HK1077371A - Photoresist composition for deep uv radiation containing an additive - Google Patents

Description

Photoresist composition for deep UV radiation comprising additives

Technical Field

The present invention relates to novel photoresist compositions that do not experience image degradation of the photoresist in the presence of electrons or ions, particularly when viewed in a scanning electron microscope or exposed to an electron beam during curing.

Background

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 a film of a photoresist composition is first applied to a substrate material, such as silicon wafers used in the manufacture of integrated circuits. The coated substrate is then baked to evaporate any solvent in the photoresist composition and to fix the coating on the substrate. The photoresist coated on the substrate is then subjected to imagewise exposure to radiation.

Radiation exposure causes chemical conversion 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 microlithography processes. After this imagewise exposure, the coated substrate is treated with a developer solution to dissolve and remove the radiation exposed or unexposed areas of the photoresist.

The trend towards the miniaturization of semiconductor devices has led to the use of new photoresists that are sensitive to lower and lower wavelengths of radiation and also to the use of complex multilevel systems for overcoming the difficulties associated with such miniaturization.

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

On the other hand, when a positive-working photoresist composition is 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 deprotection reaction occurs), while those areas not exposed remain relatively insoluble to the developer solution. Thus, treatment of an exposed positive-working photoresist with a 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 surface is exposed.

Positive-working photoresist compositions are currently favored over negative-working photoresists because the former generally have better resolution capabilities and pattern transfer characteristics. Photoresist resolution is defined as the smallest feature that the photoresist composition can transfer from the photomask to the substrate with a high degree of image edge acuity after exposure and development. Currently in many manufacturing applications, photoresist resolution on the order of less than one micron is required. Furthermore, it is almost always desirable that the developed photoresist wall profiles be near perpendicular to the substrate. Such demarcations between developed and undeveloped areas of the photoresist coating translate into accurate pattern transfer of the mask image onto the substrate. This becomes even more demanding as the push to miniaturization reduces the critical dimensions on the device.

Photoresists sensitive to short wavelengths between about 100nm and about 300nm may also be used, where sub-half micron geometries are required. Particularly preferred for exposure below 200nm are photoresists that include a non-aromatic polymer, a photoacid generator, an optional solubility inhibitor, and a solvent.

High resolution, chemically amplified, deep ultraviolet (100-. To date, there are three major deep ultraviolet (uv) exposure techniques that provide significant advances in miniaturization, and these techniques use lasers emitting radiation at 248nm, 193nm, and 157 nm. Examples of such photoresists are given in the following patents and incorporated herein by reference, US4,491,628, US5,350,660, US5,843,624, GB232,0718, WO00/17712 and WO 00/67072. Photoresists for 248nm exposure have typically used substituted polyhydroxystyrene and its copolymers. On the other hand, since aromatics are opaque at this wavelength, photoresists for exposure at wavelengths below 200nm require non-aromatic polymers. Typically, cycloaliphatic hydrocarbons are incorporated into the polymer to replace the etch resistance of the aromatic functionality. Photoresists that have been designed for use below 200nm have heretofore used oligomers that incorporate cycloaliphatic compounds (olefins) in the polymer backbone or acrylate polymers with pendant cycloaliphatic functionality. Photoresists sensitive at 157nm may use fluorinated polymers that are substantially transparent at this wavelength.

It has been found that certain types of photoresists, particularly those developed for imaging below 200nm and lacking aromatic functionality, undergo undesirable changes in the size of the resist image when viewed in a scanning electron microscope during inspection of the imaged resist size, or exposed to electron or ion beams during curing. One aspect of this particular image distortion, commonly referred to as line width mitigation (LWS), is observed as a mitigation of lines or expansion of holes and trenches. Measurements that oftentimes image photoresist features take a significant amount of time during which image size can vary and result in erroneous measurements. As print dimensions become smaller, the effect of electrons and ions on photoresist linewidth has become a critical issue. It has been found that photoresists based on acrylate polymers are more prone to linewidth reduction than photoresists derived from cycloolefin-based photoresists.

