JP2004199084A - Method for forming resist pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a practical method for forming a resist pattern by a PCM (portable comfortable mask) method which can be carried out with electron beams and which uses a specified material as an upper layer material having a high absorption wavelength range to be able to give a mask at the time of exposure of a lower layer and hardly producing a mixing region with the lower layer film. <P>SOLUTION: The method includes processes of: forming a lower layer photosensitive material film on a substrate; forming an upper layer photosensitive material film containing a substituted or unsubstituted benzene ring or polycyclic condensed aromatic ring or alicyclic skeleton on the lower layer photosensitive material film; exposing a specified region of the upper layer photosensitive material film to electron beams; dissolving and removing the exposed part or the unexposed part of the upper layer photosensitive material film after exposure with an alkali aqueous solution to develop; and irradiating the entire region with the light of 190 to 260 nm wavelengths while using the upper layer photosensitive material film pattern obtained by the above developing process as a mask, and developing to selectively dissolve and remove the exposed part to transfer the pattern of the upper layer photosensitive material film to the lower layer photosensitive material film. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a method for forming a resist pattern used for fine processing in a manufacturing process of a semiconductor element, a TFT (thin film transistor), an optical disk, and the like.

  2. Description of the Related Art Microfabrication technology using photolithography has been employed in the manufacturing processes of electronic components such as LSIs. That is, first, a resist solution is applied on a substrate or the like to form a resist film, and then the obtained resist film is exposed to pattern light, and then subjected to processing such as alkali development to form a resist pattern. Form. Subsequently, the surface of the exposed substrate or the like is dry-etched using the resist pattern as an etching-resistant mask to form fine-width lines and openings, and finally, the resist is removed by ashing.

  Therefore, the resist used here is generally required to have high dry etching resistance. From such a viewpoint, resists containing an aromatic compound have been widely used so far, and specifically, a large number of resists using an alkali-soluble novolak resin or the like as a base resin have been developed.

  On the other hand, with the high-density integration of LSI and the like, the above-mentioned fine processing technology has recently reached the order of the sub-half micron, and such fine processing is expected to become more remarkable in the future. For this reason, the wavelength of the light source in photolithography has been shortened, and an attempt is currently being made to form a fine resist pattern using ArF excimer laser light having a wavelength of 193 nm or fifth harmonic light of a YAG laser having a wavelength of 218 nm.

  However, a resist using a novolak resin as a base resin, which has been generally used until now, tends to have a large light absorption at the benzene nucleus of the novolak resin with respect to the short-wavelength light as described above. Therefore, when trying to form a resist pattern, it is difficult to sufficiently reach light to the substrate side of the resist film during exposure, and as a result, it is difficult to form a pattern having a good pattern shape with high sensitivity and high precision Met.

  Incidentally, a pattern forming method called a PCM (Portable Comfortable Mask) method was described in Proc. SPIE. 174,114. J. Shown by Lin. This is a pattern forming method in which an upper layer resist pattern is formed, and the lower layer is collectively exposed using the resist pattern as a mask. As performed by this PCM method, A.I. W. 1986, by McCullough et al., Proc. SPIE. 631, 316 report as follows. In this method, PMGI (polydimethylglutarimide) is used as a lower layer material, and a pattern is formed by batch exposure using a pattern formed of novolak-naphthoquinonediazide in an upper layer as a mask.

  The PCM method as described above has an advantage in that since the pattern is transferred and formed even in the step of exposing and developing the lower layer, dust or the like called scum which is observed in the transfer and formation of the pattern by etching does not occur. . Since then, various PCM methods have been proposed. However, in the conventional PCM method, the lower layer photosensitive material is often impractical in dry etching resistance as compared with a normal phenol resin, and is not practical. A. As described above. W. In the example of McCullough et al., A novolak-naphthoquinonediazide material used in lithography using a mercury lamp is used as the upper photosensitive material, and a lithography using a KrF excimer laser beam called PMGI having a shorter wavelength than the mercury lamp is used as the lower photosensitive material. The materials used in are adopted. For this reason, the wavelength of exposure light for forming an upper layer pattern is long, and there is no advantage in forming an optically fine pattern. Further, there is a problem that it is difficult to form a fine pattern due to a problem such as mixing between layers when actually laminating the photosensitive layers.

  As described above, a resist using a novolak resin as a base resin has high dry etching resistance and can be alkali-developed, but has insufficient transparency with respect to short-wavelength light, so that a resist of ArF excimer laser light or YAG laser cannot be used. There is a strong demand for the development of a resist suitable for photolithography using harmonic light. In view of these points, a resist containing an alicyclic compound instead of an aromatic compound has recently attracted attention. For example, Japanese Patent Application Laid-Open No. 4-39665 discloses a resist having dry etching resistance and transparency to short wavelength light. A resist using a polymer having an adamantane skeleton as a base resin has been proposed as a good resist. Here, there is also shown an example in which a compound having an adamantane skeleton is copolymerized with an acrylic compound having a carboxylic acid group to impart alkali solubility to the polymer, and a resist pattern is formed by alkali development.

  However, in the case of forming a resist pattern by alkali development with respect to a resist containing an alicyclic compound in this way, alkali solubility differs greatly between an alicyclic structure such as an adamantane skeleton and a carboxylic acid group. Problems arise. For example, during development, dissolution / removal of a predetermined region of the resist film becomes non-uniform, resulting in a decrease in resolution. On the other hand, partial dissolution occurs even in a region where the resist film is to remain, thereby causing cracks and surface roughness. Cause. In addition, the alkaline solution may penetrate into the interface between the resist film and the substrate, and the resist pattern may be peeled off, so that sufficient adhesion cannot be obtained. Further, the phase separation between a portion having an alicyclic structure and a carboxylic acid portion in the polymer is apt to proceed, and it is difficult to prepare a uniform resist solution, and its coatability is not sufficient.

  As a highly sensitive resist, a chemically amplified resist utilizing the catalytic action of an acid has been developed. However, this chemically amplified resist is easily affected by the time from exposure to PEB. In particular, the shape of the resist pattern obtained due to the effect of amines contained in the air deteriorates, and in some cases, peeling off from the substrate may occur.

  As described above, in the conventional PCM method, the upper layer photosensitive material employs a material used in lithography having a longer wavelength than the lower layer photosensitive material, and there is no advantage in forming an optically fine pattern. Did not exist.

  Therefore, the present invention provides a PCM using a specific material as an upper layer material which can be performed by an electron beam, has a high absorption wavelength band which can be used as a mask at the time of exposure of the lower layer, and hardly forms a mixing or the like with the lower layer film. It is an object of the present invention to provide a practical method of forming a resist pattern by a method.

