WO1997000465A1

WO1997000465A1 - Resin compositions for photoresist applications

Info

Publication number: WO1997000465A1
Application number: PCT/US1996/008179
Authority: WO
Inventors: James R. Sounik; Stanley A. Ficner; Ralph R. Dammel; Ping-Hung Lu; Thomas J. Lynch; Dana L. Durham
Original assignee: Clariant International Ltd.
Priority date: 1995-06-16
Filing date: 1996-05-31
Publication date: 1997-01-03

Abstract

The invention relates to the use of thermally stable, water-insoluble and alkali-soluble polyalkylated phenolic resins in photosensitive compositions, where the polyalkylated resin is a reaction product of a carboxylic acid and at least one substituted phenyl carbinol. The invention also relates to the use of these photosensitive compositions in manufacturing semiconductor devices.

Description

DESCRIPTION RESIN COMPOSITIONS FOR PHOTORESIST APPLICATIONS

BACKGROUND OF THE INVENTION The present invention relates to thermally stable, alkali-soluble polyalkylated phenolic resins and their use in light-sensitive compositions. The present invention also relates to light-sensitive compositions useful in positive- working photoresist compositions. Further, the present invention relates to substrates coated with these light-sensitive compositions as well as the process of coating, imaging and developing these light-sensitive mixtures on these substrates.

Photoresist compositions are used in microlithography processes for making miniaturized electronic components such as in the fabrication of computer chips and integrated circuits. Generally, in these processes, a thin coating of film of a photoresist composition is first applied to a substrate material, such as silicon wafers used for making integrated circuits. The coated substrate is then baked to evaporate any solvent in the photoresist composition and to fix the coating onto the substrate. The baked coated surface of the substrate is next subjected to an image-wise exposure to radiation.

This radiation exposure causes a chemical transformation in the exposed areas of the coated surface. Visible light, ultraviolet (UV) light, electron beam and X-ray radiant energy are radiation types commonly used today in microlithographic processes. After this image-wise exposure, the coated substrate is treated with a developer solution to dissolve and remove either the radiation-exposed or the unexposed areas of the coated surface of the substrate.

There are two types of photoresist compositions, negative-working and positive-working. When negative-working photoresist compositions are exposed image-wise to radiation, the areas of the resist composition exposed to the radiation become less soluble to a developer solution (e.g. a cross- linking reaction occurs) while the unexposed areas of the photoresist coating remain relatively soluble to such a solution. Thus, treatment of an exposed negative-working resist with a developer causes removal of the non-exposed areas of the photoresist coating and the creation of a negative image in the coating, thereby uncovering a desired portion of the underlying substrate surface on which the photoresist composition was deposited.

On the other hand, when positive-working photoresist compositions are exposed image-wise to radiation, those areas of the photoresist composition exposed to the radiation become more soluble to the developer solution (e.g. a rearrangement reaction occurs) while those areas not exposed remain relatively insoluble to the developer solution. Thus, treatment of an exposed positive-working photoresist with the developer causes removal of the exposed areas of the coating and the creation of a positive image in the photoresist coating. Again, a desired portion of the underlying substrate surface is uncovered.

After this development operation, the now partially unprotected substrate may be treated with a substrate-etchant solution or plasma gases and the like. The etchant solution or plasma gases etch that portion of the substrate where the photoresist coating was removed during development. The areas of the substrate where the photoresist coating still remains are protected and, thus, an etched pattem is created in the substrate material which corresponds to the photomask used for the image-wise exposure of the radiation. Later, the remaining areas of the photoresist coating may be removed during a stripping operation, leaving a clean etched substrate surface. In some instances, it is desirable to heat treat the remaining photoresist layer, after the development step and before the etching step, to increase its adhesion to the underlying substrate and its resistance to etching solutions.

Positive working photoresist compositions are currently favored over negative working resists because the former generally have better resolution capabilities and pattern transfer characteristics. Photoresist resolution is defined as the smallest feature which the resist composition can transfer from the photomask to the substrate with a high degree of image edge acuity after exposure and development. In many manufacturing applications today, resist resolution on the order of one micron or less are necessary. In addition, it is almost always desirable that the developed photoresist wall profiles be near vertical relative to the substrate. Such demarcations between developed and undeveloped areas of the resist coating translate into accurate pattem transfer of the mask image onto the substrate.