Although the reason for LWX is not clearly understood, and without wishing to be bound by theory, those skilled in the art believe that certain mechanisms are possible when treating photoresists with electrons or ions, particularly those designed for use below 200 nm. Some possible mechanisms are cross-linking of the polymer, thermal annealing, decomposition, evaporation of components in the photoresist film, chain scission of the polymer, sputtering, etc. In past devices, improvements or process variations have helped improve LWS. The present application solves the problem by introducing additives into the photoresist, thus avoiding additional equipment and processing costs. Additives that inhibit some of the previously discussed mechanisms have been found to improve the degradation of image contours. Monomer additives, radical quenchers, and crosslinkers having aromatic functionality have been found to be particularly effective. It is an object of the present invention to reduce the effect of electrons and ions on photoresists useful for imaging below 200nm by incorporating monomer additives into the photoresist.

Summary of The Invention

The present invention relates to a photoresist composition sensitive to radiation in the deep ultraviolet, wherein the photoresist composition comprises a) a polymer that is insoluble in aqueous alkaline solutions and comprises at least one acid labile group, and further wherein the polymer is substantially non-phenolic, b) a compound capable of generating an acid upon irradiation, and c) an additive selected from the group consisting of anthracenes, substituted anthracenes, quinones, substituted quinones, crosslinkers, and iodo-substituted aromatic compounds and their derivatives. The photoresist is preferably irradiated with light having a wavelength of 193nm or 157 nm. The present invention also relates to a method of forming an image that is resistant to image degradation in the presence of electrons and ions, comprising the steps of: forming a coating of a photoresist film of the novel composition, imagewise exposing the photoresist film, developing the photoresist film and placing the imaged photoresist film in an electronic and/or ionic environment. The environment of electrons and/or ions may be a scanning electron microscope or a curing process.

Description of the invention

The present invention relates to photoresist compositions that are sensitive to radiation in the deep ultraviolet, particularly positive photoresists that are sensitive in the 100-200 nanometer (nm) range. The photoresist composition comprises a) a polymer that is insoluble in aqueous alkaline solutions and comprises at least one acid labile group, and further wherein the polymer is substantially non-phenolic, b) a compound capable of generating an acid upon irradiation, and c) an additive that reduces the effect of electrons and ions on the photoresist image. The photoresist is preferably irradiated with light having a wavelength of 193nm or 157 nm. The additive is selected from polycyclic aromatic compounds such as anthracene and anthracenal, radical quenchers such as quinone and substituted quinone, cross-linking agents, iodine-containing compounds such as iodine-substituted aromatic substances, and derivatives thereof. The invention also relates to a method of imaging the novel photoresist.

The polymers of the present invention are polymers containing groups that render the polymer insoluble in aqueous alkaline solutions, but such polymers catalytically deprotect the polymer in the presence of an acid, wherein the polymer then becomes soluble in aqueous alkaline solutions. The polymers are transparent below 200nm and are substantially non-phenolic, and acrylate and/or cyclic olefin polymers are preferred. Such polymers are, for example, but not limited to, those described in the following documents: U.S. Pat. No. 5,843,624, U.S. Pat. No. 5,879,857, WO97/33,198, EP789,278 and GB2,332,679. Non-aromatic polymers preferred for use in irradiation below 200nm are substituted acrylates, cycloolefins, substituted polyethylenes, and the like.

Acrylate-based polymers are generally based on poly (meth) acrylates containing pendant cycloaliphatic groups. Examples of pendant alicyclic groups are adamantyl, tricyclodecyl, isobornyl and mesityl. Such polymers are described in r.r.dammel et al, advances in resist technology and processing, SPIE, vol.3333, page 144, (1998). Examples of such polymers include poly (2-methyl-2-adamantane methacrylate-co-mevalonolactone methacrylate), poly (carboxy-tetracyclododecyl methacrylate-co-tetrahydropyranyl carboxy forty-dialkyl methacrylate), poly (tricyclodecyl acrylate-co-tetrahydropyranyl methacrylate-co-methacrylic acid), poly (3-oxocyclohexyl methacrylate-co-adamantyl methacrylate).

