JP5317611B2 - Photosensitive composition and pattern forming method using the same - Google Patents

Description

  The present invention relates to a photosensitive composition, and a pattern forming method and an image forming method using the same.

  In the manufacture of semiconductor integrated circuits, fine processing by lithography using high-energy chemical radiation such as ultraviolet rays or electron beams is performed. With the high integration of LSI and the like, recently, fine patterning characteristics of 100 nm or less are required.

  Resist is required to have characteristics such as a uniform film and high dry etching resistance, and resists containing aromatic compounds have been widely used. In a polymer compound, the molecular size is beginning to affect edge roughness and the like, and it is becoming difficult to increase the resolution with a resist based on a polymer compound (see, for example, Non-Patent Document 1). Therefore, attempts have been made to use, as a resist matrix, a low molecular weight compound that exhibits amorphous properties that forms a uniform film called a molecular resist. Since low-molecular compounds have higher crystallinity than polymers, several compounds are being searched for.

  Currently, a chemically amplified resist containing a photoacid generator is mainly used. Since such a resist includes an acid diffusion mechanism, a sufficient contrast can be obtained by irradiation with a small amount of actinic radiation, which is advantageous in terms of high throughput. However, problems arise when forming ultrafine patterns. For example, there is a limit in resolution due to the diffusion of acid from the exposed area to the unexposed area, and the roughness may also become significant.

Therefore, in order to obtain an ultrafine pattern with high resolution and low roughness, an EB resist using a cyclic phenol derivative or fullerene derivative such as calixarene, which is non-chemically amplified and has a low molecular weight and high heat resistance, has been reported. (For example, see Non-Patent Document 2 and Patent Document 1). Calixarene and fullerene derivatives require a dose of several mC / cm ² to several C / cm ² and are relatively low in sensitivity. Moreover, since it is an organic solvent that is used as a developing solution, it is contrary to the recent trend to consider the environment.
J. Photopolym. Sci. Technol., 10, 629 (1997) J. Photopolym. Sci. Technol., 10, 641 (1997) Japanese Patent Laid-Open No. 11-258996

  An object of the present invention is to provide a photosensitive composition that reacts with high sensitivity to irradiation with ultraviolet rays or ionizing radiation, has high resolution and improved edge roughness, and is capable of alkali development.

The photosensitive compound concerning 1 aspect of this invention is characterized by including the structure represented by the following general formula (I), and showing amorphous property.

(In the general formula (I), R ¹ and R ² may be the same or different, and are a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and a substituted or non-substituted group having 1 to 10 carbon atoms. (Selected from substituted aromatic groups. M1 and m2 are integers of 1 to 4. n is an integer of 0 or more and 2 or less.)
The photosensitive compound according to another embodiment of the present invention includes a structure represented by the following general formula (II) and is characterized by being amorphous.

(In the general formula (II), R ³ is selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and a substituted or unsubstituted aromatic group having 1 to 10 carbon atoms; Is an integer from 1 to 4.)
The photosensitive composition according to one embodiment of the present invention contains a solvent and a matrix compound, and the matrix compound is at least one of a compound represented by the following general formula (I) and a compound represented by the general formula (II). It is characterized by containing.

(Wherein R ¹ and R ² may be the same or different and are each selected from a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and a substituted or unsubstituted aromatic group having 1 to 10 carbon atoms. M1 and m2 are each an integer of 1 to 4. n is an integer of 0 to 2. R ³ is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, or 1 carbon atom. From 10 to 10 substituted or unsubstituted aromatic groups, m3 is an integer from 1 to 4.)
A pattern forming method according to an aspect of the present invention includes a step of forming a photosensitive layer containing the above-described photosensitive composition on a substrate;
Irradiating a predetermined region of the photosensitive layer with ultraviolet rays or ionizing radiation to perform pattern exposure; and
And a step of developing the photosensitive layer after the pattern exposure with an alkaline aqueous solution to selectively remove an unexposed portion of the photosensitive layer.

  ADVANTAGE OF THE INVENTION According to this invention, the photosensitive composition which reacts with high sensitivity with respect to irradiation of an ultraviolet-ray or ionizing radiation, and can develop alkali is provided.

  Embodiments of the present invention will be described below.

  The photosensitive composition according to an embodiment of the present invention contains at least one of a compound having a structure represented by the general formula (I) and a compound having a structure represented by the general formula (II). .