SUMMARY OF THE INVENTION The present invention relates to a resist composition comprising homopolymers or copolymers synthesized from a mixture of carboxylic acid and at least one substituted phenyl carbinol whose structure is

(I) wherein: (a) Ri is selected from the group consisting of H, C-* -C₂o -alkyl, substituted and unsubstituted phenyl and C(O)R₈ (where R₈ is Ci -C₂o alkyl); (b)

R₂ is selected from the group consisting of H and C-i -C₂o alkyl; and (c) R₃-R₇are each independently selected from the group consisting of H, Ci -C₂₀ alkyl, OR₉ (where R₉ is H, Ci -C₂o alkyl, esters thereof, or substituted or unsubstituted phenyl), halogen, benzotriazole, nitro, or amino, with the proviso that at least one of R₃-R₇ is OR₉, in the presence of a suitable catalyst for a sufficient period of time and under suitable conditions of temperature and pressure to form said polyalkylated polymer, and a photosensitizer. This invention further relates to the use of such photoresists in producing semiconductor devices.

The polyalkylated phenolic resin utilized in the present invention comprises a water insoluble, aqueous alkali soluble resin obtained by: (a) reacting at least one substituted phenyl carbinol with a carboxylic acid for a sufficient period of time and under suitable conditions of temperature and pressure to form a reaction mixture,

(b) polymerizing said reaction mixture in the presence of a catalyst for a sufficient period of time and under suitable conditions of temperature and pressure to form a polyalkylated phenol.

The invention provides a positive photoresist composition comprising an admixture of:

A) a photosensitive component in an amount sufficient to uniformly photosensitize the photoresist composition; and

B) a water insoluble, aqueous alkali soluble polyalkylated phenolic resin obtained by polymerizing a mixture of carboxylic acid and at least one substituted phenyl carbinol whose structure is

(I) wherein: (a) Ri is selected from the group consisting of H, Ci -C₂o -alkyl, substituted and unsubstituted phenyl and C(O)R₈ (where R₈ is Ci - C₂o alkyl); (b) R₂ is selected from the group consisting of H and Ci -C20 alkyl; and (c) R₃-R7are each independently selected from the group consisting of H, Ci -C₂₀ alkyl, OR₉ (where R₉ is H, Ci -C₂₀ alkyl, esters thereof, or substituted or unsubstituted phenyl), halogen, benzotriazole, nitro, or amino, with the proviso that at least one of R3-R7 is OR₉, in the presence of a suitable catalyst for a sufficient period of time and under suitable conditions of temperature and pressure to form said polyalkylated resin, the polyalkylated resin being present in the photoresist composition in an amount sufficient to form a substantially uniform photoresist composition; and C) a suitable solvent.

The invention further provides a method for producing a semiconductor device by producing a photoresist image on a substrate by coating a suitable substrate with a positive working photoresist composition which comprises an admixture of:

A) a photosensitive component in an amount sufficient to photosensitize the photoresist composition; and B) a water insoluble, aqueous alkali soluble polyalkylated resin obtained by polymerizing a mixture of a carboxylic acid and at least one substituted phenyl carbinol whose structure is

(I) wherein: (a) R_T is selected from the group consisting of H, Ci -C₂o -alkyl, substituted and unsubstituted phenyl and C(O)R₈ (where R₈ is Ci -

C₂o alkyl); (b) R₂ is selected from the group consisting of H and Ci -C₂0 alkyl; and (c) R₃-R₇are each independently selected from the group consisting of H, Ci -C₂o alkyl, OR₉ (where R₉ is H, Ci -C₂₀ alkyl, esters thereof, or substituted or unsubstituted phenyl), halogen, benzotriazole, nitro, or amino, with the proviso that at least one of R3-R7 is OR₉, in the presence of a suitable catalyst for a sufficient period of time and under suitable conditions of temperature and pressure to form said polyalkylated resin, the polyalkylated resin being present in the photoresist composition in an amount sufficient to form a substantially uniform photoresist composition; C) a suitable solvent; and

D) heat treating the coated substrate until substantially all of the solvent is removed; image-wise exposing the photosensitive composition; and removing the image-wise exposed areas of such composition with an aqueous alkaline developer. Optionally one may perform a baking of the substrate either immediately before or after the removing step. The polyalkylated polymer may additionally be used as a resin in a negative working resist, image reversal resist, deep uv resist or in a multilayer resist system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the production of the relief image of the present invention, one coats and dries the foregoing photoresist composition on a suitable substrate. Novolak resins have been commonly used in the art of photoresist manufacture as exemplified by "Chemistry and Application of Phenolic Resins",

Knop A. And Scheib, W.; Springer Verlag, New York, 1979 in Chapter 4. Similarly, o-quinone diazides are well known to the skilled artisan as demonstrated by "Light Sensitive Systems", Kosar, J.; John Wiley & Sons, New York, 1965 Chapter 7.4. However, the instant invention has found that the use of particular polyalkylated resins, as opposed to those taught in the prior art, produces a photoresist having high thermal stability, and good resolution.

