JP2006003484A - Pattern forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pattern forming method including resist material removing, that can avoide damages to low dielectric materials or wafer substrates and also contaminations and aggravations of work environments. <P>SOLUTION: On a substrate 10, a low dielectric material film 11 such as an SiO<SB>2</SB>film is formed and a water or alkali soluble polymer layer 12 is formed thereon. And a nonaqueous or non-alkaline soluble polymer layer 13 is formed on this water or alkali soluble polymer layer 12. Then, after coating a resist film 14 and forming, exposing, and developing it, it is etched as deep as reaching the layer (low dielectric material film 11) under the water or alkali soluble polymer layer 12, and the pattern is transferred. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pattern forming method for forming a pattern while removing a resist material, for example, in removing a resist material remaining on an article such as a semiconductor wafer in manufacturing a semiconductor device or the like.

  For example, in the manufacture of semiconductor devices, a resist material is formed on a wafer substrate, a pattern consisting of a resist pattern is formed by a normal photo process, and etching is performed using this as a mask, and then the unnecessary resist material is removed. Then, a circuit is formed. Then, in order to form the next circuit, it is generally performed that a resist material is applied again and a cycle of pattern formation, etching, and removal of the resist material is repeated. Also, when forming circuits on various substrates, the resist material that is no longer needed is removed after the formation of the resist pattern.

  The removal of the resist material that is no longer necessary as described above is generally performed by oxygen ashing (ashing means), a solvent, chemicals, or the like. However, if oxygen ashing is used to remove the resist material, the low dielectric constant (low-k) material may be damaged, or impurities in the resist material may be injected into the low dielectric constant material and the wafer substrate to be contaminated. is there. In addition, the use of solvents and chemicals has the problem of low dielectric constant materials, wafer contamination, and the work environment.

Therefore, in order to solve these problems, conventionally, a resist material removal method using a sheet-like adhesive tape has been proposed (see, for example, Patent Document 1). In this method, an adhesive sheet is attached to an article on which the resist material remains, and the adhesive sheet and the resist material are peeled together to remove the resist material from the article.
JP 2001-143990 A

  However, it is difficult to reliably remove the resist material even by the resist material removing method using the above-described pressure-sensitive adhesive sheets. Therefore, the present invention has a low dielectric constant that is different from any of the above-described removal methods. It is an object of the present invention to provide a pattern forming method with removal of a resist material that can prevent damage to materials and wafer substrates, contamination, and deterioration of the working environment.

  As a result of intensive studies to solve the above problems, the present inventors have formed a water-insoluble or non-alkali-soluble polymer layer in the lower layer of the resist film, and further formed a water-soluble or alkali-soluble polymer layer in the lower layer, After patterning and etching, the water-soluble or alkali-soluble polymer layer exposed on the side wall is dissolved with water or an alkali solution, thereby establishing a method for removing all the upper layers including the water-soluble or alkali-soluble polymer layer. It came to complete.

According to the present invention, (i) forming a water-soluble or alkali-soluble polymer layer on a substrate;
(Ii) forming a water-insoluble or alkali-soluble polymer layer on the water-soluble or alkali-soluble polymer layer;
(Iii) forming a resist film on the water-insoluble or non-alkali-soluble polymer layer;
(Iv) a step of exposing and developing after the step (iii);
(V) etching a layer below the water-soluble or alkali-soluble polymer layer;
(Vi) removing all the upper layer including the water-soluble or alkali-soluble polymer layer with water or an alkali solution;
A pattern forming method is provided.

  In the present invention, a low dielectric material film is preferably formed on the substrate, and a water-soluble or alkali-soluble polymer layer is preferably formed thereon, and the water-soluble or alkali-soluble polymer layer and the water-insoluble polymer layer are preferably formed. Alternatively, an antireflection film layer is preferably formed between the non-alkali soluble polymer layer. Furthermore, it is also preferable that the water-insoluble or non-alkali-soluble polymer layer also serves as an antireflection film layer.

  Examples of the water-soluble or alkali-soluble polymer used in the present invention include any one of N, N-dimethylacrylamide, N-methylacrylamide, and N, N-diethylacrylamide, and methacryloyloxyethyltrimethylammonium chloride. , Acryloyloxyethyltrimethylammonium chloride, and a polymer of any one of acryloyloxyethyltriethylammonium chloride.

