AU4452799A - Sulfonyloximes for i-line photoresists of high sensitivity and high resist thickness - Google Patents

Description

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AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT r Applicant(s): Address for Service: Invention Title: Ciba Specialty Chemicals Holding Inc.

Klybeckstrasse 141 CH-4057 Basel

SWITZERLAND

DAVIES COLLISON CAVE Patent Trade Mark Attorneys Level 10, 10 Barrack Street SYDNEY NSW 2000 Sulfonyloximes for i-line photoresists of high sensitivity and high resist thickness The following statement is a full description of this invention, including the best method of performing it known to me:- 5020 A-21814/A/CGJ 110 -1- 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 developable 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 nanometers. 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 temperatures. 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 converted to the soluble form of the free acid by irradiation. Combined with a suitable film-forming 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 particularly 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 radiation having the wavelength of the mercury i-line (365nm), can be used as catalysts for different acid-catalysed reactions, such as polycondensation reactions, acid-catalysed depolymerisation 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 e 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 bombardment. 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 photoresists 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 compounds with short alkyl-sulfonic acid groups (C1-C4) are used having a molar extinction coefficient E 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 -3the 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 chemically 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 E below 10. This applies both to negative as well as to positive photoresists containing an acid-sensitive component that undergoes an acid-catalysed chemical reaction which changes the solubility of the compositons in aqueous-alkaline developers.

Accordingly, this invention relates to compositions 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 an acid under the exposure of light of a wavelength of 240 to 390 nm and having a molar extinction coefficient E below 10 at iline (365 nm).

In particular, the compound is a compound generating a sulfonic acid.

Preferred are compositions having a thickness larger than 2 pm when coated onto a :i substrate.

The invention further relates to composition as described above, comprising as component a compound comprising a structural unit of formula I C=N-0-SO 2 and wherein the compounds are characterized by a molar extinction coefficient E below 10 at 365 nm.

Preferred compositions are such, comprising as component a compound of formula la -4-

NC

RI CN0S2R R2 (la) wherein

/R

Ri, R 2

R

3

R

4 and R 5 independently of one another are hydrogen, unsubstituted or halogensubstituted Cl-C 12 alkyl; or RI, R 2

R

3

R

4 and R 5 are halogen;e

R

6 is unsubstituted or halogen-substituted C 1 -Ci 8 alkyl, phenyl-C 1

-C

3 alkyl, camphoryl, phenyl, naphthyl, anthracyl or phenanthryl, the radicals phenyl, naphthyt, anthracyl and phenanthryl being unsubstituted or substituted by one or more of the radicals halogen, 0 1

-C

4 haloalkyl, ON, NO 2 0 1

-C

16 alkyl, phenyl, ORI 0

COOR

9

-O(CO)-C

1

-C

4 alkyl, S0 2 0Rq and/or by NR 7

R

8

R

7 and R 8 independently of each other are hydrogen or Ci-C 12 alkyl, which is unsubstituted or substituted by OH, C 1

-C

4 alkoxy, Cl-C 12 alkylsulfonyl, phenylsulfonyl, (4-methylphenyl)sulfonyl and/or by 0 1 -C~alkanoyl; or R 7 and R 8 are C 2

-C

12 alkyl, which is interrupted by and which is unsubstituted or substituted by OH, C 1

-C

4 alkoxy, C 1 -Cl 2 alkylsulfonyl, phenylsutfonyl, (4-methylphenyl)sulfonyl and/or by C 1

-C

6 alkanoyl; or R 7 and R 8 are phenyl, C 2

-C

6 alkanoyl, benzoyl, 0 1

-C

6 alkylsulfonyl, phenylsulfonyl, (4-methylphenyl)sulfonyl, naphthylsulfonyl, anthracylsulfonyl or phenanthrylsulfonyl; or R 7 and R 8 together with the nitrogen atom to which they are linked, form a 6- or 7-membered ring which may be interrupted by or by -NR 11

*R

9 is CI-O 12 alkyl which is unsubstituted or substituted by OH and/or by C 1

-C

4 alkoxy, or R 9 is 0 2 -Cl 2 alkyl which is interrupted by and which is unsubstituted or substituted by OH and/or by 0 1

