JP2009204985A - Compound for photoresist, photoresist solution, and etching method using the photoresist solution - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new compound for photoresist, which is used to perform microfabrication by photolithography, a photoresist solution using the compound for photoresist, and to provide an etching method for etching a surface of interest by using the photoresist solution. <P>SOLUTION: The compound for photoresist is a compound represented by general formula (I), wherein R<SP>1</SP>and R<SP>2</SP>each independently represent a substituent having a Hammett's substituent constant σp in a range of 0.2-0.9; R<SP>3</SP>represents a hydrogen atom or a monovalent substituent; Φ represents a substituted or unsubstituted aryl group or an aromatic heterocyclic group; and two or more of R<SP>1</SP>, R<SP>2</SP>, R<SP>3</SP>and Φ may bond to each other to form a ring. The photoresist solution contains the compound for photoresist. The etching method is for etching a surface to be processed by using the photoresist solution. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a photoresist compound and a photoresist solution capable of forming a fine pattern. Furthermore, this invention relates to the etching method of the to-be-processed surface using the said photoresist liquid.

In the manufacturing process of electronic parts such as semiconductor elements, magnetic bubble memories, and integrated circuits, a technique of forming a fine pattern and using this as an etching mask to etch the underlying surface is widely used.
In recent years, light-emitting elements such as LEDs have been utilized for various applications. This LED is a semiconductor element in which a semiconductor multilayer film including a light emitting layer is laminated on a substrate (hereinafter also referred to as “chip”), which is packaged with a resin or the like. Since the refractive index of the upper layer (or outermost layer) is different from that of the resin of the package, reflection occurs at the interface between the two and the luminous efficiency is lowered. Therefore, in order to prevent such reflection at the interface and improve the light emission efficiency, it has been proposed to provide a fine concavo-convex structure on the surface of the light extraction port of the chip (for example, Patent Document 1 and 2).
JP 2003-174191 A JP 2003-209283 A

In Patent Document 1, in the fifth embodiment, an antireflection film is provided as the uppermost layer constituting the light extraction port of the light emitting diode, and a fine uneven shape is formed on the surface of the antireflection film in advance. As a method of manufacturing a mold having a fine concavo-convex shape, press-molding the surface of the antireflection film with this mold, and forming a concavo-convex shape on the surface of the light extraction port, or a modification thereof, A method of roughening the surface of the antireflection film in a random direction with a grinder instead of press molding using a mold is disclosed. However, the former method requires a cumbersome process of creating a mold and has the disadvantage of costly mold production. The latter method is difficult to always make a uniform rough surface, There was a problem that the product had performance variations.
On the other hand, in Patent Document 2, a line-and-space pattern having a triangular cross section is formed on the current diffusion layer constituting the uppermost layer of the light extraction port of the semiconductor element by blade processing, and the hydrochloric acid treatment at a high temperature is performed to treat the current diffusion layer. A method of forming submicron irregularities on the surface and a line and space pattern using a photoresist on the current diffusion layer, and further applying the minute irregularities similar to the above to the current by reactive ion etching (RIE) A method of forming on the surface of the diffusion layer is disclosed. However, these methods also have a problem that a complicated process is required.

  Conventionally, photolithography is known as a technique used for manufacturing a fine concavo-convex structure and a semiconductor device. In photolithography, a resist composition containing a photosensitive compound is applied to the surface of a substrate or the like, then pattern exposure is performed through a photomask, and then development is performed to selectively select either an exposed portion or a non-exposed portion. Then, a resist pattern is formed. Thereafter, by using this resist pattern as an etching mask, a fine uneven pattern or a semiconductor element can be formed on the surface of a substrate or the like.

  However, in photolithography using a photoresist solution containing a conventional photosensitive compound, a step of developing after pattern exposure is essential, and the number of steps increases accordingly.

Accordingly, an object of the present invention is to provide a novel photoresist compound used for fine processing utilizing photolithography, more specifically, a novel photoresist capable of omitting a development process after pattern exposure. It is to provide a compound for use.
Another object of the present invention is to provide a photoresist solution using the above-mentioned photoresist compound.
Still another object of the present invention is to provide an etching method for etching a desired surface using the above-described photoresist solution.

  As a result of intensive investigations to achieve the above object, the present inventors have made a pattern exposure to a dye film containing an arylidene dye. As a result, the dye film after pattern exposure was found to be usable as an etching mask, and the present invention was completed.

[一般式(I)中、Ｒ¹およびＲ²は、それぞれ独立に、ハメットの置換基定数σｐが０．２〜０．９の範囲の置換基を表し、Ｒ³は水素原子または一価の置換基を表し、Φは置換または無置換のアリール基または芳香族ヘテロ環基を表し、Ｒ¹、Ｒ²、Ｒ³およびΦのうちの何れか二つ以上が互いに結合して環を形成していてもよい。]
[２]一般式(I)中、Φがハメットの置換定数σpが−１．０〜０．０の範囲の置換基を有するアリール基または芳香族ヘテロ環基を表す[１]に記載のフォトレジスト用化合物。
[３]熱分解温度が１５０℃以上５００℃以下である[１]または[２]に記載のフォトレジスト用化合物。
[４][１]〜[３]のいずれかに記載のフォトレジスト用化合物を含むフォトレジスト液。
[５]前記フォトレジスト用化合物を、前記フォトレジスト液に含まれる全固形分を基準として５０質量％以上含有する[４]に記載のフォトレジスト液。
[６][４]または[５]に記載のフォトレジスト液を被加工表面に塗布してフォトレジスト膜を形成すること、
上記フォトレジスト膜にパターン露光すること、および、
上記パターン露光後のフォトレジスト膜を有する被加工表面の少なくとも一部にエッチング処理を施し、上記パターン露光において露光された部分に対応する領域における被加工表面の少なくとも一部をエッチングすること
を含む被加工表面のエッチング方法。
[７]前記パターン露光に使用される光は、λｎｍの波長を有するレーザー光であり、前記フォトレジスト膜に含まれる前記フォトレジスト用化合物の最大吸収波長λｍａｘはλ±１５０ｎｍの範囲にある[６]に記載の被加工表面のエッチング方法。 That is, the above object has been achieved by the following means.
[1] A photoresist compound, which is a compound represented by the following general formula (I):

