Undercut-free copper etching liquid

Abstract

The invention belongs to the technical field of metal etching, and particularly discloses an undercut-free copper etching solution which comprises the following components in percentage by weight: 10-22% of hydrogen peroxide, 1-5% of a chelating agent, 0.02-0.5% of a corrosion inhibitor, 0.05-1% of a surfactant, 1-4% of a pH regulator, 0.1-0.5% of a solubilizer and the balance of deionized water. The chelating agent is prepared by carrying out polymerization reaction on carboxymethyl cellulose, a triethanolamine-epichlorohydrin polymer and a cysteine-epichlorohydrin polymer. According to the undercut-free copper etching liquid provided by the invention, the chelating agent, the corrosion inhibitor, the surfactant, the solubilizer, the pH regulator and the like are added on the basis of hydrogen peroxide, so that the etching taper angle is regulated, controlled and stabilized, and no undercut is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal etching, and particularly relates to a copper etching solution without undercut. Background Art

[0002] In the current display technology field, the trend of planar displays towards larger sizes and higher resolutions is becoming increasingly significant, which stems from users' continuous pursuit of a better visual experience. However, as the panel size increases, the wire impedance rises accordingly, resulting in a decrease in the signal transmission speed, which poses more stringent requirements for the transmission performance and stability of electrical signals. To adapt to the development of the panel industry, using metal copper and its alloys with excellent electrical conductivity and outstanding electromigration resistance characteristics to replace aluminum and its alloys can significantly reduce the wire impedance and current loss, thereby effectively improving the signal transmission speed.

[0003] It should be noted that the application of copper materials poses new requirements for the supporting etching process. Currently, the commonly used copper etching solution adopts a hydrogen peroxide system. For example, the invention patent CN117926257A discloses a copper etching solution without undercut and without phosphorus, including a solvent, hydrogen peroxide, sulfuric acid, a hydrogen peroxide stabilizer, a shore protection agent, an etching rate stabilizer, and a penetrant; the concentration of hydrogen peroxide is 20 - 160 g / L; the concentration of sulfuric acid is 40 - 140 g / L; the concentration of the hydrogen peroxide stabilizer is 0.1 - 10 g / L; the concentration of the shore protection agent is 0.1 - 10 g / L; the concentration of the etching rate stabilizer is 0.1 - 20 g / L; the concentration of the penetrant is 0.1 - 30 g / L; during the etching process, the concentration of copper ions will continuously increase, accelerating the decomposition of hydrogen peroxide and causing instability in the etching process; at the same time, due to isotropic etching, there will be adverse phenomena such as side etching, etching cone angle, and undercut, affecting the product yield. Therefore, it is necessary to develop a copper etching solution that can effectively control the etching cone angle and improve the undercut phenomenon in etching. Summary of the Invention

[0004] The purpose of the present invention is to provide a copper etching solution without undercut to solve the problems existing in the prior art that during the etching process of the copper etching solution system, the concentration of copper ions continuously increases, resulting in unstable etching process, and due to isotropic etching, there are adverse phenomena such as side etching, etching cone angle, and undercut.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] The present invention provides a copper etching solution without undercut, which comprises the following components by weight percentage: 10 - 22% hydrogen peroxide, 1 - 5% chelating agent, 0.02 - 0.5% corrosion inhibitor, 0.05 - 1% surfactant, 1 - 4% pH regulator, 0.1 - 0.5% solubilizer, and the balance is deionized water;

[0007] The chelating agent is obtained by the polymerization reaction of carboxymethyl cellulose, triethanolamine-epichlorohydrin polymer and cysteine-epichlorohydrin polymer.

[0008] Furthermore, the preparation method of the chelating agent comprises the following steps:

[0009] Add carboxymethyl cellulose into the sodium hydroxide solution, stir at 55 - 65 °C for 1.5 - 2.5 h, then slowly dropwise add the triethanolamine-epichlorohydrin polymer and cysteine-epichlorohydrin polymer. After the dropping is completed, react at 70 - 80 °C for 2 - 6 h, filter, wash, and dry to obtain the chelating agent.