-C

4 alkoxy; Rio is hydrogen; 0 1 -Cl 2 alkyl which is unsubstituted or substituted by phenyl, OH, Cl-C12alkoxy, Cl-Cl 2 alkylsulfonyl, phenylsulfonyl, (4-methylphenyl)sulfonyl and/or by C2-C6alkanoyl; or Rio is 0 2

-C

12 alkyl which is interrupted by and which is unsubstituted or substituted by phenyl, OH, Cl-Cl 2 alkoxy, C 1

-C

12 alkylsulfonyl, phenylsulfonyl, (4-me thylphenyl)sulfonyl and/or by 0 2

-C

6 alkanoyl; or Rio is phenyl;

R

11 is hydrogen, unsubstituted or OH-substituted 0 1

-C

12 alkyl, or C 2 -Cl 2 alkyl which is interrupted by and wherein the compounds of formula la are characterized by a molar extinction coefficient F_ below 10 at 365 nm.

According to this invention it is also possible to use mixtures of isomeric forms (cis-trans isomers, E/Z- or syn/anti-isomers) of the oxime sulfonates of formula la.

C

1 -Cj 8 alky is linear or branched and is, for example, C 1

-C

1 6 C1-C14, 01-012-, C1-C8-, C1 C6or C 1

-C

4 alkyl. Examples are methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tertbutyl, pentyl, hexyl, heptyl, 2,4,4-trimethylpentyl, 2-ethylhexyl, octyl, nonyl, decyl, dodecyl, tetradecyl, pentadecyl, hexadecyl and octadecyl.

C

1 -Cl 6 alkyl, C 1

-C

1 2 alkyl and C 1

-C

4 alkyl have the same meanings as given above for C 1

-C

8 lealkyl 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 1

-C

1 8 alkyl or halogen-substituted C 1

-C

1 2 alkyl are alkyl radicals as described above, which have one or more than one same or different halogen atoms as substi- Stuents. 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, bromomethyl, trifluoromethyl, 1-chlorethyl, 2-chlorethyl and the like.

C

1

-C

4 haloalkyl corresponds to C 1

-C

4 alkyl which is substituted by halogen. The same explanations as given above apply for these radicals, up to the corresponding number of C-atoms.

C

2

-C

12 alkyl, which is interrupted by is linear or branched and is for example, interrupted 1-6 times, for example 1-3 times or once or twice by The O-atoms in the alkyl chain are positioned non-successive. This produces structural units such as, for example,

-CH

2

-O-CH

2

-CH

2

CH

2

CH

2

CH

2

-[CH

2

CH

2

-[CH

2

CH

2 0,-CH 2 where y 1-6 and z 1-5, -(CH 2

CH

2 0) 5

CH

2

CH

2

-CH

2

-CH(CH

3 )-0-CH 2

-CH(CH

3 or

-CH

2

-CH(CH

3

)-O-CH

2

-CH

2

CH

2

C

1

-C

1 2 Alkoxy is a linear or branched radical and is C1-C8-, C1-C6-, C-C 4 alkoxy, for example, methoxy, ethoxy, propoxy, isopropoxy, n-butyloxy, sec-butyloxy, isobutyloxy, tert-butyloxy, pentyloxy, hexyloxy, heptyloxy, 2,4,4-trimethylpentyloxy, 2-ethylhexyloxy, octyloxy, nonyloxy, -6decyloxy or dodecyloxy, especially methoxy, ethoxy, propoxy, isopropoxy, n-butyloxy, sbutyloxy, iso-butyloxy or tert-butyloxy, preferably methoxy.

C

1

-C

4 alkoxy has the same meanings as given above up to the corresponding number of Catoms.

Ci-C 1 2 alkylsulfonyl means C 1 -Ci 2 alkyl-O-SO 2 wherein the C 1

-C

1 2 alkyl radicals are defined as described above.

C

1

-C

6 alkanoyl is linear or branched and is, for example, Ci-C 4 alkanoyl. Examples are formyl, acetyl, propionyl, butanoyl, isobutanoyl, pentanoyl or hexanoyl, preferably acetyl.

