A method for preparing a metal etching solution

Abstract

The application discloses a preparation method of a metal etching solution and belongs to the technical field of semiconductor element processing. The metal etching solution is prepared by mixing and stirring an oxidizing agent, an oxalate, an amino carboxylic acid, a phosphorous acid chelating agent, a polyoxypropylene polyoxyethylene ether, an anticorrosive agent, a stabilizer, an inorganic alkali and water. The stabilizer is prepared by reacting mercapto benzothiazole, copper nitrate and DMF at 30-40 DEG C, adding maleic acid triethanolamine double ester and octavinyl octasilsesquioxane and triethanolamine at 60-70 DEG C, and removing DMF through reduced pressure distillation. The mercapto benzothiazole forms a protective film on the surface of the metal to prevent the metal from being further corroded. The addition of the silsesquioxane forms a specific bacteriostatic layer on the surface of the metal due to the special chemical structure, thereby further enhancing the bacteriostatic performance of the etching solution.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor element processing, in particular to a preparation method of metal etching solution. BACKGROUND

[0002] Metal etching is a chemical or mechanical processing technique that processes a shiny metal surface into a rough crystal surface. In recent decades, with the development of economy and society, the application of metal etching technology has been increasingly valued by people. As a precise and scientific chemical processing technology, chemical etching is widely used on various metal materials. During the etching process of metal in the etching solution, firstly, the crystal grains on the surface of the metal part are dissolved; secondly, the dissolution also occurs on the grain boundaries, and generally the grain boundaries and crystal grains are dissolved at different dissolution rates.

[0003] Chinese patent CN113667979A discloses a copper-molybdenum metal etching solution and its application. The composition of the copper-molybdenum metal etching solution includes, by weight percentage: 1-21wt% of hydrogen peroxide, 0.01-10wt% of a shape control agent, 0.01-5wt% of an etching stabilizer, 1-13wt% of a chelating agent, 0.01-8wt% of a pH adjuster, and 0.01-2.39wt% of an etching additive, and the balance of deionized water.

[0004] Chinese patent CN116970952A relates to the field of metal etching technology, especially to the field of IPCC23F1, and further relates to a copper metal etching solution composition and its use method. It includes: A component and B component added by 0.05-0.3% of A component weight when copper ions increase by 100ppm.

[0005] Chinese patent CN114438495A provides a metal etching solution, which includes: 5 to 30wt% of an oxidizing agent; 2.5 to 15wt% of an amino acid; 2.5 to 15wt% of a phosphate; 2 to 15wt% of a non-amino acid carboxylic acid; and the balance of water. In the present application, hydrogen peroxide and persulfate are selected as the oxidizing agent, and the weight ratio between the two is controlled between 1:1.5 and 1:5.

[0006] The etching solution prepared by the above patents and prior art has the disadvantages of large underCut and poor bacteriostatic performance. SUMMARY

[0007] To solve the above problems, the present application provides a preparation method of metal etching solution, and the operation steps are as follows:

[0008] S1: 1-5 parts of an oxidizing agent, 20-30 parts of water are stirred and mixed uniformly;

[0009] S2: 1-5 parts of oxalate, 5-10 parts of aminocarboxylic acid, 50-70 parts of water are added and stirred to mix uniformly;

[0010] S3: 0.5-1.5 parts of phosphite chelating agent, 0.01-0.5 parts of surfactant polyoxypropylene polyoxyethylene ether, 0.08-1 parts of corrosion inhibitor, 0.002-0.05 parts of stabilizer, 0.2-2.5 parts of inorganic base are continuously added and stirred to mix uniformly to obtain a metal etching solution.

[0011] As a preferred solution, the oxidizing agent is persulfate or hydrogen peroxide.

[0012] As a preferred solution, the oxalate is one of ammonium oxalate, sodium oxalate, potassium oxalate.

[0013] As a preferred solution, the aminocarboxylic acid is one of alanine, valine, isoleucine, glycine.

[0014] As a preferred solution, the phosphite chelating agent is one of 1-hydroxypropylidene-1,1'-diphosphonic acid, 1-hydroxybutylidene-1,1'-diphosphonic acid, aminotri(methylene) phosphonic acid, ethylenediamine(tetramethylene phosphonic acid), 1-hydroxyethane-1,1'-diphosphonic acid.

