioned reaction being capable of being cleaved by acid catalysis in such a manner that the functional groups are recovered in their original form.
Suitable protective groups for the protection of hydroxyl groups, carboxylic acid groups or secondary amino groups are, for example, dihydrofuran or 3,4-dihydropyran and the deriva-tives thereof, benzyl halides, alkyl halides, haloacetic acids, haloacetates, chlorocarbonates, alkylsulfonyl halides, aromatic sulfonyl halides, dialkyl dicarbonates or trialkylsilyl halides.
The protective groups are introduced by customary reactions known to the person skilled in the art. Customary conversion into ketals and acetals is suitable for protecting keto and aldehyde groups. Such chemically amplified positive resist systems are described, inter alia, in E. Reichmanis, F. M. Houlihan, O. Nalamasu, T. X. Neenan, Chem. Mater.
1991, 3, 394;
or in C. G. Willson, "Introduction to Microlithography, 2nd. Ed.; L. S.
Thompson, C. G.
Willson, M. J. Bowden, Eds., Amer. Chem. Soc., Washington DC, 1994, p. 139.
Compounds carrying blocked aromatic hydroxyl groups are particularly preferred, which compounds may be monomers or polymers. The aromatic monomers preferably contain one or more than one aromatic nuclei, preferably 2 to 6 aromatic nuclei, containing 6 to 14, preferably 6, ring carbon atoms. In addition to containing the blocked hydroxyl groups, the aromatic nuclei may of course contain further substituents, preferably C1-C4alkyl, C,-C4alk-oxy or halogen. Particularly preferred monomeric dissolution inhibitors are bisphenyl types, i.e. compounds of formula Y ~ ~ Z ~ ~ Y , wherein each Y is an acid-sen-sitive group, such as a phenolic hydroxyl group, which is protected by a suitable acid-sen-sitive radical such as the ether, carbonate, silyl, tetrahydropyranyl or tetrahydrofuranyl groups (see e.g. EP 475903), and Z is either a direct single bond or is one of the radicals: -S-; -O-; -SO-; -SOz-; -CO-; -C(Ra)(Rb)-, wherein Ra is hydrogen, methyl or aryl, and Rb is hydrogen or methyl. Particularly preferred divalent radicals -C(Ra)(Rb)- are -CH2-; -C(CH3)z-and C(CH3)(Ph)-. The preferred polymeric dissolution inhibitors are derived from customary phenolic resins, typically from polyvinyl phenols, the hydroxyl groups of which are also bloc-ked in a manner consistent with the above description. Dissolution inhibitors carrying pro-tective groups of the indicated kind are known in the art. Inhibitors carrying carbonate groups are described, inter alia, by Dennis R. McKean, Scott A. McDonald, Nicholas J. Cle-cak and C. Grant Willson in "Novolac based deep-UV resists", SPIE Vol. 920 Advances in Resist Technology and Processing V (1988), p. 60-63, or by Masamitsu Shirai and Masahiro Tsunooka in "Photochemistry of Imino Sulfonate Compounds and their Application to Chemi-cally Amplified Resists", Journal of Photopolymer Science and Technology, Vol.
3(3), 1990, p. 301-304. The dissolution inhibitors carrying protective groups can be prepared by stan-dard known methods, for example as described by J. M. J. Frechet, E. Eichler, H. Ito and C.
G. Willson, Polymer 24 (1983), p. 995. Dissolution inhibitors carrying trialkylsilyloxy or tert-butyloxy groups are disclosed in EP 0329610, inhibitors carrying protective groups of the tetrahydrofuranyl and tetrahydropyranyl type group are described, inter alia, by N. Hayashi, S. M. A. Hesp, T. Ueno, M. Toriumi, T. Iwayanagi and S. Nonogaki in Polym.
Mat. Sci. Eng.
61 (1989), p. 417-421. Aromatic compounds carrying substituted tetrahydropyranyl groups are described in more detail in EP 0475903. The protective groups can be obtained in a manner known to the person skilled in the art by addition of 3,4-dihydropyrans or 3,4-dihy-drofurans under acid conditions.
In positive resists of the mentioned type a film-forming polymeric dissolution inhibitor can either be the only binder in the photoresist or can be used in admixture with an acid-inert bin-der and, where appropriate, a monomeric dissolution inhibitor.