The particular polylalkylated resins employed by this invention are water insoluble, aqueous alkali soluble resins with high Tg and are obtained by a process which comprises polymerizing a mixture of carboxylic acid and at least one substituted phenyl carbinol whose structure is

(I) wherein: (a) R is selected from the group consisting of H, Ci -C₂0 -alkyl, substituted and unsubstituted phenyl and C(O)Rβ (where R₈ is Ci -C₂0 alkyl); (b) R₂ is selected from the group consisting of H and Ci -C₂o alkyl; and (c) R₃-R₇are each independently selected from the group consisting of H, Ci -C₂o alkyl, OR₉

(where R₉ is H, Ci -C₂o alkyl, esters thereof, or substituted or unsubstituted phenyl), halogen, benzotriazole,nitro, or amino, with the proviso that at least one of R3-R7 is OR₉, in the presence of a suitable catalyst for a sufficient period of time and under suitable conditions of temperature and pressure to form said polyalkylated resin.

Substituted phenyl as used herein means phenyl substituted by at least one substituent selected from the group consisting of halogen (chlorine, bromine, fluorine, or iodine), amino, nitro, hydroxy, alkyl, alkoxy which means straight or branched chain alkoxy having 1 to 10 carbon atoms and includes, for example, methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, secondary butoxy, tertiary butoxy, pentyloxy, isopentyloxy, hexyloxy, heptryloxy, octyloxy, nonyloxy, and decyloxy, haloalkyl which means straight or branched chain alkyl having 1 to 8 carbon atoms which is substituted by at least one halogen, and includes, for example, chloromethyl, bromomethyl, fluoromethyl, iodomethyl, 2-chloroethyl, 2-bromoethyl, 2-f luoroethyl, 3- chloropropyl, 3-bromopropyl, 3-fluoropropyl, 4-chlorobutyl, 4-fluorobutyl dichloromethyl, dibromomethyl, difluoromethyl, diiodomethyl, 2,2-dichloroethyl, 2,2-dibromoethyl, 2,2-difluoroethyl, 3-3-dichloropropyl, 3,3-difluoropropyl, 4,4- dichlorobutyl, 4,4-difluorobutyl, trichloromethyl, 4,4-difluorobutyl, trichloromethyl, trifluoromethyl, 2,2,2-trifluoroethyl, 2,3,3-trifluoropropyl, 1,1 ,2,2- tetraf luoroethyl, and 2,2,3,3-tetrafluoropropyl.

In the above definitions and throughout the present specification, alkyl means straight or branched chain alkyl having 1 to 20 carbon atoms, and includes, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, secondary butyl, tertiary butyl, pentyl, isopentyl, neopentyl, hexyl, heptyl, octyl, 2-ethylexyl, 1,1,3,3-tetramethylbutyl, nonyl, decyl, dodecyol, tetradecyl, nexadecyl, octadecyl, and eicosyl.

The polyalkylated resin as used in this invention may also include moieties derived from a polymer, copolymer, block or graft polymer having at least some hydroxy groups in the structure. It may be understood that there may also be present in the polyalkylated resin, moieties derived from monomers which do not contain a hydroxy group; these include, without limitation,

(a) substituted phenols

where x= 0-6 and y=0-6 and R₃ is the same as defined herein,

(b) substituted triaryalkyls

where n=0-2 and R₂ and R₃ are the same as defined herein.

It has unexpectedly been found that the use of carboxylic acid with a carbinol to form a reaction mixture and the subsequent polymerization thereof results in a new polyalkylated resin especially useful in photosensitive compositions. The carboxylic acid employed not only acts as a reactant, but also as a solvent.

The carboxylic acid employed includes, without limitation, formic, acetic, propanoic, butyric, valeric, caproic, heptanoic, octanoic, nonanoic, undecanoic, isobutyric, isovaleric, cyclohexane carboxylic acid, and mixtures thereof. It is a;so critical that the particular carboxylic acid be a saturated carboxylic acid, and/or ring carbocyclic carboxylic acid. The amount of carboxylic acid used is any amount which provides a molar reaction and also acts as a solvent.

The catalyst employed in the process is selected from the group H₂SO₄, HCI, Aids, H₃PO , oxalic acid, SnCI₂, BF_3l BBr_3l BCI₃, para-toluene sulfonic acid, and methane sulfonic acid. Thus, Lewis acids are suitable.

The catalyst is used in any amount in order to facilitate the reaction, i.e. polymerization, to yield the subject polyalkylated resin. Such amounts generally are from about one part per million (ppm) to about 100,000 ppm, or higher. The temperature employed in the polymerization is generally less than about 120°C, more specifically from about 0°C to about 120°C. The reaction pressure may be subatmospheric, atmospheric, or superatmospheric.

The length of time which this polymerization step is conducted is not critical and the only requirement is that the polymerization be conducted for a period of time sufficient to form a polyalkylated resin. Generally, this period is at least five minutes and may be as long as 25 hours.

