KR100737553B1 - High sensitivity resist compositions for electron-based lithography - Google Patents

Abstract

The resist composition of the present invention has an acid sensitive imaging polymer and a radiation sensitive acid generator component, wherein the radiation sensitive acid generator component is (i) a first radiation sensitive acid generator selected from the group consisting of dissolution-inhibiting acid generators, and (ii ) A second radiation sensitive acid generator selected from the group consisting of an unprotected acid group-functionalized acid generator and an acid labile group-protected acid group-functionalized radiation sensitive acid generator, which includes EPL, EUV, soft It allows the formation of high sensitivity resists suitable for use in x-rays, and other low energy intensity lithography imaging applications. The resist composition may likewise be useful for other lithography processes.

Resist, composition, sensitivity, lithography

Description

High sensitivity resist composition for electromagnetic lithography {HIGH SENSITIVITY RESIST COMPOSITIONS FOR ELECTRON-BASED LITHOGRAPHY}

The present invention relates to a highly sensitive resist composition for electromagnetic lithography.

In the field of semiconductor manufacturing, there is a continuing need to reduce the size of devices. This process leads to the need for lithography techniques to produce smaller feature sizes.

In lithography processes using wave radiation (e.g., ultraviolet, deep ultraviolet (248 nm-KrF), far ultraviolet (193 nm-ArF)), the smallest feature size that can be resolved is imaging It is related to the wavelength of the radiation. Practical use of the 193 nm lithography process is beginning in the microelectronics industry. Lithographic processes and tools using 157 nm emission are planned, but are still far from commercial practice. To some extent, feature size resolution at a given imaging emission wavelength can be achieved by alternative techniques such as bilayer lithography processes and / or mask-related lithography techniques (eg, phase shift masks, etc.). Can be enhanced using. Nevertheless, it is anticipated that additional resolution enhancement capabilities (eg, 50 nm or less) will be required for so-called next generation lithography or NGL. Possible routes to NGL include (a) so-called extreme ultraviolet (EUV) emission lithography, (b) soft x-ray lithography, and (c) electron projection lithography (EPL).

Electron beam imaging has been used in the microelectronics industry for many years for the manufacture of masks for conventional photolithography and low volume / low throughput direct-write wafer applications. In these uses, a relatively high energy narrow electron beam is precisely focused into a selected area of the resist layer on the mask blank or semiconductor wafer. The mask-manufacturing / direct-writing process generally records precisely the required pattern across the resist surface and transfers sufficient energy to the required area of the resist layer for subsequent development of the exposed pattern, so the precise control of the beam position is generally Is very slow. Examples of highly suitable resist materials for use in these electron beam processes are disclosed in US Pat. Nos. 6,043,003 and 6,037,097, which are incorporated herein by reference.

Electronic projection lithography (EPL) for NGL is described in US Pat. No. 4,554,458, which is incorporated herein by reference; 5,866,913; 5,866,913; 6,069,684; 6,069,684; No. 6,296,976; And 6,355,383. In a typical lithography process, EPL projects the imaging radiation through a patterned mask, which includes patterned exposure of the resist layer to the imaging radiation. In the case of EPL, electron projection radiation is imaging radiation. Exposure (optionally followed by baking) involves chemical reactions at exposed areas of the resist that change the solubility of the exposed areas of the resist. Thereafter, a suitable developer, generally an aqueous basic solution, is used to selectively remove the resist in the exposed areas (positive-tone resist) or in the unexposed areas (negative-tone resist). The finite pattern thus leaves traces on the wafer by etching out areas that are not protected by the resist in a dry or wet etch process.

Unfortunately, EPL provides low intensity imaging radiation because the high throughput required for commercial semiconductor processes cannot be achieved with the resist materials currently used. EUV lithography and soft x-ray lithography also have similar problems due to the lack of intensity of imaging radiation. Typically, conventional resist materials have sufficient sensitivity, exposure dose latitude, stability (eg shelf-life, resistance to phase separation, stability to vacuum exposure, etc.) Lack of this. Thus, there is a need for new resist compositions that can be used for EPL, EUV, soft x-ray, and other low energy intensity lithography imaging applications.