Examples of acid-inert binders are novolaks, especially those based on o-, m-or p-cresol and formaldehyde, also polyp-hydroxystyrene), polyp-hydroxy-a-methylstyrene) and copo-lymers of p-hydroxystyrene, p-hydroxy-a-methylstyrene and acetoxystyrene.
Examples of polymeric dissolution inhibitors are novolaks, especially those based on o-, m-or p-cresol and formaldehyde, polyp-hydroxystyrene), poly(p-hydroxy-a-methylstyrene), co-polymers of p-hydroxystyrene or p-hydroxy-a-methylstyrene and acetoxystyrene or acrylic acid and/or methacrylic acid and also (meth)acrylic acid esters, which are reacted in a known manner with dihydrofuran, 3,4-dihydropyran, benzyl halides, alkyl halides, haloacetic acid, haloacetates, chlorocarbonates, alkylsulfonyl halides, aromatic sulfonyl halides, dialkyl dicarbonate or trialkylsilyl halides. Also suitable are polymers of p-(2-tetrahydropyranyl)oxy-styrene or p-(tert-butyloxycarbonyl)oxystyrene with (meth)acrylic acid, (meth)acrylates and/or p-acetoxystyrene and polymers of p-hydroxystyrene and/or p-(2-tetrahydropyranyl)-oxystyrene with 3-hydroxybenzyl (meth)acrylates, which can, if necessary, additionally be protected by reaction with one of the compounds listed above.
Particularly suitable are polymers that are transparent over a wavelength range from 180 to 1000 nm and which carry groups that, after acid-catalysed deprotecting, bring about a chan-ge in solubility, as well as hydrophobic and hydrophilic groups that increase the solubility of the acid generator and ensure aqueous-alkaline developability. Examples of such polymers are acrylates and methacrylates prepared by co- or ter-polymerisation from the correspon-ding monomers. The monomers may also carry organosilicon radicals in order, for example, to increase the resistance in the case of dry etching processes. Examples of corresponding monomers are: methyl (meth)acrylate, (meth)acrylic acid, tert-butyl (meth)acrylate, trimethyl-silylmethyl (meth)acrylate, 3-oxocyclohexyl (meth)acrylate, tetrahydropyranyl (meth)acrylate, adamantyl (meth)acrylate, cyclohexyl (meth)acrylate, norbornyl (meth)acrylate.
The invention accordingly also relates to a chemically amplified positive resist comprising as photosensitive acid generator a compound of formula I or la, having a molar extinction coef-ficient ~ below 10 respectively, as well as to a photoresist comprising polymers that are transparent up to the wavelength region of 180 nm.
A special embodiment of the positive resist according to the invention comprises from 75 to 99.5 % by weight of a film-forming polymer that contains protective groups which can be re-moved by acid catalysis, and from 0.5 to 25 % by weight of oxime sulfonates of formula I or formula la, having a molar extinction coefficient g below 10, the percentages being based on the solids content of the compositions. In this context, preference is given to compositions comprising from 80 to 99 % by weight of the mentioned polymer and from 1 to 20 % by weight of oxime sulfonate.
Another embodiment is a positive resist comprising from 40 to 90 % by weight of an acid-in-ert film-forming polymer as binder, from 5 to 40 % by weight of a monomeric or polymeric compound having protective groups removable by acid catalysis, and from 0.5 to 25 % by weight of oxime sulfonates of formula I or la, as described above, the percentages relating to the solids content of the compositions. Preference is given to compositions comprising from 50 to 85 % by weight of acid-inert binder, from 10 to 30 % by weight of monomeric or polymeric dissolution inhibitor and from 1 to 15 % by weight of oxime sulfonates.
Oxime sulfonates can also be used as solubilisers which can be activated by light. In that case, the compounds are added to a film-forming material comprising substantially no com-ponents that polymerise with the oxime sulfonate when heated or when irradiated with actinic radiation. However, the oxime sulfonates reduce the speed at which the film-forming mater-ial dissolves in a suitable developer medium. This inhibiting effect can be cancelled by irra-diating the mixture with actinic radiation, so that a positive image can be produced. Such an application is described, for example, in EP 241423.
