Anti-electric corrosion copper etching solution for display panel and preparation method and application thereof

Abstract

This invention relates to a copper etching solution for display panels to resist galvanic corrosion, its preparation method, and its application. The copper etching solution for display panels, by weight, comprises the following components: 20-30 parts hydrogen peroxide; 0.5-3 parts inorganic salt; 1-10 parts organic acid; 0.5-3 parts inorganic acid; 5-15 parts surfactant; 1-15 parts metal rate control agent; 0.1-2 parts corrosion inhibitor; and 40-70 parts deionized water. This invention uses a metal rate control agent, which is a glycosaminoglycan, to effectively stabilize the etching rate of copper, thereby controlling the decomposition of hydrogen peroxide by copper ions, stabilizing the pH of the etching solution, and making the etching reaction safer. Simultaneously, functional groups such as -OH and -NH2 are protonated under acidic conditions, and these protonated cations can be adsorbed at the metal-etching solution interface, thus playing a role in metal corrosion inhibition.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor manufacturing processes, and particularly relates to a copper etching solution for display panels that resists galvanic corrosion, its preparation method, and its application. Background Technology

[0002] Since the invention of the transistor by Bell Labs, logic circuits designed using binary control methods have become a reality, the integration level of circuit applications has increased exponentially over time. In large-scale transistor circuits, field-effect transistors (FETs) offer higher control accuracy and are easier to manufacture than other transistor types, thus enjoying widespread application. However, as the integration level of integrated circuits continues to increase, the number of FETs required per unit area increases exponentially, necessitating a continuous reduction in the linewidth of the control circuit. When the linewidth of the control circuit is less than a certain size (e.g., 20 μm or less), photolithography is typically used on integrated circuit production lines. Photolithography involves multiple steps, including cleaning, film deposition, exposure, development, etching, stripping, and inspection. The etching process includes dry etching and wet etching. Under normal circumstances, dry etching involves ionizing a small area with a special gas under plasma conditions to form the relevant pattern; while wet etching involves contacting a metal or oxide film with a chemical agent and removing the unprotected parts through a chemical reaction to form an integrated circuit pattern.

[0003] Copper forms a dense crystalline structure during film deposition and annealing. This structure is difficult to etch using dry etching and is prone to leaving interface residues that can lead to product defects. Therefore, wet etching is commonly used in current manufacturing processes to address this issue.

[0004] Among various types of copper etching solutions, hydrogen peroxide-based copper etching solutions are currently the most widely used. Compared to other copper etching solution systems (such as ferric chloride systems and ammonium persulfate systems), hydrogen peroxide-based copper etching solutions have the advantages of not introducing other metal ions onto the copper layer surface or in the circuit system, producing a more compatible and environmentally friendly product, resulting in less environmental pollution, higher etching efficiency, and a longer service life. Most hydrogen peroxide-based copper etching solutions consist of three parts: hydrogen peroxide components involved in oxidation, inorganic / organic acid components involved in dissolution, and various additives such as copper corrosion inhibitors. The main reaction process is as follows:

[0005] (1) Oxidation process: H2O2+Cu→CuO+H2O

[0006] (2) Dissolution process: CuO + 2H + →Cu 2+ +H2O

[0007] (3) Chelation process: Cu 2+ +n[chelate]→Cu n [chelate]2

[0008] Previous research indicates that the etching rate is primarily influenced by the copper oxidation process, and the dissolution of copper oxide in acidic solutions is almost instantaneous. However, in addition to the aforementioned main reactions, hydrogen peroxide's oxidizing power is higher than that of monovalent copper ions (Cu). + ) and elemental copper (Cu), plus Cu 2+ It has a catalytic effect on the decomposition of hydrogen peroxide. Several side reactions also occur in the above process:

[0009] (4) Copper ion catalyzes the decomposition of hydrogen peroxide: 2H2O2→2H2O+O2↑

[0010] (5) Elemental copper is oxidized by copper ions (in an acidic environment): Cu 2+ +Cu→2Cu +