The present invention provides an improved resist composition and lithographic method using the resist composition of the present invention.

The resist composition of the present invention

(Iii) a first radiation sensitive acid generator selected from the group consisting of dissolution-inhibiting acid generators, and

(Ii) a second radiation sensitivity selected from the group consisting of unprotected acidic group-functionalized acid generators and acid labile group-protected acidic group-functionalized radiation sensitive acid generators Acid-catalyzed resists characterized by the presence of a radiation sensitive acid generator comprising an acid generator.

The combination of acid generators generally allow the formation of high sensitivity resists suitable for use in EPL, EUV, soft x-ray, and other low energy intensity lithography imaging applications. The resist composition can likewise be used in other lithography processes.

In another aspect, the invention comprises a resist composition, the composition comprising the following components:

(a) an imaging polymer, and

(b) a radiation sensitive acid generator component comprising the following component:

(Iii) a first radiation sensitive acid generator selected from the group consisting of dissolution-inhibiting acid generators, and

(Ii) a second radiation sensitive acid generator selected from the group consisting of unprotected acid group-functionalized generators and acid labile group-protected acid group-functionalized acid generators.

The imaging polymer preferably comprises a ketal-functionalized acid sensitive polymer. The second acid generator includes an acidic moiety selected from the group consisting of phenolic, carboxylic and fluoroalcoholic acidic moieties. The resist composition preferably comprises at least about 4% by weight radiation sensitive acid generator component based on the weight of the imaging polymer.

In another aspect, the present invention includes a method of forming a patterned material structure on a substrate using the resist composition of the present invention, the method comprising the following steps:

(A) providing a layer of material on the substrate;

(B) applying a resist composition of the present invention on the substrate to form a resist layer on the substrate;

(C) patternwise exposing the substrate to radiation so that acid is generated by an acid generator of the resist in the exposed region of the resist layer by the radiation;

(D) contacting an aqueous alkaline developer to the substrate to selectively dissolve the exposed area of the resist layer by the developer to reveal a patterned resist structure; And

(E) etching the material layer through a space with a resist structure pattern to transfer the resist structure pattern to the material layer.

The imaging radiation is preferably electron projection, EUV or soft x-ray radiation. The material to be patterned is preferably selected from the group consisting of organic dielectrics, semiconductors, ceramics and metals.

These and other aspects of the invention are discussed in further description below.

The present invention provides an improved resist composition and lithographic method using the resist composition of the present invention. The resist composition of the present invention

(Iii) a first radiation sensitive acid generator selected from the group consisting of dissolution-inhibiting acid generators, and

(Ii) the presence of a radiation sensitive acid generator comprising a second radiation sensitive acid generator selected from the group consisting of an unprotected acid group-functionalized acid generator and an acid labile group-protected acid group-functionalized acid generator. Characterizing an acid-catalyzed resist.

The combination of acid generators allows the formation of high sensitivity resists suitable for use in EPL, EUV, soft x-ray, and other low energy intensity lithography imaging applications. The resist composition may likewise be useful in other lithography processes. The invention also includes a method of using these resists to pattern the material.

The resist composition of the present invention generally includes:

(a) acid-sensitive imaging polymers, and

(b) a radiation sensitive acid generator component comprising the following component:

(Iii) a first radiation sensitive acid generator selected from the group consisting of dissolution-inhibiting acid generators, and

(Ii) a second radiation sensitive acid generator selected from the group consisting of unprotected acid group-functionalized generators and acid labile group-protected acid group-functionalized acid generators.

