JP5423788B2 - Etching solution and method for producing the same, etching method using the etching solution, and method for producing an etched product - Google Patents

Etching solution and method for producing the same, etching method using the etching solution, and method for producing an etched product Download PDF

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JP5423788B2
JP5423788B2 JP2011507078A JP2011507078A JP5423788B2 JP 5423788 B2 JP5423788 B2 JP 5423788B2 JP 2011507078 A JP2011507078 A JP 2011507078A JP 2011507078 A JP2011507078 A JP 2011507078A JP 5423788 B2 JP5423788 B2 JP 5423788B2
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充司 板野
新吾 中村
健彦 毛塚
友亮 江藤
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/302Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
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    • H01L21/31Treatment 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
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    • H01L21/04Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/302Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
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Description

本発明は、半導体工程、液晶工程等に用いられるシリコン酸化膜のエッチング液、その製造方法、該エッチング液を用いたエッチング方法、及び該エッチング液を用いたエッチング処理物の製造方法に関する。   The present invention relates to an etching solution for a silicon oxide film used in a semiconductor process, a liquid crystal process, and the like, a manufacturing method thereof, an etching method using the etching solution, and a manufacturing method of an etched product using the etching solution.

シリコン酸化膜のウェットエッチング液は、フッ化水素酸とフッ化アンモニウム溶液との混合液であるバッファードフッ酸が用いられている(例えば、特許文献1)。半導体製造工程においては、バッファードフッ酸を入れた薬液槽にウエハを浸漬してエッチングを行うが、通常薬液槽はウエハ浸漬のため開口部を有しているため、薬液成分の蒸発により経時的に薬液組成が変化してしまい、エッチングレートに重大な影響を与えることが知られている。そのため、時間の経過とともに薬液全量を交換せざるを得ず、処理の効率及び資源の有効利用の点で問題があった。   Buffered hydrofluoric acid, which is a mixture of hydrofluoric acid and ammonium fluoride solution, is used as the wet etching solution for the silicon oxide film (for example, Patent Document 1). In the semiconductor manufacturing process, etching is performed by immersing the wafer in a chemical bath containing buffered hydrofluoric acid. Usually, the chemical bath has an opening for immersing the wafer. It is known that the chemical composition changes and the etching rate is seriously affected. For this reason, the total amount of the chemical solution has to be changed over time, and there is a problem in terms of processing efficiency and effective use of resources.

特許文献1の段落番号[0005]には、「薬液組成がHF:0.1%、NHF:40%のバッファードフッ酸(BHF)の場合、熱酸化膜のエッチングレートが25℃で1.6nm/minである。しかしこのような薬液を湿度40%、雰囲気温度25℃の環境下で3日間放置するとエッチングレートが4.2nm/minと約2.6倍に増加する。このような環境で変化する薬液は今後の半導体プロセスにおいて使用は不可能である。」と記載されている。In paragraph [0005] of Patent Document 1, “In the case of buffered hydrofluoric acid (BHF) having a chemical composition of HF: 0.1% and NH 4 F: 40%, the etching rate of the thermal oxide film is 25 ° C. However, if such a chemical solution is left for 3 days in an environment with a humidity of 40% and an ambient temperature of 25 ° C., the etching rate increases to about 2.6 times as 4.2 nm / min. Chemicals that change in different environments cannot be used in future semiconductor processes. "

バッファードフッ酸中のフッ化アンモニウム、アンモニウムイオン及びフッ化水素酸の解離は以下の(1)式から(4)式で表される。   Dissociation of ammonium fluoride, ammonium ions and hydrofluoric acid in buffered hydrofluoric acid is expressed by the following formulas (1) to (4).

Figure 0005423788
Figure 0005423788

特許文献1で述べられているような薬液組成(HF=0.1mass%、NHF=40mass%)のバッファードフッ酸は、例えば湿度40%、温度25℃の環境下に放置すると(2)式によりアンモニアが蒸発し、プロトン(H)が液中に発生する。フッ化水素酸はpKa=3.17の弱酸であるために、Hが発生すると(1)式から生じるフッ化物イオン(F)と反応し(3)式によりフッ化水素(HF)が発生する。生成したHFはさらにFと反応しシリコン酸化膜のエッチング種であるHF が発生する。従って、このような薬液組成のバッファードフッ酸を放置すれば、薬液組成が変化してシリコン酸化膜のエッチングレートが速くなるために薬液は使用不可になる。Buffered hydrofluoric acid having a chemical composition (HF = 0.1 mass%, NH 4 F = 40 mass%) as described in Patent Document 1 is left, for example, in an environment with a humidity of 40% and a temperature of 25 ° C. (2 ), The ammonia evaporates and protons (H + ) are generated in the liquid. Since hydrofluoric acid is a weak acid with pKa = 3.17, when H + is generated, it reacts with fluoride ions (F ) generated from the formula (1), and hydrogen fluoride (HF) is converted by the formula (3). Occur. The generated HF further reacts with F to generate HF 2 which is an etching species of the silicon oxide film. Therefore, if the buffered hydrofluoric acid having such a chemical composition is allowed to stand, the chemical composition is changed and the etching rate of the silicon oxide film is increased, so that the chemical cannot be used.

また、特許文献1の段落番号[0019]には、「NHF濃度が30mass%を超えると薬液の蒸発量は少ないが、薬液の組成割合が変化する。従って元の組成に戻すことが困難である。」と記載されている。Further, in paragraph [0019] of Patent Document 1, “When the NH 4 F concentration exceeds 30 mass%, the amount of evaporation of the chemical solution is small, but the composition ratio of the chemical solution changes. Therefore, it is difficult to return to the original composition. It is described.

また、特許文献1には、バッファードフッ酸、特にHF濃度が0.1mass%以下でNHF濃度が30mass%以下のバッファードフッ酸に関して、薬液組成の経時変化を少なくするために、組成調整用薬液を薬液槽に供給して組成変化した薬液槽中の薬液を所定の薬液組成に維持する技術が記載されている。これは薬液の使用環境を制御することで薬液組成変化をなくことが記載されているにすぎず、薬液そのものの改良により組成変化を少なくするものではない。Patent Document 1 discloses a composition of buffered hydrofluoric acid, particularly for buffered hydrofluoric acid having an HF concentration of 0.1 mass% or less and an NH 4 F concentration of 30 mass% or less in order to reduce the change over time of the chemical composition. A technique is described in which a chemical solution in a chemical solution tank whose composition has been changed by supplying an adjustment chemical solution to the chemical solution tank is maintained at a predetermined chemical solution composition. This only describes that there is no change in the chemical composition by controlling the use environment of the chemical, and the change in the composition is not reduced by improving the chemical itself.

また、半導体製造工程においては、通常バッファードフッ酸を入れた薬液槽にウエハを浸漬してエッチングを行うが、通常薬液槽はウエハ浸漬のため開口部を有しているため、前段の超純水リンス槽から水が薬液槽に持ち込まれ薬液成分の希釈により経時的に薬液組成が変化してしまい、エッチングレートに重大な影響を与えることも知られている。そのため、時間の経過とともに薬液全量を交換せざるを得ず、処理の効率及び資源の有効利用の点で問題があった。   In the semiconductor manufacturing process, etching is usually performed by immersing the wafer in a chemical bath containing buffered hydrofluoric acid. Usually, the chemical bath has an opening for immersing the wafer. It is also known that water is brought from the water rinsing tank into the chemical tank and the chemical composition changes over time due to dilution of the chemical components, which significantly affects the etching rate. For this reason, the total amount of the chemical solution has to be changed over time, and there is a problem in terms of processing efficiency and effective use of resources.

特開平9−22891号公報JP-A-9-22891

本発明は、薬液の蒸発等に伴う組成変化が少なく、薬液の交換頻度が少なくてすみ、かつ、経時的にも均一にシリコン酸化膜をエッチング可能なエッチング液を提供することを目的とする。   It is an object of the present invention to provide an etching solution that can cause a silicon oxide film to be etched uniformly over time with little change in composition associated with evaporation of the chemical solution and the like, and less frequent chemical solution replacement.