[0011] (6) Oxidation of monovalent copper: 2Cu + +H₂O₂ + 2H₂ + →2Cu 2+ +2H2O

[0012] On the other hand, when used for gate wiring, the adhesion between the glass substrate and copper is sometimes insufficient, and when used for source / drain wiring, copper can sometimes diffuse into the substrate. To prevent these problems, metals such as molybdenum (Mo) are used as metal barrier films in a stacked configuration. These films have high adhesion to substrates such as glass, are difficult to diffuse into silicon-based materials, and have excellent properties of blocking copper diffusion. However, in hydrogen peroxide-based acidic copper etching solutions, the underlying metal material (referred to as M) can form a galvanic cell reaction with copper and copper ions in the solution due to its potential being either higher or lower than that of copper, thus affecting the etching effect.

[0013] The objective of this application is to develop an etchant that can suppress galvanic cell reactions in multi-metal layer substrates and avoid bottom incision. Under high hydrogen peroxide conditions, the selected metal chelate ensures that the etchant color does not change from blue to green with increasing copper ppm, and no white crystals precipitate in the etchant. Furthermore, the etching rate does not exhibit abrupt changes with increasing ppm, thereby further improving product specifications. The etchant is also safe and poses no risk of sudden boiling. Summary of the Invention

[0014] The technical problem solved by this invention is the harm to product specifications caused by the formation of a certain galvanic cell effect in a multi-metal layer substrate under the environmental conditions containing hydrogen peroxide etching solution.

[0015] In view of the technical problems existing in the prior art, this invention designs a metal rate control agent based on the coordination characteristics of copper ions, focusing on screening agents that can rapidly stabilize copper ions and form stable compounds in the acidic environment of copper etching solution. This improves the defect that the continuous dissolution of copper ions during the etching process causes their concentration to affect the copper etching rate. This etching solution is a high-hydrogen peroxide system copper acid etching solution that can suppress the MTD rate, control the etching of the Cu layer to prevent incision due to the galvanic cell effect, and has a high copper ion loading capacity.

[0016] It should be noted that, in this invention, unless otherwise specified, the specific meaning of "comprising" in relation to composition definition and description includes both open-ended meanings such as "comprising," "including," etc., and closed-ended meanings such as "composed of," etc., and similar meanings.

[0017] To solve the aforementioned technical problems, the present invention adopts the following solution:

[0018] [The first technical solution]

[0019] A copper etching solution for display panels that resists galvanic corrosion, characterized in that it comprises the following components by weight:

[0020] 20-30 parts hydrogen peroxide;

[0021] Inorganic salts 0.5-3 parts;

[0022] 1-10 parts organic acids;

[0023] Inorganic acid 0.5-3 parts;

[0024] 5-15 parts of surfactant;

[0025] Metal rate control agent 1-15 parts;

[0026] Corrosion inhibitor 0.1-2 parts;

[0027] 40-70 parts deionized water;

[0028] The metal rate control agent is a glycosaminoglycan.

[0029] Furthermore, the metal rate control agent is one or more of chondroitin sulfate, hyaluronic acid, and keratin sulfate.

[0030] Furthermore, the inorganic salt is one or more of potassium sulfate, sodium chloride, potassium chloride, potassium nitrate, ammonium nitrate, sodium nitrate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate.

[0031] Further, the inorganic salt is at least two of potassium sulfate, sodium chloride, potassium chloride, potassium nitrate, ammonium nitrate, sodium nitrate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate, and the mass ratio of any two inorganic salts is 1:1 to 5:1.

[0032] Furthermore, the organic acid is one or more of the following: mandelic acid, malic acid, citric acid, tartaric acid, malonic acid, fumaric acid, maleic acid, formic acid, succinic acid, and iminodisuccinic acid.

[0033] Further, the organic acid is at least two of the following: mandelic acid, malic acid, citric acid, tartaric acid, malonic acid, fumaric acid, maleic acid, carboxylic acid, formic acid, succinic acid, and iminodisuccinic acid, and the mass ratio of any two organic acids is 4:1 to 2:1.

