JP3806121B2 - Resist pattern forming method - Google Patents

Description

The present invention relates to a semiconductor device, TFT (thin film transistor), a method of forming a resist pattern of the microfabrication in the production process, such as an optical disk.

  In the manufacturing process of electronic parts such as LSIs, a microfabrication technique using photolithography has been adopted. That is, first, a resist solution is applied onto a substrate or the like to form a resist film, and then the resulting resist film is exposed to pattern light, and then subjected to treatment such as alkali development to form a resist pattern. Form. Subsequently, the surface of the substrate or the like exposed using this resist pattern as an etching resistant mask is dry-etched 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 this point of view, resists containing aromatic compounds have been widely used so far. Specifically, many resists based on alkali-soluble novolak resins and the like have been developed.

  On the other hand, with the high-density integration of LSIs and the like, the fine processing technology as described above has recently reached the sub-half micron order, and such miniaturization is expected to become more prominent in the future. For this reason, the shortening of the wavelength of the light source in photolithography is progressing and attempts are being made to form a fine resist pattern using ArF excimer laser light having a wavelength of 193 nm or YAG laser having a wavelength of 218 nm and a fifth harmonic light.

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

By the way, a pattern forming method called PCM (Portable Conformable Mask) method was introduced in 1979, Proc. SPIE. 174, 114; J. et al. Indicated 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 upper layer resist pattern as a mask. As what was performed by this PCM method, A. W. McCullough et al., 1986, Proc. SPIE. 631, 316 report as follows. In this example, PMGI (polydimethylglutarimide) is used as a lower layer material, and a pattern is formed by batch exposure using a pattern formed of an upper layer of novolak-naphthoquinonediazide as a mask.

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

  As described above, a resist based on a novolak resin has a high dry etching resistance and can be alkali-developed, but has insufficient transparency with respect to short-wavelength light. Therefore, an ArF excimer laser beam or a YAG laser 5 Development of a resist suitable for photolithography using double harmonic light is strongly desired. In consideration of such points, recently, a resist containing an alicyclic compound instead of an aromatic compound has been attracting attention. For example, JP-A-4-39665 discloses resistance to dry etching and transparency to short-wavelength light. In both cases, a resist having a base resin made of a polymer having an adamantane skeleton has been proposed. Further, here 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, when a resist pattern is formed by alkali development in this way for a resist containing an alicyclic compound, alkali solubility is greatly different between an alicyclic structure such as an adamantane skeleton and a carboxylic acid group. A problem occurs. For example, the dissolution / removal of a predetermined region of the resist film becomes uneven during development, resulting in a decrease in resolution, while partial dissolution occurs in the region where the resist film should remain, causing cracks and surface roughness. Cause. Further, the alkaline solution may permeate 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. Furthermore, in the polymer, the phase separation between the alicyclic structure portion and the carboxylic acid portion is likely to proceed, and it is difficult to prepare a uniform resist solution and the coatability is not sufficient.

  A chemically amplified resist using acid catalysis has been developed as a highly sensitive resist. However, this chemically amplified resist is easily affected by the time until PEB after exposure. In particular, the shape of the resist pattern obtained due to the influence of amines contained in the atmosphere is deteriorated, and in some cases, peeling from the substrate may occur.

  Further, as described above, in the conventional PCM method, the material used for lithography with a longer wavelength than the lower layer photosensitive material is used for the upper layer photosensitive material, and what is the advantage of forming an optically fine pattern? It did not exist.

  Therefore, the present invention can be performed with an electron beam and has a high absorption wavelength band that can be used as a mask during exposure of the lower layer, and a PCM using a specific material that is difficult to form a mixing or the like as the upper layer material. It is an object of the present invention to provide a practical method for forming a resist pattern.

