Reagent for enhancing generation of chemical species

Abstract

A reagent that enhances acid generation of a photoacid generator and composition containing such reagent is disclosed.

Claims

1. A composition, comprising: a reagent; a first compound able to react with a chemical species to cause a deprotection reaction of the first compound; and a precursor, wherein the reagent is selected from the group consisting of a first reagent, a second reagent, and a third reagent, the first reagent being represented by one of formula (I), ##STR00008## wherein R.sup.1 is a hydrogen atom; R.sup.2 is a phenyl group, an alkyl carbonyl group, an aryl carbonyl group, an alkyl group, an alkenyl group, an aralkyl group, an alkynyl group, an alkyl group containing a cyclic or poly cyclic moiety, or a substituent containing at least one atom other than carbon atom and hydrogen atom; and R.sup.3 is a hydrogen atom, a phenyl group, an alkyl carbonyl group, an aryl carbonyl group, an alkyl group, an alkenyl group, an aralkyl group, an alkynyl group, an alkyl group containing a cyclic or poly cyclic moiety, or a substituent containing at least one atom other than carbon atom and hydrogen atom, the second reagent being represented by one of formula (II), ##STR00009## wherein R.sup.1 is a hydrogen atom; R.sup.2 is a phenyl group, an alkyl carbonyl group, an aryl carbonyl group, an alkyl group, an alkenyl group, an aralkyl group, an alkynyl group, an alkyl group containing a cyclic or poly cyclic moiety, or a substituent containing at least one atom other than carbon atom and hydrogen atom; R.sup.3 is a hydrogen atom, a phenyl group, an alkyl carbonyl group, an aryl carbonyl group, an alkyl group, an alkenyl group, an aralkyl group, an alkynyl group, an alkyl group containing a cyclic or poly cyclic moiety, or a substituent containing at least one atom other than carbon atom and hydrogen atom; and R.sup.4 is a protective group for a hydroxyl group or a group containing a carbon atom; and the third reagent includes a hydroxyl group and a first cyclic moiety that contains a carbon atom bonded to the hydroxyl group and a hydrogen atom; wherein: an intermediate is generated from the reagent by a feed energy; the intermediate enhances a generation of the chemical species from a precursor; a product resulting from the intermediate has a conjugation length longer than a conjugation length of the reagent; wherein the feed energy is carried out by a first irradiation of the reagent or an acceptor receiving the energy with at least one of a light, the wavelength of which is shorter than or equal to 15 nm and an electron beam; and wherein the generation of the chemical species from the precursor is improved by a second irradiation with a light, the wavelength of which is longer than or equal to 300 nm.

2. The composition according to claim 1, wherein a reaction of the chemical species with a first compound or the precursor regenerates the chemical species.

3. The composition according to claim 1, wherein the intermediate has a reducing character.

4. The composition according to claim 1, wherein the intermediate is a radical.

5. The composition according to claim 1, wherein the intermediate discharges at least one of a hydrogen atom and hydrogen ion that have reducing characters.

6. The composition according to claim 1, wherein the intermediate is a ketyl radical.

7. The composition according to claim 1, wherein the chemical species is acid.

8. The composition according to claim 1, wherein R.sup.2 is connected to R.sup.3 through at least one bond.

9. The composition according to claim 1, wherein at least one of R.sup.2 and R.sup.3 is an aromatic group.

10. The composition according to claim 1, wherein the product is formed by oxidation of the intermediate.

11. The composition according to claim 1, wherein: the reagent further includes a second cyclic moiety; and the first cyclic moiety contains at least two atoms which are also contained in the second cyclic moiety.

12. The composition according to claim 1, wherein R.sup.4 is one of an ester group, alkyl group and tetrahydropyranyl group.