[0034] Furthermore, the inorganic acid is one or more of sulfuric acid, phosphoric acid, boric acid, and nitric acid.

[0035] Furthermore, the inorganic acid is at least two of sulfuric acid, phosphoric acid, boric acid, and nitric acid, and the mass ratio of any two inorganic acids is 1:5-2:1.

[0036] Furthermore, the surfactant is a short-chain alcohol, which refers to an alcoholic substance composed of fewer than six carbon atoms.

[0037] Furthermore, the present invention does not specifically limit the surfactant, which can be a short-chain alcohol commonly used in the art, for example, the surfactant is one or more of glycerol, butanediol and triethylene glycol.

[0038] Furthermore, the corrosion inhibitor is an azole, such as one or more of 3-aminotriazole, benzotriazole, 5-aminotetrazole, 6-nitrobenzimidazole, 2-aminothiazole, 4-aminotetrazole, and 3-amino-1,2,4-triazole.

[0039] Further, the corrosion inhibitor is at least two of 3-aminotriazole, benzotriazole, 5-aminotetrazole, 6-nitrobenzimidazole, 2-aminothiazole, 4-aminotetrazole, and 3-amino-1,2,4-triazole, and the mass ratio of any two azole corrosion inhibitors is 1:3 to 2:1.

[0040] In this invention, in order to further optimize the performance of the copper etching solution for display panels that resists galvanic corrosion, the components can be optimized as follows: 20-25 parts hydrogen peroxide; 1-2 parts inorganic salt; 4-8 parts organic acid; 1-1.5 parts inorganic acid; 8-15 parts surfactant; 5-10 parts metal rate control agent; 0.3-1.5 parts corrosion inhibitor; and 48-60 parts deionized water.

[0041] In this invention, the metal rate control agent is preferably chondroitin sulfate.

[0042] In this invention, the inorganic salt is preferably diammonium hydrogen phosphate and diammonium dihydrogen phosphate.

[0043] In this invention, the mass ratio of diammonium hydrogen phosphate to diammonium dihydrogen phosphate is 1:1 to 5:1.

[0044] In this invention, the mass ratio of diammonium hydrogen phosphate to diammonium dihydrogen phosphate is preferably 1:1 to 3:1.

[0045] In this invention, the organic acid is citric acid and iminodisuccinic acid.

[0046] In this invention, the mass ratio of citric acid to iminodisuccinic acid is 4:1-2:1.

[0047] In this invention, the mass ratio of citric acid to iminodisuccinic acid is preferably 3:1 to 1:1.

[0048] In this invention, the inorganic acid is preferably sulfuric acid and boric acid.

[0049] In this invention, the mass ratio of sulfuric acid to boric acid is 1:5-2:1.

[0050] In this invention, the mass ratio of sulfuric acid to boric acid is preferably 1:3 to 1:1.

[0051] In this invention, the surfactant is preferably glycerol.

[0052] In this invention, the corrosion inhibitor is preferably 5-aminotetrazole and 6-nitrobenzimidazole.

[0053] In this invention, the mass ratio of 5-aminotetrazole and 6-nitrobenzimidazole is 1:3-2:1.

[0054] In this invention, the mass ratio of 5-aminotetrazole and 6-nitrobenzimidazole is preferably 1:2 to 1:1.

[0055] In this invention, the metal rate control agent in the copper etching solution for display panels that resists galvanic corrosion plays a unique role:

[0056] Firstly, glycosaminoglycans can effectively stabilize the etching rate of copper, thereby controlling the decomposition of hydrogen peroxide by copper ions and stabilizing the pH of the etching solution, making the etching reaction safer. Simultaneously, functional groups such as -OH and -NH2 are protonated under acidic conditions, and these protonated cations can be adsorbed at the interface between the metal and the etching solution, thus playing a role in metal corrosion inhibition.

[0057] Secondly, glycosaminoglycans form a helical structure in copper acid etching solution. The negatively charged groups on their surface are arranged in a "pocket" shape, which can perfectly adapt to copper ions. Furthermore, the flexible sugar chains can adjust and optimize the chelate coordination environment of copper ions at any time through conformation, so as to be more stable.

