WO2005091347A1 - SiN FILM SELECTIVE ETCHING SOLUTION AND ETCHING METHOD - Google Patents

SiN FILM SELECTIVE ETCHING SOLUTION AND ETCHING METHOD Download PDF

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Publication number
WO2005091347A1
WO2005091347A1 PCT/JP2005/004494 JP2005004494W WO2005091347A1 WO 2005091347 A1 WO2005091347 A1 WO 2005091347A1 JP 2005004494 W JP2005004494 W JP 2005004494W WO 2005091347 A1 WO2005091347 A1 WO 2005091347A1
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Prior art keywords
ether
solvent
etching solution
etching
mass
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PCT/JP2005/004494
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French (fr)
Japanese (ja)
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Mitsushi Itano
Daisuke Watanabe
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Daikin Industries, Ltd.
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Publication of WO2005091347A1 publication Critical patent/WO2005091347A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
    • H01L21/3105—After-treatment
    • H01L21/311—Etching the insulating layers by chemical or physical means
    • H01L21/31105—Etching inorganic layers
    • H01L21/31111—Etching inorganic layers by chemical means
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K13/00—Etching, surface-brightening or pickling compositions
    • C09K13/04—Etching, surface-brightening or pickling compositions containing an inorganic acid
    • C09K13/08—Etching, surface-brightening or pickling compositions containing an inorganic acid containing a fluorine compound

Definitions

  • the present invention relates to a technique for selectively etching a SiN film formed on a Si substrate, a compound semiconductor substrate, or a glass substrate for a liquid crystal display, and more particularly, to a substrate including a SiON film together with a SiN film. And technology for selectively etching a SiN film.
  • a semiconductor processing process includes a step of selectively removing a certain material with respect to another material.
  • SiN films formed by various CVD methods and SiO films formed by various CVD methods and thermal oxidation methods are generally used as insulating films in various applications.
  • it may be required to selectively etch the SiN film.
  • As an etching method there are wet etching and dry etching. To remove other films without damaging them, a wet etching method is used.
  • a method of wet etching a SiN film generally uses hot phosphoric acid! (Patent Documents 1 and 2).
  • the SiN film can be etched at an etching rate of 100 A / min and the etching rate selectivity of the SiN film and the SiO film can be as high as 100: 1.
  • hot phosphoric acid requires treatment at a high temperature of 140 ° C-180 ° C. At low temperatures below 100 ° C, the SiN film is hardly etched.
  • P (phosphorus) may contaminate the clean room atmosphere, and an alternative process is desired.
  • Patent Document 3 a method of removing a SiN film by using a mixed solution of V or any one of ethylene glycol, glycerol, and diethylene glycol dimethyl ether and dilute hydrofluoric acid is known (Patent Document 3). Using this liquid mixture enables etching at a low temperature (100 ° C. or lower). However, ethylene glycol and water used in Patent Document 3 are not applied as a highly selective etching solution having a very low etching selectivity as shown in Comparative Examples described later (Patent Document 4).
  • Patent Document 1 JP-A-9 45660
  • Patent Document 2 Japanese Patent Application Laid-Open No. 2002-246378
  • Patent Document 3 US Patent 4,269,654
  • Patent Document 4 US Patent No. 3607480
  • An object of the present invention is to achieve etching at a low temperature (100 ° C. or lower) and to etch a SiN film without etching an SiO film! “Highly selective etching chemical for SiN film” and “SiN film” To provide a high selective etching method.
  • the present invention provides a method of forming a SiN film formed on a substrate at a low temperature of 100 ° C or lower using a mixed solution containing hydrogen fluoride, an ether-based solvent, and, if necessary, water. Can be selectively etched with respect to a SiO film, a Si film or a Si substrate, particularly a SiO film.
  • the present invention specifically provides the following etching solution and etching method.
  • An etchant for selectively etching a SiN film containing hydrogen fluoride, an ether-based solvent and a Z or fluorinated ether-based solvent, and if necessary, water.
  • the content of ether solvents and Z or fluorinated ether solvents is 99.9-160% by mass, the content of hydrogen fluoride (HF) is 0.1-30% by mass, and the content of water is 10% by mass or less.
  • Item 4 The etching solution according to any one of Items 1 to 3.
  • the content of ether solvent and / or fluorinated ether solvent is 90-70% by mass, hydrogen fluoride (HF) content is 10-30% by mass, and water content is 10% by mass or less.
  • HF hydrogen fluoride
  • the content of ether solvent and Z or fluorinated ether solvent is 99.9-90% by mass, hydrogen fluoride (HF) content is 0.1-10% by mass, and water content is 3% by mass or less.
  • Item 4. The etching solution according to any one of Items 1 to 3.
  • a substrate including a SiON film together with a SiN film is etched at a temperature of 100 ° C. or less using the etching solution described in any one of Items 1 to 13 above. How to ching.
  • a SiN film formed on a SiO film can be selectively etched at a low temperature of 100 ° C. or less on a substrate such as a semiconductor substrate or a glass substrate.
  • ether solvent and Z or a fluorinated ether solvent may be simply referred to as an ether solvent.
  • ether solvents examples include ethylene glycol dimethyl ether (monoglyme), diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl enoate ether (triglyme), 1,2-diethoxyxetane, 1,2-dipropoxyxetane, and dioxo.
  • Sun tetrahydrofuran and the like.
  • formula (1) or (2) the following formula (1) or (2)
  • R and R are the same or different and each have a C 1 -C linear or branched lower alkyl group m 14
  • n an integer of 0-4.
  • Examples of the lower alkyl group having the following include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl, preferably methyl, ethyl, n-propyl, isopropyl, and more preferably Is methyl or ethyl, especially methyl.
  • n is an integer of 0-4, preferably an integer of 1-3.
  • ether solvents include (mono-, di-, tri-, tetra-) ethylene glycol dimethyl ether, (mono-, di-, tri-, tetra-) ethylene glycol getyl ether, (mono-, di, tri, tetra-) ethylene glycol di-n- Propyl ether, (mono, di, tri, tetra) ethylene glycol diisopropyl ether, (mono, di, tri, tetra) ethylene glycol di-n-butyl ether, (mono, di, tri, tetra) ethylene glycol diisobutyl ether , (Mono, di, tri, tetra) ethylene glycol di sec-butyl ether, (mono, di, tri, tetra) ethylene glycol ditert-butyl ether, etc., ethylene glycol ether solvents, (mono, di, etc.) , Tri, tetra) propylene
  • the fluorinated ether-based solvent means a solvent obtained by substituting one or more hydrogen atoms and S fluorine atoms in the above-mentioned ether-based solvents, and the fluorine atom is a difference between the alkylene glycol portion and the alkyl ether portion. , Have been introduced, may be.
  • the fluorinated ether solvent is represented by the general formula (If) or (2f):
  • Rf and Rf are the same or different
  • nl represents an integer of 0-4.
  • Rf and Rf contains a fluorine atom
  • nl is an integer of 0-4, preferably an integer of 0-3.
  • n2 is an integer of 0-4, preferably an integer of 0-3.
  • the fluorinated ether solvent has a low toxicity ⁇ C F OCH (trade name "HE-7100”)
  • ethylene daryl glycol dimethyl ether (monoglyme)
  • a high molecular ether solvent such as triethylene glycol dimethyl ether (triglyme) has a high flash point (100 ° C. or higher), and is therefore a preferred solvent from the viewpoint of safety.
  • Patent Document 3 A method of selectively etching a SiN film using a mixed solution of an organic solvent and hydrofluoric acid has been reported (Patent Document 3).
  • This organic solvent has a hydroxyl group.
  • Solvent On the other hand, the raw material organic solvent used in the present invention is characterized in that all the oxygen atoms are esterified, there is no alcoholic or phenolic hydroxyl group, and the ether solvent is a fluorinated ether solvent. Different in that. As shown in the comparative examples of the present specification, the presence of a hydroxyl group has a drawback that the selectivity of the SiN film is reduced.
  • the fluorinated ether-based solvent may be fluorinated to form an alkyl group (Rf m
  • Rf may be a perfluoroalkyl group.
  • the organic solvent containing the compound is not flammable irrespective of whether the alkylene glycol moiety is fluorinated or not, and is therefore preferred from the viewpoint of safety.