[0015] As a preferred solution, the corrosion inhibitor is one of 4-carboxybenzotriazole, 5-carboxybenzotriazole, 5-methylbenzotriazole, 5-chlorobenzotriazole, isocitric acid, tartaric acid, malic acid, adenine, guanine, guanine nucleoside, cytosine, thymine, uracil, quinaldic acid, bipyridine, phenanthroline, benzotriazole, citric acid.

[0016] As a preferred solution, the inorganic base is one of ammonia, sodium hydroxide, potassium hydroxide.

[0017] As a preferred solution, the preparation method of the stabilizer is:

[0018] A1: 5-10 parts of mercaptobenzothiazole, 4-7 parts of copper nitrate, 100-130 parts of DMF are mixed and reacted at 30-40°C for 60-100 minutes;

[0019] A2: 2-5 parts of maleic acid triethanolamine double ester, 5-10 parts of octavinyl octasilsesquioxane, 3-6 parts of triethanolamine are added and reacted at 60-70°C for 100-130 minutes, and then DMF is removed by reduced pressure distillation, and vacuum drying to obtain the stabilizer.

[0020] As a preferred solution, the preparation method of the maleic acid triethanolamine double ester is:

[0021] According to mass parts, 14-22 parts of maleic anhydride are mixed with 31-53 parts of triethanolamine and then added to the reactor, and 1-4 parts of acetic acid is added to the reactor, and the reaction is carried out at 60-70°C for 100-130 minutes.

[0022] Reaction mechanism

[0023] The reaction mechanism of the stabilizer is:

[0024] The addition reaction of mercaptobenzothiazole / copper complex and maleic acid triethanolamine diester occurs; the addition reaction of mercaptobenzothiazole / copper complex and octavinyl octasilsesquioxane occurs; a metal etching liquid stabilizer is obtained.

[0025] 1. Reaction mechanism of benzothiazole copper complex

[0026] Coordination addition: the formation of benzothiazole copper complex involves the formation of a coordination covalent bond between mercaptobenzothiazole and copper ions. This complex can further undergo addition reaction with other compounds such as maleic acid triethanolamine diester to form more stable compounds.

[0027] Corrosion inhibition: mercaptobenzothiazole is a known high-efficiency corrosion inhibitor, especially for copper, its corrosion inhibition effect is mainly realized by forming a protective film on the metal surface to prevent further corrosion of the metal.

[0028] 2. Role of silsesquioxane

[0029] Provide stability: octavinyl octasilsesquioxane forms a network structure by addition reaction with benzothiazole copper complex through its multiple vinyl groups, which helps to increase the overall stability of the metal etching liquid.

[0030] Enhanced bacteriostatic effect: the addition of silsesquioxane can form a specific bacteriostatic layer on the metal surface due to its special chemical structure, further enhancing the bacteriostatic performance of the etching liquid.

[0031] Technical effects

[0032] The preparation method of a metal etching liquid of the present application, compared with the prior art, has the following remarkable effects:

[0033] 1. The stabilizer prepared by the present application can effectively improve the precision and uniformity of metal etching, and the use of this stabilized metal etching liquid can more accurately control the etching process, thereby obtaining more uniform etching effect, which is particularly important for the electronic industry;

[0034] 2. The stabilizer prepared by the present application prolongs the service life of the etching liquid, increases the stability, reduces the replacement frequency of the etching liquid, reduces the production cost, and also reduces the generation of chemical waste, which has positive significance for environmental sustainable development. DETAILED DESCRIPTION

[0035] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined inventive purpose, the following will be described in detail in combination with examples and comparative examples:

[0036] 1. Etching speed test: A Cu plate with a length of 1 cm x width of 1 cm x thickness of 1 mm is immersed in the etching solution prepared by the present application at room temperature for 10 minutes for etching; the Cu ion concentration obtained by the etching process is measured by an atomic absorption photometer, the dissolution amount per unit area is calculated, and then the dissolution speed, i.e. the etching speed, is obtained;

[0037] 2. Undercut length test:

[0038] On a 4 cm Si substrate with a thickness of 10 nm containing a thermal oxide film (SiO2), a 300 nm thick Ti stack is first deposited by sputtering, then a 300 nm thick Cu stack is deposited on the Ti / SiO2 / Si substrate, and a positive film type photosensitive resist resin coating (film thickness of 40 μm) is coated on the Cu / Ti / SiO2 / Si substrate to form a model by photoetching technology; After that, a Cu stack (film thickness of 20 μm) is deposited using electroplating method, and then a Ni stack (film thickness of 5 μm) and a Sn / Ag (97:3) stack (film thickness of 15 μm) are coated in sequence; Finally, the photosensitive resist resin coating is removed to obtain an evaluation semiconductor substrate;

[0039] The evaluation semiconductor substrate is cut into an evaluation sample with a length of 1 cm x width of 1 cm, which is immersed in the etching solution prepared by the present application at room temperature, and etched for 120-200%, i.e. after appropriate etching and over-etching, the over-etching treatment time is 20-100% of the appropriate etching time; After etching treatment, the upper side length of the rectangular Cu film remaining on the basic metal Ti film is observed and detected by scanning electron microscope, which is the undercut length;

[0040] Bacteriostatic rate test: Test according to WS / T650-2019 "Antibacterial and Bacteriostatic Effect Evaluation Method".

[0041] Example 1

[0042] A preparation method of a metal etching solution, the operation steps of which are as follows:

[0043] S1: 1 g of oxidizing agent, 20 g of water, and stirring and mixing uniformly;

[0044] S2: Add 1 g of oxalate, 5 g of aminocarboxylic acid, and 50 g of water, and stir and mix uniformly;

[0045] S3: continue to add 0.5 g of phosphorous acid chelating agent, 0.01 g of surfactant polyoxypropylene polyoxyethylene ether, 0.08 g of corrosion inhibitor, 0.002 g of stabilizer, 0.2 g of inorganic base, and stir to mix uniformly to obtain a metal etching solution.

[0046] The oxidizing agent is a persulfate salt.

[0047] The oxalate is ammonium oxalate.

[0048] The amino carboxylic acid is alanine.

[0049] The phosphorous acid chelating agent is 1-hydroxyisopropyl-1,1'-diphosphonic acid.

[0050] The corrosion inhibitor is 4-carboxybenzotriazole.

[0051] The inorganic base is ammonia.

[0052] The preparation method of the stabilizer is:

[0053] A1: mix 5 g of mercaptobenzothiazole, 4 g of copper nitrate, and 100 g of DMF, and react at 30°C for 60 minutes;

[0054] A2: add 2 g of maleic acid triethanolamine double ester, 5x10-3 g of octavinyl octasilsesquioxane, and 3 g of triethanolamine, and react at 60°C for 100 minutes, remove the DMF by vacuum distillation, and vacuum dry to obtain the stabilizer.

[0055] The preparation method of the maleic acid triethanolamine double ester is:

[0056] Mix 14 g of maleic anhydride and 31 g of triethanolamine, add to a reactor, add 1 g of acetic acid to the reactor, and react at 60°C for 100 minutes to obtain maleic acid triethanolamine double ester.

[0057] Example 2

[0058] A preparation method of a metal etching solution, the operation steps of which are:

[0059] S1: mix 2 g of oxidizing agent and 23 g of water, and stir to mix uniformly;

[0060] S2: add 2 g of oxalate, 6 g of amino carboxylic acid, and 55 g of water, and stir to mix uniformly;

[0061] S3: continue to add 0.8 g of phosphorous acid chelating agent, 0.2 g of surfactant polyoxypropylene polyoxyethylene ether, 0.5 g of corrosion inhibitor, 0.02 g of stabilizer, and 1 g of inorganic base, and stir to mix uniformly to obtain a metal etching solution.

[0062] The oxidizing agent is a persulfate salt.

[0063] The oxalate is sodium oxalate.

[0064] The aminocarboxylic acid is valine.

[0065] The phosphite chelating agent is 1-hydroxybutylidene-1,1'-diphosphonic acid.

[0066] The corrosion inhibitor is 5-carboxybenzotriazole.

[0067] The inorganic base is sodium hydroxide.

