ITO (indium tin oxide) and IGZO (indium gallium zinc oxide) etching solution for panel display and preparation method thereof

Abstract

The invention provides an ITO (Indium Tin Oxide) and IGZO (Indium Gallium Zinc Oxide) etching solution for panel display. The ITO and IGZO etching solution comprises the following components in parts by weight: 40-60 parts of mixed acid, 4-6 parts of phosphate, 0.3-0.6 part of a buffering agent, 1-3 parts of a chelating agent, 2-5 parts of a surfactant, 1-3 parts of an inhibitor and 35-45 parts of water, the mass ratio of the inorganic acid to the organic acid in the mixed acid is 1: (3-5); the etching solution prepared by the method has the advantages of high selectivity, good controllability and good surface quality, and can be applied to ITO and IGZO for panel display; the etching rate of the etching liquid is 18-20 / s, the single-side CDlos is smaller than or equal to 0.8 mu m, and the accommodating capacity (In, Sn) is smaller than or equal to 3000 ppm.

Description

Technical Field

[0001] The invention belongs to the technical field of panel display etching, and specifically relates to an ITO and IGZO etching solution for a flat panel display and a preparation method thereof. Background Art

[0002] With the development of display technology, liquid crystal displays are gradually developing in the direction of large size and high resolution, which means that the charging time of pixels is getting shorter and shorter. The thin film transistors in the display screen play a vital role in pixel charging. The characteristics of TFT are largely determined by the properties of the active layer. Traditional TFT devices usually use amorphous silicon as the active layer. AS-TFT devices have been developed for a long time and have stable device characteristics, but the mobility of AS is low. Under the development trend of high resolution and high refresh rate, it has gradually lost its original advantages. Another semiconductor material, indium gallium zinc oxide, is highly praised by people because of its high mobility and suitability for large-area production. It has become a research hotspot in the field of thin film transistor technology. IGZO has a greater mobility than AS, which can make TFT have a faster charging rate, and can make TFT smaller, further improve the pixel aperture ratio, and reduce backlight consumption. On the other hand, the leakage current of IGZO-TFT devices themselves is small, which is also a benefit for the power consumption of the liquid crystal panel itself.

[0003] The stability of current IGZO-TFT devices needs to be improved. The IGZO active layer is very sensitive to the process and environment, and is easily affected by light, temperature, etc. At the same time, it is also greatly affected by the process. For example, the Q-time of the IGZO process is particularly affected by the IGZO etching solution in the IGZO dominant process. For example, the etching uniformity of the etching solution itself, whether the etching solution will introduce some conductive impurities, the etching rate is too fast, and the lateral corrosion is severe, etc., which greatly affect the stability of the IGZO-TFT device, such as causing the IGZO Vth (turn-on voltage) to drift or the leakage current to be abnormal.

[0004] Although a variety of etching solutions based on acid solutions and acid salt solutions have been disclosed in the prior art, these etchants are very likely to cause side etching on the etching surface. This is because both weak acid and strong acid solutions are liquid solution etching materials, which inevitably have the characteristics of too fast H+ release, low surface tension, and easy volatility when heated, causing changes in etching concentration, which makes the etching develop in the depth direction, resulting in low controllability, severe side etching, product etching damage, affecting product characteristics, and reducing product yield in the etching process. Summary of the invention

[0005] The purpose of the present invention is to provide an ITO and IGZO etching solution for flat panel displays and a preparation method thereof, which uses a mixed acid as the main etching component and is supplemented with ingredients such as phosphate, a buffer, a surfactant and an inhibitor, thereby ensuring that the prepared etching solution has the advantages of high selectivity, good controllability and good surface quality, and can be applied to ITO and IGZO for flat panel displays.

[0006] In order to achieve the above object, the present invention provides the following technical solutions: An ITO and IGZO etching solution for flat panel displays comprises the following components in parts by weight: 40-60 parts of mixed acid, 4-6 parts of phosphate, 0.3-0.6 parts of buffer, 1-3 parts of chelating agent, 2-5 parts of surfactant, 1-3 parts of inhibitor and 35-45 parts of water; the mass ratio of inorganic acid to organic acid in the mixed acid is 1:3-5.

[0007] Furthermore, the inorganic acid is one of phosphoric acid, nitric acid, sulfuric acid, and hydrochloric acid, or a mixture thereof; the organic acid is one of malonic acid, citric acid, acetic acid, and oxalic acid, or a mixture thereof.