[0010] Furthermore, the dosage ratio of the carboxymethyl cellulose, triethanolamine-epichlorohydrin polymer, cysteine-epichlorohydrin polymer to the sodium hydroxide solution is (5 - 10) g : (3 - 5) g : (1 - 2) g : 50 mL;

[0011] The concentration of the sodium hydroxide solution is 2 - 10 wt%.

[0012] Even further, the concentration of the sodium hydroxide solution is 5 wt%.

[0013] Furthermore, the preparation method of the triethanolamine-epichlorohydrin polymer comprises the following steps:

[0014] Add triethanolamine into the lithium hydroxide solution, mix evenly, heat up to 80 - 90 °C, slowly dropwise add epichlorohydrin. After the dropping is completed, continue to keep the temperature for reaction for 6 - 8 h, cool to room temperature, and filter to obtain the triethanolamine-epichlorohydrin polymer.

[0015] Even further, the dosage ratio of the triethanolamine, epichlorohydrin and lithium hydroxide solution is (7.4 - 7.5) g : (16.5 - 18.5) g : 20 mL;

[0016] The concentration of the lithium hydroxide solution is 2 - 10 wt%.

[0017] Even further, the concentration of the lithium hydroxide solution is 5 wt%.

[0018] Furthermore, the preparation method of the cysteine-epichlorohydrin polymer comprises the following steps:

[0019] Dissolve cysteine in the PBS buffer solution, then add EDTA, mix evenly, heat up to 35 - 40 °C, slowly dropwise add epichlorohydrin. After the dropping is completed, stir and react at 45 - 75 °C for 2 - 6 h, cool to room temperature, and filter to obtain the cysteine-epichlorohydrin polymer.

[0020] Further, the dosage ratio of the cysteine, epichlorohydrin, EDTA, and PBS buffer solution is (6.0 - 6.1) g : (9.2 - 9.8) g : 0.01 g : 20 mL.

[0021] Further, the corrosion inhibitor is any one or more of picolinic acid, benzimidazole, piperazine, quinoline, thiourea, benzotriazole, benzothiazole, mixed in any proportion.

[0022] Further, the surfactant is any one or more of sodium alkylnaphthalene sulfonate, sodium isopropylnaphthalene sulfonate, sodium butylnaphthalene sulfonate, sodium dodecylbenzenesulfonate, mixed in any proportion.

[0023] Further, the solubilizer is any one or more of ethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monoethyl ether, mixed in any proportion;

[0024] The pH regulator is any one or more of ethanolamine, triethanolamine, isopropanolamine, diisopropanolamine, methanesulfonic acid, mixed in any proportion.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. In the present invention, the chelating agent is obtained by the polymerization reaction of carboxymethyl cellulose, triethanolamine - epichlorohydrin polymer, and cysteine - epichlorohydrin polymer. Specifically, during the reaction of carboxymethyl cellulose with triethanolamine - epichlorohydrin polymer and cysteine - epichlorohydrin polymer, the epoxy group will open the ring and react with the carboxyl group on carboxymethyl cellulose and connect to form a cellulose cross - linked polymer, that is, the chelating agent is obtained. The molecular chain of the chelating agent of the present invention contains various active functional groups, such as carboxyl, amino, and mercapto groups, which can all chelate with free copper ions to form chelates soluble in the etching solution, effectively slowing down the decomposition of hydrogen peroxide, and then stabilizing the etching rate of the etching solution. At the same time, the chelating agent has different affinities for different crystal planes of copper crystals, and is more likely to adsorb on the (100) crystal plane of metallic copper. In copper crystals, the copper atoms at the edges or corners have unsaturated coordination, and there will also be more empty orbitals to form coordination bonds with the functional groups of the chelating agent. Therefore, during the etching process, the etching rates of different crystal planes will be different, so as to achieve different etching rates in the horizontal and vertical directions, effectively improving the adverse phenomena of side etching, etching cone angle, and undercut.