Polymers synthesized from cycloolefins, with norbornene and tetracyclododecene derivatives, can be polymerized by ring-opening metathesis, free-radical polymerization or using metal-organic catalysts. The cycloolefin derivative may also be copolymerized with maleic anhydride or with maleimide or its derivatives. Such polymers are described in the following references and incorporated herein, M-d. rahman et al, advances in resist technology and processing, SPIE, vol.3678, page 1193, (1999). Examples of such polymers include poly (t-butyl 5-norbornene-2-carboxylate-co-2-hydroxyethyl 5-norbornene-2-carboxylate-co-5-norbornene-2-carboxylic acid-co-maleic anhydride), poly (t-butyl 5-norbornene-2-carboxylate-co-isobornyl-5-norbornene-2-carboxylate-co-2-hydroxyethyl 5-norbornene-2-carboxylate-co-5-norbornene-2-carboxylic acid-co-maleic anhydride), poly (tetracyclododecene-5-carboxylate-co-maleic anhydride), and the like.

Fluorinated non-phenolic polymers for 157nm exposure also exhibit LWS and benefit from the incorporation of the additives described in the present invention. Such polymers are described in WO00/17712 and WO00/67072 and incorporated herein by reference. An example of one such polymer is poly (tetrafluoroethylene-co-norbornene-co-5-hexafluoroisopropanol-substituted 2-norbornene).

Polymers synthesized from cycloolefins and cyano-containing olefinic monomers are described in US patent application 09/854,312 and incorporated herein by reference.

The molecular weight of the polymer is optimized according to the type of chemistry used and according to the lithographic performance desired. Typically, the weight average molecular weight is 3,000-30,000 and the polydispersity is from 1.1 to 5, preferably from 1.5 to 2.5.

Although photosensitive compounds that generate an acid upon irradiation may be used, suitable examples of the acid-generating photosensitive compounds include onium salts such as bisazoonium salts, iodonium salts, sulfonium salts, halides, and esters. The onium salt is usually used in a form soluble in an organic solvent, mainly used as an iodonium or sulfonium salt, and examples thereof are diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluorobutanesulfonate, triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluorobutanesulfonate and the like. Other compounds that form an acid upon irradiation may be used, such as triazines, oxazoles, oxadiazoles, thiazoles, substituted 2-pyrones. Preference is also given to phenolic sulfonates, bissulfonylmethane or bissulfonyldiazomethane.

Particular additives incorporated into the photoresists of the invention are those that prevent degradation of the photoresist image when the photoresist image is exposed to an electronic or ionic environment. It has been unexpectedly found that certain additives reduce the degradation of the photoresist when the photoresist image is viewed in a scanning electron microscope or cured using an electron beam. Such additives are polycyclic aromatics, quinones or derivatives thereof, crosslinkers, or iodine substituted aromatics. Without limitation, examples of polycyclic aromatics can be anthracene, anthracene methanol, and anthracene aldehyde, particularly 9-anthracene methanol and 9-anthracene aldehyde; examples of quinones are hydroquinone and tert-butylhydroquinone; examples of crosslinking agents are N, O acetals such as glycolurils, specifically tetramethoxymethyl glycoluril; and an example of an iodo-substituted aromatic compound is iodobenzene, specifically 1, 4-diiodotetrafluorobenzene.

The amount of additive is 0.1 wt% to 5 wt% relative to total photoresist solids. More preferably, 0.3 wt% to 2 wt% is used.

The solid component of the present invention is dissolved in an organic solvent. The amount of solids in the solvent or solvent mixture is from about 5 wt% to about 50 wt%. The polymer may be 5 wt% to 90 wt% of the solids and the photoacid generator may be 2 wt% to about 50 wt% of the solids. Suitable solvents for such photoresists may include propylene glycol monoalkyl ether, propylene glycol alkyl (e.g., methyl) ether acetate, ethyl 3-ethoxypropionate, xylene, diglyme, amyl acetate, ethyl lactate, butyl acetate, 2-heptanone, ethylene glycol monoethyl ether acetate, and mixtures thereof.

Various other additives such as colorants, non-actinic dyes, anti-striation agents, plasticizers, adhesion promoters, coating aids, speed enhancers and surfactants may be added to the photoresist composition prior to application of the solution to the substrate. Sensitizers that transfer energy from a particular wavelength range to different exposure wavelengths may also be added to the photoresist composition. A base is also typically added to the photoresist to block the t-tops of the image surface. Examples of bases are amines, ammonium hydroxide, and photosensitive bases. Particularly preferred bases are trioctylamine, diethanolamine and tetrabutylammonium hydroxide.

