High etching rate selective etching solution and its preparation method and application

Abstract

The application discloses a high-etching-rate selective etching liquid and a preparation method and application thereof, and comprises the following components in parts by mass: 5-10 parts of organic acid, 60-80 parts of inorganic acid, 8-15 parts of oxidizing agent, 1-2 parts of nitrate, 1-2 parts of additive, and 5-15 parts of pure water; the nitrate comprises at least one of sodium nitrate, potassium nitrate, calcium nitrate and ammonium nitrate; and the additive is an organic sulfide substance. The etching liquid is clear and colorless, has high etching rate and high selectivity, is simple to prepare, has good etching uniformity, and can be applied in the field of etching semiconductor display panel manufacturing, and mainly solves the problem of serious shrinkage of upper metal (Al and Mo layers) after etching of a Mo / Al / Ti substrate.

Description

Technical Field

[0001] This invention belongs to the field of electronic chemicals technology, and in particular relates to an etching solution with a high etching rate selectivity, its preparation method, and its application. Background Technology

[0002] As a core component of the modern electronics industry, the semiconductor display panel industry plays a crucial role in converting electrical signals into visible images, and is widely used in numerous fields such as smartphones, tablets, automotive displays, televisions, and wearable devices. With the widespread adoption of consumer electronics globally, the rapid development of internet and communication technologies, and the accelerated penetration of artificial intelligence, human demand for information interaction is growing daily, and the semiconductor display panel industry has ushered in unprecedented development opportunities.

[0003] In recent years, the display panel industry has shown promising development prospects in terms of market size, technological innovation, and application expansion. The rapid rise of OLED technology, the continuous optimization of LCD technology, the emergence of Mini / Micro and quantum dot technologies, and the integrated application of emerging industrial technologies such as AI have all injected new vitality into the industry. Therefore, display panel manufacturing technology has become increasingly important in the panel industry in recent years.

[0004] Taking TFT-LCD as an example, it is well known that the manufacturing process of TFT-LCD mainly involves three stages: the front-end array, the middle-end cell, and the back-end module assembly. The front-end array is the most crucial, comprising four main parts: film formation, photoresist coating, etching, and photoresist removal. The etching solution, as the medium for the etching process, directly affects the subsequent cell and module assembly processes, ultimately impacting the TFT-LCD's imaging performance. Therefore, domestic wet etching technology has undergone continuous reform and development in recent years. On the other hand, the demand for panel etching solutions from domestic panel manufacturers has shown a steady upward trend in recent years, and market demand is constantly expanding.

[0005] Chinese patent CN115948746A discloses an Al / Mo etching solution, its preparation method, and its application. The patent states that the prepared solution may appear light blue, which does not meet the general requirement that etching solutions should be clear and colorless. Furthermore, it cannot guarantee that the TFT-array will not have any color residue after etching, and whether this color residue will affect subsequent processes. Summary of the Invention

[0006] The main technical problem solved by this invention is to provide an etching solution with a high etching rate selectivity, its preparation method and application. The etching solution is clear and colorless, with a fast etching rate, high selectivity, simple preparation method and good etching uniformity. The etching solution can be applied in the field of etching semiconductor display panel manufacturing, and mainly solves the problem of severe shrinkage of the upper metal (Al&Mo layer) after etching of Mo / Al / Ti substrate.

[0007] To solve the above-mentioned technical problems, the present invention adopts a technical solution as follows: a high etching rate selectivity etching solution, which, by mass parts, comprises the following components: 5-10 parts of organic acid, 60-80 parts of inorganic acid, 8-15 parts of oxidant, 1-2 parts of nitrate, 1-2 parts of additive, and 5-15 parts of pure water. The nitrate includes at least one of sodium nitrate, potassium nitrate, calcium nitrate, and ammonium nitrate; Preferably, the nitrate is potassium nitrate. Potassium nitrate provides nitrate ions to the etching solution, playing an auxiliary oxidation role, and also acts as a corrosion inhibitor for the Mo and Al metal layers. The principle is as follows: a) As a corrosion inhibitor, potassium nitrate inhibits the redox reaction caused by charge accumulation by adjusting the double-layer structure of the metal-solution interface. That is, when potassium nitrate is adsorbed on the Al and Mo surfaces, it changes the charge distribution and reduces the difference in electrode potentials, thereby reducing the risk of excessive etching of Al and Mo metals. b) Potassium nitrate molecules cover the Al and Mo metal surfaces through physical or chemical adsorption, forming a dense oxide film that isolates the etching solution medium from direct contact with the Al and Mo metal layers. The additive is an organic sulfide.