  When a photosensitive layer containing such a photosensitive composition is formed and pattern exposure is performed by irradiating the predetermined region with ultraviolet rays or ionizing radiation, the surface energy selectively changes in the exposed portion. This is explained as follows.

  In the general formulas (I) and (II), (2-hydroxyphenyl) diphenylmethanol is present as a reaction site, and the structure of this site changes upon irradiation with ultraviolet rays or ionizing radiation. As a result, the exposed portion of the photosensitive layer has a reduced solubility in an alkali developer, and only the unexposed portion can be selectively dissolved and removed with the alkali developer to form a pattern. That is, it is a negative type non-chemically amplified resist.

  The compounds represented by the general formulas (I) and (II) are low-molecular compounds containing a structure in which two phenyl groups and one 2-hydroxyphenyl group are substituted for methanol carbon. (2-Hydroxyphenyl) diphenylmethanol itself is known to be crystalline and not crystalline. A crystalline compound cannot be deposited. In other words, even if a crystalline compound is dissolved in a solvent to form a coating film on the substrate, it is not maintained as a film after the solvent is volatilized and removed.

  However, the present inventors have found that the compound represented by the general formula (I) or (II) specifically exhibits amorphous properties and has suitable characteristics as a matrix compound. That is, even after such a compound is dissolved in a solvent to form a coating film on the substrate and the solvent is removed by volatilization, a uniform film can be maintained.

The (2-hydroxyphenyl) diphenylmethanol derivative reacts reversibly as shown in the chemical formula below, and the dehydration reaction proceeds by elimination of the phenolic hydroxy group by irradiation with ultraviolet rays or ionizing radiation. As a result, the surface energy changes greatly.

  When this is applied to a resist, the general formulas (I) and (II) before exposure in the presence of a phenolic hydroxyl group function as a resist that is dissolved in an alkaline aqueous solution. This reaction mechanism is different from conventional resists that decompose or crosslink by the action of an acid catalyst. The dehydration reaction as described above in the (2-hydroxyphenyl) diphenylmethanol derivative is accelerated even in the presence of an acid. Therefore, even if it is in a state where it is mixed with a compound that generates an acid by ultraviolet rays or ionizing radiation such as a photoacid generator, the same action is exhibited.

  Since the photosensitive composition concerning one Embodiment of this invention contains the low molecular compound with a small molecular size as a matrix compound, it will be comprised only with a compound with a small molecular weight. As a result, when a pattern is formed using the resist, the resolution can be increased and the edge roughness can be improved.

  The low molecular weight compound has a small molecular size and a small aggregate size in which molecular chains are entangled. For this reason, in the case of the photosensitive composition comprised only by a low molecular weight compound, the aggregate | assembly which isolate | separates at an exposure part at the time of image development is small, and the edge roughness based on the side wall is reduced. As a result, in the photosensitive composition according to the embodiment of the present invention using the low molecular weight compound, the resolution is increased and the edge roughness can be improved.

  On the other hand, for example, a polymer compound has a large molecular size, and a large size of a network structure aggregate in which molecular chains are entangled. In the case of a photosensitive composition containing a high molecular compound as a matrix compound, a large aggregate of the exposed area is detached during development, resulting in a large edge roughness on the side wall due to the separation of the aggregate. It will be. In the embodiment of the present invention, such a problem is solved.

  In general, when a photosensitive layer containing a photosensitive composition is irradiated with ultraviolet rays or ionizing radiation in a vacuum, degassing such as hydrocarbons is generated from the photosensitive composition, and Contamination of the inside is a problem. In the compounds represented by the general formulas (I) and (II) as described above, hydrocarbons are not generated by the reaction, so that the problem of degassing can be avoided.

In the general formula (I), examples of the alkyl group that can be introduced as R ¹ and R ² include a linear alkyl group such as a methyl group and an ethyl group, a branched alkyl group such as an isopropyl group and a t-butyl group, Examples thereof include a cyclic alkyl group such as a cyclobutyl group, an alkenyl group having an unsaturated bond such as a vinyl group and an allyl group, and an alkynyl group. Examples of the aromatic group include a phenyl group, a naphthyl group, a benzyl group, and a tolyl group. At least one hydrogen atom of such an alkyl group and aromatic group may be substituted with, for example, a hydroxy group, an alkoxy group, an acyl group, a carboxyl group, a carbonyl group, an amino group, a cyano group, a nitro group, or a sulfo group. .

