Preparation method of metal etching liquid

Abstract

The invention discloses a preparation method of metal etching liquid, and belongs to the technical field of semiconductor element processing. An oxidizing agent, oxalate, aminocarboxylic acid, a phosphorous acid chelating agent, polyoxypropylene polyoxyethylene ether, an anticorrosive agent, a stabilizer, inorganic alkali and water are stirred and mixed uniformly to obtain the metal etching liquid. The preparation method comprises the following steps: reacting mercaptobenzothiazole, copper nitrate and DMF (Dimethyl Formamide) at 30-40 DEG C; adding maleic acid triethanolamine diester, octavinyl octasilsesquioxane and triethanolamine, reacting at the temperature of 60-70 DEG C, and removing DMF (Dimethyl Formamide) through reduced pressure distillation to obtain the product, the mercaptobenzothiazole is realized by forming a layer of protective film on the metal surface, so that the metal is prevented from being further corroded; the silsesquioxane is added, and due to the special chemical structure of the silsesquioxane, a specific antibacterial layer can be formed on the metal surface, and the antibacterial performance of the etching solution is further enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor element processing, in particular to a method for preparing a metal etching solution. Background Art

[0002] Metal etching is the process of processing the shiny metal surface into a rough and concave surface by chemical or mechanical treatment. In recent decades, with the economic development and social progress, the application of metal etching technology has been paid more and more attention. As a precise and scientific chemical processing technology, chemical etching is widely used on a variety of metal materials. The process of metal etching in etching solution is first of all the dissolution of grains on the surface of metal parts; secondly, dissolution also occurs on the grain boundaries. Generally speaking, the grain boundaries and grains are dissolved at different dissolution rates.

[0003] Chinese patent CN113667979A: discloses a copper-molybdenum metal etching solution and its application. The copper-molybdenum metal etching solution comprises, by weight percentage, 1 to 21 wt% of hydrogen peroxide, 0.01 to 10 wt% of a shape control agent, 0.01 to 5 wt% of an etching stabilizer, 1 to 13 wt% of a chelating agent, 0.01 to 8 wt% of a pH regulator, and 0.01 to 2.39 wt% of an etching additive, and the remainder 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 liquid composition and its use method. It includes: component A and component B, which is added by 0.05-0.3% of the weight of component A every time the copper ion increases by 100ppm.

[0005] Chinese patent CN114438495A: Provides a metal etching solution, comprising: 5 to 30wt% oxidant; 2.5 to 15wt% amino acid; 2.5 to 15wt% phosphate; 2 to 15wt% non-amino acid carboxylic acid; and the balance of water. In the present invention, hydrogen peroxide and persulfate are selected as oxidants, and the weight ratio between the two is controlled to be between 1:1.5 and 1:5.

[0006] The etching solutions prepared by the above patents and prior art have disadvantages such as too large underCut and poor antibacterial performance. Summary of the invention

[0007] In order to solve the above problems, the present invention provides a method for preparing a metal etching solution, and the operating steps are as follows:

[0008] S1: Mix 1-5 parts of oxidant and 20-30 parts of water, stirring and mixing evenly;

[0009] S2: Add 1-5 parts of oxalate, 5-10 parts of aminocarboxylic acid, and 50-70 parts of water, and stir to mix evenly;

[0010] 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 anticorrosive agent, 0.002-0.05 parts of stabilizer, and 0.2-2.5 parts of inorganic base, stir and mix evenly to obtain metal etching solution.

[0011] As a preferred embodiment, the oxidant is persulfate or hydrogen peroxide.

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

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

[0014] As a preferred embodiment, the phosphorous acid chelating agent is one of 1-hydroxypropylene-1,1'-diphosphoric acid, 1-hydroxybutylene-1,1'-diphosphoric acid, aminotrimethylenephosphonic acid, ethylenediamine (tetramethylenephosphonic acid), and 1-hydroxyethane-1,1'-diphosphoric acid.

