High-selectivity nickel-chromium etching solution for semiconductor flexible circuit board as well as preparation method and application of high-selectivity nickel-chromium etching solution
A selective nickel-chromium etching solution using hydrochloric acid, sulfuric acid, pyridine amide, and polyether compounds addresses the limitations of existing etching solutions by enhancing selectivity and reducing copper corrosion in a single-step process, improving etching efficiency and surface quality.
Patent Information
- Application Number
- CN202411207668.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-30
- Publication Date
- 2024-12-13
AI Technical Summary
Existing nickel-chromium etching solutions for semiconductor flexible circuit boards are highly corrosive and require multiple wet etching processes, limiting their application in high-density integrated circuits where high selectivity, controllability, and compatibility are needed.
A highly selective nickel-chromium etching solution comprising concentrated hydrochloric acid, sulfuric acid, pyridine amide compounds, polyether compounds, and deionized water, which forms stable complexes with nickel and chromium for high selectivity and reduces copper corrosion, while using a one-step etching process.
The solution achieves high selectivity for nickel-chromium metals with low copper corrosion, improving etching rate and surface quality by forming stable complexes and reducing local over-etching risks.
Smart Images
Figure CN119121233A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of semiconductor manufacturing technology, and in particular relates to a highly selective nickel-chromium etching solution for semiconductor flexible circuit boards, and a preparation method and application thereof. Background Art
[0002] Semiconductor flexible printed circuit (FPC) is a thin and flexible electronic circuit board, usually composed of multiple layers of polymer film and conductive layer. Nickel-chromium alloy (NiCr) is used in the semiconductor field FPC for electrodes, wiring, reflective layer and impedance matching due to its good conductivity, corrosion resistance and mechanical strength. Nickel-chromium etching solution is widely used in the semiconductor field to remove nickel-chromium layers, and when these components need to be selectively changed or removed during the manufacturing process, nickel-chromium etching solution can provide an effective etching method.
[0003] In recent years, with the advancement of semiconductor technology and the increasing density of integrated circuits, the demand for nickel-chromium etching solutions has also increased. In the Fine Pitch process used in the manufacture of high-density electronic devices and circuit boards, the selectivity and controllability of nickel-chromium alloy etching solutions are one of its key features. It should have high selectivity, that is, only etching the target nickel-chromium alloy without affecting other materials. In addition, it should have good controllability to achieve the required etching rate, uniformity and precise pattern definition. In addition, for more complex device structures and material combinations, nickel-chromium etching solutions also need to have better compatibility and adaptability.
[0004] At present, the common high-purity nickel-chromium etching solutions based on cerium sulfate and high cerium ammonium nitrate are not only highly corrosive to the substrate material, but also require two wet etching processes, which are gradually limited in their application areas. Therefore, it is necessary to develop a nickel-chromium etching solution with high wettability and high selectivity to nickel-chromium metal under one-step etching process conditions. Summary of the invention
[0005] The technical problem solved by the present invention is to effectively etch fine circuits while having high selectivity for nickel-chromium metals and low corrosion for copper.
[0006] In view of the technical problems existing in the prior art, the present invention designs a highly selective nickel-chromium etching solution for semiconductor flexible circuit boards and a preparation method and application thereof.
[0007] It should be noted that, in the present invention, unless otherwise specified, the specific meaning of "including" in relation to composition limitations and descriptions includes both open-ended "including", "comprising" and similar meanings, and closed-ended "consisting of..." and similar meanings.
[0008] In order to solve the above-mentioned technical problems, the present invention adopts the following solutions:
[0009] A highly selective nickel-chromium etching solution for semiconductor flexible circuit boards, characterized in that it comprises the following components, calculated in parts by weight:
[0010] 8-20 parts of concentrated hydrochloric acid;
[0011] Concentrated sulfuric acid 5-13 parts:
[0012] 1-10 parts of pyridine amide compounds and derivatives;
[0013] 1-8 parts of polyether compounds and derivatives;
[0014] 40-60 parts of deionized water.