本発明者らは、上記の課題を解決するため鋭意研究を行った結果、下記の知見を得た。   As a result of intensive studies to solve the above problems, the present inventors have obtained the following knowledge.

フッ化水素酸(pKa=3.17)より高いpKaを有する酸と、アンモニア(pKa=9.24)より高い塩基の塩(A・B)をバッファードフッ酸に添加すると、HF濃度と酸化膜エッチングレートとの関係式(y=aX+b;yは酸化膜エッチングレート(Å/分)、Xはフッ化水素濃度(mass%))で傾きaの小さいエッチング液が得られる。傾きaが小さいエッチング液であれば、薬液が蒸発してHF濃度が高くなってもより酸化膜エッチングレートの増加は少なくなる。また、水で希釈されてHF濃度が低くなっても酸化膜エッチングレートの減少は少なくなる。   When an acid having a pKa higher than hydrofluoric acid (pKa = 3.17) and a salt of a base (A · B) higher than ammonia (pKa = 9.24) are added to buffered hydrofluoric acid, the concentration of HF and oxidation are increased. An etching solution having a small inclination a with a relational expression with the film etching rate (y = aX + b; y is an oxide film etching rate (Å / min) and X is a hydrogen fluoride concentration (mass%)) is obtained. If the etching solution has a small slope a, the increase in the oxide film etching rate is reduced even if the chemical solution evaporates and the HF concentration increases. Further, even if diluted with water and the HF concentration is lowered, the decrease in the oxide film etching rate is reduced.

従って、バッファードフッ酸を放置していても、薬液の蒸発等に伴う組成変化が小さいためシリコン酸化膜のエッチングレートが速くならず、その結果、薬液交換頻度が少ない寿命の長いエッチング液を提供することができる。かかる知見に基づき更に研究を重ねた結果、本発明を完成するに至った。   Therefore, even if the buffered hydrofluoric acid is left unattended, the composition change accompanying the evaporation of the chemical solution is small, so the etching rate of the silicon oxide film does not increase, and as a result, a long-life etching solution with a low chemical replacement frequency is provided. can do. As a result of further research based on this knowledge, the present invention has been completed.

即ち、本発明は下記のエッチング液を提供する。   That is, the present invention provides the following etching solution.

項1.(A)フッ化水素酸、
(B)フッ化アンモニウム、
(C)フッ化水素酸(pKa=3.17)より大きいpKaを有する酸(C1)とアンモニア(pKa=9.24)より大きいpKaを有する塩基(C2)とからなる塩、及び
(D)水
を含むエッチング液。
Item 1. (A) hydrofluoric acid,
(B) ammonium fluoride,
(C) a salt comprising an acid (C1) having a pKa greater than hydrofluoric acid (pKa = 3.17) and a base (C2) having a pKa greater than ammonia (pKa = 9.24), and (D) Etching solution containing water.

項2.酸(C1)のpKaが、3.17より大きく、7未満である項1に記載のエッチング液。   Item 2. Item 2. The etching solution according to Item 1, wherein the pKa of the acid (C1) is greater than 3.17 and less than 7.

項3.酸(C1)が、蟻酸(pKa=3.75)、酢酸(pKa=4.56)、マロン酸(2段目のpKa=5.28)、クエン酸(3段目のpKa=5.69)、マレイン酸(2段目のpKa=5.83)、2−(N−モルホリノ)エタンスルホン酸(pKa=6.1)及び炭酸(1段目のpKa=6.35)よりなる群から選ばれる少なくとも1種である項1又は2に記載のエッチング液。   Item 3. Acid (C1) is formic acid (pKa = 3.75), acetic acid (pKa = 4.56), malonic acid (second stage pKa = 5.28), citric acid (third stage pKa = 5.69). ), Maleic acid (second stage pKa = 5.83), 2- (N-morpholino) ethanesulfonic acid (pKa = 6.1) and carbonic acid (first stage pKa = 6.35). Item 3. The etching solution according to Item 1 or 2, which is at least one selected.

項4.酸(C1)が、酢酸である項1〜3のいずれかに記載のエッチング液。   Item 4. Item 4. The etching solution according to any one of Items 1 to 3, wherein the acid (C1) is acetic acid.

項5.塩基(C2)が、第一アミン(C2a)、第二アミン(C2b)、第三アミン(C2c)及び第四級アンモニウム(C2d)よりなる群から選ばれる少なくとも1種である項1〜4のいずれかに記載のエッチング液。   Item 5. Item 1. The base (C2) is at least one selected from the group consisting of a primary amine (C2a), a secondary amine (C2b), a tertiary amine (C2c), and a quaternary ammonium (C2d). The etching liquid in any one.

項6.第一アミン(C2a)が、メチルアミン(pKa=10.6)、エチルアミン(pKa=10.6)、プロピルアミン(pKa=10.6)、ブチルアミン(pKa=10.6)、ペンチルアミン(pKa=10.0)、エタノールアミン(pKa=9.3)、プロパノールアミン(pKa=9.3)、ブタノールアミン(pKa=9.3)、メトキシエチルアミン(pKa=10.0)及びメトキシプロピルアミン(pKa=10.0)よりなる群から選ばれる少なくとも1種である項5に記載のエッチング液。   Item 6. Primary amine (C2a) is methylamine (pKa = 10.6), ethylamine (pKa = 10.6), propylamine (pKa = 10.6), butylamine (pKa = 10.6), pentylamine (pKa) = 10.0), ethanolamine (pKa = 9.3), propanolamine (pKa = 9.3), butanolamine (pKa = 9.3), methoxyethylamine (pKa = 10.0) and methoxypropylamine ( Item 6. The etching solution according to Item 5, which is at least one selected from the group consisting of pKa = 10.0).

項7.第二アミン(C2b)が、ジメチルアミン(pKa=10.8)、ジエチルアミン(pKa=10.9)及びジプロピルアミン(pKa=10.8)よりなる群から選ばれる少なくとも1種である項5又は6に記載のエッチング液。   Item 7. Item 5 is wherein the secondary amine (C2b) is at least one selected from the group consisting of dimethylamine (pKa = 10.8), diethylamine (pKa = 10.9) and dipropylamine (pKa = 10.8). Or the etching liquid of 6.

項8.第三アミン(C2c)が、トリメチルアミン(pKa=9.80)及びトリエチルアミン(pKa=10.72)よりなる群から選ばれる少なくとも1種である項5〜7のいずれかに記載のエッチング液。   Item 8. Item 8. The etching solution according to any one of Items 5 to 7, wherein the tertiary amine (C2c) is at least one selected from the group consisting of trimethylamine (pKa = 9.80) and triethylamine (pKa = 10.72).

項9.第四級アンモニウム(C2d)が、テトラメチルアンモニウムハイドロオキサイド(pKa=14.0)、テトラエチルアンモニウムハイドロオキサイド(pKa=14.0)及びコリン(pKa=13.2)よりなる群から選ばれる少なくとも1種である項5〜8のいずれかに記載のエッチング液。   Item 9. Quaternary ammonium (C2d) is at least one selected from the group consisting of tetramethylammonium hydroxide (pKa = 14.0), tetraethylammonium hydroxide (pKa = 14.0) and choline (pKa = 13.2). Item 9. The etching solution according to any one of Items 5 to 8, which is a seed.

項10.塩基(C2)が、テトラメチルアンモニウムハイドロオキサイドである項1〜5のいずれかに記載のエッチング液。   Item 10. Item 6. The etching solution according to any one of Items 1 to 5, wherein the base (C2) is tetramethylammonium hydroxide.

項11.さらに、界面活性剤(E)を含む項1〜10のいずれかに記載のエッチング液。   Item 11. Furthermore, the etching liquid in any one of claim | item 1 -10 containing surfactant (E).