[0068] The preparation method of the stabilizer is:

[0069] A1: 6g of mercaptobenzothiazole, 5g of copper nitrate, 110g of DMF are mixed, and reacted at 35°C for 70 minutes;

[0070] A2: 3g of maleic acid triethanolamine double ester, 6x10-3g of octavinyl octasilsesquioxane, 4g of triethanolamine are added, and reacted at 65°C for 110 minutes, and then DMF is removed by vacuum distillation, and vacuum dried to obtain the stabilizer.

[0071] The preparation method of the maleic acid triethanolamine double ester is:

[0072] After 16g of maleic anhydride and 38g of triethanolamine are mixed and added to a reactor, 2g of acetic acid is added to the reactor, and reacted at 65°C for 110 minutes to obtain the maleic acid triethanolamine double ester.

[0073] Example 3

[0074] A preparation method of a metal etching solution, the operation steps of which are:

[0075] S1: 4g of an oxidizing agent, 28g of water are stirred and mixed uniformly;

[0076] S2: 4g of an oxalate, 8g of an aminocarboxylic acid, 65g of water are added and stirred and mixed uniformly;

[0077] S3: 1.3g of a phosphite chelating agent, 0.4g of a surfactant polyoxypropylene polyoxyethylene ether, 0.8g of a corrosion inhibitor, 0.04g of a stabilizer, 2g of an inorganic base are continuously added and stirred and mixed uniformly to obtain a metal etching solution.

[0078] The oxidizing agent is hydrogen peroxide.

[0079] The oxalate is sodium oxalate.

[0080] The aminocarboxylic acid is isoleucine.

[0081] The phosphite chelating agent is aminotri(methylene) phosphonic acid.

[0082] The anticorrosive agent is 5-methyl benzotriazole.

[0083] The inorganic base is sodium hydroxide.

[0084] The preparation method of the stabilizer is:

[0085] A1: 8 g of mercaptobenzothiazole, 6 g of copper nitrate, and 120 g of DMF are mixed and reacted at 35°C for 90 minutes;

[0086] A2: 4 g of maleic acid triethanolamine double ester, 8x10-3 g of octavinyl octasilsesquioxane, and 5 g of triethanolamine are added and reacted at 65°C for 120 minutes, and then DMF is removed by vacuum distillation, and vacuum drying is performed to obtain the stabilizer.

[0087] The preparation method of the maleic acid triethanolamine double ester is:

[0088] After 20 g of maleic anhydride and 48 g of triethanolamine are mixed and added to a reactor, 3 g of acetic acid is added to the reactor, and the mixture is reacted at 65°C for 120 minutes to obtain maleic acid triethanolamine double ester.

[0089] Example 4

[0090] A preparation method of a metal etching solution, the operation steps of which are:

[0091] S1: 5 g of an oxidizing agent, 30 g of water, are stirred and mixed uniformly;

[0092] S2: 5 g of an oxalate, 10 g of an aminocarboxylic acid, 70 g of water, are stirred and mixed uniformly;

[0093] S3: 1.5 g of a phosphite chelating agent, 0.5 g of a surfactant polyoxypropylene polyoxyethylene ether, 1 g of an anticorrosive agent, 0.05 g of a stabilizer, 2.5 g of an inorganic base, are continuously added and stirred and mixed uniformly to obtain a metal etching solution.

[0094] The oxidizing agent is hydrogen peroxide.

[0095] The oxalate is potassium oxalate.

[0096] The aminocarboxylic acid is glycine.

[0097] The phosphite chelating agent is ethylenediamine (tetramethylene phosphonic acid).

[0098] The anticorrosive agent is benzotriazole.

[0099] The inorganic base is potassium hydroxide.

[0100] The preparation method of the stabilizer is:

[0101] A1: 10 g of mercaptobenzothiazole, 7 g of copper nitrate, 130 g of DMF were mixed and reacted at 40°C for 100 minutes;

[0102] A2: 5 g of maleic acid triethanolamine double ester, 10 x 10-3 g of octavinyl octasilsesquioxane, 6 g of triethanolamine were added and reacted at 70°C for 130 minutes, and then DMF was removed by vacuum distillation, and vacuum drying was performed to obtain the stabilizer.