13. A method for manufacturing a device, the method comprising: applying a solution of the composition according to claim 1 to a substrate such that a coating film including the composition is formed on the substrate; a first irradiating the coating film with at least one of a first electromagnetic ray and a first particle ray such that a first portion of the coating film is irradiated with the at least one of the electromagnetic ray and the particle ray while a second portion of the coating film is not irradiated with the at least one of the electromagnetic ray and the particle ray; a second irradiating the coating film with at least one of a second electromagnetic ray and a second particle ray; removing the first portion; and etching the substrate such that a third portion of the substrate on which the first portion has been present is etched.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings, which illustrate what is currently considered to be the best mode for carrying out the disclosure:

(2) The FIGURE shows fabrication processes of a device such as an integrated circuit (IC) using photoresist including an acid-generation enhancer.

DETAILED DESCRIPTION

Experimental Procedures

Synthesis of 2,4-dimethoxy-4-methoxybenzophenone

(3) 2.00 g of 2,4-dihydroxy-4-hydroxybenzophenone, 1.95 g of dimethyl sulfate and 2.14 g of potassium carbonate are dissolved in 16.0 g of acetone. The mixture is stirred at reflux temperature for 8 hours. Since then, the mixture is cooled to 25 degrees Celsius and further stirred after addition of 80.0 g of water, then extracted with 20.0 g ethyl acetate and the organic phase is washed with water. Thereafter, ethyl acetate is distilled away, and the resultant is purified by silica gel column chromatography (ethyl acetate:hexane=3:97). Thereby, 1.43 g of 2, 4-dimethoxy-4-methoxybenzophenone is obtained.

Synthesis of (2,4-dimethoxyphenyl)-(4-methoxyphenyl)-methanol

Example 1

(4) 1.0 g of 2,4-dimethoxy-4-methoxybenzophenone and 0.01 g of potassium hydroxide are dissolved in 12.0 g of methanol. 0.42 g of sodium boron hydride is added to the methanol solution. The mixture is stirred at reflux temperature for 3 hours. Since then, the mixture is added to the 80 g of water, then extracted with 20.0 g ethyl acetate and the organic phase is washed with water. Thereafter, ethyl acetate is distilled away. Thereby, 0.90 g of (2,4-dimethoxyphenyl)-(4-methoxyphenyl)-methanol is obtained.

(5) ##STR00004##

(6) A solution containing 5.0 g of -methacryloyloxy--butylolactone, 6.03 g of 2-methyladamantane-2-methacrylate, and 4.34 g of 3-hydroxyadamantane-1-methacrylate, 0.51 g of dimethyl-2,2-azobis(2-methylpropionate), and 26.1 g of tetrahydrofuran is prepared. The prepared solution is added for 4 hours to 20.0 g of tetrahydrofuran placed in flask with stirring and boiling. After the addition of the prepared solution, the mixture is heated to reflux for 2 hours and cooled to room temperature. Addition of the mixture by drops to a mixed liquid containing 160 g of hexane and 18 g of tetrahydrofuran with vigorous stirring precipitates the copolymer. The copolymer is isolated by filtration. Purification of the copolymer is carried out by vacuum drying following two washings by 70 g of hexane, and thereby 8.5 g of white powder of the copolymer is obtained.

(7) ##STR00005##

Preparation of Samples for Evaluation (The Evaluation Sample)

(8) The Evaluation Samples are prepared by dissolving 23.5 mg of (2,4-dimethoxyphenyl)-(4-methoxyphenyl)-methanol, 600 mg of resin A and 24.9 mg of diphenyliodonium nonafluorobutanesulfonate as a photoacid generator (PAG) in 8000 mg of cyclohexanone.

(9) Evaluation of Sensitivity

(10) Before applying each of the Evaluation Samples to an Si wafer, hexamethyldisilazane (HMDS, Tokyo Chemical Industry) is spin-coated at 2000 rpm for 20 seconds on the surface of the Si wafer and baked at 110 degrees Celsius for 1 minute. Then, each of the Evaluation Samples is spin-coated on the surface Si wafers that have been treated with HMDS at 2000 rpm for 20 seconds to form a coating film. The prebake of the coating film is performed at 110 degrees Celsius for 60 seconds. Then, the coating film of the Evaluation Sample is exposed to an extreme ultraviolet (EUV) output from an EUV light source. After the EUV light exposure, an irradiation of the coating film with a UV light is carried out at an ambient condition. After the UV light exposure, a post-exposure-bake (PEB) is carried out at 100 degrees Celsius for 60 seconds. The coating film is developed with NMD-3 (tetra-methyl ammonium hydroxide 2.38%, Tokyo Ohka Kogyo) for 60 seconds at 25 degrees Celsius and rinsed with deionized water for 10 seconds. The thickness of the coating film measured using film thickness measurement tool is approximately 150 nm.