  • the etching solution is a solvent in which the ether solvents mentioned above are mixed, and hydrogen fluoride (
  • fluorinated ether-based solvent is mixed with hydrofluoric acid containing water in the composition, it is preferable to use the fluorinated ether-based solvent by mixing with another ether-based solvent from the viewpoint of compatibility with water.
  • the content of the ether solvent and Z or fluorinated ether solvent etching solution of the present invention is usually 99.9 one 60.0 wt%, preferably 99.9 one 70.0% by weight, more preferably 99.9 one 80.0 mass 0/0 It is.
  • the concentration of hydrogen fluoride (HF) contained in the mixed solution is preferably high (for example, 10 to 30% by mass, more preferably 10 to 20% by mass) when the SiN film is etched at a high speed.
  • a low concentration for example, 0.1 to 10% by mass, more preferably 0.1 to 5% by mass is preferable.
  • water is an optional component and may be contained, but may not be contained at all.
  • the water content is usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, further preferably 2% by mass, still more preferably 1% by mass or less, and most preferably 0.5% by mass or less. % Or less. Further, the content of water may be 0% by mass.
  • the concentration of water contained in the etching solution is preferably low when the SiN film is highly selectively etched, and more preferably there is no water at all. Also, when the moisture concentration increases, the etching rate of the SiN film and the SiO film increases, and when the moisture concentration increases too much, the etching rate of the SiO film may be faster than the etching rate of the SiN film. Therefore, the moisture concentration It is possible to adjust the selectivity by adjusting.
  • etching temperature increases the etching rate.
  • the etching selectivity of the SiN film tends to be improved. Therefore, it is preferable to increase the etching temperature in order to increase the etching rate and the selectivity of the SiN film to the SiO film.
  • the temperature is too high, single-wafer processing becomes difficult, and HF gas is released.
  • the required etching rate ratio and etching rate can be adjusted by temperature.
  • a preferred etching temperature is 100 ° C or lower, preferably 20 to 80 ° C, more preferably 20 to 50 ° C, and still more preferably 20 to 30 ° C.
  • the temperature is preferably 100 ° C. or lower.
  • the time required to raise the temperature of the chemical can be shortened, and the temperature control and management are easy.
  • the etching time is generally 0.05-5 minutes, preferably 0.1-2 minutes.
  • the etching method of the present invention includes a method of applying and spraying an etching solution on a substrate to be processed, a method of dipping the substrate in the etching solution, and the like.
  • the above-mentioned SiN film can be formed by various CVD methods of plasma, heat, light, laser, and ion beam. Commonly used methods are the low pressure CVD (LP-CVD) method of the plasma CVD method and the thermal CVD method.
  • LP-CVD low pressure CVD
  • the SiO film described above includes a Si substrate, a thermally oxidized SiO film obtained by thermally oxidizing a Si film,
  • SiO films includes SiO films, chemical SiO films chemically reacted with nitric acid, sulfuric acid, etc., Si substrates, natural oxide films of Si films, and TEOS films formed by various CVD methods of plasma, heat, light, laser, and ion beam.
  • the SiO film does not include a film doped with impurities of BPSG, BSG and AsSG containing boron (B), phosphorus (P) and arsenic (As).
  • the etching solution of the present invention usually has an etching selection ratio of ⁇ SiN film etching speed Z (SiO film etching speed) ⁇ of SiN film of LP-CVD method and SiO film of thermal oxidation method. It is 3 or more, preferably 1.5 or more, more preferably 2.0 or more, still more preferably 2.5 or more, and especially 3 or more.
  • the etchant of the present invention not only selectively etches the SiN film with respect to the SiO film, but also
  • the silicon film or the Si substrate is also selectively etched.
  • the selectivity of the etching solution of the present invention to a Si film or a Si substrate is as follows.
  • the etching selectivity of the SiN film and the Si film ⁇ (etching speed of the SiN film) Z (etching speed of the Si film) ⁇ is usually 10 or more, preferably 100 or more, and more preferably the Si film is completely etched. Preferably not.
  • the etching selectivity of the SiN film and the Si substrate ⁇ (etching rate of the SiN film) / (etching rate of the Si substrate) ⁇ is usually 10 or more, preferably 100 or more, and more preferably the Si substrate is completely etched. What is preferred.
  • examples of the SiN film and the SiO film include a semiconductor substrate, a glass substrate for a display such as a liquid crystal display, a Si substrate, a SiC substrate, and a compound semiconductor substrate such as GaAs, InP, and GaP.
  • a method for preparing an anhydrous etching solution comprising hydrogen fluoride and an ether solvent and Z or a fluorinated ether solvent is as follows. There are a method of absorbing hydrogen fluoride gas into the above ether solvent and Z or a fluorinated ether solvent, and a method of mixing hydrogen fluoride at a temperature of 20 ° C or less and mixing with a liquid. Either method may be used.
  • the hydrous etching solution is prepared by mixing hydrofluoric acid with an ether-based solvent and Z or a fluorinated ether-based solvent to form an etching solution, and forming the hydrogen fluoride and the ether-based solvent and Z or fluorinated ether as described above. Water may be added to the mixture of the system solvents.
  • an etching solution of the present invention is prepared by mixing hydrofluoric acid and an ether-based solvent.
  • the etching solution may be a mixture of hydrogen fluoride or hydrofluoric acid and an ether-based solvent and a solvent containing Z or a fluorinated ether-based solvent.
  • Other surfactants, chelating agents, and anticorrosives may be mixed. .
  • the compounding amount of other components is suppressed to less than 10% by mass.
  • Table 1 shows the etching rates of the etching solution of the present invention, which also has hydrogen fluoride and ether-based solvent power, and the mixed solution composed of a solvent having a hydroxyl group described in Patent Document 3 and hydrogen fluoride. Is shown. The etching characteristics under the same hydrogen fluoride concentration (ma SS %) and the same temperature conditions are shown. As shown in Table 1, as the number of hydroxyl groups becomes 2 ⁇ 1 ⁇ 0 (ethylene glycol ⁇ ethylene glycol monobutyl ether ⁇ ethylene glycol dimethyl ether / comparative example 2 ⁇ comparative example 1 ⁇ example 4), the etching rate selectivity increases. This shows that the mixture is higher, indicating that the mixture of ether-based solvent and HF is superior to the mixture of organic solvent and hydrogen fluoride reported in the literature.
  • Table 2 shows that hydrogen fluoride and ethylene glycol dimethyl ether
  • the etching rate and selectivity of the SiN film by the LP-CVD method and the SiO film by the thermal oxidation method are shown with respect to the partial concentration. As the water concentration increases, the etching rates of the SiN film and the SiO film tend to increase, and the selective etching property of the SiN film tends to decrease.
  • dilute hydrofluoric acid in which water is contained in hydrogen fluoride may be used.
  • water is contained, and only anhydrous hydrogen fluoride is used.
  • the effect of increasing the etching rate due to the increase in the water concentration in the chemical solution is greater than that of the iN film formed by the SiO film. Therefore, it is possible to etch the SiO film and SiN at a constant speed by adjusting the moisture concentration.
  • Table 2 shows the dependence of the water concentration in a mixed solution of hydrogen fluoride and ethylene glycol dimethyl ether at 60 ° C. on the etching rate and the rate selectivity of the SiN film of the LP-CVD method and the SiO of the thermal oxidation method. Show.
  • Table 3 shows the ratio of the etching rate to the etching rate when the concentration of hydrogen fluoride contained in the mixture was changed.
  • a high concentration is preferable.
  • a low concentration is preferable.
  • Table 3 shows the dependence of the etching rate and the etching rate selectivity on the etching temperature.
  • the temperature of the mixed solution of hydrogen fluoride and ethylene glycol dimethyl ether increases, the etching rate of the SiN film and the SiO film increases.
  • the etching rate ratio tends to increase. Therefore, the etching rate and the selectivity can be adjusted by the etching temperature.
  • the etching rate of the SiN film is 71 A / min, and the selectivity is 23. Is obtained. It has become clear that SiN films can be etched with a higher selectivity than conventional etchants.

