CA1282627C

CA1282627C - Image reversal negative working photoresist

Info

Publication number: CA1282627C
Application number: CA000515742A
Authority: CA
Inventors: Dana Durham; Mark A. Spak; Donald Mammato; Sangya Jain
Original assignee: American Hoechst Corp; Hoechst Celanese Corp
Current assignee: CNA Holdings LLC
Priority date: 1985-08-12
Filing date: 1986-08-12
Publication date: 1991-04-09
Anticipated expiration: 2008-04-09
Also published as: EP0212482B1; EP0212482A2; KR950000236B1; DE3662952D1; KR870002479A; JPS6238448A; JPH0772797B2; EP0212482A3; HK71490A; ATE42419T1

Abstract

ABSTRACT

A process for converting a normally positive working photo-sensitive composition to a negative working composition. One forms a composition containing an alkali soluble resin, a 1,2 quinone diazide-4-sulfonyl compound and an acid catalyzed crosslinker in a solvent mixture. After drying and imagewise exposing, the composition is baked and developed to produce a negative image.

Description

6~7 BACKGROUND O~ THE INVENTION

~he present invention relates generally to radiation sensitive photoresist compositions and particularly to compositionS
containing aqueous alkali soluble resins together with naphthoquinone dia~ide sensitizing agents.

It is well known in the art to produce positive photoresist formulations such as those described in United States Patent Nos. 3,666,473, 4,115,128 and 4,I73,470. These include alkali- - -soluble phenol-formaldehyde novolak resins together with light-sensitive materials, usually a substituted naphthoquinone diazide compound. The resins and sensitizers are dissolved in an organic solvent or mixture of solvents and are applied as a thin film or coating to a substrate suitable for the particular application de~sired. `-- '-The resin component of these photoresist formulations is soluble -;:
in aqueous alkaline solutions, but the naphthoquinone sensitizer acts as a dissolution rate inhibitor with respect to the resin.
~pon exposure of selected areas of the coated substrate to actinic radiation, however, the sensitizer undergoes a radiation "~
induced structural transformation and the exposed areas of the coating are rendered more soluble than the unexposed areas. This difference in solubility rates causes the exposed-areas of the photoresist coating to be dlssolved when the substrate is immersed in an alkaline developing solution while the unexposed areas are largely unaffected, thus producing a positive relief pattern on the substrate.

In~most instances, the exposed and developed substrate will be subjected to treatment by a substrate-etchant solution. The photoresist coating protects the coated areas of the substrate from the etchant and thus the etchant is only able to etch the ~X~32~2~7 uncoated areas of the substrate, which in the case of a positive photoresist, correspond to the areas that were exposed to actinic radiation. Thus, an etched pattern can be created on the substrate which corresponds to the pattern on the mask, stencil, -template, etc., that was used to create selective exposure patterns on the coated substrate prior to development.

The relief pattern of the photoresist on the substrate produced ,<, .~:
by the method described above is useful for various applications including as an exposure mask or a pattern such as is employed in the manufacture of miniaturized integrated electronic components. -The properties of a photoresist composition which are important in commercial practice include the photospeed of the resist, development contrast, resist resolution, and resist adhesion.
"'.'' ' Resist resolution refers to the capabilityof a resist system to reproduce the smallest equally spaced line pairs and intervening spaces of a mask which is utilized during exposure with a high degree of image edge acuity in the developed exposed spaces.

.....
In many industrial applications, particularly in the manufacture of minaturized electronic components, a photoresist is required to provide a high degree of resolution for very small line and space widths (on the order of one micron or less).

The ability of a resist to reproduce very small dimension, on the order of a micron or less, is extremely important in the production OL large scale integrated circuits on silicon chips and similar components. Circuit density on such a chip can only be.increased, assuming photolithography techniques are utilized, by increasing the resolution capabilities of the resist.

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Photoresists are generally categorized as being either positive working or negative working. In a negative working resist composition, the imagewise light strucX areas harden and form the image areas of the resist after removal of the unexposed areas with a developer. In a positive working resist the unexposed areas are the image areas. The light struck parts are rendered soluble in aqueous alkali developers.
While negative resists are the most widely used for industrial production o printed circuit boards, positive resists are cap-able of much finer resolution and smaller imaging geometries.Hence positive resists are the choice for the manufacture of densely packed integrated circuits.
In many commercial applications, it is desirable to convert a high resolution quinone diazide type positive resist for a negative working application.
There is interest in the field of image reversal be-cause of the utility of this process in practical device manu-facturing. Among the practical aspects of image reversal are the elimination of the need for a dual set of complementary masks to do both positive and negative imaging, greater resolu-tion and process latitude than with positive imaging alone, re-duction in standing wave effects, and higher thermal stability.
In this regard, several methods have been suggested for such image reversal. See for example: "Image Reversal-. The Production of a Negatiue Image in a Positive Photoresist" by S.A. MacDonald et.al. p.114, IBM Research Disclosure, 1982;
"Image Reversal of Positive" Photoresist". A New Tool for .
Advancing Integrated Circult Fabrication by E. Alling et.al., Journal of the Society of Photo-Imaging Engineers, Vol 539, p~

3~ 194, 1985; M.V. Buzuev et.al. "Producing a_N_gative Image on a Positive Photoresist'i SU 1,109,708; German Patent DE 252 9054, C2, 1975, Assigned to H. Moritz and G. Paal, ~ ;