The alkyl group and the aromatic group as described above can be introduced into the general formula (II) as R ³ .

When hydrogen atoms are introduced as all R ¹ and R ² , it is advantageous in that the number of synthesis steps is small and simple when synthesizing a compound. When at least one of the alkyl group and the aromatic group as described above is introduced into at least one of R ¹ and R ² , it is possible to control amorphousness, sensitivity, and solubility in an alkali developer. The same applies to R ³ , and when hydrogen atoms are introduced in all, it is advantageous in that the number of synthesis steps is small and simple when the compound is synthesized. When at least one of an alkyl group and an aromatic group is introduced, it is possible to control amorphousness, sensitivity, and solubility in an alkali developer.

  When the phenyl group is not present, that is, when n = 0, an effect of improving the solubility of the unexposed portion in the alkaline developer can be obtained. On the other hand, when a phenyl group is present, the ability to inhibit dissolution of the exposed portion in an alkaline developer is enhanced. However, the upper limit of n is limited to 2 in order to avoid the inconvenience that the effect of reducing the edge roughness of the pattern decreases as the molecular weight increases.

  The compound having the structure represented by the general formula (I) and the compound having the structure represented by the general formula (II) are compounds obtained by reacting an ortho-bromophenol derivative and a benzophenone skeleton, The reaction can be performed using a strong base such as butyl lithium.

The ortho-bromophenol derivative may contain a substituent, and this substituent will determine R ¹ and R ² in the general formula (I) and R ³ in the general formula (II). Therefore, an ortho-bromophenol derivative as a starting material may be appropriately selected according to the desired effect.

In particular, by introducing electron-donating substituents as R ¹ , R ² , and R ³ , it can be expected to increase sensitivity when used as a resist. Examples of the electron donating substituent include an alkoxy group, an amino group, a hydroxy group, and an aromatic group.

  In the general formula (I), the value of n can be controlled, for example, by changing the reagent used in the synthesis. For example, by using 4,4'-bisbenzoylbiphenyl as a reaction substrate, a compound with n = 0 can be obtained. As a method for increasing the value of n, for example, a dibromo compound used in the coupling reaction is changed.

  The compound represented by the general formula (II) is synthesized by, for example, using 4,4′-dibromobiphenyl as a dibromo compound, coupling with 4-benzoylphenylboric acid, and producing a reaction intermediate. can do.

  The photosensitive composition concerning embodiment of this invention can be prepared by melt | dissolving the photosensitive compound concerning embodiment of this invention in a solvent as a matrix compound, and filtering with a membrane filter etc. If necessary, two or more kinds of matrix compounds may be contained.

  Examples of the solvent include organic solvents such as ketones, cellosolves, and esters. Specifically, examples of the ketone include cyclohexanone, acetone, ethyl methyl ketone, and methyl isobutyl ketone. Examples of cellosolves include methyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, and butyl cellosolve acetate. Examples of the esters include ethyl acetate, butyl acetate, isoamyl acetate, γ-butyrolactone, and methyl 3-methoxypropionate. The above-mentioned solvents can be used in combination of two or more as necessary.

  Depending on the type of photosensitive composition, dimethyl sulfoxide, N, N-dimethylformamide, N-methylpyrrolidinone, anisole, monochlorobenzene, or orthodichlorobenzene may be used as part of the solvent to improve solubility. You can also. Furthermore, lactic acid esters such as ethyl lactate, propylene glycol monoethyl acetate and the like may be used as the low toxicity solvent.

  Basically, the photosensitive composition according to the embodiment of the present invention is prepared by at least one of the compound represented by the general formula (I) and the compound represented by the general formula (II) and a solvent.

The photosensitive composition according to the embodiment of the present invention may further contain a photoacid generator. In this case, a negative chemically amplified resist is obtained. The photoacid generator is a compound that generates an acid by the action of ultraviolet rays or ionizing radiation. As the photoacid generator, sulfonyl, iodonium, and other onium salt compounds and sulfonyl esters are preferably used. Preferable specific examples of the photoacid generator include the following.

Here, R ¹⁰ , R ¹¹ and R ¹² may be the same or different and are selected from a substituted or unsubstituted alkyl group and a substituted or unsubstituted aryl group.