[0103] The preparation method of the maleic acid triethanolamine double ester is as follows:

[0104] After 22 g of maleic anhydride and 53 g of triethanolamine were mixed and added to a reactor, 4 g of acetic acid was added to the reactor, and the reaction was carried out at 70°C for 130 minutes to obtain maleic acid triethanolamine double ester.

[0105] Comparative Example 1

[0106] No stabilizer was added, and the other conditions were the same as in Example 1.

[0107] Comparative Example 2

[0108] No maleic acid triethanolamine double ester was added, and the other conditions were the same as in Example 1.

[0109] Comparative Example 3

[0110] No octavinyl octasilsesquioxane was added, and the other conditions were the same as in Example 1.

[0111] The test results are shown in Table 1.

[0112] Table 1

[0113]

[0114] Through analysis of the data of the above examples and comparative examples, the stabilizer prepared in the present application can effectively improve the bacteriostatic rate of the etching solution and reduce the undercut length.

[0115] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, and any equivalent embodiments with equivalent changes and modifications are still within the scope of the technical solution of the present application.

Claims

1. A method for preparing a metal etching solution, comprising the following steps: S1: Mix 1-5 parts oxidant and 20-30 parts water until homogeneous; S2: Add 1-5 parts oxalate, 5-10 parts aminocarboxylic acid, and 50-70 parts water, and stir to mix evenly; S3: Continue to add 0.5-1.5 parts of phosphorous acid chelating agent, 0.01-0.5 parts of surfactant polyoxypropylene polyoxyethylene ether, 0.08-1 parts of corrosion inhibitor, 0.002-0.05 parts of stabilizer, and 0.2-2.5 parts of inorganic alkali, stir and mix evenly to obtain metal etching solution; The stabilizer is prepared by reacting a mercaptobenzothiazole / copper complex with triethanolamine maleate diester and octavinyloctasilsesquioxane; the preparation method of the stabilizer is as follows: A1: Mix 5-10 parts by weight of mercaptobenzothiazole, 4-7 parts by weight of copper nitrate and 100-130 parts by weight of DMF, and react at 30-40°C for 60-100 minutes. A2: Add 2-5 parts of triethanolamine maleate diester, 5-10 parts of octavinyloctasilsesquioxane, and 3-6 parts of triethanolamine, react at 60-70℃ for 100-130 minutes, remove DMF by vacuum distillation, and dry under vacuum to obtain the stabilizer. The preparation method of the aforementioned triethanolamine maleate diester is as follows: By mass, 14-22 parts of maleic anhydride and 31-53 parts of triethanolamine are mixed and added to a reactor, and 1-4 parts of acetic acid are added to the reactor. The mixture is reacted at 60℃-70℃ for 100-130 minutes to obtain triethanolamine maleate diester.

2. The method for preparing a metal etching solution according to claim 1, characterized in that: The oxidant is persulfate or hydrogen peroxide.

3. The method for preparing a metal etching solution according to claim 1, characterized in that: The oxalate mentioned is one of ammonium oxalate, sodium oxalate, and potassium oxalate.

4. The method for preparing a metal etching solution according to claim 1, characterized in that: The aminocarboxylic acid is one of alanine, valine, isoleucine, and glycine.

5. The method for preparing a metal etching solution according to claim 1, characterized in that: The phosphorous acid chelating agent is one of 1-hydroxypropylidene-1,1'-diphosphonic acid, 1-hydroxybutylidene-1,1'-diphosphonic acid, aminotrimethylenephosphonic acid, ethylenediamine (tetramethylenephosphonic acid), and 1-hydroxyethane-1,1'-diphosphonic acid.

6. The method for preparing a metal etching solution according to claim 1, characterized in that: The corrosion inhibitor is one of 4-carboxybenzotriazole, 5-carboxybenzotriazole, 5-methylbenzotriazole, 5-chlorobenzotriazole, isocitric acid, tartaric acid, malic acid, adenine, guanine, guanine nucleoside, cytosine, thymine, uracil, quinalidine acid, bipyridine, o-diazophenanthrene, benzotriazole, and citric acid.

7. The method for preparing a metal etching solution according to claim 1, characterized in that: The inorganic base mentioned is one of ammonia, sodium hydroxide, and potassium hydroxide.

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