Reagent for enhancing generation of chemical species

Abstract

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

Claims

1. A composition comprising: a photoacid generator having iodonium salt or sulfonium salt; a compound having a protecting group capable of being deprotected by the acid; and a reagent with a first structure forming a carbon radical, wherein a first cutoff wavelength in a first absorption spectrum of the reagent is shorter than a second cutoff wavelength of a second absorption spectrum of the carbon radical, and wherein the reagent is represented by Formula (I) or Formula (II): ##STR00010## wherein: R.sup.2 is a phenyl group; R.sup.3 is an alkyl group or a phenyl group; at least one phenyl group of R.sup.2 and R.sup.3 has at least one electron-donating group selected from the group consisting of an alkoxy group, a hydroxy group, an aryloxy group, an alkylthio group, an arylthio group, and an amino group having at least one of a hydrogen atom, an alkyl group, and an aryl group on a nitrogen atom of the amino group; each of R.sup.4 and R.sup.5 is independently selected from the group consisting of a hydrogen atom, an alkyl group, and a phenyl group; and R.sup.2 may be bonded to R.sup.3 directly or indirectly through at least one atom selected from the group consisting of a carbon atom, an oxygen atom, a nitrogen atom, and a sulfur atom; ##STR00011## wherein: R.sup.8 is a phenyl group; R.sup.9 is an alkyl group or a phenyl group; at least one of the phenyl groups of R.sup.8 and R.sup.9 has at least one electron-donating group selected from the group consisting of an alkoxy group, a hydroxy group, an aryloxy group, an alkylthio group, an arylthio group, and an amino group having at least one of a hydrogen atom, an alkyl group, and an aryl group on a nitrogen atom of the amino group; wherein: one of R.sup.9 and the electron-donating group may be bonded with a (meth)acryloyloxy alkyl group; and R.sup.8 may be bonded to R.sup.9 directly or indirectly through at least one atom selected from the group consisting of a carbon atom, an oxygen atom, a nitrogen atom and a sulfur atom, wherein the reagent includes at least one selected from the group consisting of ##STR00012##

2. The composition of claim 1, wherein the compound is a copolymer with the first structure as a unit.

3. A method of manufacturing a device, comprising: preparing the composition of claim 1; forming a film by coating the composition on a wafer; exposing a first portion of the film to at least one of a first electromagnetic ray and a first particle ray, while a second portion of the film is not exposed to the at least one of the first electromagnetic ray and the first particle ray; and exposing at least a portion of the first portion of the film to at least one of a second electromagnetic ray and a second particle ray.

4. The method of claim 3, further comprising: developing the film to remove the first portion of the film and expose at least a portion of the wafer.

5. The method of claim 4, further comprising: etching the exposed portions of the wafer.

6. The method of claim 3, wherein the first electromagnetic ray and the first particle ray are an extreme ultraviolet (EUV) light and an electron beam (EB), respectively.

7. A composition comprising: a reagent represented by Formula (I) or Formula (II): ##STR00013## wherein: R.sup.2 is a phenyl group; R.sup.3 is an alkyl group or a phenyl group; each of R.sup.4 and R.sup.5 is independently selected from the group consisting of a hydrogen atom, an alkyl group, and a phenyl group; at least one phenyl group of R.sup.2 and R.sup.3 has at least one electron-donating group selected from the group consisting of an alkoxy group, a hydroxy group, an aryloxy group, an alkylthio group, an arylthio group, and an amino group having at least one of a hydrogen atom, an alkyl group, and an aryl group on a nitrogen atom of the amino group; and one of R.sup.3-R.sup.5 and the electron-donating group may be bonded with a (meth)acryloyloxy alkyl group; ##STR00014## wherein: R.sup.8 is a phenyl group; R.sup.9 is an alkyl group or a phenyl group; at least one phenyl group of R.sup.8 and R.sup.9 has at least one electron-donating group selected from the group consisting of an alkoxy group, a hydroxy group, an aryloxy group, an alkylthio group, an arylthio group, and an amino group having at least one of a hydrogen atom, an alkyl group, and an aryl group on a nitrogen atom of the amino group; one of R.sup.9 and the electron-donating group may be bonded with a (meth)acryloyloxy alkyl group; and a resin, wherein the reagent includes at least one selected from the group consisting of ##STR00015##