After the polymerization of the reaction mixture (i.e. carboxylic acid + carbinol + any nucleating agent), the desired end product is recovered from the reaction product and the residual fraction containing any unreacted carbinol can be recycled as part of the starting material for the next cycle. The end product may be recovered from the reaction product by any method; for example, it can be separated from the fraction containing the unreacted carbinol by filtration or any other suitable technique.

One can employ a nucleating agent like a seed monomer in order to prepare the reaction mixture. Such material does not have to be a carbinol falling within Formula I, nor does it have to contain any hydroxy groups. Such nucleating agents may include, without limitation, the substituted phenols and substituted triarylalkyls defined herein.

One can also employ a chain terminating agent after the polymerization step. Any type of chain terminating agent may be used as long as there is no substantial adverse effect on the polyalkylated resin. One can also employ two or more carbinols in the reaction mixture or to use one or more carbinols in subsequent polymerizations after the initial polymerization; i.e. sequential polymerization with a different carbinol at each polymerization stage. One can also employ a polyhydroxystyrene homopolymer to add to the

"carbinol/carboxylic acid" reaction mixture and then subject the overall reaction mixuture to alkylation/polymerization to prepare a partial novolak type structure of polyhydroxystyrene.

The resulting polyalkylated resin has a molecular weight in the range of from about 1 ,000 to about 500,000, preferably from about 1 ,000 to about

100,000 and more preferably from about 1 ,000 to about 30,000.

The said polyalkylated resin may additionally be treated to improve the properties of the polyalkylated resin. Treatments such as fractionation, ion- exchange and/or aqueous acid extraction to remove impurities, blending of the polyalkyated resin with like resin or with other alkali-soluble resins using parameters of dissolution rate of the resin in an alkaline solution, and/or molecular weight. Preferable levels for metal ions, typically sodium and iron ions, are below 100 ppb each, more preferably below 50 ppb each and most preferably below 10 ppb each. The said polyalkylated resin may also be treated chemically, e.g partially or fully blocking the hydroxyl group of said resin with groups that can be deblocked in the presence of an acid, e.g. tertiary butyl carbonate.

Among the photosensitive components that may be utilized to produce photoresist compositions are the 2,1,4-, 2,1,5- and 2,1,6- diazonaphthoquinone sulfonic acid esters of substituted tris hydroxyphenylalkanes or the tri-, tetra-, hexa- hyroxybenzophenones well known to those skilled in the art, such as described in U.S. Patents 3,106,465 and 4,719,167, which are incorporated herein by reference. Other photoacid generators included herein but not limited to are onium salts, triazines, and diazos sensitive to deep uv radiation. The photoresist composition is formed by blending the ingredients in a suitable solvent. In the preferred embodiment, the amount of polyalkylated resin in the photoresist preferably ranges from 5% to about 95% and more preferably from about 15% to about 85% based on the weight of the solid; i.e., non-solvent photoresist components. In the preferred embodiment, the photosensitizer is present in the photoresist in an amount of from about 5% to about 50% preferably from about 10% to about 35% based on the weight of the solid photoresist components. In producing the photoresist composition, the polyalkylated resin and sensitizer are mixed with such solvents as propylene glycol mono-alkyl ether, propylene glycol alkyl ether acetate, butyl acetate, xylene, ethylene glycol monoethyl ether acetate, propylene glycol mono-methyl ether acetate, ethyl lactate, ethyl-3-ethoxypropionate, and mixtures of ethyl lactate and ethyl-3-ethoxyρropionate, among others.

Other optional ingredients 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 of polyalkylated resin, sensitizer 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 (Cl. No. 42535), Crystal Violet (Cl. 42555). Malachite Green (Cl. No. 42000), Victoria Blue B (Cl. No. 44045) and Neutral Red (Cl. No. 50040) at one to ten percent weight levels, based on the combined weight of novolak and sensitizer.

The dye additives can help provide increased resolution by inhibiting back scattering of light off the substrate, can also provide good visual recognition or aid in alignment.

Anti-striation agents, such as fluorinated surfactants amongst others, may be used at up to about a five percent weight level, based on the combined weight of resin and sensitizer. Plasticizers which may be used include, for example, phosphoric acid tri-(beta-chloroethyl)-ester; stearic acid; dicamphor; polypropylene; acetal resins; phenoxy resins; and alkyl resins, at about one to ten percent weight levels, based on the combined weight of novolak and sensitizer. The plasticizer additives improve the coating properties of the material and enable the application of a film that is smooth and of uniform thickness to the substrate.