Here, Z is a substituent selected from a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, and a halogen atom, and X ⁺ -is any cationic group. is there. n is an integer of 1 to 3 such that the total charge of the cationic group is +1.

  The photoacid generators may be used alone or in combination of two or more. If the content of the photoacid generator is generally 0.1% by weight of the total weight of the solid components contained in the photosensitive composition, the effect can be obtained. The solid component refers to a composition obtained by removing the organic solvent component from the photosensitive composition. When the content of the photoacid generator is too small, it is difficult to obtain sufficient sensitivity. In particular, irradiation with ionizing radiation requires more photoacid generators than ultraviolet rays.

  On the other hand, when there is too much photoacid generator, for example, in the case of exposure with ArF excimer light, the light transmittance of the photosensitive composition at the exposure wavelength may be impaired by light absorption of the photoacid generator itself. In order to avoid such inconvenience, it is desired that the content of the photoacid generator is limited to 10.0% by weight at the maximum.

  Various additives can be mix | blended with the photosensitive composition concerning embodiment of this invention as needed. For example, in order to reduce the influence of the basic compound in the environment, which is a drawback of the chemically amplified resist, a trace amount of the basic compound may be added.

  Examples of basic compounds include pyridine derivatives, aniline derivatives, amine compounds, and indene derivatives. Examples of pyridine derivatives include t-butylpyridine, benzylpyridine, and various pyridinium salts. Examples of aniline derivatives include N-methylaniline, N-ethylaniline, and N, N′-dimethylaniline. Can be mentioned. Examples of the amine compound include diphenylamine and N-methyldiphenylamine.

  If the basic compound is blended in an amount of 10% or more of the number of moles of the photoacid generator, the effect can be obtained. When the amount of the basic compound is too large, the sensitivity of the photosensitive composition may be lowered. Therefore, it is desirable that the addition amount be limited to 70% of the number of moles of the photoacid generator at the maximum. What is necessary is just to adjust the addition amount of a basic compound suitably according to the patterning apparatus etc. to be used.

  When forming a pattern using the photosensitive composition concerning embodiment of this invention, first, a photosensitive composition is apply | coated on a board | substrate and a photosensitive layer is formed. Any substrate can be used. Specifically, as a substrate, a silicon wafer, a doped silicon wafer, a silicon wafer having various insulating films, electrodes, or wirings formed on its surface, a mask blank, a III-V group compound semiconductor wafer such as GaAs or AlGaAs, etc. And so on. Further, a chromium or chromium oxide deposition substrate, an aluminum deposition substrate, an IBSPG coated substrate, an SOG coated substrate, or a SiN coated substrate can be used.

  Arbitrary methods can be adopted to apply the photosensitive composition on such a substrate, and examples thereof include spin coating, dip coating, doctor blade method, and curtain coating.

  The applied photosensitive composition is dried by heating to form a photosensitive layer. Even when the matrix compound substituent and the photoacid generator are unexposed, they undergo a decomposition reaction upon heating at a high temperature, and thus react. Therefore, the heat drying temperature is preferably 170 ° C. or lower. ° C is preferred.

  Next, pattern exposure is performed by irradiating a predetermined region of the photosensitive layer with ultraviolet rays or ionizing radiation. The exposure can be performed by irradiating the photosensitive layer with ultraviolet rays or ionizing radiation through a predetermined mask pattern. Alternatively, exposure may be performed by directly scanning the photosensitive layer with ionizing radiation without using a mask pattern.

  The ionizing radiation used for exposure may be any as long as the photosensitive composition according to the embodiment of the present invention has a wavelength with sensitivity.

  Specifically, ultraviolet rays, mercury lamp i-line, h-line, or g-line, xenon lamp light, deep ultraviolet UV light (for example, excimer laser light such as KrF or ArF), X-ray, synchrotron orbital radiation (SR) Electron beams, γ rays, ion beams, and the like can be used.

  The exposed photosensitive layer is developed with an alkali developer. However, when a photo-acid generator is added to form a chemically amplified resist, heat treatment (post-exposure baking) is performed on the exposed photosensitive layer in order to promote the acid-catalyzed reaction. The post-exposure bake treatment can be performed by any method applied to the chemically amplified resist, and may be performed by heating on a hot plate or in a heating furnace, or by infrared irradiation. Usually, the temperature of the heat treatment is 50 ° C. or higher, but it is desired that the upper limit of the heating temperature be suppressed to about 150 ° C. in order to suppress excessive diffusion of the acid.