A further special embodiment of the invention is a positive resist comprising a compound of formula I or la, having a molar extinction coefficient ~ below 10, respectively, and a binder which is virtually insoluble in an alkaline developer and which becomes soluble in the devel-oper in the presence of the photolysis products of the compound of formula I
or la. In this case the amount of the mentioned oximesulfonate compound of formula I or la is generally from 5 to 50 % by weight, based on the solids content of the composition.
The use of the oxime sulfonates according to the invention in chemically amplified systems, which operate on the principle of the removal of a protective group from a polymer, generally produces a positive resist. Positive resists are preferred to negative resists in many appli-cations, especially because of their better resolution. There is, however, also interest in pro-ducing a negative image using the positive resist mechanism, in order to combine the ad-vantages of the high degree of resolution of the positive resist with the properties of the ne-gative resist. This can be achieved by introducing a so-called image-reversal step as des-cribed, for example, in EP 361906. For this purpose, the image-wise irradiated resist mater-ial is treated, before the developing step, with e.g. a gaseous base, thereby neutralizing the acid that has been produced image-wise. Subsequently, a second irradiation, over the whole area, and thermal aftertreatment are carried out and the negative image is finally de-veloped in the customary manner.
In addition to the cited components, it is also possible to add compounds which accelerate or amplify the acid formation to the negative as well as to the positive photoresist compositions containing the oxime sulfonate. Such acid amplifiers are described, inter alia, in K. Arimitsu et al., J. Photopolym. Sci Technol. 1995, 8, pp. 43, K. Kudo et al., J.
Photopolym. Sci Technol. 1995, 8, pp. 45, or K. Ichimura et al. Chem. Lett. 1995, pp. 551.
In addition to the mentioned constituents, both the negative and the positive photoresist compositions may additionally comprise one or more of the additives customarily used in photoresists in the amounts familiar to a person skilled in the art. Examples for such additiv-es are flow control agents, wetting agents, adhesives, thixotropic agents, colourants, pig-ments, fillers, dissolution accelerators and so on. However, substances which additionally sensitise the compositions for the working irradation in the range of the mercury i-line should not be added because this would normally result in a reduced resolution of the resist.
For certain purposes, resin mixtures having monomeric or oligomeric constituents containing polymerisable unsaturated groups are used. Such surface coatings can also be cured using the compounds of formula I or la as described above. In addition to component c), it is pos-sible to use 1. radical polymerisation initiators or 2. photoinitiators. The former initiate the polymerisation of the unsaturated groups by heat treatment, the latter by UV
radiation.
Examples of additional photoinitiators for use in the compositions according to the invention are, for example, radical photoinitiators, typically those from the class of the benzophenones, acetophenone derivatives, such as a-hydroxycycloalkylphenyl ketone, dialkoxyacetophen-one, a-hydroxyacetophenone or a-aminoacetophenone, 4-aroyl-1,3-dioxolane, benzoin alkyl ethers and benzil ketals, phenylglyoxalic esters and derivatives thereof, dimeric phenylglyox-alic esters, peresters, e,g. benzophenone tetracarboxylic peresters as described for example in EP 126541, monoacylphosphine oxides, bisacylphosphine oxides or titanocenes.
Illustrative examples of particularly suitable additional photoinitiators are:
1-(4-dodecylben-zoyl)-1-hydroxy-1-methylethane, 1-(4-isopropylbenzoyl)-1-hydroxy-1-methyl-ethane, 1-ben-zoyl-1-hydroxy-1-methylethane, 1-[4(2-hydroxyethoxy)benzoyl]-1-hydroxy-1-methylethane, 1-(4(acrylolyoxyethoxy)benzoyl]-1-hydroxy-1-methylethane, diphenyl ketone, phenyl-1-hydroxycyclohexyl ketone, (4-morpholinobenzoyl)-1-benzyl-1-dimethylaminopropane, 1-(3,4-dimethoxyphenyl)-2-benzyl-2-dimethylaminobutan-1-one, (4-methylthiobenzoyl)-1-methyl-1-morpholinoethane, benzil dimethyl ketal, bis(cyclopentadienyl)-bis(2,6-difluoro-3-pyrrylphenyl)titanium, trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-(2,4,4-trimethyl-pentyl)phosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,4-dipentoxyphenyl-phosphine oxide or bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide. Other suitable additional photoinitiators are for example disclosed in US 4950581, column 20, line 35 to column 21, line 35. Other examples are trihalomethyltriazine derivatives or hexaarylbisimid-azolyl compounds.
Further examples of additional photoinitiators are also cationic photoinitiators, typically per-oxide compounds, such as benzoylperoxide (other suitable peroxides are described in US
4950581, column 19, lines 17-25), aromatic sulfonium salts or iodonium salts, such as those disclosed, inter alia in US 4950581, column 18, line 60 to column 19, line 10, or cyclopenta-dienyl-arene-iron(II)-complex salts, typically (rts-isopropylbenzol)(rls-cyclopentadienyl)-iron-II-hexafluorophosphate.
For application, the compositions generally also comprise a solvent. Examples of suitable solvents are acetone, methyl ethyl acetone, ethyl acetate, 3-methoxymethyl propionate, ethyl pyruvate, 2-heptanone, diethyl glycol dimethyl ether, cyclopentanone, cyclohexanone, y-bu-tyrolactone, ethyl methyl ketone, 2-ethoxyethanol, 2-ethoxyethyl acetate and, in particular, 1-methoxy-2-propyl acetate or propylene glycole methyl ether acetate. The solvent may also be added as a mixture, for example of two or more of the above-mentioned solvents. The choice of solvent and the concentration depend, for example, on the nature of the composi-tion and on the coating method.
The solution is uniformly applied to a substrate by means of known coating methods, for ex-ample by spin-coating, immersion, knife coating, curtain coating techniques, brush applica-tion, spraying and reverse roller coating. It is also possible to apply the photosensitive layer to a temporary, flexible support and then to coat the final substrate by coating transfer (lami-nating).
The amount applied (coating thickness) and the nature of the substrate (coating substrate) are dependent on the desired field of application. The range of coating thicknesses can in principle include values from approximately 0.1 pm to more than 100 pm but in the conntext of the present invention particularly values > 2 p,m are preferred. Especially preferred are coating thicknesses from 2 pm to 100 pm, for example 2.5 pm to 60 wm or 2.5 pm to 20 p.m.
Possible areas of use of the composition according to the invention are as follows: use as photoresists for electronics, such as etching resists, electroplating resists or solder resists, the manufacture of integrated circuits or thin film transistor resist (TFT
resist), the manufac-ture of printing plates, such as offset printing plates or screen printing templates, use in the etching of mouldings or in stereolithography techniques, use in colour filters or image recor-ding materials and all other types of lithographic imaging processes and, preferably, use as microresist in the manufacture of integrated circuits. The coating substrates and processing conditions vary according to the application and are customary in the art.
When using the compositions as microresists for integrated and large-scale integrated circu-its, as preferred, the layer thicknesses are typically from 2 to 30 pm, preferably from 2 to 10 pm. Preferred use is made of process steps where the relatively large thickness results in certain advantages or is required to obtain the desired functionality. One example of such an application are resists for ion implantation with coating thicknesses ranging typically from 2 to 10 pm, preferably from 2 to 7 Vim.