[0027] 2. In the present invention, the corrosion inhibitor is selected from heterocyclic hydrocarbons containing oxygen or nitrogen, which helps to reduce the non-uniformity of the etching rate and make the etching process more uniform and controllable. The combined use of a surfactant and a solubilizer can improve the dissolution performance of the etching solution, enhance the wettability of the etching solution on the photoresist and copper surface, and better disperse and dissolve copper ions and their chelates in the copper etching solution near the photoresist-copper interface, controlling the side etching rate at the interface. Without affecting other etching parameter indicators, the cone angles (the angles formed by lateral etching and longitudinal etching) etched by the etching solutions with different copper ion concentrations are stable and consistent, and the etching life of the copper etching solution is extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings described herein are used to provide a further understanding of the present invention and form a part of this application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0029] Figure 1 is the SEM image of the copper substrate after being etched by the copper etching solution provided in Embodiment 1 of the present invention;

[0030] Figure 2 is the SEM image of the copper substrate after being etched by the copper etching solution provided in Embodiment 2 of the present invention;

[0031] Figure 3 ]>is the SEM image of the copper substrate after being etched by the copper etching solution provided in Embodiment 3 of the present invention;

[0032] Figure 4 is the SEM image of the copper substrate after being etched by the copper etching solution provided in Comparative Example 1 of the present invention;

[0033] Figure 5 is the SEM image of the copper substrate after being etched by the copper etching solution provided in Comparative Example 2 of the present invention;

[0034] Figure 6 is the SEM image of the copper substrate after being etched by the copper etching solution provided in Comparative Example 3 of the present invention;

[0035] Figure 7 is the SEM image of the copper substrate after being etched by the copper etching solution provided in Comparative Example 4 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0037] Preparation Example 1

[0038] This preparation example provides a method for preparing a chelating agent, which includes the following steps:

[0039] S1. Add 7.4 g of triethanolamine to 20 mL of lithium hydroxide solution (concentration: 5 wt%), mix evenly, heat up to 80 °C, slowly dropwise add 16.5 g of epichlorohydrin. After the addition is completed, continue to keep the temperature for reaction for 6 h, cool to room temperature, filter, collect the filtrate to obtain triethanolamine-epichlorohydrin polymer;

[0040] S2. Dissolve 6.0 g of cysteine in 20 mL of PBS buffer solution, then add 0.01 g of EDTA, mix evenly, heat up to 35 °C, slowly dropwise add 9.2 g of epichlorohydrin. After the addition is completed, stir and react at 45 °C for 2 h, cool to room temperature, filter, collect the filtrate to obtain cysteine-epichlorohydrin polymer;

[0041] S3. Dissolve 5 g of carboxymethyl cellulose in 50 mL of sodium hydroxide solution (concentration: 5 wt%), stir at 55 °C for 1.5 h, then slowly dropwise add 3 g of triethanolamine-epichlorohydrin polymer and 1 g of cysteine-epichlorohydrin polymer. After the addition is completed, react at 70 °C for 2 h, filter, wash, and dry to obtain the chelating agent.

[0042] Preparation Example 2

[0043] This preparation example provides a method for preparing a chelating agent, which includes the following steps:

[0044] S1. Add 7.45 g of triethanolamine to 20 mL of lithium hydroxide solution (concentration: 5 wt%), mix evenly, heat up to 85 °C, slowly dropwise add 17.5 g of epichlorohydrin. After the addition is completed, continue to keep the temperature for reaction for 7 h, cool to room temperature, filter to obtain triethanolamine-epichlorohydrin polymer;

[0045] S2. Dissolve 6.05 g of cysteine in 20 mL of PBS buffer solution, then add 0.01 g of EDTA, mix evenly, heat up to 38 °C, slowly dropwise add 9.6 g of epichlorohydrin. After the addition is completed, stir and react at 60 °C for 4 h, cool to room temperature, filter to obtain cysteine-epichlorohydrin polymer;

[0046] S3. Dissolve 8 g of carboxymethyl cellulose in 50 mL of sodium hydroxide solution (concentration: 5 wt%), stir at 60 °C for 2 h, then slowly dropwise add 4 g of triethanolamine-epichlorohydrin polymer and 1.5 g of cysteine-epichlorohydrin polymer. After the addition is completed, react at 75 °C for 4 h, filter, wash, and dry to obtain the chelating agent.