項12.(A)フッ化水素酸、
(B)フッ化アンモニウム、
(C)フッ化水素酸(pKa=3.17)より大きいpKaを有する酸(C1)とアンモニア(pKa=9.24)より大きいpKaを有する塩基(C2)とからなる塩、及び
(D)水
を混合することを特徴とする項1〜11のいずれかに記載のエッチング液の製造方法。
Item 12. (A) hydrofluoric acid,
(B) ammonium fluoride,
(C) a salt comprising an acid (C1) having a pKa greater than hydrofluoric acid (pKa = 3.17) and a base (C2) having a pKa greater than ammonia (pKa = 9.24), and (D) Item 12. The method for producing an etching solution according to any one of Items 1 to 11, wherein water is mixed.

項13.項1〜11のいずれかに記載のエッチング液を用いて被エッチング物をエッチング処理することを特徴とするエッチング方法。   Item 13. Item 12. An etching method comprising etching an object to be etched using the etching solution according to any one of Items 1 to 11.

項14.項1〜11のいずれかに記載のエッチング液を用いて被エッチング物をエッチング処理することを特徴とするエッチング処理物の製造方法。   Item 14. Item 12. A method for producing an etched product, comprising etching an object to be etched using the etching solution according to any one of Items 1 to 11.

本発明のエッチング液は、薬液の蒸発、希釈等に伴う組成変化が少なく、薬液の交換頻度が少なくてすみ、かつ、経時的にも均一にシリコン酸化膜をエッチング可能である。   The etching solution of the present invention has little composition change accompanying the evaporation, dilution, etc. of the chemical solution, requires less frequent replacement of the chemical solution, and can uniformly etch the silicon oxide film over time.

実施例8〜11及び比較例3〜4ついて、HF濃度とエッチングレートとの関係を示すグラフである。It is a graph which shows the relationship between HF density | concentration and an etching rate about Examples 8-11 and Comparative Examples 3-4.

本発明のエッチング液は、(A)フッ化水素酸;(B)フッ化アンモニウム;(C)フッ化水素酸(pKa=3.17)より大きいpKaを有する酸(C1)とアンモニア(pKa=9.24)より大きいpKaを有する塩基(C2)とからなる塩;及び(D)水を含むバッファードフッ酸である。   The etching solution of the present invention comprises (A) hydrofluoric acid; (B) ammonium fluoride; (C) acid (C1) having a pKa greater than hydrofluoric acid (pKa = 3.17) and ammonia (pKa = 9.24) a salt consisting of a base (C2) having a larger pKa; and (D) buffered hydrofluoric acid containing water.

フッ化水素酸(A)の添加量は、特に限定されるわけではないが、エッチングが好適に実施できるフッ化水素(HF)濃度となるように添加することが好ましい。例えば、エッチング液の総重量に対してHFの濃度が10mass%以下、好ましくは0.001〜9mass%、より好ましくは0.005〜8mass%、特に好ましくは0.005〜7mass%となるように配合すればよい。   The amount of hydrofluoric acid (A) to be added is not particularly limited, but it is preferable to add hydrofluoric acid (A) so as to have a hydrogen fluoride (HF) concentration at which etching can be suitably performed. For example, the concentration of HF is 10 mass% or less, preferably 0.001 to 9 mass%, more preferably 0.005 to 8 mass%, and particularly preferably 0.005 to 7 mass% with respect to the total weight of the etching solution. What is necessary is just to mix | blend.

フッ化水素の濃度がこの範囲であればエッチング液として好適であるが、薬液中のHF濃度が低いほど、長時間放置後のエッチングレートの変化(増加)が大きくなる。本発明では、かかる低いHF濃度のエッチング液でも、後述の所定の塩の添加により、エッチングレートの変化を抑えることができるものである。   If the concentration of hydrogen fluoride is in this range, it is suitable as an etching solution. However, the lower the HF concentration in the chemical solution, the greater the change (increase) in the etching rate after standing for a long time. In the present invention, even with an etching solution having such a low HF concentration, the change in the etching rate can be suppressed by adding a predetermined salt described later.

フッ化アンモニウム(NHF)(B)の含有量は、1〜45mass%、好ましくは10〜40mass%の任意の濃度でよい。The content of ammonium fluoride (NH 4 F) (B) may be an arbitrary concentration of 1 to 45 mass%, preferably 10 to 40 mass%.

エッチング液に添加される塩(C)は、フッ化水素酸(pKa=3.17)より大きいpKaを有する酸(C1)と、アンモニア(pKa=9.24)より大きいpKaを有する塩基(C2)とからなる塩が選択される。かかる塩をバッファードフッ酸に添加すると、HF濃度と酸化膜エッチングレートとの関係式(y=aX+b;yは酸化膜エッチングレート(Å/分)、Xはフッ化水素濃度(mass%))で傾きaの小さいエッチング液が得られる。傾きaの小さいエッチング液であれば、薬液が蒸発してHF濃度が高くなってもより酸化膜エッチングレートの増加は少なくなる。また、水で希釈されてHF濃度が低くなっても酸化膜エッチングレートの減少は少なくなる。これにより、経時的にエッチングレートの変化の少ないエッチング液となる。   The salt (C) added to the etching solution includes an acid (C1) having a pKa greater than hydrofluoric acid (pKa = 3.17) and a base (C2) having a pKa greater than ammonia (pKa = 9.24). ) Is selected. When such a salt is added to buffered hydrofluoric acid, the relational expression between HF concentration and oxide film etching rate (y = aX + b; y is oxide film etching rate (エ ッ チ ン グ / min), X is hydrogen fluoride concentration (mass%)) Thus, an etching solution having a small inclination a can be obtained. If the etching solution has a small inclination a, the increase in the oxide film etching rate is reduced even if the chemical solution evaporates and the HF concentration increases. Further, even if diluted with water and the HF concentration is lowered, the decrease in the oxide film etching rate is reduced. As a result, an etching solution with little change in etching rate over time is obtained.

塩(C)に用いられる酸(C1)としては、そのpKaが3.17(フッ化水素酸のpKa)より大きいことが重要である。pKaがフッ化水素酸(pKa=3.7)より大きい酸(C1)を使用することで、上記(3)式によるHFの発生を抑えることができる。この結果として、長時間放置しても、薬液組成が変化するのを抑制できる。   As the acid (C1) used for the salt (C), it is important that its pKa is larger than 3.17 (pKa of hydrofluoric acid). By using an acid (C1) whose pKa is larger than hydrofluoric acid (pKa = 3.7), generation of HF according to the above formula (3) can be suppressed. As a result, the chemical composition can be prevented from changing even when left for a long time.

この酸(C1)の具体例としては、例えば、蟻酸(pKa=3.75)、酢酸(pKa=4.56)、マロン酸(2段目のpKa=5.28)、クエン酸(3段目のpKa=5.69)、マレイン酸(2段目のpKa=5.83)、2−(N−モルホリノ)エタンスルホン酸(pKa=6.1)、炭酸(1段目のpKa=6.35)等が挙げられる。これらの酸(C1)は、1種単独で用いてもよいし、2種以上を組み合わせて用いてもよい。酸(C1)としては、好ましくはpKaが3.17より大きく7未満、より好ましくはpKaが4以上7未満、さらに好ましくはpKaが4.5〜6.5のものである。pKaが最も好ましい範囲内にある酸(C1)の具体例は、酢酸(pKa=4.56)、マロン酸(2段目のpKa=5.28)、クエン酸(3段目のpKa=5.69)、マレイン酸(2段目のpKa=5.83)、2−(N−モルホリノ)エタンスルホン酸(pKa=6.1)、炭酸(1段目のpKa=6.35)等であり、なかでも、酢酸(pKa=4.56)が好ましい。   Specific examples of the acid (C1) include, for example, formic acid (pKa = 3.75), acetic acid (pKa = 4.56), malonic acid (second-stage pKa = 5.28), citric acid (third-stage PKa = 5.69), maleic acid (second stage pKa = 5.83), 2- (N-morpholino) ethanesulfonic acid (pKa = 6.1), carbonic acid (first stage pKa = 6) .35) and the like. These acids (C1) may be used individually by 1 type, and may be used in combination of 2 or more type. The acid (C1) preferably has a pKa greater than 3.17 and less than 7, more preferably a pKa of 4 or more and less than 7, and still more preferably a pKa of 4.5 to 6.5. Specific examples of the acid (C1) having a pKa in the most preferable range include acetic acid (pKa = 4.56), malonic acid (second stage pKa = 5.28), citric acid (third stage pKa = 5). .69), maleic acid (second stage pKa = 5.83), 2- (N-morpholino) ethanesulfonic acid (pKa = 6.1), carbonic acid (first stage pKa = 6.35), etc. Among them, acetic acid (pKa = 4.56) is preferable.