Making a Negative Image; U.S. 4,104,070, U.S. 4,576,901 and U.S. 4,5S1,321.
Each of these disclosures suffer from several draw-backs. A major disadvantage of current image reversal processes is the need for an additional processing step which involves ~reatment with either salt forming compounds or high energy exposure sources such as electron beams or requires an additional exposure step with actinic light. The present in-vention provides a mechanism which involves the formation of a catalytic amount of a radiation generated acid which cross-links the resin in the exposed region.
The invention provides a unique chemical composition, which when processed in a slightly modified manner to the usual and customary method of lithographic processing, yields a totally unexpected negative, reversed tone image from an other-wise expected positive type photosensitizer.
Among the advantages realized by this highly desir-able result are improvement in the relationship between exposure energy and resulting line width, improved process latitude, improvement in developed image resolution, substan-tial elimination of reflective notching, enhanced photo-sensitivity, improved thermal stability of the resulting image, and improved adhesion between the photoresist and commonly used substrates.
SUMMARY OF THÆ INVENTION
The invention provides a process for preparing a negative image of a positive working photographic element which comprises in order:
a) forming a composition which comprises i) from about 1% to about 25% based on the weight of the solid parts of the composition of a photosensitive compound having the formula ~2826~7 4 ~
~S~ ORl wherein R1 = 1,2 benzoquinone-2-diazide-4-sulfonyl;
1,2 naphthoquinone-2-diazide-4-sulfonyl;

or 1,2 anthraquinone-2-diazide-4-sulfonyl R~ - H, Rs, OR6 or C - R7 R3 = H, Rs, OR6 or C - R7 R4 = ~, Rs, OR6 or C - R7 R6 = H, alkyl, aryl, aralkyl or R
Rs,R7 = alkyl, aryl or aralkyl ii) from about 75% to about 99% based on the weight of the solid parts of the composition of a novolak, and/or polyvinyl phenol resin, especially poly-p-vinyl phenol resin; and iii~ from about 0.5% to about 20% based on the weight of the solid parts of the composition of a cross linking compound which, when in the presence of that amount and strength of the acid generated ~LZ8X~Z~7 _ when said diazide is exposed to actinic radiation, is capable of crosslinking said resin under the application of the heating conditions of step (e); and iv) sufficient solvent to dissolve the foregoing composition components; and b~ coating said composition on a suitable substrate; and c) heating said coated substrate at a temperature of from about 20C to about 100C until substantially all of ~~
said solvent is dried off; and d) imagewise exposing said composition to actinic radiation; and e) heating said coated substrate at a temperature of at least about 95C to about 160C for from about 10 ! ~'.
seconds or more to crosslink said resin; and ) removing the unexposed non-image areas of said composition with a suitable developer.

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D~TAILED DESCRIPTION OF THE PREFERR_D EMBODIMENT

As a first step in the production of the photographic element of the present invention, one coats and dries the foregoing photosensitive composition on a suitable substrate.
The composition contains a solvent, crosslinking agent, binding resin and a 1,2 quinone diazide-4-sulfonyl group containing photosensitizer. The binding resins include the classes known as the novolaks, ployvinyl phenols and especially polyparavinyl phenols.
The production of novolak resins, which m~y be used for preparing photosensitive compositions, is well known in the art. A procedure for their manufacture is described in ~hemistrY and APPlication of Phenolic Resins, Knop A. and Scheib W., Springer Verlag, New York, 1979 in Chapter 4.
Polyvinyl phenols and especially polyparavinyl phenols are taught in U.S. 3,869,292 and 4,439,516. Similarly, the use of o-quinone diazides is well known to the skilled artisan as demonstrated by Liqht Sensitive SYstems, Kosar, J ; John Wiley ~0 & Sons, New York, 1965 in Chapter 7.4. These sensitizers which comprise a componen~ of the present resist compositions of the present invention are preferably selected from the group of substituted naphthoquinone diazide sensitizers which are conventionally used in the art in positive photoreslst formulatlons. Such sensitizlng compounds are disclosed, for example, in United States Letters Patent Nos. 2,797,213;
3,106,465; 3,148,983; 3,130,047; 3,201,329, 3,785,825; and 3,802,885.
The photosensitizer is a 1,2 quinone diazide-4-sulfonic acid ester of phenolic derivative. It presentlyappears that the number of fused rings is not important for ~Z~32~iZ7 this invention b~lt the position of the sulfonyl group is important. That is, one may 8a ' ~28~27 use benzoquinones, naphthoquinones or anthraquinones as long as the oxygen is in the 1 position, diazo i5 in the 2 po~ition and the sulfonyl group is in the 4 position. Likew.ise the phenolic member to which it is attached does not appear to be important.
For example it can be cumylphenol derivative as taught in UOS~
3,640,992 or it can be a mono-, di-, or tri-hydroxyphenyl alkyl ketone or benzophenone as shown in U.S. 4,499,171.
As a generalized formula, the quinone diazides of the present invention may be represented by:

1 0 1~

wherein R1 = 1,2 benzoquinone-2-diazide-4-sulfonyl;
1,2 naphthoquinone-2-diazide-4-sulfonyl;
or 1,2 anthraquinone-2-diaæide-4-sulfonyl R2 = H, Rs, OR6 or C - R7 R3 = H, Rs, OR6 or C - R7 ll R4 = H, Rs, OR6 or C - R7 R6 = H, alkyl, aryl, aralkyl or R1 R5,R7 = alkyl, aryl or aralkyl Useful photosensitizers include (1,2)naphthoquinone-diazide-4-sulfonyl chloride, condensed with phenolic compounds such as hydroxy benzophenones especially trihydroxybenzophenone and more particularly 2,3,4 trihydroxybenzophenone; 2,3,4 tri-30 hydroxyphenyl pentyl ketone 1,2 naphthoquinone-2-diazide-4-sul-fonic acid trisester or other alkyl phenones; 2,3,4 trihydroxy-3'-methoxy benzophenone 1,2 naphthoquinone-2-diazide-.~, _ g _ ~2BZ~27 4-sulfonic acid trisester; 2,3,4 trihydroxy-3'-methyl benzophenone 1,2 naphthoquinone-2~diazide-4-sulfonic acid trisester; and 2,3,4 trihydroxybenzophenone 1,2 napthoquinone diazide 4 sulfonic acid trisester.
The cross-linking compound is a compound, which when in the presence of that amount and strength of the acid generated when the diazide is exposed to actinic radiation, is capable of cross-linking the foregoing novolak, polyvinyl phenol or poly-p-vinyl phenol resin. This occurs upon the application of sufficient heat to diffuse the acid to the cross-linking component but less heat than will decompose the diazide. The general class of such compounds are those capable of forming a carbonium ion under the foregoing acid and heat conditions.

~ .