A resist pattern forming method according to an aspect of the present invention includes a step of forming a lower photosensitive material film on a substrate, and a substituted or unsubstituted benzene ring or polycyclic fused aromatic ring on the lower photosensitive material film. A step of forming an upper photosensitive material film containing, a step of irradiating a predetermined region of the upper photosensitive material film with an electron beam and exposing, and an exposed portion or an unexposed portion of the upper photosensitive material film after the exposure. The exposed portion is dissolved and removed with an aqueous alkali solution and developed, and the upper photosensitive material film pattern obtained after the developing step is used as a mask to collectively irradiate ArF excimer laser light to develop the exposed portion. And a step of transferring the upper photosensitive material film pattern onto the lower photosensitive material film by selectively dissolving and removing.

  According to the present invention, a specific material that can be performed with an electron beam and has a high absorption wavelength band that can be used as a mask during exposure of the lower layer and is difficult to form 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, an alkali-soluble resin made of a copolymer such as acrylic acid and methacrylic acid can be used as the alkali-soluble resin as the photosensitive material . More specifically, a copolymer composed of menthyl methacrylate, methyl methacrylate and methacrylic acid ; a copolymer composed of menthyl acrylate, methyl methacrylate and methacrylic acid.

In the present invention, since the alkali-soluble resin as the photosensitive material has a condensed polycyclic structure , in addition to the advantage of good transparency at 193 nm, the resist pattern to be obtained has high dry etching resistance. Can do. In the case of having an alicyclic structure , examples thereof include a cyclic cyclo compound and a cyclic bicyclo compound represented by the general formula C _n H _2n (n is an integer of 3 or more), and condensed rings thereof. Specifically, cyclobutane ring, cyclopentane ring, cyclohexane ring, cycloheptane ring and those having bridged hydrocarbons introduced therein, spiroheptane, spirooctane and other spiro rings, norbornyl ring, adamantyl ring, bornene ring, Terpene rings such as menthyl ring and menthane ring, tsujang, sabinene, tujon, caran, karen, pinan, norpinan, bornane, fencan, tricyclene, steroid skeletons such as cholesteric ring, bile acid, digitaloids, camphor ring, iso camphor ring, Examples include sesquiterpene rings, sandton rings, diterpene rings, triterpene rings, and steroid saponins .

As what has condensed polycyclic structure, what is shown below is mentioned, for example. For example, indene, indane, benzoburden, 1-indanone, 2-indanone, 1,3-indadione, ninhydrin, naphthalene, methylnaphthalene, ethylnaphthalene, dimethylnaphthalene, cadalene, vinylnaphthalene, 1,2-dihydronaphthalene, 1,4 -Dihydronaphthalene, 1,2,3,4-tetrahydronaphthalene tetralin, 1,2,3,4,5,6,7,8-octahydronaphthalene, cis-decalin, trans-decalin, fluoronaphthalene, chloronaphthalene, Bromonaphthalene, iodonaphthalene, dichloronaphthalene, (chloromethyl) naphthalene, 1-naphthol, 2-naphthol, naphthalenediol, 1,2,3,4-tetrahydro-1-naphthol, 1,2,3,4-tetrahydro- 2-naphtho 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, naphthalene dicarbaldehyde, hydroxy naphthaldehyde, dinaphthyl ketone, 1 (2H) -naphthalene, α-tetralone, β-tetralone, α-decalone, β- Decalon, 1,2-naphthoquinone, 1,4-naphthoquinone, 2,6-naphthoquinone, 2-methyl-1,4-naphthoquinone, 5-hydroxy-1,4-naphthoquinone, isonaftazaline, naphthoic acid, 1-naphthol-4 -Carboxylic acid, Naphthalic acid, Na 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, anthrorobin, chrysarobin, oxanthrone, anthracenecarboxylic acid, Anthramine, nitroanthracene, anthracenequinone, anthraquinone, methylanthraquinone, hydroxyanthraquinone, phenanthrene, Enanthrol, phenanthrene hydroquinone, phenanthraquinone, biphenylene, s-indacene, as-indacene, phenalene, tetracene, chrysene, 5,6-chrysoquinone, pyrene, 1,6-pyrenequinone, triphenylene, benzo [α] anthracene, benzo [Α] anthracene-7,12-quinone, benzanthrone, acanthrylene, acephenanthrylene, acephenanthrene, 17H-cyclopenta [α] -phenanthrene, fluoranthene, preaden, pentacene, pentaphen, picene, pyrylene, dibenzo [a , J] anthracene, benzo [α] pyrene, coronene, pyranthrene, and pyranthrone .

