Ag etching solution, preparation method and use thereof

Abstract

The application provides an Ag etching solution, a preparation method and application thereof. The Ag etching solution comprises the following components in a weight ratio: 40-80 parts of inorganic acid; 10-50 parts of organic acid; 0.05-1.5 parts of corrosion inhibitor; 0.1-2 parts of chelating agent; 1-7.5 parts of buffer; and 30-50 parts of ultrapure water. The application further discloses a preparation method of the Ag etching solution and application thereof in the field of etching ITO-Ag-ITO composite layers. The inorganic acid is selected from one or more of phosphoric acid, sulfuric acid, carbonic acid, boric acid, hydrobromic acid, iodic acid, hypoiodous acid, hydrofluoric acid and nitric acid. The inorganic acid is preferably phosphoric acid and nitric acid. The Ag etching solution has a stable etching rate for ITO-Ag-ITO, and is not damaged to the insulating layer and photoresist, and can be used in the OLED pixel electrode manufacturing process, and the Ag layer is not provided with burrs and is not shrunk after etching.

Description

TECHNICAL FIELD

[0001] The present application relates to etching liquid technology, in particular to an Ag etching liquid, its preparation method and use. BACKGROUND

[0002] ITO-Ag-ITO etching liquid is mostly used in the etching of pixel electrode in the manufacturing process of TFT-LCD and OLED. The current commercial ITO-Ag-ITO etching method can be divided into three types according to its process steps as follows:

[0003] One-step method: ITO-Ag-ITO etching liquid is used to realize the etching of ITO and Ag stack through one process step. The advantage is simple process and low equipment requirement; the disadvantage is that the etching of the same etching liquid is compatible with two material stacks with huge difference in etching rate, which is easy to cause morphology defects.

[0004] Two-step method: the first step uses ITO-Ag etching liquid to complete the etching of top-ITO and Ag, and the second step uses special ITO etching liquid to complete the etching of bottom-ITO and the morphology modification of top-ITO. The process and equipment requirement are more complex than one-step method, but the step-by-step etching makes the process easier to adjust, and also can obtain better morphology.

[0005] Three-step method: the etching process is divided into three steps, the upper and lower ITO is etched by ITO etching liquid, and the middle layer Ag (a small part of residual ITO) is etched by Ag etching liquid. The etching process of three layers can be adjusted respectively, and more precise morphology control can be achieved.

[0006] Common ITO-Ag-ITO etching liquid is mostly phosphoric acid-nitric acid-acetic acid system, phosphoric acid as the main hydrogen ion source, nitric acid provides oxidation in Ag etching process, and acetic acid as buffer component maintains the ion concentration balance of the whole system. Because Ag itself is very active, the etching rate in oxidizing acid is extremely fast, and morphology defects such as burr and shrinkage are easy to occur in the etching process.

[0007] Some Ag etching liquids are disclosed in the prior art, for example:

[0008] CN114990553A discloses a silver etching liquid composition, relates to the technical field of silver etching liquid. The composition is composed of 40-60% of phosphoric acid, 2-10% of nitric acid, 0.1-10% of organic acid, 0.15% of nitrate, 0.15% of nitrogen-containing organic matter, and the rest is water. The beneficial effects of the present application are: the present application can reduce the problem of a small amount of silver residue or silver re-adsorption deposition in the silver etching process by adding a nitrogen-containing organic compound with a specific structure. The nitrogen-containing organic compound introduced in the present application is a common organic alcohol amine compound on the market, which is conducive to large-scale industrialization.

[0009] CN111910187A discloses a silver etching liquid composition, which comprises inorganic acid, organic acid, inorganic salt and ion water in a residual amount. The silver etching liquid has strong etching ability, long service life, can effectively etch single film composed of silver or silver alloy, or multilayer film composed of the single film and transparent conductive film, and will not cause silver residue or residue, and has good application prospect in the field of semiconductor flat panel display and other microelectronics.

[0010] In the prior art, the Ag etching process is prone to problems such as burr and internal shrinkage. Therefore, it is necessary to develop an Ag etching liquid which has stable etching rate for ITO-Ag-ITO and does not damage the insulating layer and photoresist. SUMMARY

[0011] The purpose of the present application is to solve the problems of burr and internal shrinkage in the Ag etching process. The Ag etching liquid has stable etching rate for ITO-Ag-ITO and does not damage the insulating layer and photoresist, and can be used in the OLED pixel electrode manufacturing process. After Ag layer etching, there is no burr and internal shrinkage.

