Selective etching solution for titanium and / or copper metal layer of circuit board and preparation method of selective etching solution

Abstract

The invention discloses a selective etching solution for a titanium and / or copper metal layer of a circuit board and a preparation method of the selective etching solution, and the selective etching solution comprises the following components: 10-20% of persulfate, 4-8% of o-nitrobenzenesulfonate, 0.5-1% of phosphoric acid, 0.2-0.8% of 3-(aminomethyl) pyrazole, 0.3-1.5% of ammonium fluoride, 2-5% of cyclohexanediamine tetraacetic acid, 0.1-0.5% of cyclodextrine and the balance of water. The etching solution can selectively etch a titanium and / or copper metal layer, through selection and cooperation of etching solution components, etching is uniform and stable, taper angle and lateral etching control is good, metal wires are smooth, no metal residues exist, and a good etching solution is provided for the circuit board etching process.

Description

Technical Field

[0001] The present invention relates to the field of circuit board etching solutions, and specifically to a selective etching solution for titanium and / or copper metal layers of circuit boards and a preparation method thereof. Background Art

[0002] Circuit board etching solutions are mainly used to etch the unnecessary copper parts on circuit boards to form the required circuit patterns. Common etching objects include the inner and outer layers of rigid circuit boards. During the etching process, the selection of the etching solution is crucial because it directly affects the accuracy and quality of high-density fine wire images. The etching solution usually includes oxidants, complexing agents, buffers, corrosion aids, stabilizers, surfactants, and other additives. Circuit boards are the basis for the preparation of display devices, and etching the multi-layer metal layer to form metal wires is one of the key steps. Therefore, the performance of the etching solution also largely determines the performance of the circuit board. Multi-layers containing metals or alloys such as copper, titanium, and tungsten are common structures of circuit boards. How to develop targeted etching solutions is the pursuit and goal of most electronics factories.

[0003] Patent CN 107475715 A discloses an etching composition. By including the hydrogen peroxide stabilizer of the present invention, high-selectivity etching of a single film or a dual metal film such as copper can be performed, and the decomposition reaction of hydrogen peroxide can be inhibited to perform a stable etching process.

[0004] Patent CN 108456885 A discloses an etching solution composition, which contains persulfate, fluorine-containing compounds, 4-azacyclic compounds, dichlorides, and water. The content ratio of the 4-azacyclic compounds to the dichlorides is 1:1.4 to 1:2. Compared with the existing non-hydrogen peroxide-based etching solutions, it has high storage stability, no deposits occur, and has a high etching rate for metals, and the aging performance is also greatly improved.

[0005] Problems such as etching uniformity, etching cone angle, side etching, metal residue, and over-etching often exist during the etching process of the etching solution. Moreover, as the etching process progresses, the dissolved metal ions also exert great pressure on the stability of the etching solution. The above aspects are the key points, difficulties, and also the continuous pursuit in the industry. Summary of the Invention

[0006] Based on the deficiencies and demands existing in the prior art, the purpose of the present invention is to provide a selective etching solution for titanium and / or copper metal layers of circuit boards and a preparation method thereof, which can selectively etch titanium and / or copper metal layers. Through the selection and coordination of the components of the etching solution, uniform and stable etching, good control of the cone angle and side etching, smoothness of metal wires, and no metal residue are achieved, providing a good etching solution for the circuit board etching process.

[0007] To solve the above technical problems, the present invention provides the following technical solutions for implementation:

[0008] A selective etching solution for titanium and / or copper metal layers of a circuit board, by mass percentage, contains the following components: persulfate 10 - 20%,

[0009] o-nitrobenzenesulfonate 4 - 8%,

[0010] phosphoric acid 0.5 - 1%,

[0011] 3-(aminomethyl)pyrazole 0.2 - 0.8%,

[0012] ammonium fluoride 0.3 - 1.5%,

[0013] cyclohexanediaminetetraacetic acid 2 - 5%

[0014] cyclodextrin 0.1 - 0.5%, and the balance is water.

[0015] Further, the etching solution, by mass percentage, contains the following components:

[0016] persulfate 13 - 16%,

[0017] o-nitrobenzenesulfonate 5 - 6%,

[0018] phosphoric acid 0.7 - 0.8%,

[0019] 3-(aminomethyl)pyrazole 0.4 - 0.6%,

[0020] ammonium fluoride 0.5 - 1%,

[0021] cyclohexanediaminetetraacetic acid 3 - 4%,

[0022] cyclodextrin 0.2 - 0.3%, and the balance is water.