[0008] Furthermore, the inorganic acid is a mixture of phosphoric acid, nitric acid and sulfuric acid in a mass ratio of 1:1.5-1.8:2-2.3; the organic acid is a mixture of malonic acid, acetic acid, oxalic acid and citric acid in a mass ratio of 1:1.3-1.5:1.7-2:2-2.5.

[0009] Furthermore, the phosphate is one of dihydrogen phosphate and hydrogen phosphate or a mixture; the buffer is one of thiamine and nitramine or a mixture; the surfactant is a mixture of anionic surfactants, cationic surfactants and amphoteric surfactants; the chelating agent is EDTA; and the inhibitor is a mixture of hexadecanol, octadecyl alcohol, n-propanol and n-butanol.

[0010] Furthermore, the phosphate is a mixture of potassium dihydrogen phosphate and potassium hydrogen phosphate in a mass ratio of 1:1-3; the buffer is a mixture of thiamine and nitramine in a mass ratio of 1:0.5-1; the surfactant is a mixture of anionic surfactant, cationic surfactant and nonionic surfactant in a mass ratio of 1:1.5-2:1.8-2.2; the inhibitor is a mixture of hexadecanol, octadecyl alcohol, n-propanol and n-butanol in a mass ratio of 1:0.5-0.8:1-2:0.8-1.5.

[0011] Furthermore, the anionic surfactant is sodium dodecylbenzene sulfonate or sodium stearate; the cationic surfactant is hexadecyltrimethylammonium chloride; and the nonionic surfactant is lauryl alcohol polyoxyethylene ether or Tween-80.

[0012] The method for preparing the above-mentioned flat panel display ITO and IGZO etching solution comprises the following steps; S1: prepare the mixed acid, phosphate, buffer, surfactant and inhibitor respectively; S2: Stir and mix 40-60 parts of the mixed acid, 4-6 parts of phosphate and 35-45 parts of water described in step S1 for 20-30 minutes; raise the temperature to 35-45° C., add 2-5 parts of surfactant and 1-3 parts of inhibitor thereto, and continue stirring and mixing for 15-25 minutes; S3: Continue to raise the temperature to 70-80°C, add 0.3-0.6 parts of buffer and 1-3 parts of chelating agent, continue to stir and mix for 25-35 minutes, and after cooling, obtain ITO and IGZO etching solution for flat panel display.

[0013] Any of the above-prepared etching solutions is applied to ITO and IGZO for flat panel displays.

[0014] Compared with the prior art, the advantages and beneficial effects of the present invention are: The present invention uses inorganic acid and organic acid as mixed acid, and by selecting a reasonable ratio between the components, it has good etching selectivity, which can not only meet the etching requirements, but also avoid over-etching or damage to the underlying material; at the same time, auxiliary components such as phosphate, buffer, chelating agent, surfactant, inhibitor, etc. are added during the preparation process, which is conducive to controlling the stability of the etching rate, reducing the concentration fluctuation of the etching solution, effectively improving the etching accuracy, increasing the surface wettability of the film layer, enhancing the etching uniformity, and improving the surface quality. The etching rate of the etching solution prepared by the present invention is: 18-20Å / second, single-sided CDloss≤0.8um, and (In, Sn)≤3000ppm. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1

[0016] The present embodiment provides a method for preparing an ITO and IGZO etching solution for a flat panel display, comprising the following steps; S1: Phosphoric acid, nitric acid and sulfuric acid are mixed in a mass ratio of 1:1.5:2 to form an inorganic acid; malonic acid, acetic acid, oxalic acid and citric acid are mixed in a mass ratio of 1:1.3:1.7:2 to form an organic acid; Potassium dihydrogen phosphate and potassium hydrogen phosphate are mixed in a mass ratio of 1:1 to form phosphate; thiamine and ammonium nitrate are mixed in a mass ratio of 1:0.5 to form a buffer; anionic surfactants, cationic surfactants and nonionic surfactants are mixed in a mass ratio of 1:1.5:1.8 to form a surfactant; wherein the anionic surfactant is sodium dodecylbenzene sulfonate; the cationic surfactant is hexadecyltrimethylammonium chloride; the nonionic surfactant is lauryl alcohol polyoxyethylene ether; hexadecanol, octadecyl alcohol, n-propanol and n-butanol are mixed in a mass ratio of 1:0.5:1:0.8 to form an inhibitor; S2: 40 g of the mixed acid, 4 g of phosphate and 35 g of water in step S1 were stirred and mixed at a rate of 500 r / min for 20 min; the temperature was raised to 35° C., 2 g of surfactant and 1 g of inhibitor were added thereto, and the stirring and mixing was continued at a rate of 350 r / min for 15 min; S3: Continue to raise the temperature to 70° C., add 0.3 g of buffer and 1 g of chelating agent EDTA, continue to stir and mix at a rate of 400 r / min for 25 min, and after cooling, obtain ITO and IGZO etching solution for flat panel display. Example 2