(11) A sensitivity (E.sub.0 sensitivity) is evaluated by measuring the dose size to form a pattern constituted by 2 m lines where the thickness of the coating film is not zero and 2 m spaces where the thickness of the coating film is zero using 30 keV EBL system JSM-6500F (JEOL, beam current: 12.5 pA, <1E-4 Pa) with Beam Draw (Tokyo Technology) and the UV exposures using FL-6BL (bright line is mainly from 320 nm to 380 nm, Toshiba).

(12) Even if the UV exposure is carried out without a mask, 2 m spaces are formed in the parts of the coating film that have been exposed to the EUV light. This indicates that a product functioning as a photosensitizer for the UV light is generated in the parts exposed to the EUV light.

(13) Table 1 shows the dose sizes corresponding to E.sub.0 sensitivities measured for Evaluation Samples 1 to 4. Table 1 indicates that the doses of the UV exposure for E.sub.0 sensitivity decreases with increase of the doses of the EUV light exposure.

(14) TABLE-US-00001 TABLE 1 The doses for E.sub.0 light by an EUV light and UV exposure for the Evaluation Samples Total dose for E.sub.0 EUV dose UV dose [C/cm.sup.2] [mJ/cm.sup.2] Run 1 20.0 0 Run 2 13.8 560 Run 3 8.8 1100 Run 4 3.8 3350

(15) Each of Examples 2, 3, 4, and 5 are also preferably used as AGE instead of (2,4-dimethoxyphenyl)-(4-methoxyphenyl)-methanol. Each of the Examples is converted into a corresponding ketone that can function as a photosensitizer after an EUV light or electron beam exposure.

(16) ##STR00006##

(17) Examples 1-5 are also protected by a protective group such as tetrahydropyranyl and ester.

Synthesis of bis-(4-methoxyphenyl) methanol

(18) 2.0 g of 4,4-dimethoxybenzohenone and 0.02 g of potassium hydroxide are dissolved in 16.0 g of methanol. 0.94 g of sodium boronhydride is added to the methanol. The mixture is stirred at reflux temperature for 3 hours. Since then, the mixture is added to the 80 g of water, then extracted with 20.0 g of ethyl acetate and the organic phase is washed with water. Thereafter, ethyl acetate is distilled away. Thereby, 1.79 g of bis-(4-methoxyphenyl)methanol is obtained.

Synthesis of 2-[Bis-(4-methoxy-phenyl)-methoxy]-tetrahydro-pyran

Example 6

(19) ##STR00007##

(20) 2.75 g of 2H-dihydropyran and 0.74 g of pyridinium p-toluenesulfonate are dissolved in 30.0 g of methylene chloride. 2.0 g of bis-(4-methoxyphenyl)methanol dissolved by 8.0 g of methylene chloride is added dropwise to the mixture containing 2H-dihydropyran and pyridinium p-toluenesulfonate over 30 minutes. After that, the mixture is stirred at 25 degrees Celsius for 3 hours. Since then, the mixture is further stirred after addition of 3% aqueous solution of sodium carbonate, then extracted with 20.0 g of ethyl acetate and the organic phase is washed with water. Thereafter, ethyl acetate is distilled away. Thereby, 1.99 g of 2-[Bis-(4-methoxy-phenyl)-methoxy]-tetrahydro-pyran is obtained.

Preparation of Evaluation Samples 5 and 6

(21) Evaluation Sample 5 is prepared by dissolving 300 mg of resin A, 36.7 mg of diphenyliodonium nonafluorobutanesulfonate as a photoacid generator (PAG), and 13.7 mg of coumarin 6 as an indicator in 2000 mg of cyclohexanone.

