Multi-thickness film layer compatible cu etching liquid and method of use thereof

Abstract

The application provides a Cu etching liquid compatible with multiple thickness film layers and a use method thereof, and relates to the technical field of metal film layer etching. The Cu etching liquid is composed of hydrogen peroxide, a weak organic acid, an alcohol amine corrosion inhibitor, polyethylene glycol, phosphoric acid, sodium bisulfate, polyaspartic acid sodium, and tri-potassium glycyrrhizinate, and the ratio of the sum of the mass percentages of the phosphoric acid and the sodium sulfate to the sum of the mass percentages of the polyaspartic acid sodium and the tri-potassium glycyrrhizinate is less than or equal to 1.5. The application overcomes the defects of the prior art, and the obtained Cu etching liquid can effectively etch Cu / MTD substrates with different thicknesses, and ensures the stability of etching under different copper concentrations.

Description

Technical Field

[0001] This invention relates to the field of metal film etching technology, and specifically to a Cu etching solution compatible with multiple film thicknesses and its application method. Background Technology

[0002] With the development of the display industry, the manufacturing size of LCD panels is constantly increasing, and the precision requirements for TFT manufacturing are becoming increasingly stringent. Therefore, copper metal materials with lower resistance are being used more widely. During copper metal wiring, direct contact with other films such as Si is inevitable. Due to the inherent properties of copper, it is prone to oxidation and diffusion into other films, leading to device performance failure. Therefore, high-performance metal or alloy films are often used as transition layers between copper and other films. The most commonly used transition layer is MTD (Medium-to-Density Surface Mount), i.e., using Cu / MTD as the substrate material. The thickness of the substrate material used generally varies depending on the requirements and application scenarios. Therefore, the etching agent used must be able to achieve good results on materials of different thicknesses.

[0003] Currently, the etching solutions used for Cu / MTD substrates compatible with different film thicknesses are mainly acidic copper chloride systems and alkaline copper ammonium complex ion systems. Precise control is achieved by adding chelating agents, auxiliary etchants, and inhibitors. However, in actual use, the etching rate is affected by the concentration of Cu ions, requiring real-time monitoring and adjustment. This poses a significant obstacle to the etching of continuous substrates in enterprises, severely impacting production efficiency and increasing processing costs. Therefore, adjusting the composition of the etchant to achieve stable etching effects for Cu / MTD substrates compatible with different film thicknesses and different copper concentrations in the etching solution is a major research direction at present. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a Cu etching solution compatible with multiple film thicknesses and its application method, which can effectively etch Cu / MTD substrates of different thicknesses and ensure the stability of etching under different copper concentrations.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A Cu etching solution compatible with multiple film thicknesses, the etching solution being composed of the following raw materials in the following mass percentages: 15-30% hydrogen peroxide, 1.0%-5.0% weak organic acid, 0.5%-3% alkanolamine corrosion inhibitor, 0.5%-3% polyethylene glycol, 0.02%-0.06% phosphoric acid, 0.12%-0.18% sodium bisulfate, 0.06%-0.12% sodium polyaspartate, 0.02%-0.06% tripotassium glycyrrhizate, and water to make up to 100%; and the ratio of the sum of the mass percentages of phosphoric acid and sodium bisulfate to the sum of the mass percentages of sodium polyaspartate and tripotassium glycyrrhizate is ≤1.5.

[0006] Preferably, the weak organic acid is any one or a combination of citric acid, salicylic acid, tartaric acid, lactic acid, and acetic acid.

[0007] Preferably, the alcohol amine corrosion inhibitor is isopropanolamine.

[0008] Preferably, the preparation method of the Cu etching solution mainly includes the following steps: first, a weak organic acid and sodium bisulfate are mixed according to their respective contents and then water is added and stirred initially; then hydrogen peroxide, phosphoric acid, sodium polyaspartate and tripotassium glycyrrhizate are added in sequence and stirred continuously; finally, polyethylene glycol and alkanolamine corrosion inhibitors are added and stirred evenly to obtain the Cu etching solution.