[0017] The present embodiment provides a method for preparing an ITO and IGZO etching solution for a flat panel display, comprising the following steps; S1: Phosphoric acid, nitric acid and sulfuric acid are mixed in a mass ratio of 1:1.8:2.3 to form an inorganic acid; malonic acid, acetic acid, oxalic acid and citric acid are mixed in a mass ratio of 1:1.5:2:2.5 to form an organic acid; Potassium dihydrogen phosphate and potassium hydrogen phosphate are mixed in a mass ratio of 1:3 to form phosphate; thiamine and ammonium nitrate are mixed in a mass ratio of 1:1 to form a buffer; anionic surfactant, cationic surfactant and nonionic surfactant are mixed in a mass ratio of 1:2:2.2 to form a surfactant; wherein the anionic surfactant is sodium stearate; the cationic surfactant is hexadecyltrimethylammonium chloride; the nonionic surfactant is Tween-80; hexadecanol, octadecyl alcohol, n-propanol and n-butanol are mixed in a mass ratio of 1:0.8:2:1.5 to form an inhibitor; S2: 60 g of the mixed acid, 6 g of phosphate and 45 g of water in step S1 were stirred and mixed at a rate of 500 r / min for 30 min; the temperature was raised to 45° C., 5 g of surfactant and 3 g of inhibitor were added thereto, and the stirring and mixing was continued at a rate of 350 r / min for 25 min; S3: Continue to raise the temperature to 80° C., add 0.6 g of buffer and 3 g of chelating agent EDTA, continue to stir and mix at a rate of 400 r / min for 35 min, and after cooling, obtain ITO and IGZO etching solution for flat panel display. Example 3

[0018] The present embodiment provides a method for preparing an ITO and IGZO etching solution for a flat panel display, comprising the following steps; S1: Phosphoric acid, nitric acid and sulfuric acid are mixed in a mass ratio of 1:1.7:2.2 to form an inorganic acid; malonic acid, acetic acid, oxalic acid and citric acid are mixed in a mass ratio of 1:1.4:1.9:2.3 to form an organic acid; Potassium dihydrogen phosphate and potassium hydrogen phosphate are mixed in a mass ratio of 1:2 to form phosphate; thiamine and ammonium nitrate are mixed in a mass ratio of 1:0.7 to form a buffer; anionic surfactants, cationic surfactants and nonionic surfactants are mixed in a mass ratio of 1:1.8:2 to form a surfactant; wherein the anionic surfactant is sodium dodecylbenzene sulfonate; the cationic surfactant is hexadecyltrimethylammonium chloride; the nonionic surfactant is lauryl alcohol polyoxyethylene ether; hexadecanol, octadecyl alcohol, n-propanol and n-butanol are mixed in a mass ratio of 1:0.7:1.5:1.2 to form an inhibitor; S2: 55 g of the mixed acid, 5 g of phosphate and 40 g of water in step S1 were stirred and mixed at a rate of 500 r / min for 25 min; the temperature was raised to 42° C., 4 g of surfactant and 2 g of inhibitor were added thereto, and the stirring and mixing was continued at a rate of 350 r / min for 20 min; S3: Continue to raise the temperature to 75° C., add 0.4 g of buffer and 2 g of chelating agent, continue to stir and mix at a rate of 400 r / min for 30 min, and after cooling, obtain ITO and IGZO etching solution for flat panel display.

[0019] Comparative Example 1 The difference from Example 1 is that in step S2, an inorganic acid is used instead of a mixed acid, and the other steps remain unchanged.

[0020] Comparative Example 2 The difference from Example 1 is that in step S2, an organic acid is used instead of a mixed acid, and the other steps remain unchanged.

[0021] Comparative Example 3 The difference from Example 1 is that phosphate, surfactant and inhibitor are not added in step S2, and other steps remain unchanged.

[0022] Comparative Example 4 The difference from Example 1 is that no buffer and chelating agent are added in step S3, and the other steps remain unchanged.