Abstract

There is provided a method of performing selective low-temperature wet etching of an SiN film against an SiO film and Si. Further, there is provided a solution for selective etching of an SiN film, comprising hydrogen fluoride, an ether solvent and/or a fluorinated ether solvent optionally together with water.

Description

明 細 書  Specification
SiN膜の選択エッチング液及びエッチング方法  Selective etching solution and etching method for SiN film
技術分野  Technical field
[0001] 本発明は、 Si基板、化合物半導体基板や、液晶表示用のガラス基板上に成膜され ている SiN膜の選択的エッチング技術に関し、詳しくは、 SiN膜とともに SiO膜を含む基 板において、 SiN膜を選択的にエッチングする技術に関する。  The present invention relates to a technique for selectively etching a SiN film formed on a Si substrate, a compound semiconductor substrate, or a glass substrate for a liquid crystal display, and more particularly, to a substrate including a SiON film together with a SiN film. And technology for selectively etching a SiN film.
背景技術  Background art
[0002] 半導体の加工プロセスは、ある材料を他の材料に対して選択的に除去する工程を 含んでいる。半導体デバイスにおいて、一般的に各種 CVD法により成膜された SiN膜 、各種 CVD法、熱酸ィ匕法で成膜された SiO膜は絶縁膜として様々な用途に用いられ ている。この加工プロセスにおいて、 SiN膜を選択的にエッチングすることが求められ る場合がある。エッチング方法として、ウエットエッチングとドライエッチングがある。他 の膜にダメージを与えずきれいに取り除くには、ウエットエッチング方法が用いられて いる。  [0002] A semiconductor processing process includes a step of selectively removing a certain material with respect to another material. In semiconductor devices, SiN films formed by various CVD methods and SiO films formed by various CVD methods and thermal oxidation methods are generally used as insulating films in various applications. In this processing process, it may be required to selectively etch the SiN film. As an etching method, there are wet etching and dry etching. To remove other films without damaging them, a wet etching method is used.
[0003] これまで、 SiN膜をウエットエッチングする方法は、一般的に、熱燐酸を用いて!/、た（ 特許文献 1、 2)。 SiN膜を 100 A/minのエッチング速度でかつ、 SiN膜、 SiO膜のエッチ ング速度選択比は、 100 : 1と高選択にエッチングすることが可能である。しかし、熱燐 酸では、温度 140°C— 180°Cの高温での処理が必要である。 100°C以下の低温では、 SiN膜はほとんどエッチングされない。また、 P (燐）がクリーンルーム雰囲気を汚染す る怖れがあり、代替プロセスが望まれている。  [0003] Until now, a method of wet etching a SiN film generally uses hot phosphoric acid! (Patent Documents 1 and 2). The SiN film can be etched at an etching rate of 100 A / min and the etching rate selectivity of the SiN film and the SiO film can be as high as 100: 1. However, hot phosphoric acid requires treatment at a high temperature of 140 ° C-180 ° C. At low temperatures below 100 ° C, the SiN film is hardly etched. In addition, P (phosphorus) may contaminate the clean room atmosphere, and an alternative process is desired.
[0004] また、エチレングリコール、グリセロール、ジエチレングリコールジメチルエーテルの V、ずれか一つと希フッ酸の混合液を用いることで SiN膜を除去する方法が知られて ヽ る（特許文献 3)。この混合液を用いると低温（100°C以下)でエッチングが可能である 。しかし、特許文献 3で用いられているエチレングリコール、水は、後述の比較例に示 されるようにエッチング選択比は非常に低ぐ高選択エッチング液としては適用されて いない（特許文献 4)。  [0004] Also, a method of removing a SiN film by using a mixed solution of V or any one of ethylene glycol, glycerol, and diethylene glycol dimethyl ether and dilute hydrofluoric acid is known (Patent Document 3). Using this liquid mixture enables etching at a low temperature (100 ° C. or lower). However, ethylene glycol and water used in Patent Document 3 are not applied as a highly selective etching solution having a very low etching selectivity as shown in Comparative Examples described later (Patent Document 4).
特許文献 1：特開平 9 45660号公報 特許文献 2：特開 2002— 246378号公報 Patent Document 1: JP-A-9 45660 Patent Document 2: Japanese Patent Application Laid-Open No. 2002-246378
特許文献 3：米国特許 4269654  Patent Document 3: US Patent 4,269,654
特許文献 4：米国特許 3607480  Patent Document 4: US Patent No. 3607480
発明の開示  Disclosure of the invention
発明が解決しょうとする課題  Problems to be solved by the invention
[0005] 本発明の目的は、低温（100°C以下)でエッチングが実現でき、 SiO膜をエッチングし な!、で SiN膜をエッチングする" SiN膜を高選択エッチング薬液"及び、 "SiN膜を高選 択エッチングする方法"を提供することである。 課題を解決するための手段 An object of the present invention is to achieve etching at a low temperature (100 ° C. or lower) and to etch a SiN film without etching an SiO film! “Highly selective etching chemical for SiN film” and “SiN film” To provide a high selective etching method. Means for solving the problem
[0006] 本発明は、基板上に成膜されている SiN膜を、フッ化水素とエーテル系溶媒、さらに 必要に応じて水を含む混合液を用いて、 100°C以下の低温で SiN膜を、 SiO膜、 Si膜 或いは Si基板、特に SiO膜に対して選択的にエッチングできることを特徴とする。 [0006] The present invention provides a method of forming a SiN film formed on a substrate at a low temperature of 100 ° C or lower using a mixed solution containing hydrogen fluoride, an ether-based solvent, and, if necessary, water. Can be selectively etched with respect to a SiO film, a Si film or a Si substrate, particularly a SiO film.
[0007] 本発明は、具体的には以下のエッチング液及びエッチング方法を提供するもので ある。 The present invention specifically provides the following etching solution and etching method.
1. フッ化水素、エーテル系溶媒及び Z又はフッ素化エーテル系溶媒、必要に応じ てさらに水を含む、 SiN膜を選択的にエッチングするエッチング液。  1. An etchant for selectively etching a SiN film, containing hydrogen fluoride, an ether-based solvent and a Z or fluorinated ether-based solvent, and if necessary, water.
2. 水の含有量がエッチング液の 10質量％以下である項 1に記載のエッチング液 2. The etching solution according to item 1, wherein the water content is 10% by mass or less of the etching solution.
3. 実質的に水を含まない項 1又は 2に記載のエッチング液。 3. The etching solution according to item 1 or 2, which is substantially free of water.
4. エーテル系溶媒及び Z又はフッ素化エーテル系溶媒の含有量は、 99.9一 60質 量％、フッ化水素（HF)の含有量が 0.1— 30質量％、水の含有量が 10質量％以下で ある項 1一 3のいずれかに記載のエッチング液。  4. The content of ether solvents and Z or fluorinated ether solvents is 99.9-160% by mass, the content of hydrogen fluoride (HF) is 0.1-30% by mass, and the content of water is 10% by mass or less. Item 4. The etching solution according to any one of Items 1 to 3.
5. エーテル系溶媒及び/又はフッ素化エーテル系溶媒の含有量は、 90— 70質量 %、フッ化水素（HF)の含有量が 10— 30質量％、水の含有量が 10質量％以下であ る項 1一 3のいずれかに記載のエッチング液。  5. The content of ether solvent and / or fluorinated ether solvent is 90-70% by mass, hydrogen fluoride (HF) content is 10-30% by mass, and water content is 10% by mass or less. An etching solution according to any one of Items 1-3.
6. エーテル系溶媒及び Z又はフッ素化エーテル系溶媒の含有量は、 99.9一 90質 量％、フッ化水素（HF)の含有量が 0.1— 10質量％、水の含有量が 3質量％以下であ る項 1一 3のいずれかに記載のエッチング液。  6. The content of ether solvent and Z or fluorinated ether solvent is 99.9-90% by mass, hydrogen fluoride (HF) content is 0.1-10% by mass, and water content is 3% by mass or less. Item 4. The etching solution according to any one of Items 1 to 3.
7. エーテル系溶媒及び Z又はフッ素化エーテル系溶媒力 グリコールジエーテル 系溶媒である項 1一 3のいずれかに記載のエッチング液。 7. Ether solvent and Z or fluorinated ether solvent Glycol diether Item 4. The etching solution according to any one of Items 1 to 3, which is a system solvent.