[0009] Preferably, the initial stirring time is 1-2 minutes and the stirring speed is 120-400 r / min; the continued stirring time is 5-15 minutes and the stirring speed is 120-400 r / min; the time for uniform stirring is 25-35 minutes and the stirring speed is 400-800 r / min.

[0010] Preferably, the Cu etching solution is applied to the etching of copper / molybdenum nickel-titanium alloy substrates with different film thicknesses.

[0011] Preferably, the Cu etching solution is used by spraying, with a spray pressure of 0.1-0.2 MPa and an etching temperature of 25-35°C. During etching, the etching time is controlled to be extended by 40%-60% for over-etching.

[0012] This invention provides a Cu etching solution compatible with multiple film thicknesses and its application method, which has the following advantages compared with the prior art: This invention, by adding phosphoric acid, sodium bisulfate, sodium polyaspartate, and tripotassium glycyrrhizate to the etching solution and limiting the ratio of the sum of the mass percentages of phosphoric acid and sodium bisulfate to the sum of the mass percentages of sodium polyaspartate and tripotassium glycyrrhizate to ≤1.5, can simultaneously meet the requirements for multiple film thicknesses while maintaining stable etching performance even as the copper ion concentration in the solution continuously increases. This enables continuous and long-term production in actual production processes, reduces production costs, and improves production convenience. Attached Figure Description