Adhesion promoters which may be used include, for example, beta-(3,4- epoxy-cyclohexyl)-ethyltrimethoxysilane; p-methyl-disilane-methyl methacrylate; vinyltrichlorosilane; and gamma-amino-propyl triethoxysilane up to about a 4 percent weight level, based on the combined weight of resin and sensitizer. Development speed enhancers that may be used include, for example, picric acid, nicotinic acid, aromatic sulfonic acid, nitrocinnamic acid, or polyhydroxy phenols up to about a 20 percent weight level, based on the combined weight of novolak and sensitizer.

The polyalkylated resin when mixed with a photosensitive photogenerator such as 2,1 ,4- diazonaphthoquinone sulfonate, crosslinking agent such as dimethylolparacresol or melamines and a suitable solvent can provide a photosensitive composition that can be image reversed as is described in US 4,931 ,381 , which is incorporated herein by reference.

Dissolution inhibitors, such as ketals and acetals, can be added to the polyalkylated resin and a photoacid generator to form compositions that are photosensitive to ultra violet light (440nm-190nm).

A planarization layer composed of the polyalkylated resin of this invention can be used as a bottom layer for a photosensitive composition. Top coats, antireflective coatings, contrast enhancement layers are examples of multilayer systems that can be used in conjunction with the novel photosensitive composition described herein.

The coating solvents may be present in the overall composition in an amount of up to 95% by weight of the solids in the composition. Solvents, of course are substantially removed after coating of the photoresist solution on a substrate and drying. Non-ionic surfactants that may be used include, for example, nonylphenoxy poly(ethyleneoxy) ethanol; octylphenoxy ethanol at up to about 10% weight levels, based on the combined weight of resin and sensitizer. The prepared photoresist solution, can be applied to a substrate 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 with respect to the percentage of solids content, in order to provide coating of the desired thickness, given the type of spinning equipment utilized and the amount of time allowed for the spinning process. Suitable substrates include silicon, aluminum, polymeric resins, silicon dioxide, doped silicon dioxide, silicon nitride, tantalum, copper, polysilicon, ceramics, aluminum/copper mixtures; gallium arsenide and other such Group IIIA compounds.

The photoresist coatings produced by the described procedure are particularly suitable for application to thermally grown silicon/silicon dioxide- coated wafers, such as are utilized in the production of microprocessors and other miniaturized integrated circuit components. An aluminum/aluminum oxide wafer can also be used. The substrate may also comprise various polymeric resins, especially transparent polymers such as polyesters. The substrate may have an adhesion promoted layer of a suitable composition, such as one containing hexa-alkyl disilazane.

The photoresist composition solution is then coated onto the substrate, and the substrate is treated at a temperature from about 70°C to about 110°C for from about 30 seconds to about 180 seconds on a hot plate or for from about 15 to about 90 minutes in a convection oven. This temperature treatment is selected in order to reduce the concentration of residual solvents in the photoresist, while not causing substantial thermal degradation of the photosensitizer. In general, one desires to minimize the concentration of solvents and this first temperature treatment is conducted until substantially all of the solvents have evaporated and a thin coating of photoresist composition, on the order of one micron in thickness, remains on the substrate. In a preferred embodiment the temperature is from about 85°C to about 95°C The treatment is conducted until the rate of change of solvent removal becomes relatively insignificant. The temperature and time selection depends on the photoresist properties desired by the user, as well as the equipment used and commercially desired coating times. The coating substrate can then be exposed to actinic radiation, e.g., ultraviolet radiation, at a wavelength of from about 300 nm to about 450 nm, x-ray, electron beam, ion beam or laser radiation, in any desired pattern, produced by use of suitable masks, negatives, stencils, templates, etc.

The photoresist is then optionally subjected to a post exposure second baking or heat treatment either before or after development. The heating temperatures may range from about 90°C to about 120°C, more preferably from about 100°C to about 110°C The heating may be conducted for from about 30 seconds to about 2 minutes, more preferably from about 60 seconds to about 90 seconds on a hot plate or about 30 to about 45 minutes by convection oven. The exposed photoresist-coated substrates are developed to remove the image-wise exposed areas by immersion in an alkaline developing solution or developed by spray development process. 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 photoresist coating has dissolved from the exposed areas. Developers may include aqueous solutions of ammonium or alkali metal hydroxides, choline or ethanolamine. One preferred hydroxide is tetramethyl ammonium hydroxide. After removal of the coated wafers from the developing solution, one may conduct an optional post- development heat treatment or bake to increase the coating's adhesion and chemical 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 industrial applications, particularly in the manufacture of microcircuitry units on silicon/silicon dioxide- type substrates, the developed substrates may be treated with a buffered, hydrofluoric acid base etching solution. The photoresist compositions of the present invention are resistant to acid-base etching solutions and provide effective protection for the unexposed photoresist-coating areas of the substrate. The following specific examples will provide detailed illustrations ofthe methods of producing and utilizing compositions 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, parameters or values which must be utilized exclusively in order to practice the present invention.