[0012] It should be noted that in the present application, unless otherwise specified, the specific meaning of "including" involved in the composition limitation and description includes both open "including", "containing" and the like and their similar meanings, and also includes closed "consisting of" and the like and their similar meanings.

[0013] To achieve the above purpose, the technical scheme adopted by the present application is as follows: an Ag etching liquid, comprising the following components in a weight ratio:

[0014]

[0015] Further, the inorganic acid is selected from one or more of phosphoric acid, sulfuric acid, carbonic acid, boric acid, hydrobromic acid, iodic acid, hypoiodous acid, hydrofluoric acid and nitric acid.

[0016] Further, the inorganic acid is preferably phosphoric acid and nitric acid. Phosphoric acid can provide a large amount of hydrogen ions, nitric acid can provide strong oxidizing properties, and the combination of phosphoric acid and nitric acid also has cost and environmental advantages.

[0017] Further, the mass ratio of the phosphoric acid and nitric acid is 9-20:1.

[0018] Further, the mass ratio of the phosphoric acid and nitric acid is preferably 10-15:1.

[0019] Further, the mass ratio of the phosphoric acid and nitric acid is 11:1.

[0020] Further, the inorganic acid is 50-70 parts.

[0021] Further, the organic acid is selected from one or more of acetic acid, citric acid, tartaric acid, oxalic acid, glycolic acid, benzenehexacarboxylic acid, thionaphthene, trichloroacetic acid, and trinitrobenzenesulfonic acid.

[0022] Further, the organic acid is preferably acetic acid.

[0023] Further, the organic acid is 20-30 parts.

[0024] Further, the corrosion inhibitor is selected from one or more of 2-aminobenzothiazole, benzotriazole, 2-mercaptobenzothiazole, methylbenzotriazole, tallow amine, hexadecylamine, and octadecylamine.

[0025] Further, the corrosion inhibitor is preferably 2-aminobenzothiazole and / or benzotriazole. Both 2-aminobenzothiazole and benzotriazole exist simultaneously in physical adsorption and chemical adsorption, i.e., intermolecular forces and lone pair electrons and metal empty orbitals combine to form coordination compounds, and form a dense and ordered protective film on the Ag surface, inhibiting the rapid corrosion of Ag and preventing the formation of burrs and internal shrinkage.

[0026] Further, the mass ratio of the 2-aminobenzothiazole and benzotriazole is 1-10:1.

[0027] Further, the mass ratio of the 2-aminobenzothiazole and benzotriazole is preferably 1-5:1.

[0028] Further, the mass ratio of the 2-aminobenzothiazole and benzotriazole is most preferably 3:1.

[0029] Further, the corrosion inhibitor is 0.1-0.5 parts.

[0030] Further, the chelating agent is selected from one or more of ethylenediaminetetraacetic acid (EDTA), hydrazine nitrobutylamide, diethylenetriamine pentaacetic acid (DTPA), 2,2,2-(1,4,7-triazonane-1,4,7-triyl)triacetic acid (NOTA), 1,4,7,10-tetraazacyclododecane-tetraacetic acid (DOTA).

[0031] Further, the chelating agent is preferably ethylenediaminetetraacetic acid (EDTA).

[0032] Further, the chelating agent is 0.5-1 parts.

[0033] Further, the buffering agent is selected from one or more of sodium aminoacetate, sodium dihydrogen phosphate, sodium glycolate, disodium hydrogen phosphate and sodium phosphate.

[0034] Further, the buffering agent is preferably sodium aminoacetate, sodium dihydrogen phosphate and sodium glycolate. The combination of the three can effectively balance the hydrogen ion concentration in the solution, maintain the etching rate, and the amino nitrogen in the buffering agent, the phosphorus on the phosphate ion and the carboxyl oxygen in the glycolate can all be adsorbed with the lone pair electrons on the outer layer of the metal to synergize with the corrosion inhibitor, further improving the corrosion inhibition effect.

[0035] Further, the buffering agent is preferably sodium aminoacetate, sodium dihydrogen phosphate and sodium glycolate.

[0036] Further, the mass ratio of sodium aminoacetate, sodium dihydrogen phosphate and sodium glycolate is 2:1:1.

[0037] Further, the buffering agent is 3-5 parts.