The invention is not limited to any specific acid-sensitive imaging polymer. The acid-sensitive imaging polymer may comprise pendant acid labile protecting groups that inhibit dissolution of the resist in aqueous alkaline solution, and (b) pendant polar groups that promote dissolution of the resist composition in aqueous alkaline solution (e.g., hydroxyl, carr). It is preferable that it is a polymer which has a compound, a fluoro alcohol, etc.). Preferred acid-labile protecting groups are acid labile selected from the group consisting of tertiary alkyl (or cycloalkyl) carboxylic esters (e.g. t-butyl, methyl cyclopentyl, methyl cyclohexyl, methyl adamantyl), ketals and acetals It includes residues. More preferably the acid labile moiety is ketal, most preferred is methoxycyclopropanyl, ethoxycyclopropanyl, butoxycyclohexanyl, methoxycyclobutanyl, ethoxycyclobutanyl, methoxycyclopentanyl, ethoxy Cyclic aliphatic ketals such as cyclopentanyl, methoxycyclohexanyl, ethoxycyclohexanyl, propoxycyclohexanyl, methoxycycloheptanyl, methoxycyclooctanyl or methoxyadamantyl. Preferred imaging polymers are described in US Pat. Nos. 6,037,097 and 6,043,003, which are incorporated herein by reference.

The radiation acid generator component comprises a combination of radiation sensitive acid generators. The first radiation sensitive acid generator is selected from the group consisting of dissolution-inhibiting acid generators. These acid generators are dissolved-suppressed in the absence of imaging radiation required to cause acid formation. Dissolution-inhibiting acid generators are generally characterized by (a) an acidic functional group, and (b) an acid labile group-protected acidic functional group. Examples of suitable radiation-sensitive dissolution-inhibiting acid generators include the following versions of acid generators without (a) acidic functional groups and (b) acid labile group-protected acid functional groups: triaryl Sulfonium hexafluoroantimonate, diaryliodonium hexafluoroantimonate, hexafluorobirate, triflate, perfluoroalkane sulfonate (e.g., perfluoromethane sulfonate, purple Fluorobutane, perfluorohexane sulfonate, perfluorooctane sulfonate, etc.), sulfonic acid ester of hydroxyimide, N-sulfonyloxynaphthalimide (N-camphorsulfonyloxynaphthalimide, N Onium salts such as -pentafluorobenzenesulfonyloxynaphthalimide), aa 'bis-sulfonyl diazomethane, naphthoquinone-4-diazide, alkyl disulfone and the like. Preferred dissolution inhibiting acid generators are triphenyl sulfonium triflate. The present invention is not limited to any specified dissolution-inhibiting acid generator.

The second radiation sensitive acid generator is selected from the group consisting of unprotected acid group-functionalized acid generators and acid labile group-protected acid group-functionalized acid generators. In an unprotected state, the second acid generator promotes dissolution of the resist in an aqueous alkaline solution. The acidic group-functionalized acid generators preferably have an acidic functional group having a pKa of about 13 or less, more preferably about 10 or less. Acidic functional groups are preferably selected from the group consisting of phenolic residues, carboxyl residues and fluoroalcohol residues. Acid labile group-protected acidic group-functionalized acid generators provide acidic functionality (preferably selected from the group consisting of phenolic residues, carboxyl residues and fluol alcohol residues) by reaction with an acid. Examples of acid labile group-protected acid group-functionalized acid generators are disclosed in US Pat. Nos. 5,374,504 and 5,191,124, the disclosures of which are incorporated herein by reference. Preferred second acid generators are dimethyl (3,5-dimethyl) -4-hydroxyphenyl sulfonium perfluororubutane sulfonate whose structure is as shown below:

The resist composition of the present invention typically comprises a solvent prior to their application to the required substrate. The solvent can be any solvent commonly used in acid-catalyzed resists without overly adversely affecting the performance of the resist composition. Preferred solvents are propylene glycol monomethyl ether acetate (PGMEA) and cyclohexanone.