[0023] Further, the etching solution, by mass percentage, consists of the following components:

[0024] persulfate 13 - 16%,

[0025] o-nitrobenzenesulfonate 5 - 6%,

[0026] phosphoric acid 0.7 - 0.8%

[0027] 3-(aminomethyl)pyrazole 0.4 - 0.6%,

[0028] ammonium fluoride 0.5 - 1%,

[0029] cyclohexanediaminetetraacetic acid 3 - 4%,

[0030] cyclodextrin 0.2 - 0.3%, and the balance is water.

[0031] This application does not select strong oxidizing substances such as nitric acid as the oxidant, but selects persulfate with slightly weaker oxidizing ability as the main oxidant; and avoids using hydrogen peroxide, which can essentially solve the problem that hydrogen peroxide is prone to decomposition. However, the persulfate oxidant has a low etching rate and is easily affected by the accumulated metal ions in the etching solution, resulting in premature failure of the etching solution. To solve this defect, the applicant seeks to add o-nitrobenzenesulfonate as an auxiliary oxidant, which can effectively improve the etching rate and stability. The structure of sodium o-nitrobenzenesulfonate contains -NO 2 group, and its oxidizing ability is weaker than that of nitric acid, but higher than that of persulfate. The oxidizing ability between the two makes the etching solution not cause excessive etching of the metal layer due to too strong oxidizing ability. Further, by optimization, the mass percentage of o-nitrobenzenesulfonate is determined to be 4-8%.

[0032] Further, the o-nitrobenzenesulfonate is one or more of sodium o-nitrobenzenesulfonate and potassium o-nitrobenzenesulfonate.

[0033] Further, the persulfate is selected from one or more of sodium persulfate, potassium persulfate, and ammonium persulfate.

[0034] The content of persulfate is controlled at 10-20%. When the content of persulfate is less than 10%, due to the small amount of persulfate, the problem that the main oxidant cannot effectively play its role and effect occurs. At the same time, when the content of persulfate is greater than 20%, due to the excessive relative content of persulfate, an excessive etching phenomenon of the copper-containing metal film will occur.

[0035] This application uses 3-(aminomethyl)pyrazole as a side etching inhibitor of the etching solution, which can effectively inhibit side etching and reduce the amount of side etching.

[0036] In this application, cyclohexanediaminetetraacetic acid is used as a complexing agent. The complexing agent can form stable complexes with Cu and Ti metal ions etched into the etching solution, avoiding the problem of decreased etching ability due to the accumulated Cu and Ti metal ions. However, the complexing agent cannot completely avoid the influence brought by metal ions. Cyclodextrin is a class of cyclic oligosaccharides usually formed by 6, 7, or 8 glucose molecules connected end to end, with a unique spatial structure - a cylindrical hollow structure, whose cavity shows lipophilicity and the periphery shows hydrophilicity. Adding cyclodextrin with this special structure in this application can "fix" metal ions and thus prevent the re-adsorption of Cu and Ti metal ions on the circuit board surface, thereby preventing poor etching and improving the quality; in addition, the inclusion effect of cyclodextrin may help improve the selectivity of the etching solution, so as to achieve more precise pattern control during the etching process. Further, based on its hydrophilicity, a thin film is adsorbed on the surface of the metal layer, avoiding pits caused by uneven etching on the surface of the metal layer and improving the smoothness of the metal wire.

[0037] Further, the cyclodextrin may be α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin.

[0038] A method for preparing a selective etching solution for a titanium and / or copper metal layer of a circuit board as described above, comprising the step of dissolving each component in water and mixing them.

[0039] An application of a selective etching solution for a titanium and / or copper metal layer of a circuit board as described above, wherein the etching solution composition is applied to the preparation of a thin film transistor liquid crystal display panel.

[0040] Further, the titanium and / or copper metal layer has a film layer structure of two or more layers.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) In the present application, persulfate is used as the main oxidant and o-nitrobenzenesulfonate is used as the auxiliary oxidant, avoiding the use of hydrogen peroxide, and essentially solving the problem that hydrogen peroxide is prone to decomposition; and based on the combined use of the two, the etching rate and the stability of the etching rate can be effectively improved.