[In the general formula (I), R ¹ and R ² each independently represent a substituent having a Hammett's substituent constant σp of 0.2 to 0.9, and R ³ represents a hydrogen atom or a monovalent Φ represents a substituted or unsubstituted aryl group or an aromatic heterocyclic group, and any two or more of R ¹ , R ² , R ³ and Φ are bonded to each other to form a ring. It may be. ]
[2] The photo of [1], wherein in general formula (I), Φ represents an aryl group or aromatic heterocyclic group having a substituent having a Hammett substitution constant σp in the range of −1.0 to 0.0. Resist compound.
[3] The photoresist compound according to [1] or [2], which has a thermal decomposition temperature of 150 ° C. or higher and 500 ° C. or lower.
[4] A photoresist solution containing the photoresist compound according to any one of [1] to [3].
[5] The photoresist solution according to [4], containing the photoresist compound in an amount of 50% by mass or more based on the total solid content in the photoresist solution.
[6] Forming a photoresist film by applying the photoresist liquid according to [4] or [5] to a surface to be processed;
Pattern exposure to the photoresist film; and
Etching at least a part of the processing surface having the photoresist film after the pattern exposure, and etching at least a part of the processing surface in a region corresponding to the part exposed in the pattern exposure. Process surface etching method.
[7] The light used for the pattern exposure is a laser beam having a wavelength of λ nm, and the maximum absorption wavelength λmax of the photoresist compound contained in the photoresist film is in the range of λ ± 150 nm. ] The etching method of the to-be-processed surface of description.

  According to the present invention, it is possible to form an etching mask only by pattern exposure, in other words, without going through a developing step with a developer, so that a photo that is performed multiple times in the process of manufacturing various semiconductor devices. Each development process of the lithography process can be eliminated, and thereby a great simplification can be achieved. Furthermore, according to the present invention, fine irregularities can be formed on the surface to be processed.

[Photoresist compound]
The photoresist compound of the present invention is a compound represented by the following general formula (I).

[一般式(I)中、Ｒ¹およびＲ²は、それぞれ独立に、ハメットの置換基定数σｐが０．２〜０．９の範囲の置換基を表し、Ｒ³は水素原子または一価の置換基を表し、Φは置換または無置換のアリール基または芳香族ヘテロ環基を表し、Ｒ¹、Ｒ²、Ｒ³およびΦのうちの何れか二つ以上が互いに結合して環を形成していてもよい。]

[In the general formula (I), R ¹ and R ² each independently represent a substituent having a Hammett's substituent constant σp of 0.2 to 0.9, and R ³ represents a hydrogen atom or a monovalent represents a substituent, [Phi represents a substituted or unsubstituted aryl group or an aromatic heterocyclic group, R ^1, R ^2, or two or more of R ³ and [Phi is bonded to each other to form a ring It may be. ]

The present inventors have found that a coating film containing the above compound (hereinafter also referred to as “arylidene compound”) undergoes local changes in physical properties when irradiated with light, and the coating film before light irradiation. It was found that the etching resistance is lower than that of the coating film, and that the coating film can function as an etching mask. The present inventors estimate this phenomenon as follows.
When the coating film containing the arylidene compound is irradiated with light, for example, with a laser beam in a spot shape, the arylidene compound generates heat in the light irradiation portion. As a result of this heat generation, the arylidene compound undergoes changes in physical properties such as thermal decomposition. As a result, the irradiated part of the coating film locally changes physically and / or chemically, resulting in a decrease in pit (opening) and local durability. A part (low durability part) is considered to be formed. The coating film on which the pits are formed not only functions as an etching mask, but also the low durability part is etched more easily in the etching process, so the coating film in which the low durability part is formed by pattern exposure. Can also function as an etching mask. It has also been found that the coating film itself containing the above arylidene compound has excellent etching resistance and can function well as a durable film against etching. Here, the etching method may be dry etching or wet etching. In particular, the present invention is preferably applied to dry etching because a wet etching solution cleaning step is unnecessary.
In particular, when the present inventors observed the behavior of the coating film containing the above arylidene compound during irradiation with laser light, the temperature rises at the central portion of the light irradiated portion of the laser beam, and the phenomenon that the temperature decreases at the peripheral portion is observed. confirmed. The reason for the temperature drop in the peripheral part is not clear, but due to the temperature drop in the peripheral part, pit formation and low durability part formation due to thermal decomposition occur in the central part of the laser light irradiation part, but physical property changes to the peripheral part Therefore, it is considered that a pattern having a diameter smaller than the beam diameter of the laser beam can be formed on the coating film by pattern exposure with laser light. Therefore, by pattern exposure with a laser beam on the coating film, only an exposure area with a small diameter that is much narrower than the area irradiated with the laser beam becomes a low-durability part, resulting in a beam that is thinner than the laser beam diameter. Fine pattern exposure similar to the case of pattern exposure can be achieved.
Furthermore, the coating film containing the arylidene compound forms a pit or a low durability portion at the irradiated portion by pattern exposure, so that development processing after the pattern exposure is unnecessary, and an etching process is performed after the pattern exposure. be able to.
The “photoresist” in the present invention includes an embodiment in which a resist pattern is formed by heat generated by such pattern exposure.

  The photoresist compound of the present invention is a compound represented by the above general formula (I). Hereinafter, the general formula (I) will be described in more detail.

