ITO (Indium Tin Oxide) etching solution, preparation method and use method

Abstract

The invention discloses an ITO (Indium Tin Oxide) etching solution as well as a preparation method and a use method thereof, and the ITO etching solution comprises the following components in percentage by mass: 1.0 wt%-5.00 wt% of boric acid, 5.0 wt%-20 wt% of silicic acid, 20 wt%-30 wt% of 1-hydroxyethylidene-1, 1-diphosphonic acid, 0.1 wt%-0.5 wt% of a corrosion inhibitor and the balance of water. The ITO etching solution provided by the invention is relatively stable in ITO etching rate, and has no corrosion to copper or no side etching phenomenon of copper.

Description

Technical Field

[0001] The invention relates to the technical field of etching, and in particular to an ITO etching solution, a preparation method and a use method thereof. Background Art

[0002] ITO (Indium Tin Oxide) is a transparent conductive material. ITO conductive film has low resistivity, high visible light transmittance, high infrared reflection, excellent adhesion to the substrate, anti-scratch properties and other properties and is widely used in the panel display industry.

[0003] Many gate layers in the panel industry are Cu+ITO (high temperature) structures, which combine the excellent conductivity of copper (Cu) and the transparent conductivity of indium tin oxide (ITO), which is beneficial to improving the performance of display panels. The circuit manufacturing method of this structure is usually a two-step etching method, that is, etching copper first and then etching ITO. Therefore, there are some problems, such as the copper cannot be well protected during the etching of ITO, which is highly corrosive to copper, causing side etching of copper and forming defects.

[0004] In order to reduce the corrosion of copper during the ITO etching process, the present invention is specially proposed. Summary of the invention

[0005] The object of the present invention is to provide an ITO etching solution, a preparation method and a use method, which can reduce the corrosion of copper and the defects caused by the side etching of copper during the ITO etching process.

[0006] The present invention is achieved in that:

[0007] In a first aspect, the present invention provides an ITO etching solution, which comprises, by mass percentage, 1.0wt% to 5.00wt% of boric acid, 5.0wt% to 20wt% of silicic acid, 20wt% to 30wt% of hydroxyethylidene diphosphonic acid, 0.1wt% to 0.5wt% of a corrosion inhibitor and the remainder of water.

[0008] The ITO etching solution provided by the present invention uses hydroxyethylidene diphosphonic acid as a main component, and uses boric acid and silicic acid as auxiliary oxidants, has low corrosion ability, mild etching conditions, a relatively wide etching time, and is easier to control CD Loss (Critical Dimension Loss).

[0009] The ITO etching solution provided by the present invention has a relatively stable ITO etching rate because boric acid, silicic acid and hydroxyethylidene diphosphonic acid can gradually ionize hydrogen ions. At the same time, hydroxyethylidene diphosphonic acid can complex with copper ions to protect copper, thereby reducing the corrosion of the ITO etching solution on copper and reducing defects caused by side etching of copper.

[0010] In an optional embodiment, the corrosion inhibitor is selected from nitrogen azole compounds.

[0011] Nitrogen azole compounds can be physically adsorbed with copper, thereby protecting copper and reducing the corrosion of copper by ITO etching solution.

[0012] In an optional embodiment, the corrosion inhibitor is selected from at least one of pentamethyltetrazolyl and pentaaminotetrazolyl.

[0013] Pentamethyltetrazolyl and pentaaminotetrazolyl have stronger protective ability for copper and are more conducive to reducing the corrosion of copper, thereby reducing the defects caused by side etching of copper.

[0014] In an optional embodiment, the ITO etching solution also includes a chloride salt.

[0015] The introduction of chloride salts into the ITO etching solution is beneficial to accelerate the etching of ITO and can reduce surface residues.

[0016] In an optional embodiment, the mass fraction of the chloride salt is 5 wt% to 10 wt%.

[0017] When the mass fraction of chloride salt is within this range, the ability to remove residues is better.

[0018] In an optional embodiment, the chloride salt is selected from at least one of ammonium chloride, sodium chloride and potassium chloride.

[0019] Chloride salts include ammonium chloride, sodium chloride and potassium chloride, which have better ability to remove residues.

[0020] In an optional embodiment, the ITO etching solution includes 3.00wt% to 5.00wt% of boric acid, 10wt% to 20.00wt% of silicic acid, 25wt% to 30.00wt% of hydroxyethylidene diphosphonic acid, 0.3wt% to 0.5wt% of corrosion inhibitor, 7.5wt% to 10.00wt% of chloride salt and the balance of water.