[0015] Furthermore, the pyridine amide compounds and derivatives are one or more of 2,6-pyridinedicarboxamide, 2,6-diacetylpyridine, 2-(2-pyridylsulfonyl)thioacetamide, 2-aminopyridine-5-thiocarboxamide, 5-amino-2-pyridinecarboxamide, N-(2,6-dimethylphenyl)-2-pyridinecarboxamide, 2-amino-4,6-dimethyl-3-pyridinecarboxamide, and N-methyl-N-(2-pyridine)carboxamide.
[0016] Furthermore, the polyether compound and its derivatives are one or more of polyethylene ethyl ether, polyethylene glycol octylphenyl ether, polyethylene glycol diglycidyl ether, polyethylene glycol monobutyl ether, isomeric tridecanol polyoxyethylene ether, isopentanol polyoxyethylene ether, and octylphenol polyoxyethylene ether.
[0017] Furthermore, the pyridine amide compound and its derivative are 2-(2-pyridylsulfonyl)thioacetamide or 2-aminopyridine-5-thiocarboxamide.
[0018] Furthermore, the polyether compound and its derivatives are one or more of polyethylene glycol diglycidyl ether, isomeric tridecanol polyoxyethylene ether and octylphenol polyoxyethylene ether.
[0019] The present invention also discloses a method for preparing a highly selective nickel-chromium etching solution for semiconductor flexible circuit boards, which is characterized by comprising the following steps:
[0020] Step 1: Weigh concentrated hydrochloric acid, concentrated sulfuric acid, pyridine amide compounds and derivatives, polyether compounds and derivatives, and deionized water respectively;
[0021] Step 2: Stir the components at room temperature at a speed of 200-1500 r / min for 10-30 min until all materials are completely dissolved, thereby obtaining the highly selective nickel-chromium etching solution for semiconductor flexible circuit boards.
[0022] The present invention also discloses an etching method of a highly selective nickel-chromium etching solution for a semiconductor flexible circuit board, which is characterized by comprising the following steps:
[0023] Step 1: heating the highly selective nickel-chromium etching solution for semiconductor flexible circuit boards to 20-50° C., immersing the FPC flexible circuit board containing the nickel-chromium alloy layer in the etching solution for 0.5-10 minutes to obtain the immersed FPC flexible circuit board;
[0024] Step 2: Rinse the soaked FPC flexible circuit board in ultrapure water for at least two times, and then dry the water stains on its surface with an ultrapure nitrogen flow, thereby completing the surface etching treatment of the FPC flexible circuit board containing the nickel-chromium alloy layer.
[0025] The invention also discloses a use of a highly selective nickel-chromium etching solution for semiconductor flexible circuit boards.
[0026] In the present invention, in order to further optimize the effect of the nickel-chromium etching solution, the various components can be optimized: 9-15 parts of concentrated hydrochloric acid; 8-11 parts of concentrated sulfuric acid; 1-5 parts of pyridine amide compounds and derivatives; 1-4 parts of polyether compounds and derivatives; 45-55 parts of deionized water.
[0027] Concentrated hydrochloric acid is usually used as the main etchant in nickel-chromium metal etching solutions.
[0028] In the present invention, concentrated hydrochloric acid can clean the oxide layer, pollutants and other attachments on the metal surface, provide a clean metal surface for etching and have strong dissolving ability;
[0029] In the present invention, concentrated hydrochloric acid can provide chloride ions, promote the chlorination reaction on the metal surface, and accelerate the dissolution process of the metal. As an important component of the etching solution, concentrated hydrochloric acid plays a vital role in the etching process.
[0030] Concentrated sulfuric acid is commonly used as an oxidant and cleaning agent in nickel-chromium metal etching solutions.
[0031] In the present invention, concentrated sulfuric acid itself has a certain oxidizing property and can oxidize nickel and chromium on the metal surface and convert them into soluble ion forms, thereby promoting the etching process.
[0032] In the present invention, concentrated sulfuric acid has good cleaning ability and can remove dirt, oxides, organic matter and other impurities on the surface of nickel and chromium, providing a clean surface for the etching process. As a solubilizing agent, it also helps dissolve other components and maintain the stability and uniformity of the etching solution.