[0047] Preparation Example 3

[0048] This preparation example provides a method for preparing a chelating agent, which includes the following steps:

[0049] S1. Add 7.5 g of triethanolamine to 20 mL of lithium hydroxide solution (concentration: 5 wt%), mix evenly, heat up to 90 °C, slowly dropwise add 18.5 g of epichlorohydrin. After the dropping is completed, continue to carry out the heat preservation reaction for 8 h, cool to room temperature, filter to obtain triethanolamine-epichlorohydrin polymer;

[0050] S2. Dissolve 6.1 g of cysteine in 20 mL of PBS buffer solution, then add 0.01 g of EDTA, mix evenly, heat up to 40 °C, slowly dropwise add 9.8 g of epichlorohydrin. After the dropping is completed, carry out the stirring reaction at 75 °C for 6 h, cool to room temperature, filter to obtain cysteine-epichlorohydrin polymer;

[0051] S3. Dissolve 10 g of carboxymethyl cellulose in 50 mL of sodium hydroxide solution (concentration: 5 wt%), stir at 65 °C for 2.5 h, then slowly dropwise add 5 g of triethanolamine-epichlorohydrin polymer and 2 g of cysteine-epichlorohydrin polymer. After the dropping is completed, carry out the reaction at 80 °C for 6 h, filter, wash, and dry to obtain the chelating agent.

[0052] Comparative Preparation Example 1

[0053] This comparative preparation example provides a method for preparing a chelating agent, which includes the following steps:

[0054] S1. Add 7.4 g of triethanolamine to 20 mL of lithium hydroxide solution (concentration: 5 wt%), mix evenly, heat up to 80 °C, slowly dropwise add 16.5 g of epichlorohydrin. After the dropping is completed, continue to carry out the heat preservation reaction for 6 h, cool to room temperature, filter, and collect the filtrate to obtain triethanolamine-epichlorohydrin polymer;

[0055] S2. Dissolve 5 g of carboxymethyl cellulose in 50 mL of sodium hydroxide solution (concentration: 5 wt%), stir at 55 °C for 1.5 h, then slowly dropwise add 4 g of triethanolamine-epichlorohydrin polymer. After the dropping is completed, carry out the reaction at 70 °C for 2 h, filter, wash, and dry to obtain the chelating agent.

[0056] Comparative Preparation Example 2

[0057] This comparative preparation example provides a method for preparing a chelating agent, which includes the following steps:

[0058] S1. Dissolve 6.0 g of cysteine in 20 mL of PBS buffer solution, then add 0.01 g of EDTA, mix well, heat to 35 °C, slowly add 9.2 g of epichlorohydrin dropwise. After the addition is complete, stir and react at 45 °C for 2 h, cool to room temperature, filter, and collect the filtrate to obtain cysteine-epichlorohydrin polymer;

[0059] S2. Dissolve 5 g of carboxymethyl cellulose in 50 mL of sodium hydroxide solution (concentration 5 wt%), stir at 55 °C for 1.5 h, then slowly add 4 g of cysteine-epichlorohydrin polymer dropwise. After the addition is complete, react at 70 °C for 2 h, filter, wash, and dry to obtain the chelating agent.