[0058] Thirdly, the core groups of chondroitin sulfate, as a preferred choice, include acetamino and sulfate ester groups. These groups collectively endow chondroitin sulfate with hydrophilicity, strong negative charge, and good stability. The multi-anionic nature of chondroitin sulfate can attract metal ions through electrostatic interactions. On the other hand, the oxygen (-OSO3-) of the sulfate ester group acts as an electron donor, forming coordinate bonds with the empty orbitals of metal ions, thereby anchoring free metal ions. Simultaneously, with the synergy of organic acids, the organic acids dissolve copper, which is then oxidized by hydrogen peroxide to divalent copper ions, which are then chelated by chondroitin sulfate, achieving a further increase in the ppm of dissolved copper without the precipitation of crystal products. Furthermore, the sulfate ester groups in chondroitin sulfate also enhance the chelation of metallic copper.

[0059] [Second Technical Solution]

[0060] A method for preparing the above-mentioned copper etching solution for display panels that resists galvanic corrosion includes the following steps:

[0061] Weigh out the respective amounts of each component, mix and stir evenly, and filter to obtain a copper etching solution resistant to galvanic corrosion.

[0062] [The third technical solution]

[0063] A method for using the aforementioned copper etching solution for display panels that resists galvanic corrosion includes the following steps:

[0064] Step 1: Immerse the glass substrate in the above etching solution and etch it at a certain temperature; the etching temperature is, for example, raised to 20-40℃ for etching, and the etching time is adjusted according to the etching thickness, for example, 60s-90s for 2500Å etching and 100-130s for 5000Å etching.

[0065] Step 2: Rinse the etched glass substrate in ultrapure water for 20-30 seconds, and then dry it with nitrogen.

[0066] [Fourth technical solution]

[0067] The use of the aforementioned copper etchant for display panels, which is resistant to galvanic corrosion, in glass substrate etching.

[0068] This invention provides a copper etching solution for display panels that resists galvanic corrosion, its preparation method, and its application, which have the following beneficial effects:

[0069] 1. The formulation of this invention constitutes a single-agent copper acid etching solution based on a high-hydrogen peroxide system. The selected metal rate control agent can play a dual role in corrosion inhibition and metal chelation, regulating the dissolution rate of Cu and MoNiTi. Simultaneously, the -OH and -NH2 functional groups can form an adsorption film on the Cu surface, inhibiting the etching rate of Cu, balancing the etching rate difference between Cu and MoNiTi, controlling the galvanic cell reaction, ensuring simultaneous etching of multiple layers, and improving the etching precision of the etching solution. No white crystals precipitate in the etching solution as the copper ppm increases.

[0070] 2. This high-hydrogen peroxide system, a single-agent copper acid etching solution, can ensure that when the continuous copper dissolution reaches 6000ppm, the metal rate control agent can chelate the initially generated divalent copper, thereby preventing the formation of monovalent copper as a byproduct. As the copper ppm increases, the color of the etching solution will not change from blue to green, maintaining the stability of the etching rate.

[0071] 3. This high-hydrogen peroxide system single-agent copper acid etching solution is compatible with Cu / MTD alloy substrates (Cu layer thickness range of 5500 Å, MTD (MoNiTi) thickness of 300 Å) and (2500 Å, MTD (MoNiTi) thickness of 300 Å), and can take into account issues such as Cu / MTD etching rate ratio, morphology, two-stage corner, and internal cutting.

[0072] Therefore, the etching solution of the present invention has very good application prospects and potential for large-scale industrial promotion in the field of display panel etching. Attached Figure Description

[0073] Figure 1 : A 40,000x magnified SEM image of a glass substrate etched with the etching solution of Example 1 after a film thickness of 5500 Å and a Cu / MTD of 500 ppm.

[0074] Figure 2 : A 40,000x magnified SEM image of a glass substrate etched with the etching solution of Example 1 after a film thickness of 5500 Å and a Cu / MTD of 6000 ppm.