[0033] Pyridine amide compounds and their derivatives play a vital role in the etching of nickel-chromium metals:
[0034] First, as ion-selective ligands, pyridineamide compounds have nitrogen-containing pyridine rings and carbonyl oxygen-containing ligands that can form stable complexes with metal ions such as nickel and chromium with high selectivity; the nitrogen atom in the sulfonyl group can form a more stable complex with the metal ions in the etching solution, and can react more effectively with the nickel-chromium metal surface; the sulfur atom in the thio group can undergo a sulfidation reaction with the metal surface to form a metal sulfide that usually has lower stability and corrosion resistance and is easily dissolved in the etching solution. These changes may promote the electrochemical reaction and facilitate the dissolution and removal of nickel-chromium metals, thereby improving the highly selective etching of metals such as nickel and chromium.
[0035] Second: As corrosion inhibitors, pyridine amide compounds can selectively react with active sites on the surface of copper metal to form a covering layer, blocking the further dissolution of the metal. This covering layer can reduce the contact between the oxidizing substances in the etching solution and the metal, thereby reducing the corrosion rate of metal Cu.
[0036] Third: As a surfactant, it has certain hydrophilicity and lipophilicity, which can reduce the surface tension at the liquid-liquid interface or liquid-solid interface, and promote interaction and dispersion on the interface, adsorb on the metal surface, destroy the protective oxide film on the metal surface, and increase the etching rate of nickel-chromium metal.
[0037] The functions of polyether compounds and their derivatives in etching solutions are as follows:
[0038] First, they can reduce the surface tension of the etching solution. By reducing the surface tension, they can improve the contact between the etching solution and the metal surface, allowing the etching solution to better wet the metal surface, improve the coverage and diffusion of the etching solution, and synergize with other etching components to significantly increase the etching rate.
[0039] Second: Help disperse metal ions, impurities and particulate matter, etc. Inhibit redeposition of etching products. By enhancing dispersibility, they can prevent the precipitation and precipitation of metal ions and maintain the uniformity and stability of the etching solution.
[0040] Third: It contains a large number of ether bonds (COC), which can form stable complexes with metal ions. This complexation can dissolve and remove oxide films and other impurities on the metal surface.
[0041] Fourth, it reduces the activity of other metal ions and inhibits the dissolution rate of metals, thereby controlling the selective dissolution of metals during the etching process.
[0042] The present invention provides a highly selective nickel-chromium etching solution for semiconductor flexible circuit boards and a preparation method and application thereof, which have the following beneficial effects:
[0043] 1. The etching solution of the present invention improves the etching selectivity of nickel and chromium. The pyridine amide compounds and their derivatives and the polyether compounds and their derivatives are used in combination to form complexes with nickel and chromium with high selectivity, thereby improving the selectivity and reducing the corrosion of other metals.
[0044] 2. The surface quality of the etching solution of the present invention is improved. Pyridine amide compounds and derivatives and polyether compounds and derivatives have good surface activity and can form an adsorption layer on the surface of nickel and chromium. The wettability of the liquid on the metal surface can be improved, the etching solution can be evenly distributed, and the risk of local over-etching can be reduced, thereby improving the surface quality after etching. BRIEF DESCRIPTION OF THE DRAWINGS
[0045] Figure 1 : 8000 times magnified SEM pictures of metal nickel-chromium before etching, after etching of Example 1, and after etching of Comparative Example 1;
[0046] Figure 2 : Optical microscope pictures of metal nickel-chromium before etching, after etching of Example 1, and after etching of Comparative Example 1 magnified 822 times. DETAILED DESCRIPTION
[0047] The present invention will be further described below in conjunction with specific embodiments and accompanying drawings:
[0048] Table 1 Example
[0049]
[0050]
[0051] Table 2 Comparative Examples
[0052]
[0053] Table 3 Test data
[0054]
[0055] About the preparation method of the etching solution of the present invention:
[0056] The embodiments and comparative examples of the present invention involve the preparation of multiple sets of etching solutions, which are all prepared according to the following method:
[0057] Step 1: Weigh concentrated hydrochloric acid, concentrated sulfuric acid, pyridine amide compounds and derivatives, polyether compounds and derivatives, and deionized water respectively;
[0058] Step 2: Add each component into a container, stir at room temperature at a speed of 1000 r / min for 20 minutes, until all materials are completely dissolved, to obtain the highly selective nickel-chromium etching solution for semiconductor flexible circuit boards.