The compositions of the present invention may further comprise minor amounts of auxiliary components known in the art, such as dyes / photosensitive agents, basic additives and the like. Preferred basic additives are bases which remove traces of acid without unduly affecting the performance of the resist. Preferred basic additives are tertiary alkyl amines, aromatic amines or tetraalkyl ammonium hydroxides such as t-butyl ammonium hydroxide (TBAH). Preferably, the unexposed resist composition of the present invention is substantially insoluble in aqueous alkaline solutions commonly used to develop lithographic images.

The resist composition of the present invention preferably comprises about 0.5 to 20% by weight of acid generator components (based on the total weight of the imaging polymer in the composition), more preferably about 4 to 20% by weight, most preferably about 7 to 20% by weight. The weight ratio of the first acid generator to the second acid generator is preferably about 5: 1 to 1: 5, more preferably about 3: 1 to 1: 3, most preferably about 2: 1 to 1: 2 to be. The acid generator component preferably results in a resist composition having imaging energy dose requirements for high KeV (eg, about 50-200 KeV) electron sources of less than about 15 μC / cm 2. And more preferably less than about 10 μC / cm 2, most preferably less than about 5 μC / cm 2. At low KeV (eg, about 500 eV to 10 KeV) electron sources, the resist preferably has an imaging energy dose requirement of less than about 2 μC / cm 2, and more preferably less than about 1 μC / cm 2. In radiation sources such as EUV, the resist composition of the present invention preferably has an imaging energy dose requirement of less than about 5 mJ / cm 2, more preferably less than about 2 mJ / cm 2, most preferably less than about 1 mJ / cm 2. to be. If a solvent is present, it is preferred that the entire composition contains about 50 to 90 weight percent solvent. The composition preferably contains about 1% by weight or less of the basic additive based on the total weight of the polymeric component.

The resist composition of the present invention can be prepared by combining polymeric components, acid generators and other desired components using conventional methods. Resist compositions that can be used in the lithographic process will generally have a significant amount of solvent.

The resist composition of the present invention is particularly useful for lithographic processes used in the manufacture of integrated circuits on semiconductor substrates. The composition is particularly useful for lithographic processes using electron beam projection radiation or other low energy intensity sources (eg EUV, soft x-rays, etc.). If the use of other imaging radiation (eg mid-UV, 248 nm deep UV, 193 nm UV, or x-rays) is desired, the compositions of the present invention may be added to the composition by adding an appropriate dye or By controlling the amount of acid generator component and / or by removing residues that may affect the optical density at a particular emission wavelength.

The present invention includes a method of producing a patterned material structure on a substrate using the resist composition of the present invention, the method comprising the following steps:

(A) providing a layer of material on the substrate;

(B) applying a resist composition of the present invention on the substrate to form a resist layer on the substrate;

(C) patternwise exposing the substrate to radiation so that acid is generated by an acid generator of the resist in the exposed region of the resist layer by the radiation;

(D) contacting the aqueous alkaline developer to the substrate to selectively dissolve the exposed area of the resist layer by the developer solution to reveal a patterned resist structure; And

(E) etching the material layer through the space into the resist structure pattern to transfer the resist structure pattern to the material layer.

The material layer of the substrate is preferably selected from the group consisting of organic dielectrics, metals, ceramic semiconductors or other materials according to the manufacturing process steps and the required materials tailored for the final product. The material to be patterned can be applied using any suitable technique. The substrate is preferably a semiconductor wafer or a glass (eg fused quartz) plate.

If desired, an antireflective coating (ARC) may be applied over the material layer prior to application of the resist layer. The ARC layer can be any conventional ARC that is compatible with acid catalyzed resist, the underlying material layer, subsequent processes, and the like.