The prepared photoresist composition solution can be applied to a substrate by any conventional method used in the photoresist art, including dipping, spraying, spinning, and spin coating. For example, when spin coating, the photoresist solution can be adjusted in percent solids content to provide a coating of desired thickness, given the type of spinning equipment employed 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 III/V compounds. The photoresist may also be coated over an antireflective coating.

The photoresist coatings produced by the process are particularly suitable for application to silicon/silicon dioxide wafers, such as for the production of microprocessors and other miniaturized integrated circuit components. Aluminum/aluminum oxide wafers may also be used. The substrate may also comprise various polymeric resins, particularly transparent polymers such as polyesters.

The photoresist composition solution is then applied to a substrate, and the substrate is treated at a temperature of about 70 ℃ to about 150 ℃ for about 30 seconds to about 180 seconds on a hot plate or for about 15 to about 90 minutes in a convection oven. This temperature treatment is selected to reduce the concentration of residual solvent in the photoresist while not causing substantial thermal degradation of the solid components. In general, one needs to minimize the concentration of solvent and this first temperature treatment is carried out until substantially all of the solvent is evaporated and a thin coating of the photoresist composition on the order of half a micron (micrometer) in thickness remains on the substrate. In a preferred embodiment, the temperature is from about 95 ℃ to about 120 ℃. The treatment is carried out 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 coated substrate can then be imagewise exposed to actinic radiation, e.g., ultraviolet radiation having a wavelength of from about 100nm (nanometers) to about 300nm, x-ray, electron beam, ion beam, or laser radiation, in any desired pattern, which can be produced by the use of a suitable mask, negative, stencil, template, or the like.

The photoresist is then post-exposed to a second bake or heat treatment prior to development. The heating temperature may range from about 90 ℃ to about 150 ℃, more preferably from about 100 ℃ to about 130 ℃. The heating may be performed on a hot plate for about 30 seconds to about 5 minutes, more preferably for about 60 seconds to about 90 seconds or by a convection oven for about 30 to about 45 minutes.

The exposed photoresist-coated substrate is developed to remove the imagewise exposed areas by immersion in a developing solution or by a spray development process. For example, the solution is preferably stirred by nitrogen burst stirring. The substrate is allowed to remain in the developer until all or substantially all of the photoresist coating has dissolved from the exposed areas. Developers include aqueous solutions of ammonium hydroxide or alkali metal hydroxides. One preferred developer is an aqueous solution of tetramethylammonium hydroxide. After the coated wafer is removed from the developing solution, one may perform an optional post-development heat treatment or bake to increase the coating adhesion and chemical resistance to etching conditions and other substances. The post-development heat treatment may include an oven bake or UV hardening process of the coating and substrate below the softening point of the coating. In industrial applications, particularly in the fabrication of microcircuit cells on silicon/silicon dioxide type substrates, the developed substrate may be treated with a buffered, hydrofluoric acid based etching solution or by dry etching. Prior to dry etching, the photoresist may be treated to electron beam curing to increase the dry etch resistance of the photoresist. Equipment for providing electron beam curing is commercially available, such as Electron cure from Electron Vision Corp. san Diego, CA92131^TM4000. When electron beam curing a standard photoresist, there is no loss of critical dimensions, e.g., for contact holes imaged in a standard photoresist film, the corners are rounded, which results in poor image transfer during dry etching. However, when using the novel photoresist of the present invention, the loss of critical dimensions is minimized and the contact holes are no longer round. The precise process conditions for obtaining the most efficient electron beam curing to increase dry etch resistance and/or decrease LWX are optimized depending on the equipment and photoresist used.

The following specific examples will provide detailed illustrations of methods of producing and using the 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. All parts and percentages are by weight unless otherwise indicated.