[0038] Further, the mass ratio of the corrosion inhibitor to the buffering agent is 1:5-20. The buffering agent can maintain the concentration of the reactants during the chemical reaction, and the corrosion inhibitor can be chemically or electrostatically adsorbed with the metal to prevent corrosion. The application discloses the preferred amount ratio of the corrosion inhibitor to the buffering agent. If the amount of the corrosion inhibitor is too much, the etching rate will be too slow. If the amount of the buffering agent is too much or too little, it will affect the stability of the etching rate, and too much salt will affect the electrolyte system of the etching solution, affecting the corrosion inhibition effect of the corrosion inhibitor.

[0039] Further, the mass ratio of the corrosion inhibitor to the buffering agent is preferably 1:5-15.

[0040] Further, the mass ratio of the corrosion inhibitor to the buffering agent is most preferably 1:10.

[0041] Further, the ultrapure water is deionized water with a resistance of ≥18MΩ.

[0042] Further, the ultrapure water is 40-45 parts.

[0043] Further, the pH of the etching solution is <2.

[0044] Further, the pH of the etching solution is preferably <1.

[0045] Another object of the present application also discloses a preparation method of the Ag etching solution, comprising the following steps:

[0046] Step 1: weigh each component respectively;

[0047] Step 2: add all components into a container and heat to 30-40℃ under stirring until all materials are completely dissolved, the solution is transparent or light yellow, and the Ag etching solution is prepared.

[0048] Another object of the present application also discloses the use of the Ag etching solution in the field of etching ITO-Ag-ITO composite layer.

[0049] Another object of the present application also discloses a method for etching ITO-Ag-ITO composite layer by using the Ag etching solution, comprising the following steps:

[0050] S1: removing (completely or partially) the upper ITO of the ITO-Ag-ITO composite layer;

[0051] S2: immersing the substrate plated with the ITO-Ag-ITO composite layer into the Ag etching solution for the second step etching.

[0052] S3: removing the lower ITO of the ITO-Ag-ITO composite layer.

[0053] Further, S1: immersing the substrate plated with the ITO-Ag-ITO composite layer into the oxalic acid etching solution for the first step etching; the etching time is 40-80s and the etching temperature is 40-45℃.

[0054] Further, the oxalic acid etching solution in S1 is 3.4-4.5wt% oxalic acid etching solution.

[0055] Further, the oxalic acid etching solution in S1 is 3.4wt% oxalic acid etching solution.

[0056] Further, the etching time in S1 is 50-70s.

[0057] Further, the etching temperature in S1 is 45℃.

[0058] Further, the etching time in S2 is 50-150s and the etching temperature is 23-28℃.

[0059] Further, the etching time in S2 is 80-110s.

[0060] Further, the etching temperature in S2 is 25 DEG C.

[0061] Further, S3: the substrate plated with the ITO-Ag-ITO composite layer is immersed in oxalic acid etching solution to perform third step etching; the etching time is 40-80s, and the etching temperature is 40-45 DEG C.

[0062] Further, the oxalic acid etching solution in S3 is 3.4-4.5wt% oxalic acid etching solution.

[0063] Further, the oxalic acid etching solution in S3 is 3.4wt% oxalic acid etching solution.

[0064] Further, the etching time in S3 is 50-70s.

[0065] Further, the etching temperature in S3 is 45 DEG C.

[0066] The Ag etching solution, the preparation method and the use thereof have the following advantages compared with the prior art:

[0067] 1) The specific corrosion inhibitor is used in the present application, compared with the Ag acid etching solution without the corrosion inhibitor, the corrosion inhibitor used in the present application can effectively inhibit the too fast corrosion of Ag in the mixed acid, and expand the process window. Especially, the 2-aminobenzothiazole and benzotriazole are used to prepare the corrosion inhibitor system, which can effectively prevent the defects such as edge burr and internal shrinkage caused by the too fast etching rate during the etching process;

[0068] 2) The specific buffer system is used in the present application, compared with the Ag acid etching solution without the buffer system, the buffer agent can stabilize the etching rate and the etching appearance parameters after etching; and the buffer agent used in the present application has chelating performance after ionization, which can further prolong the service life of the etching solution. Especially, the buffer agent sodium aminoacetate, sodium dihydrogen phosphate and sodium glycolate are used to prepare the corrosion inhibitor system, which can effectively balance the hydrogen ion concentration in the solution, maintain the etching rate, and the amino nitrogen in the buffer agent, the phosphorus on the phosphate ion and the carboxyl oxygen in the glycolate can all adsorb the outer pair of electrons of the metal and synergize with the corrosion inhibitor, thereby further improving the corrosion inhibition effect;

[0069] 3) The Ag etching solution has high etching rate for ITO and Ag, and under the use temperature (23-28 DEG C), the etching rate of ITO is 0.5-1.5um / min, and the etching rate of Ag is 0.5-1.5um / min.