[0013] Figure 1 This is a schematic diagram illustrating the etching process of a Cu / MTD 2500 / 300Å substrate by etching solution S1 in a system with a copper concentration of 300 ppm, as described in an embodiment of the present invention. Figure 2 This is a schematic diagram illustrating the etching process of a Cu / MTD 2500 / 300Å substrate by etching solution S1 in a system with a copper concentration of 3000 ppm, as described in an embodiment of the present invention. Figure 3 This is a schematic diagram illustrating the etching process of a Cu / MTD 2500 / 300Å substrate by etching solution S1 in a system with a copper concentration of 6000ppm in an embodiment of the present invention. Figure 4 This is a schematic diagram illustrating the etching process of a Cu / MTD 3800 / 300Å substrate by etching solution S1 in a system with a copper concentration of 300 ppm, as described in an embodiment of the present invention. Figure 5 This is a schematic diagram illustrating the etching process of a Cu / MTD 3800 / 300Å substrate by etching solution S1 in a system with a copper concentration of 3000 ppm, as described in an embodiment of the present invention. Figure 6 This is a schematic diagram illustrating the etching process of a Cu / MTD 3800 / 300Å substrate by etching solution S1 in a system with a copper concentration of 6000ppm in an embodiment of the present invention. Figure 7 This is a schematic diagram illustrating the etching process of a Cu / MTD 6500 / 300Å substrate by etching solution S1 in a system with a copper concentration of 300 ppm, as described in an embodiment of the present invention. Figure 8 This is a schematic diagram illustrating the etching process of etching solution S1 on a Cu / MTD 6500 / 300Å substrate in a system with a copper concentration of 3000ppm, as described in an embodiment of the present invention. Figure 9 This is a schematic diagram illustrating the etching process of a Cu / MTD 6500 / 300Å substrate by etching solution S1 in a system with a copper concentration of 6000ppm in an embodiment of the present invention. Figure 10 This is a schematic diagram illustrating the etching process of a Cu / MTD 2500 / 300Å substrate by etching solution S2 in a system with a copper concentration of 300 ppm, as described in an embodiment of the present invention. Figure 11 This is a schematic diagram illustrating the etching process of a Cu / MTD 2500 / 300Å substrate by etching solution S2 in a system with a copper concentration of 3000ppm in an embodiment of the present invention. Figure 12This is a schematic diagram illustrating the etching process of a Cu / MTD 2500 / 300Å substrate by etching solution S2 in a system with a copper concentration of 6000ppm in an embodiment of the present invention. Figure 13 This is a schematic diagram illustrating the etching process of a Cu / MTD 3800 / 300Å substrate by etching solution S2 in a system with a copper concentration of 300 ppm, as described in an embodiment of the present invention. Figure 14 This is a schematic diagram illustrating the etching process of a Cu / MTD 3800 / 300Å substrate by etching solution S2 in a system with a copper concentration of 3000 ppm, as described in an embodiment of the present invention. Figure 15 This is a schematic diagram illustrating the etching process of a Cu / MTD 3800 / 300Å substrate by etching solution S2 in a system with a copper concentration of 6000ppm in an embodiment of the present invention. Figure 16 This is a schematic diagram illustrating the etching process of a Cu / MTD 6500 / 300Å substrate by etching solution S2 in a system with a copper concentration of 300 ppm, as described in an embodiment of the present invention. Figure 17 This is a schematic diagram illustrating the etching process of a Cu / MTD 6500 / 300Å substrate by etching solution S2 in a system with a copper concentration of 3000 ppm, as described in an embodiment of the present invention. Figure 18 This is a schematic diagram illustrating the etching process of a Cu / MTD 6500 / 300Å substrate by etching solution S2 in a system with a copper concentration of 6000ppm in an embodiment of the present invention. Figure 19 This is a schematic diagram illustrating the etching process of a Cu / MTD 2500 / 300Å substrate by etching solution S3 in a system with a copper concentration of 300 ppm, as described in an embodiment of the present invention. Figure 20 This is a schematic diagram illustrating the etching process of etching solution S3 on a Cu / MTD 2500 / 300Å substrate in a system with a copper concentration of 3000ppm, as described in an embodiment of the present invention. Figure 21 This is a schematic diagram illustrating the etching process of a Cu / MTD 2500 / 300Å substrate by etching solution S3 in a system with a copper concentration of 6000ppm in an embodiment of the present invention. Figure 22 This is a schematic diagram illustrating the etching process of a Cu / MTD 3800 / 300Å substrate by etching solution S3 in a system with a copper concentration of 300 ppm, as described in an embodiment of the present invention. Figure 23 This is a schematic diagram illustrating the etching process of a Cu / MTD 3800 / 300Å substrate by etching solution S3 in a system with a copper concentration of 3000ppm in an embodiment of the present invention. Figure 24 This is a schematic diagram illustrating the etching process of a Cu / MTD 3800 / 300Å substrate by etching solution S3 in a system with a copper concentration of 6000ppm in an embodiment of the present invention. Figure 25 This is a schematic diagram illustrating the etching process of a Cu / MTD 6500 / 300Å substrate by etching solution S3 in a system with a copper concentration of 300 ppm, as described in an embodiment of the present invention. Figure 26 This is a schematic diagram illustrating the etching process of a Cu / MTD 6500 / 300Å substrate by etching solution S3 in a system with a copper concentration of 3000ppm in an embodiment of the present invention. Figure 27 This is a schematic diagram illustrating the etching process of a Cu / MTD 6500 / 300Å substrate by etching solution S3 in a system with a copper concentration of 6000ppm, as described in an embodiment of the present invention. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] Example 1: Etching solution formula: Prepare different etchants according to the formulations in Table 1 below (the weak organic acid used in the table is citric acid, and the alcohol amine corrosion inhibitor is isopropanolamine), expressed as a mass percentage, with the remainder being water: Table 1

[0016] Preparation of etching solution: According to the formula in Table 1 above, First, citric acid and sodium bisulfate are mixed and then water is added. The mixture is stirred at 200 rpm for 2 minutes. Then, hydrogen peroxide, phosphoric acid, sodium polyaspartate and tripotassium glycyrrhizate are added in sequence and the mixture is stirred at 200 rpm for 10 minutes. Finally, polyethylene glycol and isopropanolamine are added and the stirring speed is adjusted to 600 rpm for 30 minutes to obtain etching solutions S1, S2 and S3.

[0017] Etching effect inspection: 1. Testing method: Etching substrates: Cu / MTD (copper / molybdenum nickel-titanium alloy) 2500 / 300Å; Cu / MTD 3800 / 300Å; Cu / MTD 6500 / 300Å.