  When the alkali-soluble resin in the present invention includes an alicyclic skeleton, the polymer includes, for example, a polymerizable compound having an alicyclic structure into which an acidic substituent is introduced and a polymerizable double bond in the molecule. It can be easily obtained by polymerization by radical polymerization, cationic polymerization, anionic polymerization or the like, or by polymerization in the presence of a Ziegler-Natta catalyst. In general, a polymerizable compound having an alicyclic structure and a polymerizable double bond in the molecule can be made 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 be formed into a film. May be.

At this time, from the viewpoint of improving adhesion between the alkali solubility adjustment and resist film and the substrate polymer, acrylic acid or maleic anhydride and esters substituents, vinyl phenol, vinyl naphthol, hydroxyethyl methacrylate, SO _2, etc. It is preferable to copolymerize with. Further, the alkali-soluble group of these alkali-soluble compounds may be copolymerized with a compound formed by protecting with an acid-decomposable group having a dissolution inhibiting ability in an alkaline solution. However, considering the transparency of the resist to short-wavelength light, it is preferable to copolymerize with a compound that does not have a molecular skeleton that has a large light absorption in the short-wavelength region, such as a benzene nucleus. The absorbance of the polymer with respect to is preferably 4 or less per 1 μm, and more preferably 2 or less .

  However, the copolymerization ratio of an 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 it is less than 1%, the alkali solubility of the polymer may be insufficient. Conversely, if it exceeds 50%, non-uniform dissolution occurs and it is difficult to form a resist pattern.

  The average molecular weight of the polymer as described above 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 will be disadvantageous to form a resist film with sufficient mechanical strength. Conversely, if it exceeds 500,000, a resist pattern with good resolution will be formed. It is difficult to do. These compounds are usually a mixture containing components having various molecular weights. However, in the present invention, even compounds having relatively low molecular weights are effective. For example, non-uniform dissolution can be suppressed even when many molecular weights of 500 to 1,000 are localized. Further, in this case, even if a large amount of monomers remain in the resin, there is little deterioration in the solubility characteristics with respect to the alkaline developer and the dry etching resistance of the resulting resist pattern.

The photosensitive material used in the pattern forming method of the present invention can be prepared by dissolving a predetermined compound in a predetermined solvent.

Examples of the solvent used here include ketone solvents such as cyclohexanone, acetone, methyl ethyl ketone, and methyl isobutyl ketone; cellosolv solvents such as methyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, and butyl cellosolve acetate; ethyl acetate, butyl acetate, Examples thereof include ester solvents such as isoamyl acetate and γ-butyrolactone; glycol solvents such as propylene glycol monomethyl ether acetate; nitrogen-containing solvents such as dimethyl sulfoxide, hexamethylphosphoric triamide dimethylformamide and N-methylpyrrolidone. Furthermore, a mixed solvent in which dimethyl sulfoxide, dimethylformaldehyde, N-methylpyrrolidinone or the like is added thereto can be used to improve solubility. Furthermore, propionic acid derivatives such as methyl propionate, etc. lactates and PGMEA such ethyl lactate (propylene glycol monomethyl ether acetate) may also be used are preferably of low toxicity. In the present invention, such solvents can be used alone or in admixture of two or more. Further, isopropyl alcohol, ethyl alcohol, methyl alcohol, butyl alcohol, n-butyl alcohol, s-butyl alcohol, t- Aliphatic alcohols such as butyl alcohol and isobutyl alcohol, and aromatic solvents such as toluene and xylene may be contained.

The pattern formation process of the present invention will be described. First, a photosensitive material solution dissolved in an organic solvent as described above is applied on a predetermined substrate by a spin coating method or a dipping method, and then dried at 150 ° C. or lower, preferably 70 to 120 ° C. A film is formed.

