Acid etching liquid for multilayer film of display panel as well as preparation method and application of acid etching liquid

Abstract

The invention relates to an acid etching solution for a multilayer film of a display panel, and a preparation method and application of the acid etching solution. The acid etching liquid for the multilayer film of the display panel comprises the following components in parts by weight: 42-54 parts of polybasic mixed acid; 4-6 parts of oxyacid; 1-3 parts of nitrate; 1-2.5 parts of a corrosion inhibitor; and 42-54 parts of ultrapure water. The corrosion inhibitor in the etching liquid is a combination of a thienone compound and vanadium oxychloride, and can be used as the corrosion inhibitor to slow down Mo layer metal etching, and Mura and Underer-cut phenomena are avoided. Compared with the traditional phosphoric acid etching solution, the etching solution provided by the invention has the advantages that the metal ion chelating capability is improved, and the etching life is longer.

Description

Technical Field

[0001] The invention belongs to the field of etching liquid, and in particular relates to an acid etching liquid for a display panel multilayer film, a preparation method and application thereof. Background Art

[0002] With the rapid advancement of technology, new display technologies such as OLED, QLED, and Micro LED have emerged, bringing higher image quality, lower energy consumption, and longer service life to the industry. At the same time, breakthroughs in flexible display technology have made display panels more diverse in form, providing more design possibilities for terminal products.

[0003] Taking the TFT-LCD manufacturing process as an example, when the thin film transistor liquid crystal display (TFT-LCD) is enlarged, the metal wires that transmit signals in the TFT-LCD will also be elongated, causing the resistance of the metal wires to increase, and the increase in resistance will cause signal delay. Therefore, some people have proposed using multiple metal layers to avoid signal delay, so it is necessary to provide an etching solution that can etch multiple metal layers to improve the efficiency of equipment and processes.

[0004] Molybdenum and aluminum films are mainly used in semiconductors, TFT and TP touch panels. Since the adhesion between aluminum or aluminum alloy and the glass substrate as the base film is poor and it is easily corroded by acids, alkalis and heat in the external environment, it is necessary to use molybdenum or molybdenum alloy film layers on the upper and lower parts of the aluminum or aluminum alloy as a laminated film, and use an etching solution to etch the laminated film together to produce the required pattern.

[0005] At present, etching solutions containing acid and oxidant are often used to etch Mo / Al multilayer metals. Since the etching speeds of the Mo layer and the Al layer in the etching solution are not matched, ordinary etching solutions often cause excessive critical dimension loss of the multilayer metals and a taper angle greater than or equal to 90 degrees. In addition, the substrate is also prone to color difference (Mura) and undercut problems.

[0006] Therefore, the present invention provides an acid etching solution for a display panel multilayer film and a preparation method thereof, which are used to etch Al-containing multilayer metal layers to solve the Mura and Under-cut problems generated by the multilayer metal etching solution currently used in the market after etching. Summary of the invention

[0007] The technical problem solved by the present invention is the Mura and Under-cut problems generated after etching of an Al-containing multilayer film substrate.

[0008] In view of the technical problems existing in the prior art, the present invention designs an acid etching solution for a display panel multilayer film and a preparation method thereof. The etching solution can be used in the field of etching Al-containing multilayer metal etching. The Mura and under-cut problems generated by Al-containing multilayer film substrates after etching are solved.

[0009] 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, as well as closed-ended "consisting of..." and similar meanings.

[0010] In order to solve the above-mentioned technical problems, the present invention adopts the following solutions:

[0011] An acid etching solution for a display panel multilayer film, characterized in that it comprises the following components calculated by weight:

[0012]

[0013] Furthermore, the polybasic mixed acid is one or more of tartaric acid, malic acid, citric acid and oxalic acid.

[0014] Furthermore, the polybasic mixed acid is citric acid and oxalic acid.

[0015] Furthermore, the mass ratio of citric acid to oxalic acid is 4.5-6:1.

[0016] Furthermore, the oxygen-containing acid is one or both of periodic acid and perchloric acid.

[0017] Furthermore, the oxygen-containing acid is preferably perchloric acid.

[0018] Furthermore, the nitrate is one or more of sodium nitrate, potassium nitrate, calcium nitrate and ammonium nitrate.