[0021] Optimizing the ratio of ITO etching solution is beneficial to reducing the corrosion of copper by the etching solution, reducing defects caused by side etching of copper, reducing surface residues, and improving the stability of the etching solution.

[0022] In an optional embodiment, the ITO etching solution includes, by mass percentage, 3.00 wt % boric acid, 10 wt % silicic acid, 25 wt % hydroxyethylidene diphosphonic acid, 0.3 wt % corrosion inhibitor, 7.5 wt % chloride salt and the balance water.

[0023] Further optimization of the ratio of the ITO etching solution is beneficial to further reduce the corrosion of the etching solution to copper, reduce the defects caused by the side etching of copper, reduce the surface residues, and improve the stability of the etching solution.

[0024] In a second aspect, the present invention provides a method for preparing the ITO etching solution described in any one of the aforementioned embodiments, comprising: mixing the components in proportion.

[0025] In an optional embodiment, the method comprises: mixing water, silicic acid and hydroxyethylidene diphosphonic acid to obtain a mixture, and mixing the mixture with the remaining components to obtain the ITO etching solution. The step-by-step mixing is beneficial to improving the mixing efficiency.

[0026] In a third aspect, the present invention provides a method for using the ITO etching solution described in any one of the aforementioned embodiments, comprising: contacting a Cu / ITO film to be etched with the ITO etching solution to etch the Cu / ITO film to be etched.

[0027] In an optional embodiment, the etching temperature is 35°C to 45°C.

[0028] The appropriate etching temperature is helpful to adjust the etching rate, which in turn helps to control the CD Loss within an appropriate range.

[0029] In an optional embodiment, after etching is completed, the surface of the Cu / ITO film to be etched is cleaned with deionized water and dried.

[0030] After etching is completed, the surface of the Cu / ITO film to be etched is cleaned with deionized water within 2 seconds to end the etching reaction and prevent the etching solution from continuing to etch ITO.

[0031] The present invention has the following beneficial effects:

[0032] The ITO etching solution provided by the present invention has a relatively stable ITO etching rate and does not corrode copper or cause side etching of copper. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 This is a SEM cross-sectional view of the ITO after etching in Example 1, the purpose of which is to observe the profile of the metal after etching, CD loss ≤ 0.4 μm.

[0035] Figure 2 This is a SEM cross-sectional view of the ITO layer after etching in Comparative Example 1, the purpose of which is to observe the profile of the metal after etching, CD loss>0.4μm.

[0036] Figure 3 This is a SEM surface image of the ITO layer after etching in Example 1. Its purpose is to observe the residual ITO after etching. No ITO residue occurs.

[0037] Figure 4 This is the SEM surface image of the ITO layer after etching corresponding to Comparative Example 2. Its purpose is to observe the residual ITO after etching. It can be seen that obvious ITO residue occurs. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0039] The embodiment of the present invention provides an ITO etching solution, which comprises, by mass percentage, 1.0wt% to 5.00wt% of boric acid, 5.0wt% to 20wt% of silicic acid, 20wt% to 30wt% of hydroxyethylidene diphosphonic acid, 0.1wt% to 0.5wt% of corrosion inhibitor and the balance of water.

[0040] The ITO etching solution provided by the present invention uses hydroxyethylidene diphosphonic acid as a main component, and uses boric acid and silicic acid as auxiliary oxidants, has low corrosion ability, mild etching conditions, a relatively wide etching time, and is easier to control CD Loss (Critical Dimension Loss).

[0041] The ITO etching solution provided by the present invention has a relatively stable ITO etching rate, can reduce the corrosion of copper, and reduce defects caused by side etching of copper.

[0042] In some embodiments, the mass fraction of boric acid in the ITO etching solution is 1.0wt%, 2.0wt%, 3.0wt%, 4.0wt%, 5.00wt% or any value between 1.0wt% and 5.00wt%. If the mass fraction of boric acid is too high, the side etch CD loss will be too high, and if the mass fraction of boric acid is too low, the residue will increase.