In general formula (I), R ¹ and R ² each independently represent a substituent having a Hammett's substituent constant σp in the range of 0.2 to 0.9. If R ¹ and R ² are electron withdrawing groups having Hammett's substitution constant σp in the above range, absorption characteristics and thermal decomposability suitable as a photoresist compound can be achieved. Hammett's substituent constant σp of the substituent represented by R ¹ and R ² is more preferably 0.30 to 0.85, and most preferably 0.35 to 0.80.

Hammett's substituent constant σp value (hereinafter referred to as σp value) is described, for example, in Chem. Rev. 91, 165 (1991) and references cited therein, and those not described can be obtained by the method described in the same document. If R ¹ and R ² form a ring, .sigma.p value of R ¹ means a .sigma.p value of -R ¹ -R ² -H group, .sigma.p value for R ^2, -R ² This means the σp value of the —R ¹ —H group. In this case, both have different σp values because of different coupling directions.

Specific examples of the electron withdrawing group represented by R ¹ and R ² include cyano group, nitro group, acyl group, alkoxycarbonyl group, carbamoyl group, sulfonyl group, sulfonyl group, alkoxysulfonyl group, sulfamoyl group, sulfinyl. Group, sulfenyl group, halogen atom, alkynyl group, diacylamino group, phosphoryl group, carboxyl group, heterocyclic group (for example, 2-benzothiazolyl group, 2-benzoxazolyl group, 3-pyridyl group, 5- (1H ) -Tetrazolyl group, 4-pyrimidyl group). R ¹ and R ² may be the same or different from each other.

R ³ represents a hydrogen atom or a monovalent substituent. Examples of the monovalent substituent include a linear or cyclic alkyl group having 1 to 20 carbon atoms (for example, a methyl group, an ethyl group, an isopropyl group, a cyclohexyl group), a substituted or unsubstituted group having 6 to 18 carbon atoms. Aryl groups (for example, phenyl group, chlorophenyl group, anisyl group, toluyl group, 2,4-di-t-amyl group, 1-naphthyl group), alkenyl groups (for example, vinyl group, 2-methylvinyl group), Alkynyl group (for example, ethynyl group, 2-methylethynyl group, 2-phenylethynyl group), halogen atom (for example, F, Cl, Br, I), cyano group, hydroxyl group, carboxyl group, acyl group (for example, acetyl group) Group, benzoyl group, salicyloyl group, pivaloyl group), alkoxy group (for example, methoxy group, butoxy group, cyclohexyloxy group), Reeloxy group (for example, phenoxy group, 1-naphthoxy group), alkylthio group (for example, methylthio group, butylthio group, benzylthio group, 3-methoxypropylthio group), arylthio group (for example, phenylthio group, 4-chlorophenylthio group) ), Alkylsulfonyl group (for example, methanesulfonyl group, butanesulfonyl group), arylsulfonyl group (for example, benzenesulfonyl group, paratoluenesulfonyl group), carbamoyl group having 1 to 10 carbon atoms, or 1 to 10 carbon atoms Amido group, acyloxy group having 2 to 10 carbon atoms, alkoxycarbonyl group having 2 to 10 carbon atoms, heterocyclic group (for example, aromatic such as pyridyl group, thienyl group, furyl group, thiazolyl group, imidazolyl group, pyrazolyl group, etc. Group heterocyclic group, pyrrolidine ring, piperidy Ring, morpholine ring, pyran ring, thiopyran ring, dioxane ring, and dithiolane aliphatic heterocyclic group such as rings). In the present invention, “the number of carbon atoms” for a certain group means the number of carbon atoms in a portion not containing the substituent when the group has a substituent.
R ³ is preferably a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms, more preferably a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or phenyl, and a hydrogen atom being Particularly preferred.

  Φ represents a substituted or unsubstituted aryl group or an aromatic heterocyclic group.

  Examples of the aryl group represented by Φ include a phenyl group and a naphthyl group.

The aromatic heterocyclic group represented by Φ is preferably an aromatic heterocyclic group having 4 to 9 carbon atoms, and the hetero atom contained therein is preferably a nitrogen atom, an oxygen atom or a sulfur atom, particularly a nitrogen-containing aromatic. A group heterocyclic group is preferable, for example, 2-pyridyl group, 3-pyridyl group, 2-pyrazyl group, 2-imidazolyl group, 2-pyrrolyl group, 2-furyl group, 2-thiophenyl group, 3-indolyl group, 4- A quinolinyl group and a 2-isoquinolinyl group can be mentioned.
Φ is preferably a substituted or unsubstituted aryl group, more preferably a substituted or unsubstituted phenyl group, still more preferably a substituted phenyl group, and is substituted with an electron donating group described later. Most preferred is a phenyl group.

Each group described above as R ¹ , R ² , R ³ and Φ may further have a substituent, and examples of the substituent include those described as examples of R ^{3 in} the general formula (I). it can. As the substituent when Φ is a substituted aryl group or a substituted aromatic heterocyclic group, a substituent having a Hammett's substituent constant σp in the range of −1.0 to 0.0 is preferable, and Hammett's substituent constant σp is Is more preferably in the range of -0.9 to -0.1, more preferably in the range of Hammett's substituent constant σp in the range of -0.9 to -0.2. By having an electron donating group having σp in the above range as a substituent, it is possible to achieve even more preferable absorption characteristics and thermal decomposability as a photoresist compound.
Specific examples of the electron donating group as a substituent of Φ include an alkoxy group, an aryloxy group, an anilino group, a monoalkylamino group, a hydroxy group, a trialkylsilyl group, a trialkylsilyloxy group, an alkyl group, and an alkenyl group. , Aryl group, acylamino group, carbamoylamino group, alkoxycarbonylamino group, 1-aziridinyl group, ferrocenyl group and 3-thienyl group.

In general formula (I), any two or more of R ¹ , R ² , R ³ and Φ may be bonded to each other to form a ring.