[0019] Furthermore, the nitrate is preferably calcium nitrate.

[0020] Furthermore, the corrosion inhibitor includes thiophenone compounds and vanadium oxychloride.

[0021] Furthermore, the mass ratio of the thiophenone compound to vanadium dichloride is 2-3:1.

[0022] Furthermore, the thiophenone compound is selected from any one of 2(5H)-thiophenone, tetrahydrothiophene-3-one, di(2-thiophene)one, and 6,7-dihydro-4-benzo(b)thiopheneone.

[0023] Furthermore, the thiophenone compound is preferably 2(5H)-thiophenone.

[0024] Furthermore, in the present invention, the ultrapure water used is deionized water with a resistance ≥ 18 MΩ.

[0025] The present invention also discloses a method for preparing an acid etching solution for a display panel multilayer film, which is characterized by comprising the following steps:

[0026] Step 1: Weigh each component in its respective amount;

[0027] Step 2: At 15-20°C, add all components except the corrosion inhibitor into the container and mix evenly. Finally, add the corrosion inhibitor and continue stirring for 20-30 minutes.

[0028] The present invention also discloses an etching method of an acid etching solution for a display panel multilayer film, which is characterized by comprising the following steps:

[0029] Step 1: In a sealed condition, the display panel multilayer film is heated to 35-40° C. with an acid etching solution, and after the temperature is stabilized, the substrate is placed in the etching solution and the substrate is vibrated at the same time;

[0030] Step 2: Rinse the etched substrate with ultrapure water at least twice to fully clean the residual etching solution, and finally blow dry with nitrogen to complete the etching.

[0031] The invention also discloses the use of an acid etching solution for a display panel multilayer film in etching a substrate containing an Al multilayer film.

[0032] Furthermore, the Al-containing multilayer film substrate includes a Mo / AlNd / Mo substrate, a Mo / Al / Mo substrate, a Ti / Al / Ti substrate, a Mo / Al substrate and a Mo / AlNd substrate.

[0033] In the present invention, in order to further optimize the etching effect, the acid etching solution for the display panel multilayer film can further preferably include: 44-54 parts of a polybasic mixed acid; 4.5-5 parts of an oxygen-containing acid; 1-2 parts of a nitrate; 1.6-2.5 parts of a corrosion inhibitor; and 44-54 parts of ultrapure water.

[0034] In the present invention, the mass ratio of citric acid to oxalic acid in the polybasic mixed acid is preferably 5:1.

[0035] In the present invention, the mass ratio of the thiophenone compound to the vanadium dichloride in the corrosion inhibitor is preferably 2:1; the corrosion inhibitor can inhibit the corrosion of the Mo layer metal.

[0036] It should be noted that in the preparation method, the temperature in step 1 is always maintained below 20° C., more preferably 15° C., in order to prevent excessive temperature and a large loss of oxalic acid.

[0037] The stirring speed of step 2 is 600-800r / min.

[0038] In the present invention, the etching method can also be referred to as a one-step etching method for substrates. In this method, the etching time is generally different for substrates of different thicknesses; generally, an etching time of 20-50% OE is recommended. The cleaning process in step 2 generally takes about 2 minutes.

[0039] In the present invention, the polybasic mixed acid has a special role:

[0040] First, citric acid provides hydrogen ions (acidic environment) to the etching solution, promoting the process of converting Mo, Al, and Nd oxides into ionic forms.

[0041] Secondly, citric acid can be used as a chelating agent in the system to chelate Mo, Al, and Nd ions in the system to prevent a large amount of metal ions from being adsorbed on the substrate.

[0042] Finally, oxalic acid provides hydrogen ions to the system, and the acidification promotes etching. At high concentrations, it has the effect of inhibiting Mo metal etching. At the same time, oxalic acid is a weak acid and has a certain buffering effect.

[0043] Oxalic acid and citric acid work synergistically with each other in terms of metal ion chelating performance and hydrogen ion acidification performance, so that the etching solution of the present invention has no Mura and Under-cut phenomenon after etching.

[0044] In the present invention, oxygen-containing acids have unique advantages:

[0045] Oxygen-containing acid is an oxidant in the system. Its main function is to oxidize metals such as Mo, Al, and Nd into corresponding oxides to accelerate etching. At the same time, it is also the main component that provides acidic conditions.

