Silver film etching solution and application thereof

Abstract

The invention belongs to the technical field of etching, and particularly discloses a silver film etching solution which comprises the following raw materials in percentage by mass: 30-40% of phosphoric acid, 5-10% of nitric acid, 5-10% of acetic acid, 0.01-0.05% of a porphyrin compound, 0.01-0.05% of a guanidine derivative, 5-10% of a dispersing agent, 1-5% of a stabilizer and the balance of water. The silver film etching solution provided by the invention has a stable etching rate, and can well solve the problems of silver residue, silver after-tack and the like at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of etching, and in particular relates to a silver film etching solution and application thereof. Background Art

[0002] In recent years, OLED displays have received extensive attention due to their excellent characteristics such as self-luminescence, no need for backlight, high contrast, thin thickness, wide viewing angle, fast response speed, wide operating temperature range, and simple construction process. Therefore, they have developed rapidly in the past decade and achieved great success. Among them, ITO-Ag-ITO etching liquid, the core material of OLED, is a crucial part of the OLED process and is a key chemical used to thin the silver film. As a light reflector, the quality and efficiency of the silver film directly affect the performance of the final product.

[0003] Common ITO-Ag-ITO etching solutions are mostly phosphoric acid-nitric acid-acetic acid systems, with phosphoric acid as the main source of hydrogen ions, nitric acid providing oxidizing properties during the etching process, and acetic acid as a buffer component. Silver ions in the solution will "stick back" to the substrate surface in the form of metallic silver, resulting in problems such as silver metal residue and silver sticking back, which greatly affects the service life of the display. Summary of the invention

[0004] The purpose of the present invention is to overcome the problem of silver precipitation after etching in conventional silver etching solutions in the prior art, and to provide a silver thin film etching solution, which has a stable etching rate and can also well solve the problems of silver residue and silver back-adhesion.

[0005] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0006] In a first aspect, the present invention provides a silver film etching solution, which comprises the following raw materials, measured by mass percentage: 30%-40% phosphoric acid, 5%-10% nitric acid, 5%-10% acetic acid, 0.01%-0.05% porphyrin compound, 0.01%-0.05% guanidine derivative, 5%-10% dispersant, 1%-5% stabilizer, and the balance is water.

[0007] Furthermore, the porphyrin compound is one or more of aminoporphyrin, sulfonate porphyrin and carboxyl porphyrin.

[0008] Furthermore, the aminoporphyrin is tetrakis(4-aminophenyl)porphyrin;

[0009] The carboxyl porphyrin is one or more of tetrakis(4-carboxyphenyl)porphyrin, tetrakis(3,5-dicarboxyphenyl)porphyrin, and tetrakis(4-carboxy-1,1'-biphenyl)porphyrin;

[0010] The sulfonate porphyrin is tetraphenylporphyrin tetrasulfonic acid.

[0011] Furthermore, the guanidine derivative is one or more of guanidine acetate, β-guanidine propionate, guanidine phosphate, guanidine methanesulfonate, guanidine sulfamate, and aminoguanidine nitrate.

[0012] Furthermore, the dispersant is one or more of polyethylene glycol, polyvinyl alcohol, and sodium polyacrylate.

[0013] Furthermore, the stabilizer is one or more of citric acid, phytic acid, and mercaptopropionic acid.

[0014] In a second aspect, the present invention provides a use of the silver thin film etching solution provided by an embodiment of the first aspect of the present invention in etching a silver thin film.

[0015] Furthermore, the silver thin film is a single-layer film or a multi-layer film.

[0016] Further, the single-layer film is a single-layer film composed of silver or a silver alloy;

[0017] The multilayer film is a multilayer film composed of the single-layer film and a transparent conductive film.

[0018] Furthermore, the material of the transparent conductive film is one or more of indium tin oxide, indium zinc oxide, indium tin zinc oxide and indium gallium zinc oxide.

[0019] Furthermore, the multilayer film composed of the single-layer film and the transparent conductive film is transparent conductive film / silver, transparent conductive film / silver alloy, transparent conductive film / silver / transparent conductive film, or transparent conductive film / silver alloy / transparent conductive film.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The silver thin film etching solution provided by the present invention comprises phosphoric acid, nitric acid, acetic acid, porphyrin compounds, guanidine derivatives, dispersants, stabilizers and water. Phosphoric acid is used as a main etching agent, and nitric acid and acetic acid are used as auxiliary etching agents, which greatly promotes the oxidation of silver in the etching solution and controls the stability of the silver etching rate to meet the requirements of the etching process time. The stabilizer is selected from citric acid, phytic acid, and mercaptopropionic acid, which can effectively buffer the speed of the oxidation reaction of silver, thereby playing a role in stabilizing the silver etching rate in the etching solution in the form of a buffer.

