Using method of TFT metal film etching liquid

Abstract

The invention belongs to the technical field of metal film etching solutions, and particularly relates to a use method of a TFT (Thin Film Transistor) metal film etching solution, which comprises the following steps of: 1, forming a copper metal film on a substrate through a thin film deposition technology; 2, coating photoresist on the copper-based metal film through a spin coating, spraying or dipping method, then exposing the photoresist through a specific light source, and putting the exposed substrate into a developing solution for developing treatment; and 3, preparing an etching solution, and putting the developed substrate into the etching solution for etching treatment. According to the invention, the etching cost can be reduced and an excellent etching effect can be ensured by optimizing the component proportion in the etching solution, selecting proper component compounds and cooperatively using a proper using method.

Description

Technical Field

[0001] The invention belongs to the technical field of metal film etching liquid, and in particular relates to a method for using a TFT metal film etching liquid. Background Art

[0002] Etching is a technique that removes materials by chemical reaction or physical impact. Etching technology is divided into wet etching and dry etching, among which wet etching uses chemical reagents to achieve the purpose of etching through chemical reaction. In recent years, while the demand for liquid crystal displays has continued to increase, people have also put forward higher requirements for product quality and picture accuracy. The effect of etching can directly affect the quality of panel manufacturing process and the accuracy and quality of high-density fine wire images. In the past, aluminum or aluminum alloys were used in the metal wiring of liquid crystal display devices, but with the large-scale and high-resolution of liquid crystal displays, the gate lines and data lines connected to thin-film transistors will become longer, and the resistance of these wirings will also increase, thus causing problems such as signal delay. Therefore, research has turned to materials with lower resistance, namely copper or wiring combinations with copper as the main component.

[0003] Molybdenum and titanium have the advantages of high adhesion to substrates such as glass, difficulty in diffusing into silicon semiconductor films, and having barrier properties. Therefore, a stacked film containing copper, copper-molybdenum / copper-titanium alloys with copper as the main component, etc. is formed on a substrate such as glass by a film forming process such as sputtering, and then an electrode pattern is formed by an etching process using a resist as a mask.

[0004] Fluoroic acid additives are often used to improve the etching performance of etching solutions for copper / molybdenum and copper / molybdenum-niobium alloy laminated films. However, fluoric acid additives have difficulties in wastewater treatment. If fluoric acid additives are not used, a large amount of residue will be generated during the etching process, resulting in process short circuits and contamination Mura problems. Therefore, it is very necessary to develop a metal film etching solution that does not contain fluorine compounds and can improve etching performance. Summary of the invention

[0005] In order to solve the deficiencies in the prior art, the present invention provides a method for using a TFT metal film etching solution, which can reduce etching costs and ensure excellent etching effects by optimizing the component ratio in the etching solution and selecting suitable component compounds in combination with appropriate use methods.

[0006] The present invention adopts the following technical solution:

[0007] A method for using a TFT metal film etching solution comprises the following steps:

[0008] Step 1: forming a copper-based metal film on a substrate by thin film deposition technology;

[0009] Step 2: coating the photoresist on the copper-based metal film by spin coating, spray coating or dipping, then exposing the photoresist by a specific light source, and placing the exposed substrate in a developer for development;

[0010] Step 3: Prepare etching solution and place the developed substrate into the etching solution for etching.

[0011] Furthermore, the thin film deposition technology in step 1 includes any one of physical vapor deposition technology and chemical vapor deposition technology.

[0012] Furthermore, in step 1, the copper-based metal film is a copper / molybdenum metal film or a copper / molybdenum-niobium alloy metal film.

[0013] Furthermore, the coating of the photoresist on the copper-based metal film in step 2 includes the following steps: firstly removing impurities from the substrate, then coating the photoresist on the copper-based metal film, and finally baking at 80-120° C. for 5-15 minutes to solidify the photoresist.

[0014] Furthermore, the etching solution in step three includes the following components: metal oxidant, organic acid, organic base, corrosion inhibitor and deionized water.

[0015] Furthermore, the preparation of the etching solution in step three includes the following steps: S1. Weighing each component according to the weight ratio; S2. Stirring and mixing the organic acid, corrosion inhibitor and deionized water until all materials are completely dissolved; S3. Adding the organic base while maintaining stirring, adding the metal film oxidant after the solution is cooled to room temperature, and continuing to stir until the mixture is completely mixed.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1) In the process of using the etching solution, the present invention first adopts the step-by-step dissolution step to prepare the etching solution, which ensures that the components of the etching solution can be fully mixed and avoids violent reactions between the components, thereby improving production safety. In specific use, the present invention cooperates with thin film deposition technology, exposure and development to quickly etch copper metal films and molybdenum alloy metal films, reduce chamfers and CD loss, and improve etching effects.