The crosslinking compound is a compound having the gene-ral formula ~ R10-CHR3)n-A-(CHR3~0R2)m wherein A is B or B-Y-B and B is a substituted or unsubstituted mononuclear or fused polynuclear aromatic hydrocarbon or an oxygen- or sulfur- containing heterocy-clic aromatic compound Y is a single bond, Cl to C~ -alkylene or -alkylene dioxy, which chain can be interrupted by -O-, -S-, -S02-, -CO-, -C02-, -0-C02-, CONH2, or phenylene dioxy, Rl and R2 are the same or different and represent hydrogen, Cl to C6-alkyl, -cycloalkyl, substi-tuted or unsubstituted aryl, aralkyl or acyl, R3 is hydrogen~ Cl to C4-alkyl or substituted or unsubstituted phenyl, - .
n means 1 to 3 and m means O to 3, under the provision that n + m is at least 2.
Suitable representatives of these crosslinking compounds are, for example:
1,4-bis-hydroxymethyl-benzene, 1,3-bis-hydroxymethyl-benzene, 1,4-bis-methoxymethyl-benzene, 1,5-bis-acetoxymethyl-naphthalene, 1,4-bis-hydroxymethyl-naphthalene, 9,10-bis-methoxymethyl-anthracene, 2r5-bis-(hydroxymethyl)-furan~

- 10 a -6~

~,5-bis-ethoxymethyl-thiophene, bis-methoxymethyl-diphenylene-oxide, bis-methoxymethyl-dimethyldiphenylene-oxide, 2,6-bis-hydroxymethyl-naphthalene, 1,4-bis-l~-hydroxymethyl)-benzene, 1 r 4-bis~ hydroxybenzyl)-benzene, 4,6-dimethyl-1,3-bis-hydroxymethyl-benzene, 2,5-dimethyl-1,4-bis-hydroxymethyl-benzene, 2,4,6-trimethyl-1,3-bis-hydroxymethyl-benzene, 2,4,6-trimethyl-1,3,5-tris-methoxymethyl-benzene, 2,3,5,6-tetramethyl-1,4-bis-acetoxymethyl-benzene, 2,4,5,6-tetramethyl-1,3-bis-ethoxymethyl-benzene, 4,4'-bis-acetoxymethyl-diphenylmethane, 4,4'-bis-methoxymethyl-diphenyl, 2-methyl-1,5-bis-acetoxymethyl-naphthalene, 2-ethyl-9,10-bis-methoxymethyl-anthracene, 4,6-diisopropyl,1,3-bis-hydroxymethyl-benzene, 4,6-diisopropyl-1,3-bis-methoxymethyl-benzene, 4,4'-bis-acetoxymethyl-diphenyl sulfone, 4,4'-bis-methoxymethyl-benzophenone, 2,6-bis-hydroxymethyl-4-chlorophenol, 2,6-bis-hydroxymethyl-4-methyl-anisole, 1,3-bis-(3-hydroxymethyl-phenoxy)-propane, 1,3-dihydroxymethyl-2-methoxy-5-n-hexyl-benzene, 1,3-dihydroxymethyl-2-ethoxy-5-ethyl-benzene, 1,3-dihydroxymethyl-2-benzyloxy-5-methoxycarbonyl-benzene, 1,3-dihydroxymethyl-2-methoxy-5-bromobenzene, - 10 b -~ 6~

1,3-dihydroxymethyl-2-methoxy-5-cumyl~benzene, 1,3-dihydroxymethyl-2-ethoxy-5-methylmercapto-benzene, 1,3-dihydroxymethyl-2-ethoxy-5-phenoxy-benzene, 1,3-dihydroxymethyl-2,5-diethoxy-benzene, 1,3-dihydroxymethyl-2-methoxy-5-benzyl-benzene, 1,3-dimethoxymethyl-2-methoxy S-fluorobenzene, 1,3-dimethoxymethyl-2-ethoxy-5-methoxy-benzene, 1,3-dimethoxymethyl-2-methoxy-5-phenyl-benzene, bis-(2-(4-hydroxymethyl phenoxy)-ethyl¦-ether, 1,3-dimethoxymethyl-2-etho~y-5-bromobenzene, 1,3-diacetoxymethyl-2-ethoxy-5-tert.-butyl-benzene, 1,3-diacetoxymethyl-2-methoxy-5-phenylmercapto-benzene, 1,3-diacetoxymethyl-2-methoxy-5-chlorobenzene, 1,3-diacetoxymethyl-2,5-dimethoxy-benzene, 1,3-bis-~2-methyl-4-benzyl-6-hydroxymethyl-phenoxy)-propane, bis-(3,5-hydroxymethyl-4-hydroxyphenyl)-methane, dihydroxymethyl-hydroquinone dimethyl ether, 4-methoxy-3,5-bis-hydroxymethyl-diphenyl ether, bis-(4-ethoxy-5-methyl-3-hydroxymethyl-phenyl)-sulfone, 4,4'-bis-hydroxymethyl-diphenyl ether, 4,4'-bis-acetoxymethyl-diphenyl ether, 4,4'-bis-methoxymethyl-diphenyl e~her, ~'~bis-ethoxymethyl-diphenyl ether, 2,4'-bis-methoxymethyl-diphenyl ether, 2,4,4'-tris-methoxymethyl-diphenyl ether, 2,4,2'-tris-methoxymethyl-diphenyl ether, 2,4,2',4'-tetrakis-methoxymethyl-diphenyl ether, bis-methoxymethyl-4,4'-dimethyl-diphenyl ether, - l,~c -bis-methoxymethyl-2,4-dimethoxy-5-methyl-diphenyl ether, bis-methoxyme~hyl-3,3'-dimethyl-diphenyl sulfide, bis-methoxymethyl-2,4'-dimethoxy-diphenyl sulfide, 2,2'-bis-(4,hydroxymethyl-phenoxy)-dlethyl ether, 2,2'-dimethyl-~,4'-bis-hydroxymethyl-diphenyl ether, 1,3-bis-(4-methoxymethyl-phenoxy~-benzene, 1,3-bis-(4-methoxyme~hyl-phenoxy)-propane, 4,4'-bis-methoxymethyl-diphenyl sulfide, 2,2-bis-(4-methoxymethyl-phenyl)-propane, 4,4'-bis-phenoxymethyl-diphenyl ether, bis-methoxymethyl-4-phenoxydiphenyl sulfide, bis-methoxymethyl-2-isopropyl-5-methyl-diphenyl ether, bis-methoxymethyl-3-bromo-4-methoxy-diphenyl ether, bis-methoxymethyl-4-nitro-diphenyl ether, and 2,2'-bis-l3,5-hydroxymethyl-4-hydroxyphenyl)-propane.
A preferred compound or mixture of compounds is selected from the group of dimethyl para-cresol, 4,4'bis-methoxy-methyl diphenyl ether r epoxy cresol novolak resin, 2,5-bis-(hydroxymethyl)-furan, 2,5-bis(ethoxy-methyl)-thiophene, bis(3,5-hydroxymethyl-4-hydroxyphenyl)-methane, 4,4'bis-acetoxymethyl-diphenyl ether, 1,4-bis-(~hydroxybenzyl)-benzene, 2,6-bls-hydroxymethyl-4-methyl-anisole and 2,2 bis-(3,5-hydroxymethyl-4-hdyroxy-phenyl)-propane. The preferred com-pounds are dimethylol paracrescol as described in U.S. 4,404,272, 4,4'-bis-methoxymethyl diphenyl ether, and epoxy cresol novolak resin.