The compositions according to the invention are also outstandingly suitable as coating com-positions for substrates of all types, including wood, textiles, paper, ceramics, glass, plastics, such as polyesters, polyethylene terephthalate, polyolefins or cellulose acetate, especially in the form of films, and especially for coating metals, such as Ni, Fe, Zn, Mg, Co or especially Cu and AI, and also Si, silicon oxides or nitrides, to which an image is to be applied by means of image-wise irradiation. The meaning of the term "image-wise"
irradiation is explained below.
After the coating operation, the solvent is generally removed by heating, resulting in a layer of the photoresist on the substrate. The drying temperature must, of course, be lower than the temperature at which certain components of the resist might be thermally cured. Care must be taken in that respect especially in the case of negative photoresists.
In general, dry-ing temperatures are in the range from 80 to 140°C.
The resist coating is then irradiated image-wise. This irradiation in a predetermined pattern using actinic radiation includes both irradiation through a photomask containing a predeter-mined pattern, for example a diapositive, and irradiation using a laser beam that is moved over the surface of the coated substrate, for example under the control of a computer, and thus produces an image.
Suitable radiation sources are those which emit radiation of a wavelength in the working ran-ge of the resist, for example between 340 to 390 nanometers. Both point sources and plani-form projectors (arrays of reflector lamps) are suitable. Examples are: carbon arc lamps, xenon arc lamps, medium pressure, high pressure and low pressure mercury lamps, opt-ionally doped with metal halides (metal halide lamps), microwave-excited metal vapour lamps, excimer lamps, superactinic fluorescent tubes, fluorescent lamps, argon filament lamps, electronic flash lamps, photographic flood lights, electron beams and X-ray beams generated by means of synchrotrons or laser plasma. Particularly suitable are mercury vapour lamps, especially mercury medium- and high-pressure lamps, from whose radiation the emission lines at other wavelengths are filtered out, if required. This is the case in particular for short-wave radiation. The distance between the lamp and the substrate according to the invention to be irradiated can vary, for example, from 2 cm to 150 cm, according to the intended use and the type and/or strength of the lamp. A
suitable laser-beam source is, for example, the argon-ion laser, which emits radiation at wavelengths of 364 and 388 nanometers. With that type of irradiation, it is not absolutely essential to use a photomask in contact with the photopolymeric coating; the controlled laser beam is capable of writing directly onto the coating. For that purpose the high sensitivity of the materials according to the invention is very advantageous, allowing high writing speeds at relatively low intensities. On irradiation, the oxime sulfonate in the composition in the irradiated sections of the surface coating decomposes to form sulfonic acids. If lamps are used emitting light in a wavelength range exceeding the range of 340-390 nm, the working wave-length is selected by using filter equipment. Generally interference filters are employed.
After the irradiation and, if necessary, thermal treatment, the unirradiated sites (in the case of positive resists) or the irradiated sites (in the case of negative resists) of the composition are removed in a manner known per se using a developer.
It is generally necessary to allow a certain period of time prior to the developing step in order to allow the acid-sensitive components of the resist composition to react. In order to acceler-ate this reaction and hence the development of a sufficient difference in solubility between the irradiated and unirradiated sections of the resist coating in the developer, the coating is preferably heated before being developed. The heating can also be carried out or started during the irradiation. Temperatures from 60 to 160°C are preferably used. The period of time depends on the heating method and, if necessary, the optimum period can be deter-mined easily by a person skilled in the art by means of a few routine experiments. It is generally from a few seconds to several minutes. For example, a period of from 10 to 300 seconds is very suitable when a hotplate is used and from 1 to 30 minutes when a convecti-on oven is used.
The coating is then developed, the portions of the coating that, after irradiation, are more so-luble in the developer being removed. If necessary, slight agitation of the workpiece, gentle brushing of the coating in the developer bath or spray developing can accelerate that pro-cess step. The aqueous-alkaline developers customary in resist technology may be used for the developing. Such developers comprise, for example, sodium or potassium hydroxide, the corresponding carbonates, acid carbonates, silicates or metasilicates, but preferably me-tal-free bases, such as ammonia or amines, for example ethylamine, n-propylamine, dieth-ylamine, di-n-propylamine, triethylamine, methyl diethylamine, alkanolamines, for example dimethyl ethanolamine, triethanolamine, quaternary ammonium hydroxides, for example tetramethylammonium hydroxide or tetraethyl ammonium hydroxide. The developer solutions are generally up to 0.5N, but are usually diluted in suitable manner before use. For example solutions having a normality of approximately 0.1 are well suited. The choice of developer depends on the nature of the photoresist, especially on the nature of the binder used or on the resulting photolysis products. The aqueous developer solutions may, if necessary, also comprise relatively small amounts of wetting agents and/or organic solvents.
Typical organic solvents which can be added to the developer fluids are, for example, cyclohexanone, 2-ethoxyethanol, toluene, acetone, isopropanol and also mixtures of two or more of these solvents. A typical aqueous/organic developer system is based on BU-TYLCELLOSOLVE~/water.
Accordingly, this invention also relates to a process for the production of an image, which comprises (a) coating a substrate with a composition as described above, (b) irradiating the coating with radiation having a wavelength of 340 to 390 nanometers in a desired pattern and, after a heating period to temperatures of 60 to 160°C (c), (d) removing the more soluble sections of the coating with an aqueous-alkaline developer.
In another of its aspects, this invention also relates to the use of the compositions described above for the production of printing plates, colour filters, resist materials and image recor-ding material, as well as to the use of such compositions for the production of printing plates, colour filters, resist materials or image recording materials, or for image recording materials for holographic images, as well as to the use of compounds of formula I or la, having a molar extinction coefficient a below 10, as photosensitive acid generator sensitive to radiation at a wavelength of below 390 nm in the production of printing plates, colour filters, resist materials or image recording materials, or for image recording materials for holographic images.
In addition to a colour change, it is possible during the acid-catalysed deprotection of soluble pigment molecules for the pigment crystals to be precipitated; this can be used in the pro-duction of colour filters.
The compounds of formula I or la, respectively, are normally added to the compositions which can be activated by light in an amount of 0.1 to 30 % by weight, e.g. of 0.5 to 20 % by weight, preferably of 1 to 10 % by weight.