  The method for forming a resist pattern according to one embodiment of the present invention includes a step of forming a lower photosensitive material film on a substrate, and a step of forming a substituted or unsubstituted benzene ring or a polycyclic fused aromatic ring on the lower photosensitive material film. Or a step of forming an upper photosensitive material film containing an alicyclic skeleton, a step of irradiating a predetermined region of the upper photosensitive material film with an electron beam and exposing the same, and an upper photosensitive material film after the exposure. Dissolving and removing the exposed or unexposed portion of the film with an aqueous alkali solution and developing; and using the upper photosensitive material film pattern obtained after the developing process as a mask, collectively irradiating light having a wavelength of 190 to 260 nm, Transferring the upper photosensitive material film pattern to the lower photosensitive material film by performing a treatment to selectively dissolve and remove the exposed portions.

  According to the present invention, a specific material which can be performed by an electron beam, has a high absorption wavelength band which can be used as a mask at the time of exposure of the lower layer, and hardly forms mixing with the lower layer film is used as the upper layer material. A practical resist pattern forming method by the PCM method is provided.

  Hereinafter, the present invention will be described in detail. In the present invention, as the alkali-soluble resin, an alkali-soluble resin composed of a copolymer such as acrylic acid and methacrylic acid can be used. More specifically, a copolymer composed of menthyl methacrylate, methyl methacrylate and methacrylic acid; a copolymer composed of vinyl naphthalene, menthyl acrylate, methyl methacrylate, and methacrylic acid, and the like can be mentioned.

  In the present invention, since the alkali-soluble resin has an alicyclic structure or a condensed polycyclic structure, in addition to the advantage of good transparency at 193 nm, it is possible to impart high dry etching resistance to the obtained resist pattern. Can be. Examples of the alicyclic structure include a cyclic cyclo compound and a cyclic bicyclo compound represented by the general formula Cn H2n (n is an integer of 3 or more), and condensed rings thereof. Specifically, cyclobutane ring, cyclopentane ring, cyclohexane ring, cycloheptane ring and those in which a bridging hydrocarbon is introduced, spiroheptane, spiro ring such as spirooctane, norbornyl ring, adamantyl ring, bornene ring, Menthyl ring, terpene ring such as menthane ring, tujang, sabinen, tsujong, karan, karen, pinan, norpinan, bournan, fencan, tricyclene, cholesteric ring and other steroid skeleton, bile acids, digitaloids, camphor ring, isophane ring, Examples include a sesquiterpene ring, a Sandton ring, a diterpene ring, a triterpene ring, and steroid saponins. In addition, as the alicyclic skeleton, a compound having a substituted or unsubstituted menthyl group is particularly preferable from the viewpoint of being naturally occurring and being environmentally friendly.

  On the other hand, examples having a condensed polycyclic structure include the following. For example, indene, indane, benzobulden, 1-indanone, 2-indanone, 1,3-indadione, ninhydrin, naphthalene, methylnaphthalene, ethylnaphthalene, dimethylnaphthalene, cadallene, vinylnaphthalene, 1,2-dihydronaphthalene, 1,4 Dihydronaphthalene, 1,2,3,4-tetrahydronaphthalenetetralin, 1,2,3,4,5,6,7,8-octahydronaphthalene, cis-decalin, trans-decalin, fluoronaphthalene, chloronaphthalene, Bromonaphthalene, iodonaphthalene, dichloronaphthalene, (chloromethyl) naphthalene, 1-naphthol, 2-naphthol, naphthalene diol, 1,2,3,4-tetrahydro-1-naphthol, 1,2,3,4-tetrahydro- 2-naft 5,6,7,8-tetrahydro-1-naphthol, 5,6,7,8-tetrahydro-2-naphthol, decahydro-1-naphthol, decahydro-2-naphthol, chloronaphthol, nitronaphthol, aminonaphthol , Methoxynaphthalene, ethoxynaphthalene, naphthyl ether, naphthyl acetate, naphthaldehyde, naphthalenedicarbaldehyde, hydroxynaphthaldehyde, dinaphthyl ketone, 1 (2H) -naphthalene, α-tetralone, β-tetralone, α-decalone, β- Decalone, 1,2-naphthoquinone, 1,4-naphthoquinone, 2,6-naphthoquinone, 2-methyl-1,4-naphthoquinone, 5-hydroxy-1,4-naphthoquinone, isonaphthazarin, naphthoic acid, 1-naphthol-4 Carboxylic acids, naphthalic acids, naphthalic acids Phthalic anhydride, 1-naphthylacetic acid, thionaphthol, N, N-dimethylnaphthylamine, naphthonitrile, nitronaphthalene, pentalene, azulene, heptalene, fluorene, 9-phenylfluorene, nitrofluorene, 9-fluorenol, fluorenone, anthracene, Methylanthracene, dimethylanthracene, 9,10-dihydroanthracene, anthrol, anthranol, hydroanthranol, dihydroxyanthracene, anthraganol, 1 (4H) -anthracenone, anthrone, anthralobine, chrysarobin, oxantrone, anthracene carboxylic acid, Anthramine, nitroanthracene, anthracenequinone, anthraquinone, methylanthraquinone, hydroxyanthraquinone, phenanthrene, Enanthrol, phenanthrene hydroquinone, phenanthraquinone, biphenylene, s-indacene, as-indacene, phenalene, tetracene, chrysene, 5,6-chrysquinone, pyrene, 1,6-pyrenequinone, triphenylene, benzo [α] anthracene, benzo [Α] anthracene-7,12-quinone, benzantrone, aceanthrylene, acephenanthrylene, acephenanthrene, 17H-cyclopenta [α] -phenanthrene, fluoranthene, preiaden, pentacene, pentaphene, picene, pyrylene, dibenzo [a , J] anthracene, benzo [α] pyrene, coronene, pyranthrene and pyranthrone. The absorption bands of these fused polycyclic skeletons also generally shift from the absorption band of the benzene nucleus, and do not have high absorption in a short wavelength region. Therefore, a photosensitive material capable of forming a resist pattern having dry etching resistance by including these skeletons in the alkali-soluble acrylic resin is obtained.

  Further, the photosensitive material used in the present invention can also be used for evaluating optical characteristics such as an ArF excimer laser. Therefore, when the obtained resist pattern is not used as an etching mask, the alicyclic skeleton, naphthalene skeleton, and anthracene skeleton need not be contained in the alkali-soluble resin.

  When the alkali-soluble resin in the present invention contains an alicyclic skeleton, such a polymer is, for example, a polymerizable compound having an alicyclic structure having an acidic substituent introduced therein and a polymerizable double bond in a molecule. It can be easily obtained by polymerizing by radical polymerization, cationic polymerization, anionic polymerization or the like, or by polymerizing in the presence of a Ziegler-Natta catalyst. Generally, a polymerizable compound having an alicyclic structure and a polymerizable double bond in a molecule can be converted into a high molecular weight polymer by using the latter catalyst. However, in the present invention, even if it is a low molecular weight polymer, there is no problem as long as it can form a film, so it is polymerized using a simple method such as radical polymerization and used in a mixed state of a low molecular weight compound and a high molecular weight compound. May be.

