A copper seed layer etching solution for a copper-nickel-gold structure and its application

Abstract

The application discloses a copper seed layer etching solution for copper-nickel-gold structure, which comprises 5-50 wt% of oxidizing agent, 1-40 wt% of carboxyl compound, 0.01-15 wt% of chelating agent, 0-0.01 wt% of additive and deionized water. The application also provides application of the copper seed layer etching solution for copper-nickel-gold structure in wafer etching, especially wafer etching for copper-nickel-gold structure. The etching solution has little damage to metals such as nickel and gold, has high protection ability to aluminum, has low lateral corrosion amount at copper-nickel joint, has low undercut amount of copper column, has stable etching rate within service life, and has high etching uniformity.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor packaging, and in particular to a copper seed layer etching solution of a copper-nickel-gold structure and applications thereof. Background Art

[0002] During the integrated circuit manufacturing process, it's often necessary to define extremely fine patterns on wafers. These patterns are primarily created through etching, transferring the photoresist pattern created by microlithography onto the underlying material, creating the complex architecture of the integrated circuits. After chip fabrication, specialized packaging houses create solder joints, or bumps, on the wafers to provide the interconnect media for subsequent chip interconnections. This process is known as advanced packaging. Similarly, packaging houses also use patterning to rearrange the interconnects or create bumps. After wafer fabrication, the first step is to use a magnetron sputtering machine to deposit a layer of titanium and a layer of copper, known in the industry as a seed layer, across the entire surface of the wafer. The titanium layer is sputtered to ensure a better bond with the wafer, while the copper layer is sputtered to create connections for the subsequent copper electroplating. Before copper electroplating, photoresist is patterned to ensure that the copper plating lands within the openings. As can be seen, the purpose of sputtering titanium and copper across the entire surface is to provide a dielectric for conducting current during electroplating, ensuring that the entire surface opening is plated with metal. A single wafer typically contains dozens to tens of chips. Due to the presence of the copper and titanium layers, all interconnects on the chips are electrically connected, effectively short-circuiting. Therefore, the initial sputtered titanium and copper must be removed by etching to ensure that the chip's interconnect bumps retain the specified electrical properties. Therefore, etching technology plays a crucial role in semiconductor manufacturing and advanced packaging. Broadly speaking, etching encompasses techniques for uniformly removing material across the entire surface and selectively removing patterns. These techniques can be broadly categorized into wet etching and dry etching. Currently, wet etching is widely used in chip bump manufacturing due to its low cost, high reliability, high throughput, and superior etching selectivity.

[0003] Although wet etching is widely used in advanced packaging processes due to its special advantages, the etching solutions in the industry still have the following disadvantages:

[0004] 1. Due to isotropic etching, side etching is very likely to occur;

[0005] 2. Undercut is prone to occur;

[0006] 3. Electrode damage problem;

[0007] 4. Incomplete and uneven etching caused by bubbles formed during the etching chemical reaction.

[0008] At the same time, in addition to the above-mentioned issues, wet etching also needs to consider the etching reaction rate and the corrosion of the etching solution on the mask (ie, the metal bump structure mentioned in the article).