  As an alkali developer for development processing, either an organic alkali aqueous solution or an inorganic alkali aqueous solution may be used. Examples of the organic alkaline aqueous solution include a tetramethylammonium hydroxide aqueous solution, a tetraethylammonium hydroxide aqueous solution, and a choline aqueous solution. Examples of the inorganic alkaline aqueous solution include a potassium hydroxide aqueous solution and a sodium hydroxide aqueous solution.

  The concentration of the alkali developer is not limited, but the concentration may be 15 mol% or less in order to increase the dissolution rate difference between the exposed and unexposed portions of the photosensitive layer and ensure sufficient dissolution contrast. preferable. This concentration needs to be adjusted according to the amount of protecting groups introduced into the matrix compound.

  Moreover, arbitrary additives can also be added to these developers as necessary. For example, a surfactant can be added to lower the surface tension of the developer, or a neutral salt can be added to activate development. As the surfactant, for example, the following can be used. Specifically, polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene polyoxypropylene alkylphenyl ether, polyoxyethylene glycol, polyoxyethylene polyoxypropylene glycol, Polyoxypropylene glycol, polyoxyethylene fatty acid ester, polyoxyethylene sorbitan fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid monoester, sucrose fatty acid ester, fatty acid alkanolamide, polyoxyethylene alkylamide, polyoxyethylene polyoxypropylene alkylamide , Polyoxyethylene alkylamino ether, polyoxyethylene polyoxyp Nonionic surfactants such as pyrene alkylamino ether, polyoxyethylene acetylene glycol, polyoxyethylene polyoxypropylene acetylene glycol, alkyl phosphate ester salt, monoalkylamine and its salt, alkyltrimethylamine and its salt, dialkyldimethylamine and Salts thereof, imidazolinium and salts thereof, alkylbenzyldimethyl quaternary ammonium and salts thereof, benzylpyridinium and salts thereof, alkylpyridinium and salts thereof, and cationic surfactants such as polyoxyethylene alkylbenzylammonium.

  Examples of neutral salts include tetraalkylammonium, such as tetramethylammonium, trimethylethylammonium, tetraethylammonium, trimethylhydroxyethylammonium, methyltrihydroxyethylammonium, dimethyldihydroxyethylammonium, dimethylamine, trimethylamine, monoethylamine, diethylamine and the like. And carbonates and hydrogencarbonates of alkanolamines such as ethanolamine, diethanolamine and triethanolamine. The temperature of the developer is also arbitrary and may be appropriately determined within the range of 0 to 100 ° C.

  In the pattern formation method of this invention, a process can also be added as needed. For example, a step of forming a planarization layer before coating a photosensitive layer on a substrate, a step of forming an antireflection layer for reducing the reflection of exposure light, and washing the substrate after development with water or the like In addition, a rinsing step for removing a developing solution or the like can be combined with the above-described steps.

  As described above, the photosensitive layer containing the photosensitive composition according to the embodiment of the present invention is formed, and pattern exposure and development treatment are performed to selectively dissolve the unexposed portion of the photosensitive layer. Removed. As a result, a resist pattern is formed. Since the photosensitive composition according to the embodiment of the present invention is used, the pattern according to the embodiment of the present invention can be resolved with an alkali developer as a non-chemically amplified resist, and can be formed with high sensitivity. Is possible.

  Specific examples of the present invention are shown below.

(Synthesis Example 1)
A normal-butyllithium hexane solution (1.6 M, 8.2 ml) was placed in a glass container whose interior was purged with nitrogen, and cooled to 0 ° C. in an ice bath. Ortho-bromophenol (0.76 ml) was added dropwise thereto, the ice bath was removed, and the mixture was reacted at room temperature for 2 hours. Next, the reaction vessel was cooled in a dry ice-methanol bath, and 4,4′-bisbenzoylbiphenyl (1.00 g) dissolved in a dehydrated ether-toluene mixed solvent (ether: toluene = 4: 3, 50 ml) was added to 10 It was added dropwise over a period of minutes.