Phenyl-C 1

-C

3 alkyl 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.

4i If R 7 and R 8 together with the nitrogen atom to which they are linked, form a 6- or 7-membered ring which may be interrupted by or by -NRI-, 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 (substituents).

The term "at least" is meant to define one or more than one.

The molar extinction coefficient E 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 E is part of the Lambert Beer equation, which is familiar to the person skilled 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 e-values are slightly shifting depending on the solvent used to measure the UVspectrum 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 E below 10 is suitable for the compositions according to the present invention, or the claimed photoresists respectively. Suitable are for example compounds generating Lewis acids as well as compounds generating Bronsted acids, for example compounds generating carboxylic acids, sulfonic acids, phosphonic acids, PF6-, BF 4 SbFs 5 and the like.

Examples of such compounds are sulfonium- and iodonium salts as well as derivatives of P* nitrobenzylsulfonates and bis-sulfonyl diazo methanes.

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 extinction coefficient e below 10, wherein

R

1

R

2

R

3

R

4 and Rs independently of one another are hydrogen, C 1 -Cealkyl, halogen, or C,-

C

4 haloalkyl; and R is C 1 -Cs 1 alkyl, phenyl-Cl-C 3 alkyl, camphoryl, Cl-Clohaloalkyl, phenyl, naphthyl, anthracyl or phenanthryl, wherein the radicals phenyl, naphthyl, anthracyl and phenanthryl are unsubstituted or substituted by one or more of the radicals halogen, C 1

-C

4 haloalkyl, CN, NO 2

C-

C

1 6 alkyl, phenyl, ORio; and Rio is defined as above.

The compositions preferably comprise compounds of formula la, having a molar extinction coefficient e below 10, wherein Ri ,R 2

R

3

R

4 and Rs independently of one another are hydrogen, C 1

-C

4 alkyl, halogen, or C 1

C

4 haloalkyl, with the proviso that at least two of the radicals R 1

R

2

R

3

R

4 or Rs are hydrogen; and

R

6 is Ci-C 12 alkyl, phenyl-C 1

-C

3 alkyl, camphoryl, C 1

-C

4 haloalkyl, or phenyl, wherein the phenyl radical is unsubstituted or substituted by one or more halogen, C 1

-C

4 haloalkyl, NO 2

CI-C

8 alkyl, phenyl or ORio; and -8- RIO is C 1

-C

12 alkyl.

Examples of latent sulfonic acids of formula [a are the methanesulfonates, butanesulfonates, benzenesulfonates, 4-methylphenylsulfonates, 4-methoxybenzenesulfonates and camphorsulfonates of ax-hydroxyimino-4-methylbenzylcyanide, a-hydroxyimino-4-butylbenzylcyanide, c-hydroxyimino-3-methylbenzylcyanide, a-hydroxyimino-2-methytbenzylcyanide, ac-hydroxyimino-2,4-dimethylbenzylcyanide, a-hydroxyimino-3,4-dimethylbenzylcyanide, c-hydroxyimino-3,4-dibutylbenzylcyanide, a-hydroxyimino-2,4,6-tnmethylbenzylcyanide, a-hydroxyimino-2-chlorobenzylcyanide a-hydroxyimino-2,4-dichlorobenzylcyanide, *a-hydroxyimino-4-chlorobenzylcyanide, c-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 NC0 C CN- OH CI-S0 2

-R

6 01 CN-O-S-R6 R R I I 6 0 (Ia) wherein R is wherei R isand RI, R 2

R

3

R

4

R

5 and R 6 are as defined above.

M M_ The reaction is conveniently carried out in an inert organic solvent in the presence of a tertiary amine.

The sodium salts of the oximes are obtained, for example, by reacting the corresponding oxime with a sodium alcoholate in dimethylformamide (DMF).

The oxime sulfonates are obtained in the syn- cis) or anti- trans) form or also as mixtures of the two conformers. According to this invention it is possible to use single conformers 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 chromatography.