[0075] Figure 3 : A 40,000x magnified SEM image of a glass substrate with a 5500 Å film thickness and 6000 ppm Cu / MTD after etching with the etching solution of Comparative Example 1.

[0076] Figure 4 : A 40,000x SEM image of a glass substrate etched with the etching solution of Example 1 after a 2500 Å film thickness and 500 ppm Cu / MTD.

[0077] Figure 5: A 40,000x SEM image of a glass substrate with a film thickness of 5500 Å and a Cu / MTD of 500 ppm, etched using the etching solution of Comparative Example 1. Detailed Implementation

[0078] The present invention will be further described below with reference to specific embodiments and accompanying drawings:

[0079] In this invention, Examples 1-7 and Comparative Examples 1-3 disclose various etching solutions, the components and mass ratios of which are shown in Tables 1 and 2.

[0080] Table 1. Components and proportions of copper etching solutions for galvanic corrosion resistant used in display panels, Examples 1-7.

[0081] Table 2. Components and proportions of etching solutions for Comparative Examples 1-3

[0082] The preparation method of the copper etching solution for display panels resisting galvanic corrosion according to the present invention is as follows:

[0083] Weigh out the respective amounts of each component, mix and stir well, and then filter.

[0084] Method of using the copper etching solution for display panels that resists galvanic corrosion according to the present invention:

[0085] Step 1: Immerse the glass substrate in the above etching solution and heat it to 20-40℃. The etching time is adjusted according to the etching thickness. For example, 60s-90s for 2500Å etching and 100-130s for 5000Å etching.

[0086] Step 2: Rinse the etched glass substrate in ultrapure water for 20-30 seconds, and then dry it with nitrogen.

[0087] Regarding performance testing and explanation:

[0088] Performance 1: Etching morphology, incision, and CDLoss test methods for one side.

[0089] The Cu / MTD glass substrate was immersed in the prepared etching solution, and the etching reaction temperature was controlled at 30℃. A long-term copper dissolution test was conducted (500-6000 ppm), increasing the copper content by 500 ppm per hour. After each stage, the copper powder was completely dissolved. Glass substrates of different film thicknesses were then immersed in the etching solution at 30℃ for further reaction, and the presence of white solid precipitation was observed at each stage of copper dissolution. After the entire reaction was completed, the etched glass substrates were sent for SEM examination to observe the etching characteristics, morphology, presence of internal cutting, and CDLoss (single-sided).

[0090] Performance 2: Test method for corrosion rate:

[0091] First, the etching rate of pure copper (Cu) is calculated, and then the composite metal film is etched. Then, the etching rate of the metal is calculated by dividing the pure copper film and the metal film by the etching time (the time it takes for the metal film to be etched through) minus the number of multilayer metal films.

[0092] The performance test results of the etching solutions obtained in Examples 1-7 and Comparative Examples 1-3 are shown in Table 3.

[0093] Table 3 Test Data

[0094] Analysis and explanation of the test results:

[0095] As can be seen from the test data in Table 3, compared with Example 1, Comparative Example 1 lacks a metal rate control agent, which leads to the inability to control the galvanic cell reaction between Cu / MTD metals, making it difficult to control the Cu / MTD etching rate ratio and resulting in obvious incision phenomenon.

[0096] Comparative Example 2 uses sodium chondroitin sulfate as a metal rate control agent. The introduction of sodium salt into the etching solution increases the ionic strength, changes the double layer structure, and thus affects the adsorption and transport process of reactants on the copper surface. In addition, sodium ions have high mobility and can easily migrate to the insulating layer under an electric field, leading to electrochemical migration and ultimately causing a short circuit in the panel.

[0097] Comparative Example 3 uses arabinosyl xylan as a metal rate control agent. Because its structure contains only a single hydroxyl group and does not contain acetamino or sulfate groups, its ability to control metallic copper is not strong. In the later stages, the etching rate increases with the higher the copper ppm, and the morphology after etching is poor with obvious incision.