[0009] In the current chip manufacturing process, the bumps are generally gold bumps (Au Bump), thick copper bumps (Copper Pillar Bump), tin-silver bumps (Solder Bump). Currently, gold bumps are mostly used in display drivers (DDI, TDDI). Its structure before etching is as follows Figure 1 As shown, the thickness of the Au seed layer is generally The height of the electroplated Au bumps varies from 8 to 20μm. However, gold, as a precious metal, is very expensive compared to metals such as copper and nickel. If all bumps are made of gold, the production cost will be very high. Therefore, the chip packaging industry urgently needs to solve the problem of high production costs in the bump research and development process. At present, a wave of technological reforms is being set off in the chip packaging field, which is expected to significantly reduce packaging costs and chip prices. The use of lower-priced copper to replace gold is shown in the simulation diagram of the bump formation. Figure 2 As shown in the figure, the bump part is replaced by copper for most of the gold, and the seed layer is also replaced by copper for gold, wherein the thickness of the Cu seed layer is generally Although the copper seed layer is thicker than the gold seed layer, Figure 2 The bumps and copper seed layers formed by copper, nickel and gold can completely replace Figure 1 Gold bumps and gold seed layers. Therefore, the corresponding seed layer etching must also be changed from the original gold etching to copper etching, while also avoiding damage to the gold, nickel and copper on the bumps. The existing technology mainly uses a persulfate formula to corrode the seed layer, which will cause significant damage to the nickel layer and thus affect the electrical properties of the wafer. The existing hydrogen peroxide system formula in the industry, although it has acceptable protection performance for nickel, has very serious undercutting of copper. Due to the Galvani effect, a potential difference is generated between the two metals, and a current is generated through the medium, which then produces an electrochemical reaction. The anode with a high potential is oxidized, and the side corrosion of the copper-nickel bonding layer is aggravated (such as Figure 4 As shown in the figure, the contact area of ​​the electrodes is reduced, which greatly reduces the reliability of the chip solder joints. Summary of the Invention

[0010] In order to solve the technical problems existing in the prior art, the present invention provides a copper seed layer etching solution of a copper-nickel-gold structure, wherein the etching solution comprises 5 to 50 wt% of an oxidant, 1 to 40 wt% of a carboxyl compound, 0.01 to 15 wt% of a chelating agent, 0 to 0.01 wt% of an additive, and deionized water.

[0011] As a preferred technical solution, the oxidant is selected from at least one of hydrogen peroxide, potassium persulfate, and sodium persulfate.

[0012] As a preferred technical solution, the carboxyl compound is selected from a mixture of one or more of citric acid, acetic acid, tartaric acid, malic acid, formic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, glycolic acid, acrylic acid, methacrylic acid, lactic acid, gluconic acid, maleic acid, benzoic acid, and salicylic acid.

[0013] As a preferred technical solution, the number of types of the carboxyl compounds is one to five.

[0014] As a preferred technical solution, when there are two carboxyl compounds, one is selected from at least one of acetic acid, oxalic acid, and formic acid, and the other is selected from at least one of malic acid, lactic acid, acrylic acid, tartaric acid, citric acid, benzoic acid, maleic acid, and salicylic acid.

[0015] As a preferred technical solution, the chelating agent is selected from a mixture of one or more of sodium gluconate, sodium citrate, and amino acids.

[0016] As a preferred technical solution, the amino acid is selected from a mixture of one or more of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, alanine, glycine, aspartic acid, glutamic acid, sarcosine, L-cysteine, lysine, cysteine, and methionine.

[0017] As a preferred technical solution, the types of amino acids are one to five.

[0018] As a preferred technical solution, the additive is an ionic compound and / or an inorganic acid.

[0019] The present invention also provides a use of the copper seed layer etching solution of the copper-nickel-gold structure described above in wafer etching.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The etching solution of the present invention changes the conductivity of the etching solution by replacing the acid environment in the hydrogen peroxide system, and adding additives to change the degree of ionization of the solute in the system, thereby further adjusting the conductivity of the etching solution.

[0022] 2. Existing technologies often use inorganic acids. Among these common inorganic acids, sulfuric acid can severely corrode nickel in the structure, nitric acid can severely corrode tin or tin alloys, and nickel, and hydrochloric acid and fluoric acid have strong permeability and can severely corrode the aluminum layer underneath the chip. These corrosion reactions can have a devastating impact on chip reliability. The present invention uses carboxyl compounds, which have the advantages of minimal damage to metals such as nickel and gold; high protection for aluminum; low lateral corrosion at the copper-nickel junction; low undercutting of copper pillars; stable etching rate over the service life; and high etching uniformity.