Further, at this time, from the viewpoint of adjusting the alkali solubility of the polymer and improving the adhesion between the resist film and the substrate, acrylic acid, maleic anhydride and their ester-substituted products, vinyl phenol, vinyl naphthol, hydroxyethyl methacrylate, SO ₂ etc. Is preferably copolymerized with Further, a compound obtained by protecting the alkali-soluble group of these alkali-soluble compounds with an acid-decomposable group having an ability to inhibit dissolution in an alkali solution may be copolymerized. However, in consideration of the transparency of the resist to short-wavelength light, it is preferable to copolymerize with a compound such as a benzene nucleus that does not have a molecular skeleton having a large light absorption in a short wavelength region, and specifically, a light having a wavelength of 193 nm. Is preferably 4 or less, more preferably 2 or less per μm. However, when the photosensitive material of the present invention is used as an upper resist on a substrate having an intermediate layer, the film thickness can be reduced, so that the absorbance as described above may be as large as about 8 per μm.

  However, here, the copolymerization ratio of the alkali-soluble compound such as acrylic acid is preferably in the range of 1 to 50%, more preferably 10 to 50% in the copolymer. If the amount is less than 1%, the alkali solubility of the polymer may be insufficient. On the other hand, if the amount exceeds 50%, uneven dissolution may occur, and a resist pattern may not be easily formed.

  The average molecular weight of the above-mentioned polymer is preferably set in the range of 500 to 500,000, more preferably 5,000 to 15,000. If the average molecular weight of the polymer is less than 500, it is disadvantageous in forming a resist film having sufficient mechanical strength, and if it exceeds 500,000, a resist pattern having good resolution can be formed. It becomes difficult to do so. These compounds are usually mixtures containing components having various molecular weights, but in the present invention, even compounds having relatively low molecular weights are effective. For example, even when a large amount is localized at a molecular weight of 500 to 1,000, uneven dissolution can be suppressed. Further, in this case, even if many monomers remain in the resin, it hardly deteriorates the solubility characteristics in an alkali developing solution and the dry etching resistance of the obtained resist pattern.

On the other hand, examples of the diazo compound as another component of the photosensitive material of the present invention include a diazo compound represented by the following general formula (1) and p-quinonediazides such as β-naphthylamide of p-benzoquinonesulfonic acid. P-iminoquinonediazides described in British Patent No. 723 382, organic solvent-soluble condensation products of diazonium salts and formaldehyde described in British Patent No. 1110017, p-diazodiphenylamine salts And aromatic diazonium salts such as co-condensation products of 4,4-bismethoxymethyldiphenyl ether and formaldehyde, and copolymerization products of other aromatic products with formaldehyde, and British Patent No. 745886 Aromatic azides such as the azide compounds described in It is possible.

In the general formula (1), R ¹ and R ² may be the same or different and each represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group, Si, And a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms and a substituted or unsubstituted aryl group containing Si.

  Among the diazo compounds described above, as a positive-type photosensitizer, o-quinonediazides such as aromatic esters or amides of o-naphthoquinonediazidesulfonic acid or o-naphthoquinonediazidecarboxylic acid are particularly environmentally friendly and heat-resistant. It is preferably used from the viewpoint. Among them, naphthoquinone diadsulfonic acid esters of polyhydroxybenzophenone are more preferable, and specifically, 1,2-naphthoquinonediazidosulfonic acid esters of 2,3,4-trihydroxybenzophenone and 2,3,4,4 Most preferred are 1,2-naphthoquinonediazidosulfonic acid esters of 4'-tetrahydroxybenzophenone.

  The latter (1,2,3-naphthoquinonediazidesulfonic acid esters of 2,3,4,4'-tetrahydroxybenzophenone) of the two preferable photosensitive agents described above are useful for improving the heat resistance of the resist. preferable. In these photosensitizers, the esterification rate of 2,3,4,4'-tetrahydroxybenzophenone by 1,2-naphthoquinonediazidosulfonic acid may be 40 to 100% of the total number of hydroxyl groups in the compound. desirable. This is because if the esterification ratio is less than 40%, the resolution may be reduced.

  For example, the number of introduced naphthoquinonediazides indicates an average of 1.6 to 4 per molecule of 2,3,4,4'-tetrahydroxybenzophenone, and generally, the number of introduced 1,2,3,4 Is a mixture of tetrahydroxybenzophenones having the formula:

  In the photosensitive material of the present invention, the amount of the diazo compound as described above is preferably 20 to 60 wt%, more preferably 30 to 50 wt%, based on the alkali-soluble resin. If the amount is less than 20% by weight, the effect of adding the diazo compound cannot be sufficiently obtained, while if the amount exceeds 60% by weight, transparency to ArF excimer laser light, which is a property of the alkali-soluble resin, may be impaired. Because there is.

  The diazo compound may be introduced into a side chain of the alkali-soluble resin. In this case, the alkali-soluble resin preferably has an alicyclic skeleton for the above-described reason. As described above, even when the diazo compound is contained in the alkali-soluble resin, the ratio is preferably 20 to 60% by weight, and more preferably 30 to 50% by weight.

  The photosensitive material of the present invention can be prepared by dissolving an alkali-soluble resin and a diazo compound or an alkali-soluble resin having a diazo compound in a side chain in a predetermined solvent.

  Examples of the solvent used herein include, for example, ketone solvents such as cyclohexanone, acetone, methyl ethyl ketone and methyl isobutyl ketone; cellosolve solvents such as methyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate; ethyl acetate, butyl acetate; Ester solvents such as isoamyl acetate and γ-butyrolactone; glycol solvents such as propylene glycol monomethyl ether acetate; and nitrogen-containing solvents such as dimethyl sulfoxide, hexamethylphosphoric triamide dimethylformamide and N-methylpyrrolidone. Further, a mixed solvent to which dimethylsulfoxide, dimethylformaldehyde, N-methylpyrrolidinone and the like are added for improving the solubility can be used. Further, propionic acid derivatives such as methyl methyl propionate, lactate esters such as ethyl lactate, PGMEA (propylene glycol monoethyl acetate), and the like have low toxicity and can be preferably used. In the present invention, such a solvent can be used alone or in combination of two or more. Further, isopropyl alcohol, ethyl alcohol, methyl alcohol, butyl alcohol, n-butyl alcohol, s-butyl alcohol, t- An aliphatic solvent such as butyl alcohol and isobutyl alcohol and an aromatic solvent such as toluene and xylene may be contained.