As the substrate here, for example, a silicon wafer, a silicon wafer on which various insulating films, electrodes, wirings and the like are formed, a blank mask, a III-V group compound semiconductor wafer such as GaAs and AlGaAs, chromium or chromium oxide A vapor deposition mask, an aluminum vapor deposition substrate, a BPSG coated substrate , a PSG coated substrate, an SOG coated substrate, a carbon film sputtering 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 film thickness of about 0.5 to 5 μm, a photosensitive material can be applied and used as an upper resist.

  In addition, although the film thickness of the resist film formed on a board | substrate after evaporation of a solvent changes with uses, it is preferable to exist in the range of 0.05-15 micrometers normally. If it is out of this range, the sensitivity may be remarkably lowered or the resolution may be lowered.

Next, the resist film formed on the substrate is irradiated with 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 . Note that 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 resist film in the exposed or unexposed area is selectively dissolved and removed in an alkaline solution to form a desired pattern. In this case, specific examples of the alkaline solution include organic alkaline aqueous solutions such as tetramethylammonium hydroxide aqueous solution and choline aqueous solution, inorganic alkaline aqueous solutions such as potassium hydroxide and sodium hydroxide, and alcohols and surfactants added thereto. A solution. Here, the concentration of the alkaline solution is preferably 15 wt% or less from the viewpoint of sufficient difference in dissolution rate between the exposed portion and the unexposed portion.

The substrate and resist pattern after development may be rinsed using water or the like.

Therefore , the resist pattern formed by the method of the present invention has extremely good resolution, and also the adhesion between the resulting resist pattern and the substrate is high, so that peeling from the substrate does not occur at all. Therefore, for example, by dry etching using a resist pattern formed by the method of the present invention as an etching mask, an ultrafine pattern of quarter micron or less such as an exposed substrate can be faithfully transferred.

In addition, when an alkali-soluble resin containing a condensed polycyclic skeleton is blended as a component of the upper photosensitive material film , even if one carbon-carbon bond is broken, the other bond remains in the obtained resist pattern. Therefore, such a resist pattern has high dry etching resistance.

In the pattern formation process of the present invention , there is no problem even if other steps other than the steps described above are added. For example, a planarization layer forming step as a base of the resist film, an improvement in adhesion between the resist film and the base It is possible to appropriately carry out a pretreatment step for the purpose, a rinsing step for removing the resist film with water after development of the resist film, and a re-irradiation step of ultraviolet rays before dry etching.

In the pattern forming method of the present invention, the upper layer is exposed by a low-acceleration electron beam, and the lower layer exposed by an ArF excimer laser beam is formed.

As the photosensitive material used for the upper layer, those having a substituted or unsubstituted polycyclic fused aromatic ring or benzene ring having absorption in a wavelength range of 190 to 260 nm that can be exposed and developed with a low acceleration electron beam with high sensitivity. The photosensitive material used for the lower layer is preferably a material that 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 absorption near 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 near 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 substituted or unsubstituted naphthalene and anthracene in the condensed polycyclic skeleton. Moreover, as what has a benzene ring, a phenol resin, a novolak resin, etc. are mentioned.

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

  By the way, when forming the photosensitive material layer of an upper layer and a lower layer, mixing which a solvent mixes between layers often becomes a problem. One solution is to form a layer called a barrier coat between the photosensitive material of the upper layer and the lower layer, which does not cause mixing with either the upper layer or the lower layer, when forming the layer. However, from the viewpoint of shortening the process and reducing the material, it is preferable not to include such a barrier coat layer.

In the pattern forming method of the present invention, since the material which does not easily generate mixing is used, the influence is extremely small. Furthermore, in order to prevent mixing, a material that is difficult to dissolve is used for the lower layer .