塩(C)に用いられる塩基(C2)としては、そのpKaが9.24(アンモニアのpKa)より大きいことが重要である。pKaがアンモニア(pKa=9.24)より大きい塩基(C2)を使用することで、上記(2)式によるプロトンの発生を抑えることができる。この結果として、長時間放置しても、薬液組成が変化するのを抑制できる。   As the base (C2) used in the salt (C), it is important that its pKa is larger than 9.24 (pKa of ammonia). By using a base (C2) whose pKa is larger than ammonia (pKa = 9.24), generation of protons according to the above formula (2) can be suppressed. As a result, the chemical composition can be prevented from changing even when left for a long time.

この塩基(C2)としては、有機アミン類(例えば第一アミン(C2a)、第二アミン(C2b)、第三アミン(C2c)、第四級アンモニウム(C2d)等)等が使用できる。   As the base (C2), organic amines (for example, primary amine (C2a), secondary amine (C2b), tertiary amine (C2c), quaternary ammonium (C2d), etc.) can be used.

第一アミン(C2a)としては、例えば、メチルアミン(pKa=10.6)、エチルアミン(pKa=10.6)、プロピルアミン(pKa=10.6)、ブチルアミン(pKa=10.6)、ペンチルアミン(pKa=10.0)、エタノールアミン(pKa=9.3)、プロパノールアミン(pKa=9.3)、ブタノールアミン(pKa=9.3)、メトキシエチルアミン(pKa=10.0)、メトキシプロピルアミン(pKa=10.0)等が挙げられ、第二アミン(C2b)としては、例えば、ジメチルアミン(pKa=10.8)、ジエチルアミン(pKa=10.9)、ジプロピルアミン(pKa=10.8)等が挙げられ、第三アミン(C2c)としては、例えば、トリメチルアミン(pKa=9.80)、トリエチルアミン(pKa=10.72)等が挙げられ、第四級アンモニウムとしては、例えば、テトラメチルアンモニウムハイドロオキサイド(pKa=14.0)、テトラエチルアンモニウムハイドロオキサイド(pKa=14.0)、コリン(pKa=13.2)等が挙げられる。これらの塩基(C2)は、1種単独で用いてもよいし、2種以上を組み合わせて用いてもよい。   Examples of the primary amine (C2a) include methylamine (pKa = 10.6), ethylamine (pKa = 10.6), propylamine (pKa = 10.6), butylamine (pKa = 10.6), and pentyl. Amine (pKa = 10.0), ethanolamine (pKa = 9.3), propanolamine (pKa = 9.3), butanolamine (pKa = 9.3), methoxyethylamine (pKa = 10.0), methoxy Examples of the secondary amine (C2b) include dimethylamine (pKa = 10.8), diethylamine (pKa = 10.9), dipropylamine (pKa = 10.8) and the like, and as the tertiary amine (C2c), for example, trimethylamine (pKa = 9.80), triethyl And quaternary ammonium include, for example, tetramethylammonium hydroxide (pKa = 14.0), tetraethylammonium hydroxide (pKa = 14.0), choline (pKa) = 13.2) and the like. These bases (C2) may be used individually by 1 type, and may be used in combination of 2 or more type.

塩基(C2)としては、pKaが9.24より大きいものであり、好ましくはpKaが10以上、より好ましくはpKaが10.5以上のものである。塩基(C2)のpKaの上限値は、特に制限されるわけではないが、通常14程度である。   The base (C2) has a pKa greater than 9.24, preferably a pKa of 10 or more, more preferably a pKa of 10.5 or more. The upper limit of the pKa of the base (C2) is not particularly limited, but is usually about 14.

pKaが最も好ましい範囲内にある塩基(C2)の具体例は、メチルアミン(pKa=10.6)、エチルアミン(pKa=10.6)、プロピルアミン(pKa=10.6)、ブチルアミン(pKa=10.6)、ジメチルアミン(pKa=10.8)、ジエチルアミン(pKa=10.9)、ジプロピルアミン(pKa=10.8)、トリエチルアミン(pKa=10.72)、テトラメチルアンモニウムハイドロオキサイド(pKa=14.0)、テトラエチルアンモニウムハイドロオキサイド(pKa=14.0)、コリン(pKa=13.2)等であり、なかでも、テトラメチルアンモニウムハイドロオキサイドが好ましい。   Specific examples of the base (C2) in which pKa is in the most preferable range are methylamine (pKa = 10.6), ethylamine (pKa = 10.6), propylamine (pKa = 10.6), butylamine (pKa = 10.6), dimethylamine (pKa = 10.8), diethylamine (pKa = 10.9), dipropylamine (pKa = 10.8), triethylamine (pKa = 10.72), tetramethylammonium hydroxide ( pKa = 14.0), tetraethylammonium hydroxide (pKa = 14.0), choline (pKa = 13.2), etc. Among them, tetramethylammonium hydroxide is preferable.

上述した酸(C1)と塩基(C2)とからなる好ましい塩(C)の具体例としては、例えば、酢酸とメチルアミンとからなる塩、酢酸とエチルアミンとからなる塩、酢酸とジメチルアミンとからなる塩、酢酸とトリメチルアミンとからなる塩、酢酸とテトラメチルアンモニウムハイドロオキサイドとからなる塩、酢酸とコリンとからなる塩、蟻酸とテトラメチルアンモニウムハイドロオキサイドとからなる塩等が挙げられる。好ましくは、酢酸とテトラメチルアンモニウムハイドロオキサイドとからなる塩である。   Specific examples of the preferred salt (C) composed of the acid (C1) and the base (C2) described above include, for example, a salt composed of acetic acid and methylamine, a salt composed of acetic acid and ethylamine, and acetic acid and dimethylamine. A salt consisting of acetic acid and trimethylamine, a salt consisting of acetic acid and tetramethylammonium hydroxide, a salt consisting of acetic acid and choline, a salt consisting of formic acid and tetramethylammonium hydroxide, and the like. A salt composed of acetic acid and tetramethylammonium hydroxide is preferable.

塩(C)の添加量は、例えば、エッチング液の全重量に対して0.01〜5mol/kg、好ましくは0.05〜4mol/kg、より好ましくは0.1〜3mol/kgである。かかる範囲とすることにより、長時間放置後でもエッチングレートの変化の少ないエッチング液が得られる。   The amount of salt (C) added is, for example, 0.01 to 5 mol / kg, preferably 0.05 to 4 mol / kg, more preferably 0.1 to 3 mol / kg, based on the total weight of the etching solution. By setting it within such a range, an etching solution with little change in etching rate can be obtained even after being left for a long time.

本発明の好適なエッチング液としては、エッチング液の全重量を基準として、フッ化水素(A)0.05〜7mass%、フッ化アンモニウム(B)1〜45mass%、pKaが4.5〜6.5の酸(C1)とpKaが10.5以上の塩基(C2)とからなる塩(C)0.1〜3mol/kg及び残り水を含むシリコン酸化膜のエッチング液が挙げられる。   As a preferable etching solution of the present invention, hydrogen fluoride (A) 0.05 to 7 mass%, ammonium fluoride (B) 1 to 45 mass%, and pKa 4.5 to 6 based on the total weight of the etching solution. Etching solution of silicon oxide film containing 0.1 to 3 mol / kg of salt (C) composed of acid (C1) of .5 and base (C2) having a pKa of 10.5 or more and residual water.