8. A reagent represented by Formula (I) or Formula (II): ##STR00016## wherein: R.sup.2 is a phenyl group; R.sup.3 is an alkyl group or a phenyl group; each of R.sup.4 and R.sup.5 is independently selected from the group consisting of a hydrogen atom, an alkyl group, and a phenyl group; at least one phenyl group of R.sup.2 and R.sup.3 is an aryl group having at least one electron-donating group selected from the group consisting of an alkoxy group, a hydroxy group, an aryloxy group, an alkylthio group, an arylthio group, and an amino group having at least one of a hydrogen atom, an alkyl group, and an aryl group on a nitrogen atom of the amino group; one of R.sup.3-R.sup.5 and the electron-donating group may be bonded with a (meth)acryloyloxy alkyl group; and R.sup.2 may be bonded to R.sup.3 directly or indirectly through at least one atom selected from the group consisting of a carbon atom, an oxygen atom, a nitrogen atom and a sulfur atom; ##STR00017## wherein: R.sup.8 is a phenyl group; R.sup.9 is an alkyl group or a phenyl group; at least one phenyl group of R.sup.8 and R.sup.9 has at least one electron-donating group selected from the group consisting of an alkoxy group, a hydroxy group, an aryloxy group, an alkylthio group, an arylthio group, and an amino group having at least one of a hydrogen atom, an alkyl group, and an aryl group on a nitrogen atom of the amino group; one of R.sup.9 and the electron-donating group may be bonded with a (meth)acryloyloxy alkyl group; and R.sup.8 may be bonded to R.sup.9 directly or indirectly through at least one atom selected from the group consisting of a carbon atom, an oxygen atom, a nitrogen atom and a sulfur atom, wherein the reagent includes at least one selected from the group consisting of ##STR00018##

9. A method of manufacturing a device, the method comprising: preparing the composition of claim 7; forming a film by coating the composition onto a wafer; exposing a first portion of the film to at least one of a first electromagnetic ray and a first particle ray, while a second portion of the film is not exposed to the at least one of the first electromagnetic ray and the first particle ray; and exposing at least a part of the second portion to at least one of a second electromagnetic ray and a second particle ray.

10. A composition comprising: a photoacid generator; and a compound including a resin having a structure wherein at least one reagent of claim 8 is bonded to a polymer chain of the resin via a linking group.

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 invention:

(2) FIG. 1 shows a typical reaction scheme of a composition containing a reagent relating to an aspect hereof.

(3) FIG. 2 shows a typical reaction scheme of a composition a reagent relating to another aspect hereof.

(4) FIG. 3 shows fabrication processes of a device such as integrated circuit (IC) using a CAR containing a reagent relating to an aspect hereof.

DETAILED DESCRIPTION

(5) The invention is further explained with the aid of the following illustrative examples.

Experimental Procedures

Synthesis of 2-isopropenyl-1,3,5-trimethoxy-benzene

(6) 2.00 g of 2,4,6-trimethoxyacetophenone and 3.74 g of methyltriphenyphosphonium bromide are added to 20 g of tetrahydrofuran. 2.13 g of potassium tert-butoxide is added to the tetrahydrofuran mixture containing 2,4,6-trimethoxyacetophenone and methyltriphenyphosphonium bromide. The mixture is stirred at 60 degrees Celsius for 2 hours and the mixture is filtrated. Afterwards, the tetrahydrofuran is distilled away and 20 g of cyclohexane is added to the residue. The cyclohexane mixture is stirred for 10 minutes and a deposit is filtrated and the filtrate is collected. Thereafter, cyclohexane is distilled away, and the resultant is purified by silica gel column chromatography (ethyl acetate:hexane=10:90). Thereby 1.62 g of 2-isopropenyl-1,3,5-trimethoxy-benzene is obtained.

Synthesis of 2-isopropyl-1,3,5-trimethoxy-benzene (Reagent 1)

(7) 1.50 g of 2-isopropenyl-1,3,5-trimethoxy-benzene and 0.08 g of 5% palladium carbon are added to 15.0 g of ethyl acetate. The mixture is stirred at 25 Celsius degrees for 3 hours in 1 atm hydrogen atmosphere. Afterwards, the mixture is filtrated and the filtrate is collected. Thereafter, ethyl acetate is distilled away, and the resultant is purified by silica gel column chromatography (ethyl acetate:hexane=5:95). Thereby 2.20 g of 2-isopropyl-1,3,5-trimethoxy-benzene is obtained.