Examples

Comparative example 1

163.9g of poly (2-methyladamantyl methacrylate-co-2-mevalonolactone methacrylate), 2.76g of triphenylsulfonium nonafluorobutanesulfonate, 7.75g of a 1 wt% ethyl lactate solution of diethanolamine and 1.74g of a 10 wt% lactic acid acetic acid solution of a surfactant (fluoroaliphatic polymer ester, supplied by 3M corporation, St. Paul, Minnesota) were dissolved in 1273g of lactic acid acetic acid to obtain a resist solution. The photoresist solution was filtered using a 0.2 μm filter. Separately, a silicon substrate with an antireflective coating was prepared by spin-coating a bottom antireflective coating solution, AZ _ EXP ArF-1 b.a.r.c. (available from Clariant Corporation, Somerville, NJ08876) onto a silicon substrate and baking at 175 ℃ for 60 seconds. The thickness of the B.A.R.C. film was kept at 39 nm. The photoresist solution was then coated on the b.a.r.c. coated silicon substrate. The spin speed was adjusted so that the photoresist film thickness was 390 nm. The photoresist film was baked at 115 ℃ for 60 seconds. It was then exposed on a 193nm ISI micro stepper projector exposure machine (digital aperture of 0.6 and coherence of 0.7) using chromium on a quartz binary mask. After exposure, the wafer was post-exposed to 110 ℃ for 60 seconds. Development was carried out for 60 seconds using a 2.38 wt% aqueous solution of tetramethylammonium hydroxide. The line and space patterns were then observed on a scanning electron microscope. The sensitivity of the photoresist formulation was 20mJ/cm²And a linear resolution of 0.13 μm.

Comparative example 2

19.85g of a polymer (prepared from 100 parts of maleic anhydride, 35 parts of tert-butyl 5-norbornene-2-carboxylate, 10 parts of 2-hydroxyethyl 5-norbornene-2-carboxylate, 5 parts of 5-norbornene-2-carboxylic acid, 25 parts of 2-methyladamantyl methacrylate, and 25 parts of 2-hydroxypentanoate lactone methacrylate), 0.33g of triphenylsulfonium nonafluorobutanesulfonate, 6.32g of a 1 wt% Propylene Glycol Monomethyl Ether Acetate (PGMEA) solution of trioctylamine and 0.18g of a 10 wt% Propylene Glycol Monomethyl Ether Acetate (PGMEA) solution of a surfactant (fluoroaliphatic polymer ester, supplied by 3M Corporation, Minnesota) were dissolved in 123g of PGMEA. The solution was filtered using a 0.2 μm filter and processed in a similar manner as described in comparative example 1, except that the photoresist film was baked at 110 ℃ for 90 seconds, post-exposure baked at 130 ℃ for 90 seconds, and developed for 30 seconds. The sensitivity of the formulation was 17mJ/cm²And a linear resolution of 0.09 μm.

Example 1

0.01725g of 9-anthracenemethylol were dissolved in 30g of the resist prepared in comparative example 1. The solution was filtered using a 0.2 μm filter and processed in a similar manner as described in comparative example 1. At 24mJ/cm²A linear resolution of 0.12 μm was obtained at the dose of (2).

Example 2

0.01725g of tert-butylhydroquinone were dissolved in 30g of the photoresist prepared in comparative example 1. The solution was filtered using a 0.2 μm filter and processed in a similar manner as described in comparative example 1. At 28mJ/cm²A linear resolution of 0.14 μm was obtained at the dose of (2).

Example 3

0.01725g of tetramethoxymethyl glycoluril were dissolved in 30g of the photoresist prepared in comparative example 1. Mixing the solution withFiltered through a 0.2 μm filter and processed in a similar manner as described in comparative example 1. At 66mJ/cm²A linear resolution of 0.14 μm was obtained at the dose of (2).

Example 4

0.0135g of 9-anthracenal was dissolved in 20g of the resist prepared in comparative example 2. The solution was filtered using a 0.2 μm filter and processed in a similar manner as described in comparative example 2. At 18.5mJ/cm²A linear resolution of 0.08 μm was obtained at the dose of (2).

Example 5

0.0237g of 1, 4-diiodotetrafluorobenzene was dissolved in 20g of the photoresist prepared in comparative example 2. The solution was filtered using a 0.2 μm filter and processed in a similar manner as described in comparative example 2. At 18mJ/cm²A linear resolution of 0.10 μm was obtained at the dose of (2).