[0060] Example 1

[0061] This example provides a copper etchant without undercut, including the following components by weight percentage: 18% hydrogen peroxide, 3% chelating agent, 0.3% corrosion inhibitor, 0.05% surfactant, 3% pH regulator, 0.3% solubilizer, and the balance is deionized water;

[0062] In this example, the chelating agent is prepared from Preparation Example 1; the corrosion inhibitor is picolinic acid; the surfactant is alkylnaphthalenesulfonate; the pH regulator is ethanolamine; the solubilizer is propylene glycol monomethyl ether.[[ID=;13]]

[0063] Example 2

[0064] This example provides a copper etchant without undercut, including the following components by weight percentage: 10% hydrogen peroxide, 1% chelating agent, 0.02% corrosion inhibitor, 0.5% surfactant, 1% pH regulator, 0.1% solubilizer, and the balance is deionized water;

[0065] In this example, the chelating agent is prepared from Preparation Example 2; the corrosion inhibitor is benzimidazole; the surfactant is sodium dodecylbenzenesulfonate; the pH regulator is isopropanolamine; the solubilizer is diethylene glycol monobutyl ether.

[0066] Example 3

[0067] This example provides a copper etchant without undercut, including the following components by weight percentage: 22% hydrogen peroxide, 5% chelating agent, 0.5% corrosion inhibitor, 1% surfactant, 4% pH regulator, 0.5% solubilizer, and the balance is deionized water;

[0068] In this example, the chelating agent is prepared from Preparation Example 3; the corrosion inhibitor is benzothiazole; the surfactant is isopropylnaphthalenesulfonate; the pH regulator is triethanolamine; the solubilizer is propylene glycol monomethyl ether.

[0069] Comparative Example 1

[0070] This comparative example provides a copper etchant without undercut, which comprises the following components by weight percentage: 18% hydrogen peroxide, 3% chelating agent, 0.3% corrosion inhibitor, 0.05% surfactant, 3% pH regulator, 0.3% solubilizer, and the balance is deionized water;

[0071] In this comparative example, the chelating agent is prepared from Comparative Preparation Example 1; the corrosion inhibitor is picolinic acid; the surfactant is alkylnaphthalenesulfonate; the pH regulator is ethanolamine; the solubilizer is propylene glycol monoethyl ether.

[0072] Comparative Example 2

[0073] This comparative example provides a copper etchant without undercut, which comprises the following components by weight percentage: 18% hydrogen peroxide, 3% chelating agent, 0.3% corrosion inhibitor, 0.05% surfactant, 3% pH regulator, 0.3% solubilizer, and the balance is deionized water;

[0074] In this comparative example, the chelating agent is prepared from Comparative Preparation Example 2; the corrosion inhibitor is picolinic acid; the surfactant is alkylnaphthalenesulfonate; the pH regulator is ethanolamine; the solubilizer is propylene glycol monoethyl ether.

[0075] Comparative Example 3

[0076] This comparative example provides a copper etchant without undercut, which comprises the following components by weight percentage: 18% hydrogen peroxide, 3% chelating agent, 0.3% corrosion inhibitor, 0.35% surfactant, 3% pH regulator, and the balance is deionized water;

[0077] In this comparative example, the chelating agent is prepared from Preparation Example 1; the corrosion inhibitor is picolinic acid; the surfactant is alkylnaphthalenesulfonate; the pH regulator is ethanolamine.

[0078] Comparative Example 4

[0079] This comparative example provides a copper etchant without undercut, which comprises the following components by weight percentage: 18% hydrogen peroxide, 3% chelating agent, 0.3% corrosion inhibitor, 3% pH regulator, 0.35% solubilizer, and the balance is deionized water;

[0080] In this comparative example, the chelating agent is prepared from Preparation Example 1; the corrosion inhibitor is picolinic acid; the pH regulator is ethanolamine; the solubilizer is propylene glycol monoethyl ether.