  The compound represented by the general formula (I) may be bonded at an arbitrary position to form a multimer, and in this case, each unit may be the same as or different from each other, and polystyrene, polymethacrylate, You may couple | bond with polymer chains, such as polyvinyl alcohol and a cellulose.

  Although the preferable specific example of a compound represented with general formula (I) below is given, this invention is not limited to these.

As the photoresist compound of the present invention, an optimum one can be selected according to the wavelength of light used for pattern exposure.
For example, with respect to the maximum absorption wavelength (λmax), as a general index, when the wavelength of the laser beam used is λnm, the photoresist film by pattern exposure is efficiently decomposed or modified, so that λ ± 150nm In the range of λ ± 100 nm, and more preferably in the range of λ ± 100 nm. For example, when a semiconductor laser beam having a wavelength of 650 nm is used, it can be selected from photoresist compounds having a maximum absorption wavelength in the range of 500 nm to 800 nm, more preferably in the range of 550 nm to 750 nm. Moreover, when using a semiconductor laser beam having a wavelength of 405 nm, it can be selected from photoresist compounds having a maximum absorption wavelength in the range of 255 nm to 555 nm, more preferably in the range of 305 nm to 505 nm.

  Furthermore, the thermal decomposition temperature of the photoresist compound of the present invention is preferably 100 ° C. or higher and 600 ° C. or lower, more preferably 120 ° C. or higher and 550 ° C. or lower, from the viewpoint of sensitivity during pattern exposure with a laser. Most preferably, the temperature is 150 ° C. or more and 500 ° C. or less.

The thermal decomposition temperature in the present invention refers to a value obtained by TG / DTA measurement. Specifically, for example, Seiko Instruments Inc. Using EXSTAR6000 manufactured, the temperature was raised at 10 ° C / min in the range of 30 ° C to 550 ° C under N ₂ stream (flow rate 200ml / min), and the thermal decomposition temperature as the temperature when the mass reduction rate reached 10% Can be requested.

  The photoresist compound of the present invention can be synthesized by a known method, and some of them are commercially available.

[Photoresist solution]
The photoresist solution of the present invention contains the compound for photoresist of the present invention, and preferably contains a solvent. The photoresist liquid of the present invention may contain one type of the compound for photoresists of the present invention, or may contain two or more types. As the solvent, a good solvent for the photoresist compound of the present invention is preferably used. Furthermore, the photoresist solution of the present invention can optionally contain other components in addition to the above components. In order to form a resist film having excellent processability, the content of the photoresist compound in the photoresist solution of the present invention is 50% by mass or more based on the total solid content contained in the photoresist solution. It is preferably 70% by mass or more, more preferably 90% by mass or more. The upper limit is, for example, 100% by mass.

  A photoresist film can be formed by applying the photoresist solution of the present invention onto the surface to be treated and evaporating and removing the solvent. Examples of the coating method include a spray method, a spin coat method, a dip method, a roll coat method, a blade coat method, a doctor roll method, a doctor blade method, a curtain coat method, a slit coat method, and a screen printing method. It is preferable to use a spin coating method in terms of excellent productivity and easy control of the film thickness. As a method for removing the solvent from the applied photoresist solution, a conventionally known method can be used. For example, when applied by a spin coating method, the solvent can be evaporated by increasing the spin speed as it is. At that time, evaporation of the solvent may be promoted by spraying a gas from the nozzle onto the coating surface. Furthermore, as in the conventional photoresist coating process, so-called pre-baking may be performed in which the spin-coated photoresist liquid film is heated (baked). As a method for removing the solvent, a method in which a photoresist solution is applied by a spin coating method, and the solvent is removed by increasing the rotation speed of the spin as it is is particularly preferable. In this case, it is preferable to perform an annealing treatment for further heating. The annealing treatment has an effect of increasing the strength and stability as a photoresist film. The lower limit of the heating temperature is, for example, 55 ° C. or higher, preferably 65 ° C. or higher, more preferably 75 ° C. or higher. The upper limit of the heating temperature is, for example, 200 ° C. or lower, preferably 150 ° C. or lower, more preferably 100 ° C. or lower. is there. The lower limit of the time is, for example, 5 minutes or more, preferably 15 minutes or more, more preferably 30 minutes or more, and the upper limit is, for example, 4 hours or less, preferably 2 hours or less, more preferably 1 hour or less. By annealing under such conditions, the strength and stability of the photoresist film can be increased without reducing the productivity.

  The concentration of the total solid content in the photoresist solution of the present invention is such that the coating property (for example, the film thickness after coating and solvent removal is within a desired range, and the film thickness is uniform over the entire surface to be processed. In addition, even if there is some unevenness on the surface to be processed, the coating film having a uniform thickness is formed following the unevenness, etc. More preferably, it is 0.4 mass% or more and 5 mass% or less, More preferably, it is 0.7 mass% or more and 2 mass% or less.

The solvent that can be used in the photoresist solution of the present invention is preferably one having an appropriate volatility at the time of application in consideration of the application property by a spin coating method, and has the following physical properties in terms of production suitability. Is more preferable.
1. The boiling point is preferably 60 ° C or higher and 300 ° C or lower, more preferably 70 ° C or higher and 250 ° C or lower, and most preferably 80 ° C or higher and 200 ° C or lower.
2. The viscosity is preferably from 0.1 cP to 100 cP, more preferably from 0.5 cP to 50 cP, and most preferably from 1 cP to 10 cP.
3. The flash point is preferably 25 ° C. or higher, more preferably 30 ° C. or higher, and most preferably 35 ° C. or higher.