[0022] 2. The silver film etching solution provided by the present invention introduces a porphyrin compound as a chelating agent. Porphyrin is a highly flexible ligand. After the hydrogen atom at the center of the porphyrin ring is ionized, the cavity formed can be complexed with metal ions to form a metal porphyrin complex. Therefore, porphyrin can also be complexed with silver ions to form a complex. In addition, porphyrin has a large volume, and the silver ions can be completely wrapped, forming a steric effect, and cannot be completely ionized, which plays a certain buffering role, preventing the silver ions from sticking back to the substrate surface in the form of elemental silver, thereby solving the problem of etched silver residue. At the same time, the guanidine derivative belongs to the Schiff base compound, contains a C=N bond, and the N atom on its hybrid orbit has a lone pair of electrons, has good flexibility and complexing properties, and can react with silver ions to form a stable compound. There is a synergistic effect between the porphyrin compound of the present invention and the guanidine derivative, which captures free silver ions for complexing to form different soluble silver complexes, effectively preventing the silver ions from returning to the substrate in the form of elemental silver, thereby reducing the silver residue phenomenon.

[0023] 3. In the silver thin film etching solution provided by the present invention, the dispersant is selected from polyethylene glycol, polyvinyl alcohol, and sodium polyacrylate, which can not only disperse the components in the etching solution, but also be adsorbed on the surface of silver particles to form a double electric layer structure, thereby modifying the surface of the dispersed silver particles and generating a repulsive effect between the dispersed silver particles to maintain the dispersion of the silver particles, so that the silver particles are no longer deposited on the surface of the substrate.

[0024] 4. The present invention uses two forms of silver complex and silver particle micelle to interact with each other and effectively reduce the silver metal residue and silver back-adhesion phenomenon. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0026] Figure 1 This is a SEM image of the silver residue on the surface of an ITO-Ag-ITO test piece etched by the silver thin film etching solution provided in Example 1 of the present invention;

[0027] Figure 2 This is a SEM image of the silver residue on the surface of an ITO-Ag-ITO test piece etched by the silver thin film etching solution provided in Example 2 of the present invention;

[0028] Figure 3 This is a SEM image of the silver residue on the surface of the ITO-Ag-ITO test piece etched by the silver thin film etching solution provided in Example 3 of the present invention;

[0029] Figure 4 This is a SEM image of the silver residue on the surface of the ITO-Ag-ITO test piece etched by the silver thin film etching solution provided in Example 4 of the present invention;

[0030] Figure 5 This is a SEM image of the silver residue on the surface of the ITO-Ag-ITO test piece etched by the silver thin film etching solution provided in Example 5 of the present invention;

[0031] Figure 6 This is a SEM image of the silver residue on the surface of the ITO-Ag-ITO test piece etched by the silver thin film etching solution provided in Example 6 of the present invention;

[0032] Figure 7 This is a SEM image of the silver residue on the surface of the ITO-Ag-ITO test piece etched by the silver thin film etching solution provided in Comparative Example 1 of the present invention;

[0033] Figure 8 This is a SEM image of the silver residue on the surface of the ITO-Ag-ITO test piece etched by the silver thin film etching solution provided in Comparative Example 2 of the present invention;

[0034] Fig. 9 This is a SEM picture of the silver residue on the surface of the ITO-Ag-ITO test piece etched by the silver thin film etching solution provided in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Example 1

[0037] The present embodiment provides a silver film etching solution, which is composed of the following raw materials in terms of mass percentage: 30% phosphoric acid, 10% nitric acid, 10% acetic acid, 0.01% porphyrin compound, 0.01% guanidine derivative, 5% dispersant, 1% stabilizer, and the balance is water;

[0038] The porphyrin compound is tetraphenylporphyrin tetrasulfonic acid; the guanidine derivative is guanidine acetate; the stabilizer is mercaptopropionic acid; and the dispersant is sodium polyacrylate.

[0039] Example 2

[0040] The present embodiment provides a silver film etching solution, which is composed of the following raw materials in terms of mass percentage: 35% phosphoric acid, 8% nitric acid, 8% acetic acid, 0.03% porphyrin compound, 0.03% guanidine derivative, 8% dispersant, 3% stabilizer, and the balance is water;

[0041] The porphyrin compound is tetrakis(4-carboxyphenyl)porphyrin; the guanidine derivative is guanidine phosphate; the stabilizer is citric acid; and the dispersant is polyvinyl alcohol.