[0081] Performance Test

[0082] An etching experiment was carried out on the copper etchants provided in the above Examples 1-3 and Comparative Examples 1-4 to study their etching performance. The specific method is as follows:

[0083] Prepare 100 mL of the above copper etching solution, add 0.03 g of copper powder thereto and dissolve it, place it in a water bath at 33 °C, etch the copper substrate, measure the undercut amount and the taper angle by SEM, and characterize the stability of the etching taper angle and the presence or absence of undercut. The specific test results are shown in Table 1.

[0084] Prepare 3 groups of 100 mL of the above copper etching solution, add 0.03 g, 0.5 g, and 1 g of copper powder thereto respectively and dissolve them to obtain copper etching solutions with copper ion concentrations of 300 ppm, 5000 ppm, and 10000 ppm respectively. Place the 300 ppm, 5000 ppm, and 10000 ppm copper etching solutions in a water bath at 33 °C, monitor the temperature change of the etching solution, and record the time taken for the etching solution to reach the highest temperature; generally, the temperature of the etching solution does not change significantly for a long time. However, when the internal balance of the etching solution cannot be maintained, the etching solution will heat up rapidly within a very short time. Therefore, record the time taken for the etching solution to reach this highest temperature to characterize the safety of the etching solution, and the longer the time used, the better the safety. The specific test results are shown in Table 2.

[0085] Table 1

[0086] Group Cone Angle With or Without Undercut Example 1 48.81° No Example 2 48.11° No Example 3 47.22° No Comparative Example 1 55.80° Yes Comparative Example 2 56.17° Yes Comparative Example 3 46.48° Yes Comparative Example 4 46.10° Yes

[0087] Figures 1 - 7 SEM images of the copper substrate after etching with the copper etching solutions provided in Examples 1-3 and Comparative Examples 1-4 respectively. From the data in Table 1 and Figures 1 - 7 it can be seen that compared with the copper etching solutions provided in Comparative Examples 1-4, the copper etching solutions provided in Examples 1-3 have excellent etching stability, significantly improving the adverse phenomena of undercut, etching taper angle, and undercut.

[0088] Specifically, the chelating agent in Comparative Example 1 is prepared by reacting triethanolamine-epichlorohydrin polymer with carboxymethyl cellulose, and the chelating agent in Comparative Example 2 is prepared by reacting cysteine-epichlorohydrin polymer with carboxymethyl cellulose. Thus, by comparing Example 1 with Comparative Examples 1 and 2, it can be seen that if only the chelating agent prepared by reacting triethanolamine-epichlorohydrin polymer or cysteine-epichlorohydrin polymer with carboxymethyl cellulose is used, the etching performance of the prepared copper etching solution is significantly reduced.

[0089] Compared with Example 1, in Comparative Example 3, an equal amount of surfactant is used to replace the solubilizer, and compared with Example 1, in Comparative Example 4, an equal amount of solubilizer is used to replace the surfactant. Thus, by comparing Example 1 with Comparative Examples 3 and 4, it can be seen that if only surfactant or solubilizer is used, although there is an improvement in the etching angle, undercut cannot be reduced.

[0090] Table 2

[0091]

[0092] As can be seen from Table 2, at the same temperature and the same copper ion concentration, compared with the copper etching solutions provided in Comparative Examples 1-4, the etching solutions obtained in Examples 1-3 exhibited long life.

[0093] Specifically, the chelating agent in Comparative Example 1 was prepared by reacting triethanolamine-epichlorohydrin polymer with carboxymethyl cellulose, and the chelating agent in Comparative Example 2 was prepared by reacting cysteine-epichlorohydrin polymer with carboxymethyl cellulose. Thus, by comparing Example 1 with Comparative Examples 1 and 2, it shows that the chelating agent of the present invention is obtained by the polymerization reaction of carboxymethyl cellulose, triethanolamine-epichlorohydrin polymer and cysteine-epichlorohydrin polymer, which helps to improve the life of the copper etching solution.