  Specific examples of the solvent include hydrocarbons (cyclohexane, 1,1-dimethylcyclohexane, etc.), alcohols (butanol, diacetone alcohol, tetrafluoropropanol, etc.), glycol ethers (methyl cellosolve, propylene glycol monomethyl). Ether, propylene glycol monomethyl ether acetate, etc.), esters (butyl acetate, methyl lactate, ethyl lactate, etc.), ketones (methyl ethyl ketone, methyl isobutyl ketone, etc.), nitriles (propionitrile, benzonitrile, etc.), amides ( Dimethylformamide), sulfones (dimethyl sulfoxide, etc.) carboxylic acids (acetic acid, etc.), amines (triethylamine, etc.), halogens (trichloromethane, hydrofluorocar Emissions, etc.), aromatic Shokurui (toluene, xylene, etc.) and the like. Of these, alcohols or glycol ethers are particularly preferred because of their coating properties. The said solvent may be used independently and may mix and use 2 or more types.

Although the photoresist liquid of this invention should just contain the said compound as a solid content at least, you may contain another component as needed. However, it is preferable that the total amount of other components is 1 time or less in terms of mass ratio with respect to the compound.
Examples of other components include a binder, a fading inhibitor, an antioxidant, a UV absorber, a plasticizer, and a lubricant. Examples of binders include natural organic polymer materials such as gelatin, cellulose derivatives, dextran, rosin and rubber; hydrocarbon resins such as polyethylene, polypropylene, polystyrene and polyisobutylene; polyvinyl chloride, polyvinylidene chloride, polychlorinated Vinyl resins such as vinyl / polyvinyl acetate copolymers, acrylic resins such as polymethyl acrylate and polymethyl methacrylate, polyvinyl alcohol, chlorinated polyethylene, epoxy resins, butyral resins, rubber derivatives, phenol / formaldehyde resins, etc. Examples thereof include synthetic organic polymers such as an initial condensate of a thermosetting resin. When adding a binder to the photoresist solution of the present invention, the amount of the binder added is preferably 0.01 to 1 times the mass ratio of the photoresist compound of the present invention, More preferably, the amount is 0.1 to 0.5 times.

Since the photoresist compound of the present invention generally does not decompose or denature under normal indoor lighting environment, a safety light such as a conventional photoresist (for example, ultraviolet light or light having a shorter wavelength than that is cut off). It is not necessary to use under lighting. However, when used under illumination in such a normal indoor environment, various anti-fading agents can be contained in the photoresist solution in order to form a resist film having excellent light resistance.
As the antifading agent, a singlet oxygen quencher is generally used. As the singlet oxygen quencher, those described in publications such as known patent specifications can be used. Specific examples thereof include JP-A Nos. 58-175893, 59-81194, 60-18387, 60-19586, 60-19587, and 60-35054. 60-36190, 60-36191, 60-44554, 60-44555, 60-44389, 60-44390, 60-54892, JP-A-60-47069, JP-A-63-209995, JP-A-4-25492, JP-B-1-38680, JP-A-6-26028, etc., German Patent No. 350399, and Japan Examples include those described in Chemical Society Journal, October 1992, page 1141. The amount of the anti-fading agent such as the singlet oxygen quencher used can be, for example, in the range of 0.1 to 50% by mass with respect to the amount of the photoresist compound of the present invention, It can be in the range of 5-45% by mass, more preferably in the range of 3-40% by mass, particularly preferably in the range of 5-25% by mass.

  As will be described later, according to the photoresist solution of the present invention, an etching mask can be formed without going through a development process. Therefore, a combination component of o-naphthoquinone diazitosulfonic acid ester and novolak resin, which is included as an essential component in a normal photopolymer type resist solution requiring a development process, a combination component of a photoacid generator and an acid-decomposable compound, light The combination component of the base generator and the base decomposable compound, the combination component of the photo radical generator and the addition polysaturated unsaturated compound is not an essential component in the photoresist solution of the present invention, the photoresist solution of the present invention is It is preferable not to contain these components.

  The photoresist solution of the present invention can be obtained by mixing the photoresist compound of the present invention with the above-described components as necessary.

  A photoresist film can be formed by applying the photoresist solution of the present invention to the surface to be processed and removing the solvent, and exposing the photoresist film with a laser beam in a desired pattern. A resist having a desired pattern can be formed. The details of the coating method of the photoresist liquid for forming the resist film are as described above.

  Since the photoresist film of the present invention bears its function, the photoresist film preferably contains the photoresist compound in an amount of 50% by mass or more based on the total mass of the photoresist film. The content is more preferably 70% by mass or more, and still more preferably 90% by mass or more. The upper limit is, for example, 100% by mass. The various components that can be contained in the photoresist film are as described above for the photoresist composition of the present invention.

  In the photoresist solution of the present invention, an embodiment in which the total amount of the solid content is composed of the photoresist compound is an excess photoresist solution after the surface to be processed is provided in the spin coating process (for example, during spin coating). This is particularly preferable in that it is easy to collect and reuse the photoresist solution shaken off from the surface to be processed.

  The photoresist liquid of the present invention can be applied to any application as long as it requires a fine processing. For example, in various processes such as a manufacturing process of a semiconductor device such as an LSI, LED, CCD, or solar cell, a manufacturing process of an FPD such as a liquid crystal, a PDP, or an EL, or a manufacturing process of an optical member such as a lens or a film. It can be used instead of the resist solution. That is, instead of the conventional photoresist solution coating and solvent removal step, pattern exposure step and development step, the photoresist solution coating and solvent removal step and pattern exposure step of the present invention can be used.

  The photoresist liquid of the present invention can also be used in the production of a master for nanoimprinting.