[0043] (2) The etching solution provided by the present invention will not over-etch the metal layer, can effectively reduce the amount of side etching, and also shows obvious advantages in controlling the cone angle, and can also well prevent the generation of metal residues.

[0044] (3) The etching solution provided by the present invention can improve the surface smoothness of the etched metal wire, reduce the metal wire defects, and form a fine pattern, providing a good guarantee for the quality of the display device.

[0045] (4) The etching solution provided by the present invention can still maintain a good etching rate after being used multiple times, effectively improving the service life and reducing the production cost. Detailed Embodiments

[0046] The following further describes the detailed embodiments of the present invention. It should be noted here that the description of these embodiments is for helping to understand the present invention, but does not constitute a limitation to the present invention.

[0047] Example 1

[0048] A selective etching solution for a titanium and / or copper metal layer of a circuit board as described above, by mass percentage, consists of the following components,

[0049] Sodium persulfate 13%,

[0050] Sodium o-nitrobenzenesulfonate 5%,

[0051] Phosphoric acid 0.7%,

[0052] 3-(Aminomethyl)pyrazole 0.4%,

[0053] Ammonium fluoride 0.5%,

[0054] Cyclohexanediaminetetraacetic acid 3%,

[0055] Cyclodextrin 0.2%,

[0056] Water balance.

[0057] Example 2

[0058] A selective etching solution for titanium and / or copper metal layers of a circuit board as described above, by mass percentage, consists of the following components,

[0059] Potassium persulfate 16%,

[0060] Potassium o-nitrobenzenesulfonate 6%,

[0061] Phosphoric acid 0.8%,

[0062] 3-(Aminomethyl)pyrazole 0.6%,

[0063] Ammonium fluoride 1%,

[0064] Cyclohexanediaminetetraacetic acid 4%,

[0065] Cyclodextrin 0.3%,

[0066] Water balance.

[0067] Example 3

[0068] A selective etching solution for titanium and / or copper metal layers of a circuit board as described above, by mass percentage, consists of the following components,

[0069] Ammonium persulfate 14%,

[0070] Sodium o-nitrobenzenesulfonate 5.5%,

[0071] Phosphoric acid 0.75%,

[0072] 3-(Aminomethyl)pyrazole 0.5%,

[0073] Ammonium fluoride 0.7%,

[0074] Cyclohexanediaminetetraacetic acid 35%,

[0075] Cyclodextrin 0.25%, water balance.

[0076] To investigate the influence of components on the etching solution of the present application, taking Example 3 as a benchmark, single factors were adjusted respectively as control groups for evaluation. Since the functions of ammonium persulfate, ammonium fluoride, and cyclohexanediaminetetraacetic acid in the etching solution are known, they will not be elaborated here. The present application mainly judges the influence of o-nitrobenzenesulfonate, 3-(aminomethyl)pyrazole, and cyclodextrin on it.

[0077] Comparative Example 1

[0078] Comparative Example 1 is basically the same as Example 3, except that sodium o-nitrobenzenesulfonate is not added to the etching solution in Comparative Example 1.

[0079] Comparative Example 2

[0080] Comparative Example 2 is basically the same as Example 3, except that 3-(aminomethyl)pyrazole is not added to the etching solution in Comparative Example 2.

[0081] Comparative Example 3

[0082] Comparative Example 3 is basically the same as Example 3, except that cyclodextrin is not added to the etching solution in Comparative Example 3.

[0083] Preparation of the etching solutions of Examples 1-3 and Comparative Examples 1-3: Each component was dissolved in water and mixed to obtain it.

[0084] The etching solutions prepared in Examples 1-3 and Comparative Examples 1-3 were used for the manufacture of an array substrate for a display device. The manufacturing steps can adopt the existing manufacturing steps, and the present invention has no special limitation; specifically, the etching solution was used to etch the array substrate to form a gate wiring, where the gate wiring is a Ti / Cu double layer. The results of the etching solution in etching the Ti / Cu double layer to form the gate wiring were detected and / or measured, and the specific data are recorded in Table 1.

[0085] Table 1

[0086]

[0087] From the above data, it can be seen that:

[0088] (1) The etching solution of the present invention has a relatively high etching rate, and the etching solution still maintains a relatively high etching rate after processing 10 batches of substrates. Although it has decreased somewhat compared with that, it can still exhibit a good etching effect. This shows that the etching solution provided by the present invention has excellent stability, can be used multiple times, and can significantly reduce the etching cost.