本発明のエッチング液には、さらに、界面活性剤(E)を添加してもよい。界面活性剤(E)は、疎水性表面(Si表面、Poly−Si表面、レジスト表面等)に対して濡れ性を増し、パターンの形状によっては薬液がいきわたらない場合等を防ぐために使用できる。その種類は、カチオン系界面活性剤(E1)、アニオン系界面活性剤(E2)、ノニオン系界面活性剤(E3)等、特に限定されない。カチオン系界面活性剤(E1)としては、例えば、C17NH等のアミン類が挙げられ、アニオン系界面活性剤(E2)としては、例えば、C17COOH等の炭化水素系カルボン酸、C17SOH等の炭化水素系スルホン酸、H(CFCOOH等のフッ素系カルボン酸等が挙げられ、ノニオン系界面活性剤(E3)としては、例えば、ポリオキシアルキレンアルキルエーテル等のエーテル類等が挙げられる。A surfactant (E) may be further added to the etching solution of the present invention. The surfactant (E) can be used to increase wettability with respect to a hydrophobic surface (Si surface, Poly-Si surface, resist surface, etc.) and prevent a case where a chemical solution does not spread depending on the shape of the pattern. The kind is not specifically limited, such as a cationic surfactant (E1), an anionic surfactant (E2), and a nonionic surfactant (E3). Examples of the cationic surfactant (E1) include amines such as C 8 H 17 NH 2 , and examples of the anionic surfactant (E2) include hydrocarbons such as C 8 H 17 COOH. Examples thereof include carboxylic acids, hydrocarbon sulfonic acids such as C 8 H 17 SO 3 H, fluorine-based carboxylic acids such as H (CF 2 ) 6 COOH, and the nonionic surfactant (E3) includes, for example, poly And ethers such as oxyalkylene alkyl ether.

界面活性剤(E)の添加量(濃度)は、特に限定されないが、エッチング液の全重量に対して2000massppm以下、好ましくは10〜1500massppm、より好ましくは50〜1200massppmとすればよい。   The addition amount (concentration) of the surfactant (E) is not particularly limited, but may be 2000 massppm or less, preferably 10 to 1500 massppm, more preferably 50 to 1200 massppm with respect to the total weight of the etching solution.

本発明のエッチング液は、フッ化水素酸(A)、フッ化アンモニウム(B)、フッ化水素酸(pKa=3.17)より大きいpKaを有する酸(C1)とアンモニア(pKa=9.24)より大きいpKaを有する塩基(C2)とからなる塩(C)及び水(D)を混合することにより製造される。必要に応じて前記界面活性剤(E)を混合してもよい。なお、混合方法は特に限定はなく公知の方法を採用できる。   The etching solution of the present invention includes hydrofluoric acid (A), ammonium fluoride (B), acid (C1) having a pKa larger than hydrofluoric acid (pKa = 3.17), and ammonia (pKa = 9.24). ) Prepared by mixing a salt (C) consisting of a base (C2) having a larger pKa and water (D). You may mix the said surfactant (E) as needed. The mixing method is not particularly limited, and a known method can be adopted.

本発明のエッチング液のシリコン酸化膜を含むウエハへの適用は、シリコン酸化膜をエッチング除去できる限り特に限定されず、塗布、浸漬、噴霧、噴射等の任意の方法を例示できる。特に、経時的な組成変化が少なくエッチングレートの変化が少ないという利点を利用することから、ウエハをエッチング液へ浸漬する方法(バッチ式装置)、及び、ウエハへエッチング液を噴射する方法(枚葉式装置)が好適である。   The application of the etching solution of the present invention to a wafer including a silicon oxide film is not particularly limited as long as the silicon oxide film can be removed by etching, and any method such as coating, dipping, spraying, and spraying can be exemplified. In particular, since the advantage that the composition change with time is small and the change in etching rate is small is utilized, a method of immersing a wafer in an etching solution (batch type apparatus) and a method of injecting an etching solution onto a wafer (single wafer) Type device) is preferred.

本発明のエッチング液の適用温度は、15〜90℃程度、好ましくは室温付近であり、この程度の温度でエッチング液をウエハに適用することにより、好適にシリコン酸化膜をエッチングすることができる。エッチング液の適用時間は、シリコン酸化膜の膜厚等にもよるが、一般に5秒から30分程度である。   The application temperature of the etching solution of the present invention is about 15 to 90 ° C., preferably around room temperature, and the silicon oxide film can be suitably etched by applying the etching solution to the wafer at this temperature. The application time of the etching solution is generally about 5 seconds to 30 minutes, although it depends on the thickness of the silicon oxide film.

本発明のエッチング液で処理して得られるエッチング処理物は、超純水などでリンスしてもよい。   The etched product obtained by treating with the etching solution of the present invention may be rinsed with ultrapure water or the like.

以下に実施例を示し、本発明の特徴を明確にする。本発明はこれら実施例に限定されるものではない。   Examples are given below to clarify the features of the present invention. The present invention is not limited to these examples.

実施例1〜3及び比較例1:蒸発試験
50mass%のフッ化水素酸(A)、40mass%のフッ化アンモニウム(B)(HFを0.07mass%含有)、表1に示す酸と塩基とからなる塩(C)、及び水(D)を所定の濃度で混合してエッチング液400gを調製した。HF濃度は、添加したフッ化アンモニウム(B)に含まれているフッ酸量の不足分を50mass%のフッ化水素酸(A)で補って調整した。また、塩(C)の調製に使用した酸及び塩基は、酢酸は100mass%濃度のものを、CHCHNHは70mass%水溶液、(CHNOHは25mass%水溶液を使用した。
Examples 1-3 and Comparative Example 1: Evaporation test 50 mass% hydrofluoric acid (A), 40 mass% ammonium fluoride (B) (containing 0.07 mass% HF), acids and bases shown in Table 1 400 g of an etching solution was prepared by mixing salt (C) and water (D) at a predetermined concentration. The HF concentration was adjusted by supplementing the shortage of hydrofluoric acid contained in the added ammonium fluoride (B) with 50 mass% hydrofluoric acid (A). The acid and base used in the preparation of salt (C) is acetic acid ones 100 mass% concentration, CH 3 CH 2 NH 2 is 70 mass% aqueous solution, (CH 3) 3 NOH was used 25 mass% aqueous solution.

[エッチング液の重量測定]
調製したエッチング液の半分を密閉した容器に保存した。残り半分は、直径8cmの円筒容器に入れ、容器内の液の重量(初期重量)を測定した。その後、ドラフト内で所定時間放置試験を実施した。所定時間放置試験後に再度容器内の重量(放置後重量)を測定した。放置試験時のドラフト内温度は18〜22℃、湿度は25〜35%とした。
[Weight measurement of etchant]
Half of the prepared etching solution was stored in a sealed container. The other half was placed in a cylindrical container having a diameter of 8 cm, and the weight of the liquid in the container (initial weight) was measured. Thereafter, a standing test was carried out for a predetermined time in a draft. After the standing test for a predetermined time, the weight in the container (weight after standing) was measured again. The temperature in the draft during the standing test was 18 to 22 ° C., and the humidity was 25 to 35%.

[エッチングレートの測定方法]
密閉容器に保存したエッチング液とドラフトで放置試験を行ったエッチング液は別々の容器に移し替えて恒温槽で液温を25℃に調整した。エッチングレートの測定は、膜厚が約1000Åの1.5cm×1.2cmの熱酸化膜ピース(薄膜)にて行った。
[Measurement method of etching rate]
The etching solution stored in the hermetically sealed container and the etching solution that had been left in the draft were transferred to separate containers, and the liquid temperature was adjusted to 25 ° C. in a thermostatic bath. The etching rate was measured with a 1.5 cm × 1.2 cm thermal oxide film piece (thin film) having a film thickness of about 1000 mm.