Subject of the invention also is a negative photoresist according to claim comprising as acid generating compound of formula la a-(methane sulfonium oxyimino)-3,4-dimethyl-phenyla-cetonitrile, a-(methanesulfoniumoxyimino)-4-methyl-phenylacetonitrile, or a-(4-toluene-sulfoniumoxyimino)-phenylacetonitrile.
The following Examples illustrate the invention in more detail. As in the remainder of the description and in the patent claims, parts and percentages are by weight, unless otherwise stated.
Example 1:
A negative resist composition is prepared by mixing 70 parts by weight of polyvinylphenol resin (Maruzen Chemical Co. Ltd.), 25 parts by weight of hexamethoxymethylmelamine, CYMEL-303~ (American Cyanamide) and 150 parts by weight of propylene glycol methyl ether acetate.
Separately 5 parts by weight of the acid-generating agent represented by a-(methane sulfo-nium oxyimino)-3,4-dimethyl-phenylacetonitrile (having an E of 4.1 in a tetrahydrofuran soluti-on at 365 nm) are dissolved in 10 parts by weight of N,N-dimethylacetamide.
Both solutions are mixed to form the resist solution.
A silicon wafer is uniformly coated with this prepared resist solution on a spinner followed by drying at 110°C for 90 seconds to give a dried photoresist layer having a thickness of 5 Vim.
The resist layer is exposed with a maskaligner (Canon PLA501 ) using the interference filter to select the i-line, 365 nm, followed by a post-exposure baking at 110°C for 90 seconds.
The resulting formulation is subjected to a development treatment in a 2.38 %
by weight a-queous solution of tetramethylammonium hydroxide for 60 seconds, afterwards is washed with water and dried by air.
The photosensitivity of line-and-space of 2 ~m represented by the exposure dose at which the resist layer on the exposed areas could be completely formed at 1:1 ratio was 210 mJ/cm2 (energy).
Further, a resist layer patterned in a line-and-space pattern of 2 ~m line width is formed in the same manner as above and examined with a SEM (scanning electron microscope) for the cross sectional profile of the line pattern. It is found that the cross section has a rectan-gular form standing perpendicularly to the substrate. The relative width of the line prepared by varying the exposure dose between 0.8 and 1.2 times against the photosensitivity obtain-ed above is plotted against the relative energy applied. The slope of a fitting line is 0.28.
The lower the slope, the better is the lattitude of the tested system.
Example 2:
A resist formulation according to example 1 is prepared. However, as acid generating agent instead of a-(methanesulfoniumoxyimino)-3,4-dimethyl-phenylacetonitrile 5 parts by weight of a-(methanesulfoniumoxyimino)-4-methyl-phenylacetonitrile (having an a of 0.35 in a tetra-hydrofuran solution at 365 nm) are used.
Following the same conditions as described in Example 1 the resulting photosensitivity is 300 mJ/cm2. The cross sectional profile of the resist layer of 2 ~,m line width examined with a SEM (scanning electron microscope) is a rectangular form standing perpendicularly to the substrate. The slope determined in the same way as described in example 1 is 0.31.
Example 3:
A resist formulation according to example 1 is prepared. However, as acid generating agent instead of a-(methanesulfoniumoxyimino)-3,4-dimethyl-phenylacetonitrile 5 parts by weight of a-(4-toluenesulfoniumoxyimino)-phenylacetonitrile (having an a of 0.28 in a tetrahydrofur-an solution at 365 nm) are used.
Following the same conditions as described in Example 1 the resulting photosensitivity is 500 mJ/cm2. The cross sectional profile of the resist layer of 2 ~m line width examined with a SEM (scanning electron microscope) is a rectangular form standing perpendicularly to the substrate. The slope is 0.42.
Comparative example:
A resist solution was prepared in substantially the same manner as described in example 1 except for replacement of the acid generating agent with 5 parts of a-(methanesulfoniumoxyimino)-2-thiophenylacetonitrile having an E of 58 in a tetrahydrofuran solution at 365 nm. The result of the evaluation is a photosensitivity of 60 mJ/cm2 and a slope of 0.72.