[0046] In the present invention, nitrate has unique advantages:

[0047] Nitrates provide nitrates to the etching solution, which assists oxidation and reduces the viscosity of the system.

[0048] The working principle of the corrosion inhibitor of the present invention is as follows:

[0049] The present invention adopts thiophenone compounds and vanadium oxychloride for synergistic corrosion inhibition.

[0050] First, thiophenone compounds are sulfur-containing heterocyclic organic compounds, which can easily form stable metal complexes with metal Mo, Al, and Nd ions in the etching solution system. Because the electrochemical reaction of Mo, Al, and Nd metals in the etching solution system will produce weak current to adsorb the metal. Therefore, the formed metal complex is adsorbed in the area where the electrochemical reaction is more intense. In the end, most of them are deposited and adsorbed in the areas where Mura and Under-cut appear on the substrate, forming a dense passivation film, thereby achieving corrosion inhibition.

[0051] Secondly, vanadium oxychloride can directly act on the metal surface of Mo, Al, Nd layer to form a thin film, which isolates the contact between metal Mo, Al, Nd and etching environment, thereby slowing down the etching reaction rate. On the other hand, it can also prevent metal Al, Nd, Mo ions from diffusing outward, thereby achieving the purpose of avoiding excessive etching rate of Mo, Al, Nd metal.

[0052] Thirdly, vanadium oxychloride can affect the electrode potential of Mo, Al, and Nd, change the surface electrochemical properties of Mo, Al, and Nd metals, make the metals more stable in the acidic environment of the etching solution, and reduce the rate of electrochemical corrosion.

[0053] The present invention provides an acid etching solution for a display panel multilayer film, a preparation method and use thereof, which have the following advantages: Effect :

[0054] 1. The etching solution of the present invention uses a combination of thiophenone compounds and vanadium oxychloride, which can act as a corrosion inhibitor to slow down the metal etching of the Mo layer and avoid the generation of Mura and Under-cut phenomena.

[0055] 2. The present invention uses citric acid to chelate metal ions. Citric acid has three carboxyl groups and one hydroxyl group. These functional groups can form multiple coordination bonds with metal ions to form stable chelates. Compared with traditional phosphoric acid-based etching solutions, the ability to chelate metal ions is improved, and the etching life is longer. The etching solution 1600L of the present invention can produce up to 10,000 pieces of wafers on the etching machine of the 4.5 generation line.

[0056] Therefore, the etching solution of the present invention has very good application prospects and large-scale industrial promotion potential in the field of display panel etching. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 : A SEM image of the substrate after etching using the etching solution of Comparative Example 3, magnified 50,000 times;

[0058] Figure 2 : This is a SEM image of the substrate after etching using the etching solution of Example 1, magnified 50,000 times. DETAILED DESCRIPTION

[0059] The present invention will be further described below in conjunction with specific embodiments and accompanying drawings:

[0060] The acid etching solutions for display panel multilayer films according to Examples 1-5 and Comparative Examples 1-4 of the present invention include components and mass ratios as shown in Tables 1 and 2.

[0061] The preparation method of the acid etching solution for the display panel multilayer film is as follows:

[0062] Step 1: Weigh each component in its respective amount;

[0063] Step 2: At a temperature of 15° C. and a stirring speed of 700 r / min, add all components except the corrosion inhibitor into a container and stir evenly. Finally, add the corrosion inhibitor and continue stirring for 20 minutes to obtain an acid etching solution.

[0064] Table 1 Example 1-Example 5

[0065]

[0066] Table 2 Comparative Examples 1-4

[0067]

[0068]

[0069] Regarding the etching method of the present invention:

[0070] Step 1: In a sealed condition, the display panel multilayer film is heated to 35° C. with an acid etching solution, and after the temperature is stabilized, the substrate is placed in the etching solution and the substrate is vibrated at the same time;

[0071] Step 2: Rinse the etched substrate with ultrapure water at least twice for 1 minute to fully clean the residual etching solution, and finally blow dry with nitrogen to complete the etching.