[0059] Regarding the etching method of the present invention:
[0060] Step 1: heating the highly selective nickel-chromium etching solution for semiconductor flexible circuit boards to 30° C. in a constant temperature water bath, and immersing the FPC flexible circuit board containing the nickel-chromium alloy layer in the etching solution for 5 minutes to obtain the immersed FPC flexible circuit board;
[0061] Step 2: Rinse the soaked FPC flexible circuit board in ultrapure water for at least two times, and then dry the water stains on its surface with an ultrapure nitrogen flow, thereby completing the surface etching treatment of the FPC flexible circuit board containing the nickel-chromium alloy layer.
[0062] About performance testing and description:
[0063] The test method for performance 1 etching morphology is:
[0064] Under the condition of test temperature of 30℃, the Cu seed layer and the NiCr layer thickness are A flexible circuit board with a size of 2cm×2cm was immersed in the etching solution. After the nickel-chromium layer on the surface was completely etched, it was taken out, the residual liquid on the surface was rinsed with ultrapure water and dried with an ultrapure nitrogen flow, and the cross-sectional morphology and corrosion of the copper metal layer were observed with a scanning electron microscope.
[0065] The test method for performance 2 wettability is:
[0066] Under the condition of test temperature of 30℃, the Cu seed layer and the NiCr layer thickness are A flexible circuit board of size 2cm×2cm was immersed in the etching solution, and taken out after the nickel-chromium layer on the surface was completely etched. The residual liquid on the surface was rinsed with ultrapure water and dried with an ultrapure nitrogen flow. The surface morphology of the flexible circuit board was observed with an optical microscope.
[0067] The test method for performance 3 etching rate is:
[0068] Under the condition of test temperature of 30℃, a 2cm×2cm nickel-chromium alloy layer with a thickness of The thickness of the 2cm×2cm copper layer is The flexible circuit boards were immersed in nickel-chromium etching solution, taken out at a fixed time, the residual liquid on the surface was rinsed with ultrapure water and dried with ultrapure nitrogen flow, the film thickness before and after etching was tested by a four-probe resistivity tester, and the etching rate was obtained by calculation.
[0069] Analysis of the test results:
[0070] In Comparative Example 1, due to the lack of the addition of pyridine amide compounds and derivatives, there is a lack of selective coordination to nickel-chromium metal, and it is unable to slow down the corrosion of copper metal. Therefore, the etching rate of the etching solution on the nickel-chromium alloy is significantly reduced, and obvious corrosion is caused to the copper metal.
[0071] In Comparative Example 2, due to the lack of addition of polyether compounds and derivatives, the coverage and diffusivity of the etching solution are reduced, and the solubility of the metal etching product becomes worse. Therefore, the etching solution reduces the dispersibility of nickel-chromium metal ions, etching uniformity and protection of copper metal, reduces the etching rate of nickel-chromium alloy, and causes corrosion to copper metal.
[0072] The etching solution prepared in the embodiment has a high etching rate for NiCr and a low etching rate for Cu.
[0073] Further comparison is made through the attached drawings in the specification:
[0074] Figure 1 The SEM images of metal nickel-chromium before etching, after etching of Example 1, and after etching of Comparative Example 1 are magnified 8000 times; Figure 2 These are optical microscope pictures of metal nickel-chromium before etching, after etching of Example 1, and after etching of Comparative Example 1, magnified 822 times.
[0075] from Figure 1 and Figure 2 It can be seen that there is no residue in Example 1 and the surface morphology of the copper layer is good and basically undamaged; while there is a small amount of residue in Comparative Example 1 and the surface morphology of the copper layer is severely damaged.
[0076] Example 1 has good wettability, and there is no residue between the ultrafine structures; while Comparative Example 1 has poor wettability, and there is a small amount of residue between the structures.