8. グリコールジエーテル系溶媒力 エチレングリコールジメチルエーテル（モノグラ ィム）である項 7に記載のエッチング液。  8. Glycol diether solvent power The etching solution according to item 7, which is ethylene glycol dimethyl ether (monochrome).
9. グリコールジエーテル系溶媒力 トリエチレングリコールジメチルエーテル（トリグ ライム)である項 7に記載のエッチング液。  9. The etching solution according to item 7, wherein the etching solution is triethylene glycol dimethyl ether (triglyme).
10. グリコールジエーテル系溶媒力 ジエチレングリコールジメチルエーテル（ジグ ライム)である項 7に記載のエッチング液。  10. Glycol diether-based solvent power The etching solution according to item 7, which is diethylene glycol dimethyl ether (diglyme).
11. グリコールジエーテル系溶媒力 ジエチレングリコールジェチルエーテルであ る項 7に記載のエッチング液。  11. The etching solution according to item 7, which is a glycol diether solvent power diethylene glycol getyl ether.
12. エーテル系溶媒及び Z又はフッ素化エーテル系溶媒力 パーフルォロエーテ ル系溶媒である項 1一 3のいずれかに記載のエッチング液。  12. The etching solution according to any one of Items 13 to 13, which is an ether solvent and a Z or fluorinated ether solvent solvent.
13. エーテル系溶媒及び Z又はフッ素化エーテル系溶媒力 C F OCH及び  13. Ether solvent and Z or fluorinated ether solvent C F OCH and
4 9 3 Z又 は CF CH OCF CHFである項 1  4 9 3 Z or CF CH OCF Item 1 that is CHF
2 一 3のいずれかに記載のエッチング液。  23. The etching solution according to any one of items 1-3.
3 2 2  3 2 2
14. SiN膜とともに SiO膜を含む基板を、項 1一 13のいずれか〖こ記載のエッチング液 を用いて 100°C以下の温度でエッチングすることを特徴とする、 SiN膜を選択的にエツ チングする方法。  14. A substrate including a SiON film together with a SiN film is etched at a temperature of 100 ° C. or less using the etching solution described in any one of Items 1 to 13 above. How to ching.
15. 前記基板が半導体基板又はガラス基板である項 14に記載の方法。  15. The method according to item 14, wherein the substrate is a semiconductor substrate or a glass substrate.
16. エッチング温度が 20— 50°Cである項 14又は 15に記載の方法。  16. The method according to item 14 or 15, wherein the etching temperature is 20 to 50 ° C.
17. エッチング温度が 20— 30°Cである項 16に記載の方法。  17. The method according to item 16, wherein the etching temperature is 20 to 30 ° C.
発明の効果  The invention's effect
[0008] 本発明によれば、半導体基板、ガラス基板などの基板上に、 SiO膜上に成膜されて いる SiN膜を 100°C以下の低温でかつ選択的にエッチングすることができる。  According to the present invention, a SiN film formed on a SiO film can be selectively etched at a low temperature of 100 ° C. or less on a substrate such as a semiconductor substrate or a glass substrate.
発明を実施するための最良の形態  BEST MODE FOR CARRYING OUT THE INVENTION
[0009] 本明細書において、「エーテル系溶媒及び Z又はフッ素化エーテル系溶媒」を単 にエーテル系溶媒と記載することがある。  [0009] In this specification, the term "ether solvent and Z or a fluorinated ether solvent" may be simply referred to as an ether solvent.
上記のエーテル系溶媒としては、エチレングリコールジメチルエーテル（モノグライム） 、ジエチレングリコールジメチルエーテル（ジグライム）、トリエチレングリコールジメチ ノレエーテノレ（トリグライム）、 1, 2—ジエトキシェタン、 1, 2—ジプロポキシェタン、ジォキ サン、テトラヒドロフラン等が挙げられる。特に、下記式（1)または（2) Examples of the above ether solvents include ethylene glycol dimethyl ether (monoglyme), diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl enoate ether (triglyme), 1,2-diethoxyxetane, 1,2-dipropoxyxetane, and dioxo. Sun, tetrahydrofuran and the like. In particular, the following formula (1) or (2)
R - 0- (C H -0)n-R (1)  R-0- (C H -0) n-R (1)
m 2 4 1  m 2 4 1
または  Or
R - 0- (C H -0)n-R (2)  R-0- (C H -0) n-R (2)
m 3 6 1  m 3 6 1
(式中、 R、 Rは同一又は異なって C一 Cの直鎖又は分枝を有する低級アルキル基 m l 1 4  (Wherein, R and R are the same or different and each have a C 1 -C linear or branched lower alkyl group m 14
を示す、 nは 0— 4の整数を示す。 ) And n represents an integer of 0-4. )
で表されるエーテル系溶媒が挙げられる。 R、 Rで表される C一 Cの直鎖又は分枝 m l 1 4 And an ether-based solvent represented by R, C-C straight-chain or branched m l 14
を有する低級アルキル基としては、メチル、ェチル、 n—プロピル、イソプロピル、 n—ブ チル、イソブチル、 sec—ブチル、 tert—ブチルが挙げられ、好ましくはメチル、ェチル 、 n—プロピル、イソプロピル、より好ましくはメチルまたはェチル、特にメチルが挙げら れる。 nは、 0— 4の整数、好ましくは 1一 3の整数である。 Examples of the lower alkyl group having the following include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl, preferably methyl, ethyl, n-propyl, isopropyl, and more preferably Is methyl or ethyl, especially methyl. n is an integer of 0-4, preferably an integer of 1-3.
エーテル系溶媒としては、（モノー、ジー、トリー、テトラー）エチレングリコールジメチル エーテル、（モノー、ジー、トリー、テトラー)エチレングリコールジェチルエーテル、（モノ 一、ジー、トリー、テトラー）エチレングリコールジ n—プロピルエーテル、（モノー、ジー、トリ 一、テトラー)エチレングリコールジイソプロピルエーテル、（モノー、ジー、トリー、テトラ—） エチレングリコールジ n—ブチルエーテル、（モノー、ジー、トリー、テトラー）エチレングリコ ールジイソブチルエーテル、（モノー、ジー、トリー、テトラー）エチレングリコールジ sec— ブチルエーテル、（モノー、ジー、トリー、テトラー）エチレングリコールジ tert—ブチルェ 一テルなどのエチレングリコールエーテル系溶媒、（モノー、ジー、トリー、テトラー)プロ ピレングリコールジメチルエーテル、（モノー、ジー、トリー、テトラー)プロピレングリコー ルジェチルエーテル、（モノー、ジー、トリー、テトラー）プロピレングリコールジ n—プロピ ルエーテル、（モノー、ジー、トリー、テトラー）プロピレングリコールジイソプロピルエーテ ル、（モノー、ジー、トリー、テトラー）プロピレングリコールジ n—ブチルエーテル、（モノー、 ジー、トリー、テトラー)プロピレングリコールジイソブチルエーテル、（モノー、ジー、トリー、 テトラー)プロピレングリコールジ sec—ブチルエーテル、（モノー、ジー、トリー、テトラー） プロピレングリコールジ tert—ブチルエーテルなどのプロピレングリコールエーテル系 溶媒、或いは、エチレングリコール Zプロピレングリコール共重合体のジ低級アルキ ルエーテルが挙げられる。 [0011] フッ素化エーテル系溶媒は、上記エーテル系溶媒において、 1個以上の水素原子 力 Sフッ素原子で置換された溶媒を意味し、フッ素原子はアルキレングリコール部分と アルキルエーテル部分の 、ずれにぉ 、て導入されて 、てもよ 、。好まし 、フッ素化 エーテル系溶媒は、一般式（If)または（2f)： Examples of ether solvents include (mono-, di-, tri-, tetra-) ethylene glycol dimethyl ether, (mono-, di-, tri-, tetra-) ethylene glycol getyl ether, (mono-, di, tri, tetra-) ethylene glycol di-n- Propyl ether, (mono, di, tri, tetra) ethylene glycol diisopropyl ether, (mono, di, tri, tetra) ethylene glycol di-n-butyl ether, (mono, di, tri, tetra) ethylene glycol diisobutyl ether , (Mono, di, tri, tetra) ethylene glycol di sec-butyl ether, (mono, di, tri, tetra) ethylene glycol ditert-butyl ether, etc., ethylene glycol ether solvents, (mono, di, etc.) , Tri, tetra) propylene glycol dimethyl ether, (mono, g, tri, tetra) propylene glycol dimethyl ether, (mono, g, tri, tetra) propylene glycol di-n-propyl ether, (mono, g, tri, tetra) ) Propylene glycol diisopropyl ether, (mono-, g-, tri-, tetra-) propylene glycol di-n-butyl ether, (mono-, g-, tri-, tetra-) propylene glycol diisobutyl ether, (mono-, g-, tri, tetra-) propylene glycol di- sec -Butyl ether, (mono-, g-, tri-, tetra-) propylene glycol ether solvents such as propylene glycol di-tert-butyl ether, or ethylene glycol Z propylene Di-lower alkyl ethers of glycol copolymers. [0011] The fluorinated ether-based solvent means a solvent obtained by substituting one or more hydrogen atoms and S fluorine atoms in the above-mentioned ether-based solvents, and the fluorine atom is a difference between the alkylene glycol portion and the alkyl ether portion. , Have been introduced, may be. Preferably, the fluorinated ether solvent is represented by the general formula (If) or (2f):