Typically, the solvent-containing resist composition can then be applied onto the required substrate using spin coating or other techniques. The substrate with the resist coating is then baked preferably to remove the solvent and improve the adhesion of the resist layer (pre-exposure bake). It is preferred that the thickness of the applied layer is as thin as possible, provided that (a) the thickness is substantially uniform, and (b) a subsequent process in which the resist layer transfers the lithographic pattern to the underlying substrate material layer (typically reactive ion etching). Sufficient to withstand. The pre-exposure bake step is preferably performed for about 10 seconds to 15 minutes, more preferably about 15 seconds to 1 minute. The pre-exposure bake temperature may vary depending on the glass transition temperature of the resist.

After removal of the solvent, the resist layer is then patternwise exposed to the desired imaging radiation. Preferably, the imaging radiation is a low intensity energy source such as electron projection radiation, EUV or soft x-rays. (a) The total exposure energy dose for high KeV (eg, about 50 to 200 KeV) electron sources is preferably less than about 15 μC / cm 2, more preferably less than about 10 μC / cm 2, and less than about 5 μC / cm 2. Most preferred; (b) For low KeV (eg, about 500 eV to 10 KeV) electron sources, the energy dose is preferably less than about 2 μC / cm 2, more preferably less than about 1 μC / cm 2; For EUV, the imaging energy dose is preferably less than about 5 mJ / cm 2, more preferably less than about 2 mJ / cm 2, and most preferably less than about 1 mJ / cm 2.

After the required patterned exposure, the resist layer is typically baked to further complete the acid-catalyzed reaction and to enhance the contrast of the exposed pattern. Post-exposure bake is preferably performed at about 60 to 175 ° C, more preferably about 90 to 160 ° C. The post-exposure bake is preferably performed for about 30 seconds to 5 minutes.

After the post-exposure bake, a resist structure with the required pattern is obtained (developed) by contacting the resist layer with an alkaline solution that selectively dissolves the resist regions exposed to radiation. Preferred alkaline solutions (developers) are aqueous solutions of tetramethyl ammonium hydroxide. Preferably, the resist composition of the present invention can be developed with conventional 0.26N aqueous alkaline solution. The resist composition of the present invention can also be developed using 0.14N or 0.21N or other aqueous alkaline solutions. The resist structure obtained on the substrate is then typically dried to remove any remaining developer solvent.

The pattern from the resist structure can be transferred to the material of the underlying substrate (eg, organic dielectric, ceramic, metal, semiconductor, etc.). Typically, delivery can be accomplished by reactive ion etching or some other etching technique. Any suitable etching technique can be used. In some embodiments, hard masks may be used beneath the resist layer to facilitate the transfer of the pattern to additional base material layers or sections. Examples of such processes are described in US Pat. No. 4,855,017; No. 5,362,663; No. 5,429,710; 5,562,801; 5,562,801; 5,618,751; 5,618,751; No. 5,774,376; 5,801,094; 5,821,469, and 5,948,570, the disclosures of which are incorporated herein by reference. Other examples of pattern transfer processes are disclosed in chapters 12 and 13 of "Semiconductor Lithography, Principles, Practices, and Materials" by Wayne Moreau, Plenum Press, (1998), which are hereby incorporated by reference. Included. It is to be understood that the present invention is not limited to any specific lithography technique or device structure.

Example 1

Synthesis of Dimethyl (3,5-dimethyl) -4-hydroxyphenyl sulfonium perfluorobutane sulfonate (DMPHS PFBUS)