[0018] Etching conditions: Etching machine, temperature 29℃, spray pressure 0.1MPa, substrate size 5cm×5cm, etching time O / E 45% (O / E Over Etch, etching time is 45% over-etching). Etching process: Pour etching solution into the equipment. After the temperature stabilizes, place the prepared substrate into the mini etching machine, turn on the equipment, and start spraying. Observe the EPD (End Point Detection, the time when the substrate begins to be exposed) of the substrate. Etch according to O / E 45% (EPD*1.45sec, after the EPD detects the etching endpoint, continue etching for an additional 1.45 seconds, and the over-etching amount accounts for 45% of the target total etching amount). Take out the substrate, clean it, and store it for later use. During the etching process, it is necessary to simulate the copper ion concentration of the solution in the production line to reach 300, 3000, and 6000 PPM before etching.

[0019] SEM imaging: The etched substrate was made to the size required for SEM imaging, placed inside the SEM, and relevant data were captured at a magnification of 50K. Results are as follows: Figures 1-27 As shown in the figure, 1 represents the S / E value, 2 represents the Tail value, and 3 represents the T / A value.

[0020] The specific experimental results are shown in Table 2 below: Table 2

[0021] Where T / E / T (Total Etch Time) is the total etching time; S / E (Side Etch) is the distance from the end of the photoresist to the metal end; T / A (Taper Angel) is the angle formed by the upper and lower metal layers; and Tail is the distance from the lower Cu to the end of the lower MTD layer.

[0022] Depend on Figures 1-27 As shown in Table 2 above, the etching solution S1 can effectively etch Cu / MTD substrates of different thicknesses, and its overall etching effect is more stable than that of S2 and S3 in environments with different copper concentrations in the solution.

[0023] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A Cu etching solution compatible with multiple film thicknesses, characterized in that, The etching solution is composed of the following raw materials in the indicated mass percentages: 15-30% hydrogen peroxide, 1.0%-5.0% weak organic acid, 0.5%-3% alkanolamine corrosion inhibitor, 0.5%-3% polyethylene glycol, 0.02%-0.06% phosphoric acid, 0.12%-0.18% sodium bisulfate, 0.06%-0.12% sodium polyaspartate, 0.02%-0.06% tripotassium glycyrrhizate, and water to make up to 100%. Furthermore, the ratio of the sum of the mass percentages of phosphoric acid and sodium bisulfate to the sum of the mass percentages of sodium polyaspartate and tripotassium glycyrrhizate is ≤1.5; The Cu etching solution is used for etching copper / molybdenum nickel-titanium alloy substrates with different film thicknesses.

2. The Cu etching solution compatible with multiple film thicknesses according to claim 1, characterized in that: The weak organic acid is any one or a combination of citric acid, salicylic acid, tartaric acid, lactic acid, and acetic acid.

3. The Cu etching solution compatible with multiple film thicknesses according to claim 1, characterized in that: The alkanolamine corrosion inhibitor is isopropanolamine.

4. The Cu etching solution compatible with multiple film thicknesses according to claim 1, characterized in that, The preparation method of the Cu etching solution mainly includes the following steps: First, weak organic acid and sodium bisulfate are mixed in the appropriate amounts and then water is added and stirred initially. Then, hydrogen peroxide, phosphoric acid, sodium polyaspartate and tripotassium glycyrrhizate are added in sequence and stirred continuously. Finally, polyethylene glycol and alkanolamine corrosion inhibitors are added and stirred evenly to obtain Cu etching solution.

5. The Cu etching solution compatible with multiple film thicknesses according to claim 4, characterized in that, The initial stirring time is 1-2 minutes, and the stirring speed is 120-400 r / min; the continued stirring time is 5-15 minutes, and the stirring speed is 120-400 r / min; the time for uniform stirring is 25-35 minutes, and the stirring speed is 400-800 r / min.

6. The Cu etching solution compatible with multiple film thicknesses according to claim 1, characterized in that, The Cu etching solution is used by spraying at a pressure of 0.1-0.2 MPa and an etching temperature of 25-35°C. During etching, the etching time is extended by 40%-60% for over-etching.

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