[0072] About performance testing and description:

[0073] Performance 1 Etching liquid life test method is:

[0074] The same volume (1600L) of etching solutions of the comparative example and the embodiment were respectively injected into the etching machine of the 4.5 generation line. The temperature was raised to 35°C. After the temperature stabilized, a substrate with a thickness of ( Mo / AlNd / Mo) was used for wafer production experiment, the etching time was 30OE, and other relevant process conditions were the same. The machine run rate was set to 12000 pieces. CD-loss was tested for every 2000 substrates, and when CD-loss was less than 1200nm, the run rate of the substrate was recorded. The test results are shown in Table 3.

[0075] As the number of wafers increases, the CD-loss of the substrate will show a downward trend. This is because as the number of wafers increases, the effective component content of the etching solution will gradually decrease, and the chelated metal ion content in the system will gradually increase, which will eventually lead to a decrease in the etching ability of the etching solution. When the CD-loss is lower than 1200nm, it cannot meet the etching requirements.

[0076] Performance 2Mura, Under-cut morphology, TAPER variance test methods are:

[0077] It should be noted that in the display panel industry, Mura refers to the phenomenon of uneven brightness of liquid crystal displays, that is, dark or inconsistent areas appear on the screen.

[0078] Using substrates of the same thickness specifications ( Mo / AlNd / Mo) was used for the experiment. A substrate was divided into 5 points and numbered respectively. The temperature of multiple groups of etching solutions of 100g comparative example and embodiment was raised to 35°C. After the temperature stabilized, the substrates were placed in different etching solutions for etching, and the etching time was 30OE. The substrates were taken out, washed and dried to obtain the etched substrates.

[0079] The etched substrate was split and sampled for SEM detection. The TAPER (°) of the Mo layer metal at 5 points on the substrate was calculated, and the variance of the TAPER (°) at the 5 points was calculated. The calculation results are shown in Table 3.

[0080] The SEM image of the surface effect after etching at the middle point of the substrate after etching, whether there is Mura or Under-cut, the test results refer to Figure 1-Figure 2 .

[0081] Table 3 Test results

[0082] life Mura and Under-cut TAPER Variance Example 1 10000 pieces No Mura and Under-cut area 0.08 Example 2 9400 pieces No Mura and Under-cut area 0.15 Example 3 9800 pieces No Mura and Under-cut area 0.09 Example 4 9400 pieces No Mura and Under-cut area 0.13 Example 5 9600 pieces No Mura and Under-cut area 0.11 Comparative Example 1 6000 pieces There are Mura and Under-cut areas 0.35 Comparative Example 2 5800 pieces There are Mura and Under-cut areas 0.40 Comparative Example 3 3000 pieces There are Mura and Under-cut areas 0.63 Comparative Example 4 4200 pieces No Mura and Under-cut area 0.88

[0083] Further analysis of the test results:

[0084] As can be seen from Table 3, the etching solutions of Comparative Examples 1-4 meet the requirements at CD-loss greater than 1200nm at 3000-6000 pieces, and the etching solutions of the present invention meet the requirements at CD-loss of 9400-10000 pieces, that is, the service life of the etching solutions of the present invention is longer. It can be seen that the service life of the etching solutions of the present invention on this machine is about 10,000 wafers. At the same time, it is proved that the rate at which the CD-loss of the etching solutions of Comparative Examples 1-4 decreases is faster than that of the etching solutions of the present invention, which shows that the effective component loss of the etching solutions of Comparative Examples 1-4 during use is faster than that of the etching solutions of the present invention, and further proves that the present invention can significantly improve the service life.

[0085] From the comparison of TAPER angle variance data, it can be seen that the uniformity of the etching solution of the embodiment of the present invention is much better than that of the etching solution of the comparative example, that is, the difference of etching parameters at different positions of the etching solution of the present invention is much smaller than that of the traditional etching solution.

[0086] Specifically, in Comparative Example 1, only vanadium oxychloride is used as the corrosion inhibitor. Due to the lack of the synergistic effect of thiophenone substances, the sustained release capacity of metal Mo is insufficient, resulting in Under-cut and Mura phenomena.

[0087] In Comparative Example 2, only 2(5H)-thiophenone is used as the corrosion inhibitor. Due to the lack of the synergistic effect of vanadium dichloride, the sustained release capacity of metal Mo is insufficient, resulting in Under-cut and Mura phenomena.