8 ml of Eaton's Reagent (Aldrich, 7.7% by weight of P ₂ O _{5 in} methanesulfonic acid) was added via an addition funnel to a 50 ml three-necked round bottom equipped with thermocouple, N ₂ inlet and magnetic stirrer. To a mixture of 2.44 g (0.02 mole) 2,6-dimethylphenol and 1.56 g (0.02 mole) dimethyl sulfoxide in the flask was added. The rate of addition was adjusted so that the temperature of the mixture did not rise above 60 ° C. during the addition. After the exothermic reaction had subsided, the reaction mixture was stirred at room temperature for 2 hours and poured into 40 ml of distilled water. The solution was neutralized to pH = 7 by addition of ammonium hydroxide solution. The resulting solution was stirred for half an hour at room temperature and then filtered through filter paper to remove brown oil by-products. The filtrate was added dropwise with stirring in a solution of 6.76 g (0.02 mol) of potassium perfluorobutanesulfonate (KPFBuS) dissolved in 70 mL water. The mixture was stirred further overnight. The white precipitate was collected by suction filtration and washed three times with water and ether. The crude product was redissolved in 15-20 mL ethyl acetate. To this solution was added 200-300 mg of aluminum oxide (activated, basic). The mixture was rolled up on a roller overnight and then filtered through celite. The filtrate was precipitated in 100 ml ether with stirring. The white precipitate was collected and additionally washed three times with ether. Final yield: 2.2 g (23%)

Example 2

Synthesis of Dimethyl Phenylsulfonium Perfluorobutane Sulfonate (DMPS PFBUS)

A solution of 4.07 g (0.01 mol) of silver perfluorobutane sulfonate dissolved in 30 ml of nitromethane was dissolved at 1.24 g (0.01 mol) of thioanisol and 4.26 g in 25 ml of nitromethane at room temperature. (0.03 mol) was added dropwise in a mixture containing methyl iodide. The resulting mixture was stirred at rt for 15 h. The reaction mixture was filtered through celite to remove white precipitate. The filtrate was concentrated to about 10 mL and precipitated with 120 mL diethyl ether. White solid was collected by reduced pressure filtration. The crude product was redissolved in 15-20 mL ethyl acetate. To this solution was added 200-300 mg of aluminum oxide (activated, basic). The mixture was rolled up on a roller overnight and then filtered through celite. The filtrate was precipitated with 100 mL of ether with stirring. The white precipitate was collected and additionally washed three times with ether. Final yield: 3.64 g (83%). The product was identified as dimethyl phenyl sulfonium perfluorobutane sulfonate by NMR spectroscopy.

Example 3

Synthesis of Polyvinylphenol (monodisperse polymer) (PHMOCH) protected with methoxycyclohexane (MOCH)

150 g of propylene glycol methyl ether acetate (PGMEA) was added to 50 g of polyvinylphenol (VP5000 from Tomen) with stirring until a clear solution was obtained. The solution was then combined with approximately 35 mg of oxalic acid. After dissolving the acid, 18.5 g of 1-methoxycyclohexane was added into the solution and allowed to react at room temperature with stirring overnight. The reaction was then stopped with 6 g of basic activated aluminum oxide. A protection level of 25% on phenolic groups was determined by C ¹³ NMR.

Example 4 (comparative)

Resist with Single Dissolution Inhibitory Acid Generator (TPS TRF)

Partially protected polymer of Example 3, PHMOCH in 0.14 wt% (relative to polymer) tetrabutyl ammonium hydroxide (TBAH), 0.7 wt% triphenylsulfonium triflate (TPS TRF) in PGMEA solvent ) And 200-400 ppm FC-430 surfactant (3M Company) to obtain a resist formulation. The total solids weight content in the solution was about 12%. Similar formulations were made with the loading of TPS TRF shown in the table below. The resist was spin coated onto each HMDS-primed wafer. The coated wafers were baked for 1 minute on a 110 ° C. hotplate. The resist was exposed to an IBM-built high throughput e-beam projection system at 75 kV. After exposure, the resist was baked at 110 ° C. for 1 minute before developing for 60 seconds with 0.263 N TMAH. The table below presents the dose for resolving 100 nm line / space images with different TPS TRF loadings.