(22) Evaluation Sample 6 is prepared by dissolving 14.1 mg of 2-[Bis-(4-methoxy-phenyl)-methoxy]-tetrahydro-pyran, 300 mg of resin A, 36.7 mg of 4,4-di-(t-butyphenyl)iodonium nonafluorobutanesulfonate as a PAG, and 13.7 mg of coumarin 6 as an indicator in 2000 mg of cyclohexanone.

(23) Evaluation of Efficiency of Acid Generation

(24) Films are formed on 4-inch quartz wafers by spin-coating of Evaluation Samples 5 and 6. Each of the films is irradiated with EUV light, of which volumes are 0, 10, 20, 30, and 40 C/cm.sup.2 output by an EUV light lithography apparatus. Subsequent to the EUV light irradiations, the efficiencies for the films are obtained by plotting absorbances at 534 nm and each of the films are assigned to quantities of protonated coumarin 6 generated by the respective volumes of EUV.

(25) Table 2 shows the relative acid-generation efficiencies for the Evaluation Samples 5 and 6. In Table 2, the acid-generation efficiency for the Evaluation Sample 5 is used as a benchmark. The results shown in Table 2 indicate that the acid-generation efficiency is improved by the reduction of the photoacid generator by ketyl radical formed from 2-[Bis-(4-methoxy-phenyl)-methoxy]-tetrahydro-pyran. This indicates that the tetrahydropyranyl group of 2-[Bis-(4-methoxy-phenyl)-methoxy]-tetrahydro-pyran is cleaved by generated acid by exposure of an EUV light and bis-(4-methoxyphenyl)methanol is generated.

(26) TABLE-US-00002 TABLE 2 The relative acid-generation efficiencies for the Evaluation Samples 5 and 6 Relative acid-generation efficiency Evaluation Sample 5 1.0 Evaluation Sample 6 1.1

(27) As understood from the results, a reactive intermediate having reducing character that is protected by an acid-dissociable group is also considered to enhance the efficiency of acid generation.

(28) A reaction of Example 6 with acid results in a corresponding alcohol. The corresponding alcohol is oxidized to a corresponding ketone, which can act as a photosensitizer. Therefore, if an irradiation with a light of which wavelength is longer than 220 nm is carried out after exposure to a solution containing Example 6 and a PAG to EUV light or electron beam, the efficiency of acid generation is further enhanced.

(29) A photoresist including Example 6 as AGE obtained by the processes by the above procedures can be applied to fabrication processes of a device, such as an integrated circuit (IC).

(30) The FIGURE shows fabrication processes of a device such as an integrated circuit (IC) using a photoresist including the acid generation enhancer (AGE) obtained by the processes by the above procedures.

(31) A silicon wafer is provided. The surface of a silicon wafer is oxidized by heating the silicon wafer in the presence of oxygen gas.

(32) A solution of a chemically amplified composition (CAR) including an AGE, resin A, and a PAG is applied to the surface of an Si wafer by spin coating to form a coating film. The coating film is prebaked.

(33) An irradiation of the coating film with an EUV light through a mask is carried out after prebake of the Si wafer. The deprotection reaction of resin A is induced by acid generated by photoreaction of the photoacid generator and assistance by AGE.

(34) An electron beam can be used instead of the EUV light.

(35) After the EUV irradiation of the coating film, an irradiation of the coating film with a light of which wavelength is equal to or longer than 300 nm is carried out without any mask.

(36) Development of the coating film that has been irradiated with the EUV light and the light of which wavelength is equal to or longer than 300 nm is performed after the prebake.

(37) The coating film and the silicon wafer are exposed to plasma. After that, the remaining film is removed.

(38) An electronic device such as an integrated circuit is fabricated utilizing the processes shown in the FIGURE. The deterioration of the device due to the irradiation with a light is suppressed, compared to existing photoresists since times for irradiation of the coating film is shortened.

(39) AGEs can be bound to a polymer chain. For example, at least each of a mother moiety of Examples 1-6 can be a polymer chain through an ether group or an ester group.