Claims (16)

1. A composition which can be activated by light, comprising (a) at least one compound which may be crosslinked by the action of an acid and/or (b) at least one compound which changes its solubility under the action of an acid, and (c) as photoinitiator at least one compound generating an acid under the exposure of light of a wavelength of 240 to 390 nm and having a molar extinction coefficient .epsilon. below 10 at i-line (365 nm).

2. A composition according to claim 1, comprising as component (c) a compound comprising a structural unit of formula I
and wherein the compounds are characterized by a molar extinction coefficient .epsilon. below 10 at 365 nm.

3. A composition according to claim 1, comprising as component (c) a compound of formula Ia (la) , wherein R1, R2, R3, R4 and R5 independently of one another are hydrogen, unsubstituted or halogen-substituted C1-C12alkyl; or R1, R2, R3, R4 and R5 are halogen;
R6 is unsubstituted or halogen-substituted C1-C18alkyl, phenyl-C1-C3alkyl, camphoryl, phenyl, naphthyl, anthracyl or phenanthryl, the radicals phenyl, naphthyl, anthracyl and phenanthryl being unsubstituted or substituted by one or more of the radicals halogen, C1-C4haloalkyl, CN, NO2, C1-C16alkyl, phenyl, OR10, COOR9, -O(CO)-C1-C4alkyl, and/or by NR7R8;
R7 and R8 independently of each other are hydrogen or C1-C12alkyl, which is unsubstituted or substituted by OH, C1-C4alkoxy, C1-C12alkylsulfonyl, phenylsulfonyl, (4-methylphenyl)-sulfonyl and/or by C1-C6alkanoyl; or R7 and R8 are C2-C12alkyl, which is interrupted by -O- and which is unsubstituted or substituted by OH, C1-C4alkoxy, C1-C12alkylsulfonyl, phenylsulfonyl, (4-methylphenyl)sulfonyl and/or by C1-C6alkanoyl; or R7 and R8 are phenyl, C2-C6alkanoyl, benzoyl, C1-C6alkylsulfonyl, phenylsulfonyl, (4-methylphenyl)-sulfonyl, naphthylsulfonyl, anthracylsulfonyl or phenanthrylsulfonyl; or R7 and R8, together with the nitrogen atom to which they are linked, form a 5-, 6- or 7-membered ring which may be interrupted by -O- or by -NR11-;
R9 is C1-C12alkyl which is unsubstituted or substituted by OH and/or by C1-C4alkoxy, or R9 is C2-C12alkyl which is interrupted by -O- and which is unsubstituted or substituted by OH
and/or by C1-C4alkoxy;
R10 is hydrogen; C1-C12alkyl which is unsubstituted or substituted by phenyl, OH, C1-C12-alkoxy, C1-C12alkylsulfonyl, phenylsulfonyl, (4-methylphenyl)sulfonyl and/or by C2-C6-alkanoyl;
or R10 is C2-C12alkyl which is interrupted by -O- and which is unsubstituted or substituted by phenyl, OH, C1-C12alkoxy, C1-C12alkylsulfonyl, phenylsulfonyl, (4-methyl-phenyl)sulfonyl and/or by C2-C6alkanoyl; or R10 is phenyl;
R11 is hydrogen, unsubstituted or OH-substituted C1-C12alkyl, or C2-C12alkyl which is interrupted by -O-;
and wherein the compounds of formula Ia are characterized by a molar extinction coefficient .epsilon. below 10 at 365 nm.