As the 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 composed 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>
Menthyl methacrylate, methyl methacrylate, and methacrylic acid were mixed in an amount of 33 mol%, 29 mol%, and 38 mol%, respectively, and a total of 6.0 g was mixed with 20 g of tetrahydrofuran (THF). Subsequently, 0.73 g of azoisobutyl nitrile (AIBN) was added to the obtained solution and reacted by heating at 60 ° C. for 35 hours with stirring, and then the reaction solution was added dropwise to 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>
An equimolar amount of hydroxyethyl methacrylate and 1,2-naphthoquinonediazide-4-sulfonic acid chloride were dissolved in dioxane to obtain a 10 wt% dioxane solution. Subsequently, while keeping this solution at 20 ° C., an amount of triethylamine corresponding to 1.2 equivalents of 1,2-naphthoquinonediazide-4-sulfonic acid chloride was slowly dropped into the dioxane solution to precipitate the precipitated salt. The solution was filtered and poured into a large amount of 0.2% oxalic acid solution. The precipitate was filtered and then washed with ion-exchanged water, followed by vacuum drying to obtain hydroxyethyl methacrylate naphthoquinone diazide sulfonate.

  Next, menthyl methacrylate, hydroxyethyl methacrylate naphthoquinone diazide sulfonic acid ester, and methacrylic acid were mixed with 20 g of tetrahydrofuran (THF) in a total amount of 33 mol%, 29 mol%, and 38 mol%, respectively. Subsequently, 0.73 g of azoisobutyl nitrile (AIBN) was added to the obtained solution and reacted by heating at 60 ° C. for 35 hours with stirring, and then the reaction solution was added dropwise to 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 a condensed polycyclic structure in the side chain>
A total of 6.0 g of vinyl naphthalene, methyl methacrylate, and methacrylic acid, 30 mol%, 30 mol%, and 40 mol%, 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 while 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 an amount of 15 mol%, 20 mol%, 30 mol%, and 35 mol%, respectively, and 6.0 g in total with 20 g of tetrahydrofuran (THF). Subsequently, 0.60 g of azoisobutyronitrile (AIBN) was added to the obtained solution and reacted by heating at 60 ° C. for 35 hours while 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 an alicyclic structure and a condensed polycyclic structure in the side chain>
Vinyl naphthalene, menthyl acrylate, tetrahydropyranyl methacrylate, and methacrylic acid were mixed in 26.2 mol%, 19.4 mol%, 21.6 mol%, 32.7 mol%, respectively, 9.43 g in total was mixed with 20 g of tetrahydrofuran (THF). Subsequently, 1.6 g of azoisobutyronitrile (AIBN) was added to the obtained solution, and the mixture was reacted by heating at 60 ° C. for 40 hours while 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 6,000.

(Synthesis Example 6)
<Dissolution inhibitor: Synthesis of 1-adamantylcarbonyl-2,2'-ditert-butoxycarbonylethane>
0.02 mol of ditert-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 completion of hydrogen generation, the reaction system was brought to room temperature, and 0.02 mol of adamantyl (bromomethyl) ketone in THF was introduced. Then, it was made to react 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 then twice with water. Finally, it was dried and concentrated to give 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 this 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 sodium hydroxide lump was added to this solution, and after stirring for a while, the residue was filtered off, the oil layer was concentrated to dryness under reduced pressure, further dissolved in ethyl acetate, and washed twice with a 5% oxalic acid aqueous solution. Then, this was separated, dried over anhydrous sodium sulfate, and concentrated to dryness to obtain pyranylated naphthol novolak (NV4THP).

(Synthesis Example 8)
<Synthesis of photosensitizer>
After 0.1 g of α-naphthol was dissolved in THF, 0.1 mol of 1,2-naphthoquinonediazide-4-sulfonyl chloride was added to the THF solution. While stirring this mixed solution at 0 ° C., 0.1 mol of triethylamine was gradually added dropwise thereto. The precipitated salt was filtered off, the reaction solution was concentrated to dryness, and recrystallized using ethanol-hexane to obtain a naphthoquinonediazide compound (NPNQ) of naphthol.

(Reference Example 1)
To the polymer obtained in Synthesis Example 1, 40 wt% of naphthoquinonediazide as a diazo compound was added, and this was used as an 8 wt% cyclohexanone solution. This solution was filtered through a 0.2 μm membrane filter, and then applied onto 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 ArF excimer laser light (NA = 0.55) with a wavelength of 193 nm. Subsequently, the exposed resist film is treated with tetramethylammonium hydroxide (TMAH) as an alkali developer. ) And 2.38% aqueous alkali solution. As a result, a 0.15 μm line and space pattern could be resolved with a DOSE amount of 130 mJ / cm ² . In addition, the adhesiveness with the board | substrate of the obtained pattern was also favorable, and peeling of a pattern was not observed at all.