[0018] 2) The etching solution prepared in the present invention does not contain fluorine compounds, and will not cause environmental pollution during the production process. In addition, the wastewater generated during the production process does not contain fluorine compounds, which can be better treated and reduce production costs. At the same time, the absence of fluorine compounds can reduce the residues in the etching process, reduce the process short circuit and contamination mura problems caused by etching.

[0019] 3) Compared with the existing etching solution, the etching solution prepared in the present invention can etch the copper / molybdenum alloy double-layer film at the same time by selecting suitable oxidants and organic acids and bases and optimizing their ratios. Compared with the existing etching solution, it can increase the etching rate, reduce the etching cost and ensure excellent etching effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of etching of the present invention;

[0021] Figure 2 This is a scanning electron microscope image of a substrate after being etched by the etching solution prepared in Example 1 of the present invention;

[0022] Figure 3 This is a scanning electron microscope image of a substrate after etching with the etching solution prepared in Example 1 of the present invention.

[0023] Description of the reference numerals: photoresist 1, copper layer 2, molybdenum / molybdenum alloy layer 3, substrate 4, side etching 5, taper angle 6. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only part of the embodiments of the present invention, not all of them. Based on the spirit of the present invention, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the present invention.

[0025] Metal oxidants

[0026] The etching solution of the present invention uses hydrogen peroxide solution as the metal oxidant, but is not limited to hydrogen peroxide solution, and may also include one or more combinations of peracetic acid and persulfate.

[0027] Organic Acid

[0028] The organic acid in the present invention not only has the function of regulating the etching rate, but also has the function of regulating the pH value of the etching composition and improving the storage stability. The organic acid in the present invention comprises one or a combination of peracetic acid, perbenzoic acid, acetic acid, butyric acid, citric acid, formic acid, gluconic acid, glycolic acid, malonylglutaryl malonyl malonyl malonyl malonyl malonyl malonyl alanine.

[0029] By weight, the content of organic acid can account for 1% to 5% of the total weight of the etching solution. If the content of organic acid is less than 0.1%, the storage stability of the etching solution will be poor. If the content of organic acid is higher than 5%, the etching speed will be significantly slowed down, resulting in a slow etching process and a reduced etching effect.

[0030] Corrosion Inhibitor

[0031] In the present invention, azole compounds are selected as corrosion inhibitors. The corrosion inhibitor can adjust the etching speed of the alloy film, reduce the CD loss or side etch of the pattern, and thus improve the process margin.

[0032] Azoles used as corrosion inhibitors include aminotetrazolyl, benzotriazole, tolyltriazole, pyrazole, imidazole, 2-methylimidazole, 2-ethylimidazole, 2-propylimidazole, 4-methylimidazole, 4-methylimidazole, 4-methylimidazole, 4-methyltriazine, etc. These can be used alone or as a mixture of two or more.

[0033] The content of the corrosion inhibitor can be 0.01% to 5% of the total weight of the etching solution. If the content of the corrosion inhibitor is less than 0.01%, the etching rate of the etching solution increases, and a large CD loss may be generated. If the content of the corrosion inhibitor is higher than 5%, the etching rate will be significantly slowed down, and etching residues may be generated.

[0034] Organic base

[0035] In the present invention, an amine compound is selected as the organic base, and the organic base can prevent the copper ions dissolved after etching from further reacting with the oxidant, thereby preventing the etching reaction from getting out of control.

[0036] The amine compound in the present invention can be selected from monovalent, divalent or trivalent amine compounds, preferably trivalent amines with the strongest ability to bind copper, such as cyclohexylamine, 2-dimethylaminoethanol or 3-(diethylamino)propylamine. The above amine compounds can be selected from any one or a mixture of two or more thereof.

[0037] By weight, the content of organic base can account for 1% to 10% of the total weight of the etching solution. When the content of organic base is less than 1%, it will cause the organic base to not fully react with the copper ions dissolved after etching. When the content of organic base is greater than 10%, the reactivity of copper with the etching solution will be reduced, thereby slowing down the etching speed.

[0038] Deionized water

[0039] In the present invention, deionized water is selected as the etching solution solvent, and preferably deionized water with a resistivity value greater than 18 MΩ·cm is selected.

[0040] It should be noted that, in addition to the above-mentioned components, the etching solution of the present invention may also be added with conventional additives, such as etching regulators, metal ion blocking agents, preservatives, surfactants or pH regulators, including but not limited to these.