  Thereafter, the reaction was carried out in an ice bath at 0 ° C. for 3 hours, and a saturated aqueous ammonium chloride solution was added dropwise. Ether was added to the separatory funnel, and the organic layer was washed several times with pure water and then with a saturated aqueous sodium chloride solution. Sodium sulfate was added to the obtained organic layer, followed by filtration to remove sodium sulfate. The solvent was removed with a rotary evaporator and reprecipitation was performed in hexane to obtain a white solid. The resulting solid was filtered with suction and dried in vacuo to give a pure product.

The spectrum of ¹ H-NMR measurement is as follows.

¹ H-NMR (δ, 270 MHz, chloroform-d): 3.70 (s, 2H), 6.49 (d, 2H), 6.73-6.96 (m, 6H), 7.10-7 .58 (m, 14H), 7.84 (s, 2H)
The product is represented by the following chemical formula: 4- (4 ′ ″-{2- [hydroxy- (2-hydroxyphenyl) -phenyl-methyl]} [1,1 ′; 4 ′, 1 ″] biphenyl)- (2-hydroxyphenyl) -phenyl-methanol (hereinafter referred to as HDM-1)).

(Synthesis Example 2)
4,4′-Dibromobiphenyl (1.56 g), 4-benzoylphenyl boric acid (3.39 g), and potassium carbonate (2.07 g) were placed in a reaction vessel, and the system was purged with nitrogen. Then tetrahydrofuran (50 ml) and tetrakis (triphenylphosphine) palladium (0.1 g) were added and stirred until dissolved.

After refluxing for 8 hours, the solvent was removed with a rotary evaporator. Toluene was added to the obtained white solid, and it was heated to 100 ° C. and filtered before cooling. Thereafter, the solvent of the mother liquor was removed and washed with cold toluene. The filtrate was cooled and recrystallized to give (4 ′ ″-benzoyl- [1,1 ′; 4 ′, 1 ″; 4 ″, 1 ′ ″] quaterphenyl-4-yl) -phenylmeta as a white solid. Got non. ¹ H-NMR (δ, 270 MHz, chloroform-d): 7.50-7.95 (m, 26H).

  A normal-butyllithium hexane solution (1.6 M, 8.2 ml) was placed in a glass container in which the system was purged with nitrogen, and cooled to 0 ° C. in an ice bath. Ortho-bromophenol (0.76 ml) was added dropwise thereto, the ice bath was removed, and the mixture was reacted at room temperature for 2 hours. Next, the reaction vessel was cooled with a dry ice-methanol bath and dissolved in a dehydrated ether-toluene mixed solvent (ether: toluene = 3: 10, 26 ml) (4 ′ ″-benzoyl- [1,1 ′). 4 ′, 1 ″; 4 ″, 1 ′ ″] quaterphenyl-4-yl) -phenylmethanone (1.43 g) was added dropwise over 10 minutes.

  Then, it was made to react for 1 hour with a 0 degreeC ice bath, and saturated ammonium chloride aqueous solution was dripped. Ether was added to the separatory funnel, and the organic layer was washed several times with pure water and then with a saturated aqueous sodium chloride solution. Sodium sulfate was added to the obtained organic layer, followed by filtration to remove sodium sulfate. The solvent was removed with a rotary evaporator and reprecipitation was performed in hexane to obtain a white solid. The resulting solid was filtered with suction and dried in vacuo to yield the pure product.

The results of ¹ H-NMR measurement are as follows.

¹ H-NMR (δ, 270 MHz, chloroform-d): 3.64 (s, 2H), 6.47 (d, 2H), 6.56 (t, 2H), 6.82 (d, 2H), 7.02-7.53 (m, 26H), 8.03 (s, 2H).

The product is represented by the following chemical formula: (4- (4 ′ ″-{2- [hydroxy- (2-hydroxyphenyl) -phenyl-methanol]} [1,1 ′; 4 ′, 1 ″; 4 ″ , 1 ′ ″] quarterphenyl)-(2-hydroxyphenyl) -phenylmethanol (hereinafter referred to as HDM-2)).

(Synthesis Example 3)
A normal-butyllithium hexane solution (1.6 M, 8.2 ml) was placed in a glass container in which the system was purged with nitrogen, and cooled to 0 ° C. in an ice bath. Ortho-bromophenol (0.76 ml) was added dropwise thereto, the ice bath was removed, and the mixture was reacted at room temperature for 2 hours. Next, the reaction vessel was cooled with a dry ice-methanol bath, and 4-benzoylbiphenyl (1.68 g) dissolved in a dehydrated ether-toluene mixed solvent (ether: toluene = 4: 3, 35 ml) was taken over 10 minutes. And dripped.