  The method of the present invention has the remarkable effect that it avoids damage to and contamination of low dielectric materials and wafers, does not deteriorate the working environment, and can simultaneously perform desired pattern formation. Play.

  Hereinafter, although embodiment of this invention is described in detail, this invention is not limited to these embodiment.

  In the present invention, an article having a resist material is, for example, a known resist material is applied on an article such as a semiconductor substrate or a glass substrate, and a predetermined resist pattern (resist film pattern) is formed by a normal photo process. In addition, there are those that have been subjected to various treatments such as etching. Here, the thickness of the resist material is not particularly limited, but a film thickness of about 0.1 to 5 μm is usually employed.

In the present invention, for example, referring to FIG. 1, first, a water-soluble or alkali-soluble material is formed on a substrate 10 such as a silicon wafer or on a low dielectric material film 11 such as a SiO ₂ film formed on the substrate 10. A layer 12 of polymer is formed. Next, a water-insoluble or non-alkaline polymer layer 13 is formed on the water-soluble or alkali-soluble polymer layer 12. The material of the water-insoluble or non-alkaline polymer layer 13 may be any material that does not intermix with the water-soluble or alkali-soluble polymer layer 12 and the resist film 14 formed on the water-insoluble or non-alkaline polymer layer 13. There is no particular limitation. In particular, the lower antireflection film layer generally used for resist films can be substituted as a water-insoluble or non-alkaline polymer layer. Next, a resist film 14 is applied / formed, and after exposure / development, etching is performed up to the layer (low dielectric material film 11) below the water-soluble or alkali-soluble polymer layer 12 to transfer the pattern.

  Then, after passing through the necessary steps, the wafer substrate with the resist material that is no longer needed is immersed in water or an alkaline solution, or water or an alkaline solution is applied while rotating the wafer substrate, and the water-soluble or By dissolving from the alkali-soluble polymer layer 12 and peeling off all the layers (13, 14) above the water-soluble or alkali-soluble polymer layer 12, a predetermined pattern is formed on the wafer substrate while removing the resist material. be able to.

  In the present invention, the water-soluble or alkali-soluble polymer layer 12 to be exposed on the side wall may be covered with a protective film by the etching process. In that case, after performing the ashing or chemical solution treatment that does not cause damage to the substrate and removing the protective film on the side wall, all the layers above the water-soluble or alkali-soluble polymer layer 12 may be peeled by the above process. I can do it.

  In the present invention, typical examples of the water-soluble or alkali-soluble polymer include those shown in JP-A-61-283610. Specifically, the general formula (I)

（式中、Ｒ¹、Ｒ²およびＲ³は、同一でも異なってもよく、水素原子またはアルキル基、好ましくは水素原子またはメチル基、エチル基、プロピル基、イソプロピル基、ブチル基、イソブチル基、第３ブチル基、ぺンチル基、イソぺンチル基、ネオペンチル基等のＣ₁〜Ｃ₅のアルキル基、特に好ましくはメチル基、エチル基、プロピル基、ブチル基、第３ブチル等のＣ₁〜Ｃ₄のアルキル基である。）で表わされる化合物、
および一般式（ＩＩ）

(Wherein R ¹ , R ² and R ³ may be the same or different and are each a hydrogen atom or an alkyl group, preferably a hydrogen atom or a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, tertiary butyl group, pentyl group, isopentyl group, an alkyl group of C ₁ -C _5, such as a neopentyl group, particularly preferably a methyl group, an ethyl group, a propyl group, a butyl group, C ₁ ~ such as tert-butyl A compound represented by C ₄ alkyl group),
And general formula (II)