[0008] Furthermore, the additive includes at least one of tributyl sulfide (TBBS), dimethyl disulfide (DMDS), benzyl sulfide, thiophenol, methanethiol, dodecyl mercaptan, and 2-mercaptoethanol.

[0009] Preferably, the additive shown is 2-mercaptoethanol. 2-mercaptoethanol, as an additive, is soluble in the etching solution system and exists stably within the system. When potassium nitrate is used in combination with 2-mercaptoethanol, the protective effect is enhanced. The principle is that organic sulfides further strengthen the protective barrier of the metal surface by generating insoluble compounds, thus achieving a synergistic corrosion inhibition effect with potassium nitrate.

[0010] Preferably, a high etching rate selectivity etching solution comprises, by mass, the following components: 8 parts organic acid, 70 parts inorganic acid, 10 parts oxidant, 1.5 parts nitrate, 1 part additive, and 9.5 parts pure water.

[0011] Furthermore, the organic acid includes at least one selected from oxalic acid, acetic acid, succinic acid, citric acid, and tartaric acid. Preferably, the organic acid is acetic acid, which provides hydrogen ions to the weak acid system and has a certain buffering effect. On the other hand, acetic acid also acts as a diluent in the system.

[0012] Furthermore, the inorganic acid includes at least one of hydrochloric acid, phosphoric acid, hypochlorous acid, concentrated sulfuric acid, permanganic acid, hydrofluoric acid, hydroiodic acid, and hydrobromic acid; Preferably, the inorganic acid includes hydrochloric acid and concentrated sulfuric acid.

[0013] Hydrochloric acid provides hydrogen ions to the etching solution and creates an acidic environment for the system. On the other hand, it chelates the Al, Mo, and Ti ions in the etched system.

[0014] Concentrated sulfuric acid primarily etches Mo, Al, and Ti metals, converting metal oxides into ionic forms within the etching solution.

[0015] Furthermore, the oxidant includes at least one of hydrogen peroxide, nitric acid, perchloric acid, and hypochlorous acid; Preferably, the oxidant is hydrogen peroxide. Hydrogen peroxide is the oxidant in the system, and its main function is to oxidize metals Al, Mo, and Ti into their corresponding oxides. At the same time, it also provides hydrogen ions to the system.

[0016] The present invention also provides a method for preparing an etchant with a high etch rate selectivity ratio, comprising the following steps: Step 1: Weigh out the respective amounts of each component; Step 2: At room temperature, add pure water, organic acid and inorganic acid to the container and stir. Turn on the refrigeration system and slowly add the inorganic acid to avoid excessive volatilization of components due to excessive system temperature. Continue adding materials after the inorganic acid has finished releasing heat. Step 3: Add the oxidant to the container at room temperature and stir. Finally, add the nitrate and additives to the container and stir thoroughly until the solution is clear and free of particles.

[0017] As a preferred method for preparing etching solution, the following steps are included: Step 1: Weigh out the respective amounts of each component; Step 2: At room temperature, add pure water, acetic acid and hydrochloric acid to the container and stir. Turn on the refrigeration system and slowly add concentrated sulfuric acid to avoid excessive evaporation of components due to excessive system temperature. Continue adding materials after the concentrated sulfuric acid has finished releasing heat. Step 3: Add hydrogen peroxide to the container at room temperature and stir. Finally, add potassium nitrate and 2-mercaptoethanol to the container and stir thoroughly until the solution is clear and free of particles.

[0018] Application of a high etch rate selectivity etchant in one-step etching of Mo / Al / Ti substrates.

[0019] The present invention also provides a one-step etching method for etching Mo / Al / Ti substrates using an etchant with a high etch rate selectivity ratio, comprising the following steps: S1: heating the etchant to a temperature range of 30-40°C, and after the temperature stabilizes, completely immersing the Mo / Al / Ti substrate (thickness specifications of 300Å / 2500Å / 2000Å) in the etchant, and starting to continuously agitate the substrate, with an etching time of 80-100s recommended; S2: Rinse the Mo / Al / Ti substrate with flowing pure water for at least 30 seconds to ensure that there is no etching solution or other residue on the substrate surface. Finally, blow it dry with nitrogen to obtain the etched Mo / Al / Ti substrate.