[0023] The etching solutions obtained in the examples and comparative examples were applied to IGZO for flat panel displays. Performance test: Determination of the etching rate of IGZO. The test sample used is a 100mm x 100mm glass substrate on which a 1000Å thick IGZO film is evaporated. Etching is performed at 30°C using the etching solutions of the above-mentioned embodiments and comparative examples. The etching conditions are to spray the etching solution at 0.1MPa and maintain the exhaust pressure in the etching area at 20Pa. After etching, the etching rate is measured using an optical thin film property measuring device n&k Analyzer 1280 (n&k Technology Inc.). Using a scanning electron microscope (SEM), the edge of the etched pattern can be observed with high resolution, and its actual size can be measured and compared with the designed size. By analyzing the size difference on both sides of the pattern, the single-sided CD Loss is tested. The (In, Sn) value is tested using spectral analysis. The results are shown in the following table.

[0024] Table 1

[0025] It can be seen from the above performance test results that the etching solutions prepared in Examples 1-3 have good etching rate, single-sided CDloss and holding value, and have good surface quality and selectivity. In particular, Example 3 has excellent comprehensive performance. However, because Comparative Examples 1-4 do not adopt the necessary technical solutions, their corresponding performance tests are significantly worse than those of the embodiments. The above experimental results further prove the importance of the technical solutions defined in the present invention for its technical effects.

[0026] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An ITO and IGZO etching solution for flat panel display, characterized in that: The invention comprises the following components in parts by weight: 40-60 parts of mixed acid, 4-6 parts of phosphate, 0.3-0.6 parts of buffer, 1-3 parts of chelating agent, 2-5 parts of surfactant, 1-3 parts of inhibitor and 35-45 parts of water; the mass ratio of inorganic acid to organic acid in the mixed acid is 1:3-5.

2. The ITO and IGZO etching solution for flat panel display according to claim 1, characterized in that: The inorganic acid is one of phosphoric acid, nitric acid, sulfuric acid, and hydrochloric acid, or a mixture thereof; the organic acid is one of malonic acid, citric acid, acetic acid, and oxalic acid, or a mixture thereof.

3. The ITO and IGZO etching solution for flat panel display according to claim 1, characterized in that: The phosphate is one of dihydrogen phosphate and hydrogen phosphate or a mixture thereof; the buffer is one of thiamine and nitramine or a mixture thereof; the surfactant is a mixture of anionic surfactants, cationic surfactants and amphoteric surfactants; the chelating agent is EDTA; and the inhibitor is a mixture of hexadecanol, octadecyl alcohol, n-propanol and n-butanol.

4. The ITO and IGZO etching solution for flat panel display according to claim 3, characterized in that: The phosphate is a mixture of potassium dihydrogen phosphate and potassium hydrogen phosphate in a mass ratio of 1:1-3; the buffer is a mixture of thiamine and nitramine in a mass ratio of 1:0.5-1; the surfactant is a mixture of anionic surfactant, cationic surfactant and nonionic surfactant in a mass ratio of 1:1.5-2:1.8-2.2; the inhibitor is a mixture of hexadecanol, octadecyl alcohol, n-propanol and n-butanol in a mass ratio of 1:0.5-0.8:1-2:0.8-1.

5.

5. The ITO and IGZO etching solution for flat panel display according to claim 4, characterized in that: The anionic surfactant is sodium dodecylbenzene sulfonate or sodium stearate; the cationic surfactant is hexadecyltrimethylammonium chloride; and the nonionic surfactant is lauryl alcohol polyoxyethylene ether or Tween-80.

6. A method for preparing ITO and IGZO etching solutions for flat panel displays, characterized in that: The steps include: S1: prepare the mixed acid, phosphate, buffer, surfactant and inhibitor respectively; S2: Stir and mix 40-60 parts of the mixed acid, 4-6 parts of phosphate and 35-45 parts of water described in step S1 for 20-30 minutes; raise the temperature to 35-45° C., add 2-5 parts of surfactant and 1-3 parts of inhibitor thereto, and continue stirring and mixing for 15-25 minutes; S3: Continue to raise the temperature to 70-80°C, add 0.3-0.6 parts of buffer and 1-3 parts of chelating agent, continue to stir and mix for 25-35 minutes, and after cooling, obtain ITO and IGZO etching solution for flat panel display.

7. The etching solution prepared according to any one of claims 1 to 6 is applied to ITO and IGZO for flat panel displays.

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