  Furthermore, the photoresist solution of the present invention is used to improve the light extraction efficiency of LEDs by forming fine irregularities on the surface, back surface (for example, sapphire substrate), side surfaces, etc. of LED chips. can do. In general, the material constituting the outermost layer (for example, a current diffusion layer or a transparent electrode) serving as a light extraction port of an LED chip has a refractive index different from that of the resin for the package. While the refractive index is 3 or more, the refractive index of the latter package resin is around 1.5. When light is extracted from such a high refractive index portion to a low refractive index portion, the light is reflected at the interface and the light extraction efficiency is reduced. By doing so, the light extraction efficiency can be improved. Therefore, after forming a layer (for example, a current diffusion layer) that becomes a light extraction port of the LED chip, the photoresist liquid of the present invention is applied to the surface of this layer, and the solvent is removed to form a photoresist film. Then, this photoresist film is subjected to pattern exposure in which only a portion corresponding to a concave portion of a desired fine concavo-convex pattern is irradiated with laser light, followed by etching, and the surface of the extraction port corresponding to the portion irradiated with the above laser light By etching the film to form a concave portion, fine irregularities can be formed at the outlet. Thereafter, the LED chip can be completed through a necessary process (for example, a process of forming an electrode on the surface of the current diffusion layer). The light extraction port of the LED chip thus obtained has fine irregularities on the surface. Since this LED element is packaged into an LED, fine irregularities are formed at the interface between the packaging resin and the light extraction port, so that an LED with less reflection at the interface and high light extraction efficiency is produced. be able to. Thus, when taking out from a portion with a large refractive index to a portion with a small refractive index, the light extraction efficiency can be increased by providing fine irregularities at the interface. The depth h and the diameter d of the concave portion to be formed at the light emitting portion interface may be any size that causes scattering / diffraction of light generated in the light emitting portion, and preferably not less than a quarter of the emission wavelength. It can be designed based on scattering theory.

As described above, when forming fine irregularities on the surface to be processed, a photoresist film is formed on the surface using the photoresist solution of the present invention, and a fine pattern is exposed by laser, and this is used as a mask. Then, fine unevenness corresponding to the fine pattern can be formed on the surface to be processed by RIE or the like. In addition, a mask layer is provided on the surface to be processed, a photoresist film is formed thereon using the photoresist solution of the present invention, this is finely processed by laser, and then fine holes are formed in the mask layer by RIE. Furthermore, it is also possible to etch the surface to be processed deeper with ICP (inductively coupled plasma) through the mask layer in which the fine holes are formed. The etching method using such a mask layer is an advantageous method when the surface to be processed is hard and difficult to be etched like sapphire. The mask layer is preferably an inorganic oxide film or nitride film such as SiO ₂ , TiO ₂ , SiN, or SiON.

  Further, the thickness t of the photoresist film formed using the photoresist solution of the present invention and the diameter d of the recesses are determined by etching of the type of the photoresist compound of the present invention, the material of the surface to be processed, the selection ratio, etc. It can be set according to the process conditions. The optical characteristics during laser recording should also be set in consideration. As a preferred range, the upper limit of the thickness t of the resist layer is a value satisfying t <100d, more preferably a value satisfying t <10d, and the lower limit is preferably a value satisfying t> d / 100, A value satisfying t> d / 10 is more preferable.

[Surface etching method]
Furthermore, the present invention relates to a method for etching a surface to be processed. The etching method of the present invention comprises applying the photoresist solution of the present invention to a surface to be processed to form a photoresist film, pattern exposing the photoresist film, and applying the photoresist film after the pattern exposure Etching at least a part of the processed surface, and etching at least a part of the processed surface in a region corresponding to the exposed part in the pattern exposure.

  In the photoresist film subjected to pattern exposure, pits are formed in the exposed photoresist film at the time of pattern exposure, or a part having a local change in physical properties such as a low durability part is formed. In the etching process, the processing surface corresponding to the pits and / or the low durability portion of the photoresist film is preferentially etched, and the processing surface underneath is also etched to form a recess. In this way, at least a part of the surface to be processed in the region corresponding to the exposed portion in the pattern exposure can be etched to form fine irregularities on the surface to be processed. Further, when the surface to be processed has a plurality of thin layers, at least one of the thin layers can be removed in a pattern. By utilizing this, various semiconductor devices can be manufactured.

  For pattern exposure, a method in which exposure is performed through a photomask using a known stepper can be adopted. However, the laser beam is pulse-modulated, and the modulated laser beam is narrowed down through a lens. Pattern exposure is preferably performed so that the focal point is a photoresist film. As a pattern exposure apparatus for performing such light irradiation, a recording apparatus used for recording information on an optical disk is suitable. However, monochromatic light such as laser light may not be used as long as the light can be condensed to a required size.

  The type of laser light may be any laser such as a gas laser, a solid laser, or a semiconductor laser. However, in order to simplify the optical system, it is preferable to employ a solid laser or a semiconductor laser. The laser light may be continuous light or pulsed light, but it is preferable to employ laser light whose emission interval can be freely changed. An example of such a laser is a semiconductor laser. In addition, when the laser cannot be directly on-off modulated, it is preferable to modulate by an external modulation element.

  A higher laser power is preferable for increasing the processing speed. However, as the laser power is increased, the scanning speed (speed for scanning the coating film with laser light; for example, the rotational speed of the optical disk drive described later) must be increased. Therefore, the upper limit value of the laser power is preferably 100 W in consideration of the upper limit value of the scanning speed, more preferably 10 W, still more preferably 5 W, and most preferably 1 W. The lower limit of the laser power is preferably 0.1 mW, more preferably 0.5 mW, and even more preferably 1 mW.

Further, the laser light is preferably light that has excellent transmission wavelength width and coherency and can be narrowed down to a spot size equivalent to the wavelength. In addition, it is preferable to adopt a strategy generally used in an optical disc as the light pulse irradiation condition. That is, it is preferable to adopt conditions such as recording speed, the peak value of the laser beam to be irradiated, and the pulse width as used in an optical disc.