[0094] Compared with Example 1, in Comparative Example 3, an equal amount of surfactant was used to replace the solubilizer, and compared with Example 1, in Comparative Example 4, an equal amount of solubilizer was used to replace the surfactant. Thus, by comparing Example 1 with Comparative Examples 3 and 4, it shows that adding a surfactant and a solubilizer in the etching solution of the present invention has a synergistic effect and jointly prolongs the etching life of the copper etching solution.

[0095] In the description of this specification, the descriptions referring to the terms "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0096] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art of this industry should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A copper etching solution without undercut, characterized in that, By weight percentage, it includes the following components: 10-22% hydrogen peroxide, 1-5% chelating agent, 0.02-0.5% corrosion inhibitor, 0.05-1% surfactant, 1-4% pH regulator, 0.1-0.5% solubilizer, and the balance is deionized water; The chelating agent is obtained by the polymerization reaction of carboxymethyl cellulose, triethanolamine-epichlorohydrin polymer and cysteine-epichlorohydrin polymer.

2. The copper etching solution without undercut according to claim 1, wherein The preparation method of the chelating agent includes the following steps: Add carboxymethyl cellulose into sodium hydroxide solution, stir at 55-65 °C for 1.5-2.5 h, then slowly dropwise add triethanolamine-epichlorohydrin polymer and cysteine-epichlorohydrin polymer. After the dropping is completed, react at 70-80 °C for 2-6 h, filter, wash, and dry to obtain the chelating agent.

3. A copper etching solution without undercut according to claim 2, wherein, The dosage ratio of the carboxymethyl cellulose, triethanolamine-epichlorohydrin polymer, cysteine-epichlorohydrin polymer to the sodium hydroxide solution is (5-10) g:(3-5) g:(1-2) g:50 mL; The concentration of the sodium hydroxide solution is 2-10 wt%.

4. The copper etching solution without undercut according to claim 2, wherein The preparation method of the triethanolamine-epichlorohydrin polymer includes the following steps: Add triethanolamine into lithium hydroxide solution, mix evenly, heat up to 80-90 °C, slowly dropwise add epichlorohydrin. After the dropping is completed, continue to keep warm and react for 6-8 h, cool to room temperature, and filter to obtain triethanolamine-epichlorohydrin polymer.

5. A copper etching solution without undercutting according to claim 4, characterized in that, The dosage ratio of the triethanolamine, epichlorohydrin and lithium hydroxide solution is (7.4-7.5) g:(16.5-18.5) g:20 mL; The concentration of the lithium hydroxide solution is 2-10 wt%.

6. The copper etching solution without undercut according to claim 2, wherein The preparation method of the cysteine-epichlorohydrin polymer includes the following steps: Dissolve cysteine in PBS buffer solution, then add EDTA, mix evenly, heat up to 35-40 °C, slowly dropwise add epichlorohydrin. After the dropping is completed, stir and react at 45-75 °C for 2-6 h, cool to room temperature, and filter to obtain cysteine-epichlorohydrin polymer.

7. An undercut-free copper etchant according to claim 6, wherein, The dosage ratio of the cysteine, epichlorohydrin, EDTA and PBS buffer solution is (6.0-6.1) g:(9.2-9.8) g:0.01 g:20 mL.

8. A copper etching solution without undercutting according to claim 1, characterized in that, The corrosion inhibitor is any one or more of picolinic acid, benzimidazole, piperazine, quinoline, thiourea, benzotriazole, benzothiazole mixed in any proportion.

9. A copper etching solution without undercutting according to claim 1, characterized in that, The surfactant is any one or more of sodium alkyl naphthalene sulfonate, sodium isopropyl naphthalene sulfonate, sodium butyl naphthalene sulfonate, sodium dodecyl benzene sulfonate mixed in any proportion.

10. A copper etching solution without undercut according to claim 1, characterized in that, The solubilizer is any one or more of ethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monoethyl ether mixed in any proportion; The pH regulator is any one or more of ethanolamine, triethanolamine, isopropanolamine, diisopropanolamine, methanesulfonic acid mixed in any proportion.

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