  Then, it was made to react for 1 hour with a 0 degreeC ice bath, and saturated ammonium chloride aqueous solution was dripped. Ether was added to the separatory funnel, and the organic layer was washed several times with pure water and then with a saturated aqueous sodium chloride solution. Sodium sulfate was added to the obtained organic layer, followed by filtration to remove sodium sulfate. The solvent was removed with a rotary evaporator and reprecipitation was performed in hexane to obtain a white solid. The resulting white solid was filtered off with suction and a pure white product was obtained after drying in vacuo.

The results of ¹ H-NMR measurement are as follows.

¹ H-NMR (δ, 270 MHz, chloroform-d): 3.90 (s, 1H), 6.60-7.96 (m, 18H), 8.08 (s, 1H).

The white product was identified as (2-hydroxy) -4-biphenyl-diphenylmethanol (hereinafter referred to as HDM-3) represented by the following chemical formula.

  As described above, three types of (2-hydroxyphenyl) biphenylmethanol derivatives of HDM-1, HDM-2, and HDM-3 were synthesized. Resist solutions 1, 2, and 3 were prepared by dissolving the derivative as a matrix compound in a solvent. As the solvent, methyl methoxypropionate was used, and the amount of the matrix compound was 6 wt% with respect to the solvent.

(Examples 1-3)
A resist film was formed using the prepared resist solution and patterned. Specifically, a resist solution was applied onto a silicon wafer by spin coating to form a resist film having a thickness of about 100 nm. The obtained resist film was baked at 60 ° C. for 90 seconds, and then subjected to pattern exposure with an ultraviolet lamp.

After the exposure, development was performed with an aqueous tetramethylammonium hydroxide (TMAH) solution to obtain a negative pattern. The resolution of the obtained pattern is summarized in Table 1 below together with the development processing conditions.

  When pattern formation is performed on a film using the photosensitive composition according to the embodiment of the present invention, it is possible to form a pattern by alkali development. In view of the reaction mechanism, it can be easily estimated that it is sensitive to EUV light of soft X-rays (13 nm). Therefore, the photosensitive composition according to the embodiment of the present invention can be sufficiently applied to future EUV lithography.

  Further, each resist solution was applied on a substrate by spin coating to form a coating film, and the surface state was observed with an optical microscope. All the coating films obtained using the resist solutions 1, 2, and 3 were kept as films, and were confirmed to exhibit amorphous properties.

  For comparison, an attempt was made to form a coating film by a similar method using a resist solution obtained by dissolving (2-hydroxyphenyl) biphenylmethanol in methyl methoxypropionate. As a result of observing the surface with an optical microscope, it was confirmed that the surface was island-shaped and not kept as a film.

Example 4
A resist solution 4 was prepared by adding a photoacid generator to the resist solution 1 described above. Triphenylsulfonium triflate was used as the photoacid generator, and the blending amount was 5 wt% with respect to the matrix compound. Since the photoacid generator is blended, the resist solution 4 is a chemically amplified resist.

  The resist solution 4 was applied onto a silicon wafer by spin coating to form a resist film having a thickness of about 100 nm. The obtained resist film was baked at 60 ° C. for 90 seconds, and then exposed with KrF excimer laser light to perform pattern size half pitch 1 μm line and space exposure.

Thereafter, development was performed with an aqueous tetramethylammonium hydroxide (TMAH) solution to obtain a negative pattern. Table 2 shows the development processing conditions and sensitivity. For reference, data on the resist solution 1 containing no photoacid generator is also shown in Table 2 together.

  As is apparent from the above results, it can be seen that the sensitivity can be increased by adding a photoacid generator to a chemically amplified resist. Since a similar effect can be obtained by using a light source that reacts with a photoacid generator, it can be easily estimated from the reaction mechanism that the sensitivity is increased even if the light source is other than a KrF excimer laser.

  As a light source applied to the chemically amplified resist, specifically, ultraviolet rays, mercury lamp i-line, h-line or g-line, xenon lamp light, deep ultraviolet UV light (for example, excimer laser light such as KrF or ArF), Examples include X-ray, synchrotron orbital radiation (SR), electron beam, γ-ray, ion beam, soft X-ray (13 nm) EUV light, and the like.