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

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

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

[0018] A1: Mix 5-10 parts of mercaptobenzothiazole, 4-7 parts of copper nitrate and 100-130 parts of DMF by weight, and react at 30-40° C. for 60-100 minutes;

[0019] A2: Add 2-5 parts of triethanolamine maleate, 5-10 parts of octavinyl octasilsesquioxane and 3-6 parts of triethanolamine, react at 60-70°C for 100-130 minutes, remove DMF by reduced pressure distillation, and vacuum dry to obtain a stabilizer.

[0020] As a preferred embodiment, the preparation method of triethanolamine maleate is as follows:

[0021] 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, and the mixture is reacted at 60° C.-70° C. for 100-130 minutes.

[0022] Reaction mechanism

[0023] The reaction mechanism of the stabilizer is:

[0024] The mercaptobenzothiazole / copper complex and triethanolamine maleate undergo an addition reaction; the mercaptobenzothiazole / copper complex and octavinyl octasilsesquioxane undergo an addition reaction; and 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 reactions with other compounds such as triethanolamine maleate to form more stable compounds.

[0027] Corrosion inhibition: Mercaptobenzothiazole is a known highly effective corrosion inhibitor, especially for copper. Its corrosion inhibition effect is mainly achieved by forming a protective film on the metal surface to prevent further corrosion of the metal.

[0028] 2. About the role of silsesquioxane

[0029] Providing stability: Octavinyl octasilsesquioxane undergoes an addition reaction with the benzothiazole copper complex through its polyvinyl groups to form a network structure, which helps to increase the overall stability of the metal etching solution.

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

[0031] Technical Effects

[0032] The present invention discloses a method for preparing a metal etching solution. Compared with the prior art, the present invention has the following significant effects:

[0033] 1. The stabilizer prepared by the present invention can effectively improve the accuracy and uniformity of metal etching. Using this stabilized metal etching solution, the etching process can be more accurately controlled to obtain a more uniform etching effect, which is particularly important for the electronics industry;

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

[0035] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description in combination with embodiments and comparative examples:

[0036] 1. Etching speed test: A Cu plate with a length of 1 cm, a width of 1 cm, and a thickness of 1 mm was placed in the etching solution prepared by the present invention and immersed in it for 10 minutes at room temperature for etching; the Cu ion concentration obtained by the etching process was measured using an atomic absorption photometer, and the dissolution amount per unit area was calculated to obtain the dissolution rate, which is the etching rate;

[0037] 2. Bite length test:

[0038] A Ti layer with a thickness of 300 nm is first deposited on a 4 cm Si substrate with a thermal oxide film (SiO2) with a thickness of 10 nm by sputtering, and then a Cu layer with a thickness of 300 nm is deposited on the Ti / SiO2 / Si substrate, and a positive photoresistor resin coating (with a thickness of 40 μm) is covered on the Cu / Ti / SiO2 / Si substrate to form a model by photolithography; thereafter, a Cu layer (with a thickness of 20 μm) is deposited by electroplating, and then a Ni layer (with a thickness of 5 μm) and a Sn / Ag (97:3) layer (with a thickness of 15 μm) are successively covered; finally, the photoresistor resin coating is removed to obtain a semiconductor substrate for evaluation;

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

[0040] 2. Antibacterial rate detection: refer to WS / T650-2019 "Antibacterial and antibacterial effect evaluation method" for testing.

[0041] Example 1

[0042] A method for preparing a metal etching solution, the operating steps of which are:

[0043] S1: Mix 1g oxidant and 20g water, stirring evenly;

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

[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 anticorrosive agent, 0.002 g of stabilizer, and 0.2 g of inorganic base, stir and mix evenly to obtain a metal etching solution.

[0046] The oxidant is persulfate.

[0047] The oxalate is ammonium oxalate.

[0048] The aminocarboxylic acid is alanine.

[0049] The phosphorous acid chelating agent is 1-hydroxypropylene-1,1'-diphosphoric acid.

[0050] The anticorrosive agent is 4-carboxybenzotriazole.

[0051] The inorganic base is ammonia.