  A process for forming a pattern using the photosensitive material of the present invention prepared as described above will be described. First, a solution of a photosensitive material dissolved in an organic solvent as described above is applied to a predetermined substrate by a spin coating method, a dipping method, or the like, and then dried at 150 ° C. or less, preferably at 70 to 120 ° C. Form a film.

  The substrate used herein may be, for example, a silicon wafer, a silicon wafer having various insulating films, electrodes, wirings, etc. formed on its surface, a blank mask, a III-V group compound semiconductor wafer such as GaAs or AlGaAs, chromium or chromium oxide. An evaporation mask, an aluminum evaporation substrate, an IBPSG coated substrate, a PSG coated substrate, an SOG coated substrate, a carbon film sputtered substrate, or the like can be used.

  Furthermore, after forming an intermediate layer made of polysilane, polysilicon or the like on these substrates with a thickness of about 0.5 to 5 μm, the photosensitive material of the present invention can be applied and used as an upper layer resist.

  The thickness of the resist film formed on the substrate after the evaporation of the solvent varies depending on the application, but is usually preferably in the range of 0.05 to 15 μm. Outside of this range, the sensitivity may be significantly reduced or the resolution may be reduced.

Next, the resist film formed on the substrate is exposed to actinic radiation through a predetermined mask pattern according to a desired pattern, or the resist film is exposed by directly scanning the resist film surface with actinic radiation. As described above, the photosensitive material of the present invention has excellent transparency over a wide wavelength range including short-wavelength light, and therefore, the actinic rays used here are ultraviolet rays, X-rays, and low-pressure mercury lamps. i-line light, h-line, g-line, a xenon lamp light, KrF and ArF, deep UV light or synchrotron orbital Raj instantiation of excimer laser light such as F ₂ (SOR), electron beam (EB), gamma-rays, ion beams Although the light-sensitive material of the present invention is particularly effective for short-wavelength light such as an excimer laser light of ArF. The exposed resist film may be baked at about 100 ° C.

  Next, the resist film is developed by an immersion method, a spray method, or the like, and the exposed or unexposed portion of the resist film is selectively dissolved and removed in an alkaline solution to form a desired pattern. At this time, specific examples of the alkaline solution include an aqueous solution of an organic alkali such as an aqueous solution of tetramethylammonium hydroxide and choline, an aqueous solution of an inorganic alkali such as potassium hydroxide and sodium hydroxide, and an alcohol and a surfactant added thereto. Solution. Here, the concentration of the alkaline solution is preferably 15 wt% or less from the viewpoint of ensuring a sufficient dissolution rate difference between the exposed part and the unexposed part.

  The substrate and the resist pattern after the development may be subjected to a rinsing process using water or the like. The photosensitive material of the present invention contains an alkali-soluble resin and a diazo compound, and has good transparency to ArF excimer laser light. Therefore, a resist pattern can be formed with high sensitivity and high accuracy.

  Therefore, the resist pattern formed using the photosensitive material of the present invention having excellent transparency has extremely good resolution, and furthermore, the obtained resist pattern and the adhesion between the substrate and the substrate are high. Peeling does not occur at all. Therefore, for example, an ultrafine pattern of quarter micron or less such as an exposed substrate can be faithfully transferred by dry etching using a resist pattern formed using the photosensitive material of the present invention as an etching mask.

  When an alkali-soluble resin containing an alicyclic skeleton or a condensed polycyclic skeleton is blended as a component of the photosensitive material of the present invention, even if one of the carbon-carbon bonds is broken in the obtained resist pattern. The other bond remains. Therefore, such a resist pattern has high dry etching resistance.

  In the pattern forming process using the photosensitive material of the present invention, any other steps other than the steps described above may be added without any problem, for example, a flattening layer forming step as a base of a resist film, a resist film A pretreatment step for improving the adhesion to the base, a rinsing step of removing the resist film with water after development, and a re-irradiation step of ultraviolet rays before dry etching can be appropriately performed.

  The pattern forming method of the present invention can be preferably applied to a multilayer resist process. This process is described below. When the pattern forming method of the present invention is applied to a multilayer process, for example, an upper layer exposed by an ArF excimer laser beam as a first actinic radiation and a second actinic radiation having a wavelength range of 200 to 260 nm are used. A lower layer exposed by light can be formed. Alternatively, an upper layer exposed by a low-acceleration electron beam and a lower layer exposed by light in a wavelength range of 190 to 260 nm may be formed.

  In the former, the photosensitive material used for the upper layer is preferably a photosensitive material having a high transparency at 193 nm and containing a condensed polycyclic skeleton containing a naphthyl group having a high absorption at around 220 nm. In this case, a resist such as a phenolic resin represented by chemical formulas (P-1) to (P-4) having good transparency in a wavelength range of 200 to 260 nm and high dry etching resistance is used for the lower layer. Is preferred.

  On the other hand, as the photosensitive material used for the upper layer in the latter, a substituted or unsubstituted polycyclic condensed aromatic ring or a benzene ring having an absorption in a wavelength range of 190 to 260 nm, which can be exposed and developed with low acceleration electron beam with high sensitivity. The photosensitive material used for the lower layer is preferably a material which is exposed to light having a wavelength of 190 to 260 nm and has high dry etching resistance. When the upper layer has a polycyclic fused aromatic ring having an absorption at around 220 nm, the lower layer may be a phenolic resin represented by the following chemical formulas (P-1) to (P-4). When the upper layer has a benzene ring having absorption at around 193 nm, the lower layer is preferably made of an acrylic resin having an alicyclic skeleton.

Here, examples of the polycyclic fused aromatic ring include, among fused polycyclic skeletons, substituted or unsubstituted naphthalene and anthracene. Examples of those having a benzene ring include phenol resins and novolak resins.

  Here, in general, if the lower layer has sufficient dry etching resistance, the upper layer is not necessary, and the upper layer only needs to have an absorbance that can serve as a mask when exposing the lower layer. The thickness of the upper layer only needs to satisfy this condition. Therefore, since the film thickness can be reduced and a high sensitivity is not required, a non-chemically amplified resist is preferably used in addition to the chemically amplified resist.

  In the case where the upper and lower photosensitive material layers are formed, there is often a problem of mixing in which solvents are mixed between the layers. When forming the layer, one of the solutions is to form a layer called a barrier coat, which does not cause mixing with any of the upper layer and the lower layer, between the photosensitive materials of the upper layer and the lower layer. However, it is preferable not to include such a barrier coat layer from the viewpoint of shortening the process and reducing the material.

