Copper metal etching liquid composition

Abstract

The invention relates to the technical field of etching liquid, in particular to a copper metal etching liquid composition. Comprising the following components in percentage by weight: 5-10% of hydrogen peroxide, 0.1-0.3% of a first fluorine source, 1-5% of first inorganic acid, 1-5% of alkali, 0.01-0.8% of a first metal corrosion inhibitor and the balance of deionized water; and the auxiliary agent comprises 2-8% of a second fluorine source, 10-55% of second inorganic acid, 0.1-2% of a second metal corrosion inhibitor and the balance of deionized water. The etching liquid is excellent in etching effect, CD-loss reaches 0.6-0.8 [mu] m, the slope angle reaches 40-50 degrees, the highest copper load reaches 20000 ppm, and meanwhile the problem that when copper is high, due to the fact that the nitric acid concentration is too high, metal etching is abnormal is solved.

Description

Technical Field

[0001] This invention relates to the field of etching solution technology, and more specifically, to a copper metal etching solution composition. Background Technology

[0002] Circuit board etching solution is one of the core materials in the fabrication of display devices. Its performance directly determines the precision and quality of the metal wiring on the circuit board. Especially in the etching process of single or multiple layers of titanium / copper metal, the selectivity, stability, and etching effect of the etching solution are crucial to the integrity of the circuit pattern. Currently, circuit boards commonly contain multilayer film structures of metals such as titanium and copper. The etching solution is usually composed of components such as oxidants, complexing agents, corrosion inhibitors, and buffers. It needs to achieve precise etching of the target metal layer while avoiding problems such as over-etching and side etching. Etching solutions in the industry generally face multiple technical challenges: First, insufficient etching uniformity, leading to problems such as cone angle deviation and severe lateral etching, affecting the image accuracy of fine wires; second, the accumulation of metal ions causes premature failure of the etching solution, with conventional etching solutions having a copper load of only 10,000 ppm, which easily results in uneven etching under high copper conditions; third, some systems rely on hydrogen peroxide, which has a high decomposition rate, reducing process stability. As products such as thin-film transistor liquid crystal display panels develop towards higher precision and higher reliability, there is an urgent need to develop a titanium / copper metal layer selective etching solution that provides uniform and stable etching, excellent control over lateral etching and cone angle, smooth and residue-free metal lines, stable performance under high copper load, and long service life, in order to overcome existing technical bottlenecks and meet the high-quality requirements of circuit board manufacturing.

[0003] The etching composition disclosed in Chinese invention patent application CN107475715A achieves highly selective etching of single films or copper-based bimetallic films by adding hydrogen peroxide stabilizers, which inhibits the decomposition of hydrogen peroxide to a certain extent. However, it does not fundamentally solve the inherent defect of easy decomposition of hydrogen peroxide, and the problem of unstable etching rate still exists after long-term use. Summary of the Invention

[0004] This invention provides a copper metal etching solution composition, comprising a main agent and an auxiliary agent. By weight percentage, the main agent comprises 5-10% hydrogen peroxide, 0.1-0.3% of a first fluorine source, 1-5% of a first inorganic acid, 1-5% of an alkali, 0.01-0.8% of a first metal corrosion inhibitor, with deionized water to make up the balance. The auxiliary agent comprises 2-8% of a second fluorine source, 10-55% of a second inorganic acid, 0.1-2% of a second metal corrosion inhibitor, with deionized water to make up the balance.

[0005] Optionally, by weight percentage, the main agent comprises 6-8% hydrogen peroxide, 0.1-0.3% of a first fluorine source, 2-5% of a first inorganic acid, 1-3% of an alkali, 0.1-0.8% of a first metal corrosion inhibitor, with deionized water to make up the balance; the auxiliary agent comprises 2-5% of a second fluorine source, 25-55% of a second inorganic acid, 0.5-1% of a second metal corrosion inhibitor, with deionized water to make up the balance.

[0006] The first metal corrosion inhibitor and the second metal corrosion inhibitor both include at least one of the following compounds: 5-aminotetrazole, 1,2,4-triazole, 6-aminopurine, and 5-methyltetrazole.