The oximes required for the reaction are prepared in general analogy to known methods, for example by reacting compounds containing reactive methylene groups, such as benzylcyanide 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 described, 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 "Organic Synthesis", 1979, 59, Oximes can also be obtained e.g. by reacting a corresponding carbonyl compound or thiocarbonyl compound with hydroxylamine.

A further preparation method is nitrosation of hydroxyaromatics.

The preparation of sulfonic acid halides 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 E below 10 at 365 nm. 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, characterized by a molar extinction coefficient E 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 E 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 formula la, as defined above, characterized by a molar extinction coefficient e below 10 at 365 nm.

These chemically amplified photoresists preferably have a thickness of more than 2 im.

Also the compositions according to the invention preferably are applied in a thickness of more than 2 Im befor the irradiation.

These resists encompass chemically amplified, negative photoresists which are developable in alkaline medium and having a resist thickness larger than 2 jRm and are sensitive to radia- Veo..

tion in the range from 340 to 390 nanometers, which resists are based on photosensitive .i 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 Rm 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 Rim 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 development 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 -11of 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 molar extinction coefficient E 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 acidsensitive protective groups from a polymer structure, or the cleavage of polymers containing acid-sensitive groups in the polymer backbone. Other applications are, for example, colourchange 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 simple 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 undergo 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 i'o 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 polyimide precursors with acid labile protecting groups which change the solubility during development) can be irradiated 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- -12fonates 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 areas.

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 filmforming 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 polyvinyl acetals or polyvinyl alcohols with polyfunctional acetal derivatives. Under certain conditions, 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-condensation 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 polycondensation of polysiloxanes is described, for example, in J.J. Lebrun, H. Pode, Comprehensive 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-irradiated sections that occurs as a result of the acid-catalysed reaction of the resist material during or after irradiation of the resist may be of two types depending on which further constituents are present in the formulation, or the resist. If the compositions according to the invention 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.

-13- Acid-sensitive components that produce a negative resist are in particular compounds that, when catalysed by acid 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 etherified 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 tetramethoxymethyl 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.

CHOCH CH 2 0OCH 3 N -(CH 2 0CH 3 2 N N N' N O= I 8); *N I II. N N

(CH

3

OCH

2 N N -(CHOCH 3 2

CH

3 0CH 2

CHOCH

0

CH

3 O N.C 0C H (9)

O

0 The concentration of the acid generating compound in general and specifically the concentration 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.

-14- Where appropriate, the negative compositions may additionally comprise a film-forming polymeric 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 disubstituted by C 1 -Cgalkyl, such as m- or p-cresol, the various xylenols, p-tert-butylphenol, p-nonylphenol, p-phenylphenol, resorcinol, bis(4-hydroxyphenyl)methane or 2,2-bis(4-hydroxyphenyl)propane. Also suitable are homo- and copolymers based on ethylenically unsaturated 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 thickness larger than 2 pm which are developable in alkaline medium for a working radiation of a wavelength between 340 and 390 nanometers, 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 sulfonate 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 especially good properties.

It is preferred to use a negative resist comprising N-methoxymethyl melamine or tetramethoxymethylglucoril 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 resist 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 reaction 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 according 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 developable in alkaline medium for a working radiation of a wavelength of 340 to 390 nanometers, comprising a compound of formula I or la, respectively, having a molar extinction coefficient e below 10, and at least one compound which substantially prevents the composition 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 insoluble 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- Sromatic hydroxyl groups, carboxylic acid groups, secondary amino groups and keto or aldehyde groups. These monomeric and polymeric organic compounds before their use as dissolution 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 derivatives 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 -16the 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 C 1

-C

4 alkyl, C 1

-C

4 alkoxy or halogen. Particularly preferred monomeric dissolution inhibitors are bisphenyl types, i.e. compounds of formula ZY wherein each Y is an acid-sen- Ssitive group, such as a phenolic hydroxyl group, which is protected by a suitable acid-sensitive 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:

-SO

2 wherein Ra is hydrogen, methyl or aryl, and Rb is hydrogen or methyl. Particularly preferred divalent radicals are -CH 2