[0023] 3. The etching solution of the present invention can greatly reduce the occurrence of the Galvani effect at the copper-nickel junction, has low metal damage to nickel, is insensitive to metallic nickel, and the etching amount at the copper-nickel junction is less than 0.9 μm.

[0024] 4. In the etching solution of the copper-nickel-gold structure, due to the potential difference between the three metals of copper, nickel and gold, the etching solution in the prior art causes relatively large damage to nickel and undercut of copper, which adversely affects the reliability of the substrate. The etching solution of the present invention can reduce the undercut and side cut of copper to below 0.8μm.

[0025] 5. The etching solution of the present invention can ensure the etching rate while also ensuring the etching stability, ensuring that a stable etching rate is maintained within 10 days. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to further explain the beneficial effects of the copper seed layer etching solution of a copper-nickel-gold structure and its application provided in the present invention, corresponding drawings are provided. It should be pointed out that the drawings provided in the present invention are only individual examples selected from all the drawings, and are not intended to be used as a limitation to the claims. All other corresponding maps obtained through the drawings provided in this application should be considered to be within the scope of protection of this application.

[0027] Figure 1 Schematic diagram of the chip structure before gold bump etching.

[0028] Figure 2 This is a schematic diagram of the structure of the chip's copper-nickel-gold bumps before etching.

[0029] Figure 3 This is a schematic diagram of the chip's copper-nickel-gold bump structure after etching.

[0030] Figure 4 This is an electron microscope image of the Galvani phenomenon after etching the copper-nickel-gold bumps on the chip. DETAILED DESCRIPTION

[0031] The present invention can be further understood by referring to the following detailed description of the preferred embodiments of the present invention and the included Examples. Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as those generally understood by those of ordinary skill in the art to which this application belongs. If the definition of a specific term disclosed in the prior art is inconsistent with any definition provided in this application, the definition of the term provided in this application shall prevail.

[0032] As used herein, unless the context clearly indicates otherwise, features that are not limited to the singular or plural form are also intended to include features in the plural form. It should also be understood that, as used herein, the term "prepared by..." is synonymous with "comprising", "including", "including", "having", "including" and / or "comprising", when used in this specification, represents the stated composition, step, method, product or device, but does not exclude the presence or addition of one or more other compositions, steps, methods, products or devices. In addition, when describing the embodiments of the present application, the use of "preferred", "preferably", "more preferred" and the like refers to embodiments of the present invention that may provide certain beneficial effects in certain cases. However, other embodiments may also be preferred under the same circumstances or other circumstances. In addition, the statement of one or more preferred embodiments does not imply that other embodiments are not available, nor is it intended to exclude other embodiments from the scope of the present invention.

[0033] In order to solve the problems existing in the prior art, the present invention provides a copper seed layer etching solution of a copper-nickel-gold structure, wherein the etching solution comprises 5 to 50 wt% of an oxidant, 1 to 40 wt% of a carboxyl compound, 0.01 to 15 wt% of a chelating agent, 0 to 0.01 wt% of an additive, and deionized water. As an example, the weight percentage of the oxidant in the etching solution can be 5%, 8%, 10%, 12%, 15%, 20%, 22%, 25%, 30%, 35%, 40%, 45%, 50%, etc.; as an example, the weight percentage of the carboxyl compound in the etching solution can be 1%, 3%, 5%, 8%, 10%, 12%, 15%, 20%, 22%, 25%, 30%, 35%, 40%, etc.; as an example, the weight percentage of the carboxyl compound in the etching solution can be 1%, 3%, 5%, 8%, 10%, 12%, 15%, 20%, 22%, 25%, 30%, 35%, 40%, etc. For example, the weight percentage of the chelating agent in the etching solution can be 0.01%, 0.05%, 0.1%, 0.2%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, 8%, 10%, 12%, 15%, etc.; as an example, the addition The weight percentage of the agent in the etching solution can be 0.5ppm, 1ppm, 1.2ppm, 1.5ppm, 1.8ppm, 2ppm, 2.5ppm, 2.8ppm, 3ppm, 3.2ppm, 3.5ppm, 3.8ppm, 4ppm, 4.2ppm, 4.5ppm, 4.8ppm, 5ppm, 5.2ppm, 5.5ppm, 5.8ppm, 6ppm, 6.5ppm, 7ppm, 7.5ppm, 8ppm, 8.5ppm, 9ppm, 9.5ppm, 10ppm, 15ppm, 20ppm, 25ppm, 30ppm, 35ppm, 40ppm, 45ppm, 50ppm, 60ppm, 65ppm, 68ppm, 70ppm, 75ppm, 80ppm, 82ppm, 85ppm, 90ppm, 95ppm, 100ppm and the like.