[0041] Example

[0042] This embodiment also provides a method for using a TFT metal film etching solution, comprising the following steps:

[0043] Step 1: forming a copper-based metal film on a substrate by thin film deposition technology;

[0044] The substrate in the present invention is a glass substrate, and the thin film deposition technology includes any one of a physical vapor deposition technology and a chemical vapor deposition technology. The copper-based metal film in the present invention includes a laminated film of copper / molybdenum or copper / molybdenum-niobium alloy, specifically, a molybdenum or molybdenum-niobium alloy thin film is first deposited on the surface of the substrate, and then a copper metal thin film is deposited on the surface of the molybdenum or molybdenum-niobium alloy thin film.

[0045] Step 2: coating the photoresist on the copper-based metal film by spin coating, spray coating or dipping, then exposing the photoresist by a specific light source, and placing the exposed substrate in a developer for development;

[0046] Clean the substrate on which the metal film has been deposited to remove impurities and contaminants on the surface of the substrate. Then, apply photoresist to the metal film by spin coating, spray coating or dipping. After applying the photoresist, bake it at 80-120°C for 5-15 minutes to cure the photoresist. After curing, place the substrate in a photolithography machine and expose the photoresist with ultraviolet light or electron beam. After exposure, place the substrate in a developer for development.

[0047] Step 3: Prepare etching solution and place the developed substrate into the etching solution for etching.

[0048] Specifically, weigh each component according to the ratio and composition described in Table 1 below. Mix the weighed organic acid component, corrosion inhibitor component and deionized water, and stir for 30 minutes until all the components are dissolved and mixed evenly. Add the organic base component to the above mixed solution, and keep stirring and adding during the addition to avoid violent reaction of the components. After the organic base component is added, keep stirring to room temperature, then add the metal film oxidant thereto, and continue stirring until the organic base and other components are evenly mixed to form an etching solution. The etching solution in the present invention includes the following components: metal oxidant, organic acid, organic base, corrosion inhibitor and deionized water.

[0049] After the etching solution is prepared according to the above-mentioned etching solution preparation method, the developed substrate is placed in the etching solution, and the etching solution temperature is controlled at 30-40°C to etch the substrate for 80-100 seconds until the ideal metal film etching morphology and pattern are obtained. The etching schematic diagram is shown in the attached figure. Figure 1 As shown, the etching results in the embodiment are as shown in the attached Figure 2 and 3 shown.

[0050] The specific proportion of the etching solution in the embodiment is shown in Table 1 below:

[0051] Table 1: Example group distribution ratio table

[0052]

[0053] The etching performance of the above-prepared etching solution was tested, and the test results are shown in Table 2 below:

[0054] Table 2: Example test results

[0055]

[0056]

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for using a TFT metal film etching solution, characterized in that: The following steps are involved: Step 1: forming a copper-based metal film on a substrate by thin film deposition technology; Step 2: coating the photoresist on the copper-based metal film by spin coating, spray coating or dipping, then exposing the photoresist by a specific light source, and placing the exposed substrate in a developer for development; Step 3: Prepare etching solution and place the developed substrate into the etching solution for etching.

2. The method for using a TFT metal film etching solution according to claim 1, characterized in that: The thin film deposition technology in step 1 includes any one of physical vapor deposition technology and chemical vapor deposition technology.

3. The method for using a TFT metal film etching solution according to claim 2, characterized in that: In the step 1, the copper-based metal film is a copper / molybdenum metal film or a copper / molybdenum-niobium alloy metal film.

4. The method for using a TFT metal film etching solution according to claim 1, characterized in that: The coating of the photoresist on the copper-based metal film in step 2 comprises the following steps: firstly removing impurities from the substrate, then coating the photoresist on the copper-based metal film, and finally baking at 80-120° C. for 5-15 minutes to solidify the photoresist.

5. The method for using a TFT metal film etching solution according to claim 1, characterized in that: The etching solution in step 3 includes the following components by mass fraction: 5-15% metal film oxidant, 1-5% organic acid, 1-10% organic base, 0.001-5% corrosion inhibitor, and the rest is deionized water.

6. The method for using a TFT metal film etching solution according to claim 5, characterized in that: The preparation of the etching solution in step three includes the following steps: S1. Weighing each component according to the weight ratio; S2. Stirring and mixing the organic acid, corrosion inhibitor and deionized water until all materials are completely dissolved; S3. Adding the organic base while stirring, adding the metal film oxidant after the solution is cooled to room temperature, and continuing to stir until the mixture is completely mixed.

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