[0043] In some embodiments, the mass fraction of silicate in the ITO etching solution is 5.0wt%, 6.0wt%, 7.0wt%, 8.0wt%, 9.0wt%, 10.0wt%, 11.0wt%, 12.0wt%, 13.0wt%, 14.0wt%, 15.0wt%, 16.0wt%, 17.0wt%, 18.0wt%, 19.0wt%, 20wt% or any value between 5.0wt% and 20wt%. If the mass fraction of silicate is too high, the side erosion CD loss will be too high, and if the mass fraction of silicate is too low, the residue will increase.

[0044] In some embodiments, the mass fraction of hydroxyethylidene diphosphonic acid in the ITO etching solution is 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, 30wt% or any value between 20wt% and 30wt%. If the mass fraction of hydroxyethylidene diphosphonic acid is too high, the side erosion CD loss will be too high, and if the mass fraction of hydroxyethylidene diphosphonic acid is too low, the residue will increase.

[0045] In some embodiments, the mass fraction of the corrosion inhibitor in the ITO etching solution is 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt% or any value between 0.1wt% and 0.5wt%. If the mass fraction of the corrosion inhibitor is too high, the stability of the etching solution will be reduced, thereby reducing the life of the etching solution. If the mass fraction of the corrosion inhibitor is too low, the corrosion of the etching solution to copper will increase, which will cause the copper damage to increase. The corrosion inhibitor is selected from nitrogen azole compounds, and specifically can be selected from at least one of pentamethyltetrazole and pentaaminotetrazole. Pentamethyltetrazole and pentaaminotetrazole have stronger protection ability for copper, which is more conducive to reducing the corrosion of copper, thereby reducing the defects caused by the side engraving of copper.

[0046] In some embodiments, the ITO etching solution also includes a chloride salt, and the mass fraction of the chloride salt is 5wt% to 10wt%, specifically 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt% or any value between 5wt% and 10wt%. If the mass fraction of the chloride salt is too high, it will cause the side erosion CD loss to be too high, and if the mass fraction of the chloride salt is too low, it will cause the residue to increase. The chloride salt can be selected from at least one of ammonium chloride, sodium chloride and potassium chloride. The chloride salt selects ammonium chloride, sodium chloride and potassium chloride chloride salts, which have better ability to remove residues.

[0047] In some embodiments, the ITO etching solution includes 3.00wt% to 5.00wt% of boric acid, 10wt% to 20.00wt% of silicic acid, 25wt% to 30.00wt% of hydroxyethylidene diphosphonic acid, 0.3wt% to 0.5wt% of corrosion inhibitor, 7.5wt% to 10.00wt% of chloride salt and the balance of water.

[0048] Optimizing the ratio of ITO etching solution is beneficial to reducing the corrosion of copper by the etching solution, reducing defects caused by side etching of copper, reducing surface residues, and improving the stability of the etching solution.

[0049] In some embodiments, the ITO etching solution includes, by mass percentage, 3.00 wt % boric acid, 10 wt % silicic acid, 25 wt % hydroxyethylidene diphosphonic acid, 0.3 wt % corrosion inhibitor, 7.5 wt % chloride salt and the balance water.

[0050] The ratio of the ITO etching solution meets the above requirements, which is beneficial to further reduce the corrosion of the etching solution to copper, reduce the defects caused by the side etching of copper, reduce the surface residues, and improve the stability of the etching solution.

[0051] An embodiment of the present invention also provides a method for preparing the ITO etching solution described in any one of the aforementioned embodiments, comprising: first mixing water, silicic acid and hydroxyethylidene diphosphonic acid in proportion to obtain a mixture, and then mixing the mixture with the remaining components to obtain the ITO etching solution, and the remaining components may include boric acid, corrosion inhibitor or boric acid, corrosion inhibitor and chloride salt.

[0052] The components in the ITO etching solution are mixed step by step, which is beneficial to improving the mixing efficiency.

[0053] An embodiment of the present invention also provides a method for using the ITO etching solution described in any one of the aforementioned embodiments, comprising: contacting a Cu / ITO film to be etched with the ITO etching solution to etch the Cu / ITO film to be etched, the etching temperature being 35°C to 45°C, and after etching is completed, using deionized water to clean and dry the surface of the Cu / ITO film to be etched.

[0054] The appropriate etching temperature is conducive to adjusting the etching rate, and thus to controlling the CD Loss within a suitable range. At the same time, after the etching is completed, the surface of the Cu / ITO film to be etched is cleaned with deionized water within 2 seconds to end the etching reaction and prevent the etching solution from continuing to etch ITO.