Rf - 0- (C H F -0) — Rf (If)  Rf-0- (C H F -0) — Rf (If)
m 2 mi m2 nl 1  m 2 mi m2 nl 1
または  Or
Rf -0-(C H F -O) -Rf (2f)  Rf -0- (C H F -O) -Rf (2f)
m 3 m3 m4 nl 1  m 3 m3 m4 nl 1
(式中、 Rf 、 Rfは同一又は異なって C  (Wherein, Rf and Rf are the same or different
m l 1一 Cの直鎖又は分枝を有するフッ素原子で m l 1 C straight or branched fluorine atom
4  Four
置換されていてもよい低級アルキル基を示す、 nlは 0— 4の整数を示す。 ml +m2 =4、 m3 +m4 = 6, ml、 m2、 m3および m4は各々 0又は正の整数を示す。但し、一 般式（If)において、 m2 = 0のとき、 Rf と Rfの少なくとも一方はフッ素原子を含み、  It represents a lower alkyl group which may be substituted, and nl represents an integer of 0-4. ml + m2 = 4, m3 + m4 = 6, ml, m2, m3 and m4 each represent 0 or a positive integer. However, in the general formula (If), when m2 = 0, at least one of Rf and Rf contains a fluorine atom,
m 1  m 1
一般式（2f)において、 m4 = 0のとき、 Rf と Rfの少なくとも一方はフッ素原子を含む  In the general formula (2f), when m4 = 0, at least one of Rf and Rf contains a fluorine atom
m 1  m 1
o )  o)
で表されるフッ素化エーテル系溶媒が挙げられる。 Rf (pは 1  And a fluorinated ether solvent represented by the formula: Rf (p is 1
m、 Rfとしては、 C H F m and Rf are C H F
l p q r 一 4の整数、 q+r = 2p+ l, qおよび rは 0又は正の整数を示す)で表される直鎖又は 分枝を有するフッ素原子で置換されて ヽてもよヽ低級アルキル基を示し、好ましくは トリフルォロメチル、ペンタフルォロェチルなどのパーフルォロアルキル基を示す。 nlは、 0— 4の整数、好ましくは 0— 3の整数である。  lpqr is an integer of 4, q + r = 2p + l, q and r represent 0 or a positive integer) or a lower alkyl group which may be substituted with a linear or branched fluorine atom represented by And preferably a perfluoroalkyl group such as trifluoromethyl and pentafluoroethyl. nl is an integer of 0-4, preferably an integer of 0-3.
n2は、 0— 4の整数、好ましくは 0— 3の整数である。  n2 is an integer of 0-4, preferably an integer of 0-3.
[0012] 好まし 、フッ素化エーテル系溶媒は、毒性が低 ヽ C F OCH (商品名 "HE-7100" [0012] Preferably, the fluorinated ether solvent has a low toxicity 毒性 C F OCH (trade name "HE-7100")
4 9 3  4 9 3
3M製)や、 CF CH OCF CHF (商品名" HFE- 347pc- fダイキン工業製)等が挙げら  3M) and CF CH OCF CHF (trade name “HFE-347pc-f made by Daikin Industries, Ltd.).
3 2 2 2  3 2 2 2
れる。  It is.
[0013] 特に、高選択エッチング液の構成成分であるエーテル系溶媒として、エチレンダリ コールジメチルエーテル (モノグライム）を用いるのが最も好ましい。また、トリエチレン グリコールジメチルエーテル（トリグライム）等の高分子のエーテル系溶媒は、引火点 が高 、（100°C以上)ため、安全性の観点から好ま 、溶媒である。  [0013] Especially, it is most preferable to use ethylene daryl glycol dimethyl ether (monoglyme) as an ether solvent which is a component of the highly selective etching solution. Further, a high molecular ether solvent such as triethylene glycol dimethyl ether (triglyme) has a high flash point (100 ° C. or higher), and is therefore a preferred solvent from the viewpoint of safety.
[0014] これまでに、有機溶媒とフッ化水素酸との混合液を用いた選択的に SiN膜をエッチ ングする方法が報告されている (特許文献 3)。この有機溶媒は、水酸基がついてい る溶媒が特徴である。一方、本発明で用いる原料の有機溶媒は、酸素原子が全てェ 一テル化され、アルコール性又はフエノール性水酸基が無 、エーテル系溶媒 Zフッ 素化エーテル系溶媒であることを特徴して 、る点で異なる。本願明細書の比較例で 示されるように、水酸基の存在は、 SiN膜の選択性を低下させる欠点がある。 [0014] A method of selectively etching a SiN film using a mixed solution of an organic solvent and hydrofluoric acid has been reported (Patent Document 3). This organic solvent has a hydroxyl group. Solvent. On the other hand, the raw material organic solvent used in the present invention is characterized in that all the oxygen atoms are esterified, there is no alcoholic or phenolic hydroxyl group, and the ether solvent is a fluorinated ether solvent. Different in that. As shown in the comparative examples of the present specification, the presence of a hydroxyl group has a drawback that the selectivity of the SiN film is reduced.
[0015] 上記のフッ素化エーテル系溶媒におけるフッ素化されて 、てもよ 、アルキル基 (Rf mThe fluorinated ether-based solvent may be fluorinated to form an alkyl group (Rf m
、 Rf )は、パーフルォロアルキル基でも良い。パーフルォロアルキル基とエーテル結, Rf) may be a perfluoroalkyl group. Perfluoroalkyl group and ether bond
1 1
合を含む有機溶媒は、アルキレングリコール部分のフッ素化の有無にかかわらず引 火性がな!ヽことより、安全性の観点から好まし 、。  The organic solvent containing the compound is not flammable irrespective of whether the alkylene glycol moiety is fluorinated or not, and is therefore preferred from the viewpoint of safety.
エッチング液は、上記に挙げるエーテル系溶媒類が混合された溶媒と、フッ化水素（ The etching solution is a solvent in which the ether solvents mentioned above are mixed, and hydrogen fluoride (
HF)、もしくは希フッ酸との混合液でもよい。フッ素化エーテル系溶媒を、組成に水を 含むフッ化水素酸と混合する場合、水との相溶性の観点から他のエーテル系溶媒と 混合して用いるのが好ま 、。 HF) or a mixed solution with dilute hydrofluoric acid. When the fluorinated ether-based solvent is mixed with hydrofluoric acid containing water in the composition, it is preferable to use the fluorinated ether-based solvent by mixing with another ether-based solvent from the viewpoint of compatibility with water.
[0016] 本発明のエッチング液のエーテル系溶媒及び Z又はフッ素化エーテル系溶媒の 含有量は、通常 99.9一 60.0質量％、好ましくは 99.9一 70.0質量％、より好ましくは 99.9 一 80.0質量0 /0である。 [0016] The content of the ether solvent and Z or fluorinated ether solvent etching solution of the present invention is usually 99.9 one 60.0 wt%, preferably 99.9 one 70.0% by weight, more preferably 99.9 one 80.0 mass 0/0 It is.
