Etching solution composition

Abstract

The invention relates to the technical field of wet etching, in particular to an etching liquid composition capable of being used for etching copper-molybdenum and alloy films thereof. The etching liquid composition provided by the invention comprises hydrogen peroxide, a first metal ion chelating agent, a second metal ion chelating agent, a third metal ion chelating agent, inorganic alkali, an etching inhibitor, fluoride and water, the first metal ion chelating agent, the second metal ion chelating agent, the third metal ion chelating agent and the fluoride meet the following relational expression: # imgabs0. According to the etching solution composition disclosed by the invention, the decomposition rate of H2O2 can be well controlled in a high hydrogen peroxide system through mutual coordination of the three metal ion chelating agents; the stability and the service life of the etching liquid are improved; when the etching liquid is applied to etching of a metal film, the line width loss is small, line breakage and residues are avoided, the compatibility is good, the etching performance of the etching liquid on a metal layer is well improved, and the uniformity and the stability of metal layer etching are better.

Description

Technical Field

[0001] The invention relates to the technical field of wet etching, and in particular to an etching liquid composition that can be used for etching copper, molybdenum and alloy films thereof. Background Art

[0002] In the process of forming microcircuits in the internal structures of semiconductor devices, thin film transistor liquid crystal displays (TFT-LCD), organic light emitting diodes (OLED), etc., a series of processes such as film formation, coating, exposure, development, etching, and stripping are usually required. Among them, etching is mainly divided into two modes: wet etching and dry etching. Due to the advantages of high etching efficiency, good etching accuracy, and low cost, wet etching has attracted more and more attention.

[0003] In the existing panel design system, it is one of the mainstream trends to design circuits with low-resistance copper and its alloys as the main components. However, since the adhesion between copper and glass substrate is often poor, people usually choose some inert metals (such as molybdenum, titanium, niobium, etc.) that have good adhesion to the glass plate and can block diffusion to improve this phenomenon. Therefore, metal wiring usually has two, three or even more different metal layer structures.

[0004] However, with the gradual enlargement and high resolution of liquid crystal displays, the design of microscopic circuit structures has become more and more complicated. In order to ensure the firmness of metal wiring and improve the performance and yield of products, the thickness of the inert metal layer has become thicker and thicker, which increases the difficulty of etching itself. On the other hand, as the density of metal wiring is getting higher and higher, and the line width design is getting narrower and narrower, this requires a small etching deviation (i.e., lateral etching loss, CD Loss), so it is very easy to have problems such as etching disconnection or residue in the actual etching process. In order to improve these problems, we usually need to add higher concentrations of hydrogen peroxide. However, the stability of the etching solution under the high concentration hydrogen peroxide system (including the etching solution itself and the etching performance) is often poor, and the etching life is not ideal. Repeated replacement of new solution will inevitably lead to increased costs. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides an etching solution composition, which improves the stability and life of the etching solution while ensuring the etching performance, which is beneficial to improving the yield of display device product production.

[0006] The present invention adopts the following technical solutions:

[0007] An etching liquid composition, comprising hydrogen peroxide, a first metal ion chelating agent, a second metal ion chelating agent, a third metal ion chelating agent, an inorganic base, an etching inhibitor, a fluoride and water;

[0008] The first metal ion chelating agent is a compound containing both amino and carboxyl coordination groups in its molecular structure;

[0009] The second metal ion chelating agent is a compound containing both hydroxyl and carboxyl coordination groups in its molecular structure;

[0010] The third metal ion chelating agent is a compound containing a sulfonic acid coordination group in its molecular structure;

[0011] The first metal ion chelating agent, the second metal ion chelating agent, the third metal ion chelating agent, and the fluoride satisfy the following relationship:

[0012]

[0013] Wherein, according to the total weight of the etching solution composition:

[0014] A is the content of the first metal ion chelating agent, in %;

[0015] a is the number of imino groups, secondary amino groups and carboxyl groups in the first metal ion chelating agent;

[0016] B is the content of the second metal ion chelating agent, in %;

[0017] b is the number of hydroxyl groups and carboxyl groups in the second metal ion chelating agent;

[0018] C is the content of the third metal ion chelating agent, in %;

[0019] c is the number of sulfonic acid groups in the third metal ion chelating agent;

[0020] D is the content of the fluoride, in %.

[0021] Furthermore, among the first metal ion chelating agent, the second metal ion chelating agent and the third metal ion chelating agent, 2≤a≤10, 2≤b≤6, 1≤c≤3; preferably, 3≤a≤8, 2≤b≤4, 1≤c≤2.

[0022] Preferably, the first metal ion chelating agent, the second metal ion chelating agent, the third metal ion chelating agent, and the fluoride satisfy the following relationship:

[0023] 200≤S≤1800.