  In the pattern forming method of the present invention, the use of a material that does not easily cause the above-described mixing has very little effect. Furthermore, in order to prevent mixing, a material that is difficult to dissolve is generally used for the lower layer. For example, when the upper layer is exposed by an ArF excimer laser, a resist for an ArF excimer laser using a xylene solvent can be used for the polyhydroxystyrene-based lower resist for a KrF excimer laser. When a resist for a chemically amplified ArF excimer laser using a xylene solvent is used, a nonionic photoacid generator such as naphthalidyl triflate is preferably used as the acid generator. Also, a quinonediazide compound having a high introduction rate is suitably used as a photosensitizer and a photoacid generator.

  Further, a light absorbing compound such as novolak or naphthol novolak, as described in Japanese Patent Application No. 8-222230, may be contained in the upper layer ArF excimer laser resist to such an extent that the transparency at 193 nm is not remarkably reduced. Thereby, high absorbance can be provided in the wavelength range of 210 to 260 nm. This novolak or naphthol novolak also acts as a dissolution inhibitor.

  On the other hand, when exposing the upper layer with an electron beam, a low acceleration electron beam of 10 keV or less is preferable from the viewpoint of resist sensitivity in pattern formation. As the electron beam resist material used in the present invention, a material made of novolak or polystyrene resin and having a high absorbance at 193 nm is preferably used.

  Hereinafter, the present invention will be described in more detail with reference to Synthesis Examples and Examples.

(Synthesis example 1)
<Synthesis of alkali-soluble acrylic resin having alicyclic structure in side chain>
Mentyl methacrylate, methyl methacrylate, and methacrylic acid were mixed in a total of 6.0 g, each of 33 mol%, 29 mol%, and 38 mol%, in 20 g of tetrahydrofuran (THF). Subsequently, 0.73 g of azoisobutylnitrile (AIBN) was added to the obtained solution, and the mixture was reacted by heating at 60 ° C. for 35 hours with stirring, and then the reaction solution was dropped into n-hexane. Thereafter, the precipitate was filtered and dried to obtain a copolymer having a weight average molecular weight (in terms of styrene) of about 10,000.

(Synthesis example 2)
<Synthesis of alkali-soluble acrylic resin having alicyclic structure and diazo compound in side chain>
Equimolar amounts of hydroxyethyl methacrylate and 1,2-naphthoquinonediazide-4-sulfonic acid chloride were dissolved in dioxane to obtain a 10 wt% dioxane solution. Subsequently, while maintaining this solution at 20 ° C., triethylamine in an amount equivalent to 1.2 equivalents of 1,2-naphthoquinonediazide-4-sulfonic acid chloride was slowly dropped into this dioxane solution to precipitate a salt precipitated. It was separated by filtration and poured into a large amount of a 0.2% oxalic acid solution. The precipitate was filtered, washed with ion-exchanged water, and dried under vacuum to obtain hydroxyethyl methacrylate naphthoquinonediazide sulfonate.

  Next, a total of 6.0 g each of 33 mol%, 29 mol%, and 38 mol% of menthyl methacrylate, hydroxyethyl methacrylate naphthoquinonediazide sulfonic acid ester, and methacrylic acid were mixed with 20 g of tetrahydrofuran (THF). Subsequently, 0.73 g of azoisobutylnitrile (AIBN) was added to the obtained solution, and the mixture was heated at 60 ° C. for 35 hours with stirring to cause a reaction. Then, the reaction solution was dropped into n-hexane. Thereafter, the precipitate was filtered and dried to obtain a copolymer having a weight average molecular weight (in terms of styrene) of about 10,000.

(Synthesis example 3)
<Synthesis of alkali-soluble acrylic resin having condensed polycyclic structure in side chain>
A total of 6.0 g of 30 mol%, 30 mol%, and 40 mol% of vinylnaphthalene, methyl methacrylate, and methacrylic acid were mixed with 20 g of tetrahydrofuran (THF). Subsequently, 0.60 g of azobisisobutyronitrile (AIBN) was added to the obtained solution, and the mixture was reacted by heating at 60 ° C. for 35 hours with stirring. Thereafter, the reaction solution was dropped into n-hexane, and the precipitate was filtered and dried to obtain a copolymer having a weight average molecular weight (in terms of styrene) of about 7,000.

(Synthesis example 4)
<Synthesis of alkali-soluble acrylic resin having alicyclic structure and condensed polycyclic structure in side chain>
Vinyl naphthalene, menthyl methacrylate, methyl methacrylate, and methacrylic acid were mixed in 20 g of tetrahydrofuran (THF) in total of 6.0 g each of 15 mol%, 20 mol%, 30 mol%, and 35 mol%. Subsequently, 0.60 g of azoisobutyronitrile (AIBN) was added to the obtained solution, and the mixture was reacted by heating at 60 ° C. for 35 hours with stirring. Thereafter, the reaction solution was dropped into n-hexane, and the precipitate was filtered and dried to obtain a copolymer having a weight average molecular weight (in terms of styrene) of about 7,000.

(Synthesis example 5)
<Synthesis of chemically amplified acrylic resin having alicyclic structure and condensed polycyclic structure in side chain>
Vinyl naphthalene, menthyl acrylate, tetrahydropyranyl methacrylate, and methacrylic acid were mixed with 26.2 mol%, 19.4 mol%, 21.6 mol%, 32.7 mol%, respectively, 9.43 g in total, in 20 g of tetrahydrofuran (THF). Subsequently, 1.6 g of azoisobutyronitrile (AIBN) was added to the obtained solution, and reacted by heating at 60 ° C. for 40 hours with stirring. Thereafter, the reaction solution was dropped into n-hexane, and the precipitate was filtered and dried to obtain a copolymer having a weight average molecular weight (styrene conversion) of about 6,000.

(Synthesis example 6)
<Solution inhibitor: Synthesis of 1-adamantylcarbonyl-2,2′-ditert-butoxycarbonylethane>
0.02 mol of di-tert-butyl malonate was dissolved in THF, and gradually added at 0 ° C. to a solution in which 0.02 mol of sodium hydride was dispersed. After the completion of hydrogen generation, the reaction system was brought to room temperature, and a THF solution of adamantyl (bromomethyl) ketone (0.02 mol) was introduced. Thereafter, the reaction was performed at room temperature for 5 hours. Next, the reaction solution was poured into a large amount of ice water, and the reaction solution was extracted with ether. The oil layer was washed once with an aqueous oxalic acid solution and subsequently twice with water. Finally, it was dried and concentrated to obtain 1-adamantylcarbonyl-2,2'-ditert-butoxycarbonylethane (AdTB).