TPS TRF Loading Dose for resolving 100 nm l / s Image profile 0.7 wt% 40μC / ㎠ Straight 1.4 wt% 24μC / ㎠ Straight 3 wt% 12μC / ㎠ Straight 5 wt% 9μC / ㎠ Slight foot 6% by weight 7μC / ㎠ Undercut profile 7 wt% 5μC / ㎠ Phase separation on coated film

Example 5 (comparative)

Resist with Single Dissolution Promoting Acid Generator

A resist formulation was obtained in the manner of Example 4, but the DMPHS PFBUS of Example 1 was used in place of TPS TRF. The loading of the DMPHS PFBUS is shown in the table below based on the weight of the imaging polymer. The resist was spin coated onto each HMDS-primed wafer. The wafer was baked on a hotplate at 110 ° C. for 1 minute. The resist-coated wafers were exposed at 25 kV in an ElectronCure ^™ -200M float exposure tool manufactured by Electron Vision Group. After exposure, the resist was baked at 110 ° C. for 1 minute before developing for 60 seconds with 0.263 N TMAH. The table below presents the doses to clear large squares exposed by different DMPHS PFBUS loadings.

DMPHS PFBUS Loading E _o , dose clearing 0.82 wt% 12μC / ㎠ 3.28% by weight 4μC / ㎠ 4.91% by weight 3μC / ㎠ 6.55 wt% 2.5μC / ㎠ 8.19% by weight 2.1μC / ㎠ 12.28% by weight 1.5 μC / cm 2 (started to see extra thinning)

Example 6

Resist with mixed acid generators (DMPS PFBUS and DMPHS PFBUS) according to the invention

A resist formulation was obtained in the manner of Example 4, but a combination of DMPHS PFBUS of Example 1 and DMPS of Example 2 was used in place of TPS TRF. The loading of the acid generator is shown in the table below based on the weight of the imaging polymer. The resist was spin coated onto each HMDS-primed wafer. The resist coated wafers were baked on a hotplate at 110 ° C. for 1 minute. The resist-coated wafers were exposed using an IBM-built 25 kV Gaussian-beam system (FELS). After exposure, the resist was baked at 110 ° C. for 1 minute before developing for 60 seconds with 0.263 N TMAH. The table below shows dose and image profiles for resolving 150 nm l / s images with different DMPS PFBUS and DMPHS PFBUS loadings.

Sample DMPS PFBUS Loading DMPHS PFBUS Loading Dose for resolving 100 nm l / s Image profile 2x DMPS (1/0) (comparative) 1.49 wt% 0% by weight 4.5μC / ㎠ Undercut Mix a (3/1) 0.56% by weight 0.82 wt% 5μC / ㎠ Square and straight Mix b (1/1) 0.74% by weight 1.64 wt% 5μC / ㎠ Square and straight Mix c (1/3) 0.37 wt% 2.45 wt% 5μC / ㎠ Square and straight 4x DMPHS (0/1) (comparative) 0% by weight 3.27% by weight 5μC / ㎠ Slight rounding at the top

Example 7

Resist with mixed acid generators (TPS TRF and DMPHS PFBUS) according to the invention

A resist formulation was obtained in the manner of Example 4, but the combination of DMPHS PFBUS and TPS TRF of Example 1 was used in place of TPS TRF. The loading of the acid generator is shown in the table below based on the weight of the imaging polymer. The resist was spin coated onto each HMDS-primed wafer. The resist coated wafers were baked on a hotplate at 110 ° C. for 1 minute. The resist-coated wafers were exposed using an IBM-built 25 kV Gaussian-beam system (FELS). After exposure, the resist was baked at 110 ° C. for 1 minute before developing for 60 seconds with 0.263 N TMAH. The table below presents profiles for 150 nm and 200 nm l / s images with different TPS TRF and DMPHS PFBUS loading at both 1.5 μC / cm 2 and 2.0 μC / cm 2.