- 10d-8~7 The epoxy cresol novolak resins have the general formula O
~0 / \ 0--C~12--CH--CH2 O-CH~-CH-~H2 O--C112--CH--CH2 ~-- C~2 --+~ C~2 ~

where n = 1-10 The photosensitive composition is formed by blending the ingredients in a suitable solvent composition. In the preferred embodiment the resin is preferably present in the overall composition in an amount of from about 75% to about 9g% based on the weight of the solid, i.e. non-solvent parts of tile ~`
composition. A more preferred range of resin would be from about B0~ to about 90% and most preferably from about 82~ to about 85 by weight of the solid composition parts. The diazide is preferably present in an amount ranging from about 1% to about 2S~ based on the weight of the solid, i.e., non-solvent parts of the composition. A more preferred range of the diazide would be ~rom about 1~ to about 2~% and more preferably from about 10~ to about 18% by weight of the solid composition parts. The crosslinker is preferably present in an amount ranging from about 0.5% to about 20% based on the weight of the solid, i.e.
non-solvent parts of the composition. A more preferred range ~ould be from about 1% to about 10% and most preferably from about 3~ to about 6% by weigh~ of the solid composi~ion parts.
In manufacturing the composition the resin, crosslinker and diazide are mixed with such solvents as the propylene glycol alkyl ether acetate, butyl acetate, xylene, ethylene glycol monoethyl ether acetate, and propylene glycol rnethyl ether acetate, among others.
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X6'~7 Additives such as colorants, dyes, anti-striation agents, leveling agents, plasticizers, adhesion promoters, speed enhancers, solvents and such surfactants as non-ionic surfactants may be added to the solution o~ resin, sensitizer, cross-linker and solvent before the solution is coated onto a substrate.
Examples of dye additives that may be used together with the photoresist compositions of the present invention include Methyl Violet 2B (C.I. No. 42535), Crystal Violet ~.I. 42555), Malachite Green (C.I. No. 42000), Victoria Blue B (C.I. No.
1Q 44045) and Neutral Red (C.I. No. 50040) at one to ten percent weight levels, based on the combined ~7eight of the solid parts of the composition. The dye additives help provide increased resolution by inhibiting back scattering of light o~f the sub-strate.
Anti-striation agents may be used up to five percent weight level, based on the combined weight of solids.
Plasticizers which may be used include, for example, phosphoric acid tri-(~-chloroethyl)-ester; stearic acid; di-camphor; polypropylene; acetal resins; phenoxy resins; and alkyl ~0 resins at one to ten percent weigh~ levels, based on the combined weight of solids. The plasticizer additives improve the coating properties of the material and enable the application of a ~ilm that is smooth and of uniform thickness ~o the substrate.
Adhesion promoters which may be used include, for example, ~-(3,4-epoxy-cyclohexyl)-ethyltrimethoxysilane;
pentamethyldisilane-methyl methacrylate; vinyltrichlorosilane;
and ~-amino-propyl triethoxysilane up to a 4 percent weight level, based on the combined weight of solids.
Speed enhancers that may be used include, for example, picric acid, nicotinic acid or nitrocinnamic acid at a weight level of up to 20 percent, based on the combined weight of resin and solids. These enhancers tend to increase the solubility of '~ ' .

Z~7 the photoresist coating in both the exposed and unexposed areas, and thus they are used in applications when speed of development is the overriding consideration even though some degree of contrast may be sacrificed; i.e., while the exposed areas of the photoresist coating will be dissolved more quickly by the developer, the speed enhancers will also cause a larger loss of photoresist coating from the unexposed areas.
The coatiny solvents may be present in the overall com-position in an amount of up to 95~ by weight of the solids in the composition.
Non-ionic surfactants that may be used include, for ex-ample, nonylphenoxy poly(ethyleneoxy~ ethanol; octylphenoxy-(ethyleneoxy) ethanol; and dinonyl phenoxy poly (ethyleneoxy) ethanol at up ~o 10 percent weight, based on the combined weight of solids.
The prepared resist solution can be applied to a sub-strate by any conventional method used in the photoresist art, including dipping, spraying, whirling and spin coating. When spin coating, for example, the resist solution can be adjusted as ~0 to the percentage of solids content in order to provide coating of the desired thickness given the type of spinnlng equipment utilized and the amount of time allowed for the spinning process.
Suitable substrates include silicon, aluminum or polymeric resins, silicon dioxide, doped silicon dioxide, silicon nitride, polysilicon, tantalum, copper, ceramics and aluminium/copper mix-tures.
The photoresist coatings produced by the above des-cribed procedure are particularly suitable for application to thermally oxidized silicon wafers such as are utilized in the production of microprocessors and other miniaturized integrated circuit components. An aluminum/aluminum oxide wafer can be used as well. The substrate may also comprise various polymeric .