Example 1-11 The following procedure was used in Examples 1-11 to prepare the polyalkylated resin. This procedure illustrates Example 4.

A three-neck three-liter flask was fitted with a condenser, thermowell, nitrogen purge, and mechanical stirrer. To the flask was added 4- hydroxyphenymethylcarbinol (HPMC) (352.0g 2.55 mol) and glacial acetic acid (1051.9g, 17.52 mol). Not all of the HPMC was dissolved. The suspension was cooled to 9°C using an ice bath and sulfuric acid (1.0 g) was added. The ice bath was removed and the suspension was allowed to warm, and at 19°C, all of the HPMC dissolved. The mixture exothermed, reaching a maximum temperature of 35°C The color of the solution changed from colorless to a faint blue during the exotherm. The reaction mixture was stirred overnight at room temperature and the color changed to a faint golden color. The solution was poured into water (3x 30 ml.), and the solid was isolated by filtration. The solid was washed with water (3x 1000 ml.), vacuum dried (50°C, 60° torr, 2 days), and weighed (288.7 g, 94.3%).

The solid obtained was a bright white powder which was soluble in acetone, methanol, tetrahydrofuran, and aqueous base and insoluble in non¬ polar organics. The GPC weight average molecular weight was 5600 and the number average molecular weight was 3675, giving a polydispersity of 1.53. The thermal stability by TGA showed no decomposition below 200°C and the glass transition temperature was 143°C The experimental conditions and results are shown in Tables 1 , 2, 3, and 4 for Examples 1-11. Example 12 Photoresist solution was prepared as follows: A total of 9.75g of the polyalkylated polymer of Example 4 was added to 37.37g of a mixture of 85 parts ethyl lactate and 15 parts n-butyl acetate. A photosensitizer [2.75g of 2, 1, 5- (60%) and 2, 1, 4- (40%) diazonaphthoquinone sulfonic acid ester (97% esterified) of trihydroxyphenylethane] was added. 0.013g of surfactant [FC- 430^* available from 3M] was then added. The photoresist solution was spin coated, using standard techniques, onto a silicon wafer at a constant speed, to obtain a layer of photoresist having an initial thickness of 1.07μm. The film was soft baked on a hot plate at 110°C for 60 seconds. The film was exposed by a

0.54 NIKON^* i-line stepper and baked at 110°C for 60 seconds. It was developed for 52 seconds at 21.6°C, using an AZ^*300 MIF TMAH (tetramethyl ammonium hydroxide) developer puddle. Small line/space features were clearly resolved on the silicon wafer.

Example 13 Photoresist solution was prepared as follows: A total of 10.00g of the polyalkylated polymer of Example 4 was added to 37.37g of a mixture of photosensitizers [2.50g of 2, 1 , 5- (60%) and 2, 1 , 4- (40%) diazonaphthoquinone sulfonic acid ester (97% esterified) of trihydroxyphenylethane] was added. 0.013g of surfactant [FC-430 fluoroaliphatic polymeric ester (98.5%), toluene (1.5%) available from 3MJ was then added. The photoresist solution was spin coated, using standard techniques, onto a silicon wafer at a constant speed, to obtain a layer of photoresist having an initial thickness of 1.07μm. The film was soft baked on a hot plate at 110°C for 60 seconds. The film was exposed by a 0.54 NIKON^* i- line stepper and baked at 110°C for 60 seconds. It was developed for 52 seconds at 21.6°C, using an AZ^*300 MIF TMAH developer puddle. Small line/space features were clearly resolved on the silicon wafer. Example 14 Photoresist solution was prepared as follows: A total of 10.25g of the polyalkylated polymer of Example 4 was added to 37.37g of a mixture of photosensitizers [2.25g of 2, 1, 5- (60%) and 2, 1, 4- (40%) diazonaphthoquinone sulfonic acid ester (97% esterified) of trihydroxyphenylethane] was added. 0.013g of FC-430^* surfactant (available from 3M) was then added. The photoresist solution was spin coated, using standard techniques, onto a silicon wafer at a constant speed, to obtain a layer of photoresist having an initial thickness of 1.07μm. The film was soft baked on a hot plate at 110°C for 60 seconds. The film was exposed by a 0.54 NIKON i- line stepper and baked at 110°C for 60 seconds. It was developed for 52 seconds at 21.6°C, using an AZ^*300 MIF TMAH developer puddle. Small line/space features were clearly resolved on the silicon wafer.