初期の膜厚を測定後にそれぞれの熱酸化膜ピースを一定時間(2.5分、5分、10分)薬液に浸漬し、その後、水で薬液をリンスし、窒素で乾燥させた後に各ピースの膜厚を測定した。浸漬前後の膜厚の差をエッチング量とし、縦軸をエッチング量、横軸をエッチング時間としたときにその傾きをエッチングレートとした。密閉容器に保存した液のエッチングレートを初期熱酸化膜エッチングレート(初期ER)とし、放置試験に用いた液のエッチングレートを放置後熱酸化膜のエッチングレート(放置後ER)とした。   After measuring the initial film thickness, each thermal oxide film piece is immersed in a chemical solution for a fixed time (2.5 minutes, 5 minutes, 10 minutes), then rinsed with water and dried with nitrogen before each piece. The film thickness of was measured. The difference in film thickness before and after immersion was taken as the etching amount, the vertical axis being the etching amount, and the horizontal axis being the etching time, the slope being the etching rate. The etching rate of the liquid stored in the sealed container was defined as an initial thermal oxide film etching rate (initial ER), and the etching rate of the liquid used in the standing test was defined as the etching rate of the thermal oxide film after standing (ER after standing).

膜厚の測定は、ナノスペック3000AF−T(ナノメトリクスジャパン(株)製)を用いた。   For the measurement of the film thickness, Nanospec 3000AF-T (manufactured by Nanometrics Japan Co., Ltd.) was used.

また、エッチングレート(ER)増加倍率は、以下の式にて計算した。   Moreover, the etching rate (ER) increase rate was calculated by the following formula.

ER増加倍率=[放置後熱酸化膜エッチングレート(放置後ER)]/ER increase ratio = [thermal oxide film etching rate after standing (ER after standing)] /
[初期熱酸化膜エッチングレート(初期ER)][Initial thermal oxide film etching rate (initial ER)]

実施例1〜3及び比較例1の組成を表1に、結果を表2に示す。   The compositions of Examples 1 to 3 and Comparative Example 1 are shown in Table 1, and the results are shown in Table 2.

Figure 0005423788
Figure 0005423788

Figure 0005423788
Figure 0005423788

ドラフト内薬液放置によるエッチングレート増加倍率は、酢酸とエチルアミンとからなる塩、酢酸とテトラメチルアンモニウムハイドロオキサイドとからなる塩を添加することで、無添加のものに比べて低減することができた。   The rate of increase in the etching rate due to standing in the draft chemical solution could be reduced by adding a salt composed of acetic acid and ethylamine and a salt composed of acetic acid and tetramethylammonium hydroxide as compared with those without addition.

実施例4〜5及び参考例1:蒸発試験
エッチング液中のNHF濃度が2mass%となるように調整し、NHF濃度、塩(C)の種類、塩(C)の添加量を表3に示すように調整したこと以外は実施例1〜3及び比較例1と同様に、実施例4〜5及び参考例1のエッチング液を調製した。なお、酢酸及びCHCHNHは実施例1〜3及び比較例1と同じものを使用し、コリンは44mass%水溶液を使用した。
Examples 4 to 5 and Reference Example 1: Evaporation test The NH 4 F concentration in the etching solution was adjusted to 2 mass%, and the NH 4 F concentration, the type of salt (C), and the amount of salt (C) added were adjusted. Etching liquids of Examples 4 to 5 and Reference Example 1 were prepared in the same manner as Examples 1 to 3 and Comparative Example 1 except that adjustment was performed as shown in Table 3. Incidentally, acetic acid and CH 3 CH 2 NH 2 was the same as used in Examples 1-3 and Comparative Example 1, Choline was used 44Mass% aqueous solution.

実施例4〜5及び参考例1の組成を表3に、結果を表4に示す。   The compositions of Examples 4 to 5 and Reference Example 1 are shown in Table 3, and the results are shown in Table 4.

Figure 0005423788
Figure 0005423788

Figure 0005423788
Figure 0005423788

NHF濃度を2mass%とした場合にも、酢酸とテトラメチルアンモニウムハイドロオキサイドとからなる塩、酢酸とコリンとからなる塩を添加することで、無添加のものに比べてエッチングレート増加倍率を低減することができ、実施例1〜3及び比較例1と同様の結果が得られた。Even when the NH 4 F concentration is 2 mass%, by adding a salt composed of acetic acid and tetramethylammonium hydroxide or a salt composed of acetic acid and choline, the rate of increase in the etching rate can be increased compared to the case of no addition. The same results as in Examples 1 to 3 and Comparative Example 1 were obtained.

実施例6〜7及び比較例2:水希釈試験
薬液蒸発試験に示したのと同様の薬液調合法により各薬液を1000g調合し、表5に示す所定の量で水と混合して薬液200gを調製し、25℃におけるエッチングレートを測定した。
Examples 6 to 7 and Comparative Example 2: Water dilution test Each chemical solution was prepared in an amount of 1000 g by the same chemical solution preparation method as shown in the chemical solution evaporation test, and 200 g of the chemical solution was mixed with water in a predetermined amount shown in Table 5. The etching rate at 25 ° C. was prepared.

[エッチングレートの測定方法]
密閉容器に保存したエッチング液の温度を恒温槽で25℃に調整し、これに1.5cm×1.2cmの熱酸化膜ピース(薄膜)を初期膜厚測定後に各薬液に5分間浸漬し、その後、水で薬液をリンスし窒素で乾燥させた後に各ピースの膜厚を測定した。そして、浸漬前後の膜厚の差をエッチング量とし、エッチング量をエッチング時間で割ってエッチングレートとした。
[Measurement method of etching rate]
The temperature of the etching solution stored in the sealed container is adjusted to 25 ° C. in a thermostatic bath, and a 1.5 cm × 1.2 cm thermal oxide film piece (thin film) is immersed in each chemical solution for 5 minutes after the initial film thickness measurement, Then, after rinsing the chemical with water and drying with nitrogen, the film thickness of each piece was measured. Then, the difference in film thickness before and after immersion was taken as the etching amount, and the etching amount was divided by the etching time to obtain the etching rate.

実施例6〜7及び比較例2の組成を表5に、結果を表6に示す。   The compositions of Examples 6 to 7 and Comparative Example 2 are shown in Table 5, and the results are shown in Table 6.

Figure 0005423788
Figure 0005423788

Figure 0005423788
Figure 0005423788

酢酸とテトラメチルハイドロオキサイドとからなる塩を0.5mol/kg添加したバッファードフッ酸(実施例6)では、塩を添加しないもの(比較例2)に比べるとエッチングレートの変動は少なかった。また、酢酸とテトラメチルハイドロオキサイドとからなる塩を1mol/kg添加したバッファードフッ酸(実施例7)は、水で希釈してもエッチングレートの変動はほとんどなく、実施例6と比べても、エッチングレートの変動を抑制できた。   In the buffered hydrofluoric acid (Example 6) to which 0.5 mol / kg of a salt composed of acetic acid and tetramethyl hydroxide was added, the variation in the etching rate was small compared to that without the salt (Comparative Example 2). In addition, buffered hydrofluoric acid (Example 7) to which a salt of acetic acid and tetramethyl hydroxide was added at 1 mol / kg hardly changed the etching rate even when diluted with water, and compared with Example 6. The fluctuation of the etching rate could be suppressed.