[0017] 混合液に含まれるフッ化水素 (HF)の濃度は、 SiN膜を高速エッチングさせる場合 は、高濃度 (例えば 10— 30質量％、より好ましくは 10— 20質量％)が好ましい。また、 高選択性を求める場合は、低濃度 (例えば 0.1— 10質量％、より好ましくは 0.1— 5質 量％)が好ましい。  [0017] The concentration of hydrogen fluoride (HF) contained in the mixed solution is preferably high (for example, 10 to 30% by mass, more preferably 10 to 20% by mass) when the SiN film is etched at a high speed. When high selectivity is required, a low concentration (for example, 0.1 to 10% by mass, more preferably 0.1 to 5% by mass) is preferable.
[0018] 本発明のエッチング液において、水は任意成分であり含まれていてもよいが、全く 含まれていなくてもよい。水の含有量は、通常 10質量％以下、好ましくは 5質量％以 下、より好ましくは 3質量％以下、さらに好ましくは 2質量％、さらにより好ましくは 1質 量％以下、最も好ましくは 0.5質量％以下である。また、水の含有量は、 0質量％であ つてもよい。  In the etching solution of the present invention, water is an optional component and may be contained, but may not be contained at all. The water content is usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, further preferably 2% by mass, still more preferably 1% by mass or less, and most preferably 0.5% by mass or less. % Or less. Further, the content of water may be 0% by mass.
[0019] エッチング液に含まれる水分濃度は、 SiN膜を高選択エッチングする場合は、水分 濃度が少ないことが好ましぐ全く水分がないことがより好ましい。また、水分濃度が増 えると、 SiN膜と SiO膜のエッチング速度が速くなり、水分濃度が増えすぎると SiO膜の エッチング速度が、 SiN膜のエッチング速度より速くなることがある。よって、水分濃度 の調整によって、選択性を調整することが可能である。 [0019] The concentration of water contained in the etching solution is preferably low when the SiN film is highly selectively etched, and more preferably there is no water at all. Also, when the moisture concentration increases, the etching rate of the SiN film and the SiO film increases, and when the moisture concentration increases too much, the etching rate of the SiO film may be faster than the etching rate of the SiN film. Therefore, the moisture concentration It is possible to adjust the selectivity by adjusting.
[0020] エッチング温度を上げるとエッチング速度が増加する。また、 SiN膜のエッチング選 択性も良くなる傾向を示す。よって、エッチング速度、 SiO膜に対する SiN膜の選択ェ ツチング性を高くするためには、エッチング温度を上げることが好ましい。一方、温度 が高すぎると枚葉式の処理が困難になり、 HFのガスが放出される不具合がある。求 めるエッチング速度比、エッチング速度は、温度で調整が可能である。好ましいエツ チング温度は、 100°C以下、好ましくは 20— 80°C、より好ましくは 20〜50°C、さらに 好ましくは 20— 30°Cである。  [0020] Increasing the etching temperature increases the etching rate. In addition, the etching selectivity of the SiN film tends to be improved. Therefore, it is preferable to increase the etching temperature in order to increase the etching rate and the selectivity of the SiN film to the SiO film. On the other hand, if the temperature is too high, single-wafer processing becomes difficult, and HF gas is released. The required etching rate ratio and etching rate can be adjusted by temperature. A preferred etching temperature is 100 ° C or lower, preferably 20 to 80 ° C, more preferably 20 to 50 ° C, and still more preferably 20 to 30 ° C.
[0021] 既存の枚葉式装置では、高温の薬液を安定してウェハー表面に均一に供給するこ とは難しく、 100°Cを超える温度で処理することは実質的に不可能である。よって、 1 00°C以下が好ましい。また、バッチ式、枚葉式とも、温度が室温に近い温度であるほ ど、薬液の昇温時間の短縮ができ、温度制御、管理が容易である。  [0021] With existing single-wafer processing apparatuses, it is difficult to stably supply a high-temperature chemical solution uniformly to the wafer surface, and it is practically impossible to process at a temperature exceeding 100 ° C. Therefore, the temperature is preferably 100 ° C. or lower. In addition, in both the batch type and the single-wafer type, as the temperature is close to room temperature, the time required to raise the temperature of the chemical can be shortened, and the temperature control and management are easy.
[0022] また、エッチング処理時間は、通常 0.05— 5分間、好ましくは 0.1— 2分間である。  [0022] The etching time is generally 0.05-5 minutes, preferably 0.1-2 minutes.
本発明のエッチング処理方法は、処理対象の基板にエッチング液を塗布、噴霧する 方法、エッチング液に基板を浸漬する方法などが挙げられる。  The etching method of the present invention includes a method of applying and spraying an etching solution on a substrate to be processed, a method of dipping the substrate in the etching solution, and the like.
[0023] (膜について）  [0023] (About the membrane)
前記述べられる SiN膜は、プラズマ、熱、光、レーザ、イオンビームの各種 CVD法で 成膜することができる。多く用いられる方法は、プラズマ CVD法、熱 CVD法の低圧 CVD (LP-CVD)法である。  The above-mentioned SiN film can be formed by various CVD methods of plasma, heat, light, laser, and ion beam. Commonly used methods are the low pressure CVD (LP-CVD) method of the plasma CVD method and the thermal CVD method.
[0024] 前記で述べられる SiO膜は、 Si基板、 Si膜を熱酸化させた熱酸化法の SiO膜、ブラ  The SiO film described above includes a Si substrate, a thermally oxidized SiO film obtained by thermally oxidizing a Si film,
2 ズマ、熱、光、レーザ、イオンビームの各種 CVD法で作成する SiO膜、硝酸、硫酸等 で化学反応させたケミカル SiO膜、 Si基板、 Si膜の自然酸化膜、 TE0S膜を包含する。 該 SiO膜には、ボロン（B)、燐（P)、ヒ素 (As)を含む BPSG、 BSG、 AsSGの不純物をドー プした膜は含まれない。  2 Includes SiO films, chemical SiO films chemically reacted with nitric acid, sulfuric acid, etc., Si substrates, natural oxide films of Si films, and TEOS films formed by various CVD methods of plasma, heat, light, laser, and ion beam. The SiO film does not include a film doped with impurities of BPSG, BSG and AsSG containing boron (B), phosphorus (P) and arsenic (As).
[0025] 本発明のエッチング液は、 LP-CVD法の SiN膜と熱酸化法の SiO膜のエッチング選 択比 { (SiN膜のエッチング速度) Z(SiO膜のエッチング速度）}が通常 1. 3以上、好ま しくは 1. 5以上、より好ましくは 2. 0以上、さらに好ましくは 2. 5以上、特に 3以上であ る。 [0026] 本発明のエッチング液は、 SiN膜を SiO膜に対し選択的にエッチングするだけでなくThe etching solution of the present invention usually has an etching selection ratio of {SiN film etching speed Z (SiO film etching speed)} of SiN film of LP-CVD method and SiO film of thermal oxidation method. It is 3 or more, preferably 1.5 or more, more preferably 2.0 or more, still more preferably 2.5 or more, and especially 3 or more. [0026] The etchant of the present invention not only selectively etches the SiN film with respect to the SiO film, but also
、 Si膜或いは Si基板に対しても、選択的にエッチングする。本発明のエッチング液の Si 膜或いは Si基板に対する選択性は、以下の通りである。 The silicon film or the Si substrate is also selectively etched. The selectivity of the etching solution of the present invention to a Si film or a Si substrate is as follows.
[0027] SiN膜と Si膜のエッチング選択比 { (SiN膜のエッチング速度) Z (Si膜のエッチング速 度）}が通常 10以上、好ましくは 100以上、より好ましくは、 Si膜が全くエッチングされ ないことが好ましい。 [0027] The etching selectivity of the SiN film and the Si film {(etching speed of the SiN film) Z (etching speed of the Si film)} is usually 10 or more, preferably 100 or more, and more preferably the Si film is completely etched. Preferably not.