[0052] The preparation method of the stabilizer is:

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

[0054] A2: Add 2 g of triethanolamine maleate, 5 x 10-3 g of octavinyl octasilsesquioxane and 3 g of triethanolamine, react at 60°C for 100 minutes, remove DMF by reduced pressure distillation, and vacuum dry to obtain a stabilizer.

[0055] The preparation method of the described triethanolamine maleate is:

[0056] 14 g of maleic anhydride and 31 g of triethanolamine were mixed and added to a reactor, and 1 g of acetic acid was added to the reactor, and the mixture was reacted at 60° C. for 100 minutes to obtain triethanolamine maleate.

[0057] Example 2

[0058] A method for preparing a metal etching solution, the operating steps of which are:

[0059] S1: Mix 2g oxidant and 23g water, stirring evenly;

[0060] S2: Add 2g oxalate, 6g aminocarboxylic acid, and 55g water, and stir to mix well;

[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 anticorrosive agent, 0.02 g of stabilizer, and 1 g of inorganic base, stir and mix well to obtain a metal etching solution.

[0062] The oxidant is persulfate.

[0063] The oxalate is sodium oxalate.

[0064] The aminocarboxylic acid is valine.

[0065] The phosphorous acid chelating agent is 1-hydroxybutylene-1,1'-diphosphoric acid.

[0066] The anticorrosive agent is 5-carboxybenzotriazole.

[0067] The inorganic base is sodium hydroxide.

[0068] The preparation method of the stabilizer is:

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

[0070] A2: Add 3g of triethanolamine maleate, 6x10-3g of octavinyl octasilsesquioxane and 4g of triethanolamine, react at 65°C for 110 minutes, remove DMF by reduced pressure distillation, and vacuum dry to obtain a stabilizer.

[0071] The preparation method of the described triethanolamine maleate is:

[0072] 16 g of maleic anhydride and 38 g of triethanolamine were mixed and added to a reactor, and 2 g of acetic acid was added to the reactor. The mixture was reacted at 65° C. for 110 minutes to obtain triethanolamine maleate.

[0073] Example 3

[0074] A method for preparing a metal etching solution, the operating steps of which are:

[0075] S1: Stir 4g of oxidant and 28g of water until evenly mixed;

[0076] S2: Add 4g oxalate, 8g aminocarboxylic acid and 65g water, and stir to mix well;

[0077] S3: Continue to add 1.3 g of phosphorous acid chelating agent, 0.4 g of surfactant polyoxypropylene polyoxyethylene ether, 0.8 g of anticorrosive agent, 0.04 g of stabilizer, and 2 g of inorganic base, stir and mix evenly to obtain a metal etching solution.

[0078] The oxidant is hydrogen peroxide.

[0079] The oxalate is sodium oxalate.

[0080] The aminocarboxylic acid is isoleucine.

[0081] The phosphorous acid chelating agent is aminotrimethylenephosphonic acid.

[0082] The anticorrosive agent is 5-methylbenzotriazole.

[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 were mixed and reacted at 35°C for 90 minutes;

[0086] A2: Add 4 g of triethanolamine maleate, 8 x 10-3 g of octavinyl octasilsesquioxane and 5 g of triethanolamine, react at 65°C for 120 minutes, remove DMF by reduced pressure distillation, and vacuum dry to obtain a stabilizer.

[0087] The preparation method of the described triethanolamine maleate is:

[0088] 20 g of maleic anhydride and 48 g of triethanolamine were mixed and added to a reactor, and 3 g of acetic acid was added to the reactor. The mixture was reacted at 65° C. for 120 minutes to obtain triethanolamine maleate.

[0089] Example 4

[0090] A method for preparing a metal etching solution, the operating steps of which are:

[0091] S1: Stir 5g of oxidant and 30g of water until evenly mixed;

[0092] S2: Add 5g oxalate, 10g aminocarboxylic acid, and 70g water, and stir to mix evenly;

[0093] S3: Continue to add 1.5 g of phosphorous acid chelating agent, 0.5 g of surfactant polyoxypropylene polyoxyethylene ether, 1 g of anticorrosive agent, 0.05 g of stabilizer, and 2.5 g of inorganic base, stir and mix evenly to obtain a metal etching solution.

