A small critical dimension bias copper etching solution composition

Abstract

The present application relates to etching liquid technical field, specifically to a kind of small key size deviation copper etching liquid composition, by mass percentage, including the following components: hydrogen peroxide, ammonium hydrogen fluoride, 2-mercapto-1,3,4-thiadiazole, imidazole, citric acid, malic acid, ammonium sulfate, triethylene glycol, the rest is deionized water.The mass ratio of 2-mercapto-1,3,4-thiadiazole and imidazole is controlled between 1-2 in the present application, and a complementary adsorption layer is formed, wherein imidazole provides basic corrosion inhibition by covering quickly, 2-mercapto-1,3,4-thiadiazole enhances inhibition by strong bonding, and dynamic protection is achieved by the synergistic effect of the two, which can control the rate, improve uniformity and obtain a bright surface;At the same time, strong inhibition side etching, accurate control of etching morphology, especially anisotropy, to obtain steep sidewall and smooth surface;It can meet the etching demand of small CD bias.

Description

Technical Field

[0001] This invention relates to the field of etching solution technology, specifically to a copper etching solution composition with small critical dimension deviations. Background Technology

[0002] With the rapid development of display technology, TFT-LCD panels (thin-film transistor liquid crystal displays) are constantly evolving towards larger sizes, higher resolutions, and lower power consumption, leading to increasingly fierce industry competition and ever-more stringent requirements for manufacturing process precision. Against this backdrop, controlling CD bias (critical dimension deviation) has become a key process indicator determining panel performance, yield, and display quality. Especially with the adoption of low-resistance metal wiring such as copper / titanium, the etching and alignment requirements for fine patterns have further increased. Excessive CD bias affects the alignment accuracy of multiple film layers, reduces aperture ratio, and increases the risk of short circuits, directly restricting yield and display uniformity. Simultaneously, strict CD bias control provides a technological foundation for narrow bezel designs and high refresh rate panels. Therefore, low CD bias is not only a core indicator of current high-precision manufacturing but also a crucial guarantee for the continuous evolution of TFT-LCD technology towards higher performance, playing a key role in enhancing product competitiveness and driving industry progress. Based on this, a copper etching solution composition for low critical dimension deviation is proposed. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a copper etching solution composition with small critical size deviations. This invention strictly controls the mass ratio of 2-mercapto-1,3,4-thiadiazole and imidazole to be between 1 and 2, forming a complementary adsorption layer. The imidazole provides basic etching inhibition through rapid coverage, while the strong bonding of 2-mercapto-1,3,4-thiadiazole enhances the inhibition, thus meeting the etching requirements for small CDbias.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a copper etching solution composition for small critical size deviations, comprising the following components by mass percentage: 10-12% hydrogen peroxide, 0.01-0.03% ammonium bifluoride, 0.3-0.6% 2-mercapto-1,3,4-thiadiazole, 0.1-0.3% imidazole, 2-4% citric acid, 1.5-3% malic acid, 0.3-0.5% ammonium sulfate, 3-5% triethylene glycol, with the balance being deionized water.

[0005] Preferably, the mass ratio of 2-mercapto-1,3,4-thiadiazole to imidazole is x, where 1 < x < 2.

[0006] Preferably, the copper etching solution composition is used to etch a composite metal film containing copper and molybdenum.

[0007] Preferably, the composite metal film is a copper / molybdenum-titanium alloy bilayer structure film.

[0008] Preferably, the etching method of the copper etching solution composition is spray etching, and the spray pressure is 0.1-0.2 MPa.

[0009] Preferably, the etching temperature of the copper etching solution composition is 30°C.

[0010] Preferably, the copper etching solution composition has an over-etching time of 35% of the main etching time during etching.

[0011] This invention provides a copper etching solution composition with small critical dimension deviations, which has the following advantages compared with the prior art:

[0012] This invention strictly controls the mass ratio of 2-mercapto-1,3,4-thiadiazole and imidazole to between 1 and 2, forming a complementary adsorption layer. The imidazole provides basic corrosion inhibition through rapid coverage, while the strong bonding of 2-mercapto-1,3,4-thiadiazole enhances the inhibition. The two work synergistically to achieve dynamic protection, which can control the etching rate, improve uniformity, and obtain a bright surface. At the same time, it strongly inhibits side etching and precisely controls the etching morphology (especially anisotropy), thereby obtaining steep sidewalls and a smooth surface. It can meet the etching requirements for small CD bias.