[0007] Both the first and second metal corrosion inhibitors include 5-aminotetrazolium.

[0008] Optionally, the first metal corrosion inhibitor includes 5-aminotetrazole, 1,2,4-triazole, and 6-aminopurine.

[0009] Optionally, the weight ratio of 5-aminotetrazole, 1,2,4-triazole and 6-aminopurine is (0.3-0.4):(0.15-0.2):(0.08-0.1).

[0010] The second metal corrosion inhibitor comprises 5-aminotetrazole and 6-aminopurine.

[0011] Optionally, the content of 5-aminotetrazole in the excipient is 0.1-0.5 wt%.

[0012] Optionally, the content of 5-aminotetrazole in the excipient is 0.16-0.5 wt%.

[0013] This study found that by limiting the content of 5-aminotetrazole in the excipient to 0.1-0.5 wt%, abnormal metal etching caused by high concentrations of inorganic acids under high copper loading can be avoided. Under high copper loading, the large amount of Cu²⁺ accumulated in the etching solution will catalyze the oxidation reaction of high concentrations of inorganic acids, causing a surge and uneven etching rate. At the same time, the strong oxidizing and acidic properties of high acid will destroy the stability of the etching interface. Cu²⁺ is also prone to forming unstable complexes with acid radicals, further aggravating the uneven etching. However, the nitrogen heterocyclic structure of 5-aminotetrazole at this content can selectively adsorb onto the copper metal surface through lone pair electrons. It forms a dense protective film, inhibiting excessive oxidation of metals by high inorganic acids and preventing excessively rapid local etching. The amino and nitrogen heterocycles in the molecule can complex free Cu²⁺, reducing its catalytic effect on inorganic acid reactions and preventing the deposition of Cu²⁺ and acid radicals. At the same time, the content of 0.1-0.5wt% can balance corrosion inhibition and etching efficiency, ensuring both the suppression of abnormalities and preventing the etching rate from being too low. Ultimately, the etching solution can still achieve stable etching under high copper load (such as CD-loss of 0.6-0.8μm and slope angle of 40-50°), solving the etching abnormality problem caused by high copper and high inorganic acid.

[0014] The first fluorine source and the second fluorine source are both selected from at least one of hydrofluoric acid, ammonium bifluoride, and ammonium fluoride.

[0015] The first inorganic acid and the second inorganic acid are both selected from at least one of nitric acid, phosphoric acid, and sulfuric acid.

[0016] The content of the first inorganic acid in the main agent is 2-4 wt%.

[0017] Optionally, the content of the first inorganic acid in the main agent is 2.5-3 wt%.

[0018] The weight ratio of hydrogen peroxide to the first fluorine source is (5-8):0.2.

[0019] Optionally, the weight ratio of the hydrogen peroxide to the first fluorine source is (6-8):0.2.

[0020] The preparation method of the copper metal etching solution composition involves mixing the main agent and auxiliary agent components evenly and setting them aside for later use.

[0021] Beneficial effects 1. All raw materials used in this invention are inexpensive and readily available, and constitute a small proportion of the medicinal liquid, effectively reducing production costs.

[0022] 2. By specifying that the first metal corrosion inhibitor simultaneously contains 5-aminotetrazole, 1,2,4-triazole and 6-aminopurine, abnormal metal etching caused by high concentrations of inorganic acid can be avoided when copper is high.

[0023] 3. The etching solution prepared by this invention can achieve a maximum copper loading of 20,000 ppm.

[0024] 4. Compared with the conventional molybdenum-containing etching solution with a high copper decomposition rate of 0.3-0.4% / h, the etching solution of the present invention has a hydrogen peroxide decomposition rate of <0.05% / h at the end of the etching process, which can improve etching safety.

[0025] 5. The etching solution of this invention has excellent etching effect, with a CD-loss of 0.6-0.8μm and a slope angle of 40-50°. Attached Figure Description

[0026] Figure 1 This is an electron microscope image of the etching solution after etching in Example 1.

[0027] Figure 2 This is an electron microscope image of the etching solution after etching in Example 2.