[0055] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0056] Example 1

[0057] This embodiment provides an ITO etching solution (10 kg), which, by mass percentage, comprises:

[0058] Boric acid 5.00wt%;

[0059] Silicic acid 20wt%;

[0060] 30wt% of hydroxyethylidene diphosphonic acid;

[0061] Corrosion inhibitor 0.5wt%;

[0062] Chloride salt 10wt%;

[0063] The balance is water.

[0064] The ITO etching solution is prepared as follows:

[0065] Weigh water, silicic acid, hydroxyethylidene diphosphonic acid, boric acid, corrosion inhibitor and chloride salt respectively according to the above proportions;

[0066] First, water, silicic acid, and hydroxyethylidene diphosphonic acid are mixed for the first time to obtain a mixture, and then the mixture is mixed with boric acid, a corrosion inhibitor, and a chloride salt for a second time, and stirred (60 minutes) to obtain an ITO etching solution.

[0067] Examples 2-13 and Comparative Examples 1-18

[0068] The only difference between Examples 2-13 and Comparative Examples 1-18 and Example 1 is that the selection or dosage of each component is different. The specific ingredients and dosages of Examples 2-13 and Comparative Examples 1-18 are shown in Table 1, wherein the balance is water.

[0069] Table 1

[0070]

[0071]

[0072] The total mass of the ITO etching solution corresponding to each embodiment and comparative example is 10 kg.

[0073] Comparative Example 19

[0074] The difference between this comparative example and Example 1 is that the corrosion inhibitor is 1,2,3-triazole, and the content is 0.50%. Specifically, the ITO etching solution of Comparative Example 19 includes:

[0075] Boric acid 5.00wt%;

[0076] Silicic acid 20wt%;

[0077] 30wt% of hydroxyethylidene diphosphonic acid;

[0078] 1,2,3-triazole 0.5wt%;

[0079] Sodium chloride 10wt%;

[0080] The balance is water.

[0081] Experimental example

[0082] This experimental example tests the effects of the ITO etching solutions prepared in the embodiments and comparative examples, and the specific test methods are as follows:

[0083] The substrate with the upper Cu metal etched was placed in the etching solution, the etching temperature was set to 40°C, the etching time was 2 minutes, and its various properties were tested after the etching was completed.

[0084] Specifically, 10L of etching solution was poured into the mini etching device, and etching was performed after the temperature reached 40±0.1°C. The total etching time was 2 minutes. The substrate was rinsed with deionized water within 2 seconds after the etching was completed, and the surface moisture was blown dry after rinsing. After the completion, a scanning electron microscope was used for observation, and the performance parameters after etching were further evaluated.

[0085] The performance parameter evaluation criteria are as follows:

[0086] ①, ITO residue: After drying the treated substrate, use a scanning electron microscope (at 30K magnification) to analyze whether there is ITO residue;

[0087] ○: If more than 5 particles protruding from the surface of the sample and with a particle size greater than 0.1 μm can be observed in the SEM image, it means that there is residue;

[0088] ×: If the SEM image shows less than 5 particles protruding from the surface of the sample and with a particle size greater than 0.1 μm, it means there is no residue;

[0089] ② Side etching: After cleaning and drying the etched substrate, prepare the sample, and then use a scanning electron microscope (SEM) to magnify it 30K times to observe the pattern line width.

[0090] ○: CD loss ≤ 0.4 μm;

[0091] ×: CD loss>0.4μm.

[0092] ③Copper corrosion resistance test: Soak the substrate with copper layer in 40℃ ITO etching solution for 10 minutes, then clean and dry it, measure the copper surface resistance, and observe the change of resistance value.

[0093] ○: resistance change <10%;

[0094] ×: Resistance change ≥ 10%.

[0095] ④ Etching stability / lifespan: prepare 10kg of ITO etching solution, gradually add ITO powder to the etching solution until CDloss>0.5μm or the resistance change in the copper corrosion test is ≥15%, then calculate the total amount of ITO powder added.

[0096] ○:>3000ppm;

[0097] ×: 0-3000ppm.

[0098] The test results of the performance parameters of the ITO etching solutions in the embodiments and comparative examples are shown in Table 2.

[0099] Table 2

[0100]

[0101]

[0102] From Table 2 and Figure 1 to Figure 2 It can be seen that when the ITO etching solution of Examples 1-10 is used to perform etching, it is shown that the ITO etching solution of the present invention has an excellent effect.