実施例8〜11及び比較例3〜4:添加した塩の種類・添加量と熱酸化膜エッチングレートとの関係
50mass%のフッ化水素酸(A)、40mass%のフッ化アンモニウム(B)(HFを0.07mass%含有)、表7に示す酸と塩基とからなる塩(C)、及び水(D)を所定の濃度で混合してエッチング液200gを調製した。HF濃度は、0.25mass%、0.5mass%、0.75mass%又は1mass%になるように、50mass%のフッ化水素酸の添加量を変えて調製した。なお、40mass%のフッ化アンモニウム中にはもともと0.07mass%のフッ化水素が含まれているので、この量を加味してHF濃度を調整した。また、酢酸は100mass%のものを、CHCHNHは70mass%水溶液、(CHNOHは25mass%水溶液を使用した。
Examples 8 to 11 and Comparative Examples 3 to 4: Relationship between kind and amount of added salt and thermal oxide film etching rate 50 mass% hydrofluoric acid (A), 40 mass% ammonium fluoride (B) ( 200 g of etching solution was prepared by mixing HF (containing 0.07 mass%), a salt (C) composed of an acid and a base shown in Table 7, and water (D) at a predetermined concentration. The HF concentration was adjusted by changing the addition amount of 50 mass% hydrofluoric acid so that the concentration was 0.25 mass%, 0.5 mass%, 0.75 mass%, or 1 mass%. Since 40 mass% ammonium fluoride originally contained 0.07 mass% hydrogen fluoride, the HF concentration was adjusted by taking this amount into account. Further, acetic acid was 100 mass%, CH 3 CH 2 NH 2 was 70 mass% aqueous solution, and (CH 3 ) 4 NOH was 25 mass% aqueous solution.

[エッチングレートの測定方法]
1.5cm×1.2cmの熱酸化膜ピース(薄膜)を初期膜厚測定後に各薬液に5分間浸漬し、その後、水で薬液をリンスし窒素で乾燥させた後に各ピースの膜厚を測定した。そして、浸漬前後の膜厚の差をエッチング量とし、エッチング量をエッチング時間で割ってエッチングレートとした。
[Measurement method of etching rate]
After measuring the initial film thickness, a 1.5cm x 1.2cm thermal oxide film piece (thin film) is immersed in each chemical solution for 5 minutes, then rinsed with water and dried with nitrogen, and then measured the film thickness of each piece. did. Then, the difference in film thickness before and after immersion was taken as the etching amount, and the etching amount was divided by the etching time to obtain the etching rate.

実施例8〜11及び比較例3〜4のNHF濃度、塩の種類及び塩の添加量を表7に、HF濃度及び結果を表8に示す。なお、y=ax+bの関係式におけるa及びbは、3種類のHF濃度におけるエッチングレートを測定し、その結果から最小自乗法により算出した(3点測定)。Table 7 shows the NH 4 F concentration, salt type, and salt addition amount of Examples 8 to 11 and Comparative Examples 3 to 4 , and Table 8 shows the HF concentration and the results. Note that a and b in the relational expression y = ax + b were obtained by measuring the etching rates at three types of HF concentrations and calculating the result by the least square method (three-point measurement).

Figure 0005423788
Figure 0005423788

Figure 0005423788
Figure 0005423788

実施例8〜11及び比較例3〜4の結果について、HF濃度を横軸に、エッチングレートを縦軸にとったグラフを図1に示す。   About the result of Examples 8-11 and Comparative Examples 3-4, the graph which took the HF density | concentration on the horizontal axis and took the etching rate on the vertical axis | shaft is shown in FIG.

比較例3(塩無添加)、実施例10(0.5mol/kg(CHCOOH+(CHNOH)添加)、及び実施例11(1mol/kg(CHCOOH+(CHNOH)添加)に示すように、塩の添加濃度が高いほどエッチングレートの傾きは小さくなっている。Comparative Example 3 (no salt added), Example 10 (0.5 mol / kg (CH 3 COOH + (CH 3 ) 4 NOH) added), and Example 11 (1 mol / kg (CH 3 COOH + (CH 3 ) 4 NOH) As shown in () Addition), the slope of the etching rate decreases as the salt concentration increases.

先に示した蒸発試験の比較例1(塩無添加・比較例3に対応)、実施例1(1mol/kg(CHCOOH+CHCHNH)添加・実施例8に対応)、実施例2(0.5mol/kg(CHCOOH+(CHNOH)添加・実施例10に対応)、及び実施例3(1mol/kg(CHCOOH+(CHNOH)添加・実施例11に対応)のエッチングレート増加倍率と、図1に示すエッチングレートの傾きとを比べたものを表9に示す。Comparative Example 1 (corresponding to Comparative Example 3 with no addition of salt), Example 1 (corresponding to Addition of 1 mol / kg (CH 3 COOH + CH 3 CH 2 NH 2 ) and Corresponding to Example 8), Example 2 (0.5 mol / kg (CH 3 COOH + (CH 3 ) 4 NOH) addition / corresponding to Example 10) and Example 3 (1 mol / kg (CH 3 COOH + (CH 3 ) 4 NOH) addition / Example) Table 9 shows a comparison of the etching rate increase magnification (corresponding to 11) and the slope of the etching rate shown in FIG.

Figure 0005423788
Figure 0005423788

表9から、エッチングレートの傾きが小さいほど、蒸発試験によるエッチングレートの増加倍率は小さくなっていることがわかる。   From Table 9, it can be seen that the smaller the slope of the etching rate, the smaller the increase rate of the etching rate by the evaporation test.

また、先に示した水希釈試験の比較例2(塩無添加・比較例3に対応)、実施例6(0.5mol/kg(CHCOOH+(CHNOH)添加・実施例10に対応)、及び実施例7(1mol/kg(CHCOOH+(CHNOH)添加・実施例11に対応)の初期のエッチングレート(希釈しない場合)とバッファードフッ酸:水=90:10で希釈した場合のエッチングレートの比(ER低下倍率;バッファードフッ酸:水=90:10で希釈した場合のER/初期のER)と、図1に示すエッチングレートの傾きとを比べたものを表10に示す。Further, Comparative Example 2 (corresponding to no salt addition / Comparative Example 3) and Example 6 (0.5 mol / kg (CH 3 COOH + (CH 3 ) 4 NOH) addition / Example 10) of the water dilution test shown above. ), And Example 7 (1 mol / kg (CH 3 COOH + (CH 3 ) 4 NOH) added / corresponds to Example 11) and initial etching rate (when not diluted) and buffered hydrofluoric acid: water = 90 : Ratio of etching rate when diluted by 10 (ER reduction ratio; buffered hydrofluoric acid: water = ER when diluted by 90: 10 / initial ER) and the slope of the etching rate shown in FIG. Table 10 shows the results.

Figure 0005423788
Figure 0005423788

表10から、エッチングレートの傾きが小さいほど、水希釈試験によるエッチングレートの低下倍率が少なくなっていることがわかる。   From Table 10, it can be seen that the smaller the slope of the etching rate, the smaller the reduction rate of the etching rate by the water dilution test.

このように、HF濃度と熱酸化膜エッチング量から求めた傾きを調べることで、薬液蒸発や希釈にともなうエッチング量の変動の大小を予測できる。   As described above, by examining the slope obtained from the HF concentration and the thermal oxide film etching amount, the magnitude of the variation in the etching amount due to the evaporation and dilution of the chemical solution can be predicted.

実施例12〜21及び比較例5〜11:添加した塩の種類・濃度と熱酸化膜エッチングレートとの関係2
実施例8〜11及び比較例3〜4と同様にエッチング液を調製し、実施例8〜11及び比較例3〜4と同様の方法でエッチングレートを測定した。
Examples 12 to 21 and Comparative Examples 5 to 11: Relationship 2 between kind and concentration of added salt and thermal oxide film etching rate
Etching liquids were prepared in the same manner as in Examples 8 to 11 and Comparative Examples 3 to 4, and the etching rate was measured in the same manner as in Examples 8 to 11 and Comparative Examples 3 to 4.