[0028] Figure 3 This is an electron microscope image of the etching solution after etching in Example 3.

[0029] Figure 4 This is an electron microscope image of the etching solution after etching, as shown in Comparative Example 1.

[0030] Figure 5 This is an electron microscope image of the etching solution after etching, as shown in Comparative Example 2. Detailed Implementation

[0031] Example 1 A copper metal etching solution composition, consisting of a main agent and an auxiliary agent, the components of which are shown in Table 1 by weight percentage, where blank spaces indicate no addition.

[0032] Table 1

[0033] The preparation method of the copper metal etching solution composition involves mixing the main agent and auxiliary agent components evenly and setting them aside for later use.

[0034] Performance testing methods and data The etching solutions prepared in the examples and comparative examples were subjected to performance tests. The test data are listed in Table 2, where blank spaces indicate poor etching effect and no test was conducted.

[0035] The etching conditions are as follows: copper film thickness: 6000 Å; molybdenum-niobium alloy film thickness: 200 Å; auxiliary agent addition method: for every 1000 ppm increase in copper ions, add 1.4% of the main agent weight of auxiliary agent to the system; etching temperature: 30℃; etching time: 150s.

[0036] Table 2

[0037] As shown in Table 2, combined with Figure 1-3 It can be seen that: the etching effect of the example is excellent, with a CD-loss of 0.6-0.8μm, a slope angle of 40-50°, and a maximum copper load of 20000ppm; comparative example 3 shows a chamfer; combined with Figure 4-5 The results show that the etching solution used in Comparative Examples 1-2 was not uniformly etched.

Claims

1. A copper metal etching liquid composition characterized by comprising: The main agent comprises, by weight percentage, 5-10% of hydrogen peroxide, 0.1-0.3% of a first fluorine source, 1-5% of a first inorganic acid, 1-5% of a base, 0.01-0.8% of a first metal corrosion inhibitor, and deionized water to make up the balance; and the auxiliary agent comprises 2-8% of a second fluorine source, 10-55% of a second inorganic acid, 0.1-2% of a second metal corrosion inhibitor, and deionized water to make up the balance.

2. The copper metal etching liquid composition according to claim 1, characterized by, The main agent comprises, by weight percentage, 6-8% of hydrogen peroxide, 0.1-0.3% of a first fluorine source, 2-5% of a first inorganic acid, 1-3% of a base, 0.1-0.8% of a first metal corrosion inhibitor, and deionized water to make up the balance; and the auxiliary agent comprises 2-5% of a second fluorine source, 25-55% of a second inorganic acid, 0.5-1% of a second metal corrosion inhibitor, and deionized water to make up the balance.

3. The copper metal etching liquid composition according to claim 2, wherein The first metal corrosion inhibitor and the second metal corrosion inhibitor each comprises at least one of the following compounds: 5-amino tetrazole, 1,2,4-triazole, 6-amino purine, and 5-methyl tetrazole.

4. The copper metal etching liquid composition according to claim 3, wherein The first metal corrosion inhibitor comprises 5-amino tetrazole, 1,2,4-triazole, and 6-amino purine.

5. The copper metal etching liquid composition according to claim 4, wherein The second metal corrosion inhibitor comprises 5-amino tetrazole and 6-amino purine.

6. The copper metal etching liquid composition according to any one of claims 3 to 5, characterized by, The content of 5-amino tetrazole in the auxiliary agent is 0.1-0.5wt%.

7. The copper metal etching liquid composition according to claim 1, wherein The first fluorine source and the second fluorine source are each selected from at least one of the following: hydrofluoric acid, ammonium bifluoride, and ammonium fluoride.

8. The copper metal etching liquid composition according to claim 1, wherein The first inorganic acid and the second inorganic acid are each selected from at least one of the following: nitric acid, phosphoric acid, and sulfuric acid.

9. The copper metal etching liquid composition according to claim 1, wherein The content of the first inorganic acid in the main agent is 2.5-3wt%.

10. The copper metal etching liquid composition according to claim 1, wherein The weight ratio of the hydrogen peroxide to the first fluorine source is (6-8):0.2.

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