[0013] The copper etching solution composition of this invention has a low hydrogen peroxide content, which helps to improve process control precision, achieve more uniform etching and less side etching, making it suitable for fine circuits; it enhances process stability and safety, reduces the risk of exothermic reactions and ineffective decomposition of hydrogen peroxide; it improves compatibility with masks and equipment; and it reduces raw material costs and subsequent environmental treatment pressure. The combined use of citric acid and malic acid acts as a good chelating agent, forming a stable and soluble complex with copper ions to remove reaction products from the metal surface, driving the etching reaction to continue. Both also provide and maintain the acidic pH environment required for the reaction. The triethylene glycol used has a certain complexing ability, forming a weak coordination with copper ions, assisting the main complexing agent in stabilizing copper ions in the etching solution, reducing precipitation or crystallization, and extending the service life of the etching solution. Attached Figure Description

[0014] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0015] Figure 1 This is an electron microscope image of the substrate after etching using the first group of copper etching solution compositions in N-1 of the present invention;

[0016] Figure 2 This is an electron microscope image of the substrate after etching using the copper etching solution composition of group N-1 in this invention;

[0017] Figure 3 This is an electron microscope image of the substrate after etching using the copper etching solution composition in A-1 of the present invention;

[0018] Figure 4 This is an electron microscope image of the substrate after etching using the copper etching solution composition in A-2 of this invention;

[0019] Figure 5 This is an electron microscope image of the substrate after etching using the copper etching solution composition in A-3 of this invention;

[0020] Figure 6 This is an electron microscope image of the substrate after etching using the copper etching solution composition in A-4 of this invention;

[0021] Figure 7 This is an electron microscope image of the substrate after etching using the copper etching solution composition in A-5 of this invention;

[0022] Figure 8 This is an electron microscope image of the substrate after etching using the copper etching solution composition in A-6 of this invention;

[0023] Figure 9 The images shown are electron microscope (EM) images of the substrates after etching with two copper etching solution compositions at O / E 10%, O / E 20%, and O / E 30% in N-1 of this invention.

[0024] Figure 10 The images shown are electron microscope (EM) images of the substrates after etching with two copper etching solution compositions at O / E 35%, O / E 40%, and O / E 50% in N-1 of this invention. Detailed Implementation

[0025] The following embodiments are provided to illustrate the implementation of this application in detail, so that the process of how this application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0026] Abbreviations in this invention:

[0027] Hydrogen peroxide (H2O2); Ammonium hydrogen fluoride (ABF); 2-Mercapto-1,3,4-thiadiazole (MTZ); Imidazole; Citric acid (CA); Malic acid (MA); Ammonium sulfate (AS); Triethylene glycol (TEG); Deionized water (DIW); Copper / Molybdenum Titanium Alloy (Cu / MTD).

[0028] S / E – Distance from the end of the PR (photoresist) to the metal end; Tail – Length of the metal end protrusion; T / A – Angle formed by the upper and lower metal layers; Residue – Residue; O / E – Over-etching rate; CD bias – Critical dimension deviation.

[0029] Example

[0030] According to Table 1, different components of the small critical dimension deviation copper etching solution composition N-1, A-1, A-2, A-3, A-4, A-5, A-6 are set.

[0031] Table 1 Copper Etching Solution Composition

[0032]

[0033] Performance testing was conducted on the copper etching solution compositions N-1, A-1, A-2, A-3, A-4, A-5, and A-6: etching tests were performed using a substrate with Cu / MTD=2500 / 200Å as the test material.

[0034] The etching method is as follows: spray etching is performed at 30℃, with the spray pressure controlled at 0.1 MPa and the etching time controlled at 35% over-etching. The specific test results are shown in Table 2.

[0035] Table 2 Etching Results

[0036]

[0037] Table 2 shows that under the same testing conditions, a smaller S / E is better, which aligns with the future trend of smaller CD bias (critical dimension deviation). Compared to N-1, A-1 has a larger S / E and residual defects; although A-2's S / E is close to N-1, it also has residual defects; A-3 has a Tail of -0.05 and A-4 has a Tail of -0.02, indicating severe undercutting problems, which is a poor lateral erosion; although A-5 and A-6 do not have residual defects, their S / E is relatively large.

[0038] The determination of O / E 35% in this invention is shown in Table 3. Taking the N-1 formulation as an example, two groups were set up for testing.

[0039] Table 3 Etching Results

[0040]

[0041] As shown in Table 3, N-1 has residue problems at O / E 10%, O / E 20% and O / E 30%, which will lead to product defects; at O / E 40% and O / E 50%, although there are no residue problems, the S / E is too high; in the first group with O / E 35%, the S / E is the smallest and the performance is the best.

[0042] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A copper etching solution composition with small critical dimension deviations, characterized in that, By mass percentage, it comprises the following components: 10-12% hydrogen peroxide, 0.01-0.03% ammonium bifluoride, 0.3-0.6% 2-mercapto-1,3,4-thiadiazole, 0.1-0.3% imidazole, 2-4% citric acid, 1.5-3% malic acid, 0.3-0.5% ammonium sulfate, 3-5% triethylene glycol, with the balance being deionized water; The mass ratio of 2-mercapto-1,3,4-thiadiazole to imidazole is x, where 1 < x < 2; The copper etching solution composition is used to etch a composite metal film containing copper and molybdenum; During etching, the copper etching solution composition has an over-etching time of 35% of the main etching time.

2. The copper etching solution composition with small critical dimension deviations according to claim 1, characterized in that, The composite metal film is a copper / molybdenum-titanium alloy double-layer structure film.

3. The copper etching solution composition with small critical dimension deviations according to claim 1, characterized in that, The etching method of the copper etching solution composition is spray etching, and the spray pressure is 0.1-0.2 MPa.

4. The copper etching solution composition with small critical dimension deviations according to claim 1, characterized in that, The etching temperature of the copper etching solution composition is 30°C.

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