[0042] Example 3

[0043] The present embodiment provides a silver film etching solution, which is composed of the following raw materials in terms of mass percentage: 40% phosphoric acid, 5% nitric acid, 5% acetic acid, 0.05% porphyrin compound, 0.05% guanidine derivative, 10% dispersant, 5% stabilizer, and the balance is water;

[0044] The porphyrin compound is tetrakis(4-aminophenyl)porphyrin; the guanidine derivative is aminoguanidine nitrate; the stabilizer is a mixture of citric acid and phytic acid in a mass ratio of 1:1; and the dispersant is polyethylene glycol.

[0045] Example 4

[0046] The present embodiment provides a silver film etching solution, which is composed of the following raw materials in terms of mass percentage: 30% phosphoric acid, 10% nitric acid, 10% acetic acid, 0.01% porphyrin compound, 0.01% guanidine derivative, 5% dispersant, 1% stabilizer, and the balance is water;

[0047] The porphyrin compound is obtained by mixing tetraphenylporphyrin tetrasulfonic acid and tetrakis(3,5-dicarboxyphenyl)porphyrin in a mass ratio of 1:1; the guanidine derivative is guanidine acetate; the stabilizer is mercaptopropionic acid; and the dispersant is sodium polyacrylate.

[0048] Example 5

[0049] The present embodiment provides a silver film etching solution, which is composed of the following raw materials in terms of mass percentage: 30% phosphoric acid, 10% nitric acid, 10% acetic acid, 0.01% porphyrin compound, 0.01% guanidine derivative, 5% dispersant, 1% stabilizer, and the balance is water;

[0050] The porphyrin compound is obtained by mixing tetraphenylporphyrin tetrasulfonic acid, tetrakis(3,5-dicarboxyphenyl)porphyrin and tetrakis(4-aminophenyl)porphyrin in a mass ratio of 1:1:1; the guanidine derivative is guanidine acetate; the stabilizer is mercaptopropionic acid; and the dispersant is sodium polyacrylate.

[0051] Example 6

[0052] The present embodiment provides a silver film etching solution, which is composed of the following raw materials in terms of mass percentage: 30% phosphoric acid, 10% nitric acid, 10% acetic acid, 0.01% porphyrin compound, 0.01% guanidine derivative, 5% dispersant, 1% stabilizer, and the balance is water;

[0053] The porphyrin compound is tetraphenylporphyrin tetrasulfonic acid; the guanidine derivative is obtained by mixing guanidine acetate and guanidine aminosulfonate in a mass ratio of 1:1; the stabilizer is mercaptopropionic acid; and the dispersant is sodium polyacrylate.

[0054] Comparative Example 1

[0055] This comparative example provides a silver thin film etching solution, which is different from Example 1 only in that no guanidine derivative is added, and is specifically as follows:

[0056] A silver film etching solution, which is composed of the following raw materials in terms of mass percentage: 30% phosphoric acid, 10% nitric acid, 10% acetic acid, 0.01% porphyrin compound, 5% dispersant, 1% stabilizer, and the balance is water;

[0057] The porphyrin compound is tetraphenylporphyrin tetrasulfonic acid; the stabilizer is mercaptopropionic acid; and the dispersant is sodium polyacrylate.

[0058] Comparative Example 2

[0059] This comparative example provides a silver thin film etching solution, which is different from Example 1 only in that no porphyrin compound is added, and is specifically as follows:

[0060] A silver film etching solution, which is composed of the following raw materials, measured by mass percentage: 30% phosphoric acid, 10% nitric acid, 10% acetic acid, 0.01% guanidine derivative, 5% dispersant, 1% stabilizer, and the balance is water;

[0061] The guanidine derivative is guanidine acetate; the stabilizer is mercaptopropionic acid; and the dispersant is sodium polyacrylate.

[0062] Comparative Example 3

[0063] This comparative example provides a silver thin film etching solution, which is different from Example 1 only in that no dispersant is added, and is specifically as follows:

[0064] A silver film etching solution, which is composed of the following raw materials in terms of mass percentage: 30% phosphoric acid, 10% nitric acid, 10% acetic acid, 0.01% porphyrin compound, 0.01% guanidine derivative, 1% stabilizer, and the balance is water;

[0065] The porphyrin compound is tetraphenylporphyrin tetrasulfonic acid; the guanidine derivative is guanidine acetate; and the stabilizer is mercaptopropionic acid.