[0088] In Comparative Example 3, since no corrosion inhibitor is added, the metal Mo etching rate is aggravated, and severe Under-cut and Mura phenomena occur.

[0089] In Comparative Example 4, phosphoric acid accounts for a large proportion, resulting in too high viscosity of the solution system, poor etching uniformity, too large Taper angle variance, and poor etching uniformity.

[0090] Further comparison is made through the attached drawings in the specification:

[0091] Figure 1 This is a SEM image of the substrate after etching using the etching solution of Comparative Example 3, magnified 50,000 times; Figure 2 This is a SEM image of a substrate magnified 50,000 times after etching using the etching solution of Example 1 of the present invention.

[0092] pass Figure 1 and Figure 2 By comparison, it can be seen that under the same etching conditions, the substrate etched with the etching solution of Comparative Example 3 exhibits severe inward shrinkage of the Mo metal at the top and bottom, i.e., Mura and Under-cut areas. The substrate etched with the etching solution of Example 1 has a good morphology without Mura and Under-cut.

[0093] The etching solution of the present invention uses a combination of thiophenone compounds and vanadium dichloride, which can be used as a corrosion inhibitor to slow down the metal etching of the Mo layer and avoid the generation of Mura and Under-cut phenomena. The present invention uses citric acid to chelate metal ions. Citric acid has three carboxyl groups and one hydroxyl group. These functional groups can form multiple coordination bonds with metal ions to form stable chelates. Compared with the traditional phosphoric acid etching solution, the ability to chelate metal ions is improved and the etching life is extended. Compared with the etching solution using the traditional etching solution, that is, the etching solution of comparative example 3 (without additives, using phosphoric acid, nitric acid, acetic acid system and nitric acid accounts for a large proportion), the number of wafers of the etching machine of 1600L on the 4.5-generation line is about 3,000, and the number of wafers of the etching machine of the etching solution 1600L of the present invention on the 4.5-generation line can reach 10,000.

[0094] 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. An acid etching solution for a display panel multilayer film, characterized in that: Calculated by weight, it includes the following components:

2. The acid etching solution for display panel multilayer film according to claim 1, characterized in that: The polybasic mixed acid is one or more of tartaric acid, malic acid, citric acid and oxalic acid.

3. The acid etching solution for display panel multilayer film according to claim 2, characterized in that: The polybasic mixed acid is citric acid and oxalic acid; the mass ratio of citric acid to oxalic acid in the polybasic mixed acid is 4.5-6:

1.

4. The acid etching solution for display panel multilayer film according to claim 1, characterized in that: The oxygen-containing acid is one or both of periodic acid and perchloric acid.

5. The acid etching solution for display panel multilayer film according to claim 1, characterized in that: The nitrate is one or more of sodium nitrate, potassium nitrate, calcium nitrate and ammonium nitrate.

6. The acid etching solution for display panel multilayer film according to claim 1, characterized in that: The corrosion inhibitor comprises thiophenone compounds and vanadium oxychloride.

7. The acid etching solution for display panel multilayer film according to claim 6, characterized in that: The mass ratio of the thiophenone compound to vanadium dichloride in the corrosion inhibitor is (2-3):

1.

8. A method for preparing an acid etching solution for a display panel multilayer film according to any one of claims 1 to 7, characterized in that The following steps are involved: Step 1: Weigh the respective amounts of each component; Step 2: At 15-20°C, add all components except the corrosion inhibitor into a container and mix evenly. Finally, add the corrosion inhibitor and stir for 20-30 minutes.

9. An etching method for a display panel multilayer film using an acid etching solution according to any one of claims 1 to 7, characterized in that The following steps are involved: Step 1: In a sealed condition, the display panel multilayer film is heated to 35-40° C. with an acid etching solution, and after the temperature is stabilized, the substrate is placed in the etching solution and the substrate is vibrated at the same time; Step 2: Rinse the etched substrate with ultrapure water at least twice to fully clean the residual etching solution, and finally blow dry with nitrogen to complete the etching.

10. Use of the acid etching solution for display panel multilayer films according to any one of claims 1 to 7 in etching Al-containing multilayer film substrates.

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