(Reference Example 2)
To the polymer obtained in Synthesis Example 1, 45 wt% of a Melazolic acid diazo compound was added to obtain an 8 wt% ethyl lactate solution. This solution was filtered through a 0.2 μm membrane filter, applied onto a Si wafer by spin coating, and then pre-baked at 120 ° C. for 90 seconds to form a resist film having a thickness of 0.2 μm.

This resist film is exposed by irradiating ArF excimer laser light (NA = 0.55) with a wavelength of 193 nm, and then the resist film after exposure is treated with 2.38% alkali of TMAH as an alkaline developer. Developed with 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 . In addition, the adhesiveness with the board | substrate of the obtained pattern was also favorable, and peeling of a pattern was not observed at all.

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

This resist film was exposed with 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 line and space pattern of 0.15 μm could be resolved with an acceleration voltage of 50 keV and a DOSE amount of 30 μC / cm ² . In addition, the adhesiveness with the board | substrate of the obtained pattern was also favorable, and peeling of a pattern was not observed at all.

(Reference Example 4)
The reference example will be described with reference to FIG.

  First, 40 wt% of naphthoquinonediazide as a diazo compound was added to the polymer obtained in Synthesis Example 1, 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 photoresist was applied on the 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 an intermediate layer 13 having a thickness of 0.1 μm.

  The above-described cyclohexanone solution is filtered through a 0.2 μm membrane filter, and an underlayer and an intermediate layer are provided on a Si wafer by spin coating, followed by pre-baking at 100 ° C. for 90 seconds, and FIG. The upper resist film 14 having a thickness of 0.2 μm as shown in FIG.

The resist film 14 is irradiated with ArF excimer laser light (NA = 0.55) having a wavelength of 193 nm and exposed as shown in FIG. 1C. Subsequently, the exposed resist film is alkali-developed. It developed with the 2.38% alkaline aqueous solution of TMAH as a liquid. As a result, a 0.15 μm line and space pattern 14a as shown in FIG. 1D could be resolved with a DOSE amount of 130 mJ / cm ² . In addition, the adhesiveness with the board | substrate of the obtained pattern was also favorable, and peeling of a pattern was not observed at all.

Subsequently, using the resist pattern 14a formed as described above as an etching mask, the intermediate SOG film 13 is etched by CF ₄ RIE, and 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 photoresist film 12 was etched by O ₂ RIE. As a result, the resist pattern could be faithfully transferred, and a patterned novolac photoresist film 12a as shown in FIG. 1 (f) 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, and then applied onto a Si wafer by spin coating, and pre-baked at 100 ° C. for 90 seconds to form a 0.3 μm thick resist film.

The resist film is exposed by irradiating ArF excimer laser light (NA = 0.55) with a wavelength of 193 nm, and then the exposed resist film is used as a 2.38% alkaline aqueous solution of TMAH as an alkaline developer. And exposed. As a result, a 0.15 μm line and space pattern could be resolved with a DOSE amount of 100 mJ / cm ² . In addition, the adhesiveness 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 wt% of the polymer to obtain an 8 wt% cyclohexanone solution. This solution was filtered through a 0.2 μm membrane filter. The solution thus obtained was applied onto 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.

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

(Reference Example 7)
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 through a 0.2 μm membrane filter. On the other hand, the Si wafer was previously surface-treated with HMDS (hexamethyldisilazane). The above-mentioned solution was applied onto this Si wafer by spin coating, and pre-baked at 120 ° C. for 90 seconds to form a resist film having a thickness of 0.2 μm.

The resist film was exposed by irradiation with ArF excimer laser light (NA = 0.55). Subsequently, the exposed resist film was developed with an alkaline developer. As a result, a line and space pattern of 0.15 μm could be resolved with a DOSE amount of 135 mJ / cm ² . In addition, the adhesiveness between the resist pattern and the substrate was good, and no peeling of the pattern was observed.