(Synthesis example 7)
<Synthesis of dissolution inhibitor>
Naphthol was condensed with glyoxylic acid to obtain a novolak oligomer. 10 g of the novolak oligomer was dissolved in 50 ml of 3,4-dihydropyran and stirred for 48 hours in the presence of a catalytic amount of hydrochloric acid. Thereafter, a lump of sodium hydroxide was added to the solution, and the mixture was stirred for a while. The residue was filtered off, the oil layer was concentrated and dried under reduced pressure, further dissolved in ethyl acetate, and washed twice with a 5% oxalic acid aqueous solution. Next, this was separated, dried over anhydrous sodium sulfate, and concentrated to dryness to obtain a pyranylated naphthol novolak (NV4THP).

(Synthesis example 8)
<Synthesis of photosensitizer>
After dissolving 0.1 g of α-naphthol in THF, 0.1 mol of 1,2-naphthoquinonediazide-4-sulfonyl chloride was added to the THF solution. While stirring this mixture at 0 ° C., 0.1 mol of triethylamine was gradually dropped therein. The precipitated salt was separated by filtration, the reaction solution was concentrated to dryness, and then recrystallized using ethanol-hexane to obtain a naphthoquinonediazide compound of naphthol (NPNQ).

(Reference Example 1)
To the polymer obtained in Synthesis Example 1, 40% by weight of naphthoquinonediazide as a diazo compound was added to obtain a 8% by weight cyclohexanone solution. This solution was filtered through a 0.2 μm membrane filter, applied to a Si wafer by spin coating, and prebaked at 100 ° C. for 90 seconds to form a 0.2 μm thick resist film.

The resist film is exposed by irradiating it with ArF excimer laser light (NA = 0.55) having a wavelength of 193 nm. Subsequently, the exposed resist film is exposed to tetramethylammonium hydroxide (TMAH) as an alkali developing solution. ) Was developed with a 2.38% aqueous alkaline solution. As a result, a 0.15 μm line-and-space pattern could be resolved with a DOSE amount of 130 mJ / cm ² . The obtained pattern had good adhesion to the substrate, and no peeling of the pattern was observed.

(Reference Example 2)
To the polymer obtained in Synthesis Example 1, 45 wt% of a diazo compound of Meldrum's acid was added to obtain an 8 wt% ethyl lactate solution. This solution was filtered through a 0.2 μm membrane filter, applied on a Si wafer by spin coating, and prebaked at 120 ° C. for 90 seconds to form a 0.2 μm thick resist film.

The resist film is exposed by irradiating it with ArF excimer laser light (NA = 0.55) having a wavelength of 193 nm. Subsequently, the exposed resist film is treated with 2.38% alkali of TMAH as an alkali developing solution. Developed in aqueous solution. As a result, a 0.15 μm line-and-space pattern could be resolved with a DOSE amount of 120 mJ / cm ² . The obtained pattern had good adhesion to the substrate, and no peeling of the pattern was observed.

(Reference Example 3)
To the polymer obtained in Synthesis Example 1, 40% by weight of naphthoquinonediazide as a diazo compound was added to obtain a 8% by weight cyclohexanone solution. This solution was filtered through a 0.2 μm membrane filter, applied to a Si wafer by spin coating, and prebaked at 100 ° C. for 90 seconds to form a 0.5 μm thick resist film.

The resist film was exposed to an electron beam, and then the exposed resist film was developed with a 2.38% aqueous solution of TMAH as an alkaline developer. As a result, a 0.15 μm line-and-space pattern could be resolved with an acceleration voltage of 50 keV and a DOSE amount of 30 μC / cm ² . The obtained pattern had good adhesion to the substrate, and no peeling of the pattern was observed.

(Reference Example 4)
This embodiment will be described with reference to FIG.

  First, naphthoquinonediazide as a diazo compound was added to the polymer obtained in Synthesis Example 1 in an amount of 40 wt%, and this was used as an 8 wt% cyclohexanone solution to prepare a resist solution of the present invention.

  On the other hand, as shown in FIG. 1A, a novolak-based photoresist was applied on a Si wafer 11 and hard-baked at 190 ° C. to form an underlayer 12 having a thickness of 0.8 μm. Further, SOG (spin-on-glass) was applied on the underlayer and baked at 200 ° C. to form a 0.1 μm-thick intermediate layer 13.

  The above cyclohexanone solution was filtered through a 0.2 μm membrane filter, applied to a Si wafer provided with an underlayer and an intermediate layer by spin coating, and prebaked at 100 ° C. for 90 seconds to obtain a solution shown in FIG. 2), an upper resist film 14 having a thickness of 0.2 μm was formed.

The resist film 14 is irradiated with ArF excimer laser light (NA = 0.55) having a wavelength of 193 nm to expose the resist film 14 as shown in FIG. 1 (c). Development was carried out with a 2.38% aqueous solution of TMAH as a liquid. As a result, with a DOSE amount of 130 mJ / cm ² , a 0.15 μm line and space pattern 14 a as shown in FIG. 1D could be resolved. The obtained pattern had good adhesion to the substrate, and no peeling of the pattern was observed.

Subsequently, using the resist pattern 14a formed as described above as an etching mask, the SOG film 13 of the intermediate layer is etched by CF ₄ RIE to form a patterned SOG film as shown in FIG. 13a was formed. Further, using the patterns 14a and 13a obtained as described above as an etching mask, the lower novolak-based photoresist film 12 was etched by O ₂ RIE. As a result, the resist pattern was faithfully transferred, and a patterned novolak-based photoresist film 12a as shown in FIG. 1F was obtained.

(Reference Example 5)
The polymer obtained in Synthesis Example 2 was used as an 8 wt% cyclohexanone solution. This solution was filtered through a 0.2 μm membrane filter, applied to a Si wafer by spin coating, and prebaked at 100 ° C. for 90 seconds to form a 0.3 μm thick resist film.

The resist film is exposed by irradiating it with ArF excimer laser light (NA = 0.55) having a wavelength of 193 nm. Subsequently, the exposed resist film is exposed to a 2.38% aqueous solution of TMAH as an alkaline developer. Exposure. As a result, a 0.15 μm line-and-space pattern could be resolved with a DOSE amount of 100 mJ / cm ² . The adhesion between the resist pattern and the substrate was good, and no peeling of the pattern was observed.

(Reference Example 6)
To the polymer obtained in Synthesis Example 3, naphthoquinonediazide as a diazo compound was added in an amount of 20% by weight of the polymer to obtain an 8% by weight cyclohexanone solution. This solution was filtered with a 0.2 μm membrane filter. The solution thus obtained was applied on a Si wafer by spin coating, and prebaked at 100 ° C. for 90 seconds to form a resist film having a thickness of 0.17 μm.

This resist film was exposed by irradiating an ArF excimer laser (NA = 0.55), and then the exposed resist film was developed with an alkali developing solution. As a result, a 0.17 μm line-and-space pattern could be resolved with a DOSE amount of 140 mJ / cm ² . The obtained pattern had good adhesion to the substrate, and no peeling of the pattern was observed at all.