(Example 5)
The resist solution 1 was applied onto a silicon wafer by spin coating to form a resist film having a thickness of about 100 nm. After the obtained resist film was baked at 60 ° C. for 90 seconds, pattern drawing was performed with an electron beam drawing apparatus (electron beam acceleration voltage was 30 keV).

Development with an aqueous tetramethylammonium hydroxide (TMAH) solution gave a negative pattern. The resolution and sensitivity of the obtained pattern are summarized in Table 3 together with the conditions for development processing.

As shown in Table 3 above, the photosensitive composition according to the embodiment of the present invention can be developed with an alkaline aqueous solution, and can form a pattern with high sensitivity. When pattern formation is attempted under the same conditions using a resist made of calixarene or a fullerene derivative, the sensitivity is about 1 mC / cm ² and ² mC / cm ² , respectively, and the developer is an organic solvent. Are known.

(Examples 9 to 11)
Resist solutions 1 to 3 were each applied onto a silicon wafer by spin coating to form a resist film having a thickness of about 100 nm. After the obtained resist film was baked at 60 ° C. for 90 seconds, the contact angle was measured. In measuring the contact angle, first, a water droplet was dropped on the resist film using a syringe. A photograph of a water drop from a horizontal plane was taken, and the contact angle was determined from the height of the top of the water drop and the length of the bottom.

Thereafter, the entire resist film was exposed with an ultraviolet lamp, and the contact angle was measured again by the same method. Here, the exposure amount of the lamp was 288 μJ / cm ² . After heating at 100 ° C. for 90 seconds on a hot plate, the contact angle was measured again by the same method. The results are summarized in Table 4 below. It was confirmed that the hydrophilicity / hydrophobicity of the surface of the photosensitive layer can be reversibly converted.

  As shown in Table 4 above, the photosensitive compound according to the embodiment of the present invention undergoes a photoisomerization reaction, and the value of the contact angle, that is, the hydrophilicity / hydrophobicity of the surface changes when irradiated with light. It is restored again by heating. Therefore, since the hydrophilicity / hydrophobicity of the surface changes reversibly, pattern exposure is performed on the photosensitive layer containing the photosensitive composition of the present invention to form a latent image, and the obtained latent image is transferred. Thus, it is possible to repeatedly form images using ink. Specifically, the photosensitive composition according to the embodiment of the present invention can be suitably used as a material for an image carrier portion of an image forming apparatus such as a copying machine or a printer.

Claims (6)

A photosensitive compound comprising a structure represented by the following general formula (I) and exhibiting amorphous properties.

(In the general formula (I), R ¹ and R ² may be the same or different, and are a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and a substituted or non-substituted group having 1 to 10 carbon atoms. (Selected from substituted aromatic groups. M1 and m2 are integers of 1 to 4. n is an integer of 0 or more and 2 or less.) A photosensitive compound comprising a structure represented by the following general formula (II) and exhibiting amorphous properties.

(In the general formula (II), R ³ is selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and a substituted or unsubstituted aromatic group having 1 to 10 carbon atoms; Is an integer from 1 to 4.) A photosensitive composition comprising a solvent and a matrix compound, wherein the matrix compound contains at least one of a compound represented by the following general formula (I) and a compound represented by the general formula (II).

(Wherein R ¹ and R ² may be the same or different and are each selected from a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and a substituted or unsubstituted aromatic group having 1 to 10 carbon atoms. M1 and m2 are each an integer of 1 to 4. n is an integer of 0 to 2. R ³ is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, or 1 carbon atom. From 10 to 10 substituted or unsubstituted aromatic groups, m3 is an integer from 1 to 4.)   4. The photosensitive composition according to claim 3, further comprising a photoacid generator that generates an acid by ultraviolet rays or ionizing radiation. Forming a photosensitive layer containing the photosensitive composition according to claim 3 on a substrate;
Irradiating a predetermined region of the photosensitive layer with ultraviolet rays or ionizing radiation to perform pattern exposure; and
And a step of developing the photosensitive layer after the pattern exposure with an alkaline aqueous solution to selectively remove an unexposed portion of the photosensitive layer.   The photosensitive composition further includes a photoacid generator that generates an acid by ultraviolet rays or ionizing radiation, and further includes a step of heat-treating the photosensitive layer after the pattern exposure and before the development processing. The pattern forming method according to claim 5.