Example 15

Photoresist solution was prepared as follows: A total of 9.75g of the polyalkylated polymer of Example 4 was added to 37.37g of a mixture of photosensitizers [2.75g of 2, 1 , 5- (60%) and 2, 1 , 4- (60%) diazonaphthoquinone sulfonic acid ester (95%) of trihydroxyphenylethane] was added. 0.013g of FC-430^* surfactant (available from 3M) was then added. The photoresist solution was spin coated, using standard techniques, onto a silicon wafer at a constant speed, to obtain a layer of photoresist having an initial thickness of 1.07μm. The film was soft baked on a hot plate at 110°C for 60 seconds. The film was exposed by a 0.42 GCA^* g-line stepper and baked at 110°C for 60 seconds. It was developed for 52 seconds at 21.6°C, using an

AZ^*300 MIF TMAH developer puddle. Small line/space features were clearly resolved on the silicon wafer.

Example 16 Photoresist solution was prepared as follows: A total of 10.00g of the polyalkylated polymer of Example 4 was added to 37.37g of a mixture of photosensitizers [2.50g of 2, 1, 5- (60%) and 2, 1, 4- (40%) diazonaphthoquinone sulfonic acid ester (95% esterified) of trihydroxyphenylethane] was added. 0.013g of FC-430^* surfactant (available from 3M) was then added. The photoresist solution was spin coated, using standard techniques, onto a silicon wafer at a constant speed, to obtain a layer of photoresist having an initial thickness of 1.07μm. The film was soft baked on a hot plate at 110°C for 60 seconds. The film was exposed by a 0.42 GCA^* g- line stepper and baked at 110°C for 60 seconds. It was developed for 52 seconds at 21.6°C, using an AZ^*300 MIF TMAH developer puddle. Small line/space features were clearly resolved on the silicon wafer.

Example 17 Photoresist solution was prepared as follows: A total of 10.25g of the polyalkylated polymer of Example 4 was added to 37.37g of a mixture of photosensitizers [2.25g of 2, 1 , 5- (60%) and 2, 1 , 4- (40%) diazonaphthoquinone sulfonic acid ester (97% esterified) of trihydroxyphenylethane] was added. 0.013g of FC-430^* surfactant (available from 3M) was then added. The photoresist solution was spin coated, using standard techniques, onto a silicon wafer at a constant speed, to obtain a layer of photoresist having an initial thickness of 1.07μm. The film was soft baked on a hot plate at 110°C for 60 seconds. The film was exposed by a 0.42 GCA'g- line stepper and baked at 110°C for 60 seconds. It was developed for 52 seconds at 21.6°C, using an AZ^*300 MIF TMAH developer puddle. Small line/space features were clearly resolved on the silicon wafer.

Example 18 The polyalkylated copolymer from Example 4 (20.0 g) was dissolved in acetone (110 ml.) in a 500 ml. jacketed flask. The flask was fitted with a mechanical stirrer, condenser, and thermometer, and the jacket temperature were set to 30°C The mixture was stirred for an hour. A solution of ditertbutyl dicarbonate (6.70 g) in acetone (10.7ml.) was added. Then, a solution in dimethylaminopyridine (0.026 g) in acetone (3 mL) was added slowly over 20 min, after which the stirring was continued for 24 hours. The reaction solution was slowly added to a mixture of 1.2 L. water and 12 ml, of isopropyl alcohol which yielded a white flocculant precipitate. The precipitate was collected by filtration and partially dried by continuing to pass air through the filter funnel for

2 hr. The product was transferred to a vacuum chamber and dried at 25 in. Hg vacuum, at room temperature for 12 hours. Isolated yield: 19.1 g

Example 19 A photoresist solution was made by mixing the following components:

0.968g of photoactive compound (2, 1, 4- (95%) and 2, 1,5- (5%) diazonaphthoquinone sulfonic acid ester of trihydroxybenzophenone), 3.432g the resin from Example 18, 15.55g of propylene glycolmonomethylether acetate (PGMEA), and 0.052g 10% antistration agent in PGMEA. The solution was filtered through a 0.1 μm filter.

Three milliliters of this photoresist was pipetted onto a 4 inch silicon wafer that had been primed with HMDS (hexamethyl disilazane). After spinning at 2400 RPM and softbaking at 90°C for 60 seconds, a 0.93μm film was formed on the silicon wafer. The wafer was covered with a chromed gradient mask of quartz glass from Dupont Tau. After exposing using the energy of a DUV lamp contact expose unit (made by Hybrid Technology Group, San Jose, CA), of 1.8mW/cm² (mW=milliwatts) for 83.3 sec (150 mJ/cm²⁾), the coated wafer was placed on a vacuum hotplate and postexposure baked at 120°C for 60 seconds. After cooling for 3 minutes, the coated wafer was immersion developed using AZ^® 300 MIF TMAH developer for 60 seconds at 21.6°C The

Dose to Clear was determined to be 43 mJ/cm² from the energy of the area where total film loss was seen. Small line/space features were resolved.