[0034] In some preferred embodiments, the etching solution comprises 5-40 wt% of an oxidant, 1-35 wt% of a carboxyl compound, 0.01-10 wt% of a chelating agent, 0.1-100 ppm of an additive, and deionized water; further preferably, the etching solution comprises 5-45 wt% of an oxidant, 1-35 wt% of a carboxyl compound, 0.1-10 wt% of a chelating agent, 0.1-95 ppm of an additive, and deionized water; further, the etching solution comprises 10-30 wt% of an oxidant, 1-35 wt% of a carboxyl compound, 0.1-8 wt% of a chelating agent, 0.1-95 ppm of an additive, and deionized water.

[0035] In some preferred embodiments, the oxidant is selected from at least one of hydrogen peroxide, potassium persulfate, and sodium persulfate; from the perspective of controllable etching process and improvement of over-etching, it is further preferred that the oxidant is hydrogen peroxide.

[0036] In some preferred embodiments, the carboxyl compound is selected from a mixture of one or more of citric acid, acetic acid, tartaric acid, malic acid, formic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, glycolic acid, acrylic acid, methacrylic acid, lactic acid, gluconic acid, maleic acid, benzoic acid, and salicylic acid; further preferably, the carboxyl compound is selected from a mixture of one or more of citric acid, acetic acid, tartaric acid, malic acid, formic acid, butyric acid, oxalic acid, malonic acid, succinic acid, glycolic acid, acrylic acid, lactic acid, maleic acid, benzoic acid, and salicylic acid; further, the carboxyl compound is selected from a mixture of one or more of acetic acid, citric acid, tartaric acid, tartaric acid, malic acid, oxalic acid, formic acid, acrylic acid, lactic acid, maleic acid, benzoic acid, and salicylic acid.

[0037] In some embodiments, the number of carboxyl compounds is one to five; preferably, the number of carboxyl compounds is at least two, at least three, or at least four; further preferably, the number of carboxyl compounds is one, two, three, or four. The inventors discovered that when the number of carboxyl compounds exceeds five, the etching solution affects the metal etching rate and etching uniformity.

[0038] In some preferred embodiments, when there are at least two carboxyl compounds, one is selected from at least one of acetic acid, oxalic acid, and formic acid, and the other is selected from at least one of malic acid, lactic acid, acrylic acid, tartaric acid, citric acid, benzoic acid, maleic acid, and salicylic acid. The inventors discovered during their research that the etching solution of the present invention containing two or more carboxyl compounds can minimize etching of the copper-nickel junction while maintaining a sufficient etching rate.

[0039] In order to ensure the safety of the etching process and solve the problems of copper undercut and copper residue, in the actual process, the etching time will be increased by 15% on the basis of the general process margin, and in some cases it will even be increased to 100%. This will cause the etched copper metal to have the problem of uneven etching of the etched metal, and the uniformity of the etched metal is generally below 15%. In order to ensure the uniformity of etching, while ensuring the safety of the etching process and solving the problem of etched metal residue, the inventors have found through a large number of experiments that adding a carboxyl compound accounting for 1 to 40wt% of the weight percentage of the etching solution can effectively improve the uniformity of copper etching and the problem of copper residue, while ensuring the safety of the etching process. Under certain conditions, as the acid content increases, the etching rate will accelerate. However, the inventors also found that when the content of the carboxyl compound exceeds 35wt%, the rate will no longer increase, and continuing to increase the acid content will cause excess material, resulting in a cost burden. Therefore, the content of the carboxyl compound is preferably no more than 35wt%. In order to ensure that the etching rate meets the requirements, while ensuring the uniformity of copper etching, solving the problem of copper residue during etching and ensuring the safety of etching, the weight percentage of the carboxyl compound in the etching solution is preferably 1 to 35wt%.