(Reference Example 7)
To the polymer obtained in Synthesis Example 4, 30% by weight of naphthoquinonediazide as a diazo compound was added, and this was dissolved in a 3: 1 mixed solution of cyclohexanone / PGMEA to obtain an 8% by weight solution. This solution was filtered with a 0.2 μm membrane filter. On the other hand, the surface treatment was previously performed on the Si wafer with HMDS (hexamethyldisilazane). The above-described solution was applied onto the Si wafer by spin coating, and prebaked at 120 ° C. for 90 seconds to form a 0.2 μm-thick resist film.

The resist film was exposed by irradiating ArF excimer laser light (NA = 0.55), and then the exposed resist film was developed with an alkali developing solution. As a result, a 0.15 μm line-and-space pattern could be resolved with a DOSE amount of 135 mJ / cm ² . The adhesion between the resist pattern and the substrate was good, and no peeling of the pattern was observed.

(Reference Example 8)
This embodiment will be described with reference to FIG.

First, as shown in FIG. 2A, a 0.8 μm thick silicon oxide film 22 is formed on a Si wafer 21 by CVD (Chemical Vapor Deposition), and then a thickness of Al—Si—Cu is formed. A lower wiring layer 23 having a thickness of about 0.7 μm, an interlayer insulating film 24 made of a SiO ₂ film by a CVD method, and an upper wiring film 25 made of Al—Si—Cu having a thickness of about 0.7 μm were sequentially formed.

  On the other hand, 30 wt% of naphthoquinonediazide as a diazo compound was added to the polymer obtained in Synthesis Example 4, and this was dissolved in a 3: 1 mixed solution of cyclohexanone / PGMEA to obtain an 8 wt% solution. This solution was filtered with a 0.2 μm membrane filter. The solution thus obtained was applied on a Si wafer by spin coating, and prebaked at 120 ° C. for 90 seconds to form a 0.3 μm-thick resist film 26 on the upper wiring film 25.

Next, the resist film 26 is exposed by irradiating an ArF excimer laser beam (NA = 0.55) with a DOSE amount of 135 mJ / cm ² , and the exposed resist film is developed with an alkali developing solution. A resist pattern 26a as shown in FIG. Further, using the resist pattern 26a as a mask, the upper wiring film was etched by RIE using CCl ₄ gas to form the upper wiring 25a.

After that, the resist pattern 26a was carbonized and removed in O ₂ plasma to obtain a two-layer wiring as shown in FIG. 2C. The upper wiring 25a was hardly affected by steps caused by the lower wiring film and the like, and had a design error of ± 0.05 μm with respect to the design dimension of 0.35 μm. When an upper layer wiring having a wiring interval of 0.35 μm and a line width of 0.35 μm was formed, no defect such as disconnection or short circuit occurred.

(Reference Example 9)
This embodiment will be described with reference to FIG.

  First, an onium salt (triphenylsulfonium triflate) as an acid generator was added to the polymer represented by the aforementioned chemical formula (P-1) to prepare a PGMEA solution. Next, the PGMEA solution was filtered through a 0.2 μm membrane filter to obtain a solution for forming a lower resist. Further, NPNQ as a photosensitive agent was mixed at 40 wt% to the polymer obtained in Synthesis Example 4 to obtain a xylene solution. The xylene solution was filtered through a 0.2 μm membrane filter to obtain a solution for forming an upper resist.

  On the other hand, as shown in FIG. 3A, a 0.8 μm thick silicon oxide film 32 was formed on a Si wafer 31 by a CVD method. A resist solution for forming a lower layer resist prepared as described above was applied thereon by spin coating, and prebaked at 120 ° C. for 90 seconds to form a lower layer resist film 33 having a thickness of 0.4 μm.

  Further, on the lower resist film 33, the resist solution for forming an upper resist prepared as described above is applied by spin coating, and prebaked at 120 ° C. for 90 seconds to form an upper resist film 34 having a thickness of 0.2 μm. Formed.

  The obtained upper resist film 34 was irradiated with an ArF excimer laser and developed with an alkali developing solution. As a result, a resist pattern 34a having a line width of 0.15 μm as shown in FIG. 3B was obtained. Further, using the resist pattern 34a as a mask, the lower resist film 33 is exposed to light using an interference filter that transmits light near a wavelength of 220 nm, and developed to obtain a lower resist pattern 33a as shown in FIG. Was.

Using the resist patterns 34a and 33a thus obtained as a mask, the silicon oxide film 32 is etched by RIE using CCl ₄ gas to obtain a silicon oxide pattern 32a as shown in FIG. _{(2) The} resist pattern was carbonized and removed in plasma to obtain a structure as shown in FIG.

  According to this reference example, it was found that a pattern having a line width of 0.15 μm can be formed also on the silicon oxide film.

(Example)
First, naphthoquinonediazide (naphthoquinonediazide-4-sulfonate of 2,3,4,4'-tetrahydroxybenzophenone) was added as a photosensitizer to the polymer obtained in Synthesis Example 1, and this was mixed with PGMEA-cyclohexanone. Dissolved in the solution. Next, this solution was filtered through a 0.2 μm membrane filter to obtain a solution for forming a lower resist. Further, 3 wt% of naphthalidyl triflate and 20 wt% of NV4THP were added to the polymer obtained in Synthesis Example 5 to obtain an ethyl lactate solution. This solution was filtered through a 0.2 μm membrane filter to obtain a solution for forming an upper layer resist.

  On the other hand, as shown in FIG. 3A, a 0.8 μm thick silicon oxide film 32 was formed on a Si wafer 31 by a CVD method. The resist solution for forming a lower layer resist prepared as described above was applied thereon by spin coating, and prebaked at 120 ° C. for 90 seconds to form a lower layer resist film 33 having a thickness of 0.4 μm.

  Further, on the lower resist film 33, the resist solution for forming an upper resist prepared as described above is applied by spin coating, and prebaked at 120 ° C. for 90 seconds to form an upper resist film 34 having a thickness of 0.2 μm. Formed.

  The obtained upper resist film 34 was exposed to an electron beam of 5 keV and subjected to alkali development, whereby a resist pattern 34a having a line width of 0.13 μm as shown in FIG. 3B was obtained. Further, using this resist pattern as a mask, the lower resist 33 was exposed to light by irradiating ArF excimer laser light and developed to obtain a lower resist pattern 33a as shown in FIG. 3 (c).

Using the resist patterns 34a and 33a thus obtained as a mask, the silicon oxide film 32 is etched by RIE using CCl ₄ gas to obtain a silicon oxide pattern 32a as shown in FIG. _{(2) The} resist pattern was carbonized and removed in plasma to obtain a structure as shown in FIG.

  According to this example, it was found that a pattern having a line width of 0.13 μm can be formed also on the silicon oxide film.