（式中、Ｒ⁴は、水素原子またはアルキル基、好ましくは水素原子またはＣ₁〜Ｃ₅のアルキル基、特に好ましくは水素原子またはＣ₁〜Ｃ₃のアルキル基であり；Ｒ⁵は、水酸基を有するまたは有さないアルキレン基、好ましくはメチレン基、エチレン基、メチルエチレン基、エチルエチレン基、プロピルエチレン基、イソプロピルエチレン基、プロピレン基、１−メチルプロピレン基、２−メチルプロピレン基、１−エチルプロピレン基、２−エチルプロピレン基、ブチレン基、イソブチレン基、ペンチレン基、イソペンチレン基、ネオペンチレン基、ヒドロキシエチレン基、１−ヒドロキシプロピレン基、２−ヒドロキシプロピレン基等のＣ₁〜Ｃ₅の水酸基を有するまたは有さないアルキレン基、特に好ましくはエチレン基、メチルエチレン基、プロピレン基または２−メチルプロピレン基であり；Ｒ⁶、Ｒ⁷およびＲ⁸は同一でも異なってもよく、アルキル基、好ましくはＣ₁〜Ｃ₅のアルキル基、特に好ましくはＣ₁〜Ｃ₄のアルキル基であり；Ｘは、塩素原子、臭素原子、ヨウ素原子等のハロゲン原子、メチル硫酸基、エチル硫酸基等の低級アルキル硫酸基、好ましくはＣ₁〜Ｃ₃のアルキル硫酸基、または水酸基である）で表わされる化合物
を含む単量体混合物を重合してなる重合体を挙げることができる。

Wherein R ⁴ is a hydrogen atom or an alkyl group, preferably a hydrogen atom or a C ₁ -C ₅ alkyl group, particularly preferably a hydrogen atom or a C ₁ -C ₃ alkyl group; R ⁵ is a hydroxyl group Alkylene group having or not having, preferably methylene group, ethylene group, methylethylene group, ethylethylene group, propylethylene group, isopropylethylene group, propylene group, 1-methylpropylene group, 2-methylpropylene group, 1- ethylpropylene, 2-ethyl propylene, butylene, isobutylene, pentylene, isopentylene group, neopentylene group, hydroxy ethylene group, 1-hydroxypropylene group, the hydroxyl group of C ₁ -C _5, such as 2-hydroxy propylene group With or without alkylene group, particularly preferably ethylene group, methyl ethyl A Rene group, a propylene group or a 2-methylpropylene group; R ⁶ , R ⁷ and R ⁸ may be the same or different and are alkyl groups, preferably C ₁ -C ₅ alkyl groups, particularly preferably C _1- an alkyl group of C _4; X is a chlorine atom, a bromine atom, a halogen atom such as iodine atom, a methyl sulfate group, an ethyl a lower alkyl sulfate group such as sulfuric acid group, preferably an alkyl sulfate group of C ₁ -C _3, Or a polymer obtained by polymerizing a monomer mixture containing a compound represented by a hydroxyl group).

  Specific examples of the compound represented by the general formula (I) include N, N-dimethylacrylamide, N-methylacrylamide, N, N-diethylacrylamide, N, N-dipropylacrylamide, N-ethylacrylamide, and N-propyl. Acrylamide, N, N-diisopropylacrylamide, N, N-dibutylacrylamide, N-isopropylacrylamide, N-butylacrylamide, N, N-diisobutylacrylamide, N, N-di-t-butylacrylamide, N-isobutylacrylamide, N -Tertiary butylacrylamide, N, N-dipentylacrylamide, N, N-dimethylmethacrylamide, N-pentylacrylamide, N-methylmethacrylamide, N, N-diethylmethacrylamide, N, N-dipro Methacrylamide, N-ethyl methacrylamide, N-propyl methacrylamide, N, N-diisopropyl methacrylamide, N, N-dibutyl methacrylamide, N-isopropyl methacrylamide, N-butyl methacrylamide, N, N-diisobutyl methacryl Amides, N, N-ditertbutylmethacrylamide, N-isobutylmethacrylamide, N-tertbutylmethacrylamide, N, N-dipentylmethacrylamide, N-pentylmethacrylamide, N, N-dimethyl (α-ethyl) Examples thereof include acrylamide, N, N-dimethyl (α-propyl) acrylamide, N-methyl (α-butyl) acrylamide, N-butyl (α-isopropyl) acrylamide, and N-methylacrylic acid is particularly preferable. Rilamide, N-methylmethacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N-ethylacrylamide, N-ethylmethacrylamide, N, N-diethylacrylamide, N, N-diethylmethacrylamide, N -Tertiary butyl acrylamide, N-tertiary butyl methacrylamide, N, N-di-tertiary butyl acrylamide, N, N-di-tert butyl methacrylamide, etc.