[0028] SiN膜と Si基板のエッチング選択比 { (SiN膜のエッチング速度) / (Si基板のエッチ ングレート）}が通常 10以上、好ましくは 100以上、より好ましくは、 Si基板が全くエツ チングされな 、ことが好まし 、。  [0028] The etching selectivity of the SiN film and the Si substrate {(etching rate of the SiN film) / (etching rate of the Si substrate)} is usually 10 or more, preferably 100 or more, and more preferably the Si substrate is completely etched. What is preferred.
(基板について）  (About board)
本発明において、 SiN膜、 SiO膜は、半導体基板、液晶表示用などのディスプレイ用 ガラス基板、 Si基板、 SiC基板、 GaAs、 InP、 GaP等の化合物半導体基板などが挙げら れる。  In the present invention, examples of the SiN film and the SiO film include a semiconductor substrate, a glass substrate for a display such as a liquid crystal display, a Si substrate, a SiC substrate, and a compound semiconductor substrate such as GaAs, InP, and GaP.
(エッチング液の作成方法）  (How to make etchant)
上記のフッ化水素とエーテル系溶媒及び Z又はフッ素化エーテル系溶媒力 なる 無水のエッチング液を作成する方法は。上記のエーテル系溶媒及び Z又はフッ素化 エーテル系溶媒に、フッ化水素ガスを吸収させる方法と、フッ化水素を 20°C以下に 維持して、液で混合する方法がある。どちらの方法でもよい。含水エッチング液は、フ ッ化水素酸とエーテル系溶媒及び Z又はフッ素化エーテル系溶媒を混合してエッチ ング液としてもよぐ前記で作成したフッ化水素とエーテル系溶媒及び Z又はフッ素 化エーテル系溶媒の混合液に、水を添加しても良い。一般的には、フッ化水素酸と エーテル系溶媒を混ぜて本発明のエッチング液を作成する。  A method for preparing an anhydrous etching solution comprising hydrogen fluoride and an ether solvent and Z or a fluorinated ether solvent is as follows. There are a method of absorbing hydrogen fluoride gas into the above ether solvent and Z or a fluorinated ether solvent, and a method of mixing hydrogen fluoride at a temperature of 20 ° C or less and mixing with a liquid. Either method may be used. The hydrous etching solution is prepared by mixing hydrofluoric acid with an ether-based solvent and Z or a fluorinated ether-based solvent to form an etching solution, and forming the hydrogen fluoride and the ether-based solvent and Z or fluorinated ether as described above. Water may be added to the mixture of the system solvents. Generally, an etching solution of the present invention is prepared by mixing hydrofluoric acid and an ether-based solvent.
[0029] (その他の成分について） [0029] (Other components)
エッチング液は、フッ化水素、もしくはフッ化水素酸と、エーテル系溶媒及び Z又は フッ素化エーテル系溶媒を含む混合液である力 他の界面活性剤、キレート剤、防 食剤を混ぜてもよい。しかし、その他の成分の配合量は 10質量％未満に抑えることが 好ましい。  The etching solution may be a mixture of hydrogen fluoride or hydrofluoric acid and an ether-based solvent and a solvent containing Z or a fluorinated ether-based solvent. Other surfactants, chelating agents, and anticorrosives may be mixed. . However, it is preferable that the compounding amount of other components is suppressed to less than 10% by mass.
実施例 [0030] 以下、本発明を実施例及び比較例を用いてより詳細に説明するが、本発明はこれ ら実施例に限定されるものではない。 Example Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.
実施例 1一 4,比較例 1一 2  Example 11-4, Comparative Example 1-1-2
Si基板上に低圧 (LP-) CVD法で成膜された 2000 Aの SiN膜と、 Si基板上に熱酸ィ匕 法で形成された 2000 Aの SiO膜を用いて、本発明のエッチング方法により、エツチン グ試験を実施した。エッチング前後の膜厚差、エッチング時間よりエッチング速度を 求め、エッチング速度比 (選択性)を導いた。膜厚測定はエリプソメトリー法を用いた。 条件は、各種のエーテル系溶媒、フッ化水素濃度、水濃度を変化させた。  An etching method according to the present invention using a 2000 A SiN film formed on a Si substrate by a low-pressure (LP-) CVD method and a 2000 A SiO film formed on a Si substrate by a thermal oxidation method. , An etching test was conducted. The etching rate was determined from the film thickness difference before and after etching and the etching time, and the etching rate ratio (selectivity) was derived. Ellipsometry was used for measuring the film thickness. The conditions varied various ether solvents, hydrogen fluoride concentration, and water concentration.
[0031] 表 1は、フッ化水素とエーテル系溶媒力もなる本発明のエッチング液と、特許文献 3 に記載された水酸基がついた溶媒とフッ化水素で構成された混合液のエッチング速 度を示している。同一フッ化水素濃度 (maSS%)、同一温度条件での、エッチング特 性を示している。表 1に示すように、水酸基の数が 2→1→0に（エチレングリコール→ エチレングリコールモノブチルエーテル→エチレングリコールジメチルエーテル/比較 例 2→比較例 1→実施例 4)なるに従い、エッチング速度選択性が高くなつていること が示されており、エーテル系溶媒と HFの混合液が、これまで文献で報告されている 有機溶媒とフッ化水素の混合液よりも優位性があることを示している。 [0031] Table 1 shows the etching rates of the etching solution of the present invention, which also has hydrogen fluoride and ether-based solvent power, and the mixed solution composed of a solvent having a hydroxyl group described in Patent Document 3 and hydrogen fluoride. Is shown. The etching characteristics under the same hydrogen fluoride concentration (ma SS %) and the same temperature conditions are shown. As shown in Table 1, as the number of hydroxyl groups becomes 2 → 1 → 0 (ethylene glycol → ethylene glycol monobutyl ether → ethylene glycol dimethyl ether / comparative example 2 → comparative example 1 → example 4), the etching rate selectivity increases. This shows that the mixture is higher, indicating that the mixture of ether-based solvent and HF is superior to the mixture of organic solvent and hydrogen fluoride reported in the literature.
[0032] [表 1]  [Table 1]
Figure imgf000010_0001
試験例 1
Figure imgf000010_0001
Test example 1
表 2に、フッ化水素とエチレングリコールジメチルエーテル力もなる溶媒における水 分濃度に対する、 LP-CVD法の SiN膜と熱酸ィ匕法の SiO膜のエッチング速度と選択性 を示す。水分濃度が増えると、 SiN膜と SiO膜のエッチング速度は速くなる傾向を示し 、 SiN膜の選択エッチング性が下がる傾向を示して 、る。 Table 2 shows that hydrogen fluoride and ethylene glycol dimethyl ether The etching rate and selectivity of the SiN film by the LP-CVD method and the SiO film by the thermal oxidation method are shown with respect to the partial concentration. As the water concentration increases, the etching rates of the SiN film and the SiO film tend to increase, and the selective etching property of the SiN film tends to decrease.
[0034] よって、フッ化水素は、フッ化水素に水が含まれた希フッ酸を用いても良いが、水が 含まれて 、な 、無水フッ化水素のみを用いること力 希フッ酸よりも高選択エッチング が可能である。 [0034] Therefore, as the hydrogen fluoride, dilute hydrofluoric acid in which water is contained in hydrogen fluoride may be used. However, water is contained, and only anhydrous hydrogen fluoride is used. Can also perform highly selective etching.
[0035] また、薬液中の水分濃度を増やしたことによるエッチング速度増加作用は、 SiO膜 の方力 iN膜よりも大きい。よって、水分濃度の調整によって、 SiO膜と SiNを等速エツ チングすることも可能である。  The effect of increasing the etching rate due to the increase in the water concentration in the chemical solution is greater than that of the iN film formed by the SiO film. Therefore, it is possible to etch the SiO film and SiN at a constant speed by adjusting the moisture concentration.
[0036] 表 2は、 60°Cでフッ化水素とエチレングリコールジメチルエーテルの混合液における 水濃度対する LP-CVD法の SiN膜、熱酸ィ匕法の SiOのエッチング速度、速度選択比 依存性を示す。 Table 2 shows the dependence of the water concentration in a mixed solution of hydrogen fluoride and ethylene glycol dimethyl ether at 60 ° C. on the etching rate and the rate selectivity of the SiN film of the LP-CVD method and the SiO of the thermal oxidation method. Show.