~ 28~6~7 resins especially transparent polymers such as polyesters.
After the resist composition solution is coated onto the su~strate, the substrate is temperature treated at appro~i-mately 20 to 100~C. This temperature treatment is selected in order to reduce and control the concentration of residual sol-vents in the photoresist while not causing substantial thermal degradation o~ the photosensitizer. In general one desires to minimize the concentration of solvents and thus this first temperature treatment is conducted until substantially all of the solvents have evaporated and a thin coating of photoresist com-position, on the order of a micron in thickness, remains on the substrate. This treatment is normally conducted at temperatures in the range of from about 20C to about 100C. In a preferred embodiment the temperature is conducted at from about 50C to about 90C. A more preferred range is from about 70C to about 90C. This treament is conducted until the rate of change of solvent removal becomes relatively insignificant. The tempera-ture and time selection depends on the resist properties desired by the user as well as equipment used and commercially desired coating times. Commercially acceptable treatment times for hot plate treatment are those up to about 3 minutes, more preferably up to about 1 minute. In one example, a 30 second treatment at 90 is useful. The coating substrate can then be exposed to actinic radiation, especially ultraviolet radiation, in any desired pattern, produced by use of suitable masks, negatives, stencils, templates, etc. in a manner well known to the ski]led artisan.

-V~6~7 The resist is then subjected to a second bakiny or heat treatment after exposure of from about 95C to about 160C, pre-~erably 95C to 150C, more preferably 112C to 120C. This heating treatment may be conducted with a hot plate system for from about 10 seconds to the time necessary to cross-link the resin. This normally ranges from about 10 seconds to 90 seconds, more preferably from about 30 seconds to about 90 seconds and most preferably from 15 to 45 seconds. Durations for longer than 90 seconds are possible but do not generally provide any additional benefit. The time selected depends on the choice of composition components and the substrate used. Heating diffuses the generated acid to the cross-linking component. The baking treatment also converts the diazide to a carboxylic acid containing compound, for example indene carboxylic acid, which is soluble in aqueous alkali solutions.
The selection of the first and second heat treatment temperatures and first and second heat treatment times may be selected and op~imized by the properties which are desired by the end user. If necessary, the resist can be subjected to an addi-tional exposure to actinic radiation without the photomask after the second heat treatment. The exposed resist-coated substrates are next substantially immersed in a suitable developing solu-tion. The solution is preferably agitated~ for example, by nitrogen burst agitation. The substrates are allowed to remain in the developer until all, or substantially all, of the resist coating has dissolved from the unexposed areas. Suitable devel-opers include aqueous alkaline solutions such as those including sodium hydroxide, and tetramethyl ammonium hydroxide as are well known in the art.
After removal of the coated wafers from the developing solution, an optional post-development heat treatment or bake may be employed to increase the coating 16 adhesion and chemical .

~28Z6~7 resistance to etching solutions and other substances. The post-development heat treatment can comprise the oven baking of the coating and substrate below the coating's softening point. In ind~strial applications, particularly in the manufacture of microcircuitry units on silicon/silicon dioxide-type substrates, the developed substrates may be treated with a buffered, hydro-fluoric acid base etching solution. The resist compositions of the present invention are resistant to acid-base etching solu-tions and provide effective protection for the exposed resist-coating areas of the substrate.
The following specific examples will provide detailed illustrations of the methods of producing and utilizing composi-tions of the present invention. These examples are not intended, however, to limit or restrict the scope of the invention in any way and should not be construed as providing conditions, para-meters or values which must be utilized exclusively in order to practice the present invention.
The following non-limiting examples serve to illustrate the invention:
Exam~le 1 The photoresist is made up of a solution containing, 5%
of solids o~ dimethylol para-cresol, 6% of solids of 2,3,4-trihydroxy-3'~methyl benzophenone 1,2-naphthoquinone-2-diazide-4-sulfonic acid trisester and 89% of solids of cresol novolac resin in propylene glycol monomethyl ether acetate.
Using this formulation silicon wafers are coated at 4,000 rpm and then soft-baked in a vented convection oven at 90C
for 30 minutes. Actinic exposure is applied using the Perkin Elmer 220 Micralign aligner through a glass photomask containing a resolution test pattern. Using aperature #4, the scan speeds are varied between 200 and 400 arbitrary energy units. These different scan speeds (each scan speed represents a different iX7 experiment) corresponds to between 20 and 10 mJ/cm2 repsec-tively as determined by an OAI radiometer ~or wavelengths between 365 and 436 nm. The photomask consists of a resolution test pattern where single line and equal line and spaces are repre-sented. The wid~h of these features varies between 1.0 and 3.0 ~m in Q.25 ~m increments. After exposure the wafers are hard baked sequentially on a MTI Inc. hot plate at temperatures ranging from 110C to 150C for up to 60 seconds. A relief image is now observable when the wafers are placed under an optical microscope with monochromatic 520 nm illumination.
After developing the exposed and hard baked wafers in AZ 433 MIF Developer available from the AZ Photoresists Group of American Hoechst Corporation, Somerville, New Jersey (a 0.33N
solution of tetramethylamMonium hydroxide) in an immersion mode process for 3 minutes with slight agitation, the wafers are DI(deionized) water rinsed and spin dryed. If the wafers are now examined using a scanning electron microscope at 10,000 magnifi-cation, 1 ~m single spaces and larger geometries are clearly seen to be completely opened.
Example 2 The photoresist is made up of a solution containing, 5%
of solids of dimethylol para-cresol, 6% of solids of 2,3,4 trihydroxy-3'-methoxy benzophenone 1,2 naphthoquinone-2-diazide-4-sulfonic acid trisester and 89% of solids of cresol novolac resin in propylene glycol monomethyl ether acetate.
Using this formulation silicon wafers are coated at 4,000 rmp and then soft-baked in a vented convection oven at 90C
for 30 minutes. Actinic exposure i5 applied using the Perkin Elmer 220 Micralign aligner through a glass photomask containing a resolution test pattern. Using aperature #4, the scan speeds are varied between 200 and 400 arbitrary energy units. These different scan speeds (each scan speed represents a different '~