(Reference Example 10)
First, an onium salt (triphenylsulfonium triflate) as an acid generator was added to the polymer represented by the aforementioned chemical formula (P-1) to prepare a PGMEA solution. Next, the PGMEA solution was filtered through a 0.2 μm membrane filter to obtain a solution for forming a lower resist. Further, to the polymer obtained in Synthesis Example 5, AdTB obtained in Synthesis Example 6 was added as a dissolution inhibitor, and 3% of naphthalidyl triflate was further added to obtain a xylene solution. This solution was filtered through a 0.2 μm membrane filter to obtain a solution for forming an upper resist.

  Using the solution for lower resist prepared as described above, a lower resist film having a thickness of 0.4 μm was formed on the Si wafer. A solution for forming an upper resist was applied thereon by spin coating, and prebaked at 120 ° C. for 90 seconds to form an upper resist film having a thickness of 0.3 μm.

The upper resist film thus obtained was exposed to an ArF excimer laser at 30 mJ / cm ² , and baked at 110 ° C. for 1 minute. Next, when developed with a 0.238% TMAH alkaline developer, an upper layer resist pattern having a line width of 0.15 μm could be formed.

  Further, using the obtained upper resist pattern as a mask, the lower resist was exposed to light using an interference filter that transmits light near a wavelength of 250 nm, and baked at 140 ° C. for 1 minute. Finally, when developed with a 2.38% TMAH aqueous solution, a 0.15 μm pattern could be transferred onto the substrate.

(Reference Example 11)
First, an onium salt (triphenylsulfonium triflate) as an acid generator was added to the polymer represented by the aforementioned chemical formula (P-1) to prepare a PGMEA solution. Next, the PGMEA solution was filtered through a 0.2 μm membrane filter to obtain a solution for forming a lower resist. Further, to the polymer obtained in Synthesis Example 5, 20 wt% of NV4THP obtained in Synthesis Example 7 was added as a dissolution inhibitor, and 3 wt% of naphthalidyl triflate was further added to obtain a xylene solution. This solution was filtered through a 0.2 μm membrane filter to obtain a solution for forming an upper resist.

  Using the solution for lower resist prepared as described above, a lower resist film having a thickness of 0.4 μm was formed on the Si wafer. A solution for forming an upper resist was applied thereon by spin coating, and prebaked at 120 ° C. for 90 seconds to form an upper resist film having a thickness of 0.2 μm.

The upper resist film thus obtained was exposed to ArF excimer laser at 35 mJ / cm ² , and baked at 110 ° C. for 1 minute. Subsequently, when the resist was developed with a 0.238% TMAH alkaline developer, an upper resist pattern having a line width of 0.14 μm could be formed.

Further, using the obtained upper resist pattern as a mask, the lower resist was exposed to light at 5 mJ / cm ² using an interference filter that transmits light near a wavelength of 230 nm, and baked at 140 ° C. for 1 minute. Finally, when developed with a 2.38% TMAH aqueous solution, a 0.14 μm pattern could be transferred onto the substrate.

  From the above results, it is understood that the photosensitive material of the present invention using an alkali-soluble acrylic resin as a base polymer has high transparency to short wavelength light such as ArF excimer laser light. On the other hand, it was confirmed that a conventional resist mainly containing poly (hydroxystyrene) or a novolak resin had an absorption of 30 or more per 1 μm at a wavelength of 193 nm, and hardly transmitted ArF excimer laser light.

(Comparative example)
To the polymer obtained in Synthesis Example 1 was added 1% by weight of triphenylsulfonium triflate as an acid generator based on the polymer to obtain a cyclohexanone solution, and a resist film was prepared in the same manner as in Reference Example 1 except that this solution was used. Was formed. The resist film is exposed by irradiating an ArF excimer laser beam (NA = 0.55), and immediately after the exposure, is heated at 150 ° C. for 90 seconds. Development was carried out with a 38% aqueous alkaline solution. As a result, a line and space pattern of 0.25 μm could be partially resolved with a DOSE amount of 30 mJ / cm ² . However, the adhesion between the resist pattern and the substrate was poor, and it was confirmed by an optical microscope that uneven peeling occurred in the resist film.

Sectional drawing showing an example of the process of the resist pattern formation method. FIG. 9 is a cross-sectional view illustrating another example of the step of the resist pattern forming method. FIG. 9 is a cross-sectional view illustrating another example of the step of the resist pattern forming method according to the embodiment of the present invention.

Explanation of reference numerals

11, 21, 31: Si wafer; 12: Underlayer;
12a: novolak-based photoresist film pattern; 13: intermediate layer 13a: SOG film pattern; 14: resist film; 14a: resist pattern 22, 32: silicon oxide film; 23: lower wiring film; 24: interlayer insulating film 25: upper layer 25a: upper layer wiring; 26: resist film 26a: resist pattern; 32a: silicon oxide pattern; 33: lower layer resist film 33a: lower layer resist pattern; 34: upper layer resist film 34a: upper layer resist pattern.

Claims (10)

Forming a lower photosensitive material film on the substrate,
Forming an upper photosensitive material film containing a substituted or unsubstituted benzene ring or a polycyclic fused aromatic ring or an alicyclic skeleton on the lower photosensitive material film,
A step of irradiating a predetermined region of the upper photosensitive material film with an electron beam to perform exposure,
A step of dissolving and removing an exposed portion or an unexposed portion of the upper photosensitive material film after the exposure with an alkaline aqueous solution, and
Using the upper photosensitive material film pattern obtained after the developing step as a mask, light having a wavelength of 190 to 260 nm is collectively irradiated, and a developing process is performed to selectively dissolve and remove the exposed portions. Transferring a conductive material film pattern to the lower photosensitive material film.   2. The method according to claim 1, wherein the lower photosensitive material film contains a phenolic resin. The method according to claim 1, wherein the phenolic resin contains a compound represented by the following chemical formulas (P-1) to (P-4).

  2. The method according to claim 1, wherein the lower photosensitive material film includes an acrylic resin having an alicyclic skeleton.   The method according to claim 4, wherein the alicyclic skeleton is a menthyl group or an adamantyl group.   6. The method according to claim 1, wherein the upper photosensitive material film contains a benzene ring or a polycyclic fused aromatic ring.   7. The method according to claim 6, wherein the upper photosensitive material film contains a polycyclic fused aromatic ring selected from naphthalene and anthracene.   7. The method according to claim 6, wherein the upper photosensitive material contains a material containing a benzene ring selected from a phenol resin and a novolak resin.   7. The method according to claim 1, wherein the upper photosensitive material film includes an alicyclic skeleton.   The method according to claim 9, wherein the alicyclic skeleton includes a menthyl group or an adamantyl group.

Images