実施例12〜21及び比較例5〜11のNHF濃度、塩の種類、塩の添加量、界面活性剤の種類及び界面活性剤の添加量を表11に、HF濃度及び結果を表12に示す。なお、ここでも、実施例8〜11及び比較例3〜4と同様に、y=ax+bの関係式におけるa及びbは、3種類のHF濃度におけるエッチングレートを測定し、その結果から最小自乗法により算出した(3点測定)。The NH 4 F concentration, the salt type, the salt addition amount, the surfactant type and the surfactant addition amount of Examples 12 to 21 and Comparative Examples 5 to 11 are shown in Table 11, and the HF concentration and results are shown in Table 12. Shown in In this case, as in Examples 8 to 11 and Comparative Examples 3 to 4, a and b in the relational expression y = ax + b are the etching rates at three HF concentrations, and the least square method is obtained from the results. (3-point measurement).

Figure 0005423788
Figure 0005423788

Figure 0005423788
Figure 0005423788

表12からも、表10と同様、エッチングレートの傾きが小さいほど、水希釈試験によるエッチングレートの低下倍率が少なくなっていることがわかる。
From Table 12, it can be seen that, as in Table 10, the smaller the slope of the etching rate, the smaller the reduction rate of the etching rate by the water dilution test.

Claims (14)

(A)フッ化水素酸、
(B)フッ化アンモニウム、
(C)フッ化水素酸(pKa=3.17)より大きいpKaを有する酸(C1)とアンモニア(pKa=9.24)より大きいpKaを有する塩基(C2)とからなる塩、及び
(D)水
を含むエッチング液。
(A) hydrofluoric acid,
(B) ammonium fluoride,
(C) a salt comprising an acid (C1) having a pKa greater than hydrofluoric acid (pKa = 3.17) and a base (C2) having a pKa greater than ammonia (pKa = 9.24), and (D) Etching solution containing water.
酸(C1)のpKaが、3.17より大きく、7未満である請求項1に記載のエッチング液。 The etching solution according to claim 1, wherein the pKa of the acid (C1) is greater than 3.17 and less than 7. 酸(C1)が、蟻酸(pKa=3.75)、酢酸(pKa=4.56)、マロン酸(2段目のpKa=5.28)、クエン酸(3段目のpKa=5.69)、マレイン酸(2段目のpKa=5.83)、2−(N−モルホリノ)エタンスルホン酸(pKa=6.1)及び炭酸(1段目のpKa=6.35)よりなる群から選ばれる少なくとも1種である請求項1又は2に記載のエッチング液。 Acid (C1) is formic acid (pKa = 3.75), acetic acid (pKa = 4.56), malonic acid (second stage pKa = 5.28), citric acid (third stage pKa = 5.69). ), Maleic acid (second stage pKa = 5.83), 2- (N-morpholino) ethanesulfonic acid (pKa = 6.1) and carbonic acid (first stage pKa = 6.35). The etching solution according to claim 1 or 2, which is at least one selected. 酸(C1)が、酢酸である請求項1〜3のいずれかに記載のエッチング液。 The etching solution according to claim 1, wherein the acid (C1) is acetic acid. 塩基(C2)が、第一アミン(C2a)、第二アミン(C2b)、第三アミン(C2c)及び第四級アンモニウム(C2d)よりなる群から選ばれる少なくとも1種である請求項1〜4のいずれかに記載のエッチング液。 The base (C2) is at least one selected from the group consisting of a primary amine (C2a), a secondary amine (C2b), a tertiary amine (C2c), and a quaternary ammonium (C2d). The etching liquid in any one of. 第一アミン(C2a)が、メチルアミン(pKa=10.6)、エチルアミン(pKa=10.6)、プロピルアミン(pKa=10.6)、ブチルアミン(pKa=10.6)、ペンチルアミン(pKa=10.0)、エタノールアミン(pKa=9.3)、プロパノールアミン(pKa=9.3)、ブタノールアミン(pKa=9.3)、メトキシエチルアミン(pKa=10.0)及びメトキシプロピルアミン(pKa=10.0)よりなる群から選ばれる少なくとも1種である請求項5に記載のエッチング液。 Primary amine (C2a) is methylamine (pKa = 10.6), ethylamine (pKa = 10.6), propylamine (pKa = 10.6), butylamine (pKa = 10.6), pentylamine (pKa) = 10.0), ethanolamine (pKa = 9.3), propanolamine (pKa = 9.3), butanolamine (pKa = 9.3), methoxyethylamine (pKa = 10.0) and methoxypropylamine ( 6. The etching solution according to claim 5, wherein the etching solution is at least one selected from the group consisting of pKa = 10.0). 第二アミン(C2b)が、ジメチルアミン(pKa=10.8)、ジエチルアミン(pKa=10.9)及びジプロピルアミン(pKa=10.8)よりなる群から選ばれる少なくとも1種である請求項5又は6に記載のエッチング液。 The secondary amine (C2b) is at least one selected from the group consisting of dimethylamine (pKa = 10.8), diethylamine (pKa = 10.9) and dipropylamine (pKa = 10.8). The etching solution according to 5 or 6. 第三アミン(C2c)が、トリメチルアミン(pKa=9.80)及びトリエチルアミン(pKa=10.72)よりなる群から選ばれる少なくとも1種である請求項5〜7のいずれかに記載のエッチング液。 The etching solution according to any one of claims 5 to 7, wherein the tertiary amine (C2c) is at least one selected from the group consisting of trimethylamine (pKa = 9.80) and triethylamine (pKa = 10.72). 第四級アンモニウム(C2d)が、テトラメチルアンモニウムハイドロオキサイド(pKa=14.0)、テトラエチルアンモニウムハイドロオキサイド(pKa=14.0)及びコリン(pKa=13.2)よりなる群から選ばれる少なくとも1種である請求項5〜8のいずれかに記載のエッチング液。 Quaternary ammonium (C2d) is at least one selected from the group consisting of tetramethylammonium hydroxide (pKa = 14.0), tetraethylammonium hydroxide (pKa = 14.0) and choline (pKa = 13.2). The etching solution according to claim 5, which is a seed. 塩基(C2)が、テトラメチルアンモニウムハイドロオキサイドである請求項1〜5のいずれかに記載のエッチング液。 The etching solution according to any one of claims 1 to 5, wherein the base (C2) is tetramethylammonium hydroxide. さらに、界面活性剤(E)を含む請求項1〜10のいずれかに記載のエッチング液。 Furthermore, the etching liquid in any one of Claims 1-10 containing surfactant (E). (A)フッ化水素酸、
(B)フッ化アンモニウム、
(C)フッ化水素酸(pKa=3.17)より大きいpKaを有する酸(C1)とアンモニア(pKa=9.24)より大きいpKaを有する塩基(C2)とからなる塩、及び
(D)水
を混合することを特徴とする請求項1〜11のいずれかに記載のエッチング液の製造方法。
(A) hydrofluoric acid,
(B) ammonium fluoride,
(C) a salt comprising an acid (C1) having a pKa greater than hydrofluoric acid (pKa = 3.17) and a base (C2) having a pKa greater than ammonia (pKa = 9.24), and (D) Water is mixed, The manufacturing method of the etching liquid in any one of Claims 1-11 characterized by the above-mentioned.
請求項1〜11のいずれかに記載のエッチング液を用いて被エッチング物をエッチング処理することを特徴とするエッチング方法。 An etching method for etching an object to be etched using the etching solution according to claim 1. 請求項1〜11のいずれかに記載のエッチング液を用いて被エッチング物をエッチング処理することを特徴とするエッチング処理物の製造方法。 The manufacturing method of the etching processed material characterized by etching a to-be-etched object using the etching liquid in any one of Claims 1-11.
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CN111825480B (en) * 2020-08-13 2022-11-04 西藏大学 Ultraviolet-resistant super-hydrophobic anti-freezing material and preparation method thereof
WO2022043111A1 (en) 2020-08-25 2022-03-03 Basf Se Composition, its use and a process for removing post-etch residues
CN114369460B (en) * 2021-12-09 2023-07-11 湖北兴福电子材料股份有限公司 Etching solution for improving silicon dioxide etching uniformity of concave groove structure
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