[0098] Further comparison can be made using the accompanying diagrams in the instruction manual:

[0099] Figure 1 A 40,000x magnified SEM image of a glass substrate etched with the etching solution of Example 1 after a film thickness of 5500 Å and a Cu / MTD of 500 ppm. Figure 2 A 40,000x magnified SEM image of a glass substrate etched with the etching solution of Example 1 after a film thickness of 5500 Å and a Cu / MTD of 6000 ppm. Figure 3 This is a 40,000x magnified SEM image of a glass substrate after etching a Cu / MTD film with a thickness of 6000ppm and a film thickness of 5500Å, for Comparative Example 1. Figure 4 A 40,000x magnified SEM image of a glass substrate after etching with the etching solution of Example 1 for a 2500 Å film thickness and 500 ppm Cu / MoTD. Figure 5The image is a 40,000x SEM image of a glass substrate with a 5500 Å film thickness and 500 ppm Cu / MTD, etched using the etching solution of Comparative Example 1.

[0100] from Figure 1 It can be seen that there are no two-segment corners or Mo tails after etching, indicating that the etching effect is good.

[0101] from Figure 2 It can be seen that there are no two-segment corners or Mo tails after etching, indicating that the etching effect is good.

[0102] from Figure 3 It can be seen that the glass substrate after etching has obvious incision.

[0103] from Figure 4 It can be seen that the etched morphology is good.

[0104] from Figure 5 As can be seen from the image, the etching rate of the MTD substrate is too fast, resulting in obvious incision.

[0105] The present invention has been described above by way of example with reference to the embodiments and accompanying drawings. Obviously, the implementation of the present invention is not limited to the above-described manner. Any improvements made by adopting the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A copper etching solution for display panels that resists galvanic corrosion, characterized in that, Based on parts by weight, it includes the following components: 20-30 parts hydrogen peroxide; Inorganic salts 0.5-3 parts; 1-10 parts organic acids; Inorganic acid 0.5-3 parts; 5-15 parts of surfactant; Metal rate control agent 1-15 parts; Corrosion inhibitor 0.1-2 parts; 40-70 parts deionized water; The metal rate control agent is a glycosaminoglycan.

2. The copper etching solution for display panels against galvanic corrosion according to claim 1, characterized in that: The metal rate control agent is one or more of chondroitin sulfate, hyaluronic acid, and keratin sulfate.

3. The copper etching solution for display panels against galvanic corrosion according to claim 1, characterized in that: The inorganic salt is one or more of potassium sulfate, sodium chloride, potassium chloride, potassium nitrate, ammonium nitrate, sodium nitrate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate.

4. The copper etching solution for display panels against galvanic corrosion according to claim 1, characterized in that: The organic acid is one or more of the following: mandelic acid, malic acid, citric acid, tartaric acid, malonic acid, fumaric acid, maleic acid, formic acid, succinic acid, and iminodisuccinic acid.

5. The copper etching solution for display panels against galvanic corrosion according to claim 1, characterized in that: The inorganic acid is one or more of sulfuric acid, phosphoric acid, boric acid, and nitric acid.

6. The copper etching solution for display panels against galvanic corrosion according to claim 1, characterized in that: The surfactant is a short-chain alcohol.

7. The copper etching solution for display panels against galvanic corrosion according to claim 1, characterized in that: The corrosion inhibitor is one or more of 3-aminotriazole, benzotriazole, 5-aminotetrazole, 6-nitrobenzimidazole, 2-aminothiazole, 4-aminotetrazole, and 3-amino-1,2,4-triazole.

8. A method for preparing a copper etching solution for display panels resistant to galvanic corrosion according to any one of claims 1-7, characterized in that, Includes the following steps: Weigh out the respective amounts of each component, mix and stir evenly, and filter to obtain a copper etching solution resistant to galvanic corrosion.

9. A method of using the copper etching solution for display panels with anti-galvanic corrosion as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Immerse the glass substrate in the above etching solution and etch it at a certain temperature; Step 2: Rinse the etched glass substrate in ultrapure water and then dry it with nitrogen.

10. Use of the copper etchant for display panels according to any one of claims 1-7 in glass substrate etching.

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