[0020] The beneficial effects of the present invention include at least the following: The etching solution of the present invention is clear and colorless, simple to produce, low in cost, and has low evaporation loss. After etching, it can be rinsed with pure water only, and is non-toxic to the environment and human body. The etching solution of this invention has a high selectivity for etching and a fast etching rate, which improves the industrial production capacity per unit time. The etching solution of the present invention uses potassium nitrate and 2-mercaptoethanol to slow down the etching rate of the Mo / Al layer metal during the etching process, thereby avoiding the phenomenon that excessive inward shrinkage of the Mo / Al layer metal after etching leads to poor overall substrate morphology. The etching solution of the present invention has low viscosity and good fluidity, which can uniformly etch all parts of the substrate, including the substrate edge. After etching, the etching effect of all parts and edges of the substrate is consistent after SEM inspection. Attached Figure Description

[0021] Appendix Figure 1 This is a SEM cross-sectional image of the substrate AA region unit after etching in Example 2, without removal of photoresist. SEM magnification: 40000x. Appendix Figure 2 This is a SEM cross-sectional image of the substrate AA region unit after etching in Example 2, with SEM magnification of 40,000 times. Appendix Figure 3 This is a SEM cross-sectional image of the substrate AA region unit after etching in Example 1, without removal of photoresist. SEM magnification: 40,000x. Appendix Figure 4 This is a SEM cross-sectional image of the substrate AA region unit after etching in Example 1, with SEM magnification of 40,000 times. Appendix Figure 5 This is a map showing the distribution of CD-Loss measurement points. Detailed Implementation

[0022] The preferred embodiments of the present invention will now be described in detail so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0023] Example: A high etch rate selectivity etching solution, by mass, comprises the following components: 5-10 parts organic acid, 60-80 parts inorganic acid, 8-15 parts oxidant, 1-2 parts nitrate, 1-2 parts additive, and 5-15 parts pure water. The nitrate includes at least one of sodium nitrate, potassium nitrate, calcium nitrate, and ammonium nitrate; Preferably, the nitrate is potassium nitrate. Potassium nitrate provides nitrate ions to the etching solution, playing an auxiliary oxidation role, and also acts as a corrosion inhibitor for the Mo and Al metal layers. The principle is as follows: a) As a corrosion inhibitor, potassium nitrate inhibits the redox reaction caused by charge accumulation by adjusting the double-layer structure of the metal-solution interface. That is, when potassium nitrate is adsorbed on the Al and Mo surfaces, it changes the charge distribution and reduces the difference in electrode potentials, thereby reducing the risk of excessive etching of Al and Mo metals. b) Potassium nitrate molecules cover the Al and Mo metal surfaces through physical or chemical adsorption, forming a dense oxide film that isolates the etching solution medium from direct contact with the Al and Mo metal layers. The additive is an organic sulfide.

[0024] The additives include at least one of tributyl sulfide (TBBS), dimethyl disulfide (DMDS), benzyl sulfide, thiophenol, methanethiol, dodecyl mercaptan, and 2-mercaptoethanol.

[0025] Preferably, the additive shown is 2-mercaptoethanol. 2-mercaptoethanol, as an additive, is soluble in the etching solution system and exists stably within the system. When potassium nitrate is used in combination with 2-mercaptoethanol, the protective effect is enhanced. The principle is that organic sulfides further strengthen the protective barrier of the metal surface by generating insoluble compounds, thus achieving a synergistic corrosion inhibition effect with potassium nitrate.

[0026] Preferably, a high etching rate selectivity etching solution comprises, by mass, the following components: 8 parts organic acid, 70 parts inorganic acid, 10 parts oxidant, 1.5 parts nitrate, 1 part additive, and 9.5 parts pure water.

[0027] The organic acid includes at least one selected from oxalic acid, acetic acid, succinic acid, citric acid, and tartaric acid. Preferably, the organic acid is acetic acid, which provides hydrogen ions to the weak acid system and has a certain buffering effect. On the other hand, acetic acid also acts as a diluent in the system.

[0028] The inorganic acid includes at least one of hydrochloric acid, phosphoric acid, hypochlorous acid, concentrated sulfuric acid, permanganic acid, hydrofluoric acid, hydroiodic acid, and hydrobromic acid. Preferably, the inorganic acid includes hydrochloric acid and concentrated sulfuric acid.