[0040] In some preferred embodiments, the chelating agent is selected from a mixture of one or more of sodium gluconate, sodium citrate, and amino acids; further preferably, the chelating agent is amino acid.

[0041] In some preferred embodiments, the amino acid is selected from a mixture of one or more of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, alanine, glycine, aspartic acid, glutamic acid, sarcosine, L-cysteine, lysine, cysteine, and methionine; further preferably, the amino acid is selected from a mixture of one or more of alanine, glycine, lysine, cysteine, and methionine; further, the amino acid is selected from a mixture of one or more of lysine, cysteine, and methionine.

[0042] The inventors discovered that introducing amino acids into the etching solution can reduce the amount of lateral corrosion of copper bumps. In practice, the inventors further found that when the chelating agent content is within the range of 0.1 to 8% by weight of the etching solution, the amount of lateral etching of the etched copper bumps decreases as the chelating agent content increases. However, when the chelating agent content exceeds 8% by weight of the etching solution, the uniformity of copper etching will be greatly reduced and the occurrence of copper residue will be significantly increased. The inventors have discovered through long-term exploration that when the chelating agent is selected from alanine, glycine, lysine, cysteine, and methionine, the chelating agent can reduce the lateral corrosion of the copper pillar (electroplated copper layer), complex more metal ions, inhibit the decomposition of peroxides, and improve the stability of the etching solution. However, a single amino acid is difficult to meet the very strict production process requirements for undercutting. In view of this, the inventors found that when the chelating agent is selected from alanine, glycine, lysine, cysteine, and methionine at a content of 0.1 to 4 wt%, and at least one amino acid selected from alanine, glycine, lysine, cysteine, and methionine is added to meet the chelating agent content of 1 to 8 wt%, the undercutting of the etching solution is further improved. In addition, the inventors also found that by combining at least two amino acids with at least two carboxyl compounds, the undercutting of the etching solution is greatly improved.

[0043] In some preferred embodiments, the additive is an ionic compound and / or an inorganic acid.

[0044] In some preferred embodiments, the ionic compound is selected from a mixture of one or more of oxides, halides, and bases.

[0045] In some preferred embodiments, the oxide is selected from a mixture of one or more of sodium oxide, manganese oxide, calcium oxide, and magnesium oxide; the halide is selected from a mixture of one or more of copper chloride, ferric chloride, sodium chloride, ammonium chloride, potassium chloride, calcium chloride, copper bromide, ferric bromide, sodium bromide, ammonium bromide, copper iodide, ferric iodide, sodium iodide, ammonium iodide, copper fluoride, ferric fluoride, sodium fluoride, and ammonium fluoride; the inorganic acid is selected from a mixture of one or more of hydrochloric acid, hydrobromic acid, hydroiodic acid, and hydrofluoric acid.

[0046] In some preferred embodiments, the additive is a halide and / or an inorganic acid, wherein the halide is selected from a mixture of one or more of copper chloride, ferric chloride, sodium chloride, ammonium chloride, potassium chloride, calcium chloride, copper fluoride, ferric fluoride, sodium fluoride, and ammonium fluoride, and the inorganic acid is hydrochloric acid and / or hydrofluoric acid.