[0070] 4) The Ag etching solution adds the chelating agent such as ethylenediaminetetraacetic acid, which can realize high service life, and the Ag dissolution amount is greater than 300ppm.

[0071] Therefore, the Ag etching solution has very good application prospect and large-scale industrialization promotion potential in the field of display panels.​ Attached Figure Description

[0072] Figure 1 Images of the ITO-Ag-ITO stack after etching using the etching solution of Comparative Example 1;

[0073] Figure 2 for Figure 1 A magnified view of a portion of the image;

[0074] Figure 3 Images of the ITO-Ag-ITO stack after etching using the etching solution of Comparative Example 2;

[0075] Figure 4 for Figure 3 A magnified view of a portion of the image;

[0076] Figure 5 Images of the ITO-Ag-ITO stack after etching using the etching solution of Example 1;

[0077] Figure 6 for Figure 5 A magnified view of a portion of the image. Detailed Implementation

[0078] The present invention will be further described below with reference to the embodiments:

[0079] Examples 1-15

[0080] This embodiment discloses a variety of Ag etching solutions, the composition and weight ratio of which are shown in Table 1.

[0081] The preparation method of the Ag etching solution is as follows: weigh each component according to Table 1, add all components to a container, and heat to 35°C with stirring until all materials are completely dissolved and the solution is transparent or light yellow, thus preparing the Ag etching solution.

[0082] Table 1. Components and weight ratios of Ag etching solutions in Examples 1-15

[0083]

[0084]

[0085]

[0086] Comparative Examples 1-5

[0087] Comparative Examples 1-5 disclose various etching solutions, the components and weight ratios of which are shown in Table 2, and their preparation methods are the same as those in Example 1.

[0088] Table 2. Components and weight ratios of etching solutions for Comparative Examples 1-5

[0089]

[0090]

[0091] Performance Testing and Explanation

[0092] The performance of each of the above embodiments or comparative examples was tested below. The test results are shown in Table 3. Compared with comparative examples 1-5, embodiments 1-15 used a compound of inorganic acid, organic acid, corrosion inhibitor, buffer, and chelating agent. After etching, there were no morphological defects such as burrs or shrinkage. The etching rates of Ag and ITO were appropriate, and there was no problem of the etching rate of a certain material being too fast or too slow. It was also beneficial to improve the Ag lifetime. However, the etching solution of comparative examples 1-5 lacked a certain component, which led to a decrease in the performance of the etching solution.

[0093] Table 3 Test Results

[0094]

[0095] Figure 1 Images of the ITO-Ag-ITO stack after etching using the etching solution of Comparative Example 1; Figure 2 for Figure 1 The enlarged view shows that the etching solution in Comparative Example 1 has a poor etching inhibition effect, and the Ag etching rate is too fast, so the middle Ag layer shrinks significantly after etching.

[0096] Figure 3 Images of the ITO-Ag-ITO stack after etching using the etching solution of Comparative Example 2; Figure 4 for Figure 3 The enlarged view shows that the etching rate of the ITO etching solution in Comparative Example 2 was too high, resulting in a large exposed area of ​​Ag surface with pitting holes. Therefore, after etching, there are a lot of burrs on the edge of Ag.

[0097] Figure 5 Images of the ITO-Ag-ITO stack after etching using the etching solution of Example 1; Figure 6 for Figure 5 The enlarged view shows that, compared with Comparative Example 1 and Comparative Example 2, Example 1 has no morphological defects such as burrs or ITO shrinkage, and very little ITO remains in the etched channels.

[0098] in:

[0099] The test method for the cleaning effect after etching is as follows:

[0100] The ITO-Ag-ITO samples were etched using the etching solutions from the above embodiments and comparative examples of the present invention, and then cleaned. The specific steps are as follows:

[0101] Step 1: immerse the substrate plated with ITO-Ag-ITO composite layer in the 3.4wt% oxalic acid etching solution for first-step etching; the etching time is 60s and the etching temperature is 45℃.

[0102] Step 2: immerse the substrate plated with ITO-Ag-ITO composite layer in the etching solution for second-step etching; the etching time is 90s and the etching temperature is 25℃.