[0089] The difference between Comparative Example 1 and Example 3 lies in the use of sodium o-nitrobenzenesulfonate. From the data, the reduction rate of the etching solution in Example 3 for 10 batches is 20.9%; the initial etching rate of Comparative Example 1 decreased significantly, from 847 nm·s-1 Reduced to 650 nm·s -1 , and the reduction rate of 10 batches of the etching solution was 36.6%. This shows that sodium o-nitrobenzenesulfonate can effectively improve the etching rate and stability of the etching solution; this is also consistent with the results reflected by the surface condition of the gate wiring. Without adding sodium o-nitrobenzenesulfonate, the surface of the gate wiring is smoother and flatter, which is inferior to that of Example 3. However, the addition of sodium o-nitrobenzenesulfonate has little effect on CD skew and taper angle.

[0090] (2) From the numerical ranges of CD skew and taper angle, it can be judged that the etching characteristics of the etching solutions of Examples 1-3 are excellent, showing good control over taper angle and side etching. In Comparative Example 2, the deviations of CD skew and taper angle are large, showing poor etching characteristics; this indicates that 3-(aminomethyl)pyrazole plays a key role in the etching solution.

[0091] (3) The data of Comparative Example 3 compared with those of Example 3 are mainly reflected in metal residue. After etching with the etching solution of Comparative Example 3, obvious metal residue and pits were observed on the surface of the gate wiring. This shows that cyclodextrin in the etching solution of the present application can improve the surface smoothness of the etched metal wire, reduce the defects of the gate wiring, and form a fine pattern, providing a good guarantee for the quality of the display device.

[0092] In summary, through the selection and combination of the components of the etching solution, the present invention achieves uniform and stable etching, good control over taper angle and side etching, smoothness of the metal wire, and no metal residue, providing a good etching solution for the circuit board etching process.

[0093] The above has elaborated in detail on an etching solution provided by an embodiment of the present invention. Specific embodiments are used herein to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those skilled in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A selective etching solution for titanium and / or copper metal layers of a circuit board, characterized in that: In terms of mass percentage, it contains the following components: Persulfate 10-20%, o-nitrobenzene sulfonate 4-8%, Phosphoric acid 0.5~1%, 3-(Aminomethyl)pyrazole 0.2-0.8%, Ammonium fluoride 0.3~1.5%, Cyclohexanediaminetetraacetic acid 2-5%, Cyclodextrin 0.1~0.5%, Water balance.

2. The selective etching solution according to claim 1, characterized in that: In terms of mass percentage, it contains the following components: Persulfate 13-16%, o-nitrobenzene sulfonate 5-6%, Phosphoric acid 0.7~0.8%, 3-(Aminomethyl)pyrazole 0.4-0.6%, Ammonium fluoride 0.5~1%, Cyclohexanediaminetetraacetic acid 3-4%, Cyclodextrin 0.2~0.3%, Water balance.

3. The selective etching solution according to claim 1, characterized in that: The etching solution is composed of the following components in terms of mass percentage: Persulfate 13-16%, o-nitrobenzene sulfonate 5-6%, Phosphoric acid 0.7~0.8%, 3-(Aminomethyl)pyrazole 0.4-0.6%, Ammonium fluoride 0.5~1%, Cyclohexanediaminetetraacetic acid 3-4%, Cyclodextrin 0.2~0.3%, Water balance.

4. The selective etching solution according to any one of claims 1 to 3, characterized in that: The persulfate is selected from one or more of sodium persulfate, potassium persulfate and ammonium persulfate.

5. The selective etching solution according to any one of claims 1 to 3, characterized in that: The o-nitrobenzene sulfonate is one or more of sodium o-nitrobenzene sulfonate and potassium o-nitrobenzene sulfonate.

6. The selective etching solution according to any one of claims 1 to 3, characterized in that: The cyclodextrin is selected from α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin.

7. A method for preparing a selective etching solution for titanium and / or copper metal layers of a circuit board as claimed in any one of claims 1 to 6, characterized in that: The method comprises the steps of dissolving each component in water and mixing.

8. Use of the selective etching solution for titanium and / or copper metal layers of a circuit board as claimed in any one of claims 1 to 6, wherein the etching solution is used for preparing a thin film transistor liquid crystal display panel.

9. The use of the selective etching solution according to claim 8, characterized in that: The titanium and / or copper metal layer is a film layer structure of two or more layers.

Images