(8) ##STR00005##

Synthesis of 9-benzylidene-9H-thioxanthene

(9) 4.00 g of thioxanthone and 8.06 g of benzyltriphenyphosphonium chloride are added to 40.0 g of tetrahydrofuran. 3.17 g of potassium tert-butoxide is added to the tetrahydrofuran mixture containing thioxanthone and benzyltriphenyphosphonium chloride. The mixture is stirred at 25 degrees Celsius for 140 hours and the mixture is filtrated. Afterwards, the tetrahydrofuran is distilled away and 40 g of cyclohexane is added to the residue. The cyclohexane mixture is stirred for 10 minutes and a deposit is filtrated and the filtrate is collected. Thereafter, cyclohexane is distilled away, and the resultant is purified by silica gel column chromatography (ethyl acetate:hexane=1:99). Thereby 2.91 g of 9-benzylidene-9H-thioxanthene is obtained.

Synthesis of 9-benzyl-9H-thioxanthene (Reagent 2)

(10) 2.80 g of 9-benzylidene-9H-thioxanthene and 0.14 g of 5% palladium carbon are added to 28.0 g of ethyl acetate. The mixture is stirred at 40 Celsius degrees for 12 hours in 1 atm hydrogen atmosphere. Afterwards, the mixture is filtrated and the filtrate is collected. Thereafter, ethyl acetate is distilled away, and the resultant is purified by silica gel column chromatography (ethyl acetate:hexane=1:99). Thereby 2.62 g of 9-benzyl-9H-thioxanthene is obtained.

(11) ##STR00006##

Synthesis of 3-(2,4,6-trimethoxy-phenyl)-but-2-en-1-ol

(12) 4.00 g of 2,4,6-trimethoxyacetophenone and 8.10 g of (2-hydroxyethyl)triphenyphosphonium bromide are added to 40 g of tetrahydrofuran. 3.80 g of 40% aqueous sodium hydroxide is added to the tetrahydrofuran mixture containing 2,4,6-trimethoxyaetophenone and (2-hydroxyethyl)triphenyphosphonium bromide. The mixture is stirred at 60 degrees Celsius for 4 hours and the mixture is filtrated. Afterwards, the tetrahydrofuran is distilled away and 40 g of cyclohexane is added to the residue. The cyclohexane mixture is stirred for 10 minutes and a deposit is filtrated and the filtrate is collected. Thereafter, cyclohexane is distilled away, and the resultant is purified by silica gel column chromatography (ethyl acetate:hexane=10:90). Thereby 3.49 g of 3-(2,4,6-trimethoxy-phenyl)-but-2-en-1-ol is obtained.

Synthesis of 3-(2,4,6-trimethoxy-phenyl)-butan-1-ol

(13) 3.30 g of 3-(2,4,6-trimethoxy-phenyl)-but-2-en-1-ol and 0.17 g of 5% palladium carbon are added to 33.0 g of ethyl acetate. The mixture is stirred at 25 Celsius degrees for 4 hours in 1 atm hydrogen atmosphere. Afterwards, the mixture is filtrated and the filtrate is collected. Thereafter, ethyl acetate is distilled away, and the resultant is purified by silica gel column chromatography (ethyl acetate:hexane=10:90). Thereby 3.10 g of 3-(2,4,6-trimethoxy-phenyl)-butan-1-ol is obtained.

Synthesis of 2-methyl-acrylic acid 3-(2,4,6-trimethoxy-phenyl)-butyl ester (Reagent 3)

(14) 3.00 g of 3-(2,4,6-trimethoxy-phenyl)-butan-1-ol and 2.12 g of methacrylic anhydride are dissolved in 21 g of tetrahydrofuran. 1.52 g of triethylamine dissolved in 4.55 g of tetrahydrofuran is added dropwise to the tetrahydrofuran solution containing 3-(2,4,6-Trimethoxy-phenyl)-butan-1-ol over 10 minutes. After that the mixture is stirred at 25 degrees Celsius for 3 hours. Since then, the mixture is further stirred after addition of water. Then extracted with 60 g ethyl acetate and the organic phase is washed with water. Thereafter, ethyl acetate is distilled away, and the residue is purified by silica gel column chromatography (ethyl acetate:hexane=1:9). Thereby 3.12 g of 2-methyl-acrylic acid 3-(2,4,6-trimethoxy-phenyl)-butyl ester is obtained.