1~8Z6Z~

experiment) corresponds to between 20 and 10 mJ/cm2 respec-tively as determined by an OAI radiometer for wavelengths between 365 and 436 nm. The photomask consists of a resolution test pattern where single line and equal line and spaces are represented. The width of these features varies between 1.0 and 3.0 ~m in 0.25 ~m increments. After exposure the wafers are hard baked sequentially on a MTI Inc. hot plate at temperatures ranging from 110C to 150~C for up to 60 seconds. A relief image is now observable when the wafers are placed under an optical microscope with monochromatic 520 nm illumination.
After developing the exposed and hard baked wafers in AZ 433 MIF Developer available from the AZ Photoresists Group of American Hoechst Corporation, Somerville, New Jersey (a 0.33N
solution of tetramethylammonium hydroxide) in an immersion mode process for 3 minutes with slight agitation, the wafers are DI
water rinsed and spin dryed. If the wafers are now examined using a scanning electron microscope at 10,000 magnification, 1 ~m single spaces and larger geometries are clearly seen to be completely opened.
Example 3 The photoresist is made up of a solution containing, 5%
of solids of dimethylol para-cresol, 6% of solids of 2,3,4 tri-hydroxy phenyl pentyl ketone 1,2 naphthoquinone-2-diazide-4-sulfonic acid trisester and 89% of solids of cresol novolac resin in propylene glycol monomethyl ether acetate.
Using this formulation silicon wafers are coated at 4,000 rpm and then soft-baked in a vented convection oven at 90C
for 30 minutes. Actinic exposure is applied using -the Perkin Elmer 220 Micralign aligner through a glass photomask containing ~0 a resolution test pattern. Using aperature #4, the scan speeds are varied between 200 and 400 arbitrary energy units. These different scan speeds (each scan speed represents a different .

8~6'~:7 experiment) corresponds to between 20 and 10 mJ/cm2 respec-tively as determined by an OAI radiometer for wavelengths between 365 and 43~ nm. The photomask consists of a resolution test pattern where single line and equal line and spaces are repre-sented. The width of these features varies betw2en 1.0 and 3.0 ~m in 0.25 ~m increments. After exposure the wafers are hard baked sequentially on a MTI Inc. hot plate at temperatures ranging from 110C to 150C for up to 60 seconds. A relief ima~e is now observable when the wafers are placed under an optical microscope with monochromatic 520 nm illumination.
After developing the exposed and hard baked wafers in AZ 433 MIF Developer available from the AZ Photoresists Group of American Hoechst Corporation, Somerville, New Jersey (a 0.33N
solution of tetramethylammonium hydroxide) in an immersion mode process for 3 minutes with sli~ht agitation, the wafers are DI
water rinsed and spin dryed. If the wafers are now examined using a scanning electron microscope at 10,000 magnification, 1 ~m single spaces and larger qeometries are clearly seen to be completely opened.

~LZ826~7 The photoresist is made up of a solution containing, 5%
of solids of 4,4'-bis-methoxymethyl diphenyl ether, 6% of solids of 2,3,4 trihydroxy benzophenone 1,2 naphthoquinone-2-diazide-4-sulfonic acid trisester and 89~ of solids of cresol novolac resin in propylene glycol monomethyl ether acetate.
Using this formulation silicon wafers are coated at 4,000 rpm and then soft-baked in a vented convection oven at 90~C
for 30 minutes. Actinic exposure is applied using the Perkin Elmer 220 Micralign aligner through a glass photomask containing a resolution test pattern. Using aperature #4, the scan speeds are varied between 200 and 400 arbitrary energy units. These different scan speeds (each scan speed represents a different - ' :' ' lX~Z6Z~

experiment) corresponds to between 20 and 10 mJ/cm2 respec-tively as determined by an OAI radiometer for wavelengths between 365 and 436 nm. The photomask consists of a resolution test pattern where single line and equal line and spaces are represented. The width of these features varies between 1.0 and 3.0 ~m in 0.25 ~m increments. After exposure the wafers are hard baked sequentially on a MTI Inc. hot plate at temperatures ranging from 11~C to 150C ~or up to 60 seconds. A relief image is now observable when the wafers are placed under an optical microscope with monochromatic 520 nm illumination.
After developing the exposed and hard baked wafers in AZ 433 MIF Developer available from the AZ Photoresists Group of American Hoechst Corporation, Somerville, New ~ersey (a 0.33N
solution of tetramethylammonium hydroxide) in an immersion mode process for 3 minutes with slight agitation, the wafers are DI
water rinsed and spin dryed. If the wafers are now examined using a scanning electron microscope at 10,000 magnification, 1 ~m single spaces and larger geometries are clearly seen to be completely opened.
~0 Example 5 The photoresist is made up of a solution containing, 5%
of solids of 4,4'-bis-methoxymethyl diphenyl ethe~, 6% of solids of 2,3,4 trihydroxy~3'-methyl benzophenone 1,2 naphthoquinone-2-diazide-4-sulfonic acid triester and 89% of solids of cresol novolac resin in propylene glycol monomethyl ether acetate.
Using this formulation silicon wafers are coated at 4,000 rpm and then soft-baked in a vented convection oven at 90C
for 30 minutes. Actinic exposure is applied using the Perkin Elmer 220 Micralign aligner through a glass photomask containing a resolution test pattern. Using aperature ~4, the scan speeds are varied between 200 and 400 arbitrary energy units. These different scan speeds (each scan speed represents a different ~ .

experiment) corresponds to between 20 and 10 mJ/cm2 respec-tively as determined by an OAI radiometer for wavelengths between 365 and 436 nm. The photomask consists of a resolution test pat-tern where single line and equal line and spaces are represented.
The width of these features varies between 1.0 and 3.0 ~m in 0.~5 ~m increments. After exposure the wafers are hard baked sequentially on a MTI Inc. hot plate at temperatures ranging from l10C to 150C for up to 60 seconds. A relief image is now ob~
servable when the wafers are placed under an optical microscope ~ith monochromatic 520 nm illumination.
After developing the exposed and hard baked wafers in AZ 433 MIF Developer available from the AZ Photoresists Group of American Hoechst Corporation, Somerville, ~ew Jersey (a 0.33N
solution of tetramethylammonium hydroxide) in an immersion mode process for 3 minutes with slight agitation, the wafers are DI
water rinsed and spin dryed. If the wafers are now examined us-ing a scanning electron microscope at 10,000 magnification, 1 ~m sinqle spaces and larger geometries are clearly seen to be com-pletely opened.
Example 6 The photoresist is made up of a solution containing, 5 of solids of ~4'-bis-methoxymethyl diphenyl ether, 6% of solids of 2,3,4 trihydroxy-3'-methoxy benzophenone 1,2 naphthoquinone-2- diazide-4-sulfonic acid triester and 89% of solids of cresol novolac resin in propylene glycol monomethyl ether acetate.
Using this formulation silicon wafers are coated at 4,000 rpm and then soft-baked in a vented convection oven at 90C
for 30 minutes. Actinic exposure is applied using the Perkin Elmer 220 Micralign aligner through a glass photomask containing a resolution test pattern. Using aperature #4, the scan speeds are varied between 200 and 400 arbitrary energy units. These di-fferent scan speeds (each scan speed represents a different ' .