[0047] The inventors found in their research that the additive can effectively improve the undercut problem of copper. Below 100ppm, the undercut amount will increase with the increase of the additive concentration. In addition, the inventors also found that halogen (fluorine, chlorine, bromine) ions have strong permeability and have a strong affinity with aluminum. Aluminum, as a common electrode of the chip, is very susceptible to corrosion in a chlorine environment. Therefore, when the amount of halogen ion addition is greater than 100ppm, the risk of aluminum damage will be greatly increased. The inventors found in a large number of practices that the halide in the additive is combined with the addition of no more than 50ppm of hydrochloric acid or hydrofluoric acid to effectively improve the undercut problem, while also effectively improving the morphology of the metal after etching, effectively improving the etching uniformity of the metal, and effectively improving the stability of the etching solution.

[0048] The etching solution of the present invention may be prepared by any method known to those skilled in the art, such as physical blending.

[0049] The present invention also provides a use of the copper seed layer etching solution of the copper-nickel-gold structure described above in wafer etching.

[0050] As described in the background art, the copper and titanium layers need to be etched away during the bump production process to provide chip interconnection capabilities while also ensuring their electrical performance. The copper seed layer etching solution of the present invention is the same solution used in wet etching to etch the copper layer in this process.

[0051] In some preferred embodiments, the wafer is a copper-nickel-gold structured wafer.

[0052] Example

[0053] The technical solution of the present invention is described in detail below by way of examples, but the scope of protection of the present invention is not limited to the examples. Unless otherwise specified, the raw materials in the present invention are all commercially available.

[0054] Performance parameter test indicators of the etching composition of the present invention:

[0055] 1. Side etching amount CD loss, such as Figures 2-3 As shown in the figure, the horizontal shrinkage of the electroplated copper before and after copper etching is called the side etching loss (CD loss), and the unit is μm. After etching, the electroplated copper and the copper seed layer must be as flush as possible with the Ni and Au layers to effectively ensure that the Ni layer is not damaged. That is, the side etching at the copper-nickel junction should be as small as possible, and generally the application requirement is less than 1 μm.

[0056] 2. Undercut amount undercut, such as Figures 2-3As shown in the figure, the amount of etching from the junction of the electroplated copper and the copper seed layer into the electroplated copper is the undercut, in μm. After etching, the electroplated copper and the copper seed layer must be as flush with the Ni and Au layers as possible to effectively ensure that the Ni layer is not damaged. That is, the undercut of the electroplated copper layer should be as small as possible, and generally required to be less than 1 μm.

[0057] 3. Uniformity, unit: %, a certain number of points are collected on the wafer (the present invention uses an 8-inch wafer and uniformly collects 49 points) to measure the copper etching thickness X. Uniformity = (X max -X min ) / (2X avg ), where X max 、X min 、X avg They represent the maximum, minimum and average values ​​of etching thickness respectively. The smallest uniformity is the performance value, and the general application requirement is less than 5%.

[0058] 4. Metal corrosion rate, based on nickel and aluminum damage rates, units: The smallest corrosion rate is the performance value, and the general application requires nickel damage to be less than Aluminum damage is less than

[0059] 5. Etching rate stability, unit: day, for the initial seed layer etching rate is The etching rate is tested every 12 hours. Afterwards, it was determined that the etching solution was ineffective.

[0060] Examples 1 to 18 and Comparative Examples 1 to 4 all provide an etching composition, and the components in each example are shown in Table 1. The etching composition is prepared by physical blending.

[0061] Table 1

[0062]

[0063]

[0064] Performance test results

[0065] The etching solutions obtained in Examples 1 to 18 and Comparative Examples 1 to 4 were subjected to performance tests. The test contents included CD loss, undercut, uniformity, metal corrosion rate, and etching rate stability. The test results are shown in Table 2.

[0066] To ensure the parallel implementation of the implementation plan and the comparison plan, the experimental process uses the following Figure 1 The wafer with the structure shown (the thickness of the Cu seed layer of the experimental wafer is ) to conduct the immersion experiment of the medicine solution. The experimental temperature is constantly controlled at 25℃.