Example 6

5.89g of a polymer (prepared from 100 parts of maleic anhydride, 35 parts of tert-butyl 5-norbornene-2-carboxylate, 10 parts of 2-hydroxyethyl 5-norbornene-2-carboxylate, 5 parts of 5-norbornene-2-carboxylic acid, 25 parts of 2-methyladamantyl methacrylate, and 25 parts of 2-hydroxypentanoate lactone methacrylate), 0.154g of diphenyliodonium nonafluorobutanesulfonate, 2.80g of a 1 wt% PGMEA (propylene glycol monomethyl ether acetate) solution of trioctylamine and 0.054g of a 10 wt% PGMEA solution of a surfactant were dissolved in 38g of PGMEA. The solution was filtered using a 0.2 μm filter and processed in a similar manner as described in comparative example 2. At 28mJ/cm²A linear resolution of 0.08 μm was obtained at the dose of (2).

Example 7

0.0135g of 9-anthracenemethanol was dissolved in 20g of the photoresist prepared in example 8. The solution was filtered using a 0.2 μm filter and processed in a similar manner as described in comparative example 2. At 27mJ/cm²A linear resolution of 0.08 μm was obtained at the dose of (2).

Linewidth mitigation (LWS) measurement:

linewidth reduction of photoresist critical dimensions during scanning electron microscopy (CD SEM) measurements was performed on KLA 8100 CD SEM. The rate of line width change over time was automatically measured at 600V acceleration voltage using a 50% threshold. The average of the two measurements was taken for a 0.15 μm line. The percent change in critical dimension was measured immediately and after 30 seconds. The results are summarized in table 1 for all of the above examples.

TABLE 1 Change in Critical Dimension (CD) after 30 seconds in CD SEM

Example No.	Reduction of CD (%)
		Comparative example 1	89.6
Comparative example 2	89.5
		Example 1	94.0
Example 2	91.0
		Example 3	91.2
Example 4	92.1
		Example 5	94.1
Example 6	91.5
		Example 7	93.3

As shown in table 1, the photoresists without additives, as in comparative examples 1 and 2, showed a critical dimension reduction of greater than 10% after 30 seconds inspection time in CD SEM. However, the novel photoresists of the invention retain more than 91% of the critical dimension when processed under similar conditions. A minimum reduction in critical dimensions is preferred. Preferably, the reduction in critical dimension is less than 10%.

Claims (13)

1. A photoresist composition for exposure below 200nm and capable of reducing the effect of electrons and ions on photoresist degradation comprising:

a) a polymer that is insoluble in an aqueous alkaline solution and comprises at least one acid labile group, and further wherein the polymer is substantially non-aromatic;

b) a compound capable of generating an acid upon irradiation; and

c) an additive selected from the group consisting of polycyclic aromatics, quinones, substituted quinones, crosslinkers, and iodo-substituted aromatics.

2. The photoresist composition according to claim 1, where the additive is selected from the group consisting of anthracene, anthracenemelane, hydroquinone, t-butylhydroquinone, glycoluril, and iodobenzene.

3. The photoresist composition according to claim 1, where the additive is selected from the group consisting of 9-anthracenemethanol, 9-anthracenal, tetramethoxymethyl glycoluril, and 1, 4-diiodotetrafluorobenzene.

4. The photoresist composition according to claim 1, where the polymer comprises a cycloaliphatic group.

5. The photoresist composition according to claim 4, where the polymer contains an acrylate backbone with pendant cycloaliphatic groups.

6. The photoresist composition according to claim 4, where the polymer contains a backbone of cycloaliphatic groups.

7. The photoresist composition according to claim 4, where the polymer is a copolymer of maleic anhydride and a substituted and/or unsubstituted cycloaliphatic monomer.

8. The photoresist composition according to claim 1, where the polymer does not contain aromatic groups.

9. A method of forming a photoresist image comprising the steps of:

a) forming a coating of the photoresist of claim 1 on a substrate;

b) imagewise exposing the coating of photoresist; and

c) the photoresist coating is developed using an aqueous alkaline developer.

10. The method of claim 9, wherein the imagewise exposure is at a wavelength of 193nm or 157 nm.

11. The method of claim 9, wherein the basic aqueous solution comprises tetramethylammonium hydroxide.

12. The method of claim 9, further comprising an electronic curing step.

13. The method of claim 9, further comprising inspection of the photoresist image in a scanning electron microscope.