  The wavelength of the laser light may be any wavelength that can provide a large laser power. For example, 1064 ± 30 nm, 800 ± 50 nm, 670 ± 30 nm, 532 ± 30 nm, and 405 nm are easily obtained laser wavelengths. ± 50 nm, 266 ± 30 nm, and 200 ± 30 nm are preferable. Among these, 780 ± 30 nm, 660 ± 20 nm, or 405 ± 20 nm, which can provide a large output with a semiconductor laser, is preferable. Most preferably, it is 405 ± 10 nm. The maximum absorption wavelength λa of the photoresist compound to be used and the wavelength λw of the laser beam may be either λa ≦ λw or λa ≧ λw. In order to uniformly apply light from the front surface to the back surface of the photoresist film in the thickness direction and to heat the entire surface to form a clean hole, it is preferable that the amount of absorption of the thin film is within a certain range. If there is too much absorption, light will reach only the surface, and if it is too little, light will not turn into heat and efficiency will deteriorate. The upper limit of the extinction coefficient k representing the ease of absorption of the material is suitably 2 or less, preferably 1 or less, particularly preferably 0.5 or less. The lower limit is preferably 0.0005 or more, 0.005 or more, or 0.05 or more. If it is the said relationship, the light absorption amount of the compound for photoresists is appropriate, and a favorable pit or a low durability part can be formed by pattern exposure.

  The thickness of the resist film can be appropriately set within a range of 1 to 10,000 nm, for example. The lower limit of the thickness is preferably 10 nm or more, and more preferably 30 nm or more. The reason is that if the thickness is too thin, it is difficult to obtain an etching effect. Moreover, the upper limit of thickness becomes like this. Preferably it is 1000 nm or less, More preferably, it is 500 nm or less. The reason is that if the thickness is too thick, a large laser power is required, and it becomes difficult to form a deep hole, and further, the processing speed decreases.

  As the light irradiation method, for example, a well-known pit formation method for a write-once optical disc or a write-once optical disc can be applied. Specifically, for example, by detecting the intensity of the reflected light of the laser that changes depending on the pit size and correcting the laser output so that the intensity of the reflected light is constant, a uniform pit is formed. A known running OPC technique (for example, see Japanese Patent No. 3096239) can be applied. In addition, since the resist film of the present invention can function as an etching mask by removing the portion at the time of etching if there is a portion where the physical property has changed to such an extent that it is removed by etching by light irradiation, It is not essential that pits (openings) that can be recognized visually are formed. Also, the size and processing pitch of the pits and physical property changing portions can be controlled by adjusting the optical system. Since the laser light has the highest light intensity near the center and gradually decreases toward the outside, fine pits having a diameter smaller than the spot diameter of the laser light can be formed on the coating film. Further, when it is desired to form a pit larger than the minimum processing shape of the laser beam, a laser spot may be connected.

Below, the specific aspect of the optical system used for a process is demonstrated. However, this invention is not limited to the aspect shown below.
As the light irradiation device, one having the same configuration as a general optical disk drive can be used. As the optical disk drive, for example, one having a configuration described in Japanese Patent Laid-Open No. 2003-203348 can be used. Using such an optical disk drive, if the object to be processed on which the coating film is formed has a disk shape, if the shape is different, it is loaded on the disk drive by pasting it on a dummy optical disk. And a laser beam is irradiated on a coating film with a suitable output. Furthermore, a pulse signal or a continuous signal may be input to the laser light source so that this irradiation pattern matches the processing pattern. Further, by using a focusing technique similar to that of the optical disk drive, for example, an astigmatism method, even if the coating film surface is wavy or warped, it can be easily condensed on the coating film surface. Further, as in the case of recording information on the optical recording disc, the entire coating film can be irradiated with light periodically by moving the optical system in the radial direction while rotating the workpiece.

  As for the light irradiation conditions, for example, the lower limit of the numerical aperture NA of the optical system is preferably 0.4 or more, more preferably 0.5 or more, and still more preferably 0.6 or more. Moreover, it is preferable that the upper limit of numerical aperture NA is 2 or less, More preferably, it is 1 or less, More preferably, it is 0.9 or less. When the numerical aperture is increased, the so-called liquid immersion method in which a liquid is interposed between the objective lens and the photoresist film is advantageous in that the focus adjustment is facilitated. This is because if the numerical aperture NA is too small, fine processing cannot be performed, and if it is too large, the margin for the angle during light irradiation is reduced. The wavelengths of the optical system are, for example, 405 ± 30 nm, 532 ± 30 nm, 650 ± 30 nm, and 780 ± 30 nm. This is because these wavelengths are easy to obtain a large output. A shorter wavelength is preferable because fine processing can be performed.

  The lower limit of the output of the optical system is, for example, 0.1 mW or more, preferably 1 mW or more, more preferably 5 mW or more, and further preferably 20 mW or more. The upper limit of the output of the optical system is, for example, 1000 mW or less, preferably 500 mW or less, more preferably 200 mW or less. This is because if the output is too low, processing takes time, and if it is too high, the durability of the members constituting the optical system becomes low.

  The lower limit of the linear velocity for moving the optical system relative to the coating film surface is, for example, 0.1 m / s or more, preferably 1 m / s or more, more preferably 5 m / s or more, and still more preferably 20 m / s. That's it. The upper limit of the linear velocity is, for example, 500 m / s or less, preferably 200 m / s or less, more preferably 100 m / s or less, and still more preferably 50 m / s or less. If the line speed is too high, it is difficult to increase the processing accuracy, and if it is too slow, it takes time for processing and it is difficult to process into a good shape. As an example of a specific optical processing machine including an optical system, NE0500 manufactured by Pulstec Industrial Co., Ltd. can be used, for example.

  The photoresist film described above can be used as an etching mask without undergoing a development process after pattern exposure. In addition, you may insert the post-baking which performs heat processing as a process after the pattern exposure and before the etching demonstrated below. By performing post-baking, the photoresist film after pattern exposure can be firmly fixed to the surface to be processed, and the function as a mask for subsequent etching can be improved. The lower limit of the post-baking heating temperature is, for example, 55 ° C. or more, preferably 65 ° C. or more, more preferably 75 ° C. or more. The upper temperature limit is, for example, 200 ° C. or less, preferably 150 ° C. or less, more preferably 100 ° C. It is as follows. By performing the heat treatment in such a range, the above-described effect can be obtained without causing a decrease in productivity.