Sample TPS TRF Loading DMPHS PFBUS Loading Image profile at 1.5 μC / cm 2 Image profile at 2.0 μC / cm 2 8x TPS TRF (1/0) (comparative) 5.6 wt% 0% by weight Undercut Undercut Mix d (3/1) 4.2 wt% 3.28% by weight Slightly undercut Slightly undercut Mix e (1/1) 2.8 wt% 6.55 wt% Square and straight Square and straight Mix f (1/3) 1.4 wt% 9.83% by weight Square and straight Square and straight 16x DMPHS PFBUS (0/1) (comparative) 0% by weight 13.10% by weight Severe rounding and film loss Severe rounding and film loss

Example 8

Optimized Formulations

Resist performance characteristics (e.g., the dose range (dose latitude), resist profile, sensitivity, and E _o / E _CD related to the unexposed dissolution) a combination of an acid generator in the studies in Example 3 of the imaging polymer as in Example 7, Water was used to determine the optimal composition. From this study, a composition with 0.28 wt% TBAH, 7 wt% TPS TRF and 7.37 wt% DMPHS PFBUS had the best overall performance (with a vertical resist profile, 31% dose range, 7.4 μs / sec unexposed dissolution rate, 0.74 E _o / E _size and sensitivity of 0.39 mC / cm 2).

Wafers coated with the formulations obtained in the manner of Example 4 were photographed in a soft x-ray (1.1 nm wavelength) lithography tool from JMAR Technology Inc. With the use of soft x-rays, the resist of the present invention required a dose of less than 15 mJ / cm 2. Commercial resists have exposure dose requirements ranging from 50 to 90 mJ / cm 2 for the same soft x-ray exposure process.

Claims (10)

(a) a ketal functionalized acid sensitive polymer, and (b) a radiation sensitive acid generator component, wherein the radiation sensitive acid generator component (Iii) a first radiation sensitive acid generator selected from the group consisting of an acidic functional group and a dissolution-inhibiting acid generator having no acid labile group-protected acidic functional group, and (Ii) a second radiation sensitive acid generator selected from the group consisting of unprotected acidic group-functionalized radiation sensitive acid generators, wherein the acidic residues are selected from the group consisting of carboxyl residues and fluoroalcohol residues; Resist composition comprising. delete delete delete The resist composition of claim 1, wherein the resist composition contains at least 4% by weight of the radiation sensitive acid generator component based on the weight of the ketal functionalized acid sensitive polymer. The resist composition of claim 1, wherein the first and second acid generators are present in a molar ratio of 5: 1 to 1: 5. A method of forming a patterned material structure on a substrate, wherein the material is selected from the group consisting of organic dielectrics, semiconductors, ceramics, and metals. (A) providing a layer of material on the substrate; (B) applying a resist composition to form a resist layer on the substrate, the resist composition comprising a ketal functionalized acid sensitive polymer and a radiation sensitive acid generator component, wherein the radiation sensitive acid generator component (Iii) a first radiation sensitive acid generator selected from the group consisting of an acidic functional group and a dissolution-inhibiting acid generator having no acid labile group-protected acidic functional group, and (Ii) a second radiation sensitive acid generator selected from the group consisting of unprotected acidic group-functionalized acid sensitive acid generators, wherein the acidic residues are selected from the group consisting of carboxylic and fluoroalcohol residues; box; (C) patternwise exposing the substrate to radiation to generate acid by an acid generator of the resist in the exposed region of the resist layer by the radiation; (D) contacting the aqueous alkaline developer to the substrate to selectively dissolve the exposed area of the resist layer by the developer solution to reveal a patterned resist structure; And (E) etching the material layer through a space with a resist structure pattern to transfer the resist structure pattern to the material layer. 8. The method of claim 7, wherein at least one intermediate layer is provided between the material layer and the resist layer, and step (E) comprises etching through the intermediate layer. 8. The method of claim 7, wherein said radiation is selected from the group consisting of electron projection radiation, EUV radiation and soft x-ray radiation. 8. The method of claim 7, wherein the substrate is baked between steps (C) and (D).