(15) ##STR00007##

(16) 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 dropwise over 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 vigorously stirring precipitates the copolymer. The copolymer is isolated by filtration. Purification of the copolymer is carried out by vacuum drying following twice washings by 70 g of hexane, and thereby 8.5 g of white powder of the copolymer (Resin A) is obtained.

(17) ##STR00008##

(18) A solution containing 1.20 g of 2-methyl-acrylic acid 3-(2,4,6-trimethoxy-phenyl)-butyl ester, 9.27 g of -methacryloyloxy--butylolactone, 9.12 g of 2-methyladamantane-2-methacrylate, 7.67 g of 3-hydroxyadamantane-1-methacrylate, 0.30 g of butyl mercaptane, 1.49 g of dimethyl-2,2-azobis(2-methylpropionate) and 22.8 g of tetrahydrofuran is prepared. The prepared solution is added dropwise over 4 hours to 8.0 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 287 g of hexane and 32 g of tetrahydrofuran with vigorously stirring precipitates the copolymer. The copolymer is isolated by filtration. Purification of the copolymer is carried out by vacuum drying following twice washings by 100 g of hexane, and thereby 19.9 g of white powder of the copolymer (Resin B) is obtained.

(19) ##STR00009##

(20) Preparation of Samples for Evaluation (the Evaluation Samples)

(21) Each of Evaluation Samples 1-8 contains 15.0 mg of coumarin 6 as an indicator for acid generation and 2000 mg of cyclohexanone. Each of Evaluation Samples 1-3 and 7 contains 0.043 mmol of diphenyliodonium nonafluorobutanesulfonate (DPI-PFBS) as a photoacid generator (PAG) while each of Evaluation Samples 4-6 and 8 contains 5-phenyl-dibenzothiophenium nonafluorobutanesulfonate (PBpS-PFBS) as a PAG. Each of Evaluation Samples 1-6 contains 300 mg of Resins A while Evaluation Samples 7 and 8 contain 300 mg of Resin B. Evaluation Samples 2 and 5 contain 0.087 mmol of Reagent 1 while Evaluation Samples 3 and 6 contain 0.087 mmol of Reagent 2, Table 1 shows the summary of constituents of Evaluation Samples 1-8.

(22) TABLE-US-00001 TABLE 1 Samples for evaluation for efficiencies of patterning Resin PAG Additive Solvent Evaluation Sample 1 Resin A DPI-PFBS Cyclohexanone Evaluation Sample 2 Reagent 1 Evaluation Sample 3 Reagent 2 Evaluation Sample 4 PBpS-PFBS Evaluation Sample 5 Reagent 1 Evaluation Sample 6 Reagent 2 Evaluation Sample 7 Resin B DPI-PFBS Evaluation Sample 8 PBpS-PFBS

(23) Evaluation of Efficiency of Acid Generation

(24) Films are formed on 4-inch quartz wafers by spin-coating of Evaluation Samples. Two runs are carried out for each of Evaluation Samples 1-8. For one run of the two runs, an exposure of a film to a series of electron beams of which volumes are 0, 10, 20, 30, and 40 C/cm.sup.2 output from an electron beam (EB) lithography apparatus is carried out. For the other run of the two runs, such EB exposure and an exposure to a UV light (3 of Nd: YAG laser) with a delay of a predetermined amount of time (5 s) from the EB exposure are carried out.

(25) Subsequent to the EB exposure (if any, the UV exposure), the efficiency of acid generation for the film is obtained by plotting absorbances at 534 nm which are indicators of quantities of protonated coumarin 6 generated by the EB exposures (if any, the UV exposure) with the respective volumes.

(26) Table 2 shows the relative acid-generation efficiencies for Evaluation Samples 1-8. For the runs 2, 4, 6, 8, 10, 12, 14, 16 and 18, in addition to an EB exposure, an UV exposure (1000 mJ/cm.sup.2) is carried out with a delay of 5 s from the EB exposure. In Table 2, the acid-generation efficiency for Run 1 is used as a benchmark.

(27) As the runs 3-6 and 9-16 indicates, additions of Reagent 1, Reagent 2 and Resin B containing B-1 moiety improves the acid generation efficiencies. This indicates that Reagent 1, Reagent 2 and B-1 moiety of Resin B act as acid generation enhancers (AGEs).

(28) The PAGs are considered to be reduced by radicals each of which has unpaired electron present in a carbon atom bonded to an aryl group generated from Reagent 1, Reagent 2 and B-1 moiety of Resin B by the EB exposures.