(Reference Example 8)
The reference example will be described with reference to FIG.

First, as shown in FIG. 2A, a silicon oxide film 22 having a thickness of 0.8 μm is formed on the Si wafer 21 by CVD (Chemical Vapor Deposition), and then the thickness is made of Al—Si—Cu. A lower wiring layer 23 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 of about 0.7 μm thick made of Al—Si—Cu 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 through a 0.2 μm membrane filter. The solution thus obtained was applied onto a Si wafer by spin coating, and pre-baked at 120 ° C. for 90 seconds to form a resist film 26 having a film thickness of 0.3 μm on the upper wiring film 25.

Next, the resist film 26 is exposed by irradiating ArF excimer laser light (NA = 0.55) with a DOSE amount of 135 mJ / cm ² , and the resist film after the exposure is developed with an alkali developer. A resist pattern 26a as shown in (b) was formed. 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.

Thereafter, the resist pattern 26a was carbonized and removed in O ₂ plasma, whereby a two-layer wiring as shown in FIG. 2C was obtained. The upper layer wiring 25a was hardly affected by the step generated by the lower layer wiring film or the like, and had a design error of ± 0.05 μm with respect to the design dimension of 0.35 μm. In addition, when the upper layer wiring with a wiring interval of 0.35 μm and a line width of 0.35 μm was formed, no defects such as disconnection or short circuit occurred.

(Reference Example 9)
The reference example 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 chemical formula (P-1) described above to prepare a PGMEA solution. Subsequently, this PGMEA solution was filtered through a 0.2 μm membrane filter to obtain a solution for forming a lower layer resist. Further, 40 wt% of NPNQ as a photosensitizer was mixed with the polymer obtained in Synthesis Example 4 to obtain a xylene solution. This 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 silicon oxide film 32 having a thickness of 0.8 μm was formed on the Si wafer 31 by the CVD method. On top of this, the resist solution for forming a lower layer resist prepared as described above was applied 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, a resist solution for forming an upper layer resist prepared as described above is applied onto the lower layer resist film 33 by spin coating, and prebaked at 120 ° C. for 90 seconds to form an upper layer resist film 34 having a thickness of 0.2 μm. Formed.

  When the obtained upper resist film 34 was irradiated with an ArF excimer laser and developed with an alkaline developer, 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 and developed using an interference filter that transmits light having a wavelength of around 220 nm, and developed to obtain a lower resist pattern 33a as shown in FIG. It 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. _The structure as shown in FIG. 3E was obtained by carbonizing and removing the resist pattern in _two plasmas.

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

(Example)
First, naphthoquinonediazide (naphthoquinonediazide-4-sulfonic acid ester of 2,3,4,4′-tetrahydroxybenzophenone) is added as a photosensitizer to the polymer obtained in Synthesis Example 1, and this is 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 layer 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 silicon oxide film 32 having a thickness of 0.8 μm was formed on the Si wafer 31 by the CVD method. On top of this, the resist solution for forming a lower layer resist prepared as described above was applied 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, a resist solution for forming an upper layer resist prepared as described above is applied onto the lower layer resist film 33 by spin coating, and prebaked at 120 ° C. for 90 seconds to form an upper layer resist film 34 having a thickness of 0.2 μm. Formed.

  When the obtained upper resist film 34 was exposed with an electron beam of 5 keV and developed with an alkali, a resist pattern 34a having a line width of 0.13 μm as shown in FIG. 3B was obtained. Furthermore, ArF excimer laser light was irradiated using this resist pattern as a mask to expose the lower resist layer 33 and developed to obtain a lower resist pattern 33a as shown in FIG.

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. _The structure as shown in FIG. 3E was obtained by carbonizing and removing the resist pattern in _two plasmas.