Claims

Claims:

1. A photoresist composition comprising:

A) a photosensitive component in an amount sufficient to photosensitize the photoresist composition;

B) a film-forming polyalkylated polymer prepared by a process comprising the steps of i) reacting at least one substituted phenyl carbinol with a carboxylic acid for a sufficient period of time and under suitable conditions of temperature and pressure to form a reaction mixture, and ii) polymerizing said reaction mixture in the presence of a suitable catalyst for a sufficient period of time and under suitable conditions of temperature and pressure; and

C) a suitable solvent.

2. The photoresist composition according to claim 1 wherein said carbinol has the structure

(0 wherein: (a) Ri is selected from the group consisting of H, Ci -C₂o -alkyl, substituted and unsubstituted phenyl and C(O)R₈ (where R₈ is Ci - C₂o alkyl); (b) R₂ is selected from the group consisting of H and Ci -C₂o alkyl; and (c) R₃-R₇are each independently selected from the group consisting of H, Ci -C₂o alkyl, OR₉ (where R₉ is H, Ci -C₂o alkyl, esters thereof, or substituted or unsubstituted phenyl), halogen, benzotriazole, nitro, or amino, with the proviso that at least one of R3-R7 is ORg.

3. The photoresist composition according to claim 1 wherein said catalyst for preparing the alkylated polymer is a Lewis acid.

4. The photoresist composition according to claim 1 wherein the temperature for steps i) and ii) is from about 0°C to about 120°C

5. The photoresist composition according to claim 1 wherein said catalyst is selected from a group consisting of H₂SO , HCI, AICI₃, H₃PO₄, oxalic acid, SnCI , BF₃, BCI₃, paratoluene sulfonic acid, and methane sulfonic acid.

6. The photoresist composition according to claim 1 wherein the carboxylic acid is acetic acid.

7. The photoresist composition according to claim 1 wherein the catalyst is H₂SO₄.

8. The photoresist composition according to claim 1 wherein the carbinol is selected from a group consisting of 4-hydroxyphenylmethylcarbinol, 2- hydroxyphenylmethylcarbinol, 4-hydroxybenzyl alcohol, 2-hydroxybenzyl alcohol, and mixtures thereof.

9. The photoresist composition according to claim 1 wherein the carbinol is selected from a group consisting of 3-methyl-4-hydroxyphenylmethylcarbinol, 4- acetoxyphenylmethylcarbinol and 3-methyl-4-acetoxyphenylmethylcarbinol.

10. The photoresist composition according to claim 1 wherein the polyalkylated polymer has a level of sodium ions and iron ions less than 100ppb each.

11. The photoresist composition according to claim 1 wherein the polyalkylated polymer has a level of sodium ions and iron ions less than 50ppb each.

12. The photoresist composition according to claim 1 wherein the polyalkylated polymer has a level of sodium ions and iron ions less than 10ppb each.

13. The photoresist composition according to claim 1 wherein the photosensitive compound is an ester of an alcoholic or phenolic residue and a sulfonic acid or sulfonic acid derivative.

14. The photoresist composition according to claim 1 wherein the phenolic residue is selected from a group consisting of multihydroxybenzophenones, multihydroxyphenylalkanes, phenolic oligomers, and mixtures thereof.

15. The photoresist composition according to claim 1 wherein the solvent is selected from a group consisting of propylene glycol mono-alkyl ether, propylene glycol methyl ether acetate, ethyl-3-ethoxypropionate, ethyl lactate, mixtures of ethyl-3-ethoxypropionate and ethyl lactate, mixtures of ethyl-3- ethoxypropionate and ethyl lactate, butyl acetate, xylene, diglyme and ethylene glycol monoethyl ether acetate.

16. The photoresist composition according to claim 1 wherein the solvent comprises propylene glycol monomethyl ether acetate or ethyl-3-ethoxy propionate.

17. A method for producing a semiconductor device by producing a photoimage on a substrate comprising the steps of :

A) formulating a phoie esist composition according to claim 1 ; B) coating a suitable substrate with the photoresist composition and heating to substantially remove all solvent;

C) imagewise exposing the photoresist composition and developing the photoresist composition with aqueous alkaline developer; and

D) optionally heating the substrate either immediately before or after the developing step of c).

18. The method according to claim 17 wherein the photoresist is heated from about 70°C to about 120°C

19. The method according to claim 17 wherein the imagewise exposure is carried out using radiation with wavelength from about 190nm to about 440nm.

20. The method according to claim 17 wherein the aqueous alkaline developer comprises a water soluble organic amine.

21. The method according to claim 17 wherein the aqueous alkaline developer comprises tetramethyl ammonium hydroxide.