-C(CH

3 2 and C(CH 3 The preferred polymeric dissolution inhibitors are derived from customary phenolic resins, typically from polyvinyl phenols, the hydroxyl groups of which are also blocked in a manner consistent with the above description. Dissolution inhibitors carrying protective 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. Clecak 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 Chemically Amplified Resists", Journal of Photopolymer Science and Technology, Vol. 1990, p. 301-304. The dissolution inhibitors carrying protective groups can be prepared by standard 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 tertbutyloxy groups are disclosed in EP 0329610, inhibitors carrying protective groups of the tetrahydrofuranyl and tetrahydropyranyl type group are described, inter alia, by N. Hayashi, -17- 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-dihydrofurans 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 binder and, where appropriate, a monomeric dissolution inhibitor.

Examples of acid-inert binders are novolaks, especially those based on m- or p-cresol and formaldehyde, also poly(p-hydroxystyrene), poly(p-hydroxy-a-methylstyrene) arid copo- S'lymers of p-hydroxystyrene, p-hydroxy-a-methylstyrene and acetoxystyrene.

Examples of polymeric dissolution inhibitors are novolaks, especially those based on mor p-cresol and formaldehyde, poly(p-hydroxystyrene), poly(p-hydroxy-a-methylstyrene), copolymers 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 .o 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)oxyi'o* °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 change 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 corresponding 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, trimethylsilylmethyl (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 coefficient E 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 removed 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 E 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.

S: Another embodiment is a positive resist comprising from 40 to 90 by weight of an acid-inert 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 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 components 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 material dissolves in a suitable developer medium. This inhibiting effect can be cancelled by irradiating 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 E below 10, respectively, and a binder -19which 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 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 negativb resists in many applications, especially because of their better resolution. There is, however, also interest in producing a negative image using the positive resist mechanism, in order to combine the advantages of the high degree of resolution of the positive resist with the properties of the ne- :°oooo Sgative resist. This can be achieved by introducing a so-called image-reversal step as described, for example, in EP 361906. For this purpose, the image-wise irradiated resist material 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 developed in the customary manner.

In addition to the cited components, it is also possible to add compounds which accelerate or S"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 a ,ooe 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 additives are flow control agents, wetting agents, adhesives, thixotropic agents, colourants, pigments, 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 it is possible 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, dialkoxyacetophenone, a-hydroxyacetophenone or a-aminoacetophenone, 4-aroyl-1,3-dioxolane, benzoin alkyl ethers and benzil ketals, phenylglyoxalic esters and derivatives thereof, dimeric phenylglyoxalic 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-dodecylbenzoyl)-1 -hydroxy-1-methylethane, 1-(4-isopropylbenzoyl)-1 -hydroxy-1-methyl-ethane, 1-benzoyl-1-hydroxy-1 -methylethane, 1-[4(2-hydroxyethoxy)benzoyl]-1 -hydroxy-1 -methylethane, 1- S [4(acrylolyoxyethoxy)benzoyl]-l -hydroxy-1 -methylethane, diphenyl ketone, phenyl-1hydroxycyclohexyl ketone, (4-morpholinobenzoyl)-1 -benzyl-1 -dimethylaminopropane, 1-(3,4dimethoxyphenyl)-2-benzyl-2-dimethylaminobutan-1 -one, (4-methylthiobenzoyl)-1 -methyl-lmorpholinoethane, benzil dimethyl ketal, bis(cyclopentadienyl)-bis(2,6-difluoro-3pyrrylphenyl)titanium, trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)- (2,4,4-trimethyl-pentyl)phosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,4-dipentoxyphenylphosphine 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 hexaarylbisimidazolyl compounds.

Further examples of additional photoinitiators are also cationic photoinitiators, typically peroxide 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 cyclopentadienyl-arene-iron(l I)-complex salts, typically (T 6 -isopropylbenzol)(r 5 -cyclopentadienyl)-iron-llhexafluorophosphate.

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- -21tyrolactone, ethyl methyl ketone, 2-ethoxyethanol, 2-ethoxyethyl acetate and, in particular, 1methoxy-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 composition and on the coating method.