[0029] Hydrochloric acid provides hydrogen ions to the etching solution and creates an acidic environment for the system. On the other hand, it chelates the Al, Mo, and Ti ions in the etched system.

[0030] Concentrated sulfuric acid primarily etches Mo, Al, and Ti metals, converting metal oxides into ionic forms within the etching solution.

[0031] The oxidant includes at least one of hydrogen peroxide, nitric acid, perchloric acid, and hypochlorous acid; Preferably, the oxidant is hydrogen peroxide. Hydrogen peroxide is the oxidant in the system, and its main function is to oxidize metals Al, Mo, and Ti into their corresponding oxides. At the same time, it also provides hydrogen ions to the system.

[0032] The present invention also provides a method for preparing an etchant with a high etch rate selectivity ratio, comprising the following steps: Step 1: Weigh out the respective amounts of each component; Step 2: At room temperature, add pure water, organic acid and inorganic acid to the container and stir. Turn on the refrigeration system and slowly add the inorganic acid to avoid excessive volatilization of components due to excessive system temperature. Continue adding materials after the inorganic acid has finished releasing heat. Step 3: Add the oxidant to the container at room temperature and stir. Finally, add the nitrate and additives to the container and stir thoroughly until the solution is clear and free of particles.

[0033] As a preferred method for preparing etching solution, the following steps are included: Step 1: Weigh out the respective amounts of each component; Step 2: At room temperature, add pure water, acetic acid and hydrochloric acid to the container and stir. Turn on the refrigeration system and slowly add concentrated sulfuric acid to avoid excessive evaporation of components due to excessive system temperature. Continue adding materials after the concentrated sulfuric acid has finished releasing heat. Step 3: Add hydrogen peroxide to the container at room temperature and stir. Finally, add potassium nitrate and 2-mercaptoethanol to the container and stir thoroughly until the solution is clear and free of particles.

[0034] Application of a high etch rate selectivity etchant in one-step etching of Mo / Al / Ti substrates.

[0035] The present invention also provides a one-step etching method for etching Mo / Al / Ti substrates using an etchant with a high etch rate selectivity ratio, comprising the following steps: S1: heating the etchant to a temperature range of 30-40°C, and after the temperature stabilizes, completely immersing the Mo / Al / Ti substrate (thickness specifications of 300Å / 2500Å / 2000Å) in the etchant, and starting to continuously agitate the substrate, with an etching time of 80-100s recommended; S2: Rinse the Mo / Al / Ti substrate with flowing pure water for at least 30 seconds to ensure that there is no etching solution or other residue on the substrate surface. Finally, blow it dry with nitrogen to obtain the etched Mo / Al / Ti substrate.

[0036] Specific implementation examples: Table 1 Examples 1-4

[0037] Table 2 Comparative Examples 1-3

[0038] Table 3 Test Results

[0039] The performance indicators and their ranges corresponding to the innovations of the cleaning fluid of this invention are shown in the table below.

[0040] in: The performance 1 etching rate test method is as follows: The etching solution was heated to 35°C, and substrates with thicknesses of 3000 Å pure Mo, 3000 Å pure Al, and 3000 Å pure Ti were etched for 10 s each. After etching, the substrates were rinsed with pure water and dried with nitrogen. The film thickness loss of substrates with different thicknesses was measured using SEM, and the different etching rates were compared. The experimental results are shown in the table below. Table of Experimental Results for Traditional Etching Solutions (Phosphoric Acid, Acetic Acid, and Nitric Acid System Etching Solutions)

[0041] Table of Etching Solution Experiment Results for This Method (Example 1)

[0042] in conclusion: 1. Based on the data, the etching rate of the etching solution in this method is higher than that of the traditional etching solution, meaning that the unit production capacity is greater.

[0043] 2. The etching rate of the Al / Mo layer metal in this method is smaller than that of the Ti layer than that of traditional etching solutions, which provides a basis for the fact that the etching solution of this method can improve the morphological problem of severe shrinkage of the Al / Mo layer metal.

[0044] The morphology testing method for the Al / Mo layer after etching is as follows: The experiment was conducted using a one-step etching method for Mo / Al / Ti substrates (etching temperature 35℃, time 80s). The etching solutions used were those from Examples 1 and 2, respectively, to obtain the etched Mo / Al / Ti substrates. The etched Mo / Al / Ti substrates were sliced ​​and their morphology was analyzed using SEM. The experimental results are as follows: Figure 1 , 2 3, 4.