[0024] During the use of etching solution, H 2 O 2As the main oxidant, it will continuously oxidize the metal and its alloy into oxidized substances, and then dissolve these oxides with acid to obtain free metal ions. These free metal ions then form stable chelates with chelating agents and are stored in the etching solution, thereby greatly reducing H 2 O 2 decomposition rate. At the same time, the selected chelating agents are all organic acids containing at least one carboxyl group or sulfonic acid group, which have a good pH buffering effect. As the etching process proceeds, it can further ensure that the pH fluctuation of the etching solution is small and the etching stability is good. Studies have found that although too much first and second metal ion chelating agents can improve the sudden boiling, it will seriously inhibit the etching rate of the inert metal, and the third metal ion chelating agent can also chelate metal ions well and can increase the etching rate of the copper layer, but it has basically no effect on the etching of the inert metal layer, so it is very easy to have poor etching such as residue. Therefore, people usually introduce fluoride to solve the residue problem, and fluoride has a greater effect on the precipitation of the etching solution. Therefore, the applicant took the above factors into consideration when developing the etching solution. After extensive research, it was found that when 100≤S≤2000, even with the increase in the amount of dissolved copper, the stability of the etching solution is very good. The smaller the fluctuation value of the etching deviation (i.e., lateral etching loss, CD Loss) and the etching cone angle (TaperAngle), the less residue and precipitate can be ensured. At the same time, the synergistic effect of the three chelating agents also ensures that the sudden boiling time of the etching solution can reach more than 48 hours.

[0025] When S is less than 100, that is, the value of (A×a+5B×b+20C×c) is too small or the value of D is too large, that is, the content of metal ion chelating agent is too little or the content of fluoride is too much; this will lead to incomplete chelation of metal ions by the etching solution, resulting in H 2 O 2 Rapid decomposition and large pH fluctuations will eventually lead to poor stability of etching parameters and reduced service life; and excessive fluoride may also cause precipitation and undercutting, causing serious damage to silicon-based materials. The formed fluorosilicate may precipitate in the form of precipitation, which is not conducive to actual production.

[0026] When S>2000, that is, the value of (A×a+5B×b+20C×c) is too large or the value of D is too small, that is, the content of metal ion chelate is too much or the content of fluoride is too little; this will greatly limit the etching rate of the inert metal layer, increase the time cost of factory use; and the lack of fluoride is prone to bottom residue and other phenomena. In addition, too much metal ion chelate may gradually form precipitates due to solubility limitations.

[0027] Furthermore, based on the total weight of the etching solution composition, it contains 10% to 25% of hydrogen peroxide, 1% to 5% of a first metal ion chelating agent, 0.1% to 2% of a second metal ion chelating agent, 0.1% to 1% of a third metal ion chelating agent, 0.1% to 2% of an inorganic base, 0.005% to 0.1% of an etching inhibitor and 0.01 to 0.10% of a fluoride, and the balance is water.

[0028] Furthermore, the first metal ion chelating agent is a compound containing both amino and carboxyl coordination groups in its molecular structure;

[0029] Preferably, the first metal ion chelating agent is at least one of iminodiacetic acid, nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), aminotri(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid) and salts thereof;

[0030] The first metal ion chelating agent is mainly used to chelate copper and molybdenum alloy metal ions, and improves the stability of the etching solution itself by controlling the decomposition rate of hydrogen peroxide. When the content of the first metal ion chelating agent is less than 1%, it cannot effectively chelate more metal ions; and when the content is higher than 5%, it will greatly reduce the etching rate of the etching solution on the underlying molybdenum alloy, resulting in the etching parameters failing to meet the requirements.

[0031] The second metal ion chelating agent is a compound containing both hydroxyl and carboxyl coordination groups in its molecular structure;

[0032] Preferably, the second metal ion chelator is at least one of citric acid, malic acid, succinic acid, glycolic acid, tartaric acid and gluconic acid;

[0033] In the etching solution of the present invention, the chelating performance of the second metal ion chelating agent is weaker than that of the first metal ion chelating agent. As the etching process proceeds, the metal ions in the etching solution increase, the first metal ion chelating agent is gradually consumed, and the second metal ion chelating agent begins to play a role in the later stage of the etching process to ensure the stability of the system. When the content of the second metal ion chelating agent exceeds 2%, its inhibitory effect on the metal layer is obvious, and the etching rate cannot meet the requirements.

[0034] The third metal ion chelating agent is a compound containing a sulfonic acid coordination group in its molecular structure;

[0035] Preferably, the third metal ion chelating agent is at least one of hydroxyethyl sulfonic acid, methanesulfonic acid, aminosulfonic acid, phenolsulfonic acid, and methanedisulfonic acid;

[0036] The third metal ion chelating agent has the weakest chelating performance and is mainly used to capture metal ions that are not chelated by the first and second metal ion chelating agents, further reducing their catalytic activity. It mainly starts to play a role in the later stage of the etching process. At the same time, since the third metal ion chelating agent also has strong acidity, it can well regulate the etching rate of the etching solution on the metal. When the content of the third metal ion chelating agent exceeds 1%, the pH of the etching solution will be very low, the etching cone angle will be difficult to control, and a large amount of precipitates will appear at the bottom.