4. A chemically amplified photoresist, which is sensitive to radiation in the range from 340 to 390 nm, comprising a photosensitive acid generator of formula I, as defined in claim 2, characterized by a molar extinction coefficient .epsilon. below 10 at 365 nm.

5. A chemically amplified photoresist according to claim 4, which is sensitive to radiation in the range from 340 to 390 nm, comprising a photosensitive acid generator of formula Ia, as defined in claim 3, characterized by a molar extinction coefficient .epsilon.
below 10 at 365 nm.

6. A chemically amplified photoresist according to claim 4 or 5 having a thickness of more than 2 µm.

7. A chemically amplified negative photoresist comprising a compound of formula Ia, having a molar extinction coefficient .epsilon. below 10, which is developable in alkaline medium, having a resist thickness larger than 2 µm and which is sensitive to radiation in the range from 340 to 390 nanometers.

8. A negative photoresist having a resist thickness of morer than 2 µm which is developable in alkaline medium for a working radiation of a wavelength between 340 and 390 nanometers, comprising an oxime sulfonate of formula Ia as described in claim 3, an alkali-soluble phenolic resin as binder and a component that, when catalysed by an acid, undergoes a crosslinking reaction with itself and/or with the binder.

9. A chemically amplified positive photoresist comprising a compound of formula Ia, having a molar extinction coefficient a below 10, which is developable in alkaline medium, having a resist thickness larger than 2 µm and which is sensitive to radiation in the range from 340 to 390 nanometers.

10. A positive photoresist comprising a compound of formula Ia, as defined in claim 3, and a binder which is virtually insoluble in an alkaline developer and which becomes soluble in the developer in the presence of the photolysis products of the compound of formula Ia.

11. Use of a composition according to claim 1 for the preparation of negative chemically amplified photoresists, positive photoresists, printing plates, color filters or image recording materials.

12. A process for the production of negative chemically amplified photoresists, positive photoresists, printing plates, color filters or image recording materials, wherein a composition according to claim 1 is irradiated with light of a wavelength of 340 to 390 nm.

13. A process for the production of an image, which comprises (a) coating a substrate with a composition according to claim 1, (b) irradiating the coating with radiation having a wavelength of 340 to 390 nanometers in a desired pattern, (c) heating the coating to temperatures of 60 to 160°C, and (d) removing the more soluble sections of the coating with an aqueous-alkaline developer.

14. Use of a compound of formula I or Ia, having a molar extinction coefficient s below 10, as photoacid generator in compositions comprising compounds which can be crosslinked by the action of an acid or/and as dissolution inhibitor for compounds which change their solubility under the action of an acid.

15. A process for generating sulfonic acids, wherein a photoacid generator of formula Ia, having a molar extinction coefficient .epsilon. below 10, is irradiated with light in a wavelength range from 340-390 nm.

16. A negative photoresist according to claim 8 comprising as acid generating compound of formula Ia .alpha.-(methane sulfonium oxyimino)-3,4-dimethyl-phenylacetonitrile, .alpha.-(methanesulfoniumoxyimino)-4-methyl-phenylacetonitrile, or .alpha.-(4-toluenesulfoniumoxyimino)-phenylacetonitrile.