[0103] From Table 2 and Figures 1 to 4 It can be seen that, compared with Example 1-2, Comparative Examples 1-6 and Comparative Examples 11-12, it can be found that the content of any one of boric acid, silicic acid, hydroxyethyl diphosphonic acid or chloride salt is too low, and ITO residue occurs. If the content of any one of boric acid, silicic acid, hydroxyethyl diphosphonic acid or chloride salt is too high, it will lead to side etching CD loss>2μm. Among them, the content of silicic acid or hydroxyethyl diphosphonic acid in Comparative Examples 4, Comparative Examples 6 and Comparative Examples 12 is too low, which also leads to a decrease in the stability of the ITO etching solution; silicic acid will continue to ionize hydrogen ions during the reaction process, effectively participate in the reaction, and is more conducive to maintaining the stability of the ITO etching solution. Comparative Example 13 replaces silicic acid with acetic acid, and the stability of the ITO etching solution is reduced; Comparative Examples 14-17 use nitric acid and / or acetic acid instead of boric acid and silicic acid, respectively, and all cannot achieve the reduction of copper corrosion while improving the stability of the ITO etching solution. Comparative Example 18 uses acetic acid to replace the hydroxyethyl diphosphonic acid in Example 1, and the entire formulation system is more corrosive to copper. Comparative Example 19 uses 1,2,3 triazole, and it can be found that its corrosion inhibition effect on copper is lower than that of pentaaminotetrazolyl and pentamethyltetrazolyl, and the entire formulation system is more corrosive to copper.

[0104] Comparative Examples 7-10 compared with Examples 1-2 show that when the amount of corrosion inhibitor is too much, the pH increases, the acidity decreases, and the service life does not reach 3000ppm. When the corrosion inhibitor is added too little, the corrosion of copper by the etching solution will be aggravated. It can also be seen from the above test results that when the ITO etching solution includes 1.0wt% to 5.00wt% of boric acid, 5.0wt% to 20wt% of silicic acid, 20wt% to 30wt% of hydroxyethylidene diphosphonic acid, 0.1wt% to 0.5wt% of corrosion inhibitor and the balance of water, it has a better etching performance.

[0105] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An ITO etching solution, characterized in that Calculated by mass percentage, the ITO etching solution comprises 1.0wt% to 5.00wt% of boric acid, 5.0wt% to 20wt% of silicic acid, 20wt% to 30wt% of hydroxyethylidene diphosphonic acid, 0.1wt% to 0.5wt% of corrosion inhibitor and the balance of water.

2. The ITO etching solution according to claim 1, characterized in that The corrosion inhibitor is a nitrogen azole compound, and the corrosion inhibitor is selected from at least one of pentamethyltetrazolyl and pentaaminotetrazolyl.

3. The ITO etching solution according to claim 1, characterized in that The ITO etching solution also includes chloride salt, and the mass fraction of the chloride salt is 5wt% to 10wt%.

4. The ITO etching solution according to claim 3, characterized in that The chloride salt is selected from at least one of ammonium chloride, sodium chloride and potassium chloride.

5. The ITO etching solution according to claim 3, characterized in that Calculated by mass percentage, the ITO etching solution comprises 3.00wt% to 5.00wt% of boric acid, 10wt% to 20.00wt% of silicic acid, 25wt% to 30.00wt% of hydroxyethylidene diphosphonic acid, 0.3wt% to 0.5wt% of corrosion inhibitor, 7.5wt% to 10.00wt% of chloride salt and the balance of water.

6. The ITO etching solution according to claim 5, characterized in that The ITO etching solution comprises 3.00 wt % of boric acid, 10 wt % of silicic acid, 25 wt % of hydroxyethylidene diphosphonic acid, 0.3 wt % of corrosion inhibitor, 7.5 wt % of chloride salt and the balance of water.

7. A method for preparing the ITO etching solution according to any one of claims 1 to 6, characterized in that: include: Mix the components in proportion.

8. The preparation method of ITO etching solution according to claim 7, wherein include: Water, silicic acid and hydroxyethylidene diphosphoric acid are mixed to obtain a mixture, and the mixture is mixed with the remaining components to obtain the ITO etching solution.

9. A method for using the ITO etching solution according to any one of claims 1 to 6, characterized in that: include: The Cu / ITO film to be etched is brought into contact with the ITO etching solution to etch the Cu / ITO film to be etched.

10. The method for using the ITO etching solution according to claim 9, characterized in that: The etching temperature is 35°C to 45°C.

Images