  Specific examples of the compound represented by the general formula (II) include 2-acryloyloxyethyltrimethylammonium chloride, 2-acryloyloxyethyltriethylammonium chloride, 2-methacryloyloxyethyltrimethylammonium chloride, 2-methacrylic acid. Leuoxyethyltriethylammonium chloride, 3-acryloyloxypropyltrimethylammonium chloride, 3-acryloyloxypropyltriethylammonium chloride, 3-methacryloyloxypropyltrimethylammonium chloride, 3-methacryloyloxypropyltriethylammonium chloride, 2-acrylic Leuoxyethyltrimethylammonium promide, 2-acryloyloxyethyltriethylammonium promide, 2-methacrylo Roxyethyltrimethylammonium methylsulfate, 2-methacryloyloxyethyltriethylammonium promide, 3-acryloyloxypropyltrimethylammonium methylsulfate, 3-acryloyloxypropyltriethylammonium hydroxide, 3-methacryloyloxypropyltrimethylammonium Methyl sulfate, 3-methacryloyloxypropyl triethylammonium hydroxide, 2- (α-ethyl) acryloyloxyethyl trimethylammonium chloride, 3- (α-propyl) acryloyloxypropyl triethylammonium promide, 3- (Α-Isopropyl) acryloyloxypropyltripropylammonium iodide, 4-methacryloyloxybutyltrimethylammonium Examples include mu-zide, 4- (α-ethyl) acryloyloxybutyltripropylammonium chloride, 2-hydroxy-3-methacryloyloxypropyltrimethylammonium chloride, 5-acryloyloxypentyltributylammonium promide, and the like. Particularly preferred are 2-acryloyloxyethyltrimethylammonium chloride, 2-methacryloyloxyethyltrimethylammonium chloride, 2-acryloyloxyethyltrimethylammonium methylsulfate, 2-methacryloyloxyethyltrimethylammonium methylsulfate, 2-acryloyloxyethyl ethyl triethylammonium chloride, 2-methacryloyloxyethyl triethylammonium chloride, 3-acryloyloxy Propyltrimethylammonium chloride, 3-methacryloyloxypropyltrimethylammonium chloride, 3-acryloyloxypropyltrimethylammonium methylsulfate, 3-methacryloyloxypropyltrimethylammonium methylsulfate, 3-acryloyloxypropyltriethylammonium chloride, 3 -Methacryloyloxypropyl triethylammonium chloride etc. can be mentioned.

  The production of the polymer exhibits its effect by making the compounds represented by the general formulas (I) and (II) essential, but if necessary, in the general formulas (I) and (II) Third polymerizable monomers other than the represented compounds can be used, and specific examples of such polymerizable monomers include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, acrylic Acrylic acid or methacrylic acid esters such as butyl acrylate, butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tertiary butyl acrylate, tertiary butyl methacrylate, 2-ethylhexyl methacrylate, phenyl acrylate, phenyl methacrylate Vinyl aromas such as styrene, α-methylstyrene, p-methylstyrene, vinylnaphthalene Mention may be made of the compound. Of these polymerizable monomers, it is preferable to use acrylic acid or methacrylic acid alkyl ester in that the patterning characteristics during development when using the resulting polymer as a radiation curable composition are good. .

  The monomer mixture in the polymerization is preferably such that the proportion of the compound represented by the general formula (I) is 10 to 99% by weight, particularly 20 to 90% by weight. When the compound represented by the general formula (I) is less than 10% by weight, when the obtained polymer is prepared as a radiation curable composition, not only the sensitivity to radiation is lowered, but also the remaining film ratio during development. Is not preferable because of a low. On the other hand, when the amount of the compound represented by the general formula (I) is more than 99% by weight, the solubility of the resulting polymer in a solvent is lowered and workability is deteriorated.