  According to this example, it was found that a pattern with a line width of 0.13 μm can also be formed 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 chemical formula (P-1) described above to prepare a PGMEA solution. Subsequently, this PGMEA solution was filtered through a 0.2 μm membrane filter to obtain a solution for forming a lower layer resist. Further, AdTB obtained in Synthesis Example 6 was added as a dissolution inhibitor to the polymer obtained in Synthesis Example 5, and 3% naphthalidyl triflate was further added to obtain a xylene solution. This solution was filtered through a 0.2 μm membrane filter to obtain an upper resist forming solution.

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

The upper resist film thus obtained was exposed by irradiation with ArF excimer laser at 30 mJ / cm ² and baked at 110 ° C. for 1 minute. Subsequently, when developed with 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 layer resist pattern as a mask, the lower layer resist was exposed using an interference filter that transmits light having a wavelength of around 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 chemical formula (P-1) described above to prepare a PGMEA solution. Subsequently, this PGMEA solution was filtered through a 0.2 μm membrane filter to obtain a solution for forming a lower layer resist. Further, 20 wt% of NV4THP obtained in Synthesis Example 7 as a dissolution inhibitor was added to the polymer obtained in Synthesis Example 5 and 3 wt% of naphthalidyl triflate was added to obtain a xylene solution. This solution was filtered through a 0.2 μm membrane filter to obtain an upper resist forming solution.

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

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

Further, using the obtained upper layer resist pattern as a mask, the lower layer resist was exposed at 5 mJ / cm ² using an interference filter that transmits light having a wavelength of about 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 can be seen that the photosensitive material of the present invention having 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 has been confirmed that a conventional resist mainly composed of poly (hydroxystyrene) or novolak resin has an absorption per 1 μm at a wavelength of 193 nm of 30 or more and hardly transmits ArF excimer laser light.

(Comparative example)
A resist film is obtained in the same manner as in Reference Example 1 except that a cyclohexanone solution is obtained by adding 1 wt% of triphenylsulfonium triflate as an acid generator to the polymer obtained in Synthesis Example 1 and using this solution. Formed. The resist film is exposed by irradiating ArF excimer laser light (NA = 0.55), and immediately after the exposure, it is heated at 150 ° C. for 90 seconds, and further, 2. TMAH as an alkali developer is added. Developed with 38% alkaline aqueous solution. As a result, it was possible to partially resolve a 0.25 μm line and space pattern 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 non-uniform peeling occurred in the resist film.

Sectional drawing showing an example of the process of a resist pattern formation method. Sectional drawing showing the other example of the process of a resist pattern formation method. Sectional drawing showing the other example of the process of the resist pattern formation method concerning embodiment of this invention.

Explanation of symbols

11, 21, 31 ... Si wafer; 12 ... Underlayer;
DESCRIPTION OF SYMBOLS 12a ... Novolak type | system | group photoresist film pattern; 13 ... Intermediate layer 13a ... SOG film pattern; 14 ... Resist film; 14a ... Resist pattern 22, 32 ... Silicon oxide film; 23 ... Lower layer wiring film; 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 (5)

Forming a lower photosensitive material film on the substrate;
Forming an upper photosensitive material film containing a substituted or unsubstituted benzene ring or polycyclic fused aromatic ring on the lower photosensitive material film;
Irradiating a predetermined region of the upper photosensitive material film with an electron beam for exposure;
A step of dissolving and developing 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 layer photosensitive material film pattern obtained after the developing step as a mask, the upper layer photosensitive material is irradiated with ArF excimer laser light and subjected to development to selectively dissolve and remove the exposed portion. And a step of transferring a film pattern to the lower photosensitive material film. The resist pattern forming method according to claim 1, wherein the lower photosensitive material film includes an acrylic resin having an alicyclic skeleton . The resist pattern forming method according to claim 2 , wherein the alicyclic skeleton is a menthyl group or an adamantyl group . The upper layer photosensitive material film, a resist pattern forming method according to any one of claims 1 to 3, characterized in that it contains a material containing polycyclic fused aromatic ring selected from naphthalene and anthracene. The upper layer photosensitive material film, a resist pattern forming method according to any one of claims 1 to 3, characterized in that it contains a material having a benzene ring selected from phenolic resins and novolak resins.

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