[0066] Performance Testing

[0067] Take the silver thin film etching solution provided in Example 1-6 and Comparative Example 1-3, set the temperature to 40°C and then increase the temperature. When the temperature reaches 40±0.1°C, perform an etching process of an ITO-Ag-ITO test piece (i.e., a multilayer film in the form of a transparent conductive film / silver / transparent conductive film), and the total etching time is set to 60 seconds. When the etching time of 60 seconds has expired, take out the test piece, wash it with deionized water, dry it with a hot air drying device, and peel off the photoresist. After washing and drying, observe it with a SEM, and observe that the phenomenon that silver is not etched and remains in the part not covered by the photoresist is silver residue, wherein, if Figure 1-9 As shown, Figure 1-6 The silver film etching solution obtained in Example 1-6 is a SEM image of the silver residue on the surface of the ITO-Ag-ITO test piece after 60 seconds of etching. Figure 7-9 The silver film etching solution obtained in Comparative Examples 1-3 was used. After 60 seconds of etching, the SEM image of the silver residue on the surface of the ITO-Ag-ITO test piece was tested, and the silver residue was evaluated at the same time, with ○ being good, i.e., no silver residue; × being bad, i.e., silver residue occurred. The specific results are shown in Table 1.

[0068] Table 1

[0069] Group Residual situation Example 1 ○ Example 2 ○ Example 3 ○ Example 4 ○ Example 5 ○ Example 6 ○ Comparative Example 1 × Comparative Example 2 × Comparative Example 3 ×

[0070] Figure 1-6 The silver film etching solution obtained in Example 1-6 is a SEM image of the silver residue on the surface of the ITO-Ag-ITO test piece after 60s etching. Figure 1-6 It can be seen that there is no residue on the SEM surface, which indicates that the silver film etching solution obtained in the embodiment has a good effect on removing the metallic silver residue.

[0071] Figure 7-9 The silver film etching solution obtained in Comparative Example 1-3 was used. After 60s of etching, the SEM image of the silver residue on the surface of the ITO-Ag-ITO test piece was tested. Figure 7-9 It can be seen that there is a large amount of silver residue on the SEM surface, indicating that the silver film etching solution obtained in the comparative example has a poor effect on removing the metallic silver residue.

[0072] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0073] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A silver thin film etching solution, characterized in that: The invention comprises the following raw materials in percentage by mass: 30%-40% phosphoric acid, 5%-10% nitric acid, 5%-10% acetic acid, 0.01%-0.05% porphyrin compound, 0.01%-0.05% guanidine derivative, 5%-10% dispersant, 1%-5% stabilizer and the balance is water.

2. A silver thin film etching solution according to claim 1, characterized in that, The porphyrin compound is one or more of aminoporphyrin, sulfonic acid porphyrin and carboxyl porphyrin.

3. A silver film etching solution according to claim 2, characterized in that, The aminoporphyrin is tetrakis(4-aminophenyl)porphyrin; The carboxyl porphyrin is one or more of tetrakis(4-carboxyphenyl)porphyrin, tetrakis(3,5-dicarboxyphenyl)porphyrin, and tetrakis(4-carboxy-1,1'-biphenyl)porphyrin; The sulfonate porphyrin is tetraphenylporphyrin tetrasulfonic acid.

4. A silver thin film etching solution according to claim 1, characterized in that, The guanidine derivative is one or more of guanidine acetate, β-guanidine propionate, guanidine phosphate, guanidine methanesulfonate, guanidine sulfamate, and aminoguanidine nitrate.

5. A silver thin film etching solution according to claim 1, characterized in that, The dispersant is one or more of polyethylene glycol, polyvinyl alcohol and sodium polyacrylate.

6. A silver film etching solution according to claim 1, characterized in that: The stabilizer is one or more of citric acid, phytic acid, and mercaptopropionic acid.

7. Use of the silver thin film etching solution according to any one of claims 1 to 6 in etching silver thin film.

8. Use of the silver thin film etching solution according to claim 7 in etching a silver thin film, characterized in that: The silver thin film is a single-layer film or a multi-layer film.

9. Use of the silver thin film etching solution according to claim 7 in etching a silver thin film, characterized in that: The single-layer film is a single-layer film composed of silver or a silver alloy; The multilayer film is a multilayer film composed of the single-layer film and a transparent conductive film.

10. Use of the silver thin film etching solution according to claim 9 in etching a silver thin film, characterized in that: The material of the transparent conductive film is one or more of indium tin oxide, indium zinc oxide, indium tin zinc oxide and indium gallium zinc oxide.

Images