  On the other hand, the proportion of the compound represented by the general formula (II) is preferably 1 to 90% by weight, particularly 10 to 80% by weight in the monomer mixture. When the proportion of the compound represented by the general formula (II) is less than 1% by weight, the dyeability of the resulting polymer is low, and when it is more than 90% by weight, the resulting polymer is used as a radiation curable composition. When prepared and used, it is not preferred because the composition swells greatly during development and the resolution decreases. When a polymerizable monomer other than the compounds represented by the general formulas (I) and (II) is used as the monomer mixture, the proportion of the polymerizable monomer in the monomer mixture is 50% by weight. % Or less, and particularly preferably 30% by weight or less. When the ratio of the polymerizable monomer exceeds 50% by weight, the solubility of the resulting polymer in a solvent becomes poor.

  Water-soluble or alkali-soluble polymers include monomers such as N, N-dimethylacrylamide, N-methylacrylamide, N, N-diethylacrylamide, methacryloyloxyethyltrimethylammonium chloride, acryloyloxyethyltrimethylammonium chloride, Polymers with monomers such as acryloyloxyethyl triethylammonium chloride are preferred.

  The water-insoluble polymer used in the water-insoluble or non-alkali-soluble polymer layer in the present invention includes, as described above, a water-soluble or alkali-soluble polymer layer and a resist film formed on the water-insoluble or non-alkaline polymer layer. As long as the material does not intermix, the photosensitive polymer is preferable because it is necessary to dissolve and remove the portion by exposure and development through a mask. Further, the lower antireflection film generally used for resist films can be substituted as a water-insoluble or non-alkaline polymer layer.

  Examples of resist film materials include a positive resist material composed of an alkali-soluble resin and a quinonediazide-based photosensitizer, a negative resist material composed of an alkali-soluble resin and a radiation-sensitive crosslinking agent, and a radiation-sensitive acid generator. And a positive or negative chemically amplified resist material.

  And in this invention, after forming a resist film on a water-insoluble or non-alkaline polymer layer, the exposure development process which develops the exposed resist film after selectively exposing with a radiation through a mask is performed. . The radiation used for exposure is appropriately selected from visible light, ultraviolet light, far ultraviolet light, X-rays and the like according to the type of resist used. Examples of the developer used for development include an alkaline aqueous solution in which sodium hydroxide, potassium hydroxide, diethylamine and the like are dissolved.

Hereinafter, the present invention will be specifically described with reference to examples.
First, a water-soluble polymer composition and a resist composition were prepared as follows.

1. Preparation of water-soluble polymer composition A three-necked flask equipped with a stirrer and a thermometer was purged with nitrogen, 86 g of N, N-dimethylacrylamide, 14 g of methacryloyloxyethyltrimethylammonium chloride, 300 ml of methanol, and azobisisobutyronitrile. 3 g was charged and polymerized at 60 ° C. for 8 hours. The reaction solution was poured into 1 liter of ethyl acetate to precipitate the produced polymer. The polymer was filtered off, further washed with ethyl acetate, and then dried at 60 ° C. under vacuum to obtain 50 g of a white powdery polymer. 10 g of this polymer was dissolved in 90 g of water, and 0.2 g of sodium 4,4′-diazidostilbene-2,2′-disulfonate was added to obtain a uniform solution. This was filtered through a membrane filter having a pore size of 0.2 μm to prepare a water-soluble polymer composition solution.

2. Preparation of Resist Composition Triphenylsulfonium triflate as an acid generator is added to an alicyclic acrylic resin generally used in ArF positive resists, and dissolved in 2-heptanone to obtain a uniform solution. The solution was filtered through a 2 μm membrane filter to prepare a resist composition.

Example 1:
As shown in FIG. 1, after the SiO ₂ film 11 is formed on the silicon wafer substrate 10, the water-soluble polymer composition prepared as described above is applied onto the SiO ₂ film so that the film thickness becomes 2000 nm. And baked at 205 ° C. for 1 minute to form a water-soluble polymer layer 12. Next, on the water-soluble polymer layer 12, a commercially available non-water-soluble and non-alkali-soluble polymer anti-reflection film forming composition was applied and baked to form an anti-reflection film layer 13. . Furthermore, the resist composition prepared as described above was applied thereon so that the film thickness after baking was 2000 nm, and baked at 130 ° C. for 1 minute to form a resist film 14.