The solution is uniformly applied to a substrate by means of known coating methods, for example by spin-coating, immersion, knife coating, curtain coating techniques, brush application, 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 (laminating).

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 Im to more than 100 lm but in the conntext of the present invention particularly values 2 lam are preferred. Especially preferred are coating thicknesses from 2 lm to 100 im, for example 2.5 lam to 60 lam or 2.5 lim to 20 jim.

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- :oo. 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 recording 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 circuits, as preferred, the layer thicknesses are typically from 2 to 30 im, preferably from 2 to gm. 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 jim, preferably from 2 to 7 Im.

-22- The compositions according to the invention are also outstandingly suitable as coating compositions 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 Al, 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, drying temperatures are in the range from 80 to 140 0

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 predetermined 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 range of the resist, for example between 340 to 390 nanometers. Both point sources and planiform projectors (arrays of reflector lamps) are suitable. Examples are: carbon arc lamps, xenon arc lamps, medium pressure, high pressure and low pressure mercury lamps, optionally 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- -23beam 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 wavelength 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 i 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 accelerate 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 1600C are preferably used. The period of .o *time depends on the heating method and, if necessary, the optimum period can be determined 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 convection oven is used.

The coating is then developed, the portions of the coating that, after irradiation, are more soluble 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 process 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 metal-free bases, such as ammonia or amines, for example ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyl diethylamine, alkanolamines, for example dimethyl ethanolamine, triethanolamine, quaternary ammonium hydroxides, for example -24tetramethylammonium 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 coating a substrate with a composition as described above, 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 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 recording 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 E 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 production 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-phenylacetonitrile, a-(methanesulfoniumoxyimino)-4-methyl-phenylacetonitrile, or a-(4-toluenesulfoniumoxyimino)-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 sulfonium oxyimino)-3,4-dimethyl-phenylacetonitrile (having an e of 4.1 in a tetrahydrofuran solution 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 pm.

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 0 C for 90 seconds.

The resulting formulation is subjected to a development treatment in a 2.38 by weight aqueous solution of tetramethylammonium hydroxide for 60 seconds, afterwards is washed with water and dried by air.

The photosensitivity of line-and-space of 2 pm 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/cm 2 (energy).

Further, a resist layer patterned in a line-and-space pattern of 2 pm 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 rectangular form standing perpendicularly to the substrate. The relative width of the line prepared -26by varying the exposure dose between 0.8 and 1.2 times against the photosensitivity obtained 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 E of 0.35 in a tetrahydrofuran solution at 365 nm) are used.

Following the same conditions as described in Example 1 the resulting photosensitivity is 300 mJ/cm 2 The cross sectional profile of the resist layer of 2 Lm 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 E of 0.28 in a tetrahydrofuran solution at 365 nm) are used.

Following the same conditions as described in Example 1 the resulting photosensitivity is 500 mJ/cm 2 The cross sectional profile of the resist layer of 2 pim 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/cm 2 and a slope of 0.72.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims (16)

1. A 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 an acid under the exposure of light of a wavelength of 240 to 390 nm and having a molar extinction coefficient e below 10 at i- line (365 nm).

2. A composition according to claim 1, comprising as component a compound comprising a structural unit of formula I SC= N O SO and wherein the compounds are characterized by a molar extinction coefficient e below 10 at 365 nm.