(29) From comparisons of runs 3, 4, 5, 6, 13 and 14 with runs 9, 10, 11, 12, 15 and 16, respectively, acid generation efficiencies for DPI-PFBS is found to be greater than those for PBpS-PFBS. This is thought to be due to the higher electron-accepting ability of DPI-PFBS compared to PBpS-PFBS.

(30) For runs 4, 6, 10, 12, 14 and 16 higher acid generation efficiencies are observed compared runs 3, 5, 9, 11, 13 and 15, respectively. This indicates that excitation of such radicals improve additionally acid generation efficiencies.

(31) Reagent 1 is considered to have a level of a highest occupied molecular orbital (HOMO) similar to that of B-1 moiety of Resin B. However, acid generation efficiencies of Evaluation Samples 7 and 8 containing Resin B are higher than those of Evaluation Samples containing Reagent 1.

(32) This implies that the homogeneous dispersion of AGE (such as B-1) moieties into the polymer matrix improves acid generation efficiency.

(33) TABLE-US-00002 TABLE 2 The relative acid-generation efficiencies for the Evaluation Samples 1-8 Evaluation Relative Run Sample Efficiency 1 1 1.00 2 1.00 3 2 1.20 4 1.30 5 3 1.10 6 1.30 7 4 0.90 8 0.90 9 5 0.98 10 1.10 11 6 0.95 12 1.10 13 7 1.26 14 1.38 15 8 1.00 16 1.14

(34) FIG. 1 shows a typical reaction scheme of a composition containing a Reagent 1 and DPI-PFBS as a PAG. An exposure of the composition to an EUV or EB yields a radical such as phenyl radical generated by decomposition of the PAG. A hydrogen atom bonded to a carbon atom bonded to an aromatic group of Reagent 1 is abstracted by phenyl radical to form a radical BR-1 of which unpaired electron is present in the carbon bonded to the aromatic group. In other words, a benzyl-type radical is generated.

(35) The radical BR-1 donates an electron the PAG. Such electron-donation to the PAG, which yields acid, is additionally enhanced by an excitation of the radical BR-1. Through such electron-donation to the PAG, the radical BR-1 is converted into TME which has one carbon-carbon multiple bond bonded to the aromatic group. The conversion to TME from BR-1 is accompanied with an elimination of a group such as hydrogen atom. Acid generated from the PAG deprotects resin contained in the composition.

(36) FIG. 2 shows a typical reaction scheme of a composition containing a Reagent 2 and DPI-PFBS as a PAG. An exposure of the composition to an EUV or EB yields a radical such as phenyl radical generated by decomposition of the PAG. A hydrogen atom bonded to a carbon atom bonded to two aromatic groups of Reagent 2 is abstracted by phenyl radical to form a radical DR-1 of which unpaired electron is present in the carbon bonded to the two aromatic groups. In other words, a benzyl-type radical is generated.

(37) The radical DR-1 donates an electron the PAG. Such electron-donation to the PAG, which yields acid, is additionally enhanced by an excitation of the radical DR-1. Through such electron-donation to the PAG, the radical DR-1 is converted into BTX which has one carbon-carbon multiple bond bonded to the two aromatic groups. The conversion to BTX from Dr-1 is accompanied with an elimination of a group such as hydrogen atom. Acid generated from the PAG deprotects resin contained in the composition.

(38) FIG. 3 shows fabrication processes of a device such as integrated circuit (IC) by using a chemically-amplified resist (CAR) containing Reagent 1.

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

(40) A solution of the CAR containing Reagent 2 is applied to the surface of an Si wafer by spin coating to form a coating film. The coating film is prebaked.

(41) Then, an irradiation of the coating film with a EUV light through a mask and an irradiation of a part including an irradiated portion with the EUV light of the coating film with a 3 of Nd: YAG Laser is carried out with 5-10 s of a delay from the EUV irradiation. In other words, a transient excitation of the coating film is carried out by using the 3 of Nd: YAG Laser.

(42) After the irradiation of the coating film with the EUV light and the transient excitation are carried out, development of the coating film which has been irradiated with the EUV light and the 3 of Nd: YAG Laser is performed.

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

(44) An electronic device such as integrated circuit is fabricated utilizing the processes shown in FIG. 3. The deterioration of the device due to the irradiation with a light is suppressed compared to existing photoresists since times for the irradiation of the coating film is shortened by using the transient excitation.