[0045] in conclusion: The substrate Mo / Al layer metal etched using the etching solution of this method did not exhibit severe shrinkage problems, while traditional etching solutions caused severe shrinkage morphology problems in the Mo / Al layer metal due to the large difference in etching rates among the three metals.

[0046] The test method for performance uniformity is as follows: An experimental procedure was performed using a one-step etching method for Mo / Al / Ti substrates (etching temperature 35℃, time 80s) to obtain the etched Mo / Al / Ti substrates. The etched Mo / Al / Ti substrates were sliced, and CD-Loss values ​​at different locations on the substrate were recorded using SEM for comparison (e.g., ...). Figure 5 As shown in the diagram, the CD-Loss measurement points are distributed. The experimental results are shown in the table below: Table of Experimental Results for Traditional Etching Solutions (Phosphoric Acid, Acetic Acid, and Nitric Acid System Etching Solutions)

[0047] Table of Etching Solution Experiment Results for This Method (Example 1)

[0048] Conclusion: Based on the experimental data, the CD-Loss phase difference at various points on the substrate after etching with the proposed method is smaller than that after etching with the traditional etching solution. Therefore, the etching solution of the proposed method exhibits better uniformity than the traditional etching solution.

[0049] The above are merely embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural transformations made using the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. An etchant with a high etch rate selectivity, characterized in that: By weight, it includes the following components: 5-10 parts organic acid, 60-80 parts inorganic acid, 8-15 parts oxidant, 1-2 parts nitrate, 1-2 parts additive, and 5-15 parts pure water. The nitrate includes at least one of sodium nitrate, potassium nitrate, calcium nitrate, and ammonium nitrate; The additive is an organic sulfide.

2. The high etch rate selectivity etchant according to claim 1, characterized in that: The additives include at least one of tributyl sulfide, dimethyl disulfide, benzyl sulfide, thiophenol, methanethiol, dodecyl mercaptan, and 2-mercaptoethanol.

3. The high etch rate selectivity etchant according to claim 2, characterized in that: The additive shown is 2-mercaptoethanol.

4. The high etch rate selectivity etchant according to claim 1, characterized in that: By weight, it includes the following components: 8 parts organic acid, 70 parts inorganic acid, 10 parts oxidant, 1.5 parts nitrate, 1 part additive, and 9.5 parts pure water.

5. The high etch rate selectivity etchant according to claim 1, characterized in that: The organic acid includes at least one of oxalic acid, acetic acid, succinic acid, citric acid, and tartaric acid.

6. The high etch rate selectivity etchant according to claim 1, characterized in that: The inorganic acid includes at least one of hydrochloric acid, phosphoric acid, hypochlorous acid, concentrated sulfuric acid, permanganic acid, hydrofluoric acid, hydroiodic acid, and hydrobromic acid.

7. The high etch rate selectivity etchant according to claim 1, characterized in that: The oxidant includes at least one of hydrogen peroxide, nitric acid, perchloric acid, and hypochlorous acid.

8. A method for preparing a high etch rate selectivity etchant according to any one of claims 1-7, characterized in that: Includes the following steps: Step 1: Weigh out the respective amounts of each component; Step 2: At room temperature, add pure water, organic acid and inorganic acid to the container and stir. Turn on the refrigeration system and slowly add the inorganic acid to avoid excessive volatilization of components due to excessive system temperature. Continue adding materials after the inorganic acid has finished releasing heat. Step 3: Add the oxidant to the container at room temperature and stir. Finally, add the nitrate and additives to the container and stir thoroughly until the solution is clear and free of particles.

9. The use of a high etch rate selectivity etchant according to any one of claims 1-7 in one-step etching of Mo / Al / Ti substrates.

10. An etching method for a one-step etching of a Mo / Al / Ti substrate using a high etch rate selectivity etchant according to any one of claims 1-7, characterized in that: The process includes the following steps: S1: Heat the etching solution to a temperature range of 30-40℃. After the temperature stabilizes, completely immerse the Mo / Al / Ti substrate in the etching solution and start continuously agitating the substrate. The etching time is recommended to be 80-100 seconds. S2: Rinse the Mo / Al / Ti substrate with flowing pure water for at least 30 seconds to ensure that there is no etching solution or other residue on the substrate surface. Finally, blow it dry with nitrogen to obtain the etched Mo / Al / Ti substrate.

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