3. A composition according to claim 1, comprising as component a compound of formula la NC SR, C=N-O-SO 2 -R, R 2 (la) wherein R RR R 1 R 2 R 3 R 4 and Rs independently of one another are hydrogen, unsubstituted or halogen- substituted C 1 -C 1 2 alkyl; or R 1 R 2 R 3 R 4 and Rs are halogen; R 6 is unsubstituted or halogen-substituted Cl-C 18 alkyl, phenyl-C-C 3 alkyl, 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 1 -C 4 haloalkyl, CN, NO 2 C 1 -C 1 6 alkyl, phenyl, ORIo, COOR 9 -O(CO)-Ci-C 4 alkyl, SO 2 0R 9 and/or by NR 7 R; R7 and Re independently of each other are hydrogen or C 1 -C 1 2 alkyl, which is unsubstituted or substituted by OH, C 1 -C 4 alkoxy, Ci-C 1 2 alkylsulfonyl, phenylsulfonyl, (4-methylphenyl)- -28- sulfonyl and/or by C 1 -C 6 alkanoyl; or R 7 and Re are C 2 -C 12 alkyl, which is interrupted by and which is unsubstituted or substituted by OH, C 1 -C 4 alkoxy, C 1 -C 1 2 alkylsulfonyl, phenylsulfonyl, (4-methylphenyl)sulfonyl and/or by C 1 -C 6 alkanoyl; or R 7 and Re are phenyl, C 2 -C 6 alkanoyl, benzoyl, Ci-C 6 alkylsulfonyl, phenylsulfonyl, (4-methylphenyl)- sulfonyl, naphthylsulfonyl, anthracylsulfonyl or phenanthrylsulfonyl; or R 7 and Re, together with the nitrogen atom to which they are linked, form a 6- or 7-membered ring which may be interrupted by or by -NR 11 R 9 is Ci-C 1 2 alkyl which is unsubstituted or substituted by OH and/or by Cl-C 4 alkoxy, or R 9 is C 2 -C 1 2 alkyl which is interrupted by and which is unsubstituted or substituted by OH and/or by Ci-C 4 alkoxy; Rio is hydrogen; C 1 -C 12 alkyl which is unsubstituted or substituted by phenyl, OH, Ci-C 1 2 alkoxy, Cs-C 1 2 alkylsulfonyl, phenylsulfonyl, (4-methylphenyl)sulfonyl and/or by C2-C6- alkanoyl; or Rio is C2-C 12 alkyl which is interrupted by and which is unsubstituted or substituted by phenyl, OH, Ci-C 1 2 alkoxy, C 1 -C 12 alkylsulfonyl, phenylsulfonyl, (4-methyl- phenyl)sulfonyl and/or by C 2 -C 6 alkanoyl; or Rio is phenyl; R 11 is hydrogen, unsubstituted or OH-substituted C 1 -C 12 alkyl, or C 2 -C 1 2 alkyl which is interrupted by and wherein the compounds of formula la are characterized by a molar extinction coefficient E 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 E below 10 at 365 nm. o 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 la, as defined in claim 3, characterized by a molar extinction coefficient e below 10 at 365 nm.

6. A chemically amplified photoresist according to claim 4 or 5 having a thickness of more than 2 1m.

7. A chemically amplified negative photoresist comprising a compound of formula la, having a molar extinction coefficient e below 10, which is developable in alkaline medium, having a -29- resist thickness larger than 2 pm 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 pm which is developable in alkaline medium for a working radiation of a wavelength between 340 and 390 nano- meters, comprising an oxime sulfonate of formula la 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 la, having a molar extinction coefficient e below 10, which is developable in alkaline medium, having a resist thickness larger than 2 pm and which is sensitive to radiation in the range from 340 to 390 nanometers. ,ie

10. A positive photoresist comprising a compound of formula la, 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 la. 5*

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 coating a substrate with a composition according to claim 1, irradiating the coating with radiation having a wavelength of 340 to 390 nanometers in a desired pattern, heating the coating to temperatures of 60 to 160 0 C, and removing the more soluble sections of the coating with an aqueous-alkaline developer.

14. Use of a compound of formula I or la, having a molar extinction coefficient E below 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. A process for generating sulfonic acids, wherein a photoacid generator of formula la, having a molar extinction coefficient E 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 la a-(methane sulfonium oxyimino)-3,4-dimethyl-phenylacetonitrile, a- (methanesulfoniumoxyimino)-4-methyl-phenylacetonitrile, or a-(4-toluenesulfoniumoxyimino)- phenylacetonitrile.

17. A composition activateable by light substantially as hereinbefore described with reference to the Examples.

18. A chemically amplified photoresist substantially as hereinbefore described with reference to the drawings. DATED this 16th day of August, 1999 CIBA SPECIALTY CHEMICALS HOLDING INC. By Their Patent Attorneys DAVIES COLLISON CAVE