[0037] [表 2] [Table 2]
Figure imgf000011_0001
Figure imgf000011_0001
[0038] 試験例 2  [0038] Test example 2
(フッ化水素濃度について）  (About hydrogen fluoride concentration)
混合液に含まれるフッ化水素の濃度を変化させたときのエッチング速度とエツチン グ速度比を表 3に示す。高速エッチングを求める場合は、高濃度が好ましい。また、 高選択性を求める場合は、低濃度が好ましい。  Table 3 shows the ratio of the etching rate to the etching rate when the concentration of hydrogen fluoride contained in the mixture was changed. When high-speed etching is required, a high concentration is preferable. When high selectivity is required, a low concentration is preferable.
[0039] [表 3] フッ化水素とエチレングリコールジメチルェ一テルの混合液における LP-CVD法の SiN膜、 熱酸化法の SiO膜のエッチング速度、 エッチング速度選択比のフッ化水素濃度依存性と温 度依存性 [Table 3] Etch rate of SiN film by LP-CVD method and SiO film by thermal oxidation method in mixed solution of hydrogen fluoride and ethylene glycol dimethyl ether, Dependence of etch rate selectivity on hydrogen fluoride concentration and temperature
Figure imgf000012_0001
Figure imgf000012_0002
(エッチング温度について）
Figure imgf000012_0001
Figure imgf000012_0002
(About etching temperature)
表 3にエッチング温度に対するエッチング速度、エッチング速度選択比の依存性に ついて示す。フッ化水素とエチレングリコールジメチルエーテルの混合液は、温度が 上がると、 SiN膜と SiO膜のエッチング速度が速くなる。エッチング速度比は高くなる傾 向を示す。よって、エッチング温度によって、エッチング速度、選択性を調整すること が可能である。フッ化水素とエチレングリコールジメチルエーテルの混合液にぉ 、て は、温度 80°C、フッ化水素濃度 10mass%においては、 SiN膜のエッチング速度は、 71 A/minが得られ、選択性は、 23が得られている。従来のエッチング液より、 SiN膜を高 い選択比でエッチングすることが可能であることが明らかになった。  Table 3 shows the dependence of the etching rate and the etching rate selectivity on the etching temperature. As the temperature of the mixed solution of hydrogen fluoride and ethylene glycol dimethyl ether increases, the etching rate of the SiN film and the SiO film increases. The etching rate ratio tends to increase. Therefore, the etching rate and the selectivity can be adjusted by the etching temperature. For a mixed solution of hydrogen fluoride and ethylene glycol dimethyl ether, at a temperature of 80 ° C and a hydrogen fluoride concentration of 10 mass%, the etching rate of the SiN film is 71 A / min, and the selectivity is 23. Is obtained. It has become clear that SiN films can be etched with a higher selectivity than conventional etchants.

Claims

請求の範囲 The scope of the claims
[I] フッ化水素、エーテル系溶媒及び Z又はフッ素化エーテル系溶媒、必要に応じてさ らに水を含む、 SiN膜を選択的にエッチングするエッチング液。  [I] An etchant for selectively etching a SiN film, comprising hydrogen fluoride, an ether solvent and a Z or fluorinated ether solvent, and if necessary, water.
[2] 水の含有量がエッチング液の 10質量％以下である請求項 1に記載のエッチング液 [2] The etching solution according to claim 1, wherein the content of water is 10% by mass or less of the etching solution.
[3] 実質的に水を含まな 、請求項 1又は 2に記載のエッチング液。 [3] The etching solution according to claim 1 or 2, substantially containing no water.
[4] エーテル系溶媒及び Z又はフッ素化エーテル系溶媒の含有量は、 99.9一 60質量％[4] The content of the ether solvent and the Z or fluorinated ether solvent is 99.9 to 60% by mass.
、フッ化水素（HF)の含有量が 0.1— 30質量％、水の含有量が 10質量％以下である 請求項 1一 3のいずれかに記載のエッチング液。 14. The etching solution according to claim 13, wherein the content of hydrogen fluoride (HF) is 0.1 to 30% by mass and the content of water is 10% by mass or less.
[5] エーテル系溶媒及び Z又はフッ素化エーテル系溶媒の含有量は、 90— 70質量％、 フッ化水素（HF)の含有量が 10— 30質量％、水の含有量が 10質量％以下である請 求項 1一 3のいずれかに記載のエッチング液。 [5] The content of ether solvent and Z or fluorinated ether solvent is 90-70% by mass, the content of hydrogen fluoride (HF) is 10-30% by mass, and the content of water is 10% by mass or less. 4. The etching solution according to claim 1, wherein the etching solution is:
[6] エーテル系溶媒及び Z又はフッ素化エーテル系溶媒の含有量は、 99.9一 90質量％[6] The content of the ether solvent and the Z or fluorinated ether solvent is 99.9-90% by mass.
、フッ化水素（HF)の含有量が 0.1— 10質量％、水の含有量力 ¾質量％以下である請 求項 1一 3のいずれかに記載のエッチング液。 The etching solution according to claim 13, wherein the content of hydrogen fluoride (HF) is 0.1 to 10% by mass and the content of water is not more than ¾% by mass.
[7] エーテル系溶媒及び Z又はフッ素化エーテル系溶媒力 グリコールジエーテル系溶 媒である請求項 1一 3のいずれかに記載のエッチング液。 [7] The etching solution according to any one of [13] to [13], wherein the etching solution is an ether-based solvent and a Z or fluorinated ether-based solvent glycol diether-based solvent.
[8] グリコールジエーテル系溶媒が、エチレングリコールジメチルエーテル（モノグライム） である請求項 7に記載のエッチング液。 [8] The etching solution according to claim 7, wherein the glycol diether solvent is ethylene glycol dimethyl ether (monoglyme).
[9] グリコールジエーテル系溶媒力 トリエチレングリコールジメチルエーテル（トリグライ ム）である請求項 7に記載のエッチング液。 [9] The etching solution according to claim 7, wherein the solvent is glycol diether-based solvent triethylene glycol dimethyl ether (triglyme).
[10] グリコールジエーテル系溶媒が、ジエチレングリコールジメチルエーテル（ジグライム) である請求項 7に記載のエッチング液。 [10] The etching solution according to claim 7, wherein the glycol diether solvent is diethylene glycol dimethyl ether (diglyme).
[II] グリコールジエーテル系溶媒力 ジエチレングリコールジェチルエーテルである請求 項 7に記載のエッチング液。  [II] The etching solution according to claim 7, which is a glycol diether solvent power diethylene glycol getyl ether.
[12] エーテル系溶媒及び Z又はフッ素化エーテル系溶媒力 パーフルォロエーテル系 溶媒である請求項 1一 3のいずれかに記載のエッチング液。  [12] The etching solution according to any one of [13] to [13], wherein the etching solution is an ether-based solvent and a Z or fluorinated ether-based solvent perfluoroether-based solvent.
[13] エーテル系溶媒及び Z又はフッ素化エーテル系溶媒力 C F OCH及び [13] ether solvents and Z or fluorinated ether solvents C F OCH and
4 9 3 Z又は CF  4 9 3 Z or CF
3 Three
CH OCF CHFである請求項 1一 3のいずれかに記載のエッチング液。 14. The etching solution according to claim 13, which is CH OCF CHF.
[14] SiN膜とともに SiO膜を含む基板を、請求項 1一 13のいずれかに記載のエッチング液 を用いて 100°C以下の温度でエッチングすることを特徴とする、 SiN膜を選択的にエツ チングする方法。 [14] A substrate including a SiON film together with a SiN film is etched at a temperature of 100 ° C or lower using the etching solution according to any one of claims 11 to 13, wherein the SiN film is selectively etched. How to etch.
[15] 前記基板が半導体基板又はガラス基板である請求項 14に記載の方法。  15. The method according to claim 14, wherein the substrate is a semiconductor substrate or a glass substrate.
[16] エッチング温度が 20— 50°Cである請求項 14又は 15に記載の方法。 [16] The method according to claim 14 or 15, wherein the etching temperature is 20 to 50 ° C.
[17] エッチング温度が 20— 30°Cである請求項 16に記載の方法。 [17] The method according to claim 16, wherein the etching temperature is 20-30 ° C.
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