[0077] The etching solution of the present invention improves the nickel-chromium etching selectivity and improves the surface quality of the etching solution. The reason is that the pyridine amide compounds and derivatives and the polyether compounds and derivatives are used in combination to form complexes with nickel-chromium with high selectivity, thereby improving the selectivity and reducing corrosion to other metals. Both have good surface activity characteristics and can form an adsorption layer on the nickel-chromium surface. The wettability of the liquid on the metal surface can be improved, the etching solution can be evenly distributed, and the risk of local over-etching can be reduced, thereby improving the surface quality after etching.
[0078] The present invention is described exemplarily above in conjunction with the embodiments and drawings. It is obvious that the implementation of the present invention is not limited to the above-mentioned methods. As long as various improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.
Claims
1. A highly selective nickel-chromium etching solution for semiconductor flexible circuit boards, characterized in that: Calculated by weight, it includes the following components: 8-20 parts of concentrated hydrochloric acid; Concentrated sulfuric acid 5-13 parts: 1-10 parts of pyridine amide compounds and derivatives; 1-8 parts of polyether compounds and derivatives; 40-60 parts of deionized water.
2. The highly selective nickel-chromium etching solution for semiconductor flexible circuit boards according to claim 1, characterized in that: The pyridine amide compounds and derivatives are one or more of 2,6-pyridinedicarboxamide, 2,6-diacetylpyridine, 2-(2-pyridylsulfonyl)thioacetamide, 2-aminopyridine-5-thiocarboxamide, 5-amino-2-pyridinecarboxamide, N-(2,6-dimethylphenyl)-2-pyridinecarboxamide, 2-amino-4,6-dimethyl-3-pyridinecarboxamide, and N-methyl-N-(2-pyridine)carboxamide.
3. The highly selective nickel-chromium etching solution for semiconductor flexible circuit boards according to claim 1, characterized in that: The polyether compound and its derivatives are one or more of polyethylene ethyl ether, polyethylene glycol octylphenyl ether, polyethylene glycol diglycidyl ether, polyethylene glycol monobutyl ether, isomeric tridecanol polyoxyethylene ether, isopentanol polyoxyethylene ether, and octylphenol polyoxyethylene ether.
4. The highly selective nickel-chromium etching solution for semiconductor flexible circuit boards according to claim 2, characterized in that: The pyridine amide compound and its derivative are 2-(2-pyridylsulfonyl)thioacetamide or 2-aminopyridine-5-thiocarboxamide.
5. The highly selective nickel-chromium etching solution for semiconductor flexible circuit boards according to claim 3, characterized in that: The polyether compound and its derivatives are one or more of polyethylene glycol diglycidyl ether, isomeric tridecanol polyoxyethylene ether and octylphenol polyoxyethylene ether.
6. A method for preparing a highly selective nickel-chromium etching solution for semiconductor flexible circuit boards according to any one of claims 1 to 5, characterized in that The following steps are involved: Step 1: Weigh concentrated hydrochloric acid, concentrated sulfuric acid, pyridine amide compounds and derivatives, polyether compounds and derivatives, and deionized water respectively; Step 2: Stir the components at room temperature at a speed of 200-1500 r / min for 10-30 min until all materials are completely dissolved, thereby obtaining the highly selective nickel-chromium etching solution for semiconductor flexible circuit boards.
7. An etching method for a semiconductor flexible circuit board using a highly selective nickel-chromium etching solution according to any one of claims 1 to 5, characterized in that The following steps are involved: Step 1: heating the highly selective nickel-chromium etching solution for semiconductor flexible circuit boards to 20-50° C., immersing the FPC flexible circuit board containing the nickel-chromium alloy layer in the etching solution for 0.5-10 minutes to obtain the immersed FPC flexible circuit board; Step 2: Rinse the soaked FPC flexible circuit board in ultrapure water for at least two times, and then dry the water stains on its surface with an ultrapure nitrogen flow, thereby completing the surface etching treatment of the FPC flexible circuit board containing the nickel-chromium alloy layer.
8. Use of the highly selective nickel-chromium etching solution for semiconductor flexible circuit boards according to any one of claims 1 to 5.