~ ~aZ~iz7 experiment) corresponds to between 20 and 10 mJ/cm2 respec-tively as determined by an OAI radiometer for wavelengths between 365 and 436 nm. The photomask consists of a resolution test pattern where single line and equal line and spaces are represented. The width of these features varies between 1.0 and 3.0 ~m in 0.25 ~m increments. After exposure the wafers are hard baked sequentially on a MTI Inc. hot plate at temperatures ranging from 110C to 150C for up to 60 seconds. A relief image is now observable when the wafers are placed under an optical microscope with monochromatic 520 nm illumination.
After developing the exposed and hard baked wafers in AZ 433 MIF Developer available from the AZ Photoresists Group of American Hoechst Corporation, Somerville, New Jersey (a 0.33N
solution of tetramethylammonium hydroxide) in an immersion mode process for 3 minutes with slight agitation, the wafers are DI
water rinsed and spin dryed. If the wafers are now examined using a scanning electron microscope at 10,000 magnification, 1 ~m single spaces and larger geometries are clearly seen to be completely opened.
Example 7 The photoresist is made up of a solution containing, 5%
of solids of 4,4'-bis-methoxymethyl diphenyl ether, 6% of solids of 2,3,4 trihydroxy phenyl pentyl ketone-1,2 naphthoguinone-2-diazide-4-sulfonic acid triester and 89% of solids of cresol novolac resin in propylene glycol monomethyl ether acetate.
Using this formulation silicon wafers are coated at ~,000 rpm and then soft-baked in a vented convection oven at 90C
for 30 minutes. Actinic exposure is applied using the Perkin Elmer 220 Micralign aligner through a glass photomask containing a resolution test pattern. Using aperature #4, the scan speeds are varied between 200 and ~00 arbitrary energy units. These different scan speeds (each scan speed represents a different 8~ 7 experiment) corresponds to between 20 and 10 mJ/cm2 respec-tively as determined by an OAI radiometer for ~ave]engths between 365 and 436 nm. The photomask consists of a resolution test pattern where single line and equal line and spaces are represented. The width of these features varies between 1.0 and 3.0 ~m in 0.25 ~m increments. After exposure the wafers are hard baked sequentially on a MTI Inc. hot plate at temperatures ranging from 110C to 150C for up to 60 seconds. A relief image is now observable when the wafers are placed under an optical microscope with monochromatic 520 nm illumination.
After developing the exposed and hard baked wafers in AZ 433 MIF Developer available from the AZ Photoresists Group of American Hoechst Corporation, Somerville, New Jersey (a 0O33N
solution of tetramethylammonium hydroxide) in an immersion mode process for 3 minutes with slight agitation, the wafers are DI
water rinsed and spin dryed. If the wafers are now examined using a scanning electron microscope at 10,000 magnification, 1 ~m single spaces and larger geometries are clearly seen to be completely opened.
Example 8 The photoresist is made up of a solution containing, 5 of solids of epoxy cresol novolac resin, 6% of solids of 2,3,4 trihydroxy benzophenone 1,2 naphthoquinone-2-diazide-4-sulfonic acid triester and 89~ of solids of cresol novolac resin in propylene glycol monomethyl ether acetate.
Using this formulation silicon wafers are coated at 4,000 rpm and then soft-baked in a vented convection oven at 90C
for 30 minutes. Actinic exposure is applied using the Perkin Elmer 220 Micralign aligner through a glass photomask containing a resolution test pattern. Using aperature #4, the scan speeds are varied between 200 and 400 arbitrary energy units. These different scan speeds (each scan speed represents a different 24 ~

experiment) corresponds to between 20 and 10 mJ/cm2 respectively as determined by an OAI radiometer for wavelengths between 355 and 436 nm. The photomask consists of a resolution test pattern where single line and equal line and spaces are represented. The width of these features varies between 1. e and 3.0 ym i~ 0.25/um increments. After exposure the wafers are hard balced sequentially on a MTI Inc. hot plate at temperatures ranging from 110 C to 150C for up to 60 seconds. A relief image is now observable when the wafers are placed under an optical microscope with monochromatic 520 nm illumination.

After developing the exposed and hard baked wafers in AZ a33 MIF
Developer available from the AZ Photoresists Group of American Hoechst Corporation, Somerville, New Jersey (a 0.33N solution of tetramethylammonium hydroxide) in an immersion mode process for 3 ~inutes with slight agitation, the wafers are DI water rinsed and spin dryed. If the wafers are now examined using a scanning electron microscope at 10,000 magnification, l/um single spaceS
and larger yeometries are .learly seen to be completely opened.

- . ' ''`'''''.

,.

~ ~2~7 Examples 9 - 14 The procedure of example 1 is repeated with the modification that the photoresist is made up of a solution containing ~9 % of solids of cresol novolak resin in propylene glycol monomethyl ether acetate and (~) 5 % of 2,5-bis-(hydroxymethyl)-furan and 6 % of 2,3,4 trihydroxy-3'-methyl-benzophenone-1,2-naphthoquinone-2-diazide-4-sulfonic acid triester, (10) S % of 2,5-bis-(ethoxymethyl)-thiophene and 6 % of 2,3,4-trihydroxy-3'-methyl-benzophenone-1,2-naphthoquinone-2-diazide-4-sulfonic acid triester, (11) 5 % of bis-(3,5-hydroxymethyl-4-hydroxyphenyl)-methane and 6 % of 2,3,4-trihydroxy-3'-methyl-benzop~enone-1,2-naphthoquinone-2-diazide-4-sulfonic acid triester (12) 5 % of 4,4'-bis-acetoxymethyl-diphenylether and 6 % of 2,3,4-trihydroxy-benzophenone-1-2-naphthoquinone- 2-diazide-4-sulfonic acid triester (13) 5 % of l~4-bis(a-hydroxybenzyl)-benzene and 6 % of 2,3,4-trihydroxy-benzophenone-1,2-naphthoquinone- 2-diazide-4-sulfonic acid triester (14) 2,5 % of 2,6-bis-hydroxymethyl-4-methyl-anisole, 2,5 % of 2,2-bis-(3,5-hydroxymethyl-4-hydroxyphenyl)-propane and 6 % of 2,3,4-trihydroxy-benzophenone-1,2-naphthoquinone-2- diazide-4-sulfonic acid triester.
The results are similar to those in the preceding examples.