[0103] Step 3: immerse the substrate plated with ITO-Ag-ITO composite layer in the 3.4wt% oxalic acid etching solution for third-step etching; the etching time is 60s and the etching temperature is 45℃.

[0104] Step 4: rinse the ITO-Ag-ITO sample piece in ultrapure water for at least twice and dry it with nitrogen.

[0105] Step 5: observe the sample piece morphology under SEM.

[0106] The ultrapure water used in the steps is deionized water with a resistance of at least 18MΩ.

[0107] The test method for performance 2 etching rate is as follows:

[0108] The Ag etching solution of Examples 1-15 and Comparative Examples 1-5 is used to etch ITO and Ag sample pieces, and after etching, the sample pieces are cleaned, and the specific steps are as follows:

[0109] Step 1: configure the etching solution according to the proportion of the examples and comparative examples, heat it to 25℃ in a water bath, immerse the sample piece in the etching solution and shake it, and the surface metal of the sample piece is completely etched in 10s as a gradient;

[0110] Step 2: rinse the sample piece in ultrapure water for at least twice and dry it with nitrogen.

[0111] Step 3: measure the thickness of the sample piece under SEM to calculate the etching rate.

[0112] The test method for performance 3 Ag dissolution life is as follows:

[0113] The etching solution of Examples 1-15 and Comparative Examples 1-5 of the present application is added with Ag powder from 0 to 500ppm at a gradient of 50ppm to dissolve the Ag powder, and the ITO-Ag-ITO sample piece is etched, and after etching, the sample piece is cleaned, and the specific steps are as follows:

[0114] Step 1: immerse the substrate plated with ITO-Ag-ITO composite layer in the 3.4wt% oxalic acid etching solution for first-step etching; the etching time is 60s and the etching temperature is 45℃.

[0115] Step 2: Substrate coated with ITO-Ag-ITO composite layer was immersed in the etching solution of the examples and comparative examples for the second etching; etching time was 90 s, etching temperature was 25℃.

[0116] Step 3: Substrate coated with ITO-Ag-ITO composite layer was immersed in 3.4wt% oxalic acid etching solution for the third etching; etching time was 60 s, etching temperature was 45℃.

[0117] Step 4: The ITO-Ag-ITO sample was washed in ultrapure water for at least twice, and dried by nitrogen.

[0118] Step 5: The sample morphology was observed under SEM, and the Ag dissolving amount corresponding to the morphology failure was the limit of etching solution life.

[0119] Finally, it should be noted that: the above examples are used to illustrate the technical solutions of the present application, but not limited to; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An Ag etching solution, characterized in that, The components include the following weight proportions: 40-80 parts of inorganic acid; 10-50 parts organic acids; Corrosion inhibitor 0.05-1.5 parts; Chelating agent 0.1-2 parts; 1-7.5 parts buffer; 30-50 parts ultrapure water; The inorganic acid includes phosphoric acid; The buffer is sodium glycine, sodium dihydrogen phosphate, and sodium glycolate; The inorganic acids, in addition to phosphoric acid, also include one or more of the following: sulfuric acid, carbonic acid, boric acid, hydrobromic acid, iodic acid, hypoiodic acid, hydrofluoric acid, and nitric acid. The organic acid is selected from one or more of acetic acid, citric acid, tartaric acid, oxalic acid, glycolic acid, benzoic acid, thiocarboxylic acid, trichloroacetic acid, and trinitrobenzenesulfonic acid; The corrosion inhibitors are 2-aminobenzothiazole and benzotriazole; The chelating agent is selected from one or more of ethylenediaminetetraacetic acid, hydrazine nitramide, diethyltriaminepentaacetic acid, 2,2,2-(1,4,7-triazacyclononane-1,4,7-triyl)triacetic acid and 1,4,7,10-tetraazacyclododecane-tetraacetic acid.

2. The Ag etching solution according to claim 1, characterized in that, The mass ratio of the corrosion inhibitor to the buffer is 1:5-20.

3. The Ag etching solution according to claim 1, characterized in that, The pH of the etching solution is <2.

4. A method for preparing the Ag etching solution according to any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Weigh each component separately; Step 2: Add all components to a container and heat to 30-40℃ while stirring until all materials are completely dissolved and the solution is transparent or pale yellow, thus preparing the Ag etching solution.

5. The use of the Ag etching solution according to any one of claims 1-3 in the field of etching ITO-Ag-ITO composite layers.

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