[0067] In addition, while maintaining the same experimental method, it should be noted that the factors affecting the CD and undercut values ​​are the formulation composition and the overcut amount. Here, according to the usual practice of the formulation, the overcut amount is 100% as the background condition for the experiment. The overcut amount described in this application is the background condition for the experiment, in %, and the overcut amount = (t-t0) / t0, where t0 is the time it takes for the copper surface to be completely corroded, and t is the actual corrosion time.

[0068] Table 2

[0069]

[0070]

[0071] By comparing Examples 1 and 2 with Examples 1 and 2, it can be seen that the oxidant hydrogen peroxide provided by the present invention performs better than sodium persulfate, and the carboxyl compound performs better than phosphoric acid, which can effectively reduce the lateral corrosion and undercut amount, nickel and aluminum damage data, and improve the uniformity performance; by comparing Comparative Example 3 with Example 3, it can be seen that the chelating agent provided by the present invention can effectively reduce the lateral corrosion and undercut value, nickel and aluminum damage data, and improve the uniformity performance; by comparing Comparative Example 4 with Example 4, it can be seen that the additive halogen ion provided by the present invention can effectively reduce the lateral corrosion and undercut value, nickel and aluminum damage data, and improve the uniformity performance; by comparing Examples 2 and 6, it can be seen that the carboxyl compound used in the present invention can be lactic acid, tartaric acid, etc. By Examples 3 and 7, it can be seen that the chelating agent has basically the same effect at a certain concentration. By Examples 4 and 8, as the amount of additive added increases, the lateral corrosion amount and undercut tend to increase. By Examples 9 to 14, it is confirmed that the carboxyl compound can be used in combination.

[0072] The foregoing examples are merely illustrative and serve to illustrate some of the features of the method of the present invention. The appended claims are intended to claim the widest possible scope that can be envisioned, and the embodiments presented herein are merely illustrative of selected implementations according to a combination of all possible embodiments. Therefore, it is the applicant's intention that the appended claims are not limited by the selection of examples illustrating the features of the present invention. Some numerical ranges used in the claims also include subranges therein, and variations in these ranges should also be interpreted as being covered by the appended claims where possible.

Claims

1. A copper seed layer etching solution of a copper-nickel-gold structure, characterized in that: The etching solution comprises, by weight percentage, 5 to 50 wt% of an oxidant, 8 to 35 wt% of a carboxyl compound, 0.01 to 15 wt% of a chelating agent, 0.5 to 50 ppm of an additive, and deionized water. The carboxyl compound is selected from a mixture of one or more of citric acid, acetic acid, tartaric acid, malic acid, formic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, glycolic acid, acrylic acid, methacrylic acid, lactic acid, gluconic acid, maleic acid, benzoic acid, and salicylic acid; There are at least two types of the carboxyl compounds, one of which is selected from at least one of acetic acid, oxalic acid, and formic acid, and the other is selected from at least one of malic acid, lactic acid, acrylic acid, tartaric acid, citric acid, benzoic acid, maleic acid, and salicylic acid; The chelating agent comprises at least two different kinds, one of the chelating agents is selected from alanine, glycine, lysine, cysteine, and methionine and its content is 0.1wt% to 4wt%, and the remaining at least one chelating agent is selected from alanine, glycine, lysine, cysteine, and methionine and its content is 1wt% to 8wt%; The additive is a halide, wherein the halide is selected from a mixture of one or more of copper chloride, iron chloride, sodium chloride, ammonium chloride, potassium chloride, calcium chloride, copper fluoride, iron fluoride, sodium fluoride, and ammonium fluoride.

2. The copper seed layer etching solution of the copper-nickel-gold structure according to claim 1, characterized in that The oxidant is selected from at least one of hydrogen peroxide, potassium persulfate, and sodium persulfate.

3. Use of the copper seed layer etching solution of the copper-nickel-gold structure according to any one of claims 1 to 2 in wafer etching.

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