Next, 193 nm radiation was exposed through a photomask at 20 mJ / cm ² and developed with a 2.38 wt% aqueous solution of tetramethylammonium hydroxide for 30 seconds to obtain a substrate with a pattern.
Thereafter, the antireflective film layer 13 and the water-soluble polymer layer 12 were etched by O ₂ plasma treatment, and then the SiO ₂ film 11 was etched by fluorine gas to obtain a substrate having a structure as shown in FIG. Then, rinsing with water was performed for 100 seconds while rotating the substrate. As a result, all the films above the SiO ₂ film 11 were peeled off.

Example 2:
As shown in FIG. 2, after forming a carbon-containing SiO ₂ film 21, which is one of low dielectric constant (low-k) films, on a silicon wafer substrate 20, the above-mentioned water-soluble polymer composition has a thickness of 2000 nm. And then baked at 205 ° C. for 1 minute to form a water-soluble polymer layer 22. Next, on the water-soluble polymer layer 22, the same antireflection film-forming composition as used in Example 1 was applied and baked to form the antireflection film layer 23. The resist composition was applied so that the film thickness after baking was 2000 nm and baked at 130 ° C. for 1 minute to form a resist film 24.

Next, in the same manner as in Example 1, exposure and development were performed to obtain a substrate with a pattern.
Thereafter, the antireflection film layer 23 and the water-soluble polymer layer 22 were etched by O ₂ plasma treatment, and then the carbon-containing SiO ₂ film layer 21 was etched by fluorine gas to obtain a substrate having a structure as shown in FIG. . Then, when the substrate was rotated and rinsed with water for 100 seconds, the film above the carbon-containing SiO ₂ film was peeled off.

  The present invention is not limited to its use as long as it is an article that etches a pattern made of a resist material and transfers the pattern, and in particular, in the manufacture of semiconductor devices, the resist material that is no longer necessary on the wafer substrate is used. It is preferably employed for removal.

It is sectional drawing which shows one Embodiment of the pattern formation on a wafer substrate. It is sectional drawing which shows other embodiment of pattern formation on a wafer substrate.

Explanation of symbols

10 ... silicon wafer substrate, 11 ... low-dielectric material film (SiO ₂ film), 12 ... water-soluble or alkali-soluble polymer layer, 13 ... water-insoluble or non-alkaline polymer layer (antireflection film layer), 14 ... resist film, 20 ... silicon wafer substrate, 21 ... carbon-containing SiO ₂ film, 22 ... water-soluble polymer layer, 23 ... antireflection film layer, 24 ... resist film.

Claims (5)

(I) forming a water-soluble or alkali-soluble polymer layer on the substrate;
(Ii) forming a water-insoluble or alkali-soluble polymer layer on the water-soluble or alkali-soluble polymer layer;
(Iii) forming a resist film on the water-insoluble or non-alkali-soluble polymer layer;
(Iv) a step of exposing and developing after the step (iii);
(V) etching a layer below the water-soluble or alkali-soluble polymer layer;
(Vi) removing all the upper layer including the water-soluble or alkali-soluble polymer layer with water or an alkali solution;
A pattern forming method including:   The pattern formation method according to claim 1, wherein a low dielectric material film is formed on the substrate, and a water-soluble or alkali-soluble polymer layer is formed thereon.   The pattern formation method according to claim 1, wherein an antireflection film layer is formed between the water-soluble or alkali-soluble polymer layer and the water-insoluble or non-alkali-soluble polymer layer.   The pattern formation method according to claim 1, wherein the water-insoluble or non-alkali-soluble polymer layer also serves as an antireflection film layer.   The water-soluble or alkali-soluble polymer is a monomer selected from N, N-dimethylacrylamide, N-methylacrylamide, and N, N-diethylacrylamide, methacryloyloxyethyltrimethylammonium chloride, and acryloyloxy. The pattern formation method according to any one of claims 1 to 4, which is a polymer with any one of ethyltrimethylammonium chloride and acryloyloxyethyltriethylammonium chloride.

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