. _, ~

.

Claims

1. A process for preparing a negative image of a posi-tive working photographic element which comprises in order:
a) forming a composition which comprises i) from about 1% to about 25% based on the weight of solid parts of the composition of a photo sensitive compound having the formula wherein R1 = 1,2 benzoquinone-2-diazide-4-sulfonyl;
1,2 naphthoquinone-2-diazide-4-sulfonyl;
or 1,2 anthraquinone-2-diazide-4-sulfonyl R2 is H, R5, OR6 or ? - R7 R3 is H, R5, OR6 or ? - R7 R4 is H, R5, OR6 or ? - R7 R6 is H, alkyl, aryl, aralkyl or R1 R5,R7 are alkyl, aryl or aralkyl ii) from about 75% to about 99% based on the weight of the solid parts of the composition of a novo-lak, or polyvinyl phenol; and iii) from about 0.5% to about 20% based on the weight of the solid parts of the composition of a cross-linking compound which, when in the presence of that amount and strength of the acid generated when said diazide is exposed to actinic radiation, is capable of cross-linking said resin - 27a -under the application of the heating condi-tions of step (e); and iv) sufficient solvent to dissolve the foregoing composition components; and b) coating said composition on a suitable substrate;
and c) heating said coated substrate at a temperature of from about 2°C to about 1°C until substantially all of said solvent is dried off; and d) imagewise exposing said composition to actinic radiation; and e) heating said coated substrate at a temperature of at least about 95°C to about 16°C for from about 1 seconds or more to crosslink said resin; and f) removing the unexposed non-image areas of said com-position with a suitable developer.

2. A process according to claim 1 wherein component (ii) of step a) is polyparavinyl phenol resin.

3. The process of claim 1 or 2 wherein said photosensit-izer is 2,3,4 trihydroxybenzophenone-1,2 naphthoquinone-2-diazide-4-sulfonic acid trisester.

4. The process of claim 1 or 2 wherein said crosslinker is a compound having the formula (R1O-CHR3)n-A-(CHR3-OR2)m wherein A is B or B-Y-B and B is a substituted or unsubstituted mononuclear or fused polynuclear aromatic hydrocarbon or an oxygen- or sulfur- containing heterocyclic aromatic compound, Y is a single bond, C1 to C4-alkylene or -alkylene dioxy, which chain can be interrupted by -O-, -S-, -SO2-, -CO-, -CO2-, -O-CO2-, -CONH-, or phenylene dioxy, R1 and R2 are the same or different and represent hydrogen, C1 to C6-alkyl, -cycloalkyl, substituted or unsubstituted aryl, aralkyl or acyl, R3 is hydrogen, C1 to C4-alkyl or substituted or unsubstituted phenyl, n means 1 to 3 and m means 0 to 3, under the provision that n + m is at least 2.

5. The process of claim 1 or 2 wherein said cross-linker is a compound or a mixture of compounds selected from the group of dimethyl paracresol, 4,4'-bis-methoxymethyl diphenyl ether, epoxy cresol novolak resin, 2,5-bis-(hydroxymethyl)-furan, 2,5-bis-(ethoxymethyl)-thiophene, bis-(3,5 hydroxymethyl-4-hydroxyphenyl)-methane, 4,4'-bis-acetoxy-methyl-diphenylether, 1,4-bis-(.alpha.-hydroxybenzyl)-benzene, 2,6-bis-hydroxymethyl-4-methyl-anisole and 2,2-bis-(3,5-hydroxymethyl-4-hydroxyphenyl)-propane.

6. The process of claim 1 wherein said cross-linker is dimethylol paracresol.

7. The process of claim 1 wherein said cross-linker is 4,4'-bis-methoxymethyl diphenyl ether.

8. The process of claim 1 wherein said cross-linker is an expoxy cresol novolaX resin.

9. The process of claim 1 wherein said solvent comprises propylene glycol alkyl ether acetate.

10. The process of claim 1 wherein said substrate is selected from the group consisting of silicon, aluminum or polymeric resins, silicon dioxide, doped silicon dioxide, sili-con nitride, tantalum, copper, polysilicon, ceramics and alum-inum/copper mixtures.

11. The process of claim 1 wherein said composition fur-ther comprises one or more compounds selected from the group consisting of colorants, dyes, anti-striation agents, leveling agents, plasticizers, adhesion promoters, speed enhancers, and surfactants.

12. The process of claim 1 wherein said step (e) is con-ducted at a temperature of from about 95°C to about 150°C.

13. The process of claim 1 wherein said step (e) is con-ducted at a temperature of from about 112°C to about 120°C.

14. The process of claim 1 wherein said step (e) is con-ducted for from about 10 seconds to about 90 seconds.

15. The process of claim 12 wherein said step (e) is con-ducted for from about 10 seconds to about 90 seconds.

16. The process of claim 13 wherein said step (e) is con-ducted for from about 10 seconds to about 90 seconds.

17. The process of claim 1 wherein said developer is an aqueous alkaline solution.

18. The process of claim 17 wherein said developer com-prises sodium hydroxide and/or tetramethyl ammonium hydroxide.

19. The process of claim 1 wherein said resin is a novolak, said cross linker comprises dimethylol paracresol, said heating step (e) is conducted at a temperature of from about 112°C to about 120°C for up to 90 seconds, and said developer comprises an aqueous solution of sodium hydroxide and/or tetramethyl ammonium hydroxide.

20. The photographic element prepared according to the process of claim 1.

21. The photographic element prepared according to the process of claim 15.

22. The photographic element prepared according to the process of claim 19.