[0094] The oxidant is hydrogen peroxide.

[0095] The oxalate is potassium oxalate.

[0096] The aminocarboxylic acid is glycine.

[0097] The phosphorous acid chelating agent is ethylenediamine (tetramethylenephosphonic 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 and 130 g of DMF were mixed and reacted at 40°C for 100 minutes;

[0102] A2: Add 5 g of triethanolamine maleate, 10x10-3 g of octavinyl octasilsesquioxane and 6 g of triethanolamine, react at 70°C for 130 minutes, remove DMF by reduced pressure distillation, and vacuum dry to obtain a stabilizer.

[0103] The preparation method of the described triethanolamine maleate is:

[0104] 22 g of maleic anhydride and 53 g of triethanolamine were mixed and added to a reactor, and 4 g of acetic acid was added to the reactor. The mixture was reacted at 70° C. for 130 minutes to obtain triethanolamine maleate.

[0105] Comparative Example 1

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

[0107] Comparative Example 2

[0108] Without adding triethanolamine maleate, the other steps were the same as in Example 1.

[0109] Comparative Example 3

[0110] Octavinyloctasilsesquioxane was not 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] Etching speed / mm / min Biting edge length / μm Antibacterial rate / % Example 1 205 0.21 99.93 Example 2 196 0.19 99.95 Example 3 188 0.17 99.98 Example 4 173 0.16 99.99 Comparative Example 1 255 0.48 85.36 Comparative Example 2 226 0.30 94.91 Comparative Example 3 221 0.27 96.13

[0114] Through the data analysis of the above embodiments and comparative examples, the stabilizer prepared by the present invention can effectively improve the antibacterial rate of the etching solution and reduce the undercut length.

[0115] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a metal etching solution, the operating steps of which are: S1: Mix 1-5 parts of oxidant and 20-30 parts of water, stirring and mixing evenly; S2: Add 1-5 parts of oxalate, 5-10 parts of aminocarboxylic acid, and 50-70 parts of 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 anticorrosive agent, 0.002-0.05 parts of stabilizer, and 0.2-2.5 parts of inorganic base, stir and mix evenly to obtain metal etching solution; The stabilizer is prepared by reacting mercaptobenzothiazole / copper complex with triethanolamine maleate and octavinyl octasilsesquioxane.

2. A 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, wherein: The oxalate is one of ammonium oxalate, sodium oxalate and potassium oxalate.

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

5. The method for preparing a metal etching solution according to claim 1, wherein: The phosphorous acid chelating agent is one of 1-hydroxypropylene-1,1'-diphosphoric acid, 1-hydroxybutylene-1,1'-diphosphoric acid, aminotrimethylenephosphonic acid, ethylenediamine (tetramethylenephosphonic acid), and 1-hydroxyethane-1,1'-diphosphoric acid.

6. The method for preparing a metal etching solution according to claim 1, wherein: The anticorrosive agent is one of 4-carboxybenzotriazole, 5-carboxybenzotriazole, 5-methylbenzotriazole, 5-chlorobenzotriazole, isocitric acid, tartaric acid, malic acid, adenine, guanine, guanosine, cytosine, thymine, uracil, quinaldic acid, bipyridine, o-phenanthroline, benzotriazole and citric acid.

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

8. The method for preparing a metal etching solution according to claim 1, wherein: The preparation method of the stabilizer is: A1: Mix 5-10 parts of mercaptobenzothiazole, 4-7 parts of copper nitrate and 100-130 parts of DMF by weight, and react at 30-40° C. for 60-100 minutes; A2: Add 2-5 parts of triethanolamine maleate, 5-10 parts of octavinyl octasilsesquioxane and 3-6 parts of triethanolamine, react at 60-70°C for 100-130 minutes, remove DMF by reduced pressure distillation, and vacuum dry to obtain a stabilizer.

9. The method for preparing a metal etching solution according to claim 8, wherein: The preparation method of the described triethanolamine maleate is: 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, and the mixture is reacted at 60° C.-70° C. for 100-130 minutes to obtain triethanolamine maleate.