Examples of the etching method include various etching methods such as wet etching and dry etching, and a method corresponding to the physical properties of the surface to be etched may be employed. In order to perform microfabrication, it is preferable to employ RIE (reactive ion etching) in which the etching gas has high straightness and enables fine patterning. In RIE, an object to be processed is placed in an airtight processing chamber, and after a predetermined processing gas is introduced and evacuated to a predetermined reduced pressure atmosphere, for example, a predetermined pressure is applied to an electrode formed in the processing chamber. Plasma is excited by applying high frequency power, and an object to be processed is etched by etchant ions in the plasma. This RIE etching gas can be selected according to the material to be etched.
The photoresist film formed from the photoresist liquid of the present invention is usually removed after etching, but may be left without being removed depending on the application. The removal of the photoresist film can be performed, for example, by a wet removal method using a stripping solution (for example, ethanol).

Although the embodiment in which the photoresist solution of the present invention is used for etching has been described above, the photoresist solution of the present invention can also be used for depositing a desired substance in a desired region on the surface to be processed.
For example, the LED chip is provided with an electrode such as AuZn or AuGe on a part of the surface of the light extraction port (for example, current diffusion layer). In this case, the photoresist liquid of the present invention is applied to the surface of the light extraction port (for example, the surface of the current diffusion layer), the solvent is removed to form a photoresist film, and then laser light is applied to the region where the electrode is to be formed. Irradiate to remove the photoresist film. In this case, the amount of laser light applied to the photoresist film may be sufficient to form a low durability portion on the photoresist film. In that case, the photoresist of the low durability portion is subsequently etched. By removing the film, the photoresist film in the region where the electrode is to be formed can be removed. Thereafter, a material to be an electrode (for example, AuZn or AuGe) is deposited under vacuum, and then the photoresist film is removed, whereby an electrode is formed in a desired region on the surface of the light extraction port.

  As described above, the photoresist compound of the present invention can be used for forming fine irregularities and for producing semiconductor devices. Specific examples include, but are not limited to, various electronic components such as semiconductor elements, magnetic bubble memories, and integrated circuits, light emission of LEDs, fluorescent lamps, organic EL elements, plasma displays, and the like.

  Hereinafter, the present invention will be described by way of examples, but the present invention is not limited to the embodiments shown in the examples.

[Example 1]
(1) Formation of photoresist film 2 g of the compound represented by the general formula (I) (Exemplary Compound (51), thermal decomposition temperature: 258 ° C.) is dissolved in 100 ml of tetrafluoropropanol (TFP) to form disc-shaped silicon. A coating film was formed by spin coating on a substrate (thickness 0.6 mm, outer diameter 120 mm, inner diameter 15 mm). In spin coating, the coating liquid was dispensed on the inner periphery of the substrate at a coating start rotation speed of 500 rpm and a coating end rotation speed of 100 rpm, and the coating film was dried by gradually increasing the rotation speed to 2200 rpm. The formed coating film had a thickness of 100 nm and a maximum absorption wavelength λmax of 377 nm.
The silicon substrate on which the coating film was formed was placed in NEO500 (wavelength: 405 nm, NA: 0.65) manufactured by Pulstec Industrial Co., Ltd., and laser light was irradiated toward the coating film surface. The laser light irradiation conditions were as follows. In the coating film, pits were formed at a pitch of 0.5 μm.
Laser power: 2mW
Line speed: 5m / s

(2) Concavity and convexity formation Each silicon substrate having a resist film on which pits were formed by the above treatment was RIE etched from the coating film forming surface side under the following conditions, and then the coating film was removed using ethanol as a stripping solution. It was visually confirmed that fine unevenness was formed on the surface of the silicon substrate where the coating film was removed. This result shows that the coating film containing exemplary compound (51) functioned as an etching mask.
Etching gas: SF6 + CHF ₃ (1: 1)
Etching depth: 50 nm

[Examples 2 to 7]
When the same treatment as in Example 1 was performed except that the compound represented by the general formula (I) (Exemplary Compound (51)) was replaced with the compound shown in Table 1, the same result as in Example 1 was obtained. It was.

  According to the present invention, fine surface processing can be easily performed.

Claims (7)

A compound for photoresist, which is a compound represented by the following general formula (I):

[In the general formula (I), R ¹ and R ² each independently represent a substituent having a Hammett's substituent constant σp of 0.2 to 0.9, and R ³ represents a hydrogen atom or a monovalent Φ represents a substituted or unsubstituted aryl group or an aromatic heterocyclic group, and any two or more of R ¹ , R ² , R ³ and Φ are bonded to each other to form a ring. It may be. ] The compound for photoresists according to claim 1, wherein in formula (I), Φ represents an aryl group or an aromatic heterocyclic group having a substituent having a Hammett substitution constant σp in the range of -1.0 to 0.0. . The photoresist compound according to claim 1, which has a thermal decomposition temperature of 150 ° C. or more and 500 ° C. or less. The photoresist liquid containing the compound for photoresists of any one of Claims 1-3. The photoresist solution according to claim 4, wherein the photoresist compound contains 50% by mass or more based on the total solid content in the photoresist solution. Applying the photoresist solution according to claim 4 or 5 to a surface to be processed to form a photoresist film;
Pattern exposure to the photoresist film; and
Etching at least a part of the processing surface having the photoresist film after the pattern exposure, and etching at least a part of the processing surface in a region corresponding to the part exposed in the pattern exposure. Process surface etching method. The light used for the pattern exposure is laser light having a wavelength of λ nm, and the maximum absorption wavelength λmax of the photoresist compound contained in the photoresist film is in the range of λ ± 150 nm. Method for etching the surface of the workpiece