[0037] The present invention can well ensure the uniformity and stability of the etching process through the synergistic effect of the above three metal ion chelating agents; can effectively and accurately control the etching cone angle and etching deviation, and reduce the fluctuation range of characteristic parameters in the entire etching process.

[0038] Furthermore, the etching inhibitor is a heterocyclic compound containing one or more nitrogen atoms or sulfur atoms in its molecular structure; it can achieve precise control of etching deviation and etching cone angle in a higher hydrogen peroxide system.

[0039] Preferably, the etching inhibitor is at least one of 5-aminotetrazolyl, 5-methyltriazole, 1,2,4-triazole, benzotriazole, methylbenzotriazole, carboxybenzotriazole, 2-aminothiazole, cytosine and thymine.

[0040] Furthermore, the inorganic base is at least one of sodium hydroxide and potassium hydroxide.

[0041] Furthermore, the fluoride is at least one of ammonium bifluoride, hydrofluoric acid, fluoroboric acid, sodium fluoroborate, potassium fluoroborate and ammonium fluoroborate. Fluoride can directly react with molybdenum alloy to completely remove metal residues on the glass substrate; however, when its content is too high, it will corrode the glass substrate and the generated SiF 6 2- It will adsorb on the metal ion chelate, reduce the charge of the chelate molecules, reduce the electrostatic repulsion, and increase the risk of etching solution precipitation. Preferably, the mass ratio of the first metal ion chelate to the fluoride is A / D≥50.

[0042] Furthermore, based on the total weight of the etching solution composition, the etching solution composition further comprises 0.01% to 0.2% of an etching additive and 0.2% to 2% of an alcohol substance.

[0043] Further, the etching additive is inorganic phosphoric acid and its salt;

[0044] Preferably, the etching additive is at least one of dipotassium hydrogen phosphate, potassium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, disodium hydrogen phosphate, and sodium dihydrogen phosphate; the second metal ion chelating agent such as citric acid, when used in combination with inorganic phosphates, can play a good buffering role, which is beneficial to further improve the stability of etching.

[0045] Etching additives are mainly used to adjust the redox potential between different metal layers. Since the bottom inert metal (molybdenum alloy) is etched slowly, tailing phenomenon is very likely to occur, which affects the later process of display devices. By adding etching additives, the molybdenum alloy layer acts as an anode to speed up its etching rate; but when the content of etching additives is too much, the molybdenum alloy layer is etched too fast, which will cause undercutting phenomenon. Therefore, the content of etching additives in the present invention is controlled within 0.2%.

[0046] The alcohol substance is a diol or triol having 1 to 8 carbon atoms;

[0047] Preferably, the alcohol substance is at least one of ethylene glycol, diethylene glycol, propylene glycol and glycerol.

[0048] Alcohols are mainly used to reduce the decomposition rate of hydrogen peroxide and the surface tension of the etching solution, thereby improving the stability of the system. Monohydric alcohols have little effect on the stability of the etching solution itself; alcohols with large molecular weights (such as polyethylene glycol) easily lead to adsorption residues on the metal layer. Therefore, the present invention prefers dihydric alcohols and trihydric alcohols; at the same time, when the content of dihydric alcohols and trihydric alcohols is less than 0.2%, uneven etching is likely to occur; and when the content exceeds 2%, there is basically no effect on the performance of the etching solution; the present invention limits the content of alcohols to 0.2-2%.

[0049] The etching solution composition of the present invention can achieve good control of H in a high hydrogen peroxide system through the coordination between the first metal ion chelating agent, the second metal ion chelating agent, and the third metal ion chelating agent. 2 O 2 The decomposition rate of the etching liquid is reduced, thereby improving the stability and service life of the etching liquid itself; when it is applied to the etching of metal thin films, the line width loss is small, there is no broken line, no residue, and good compatibility, which greatly improves the etching performance of the etching liquid on the metal layer, and the uniformity and stability of the metal layer etching are better. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0051] Figure 1 This is a SEM image of etching after dissolving 500ppm of Cu in Example 1 of the present invention;

[0052] Figure 2 This is a SEM picture of etching after dissolving 6000ppm of Cu in Example 1 of the present invention. DETAILED DESCRIPTION

[0053] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0054] Examples 1-11 and Comparative Examples 1-3

[0055] The contents of the etching solution components of Examples 1-11 and Comparative Examples 1-3 are shown in Table 1.

[0056] In order to evaluate the etching effect of the etching solution of the present invention, firstly, a sputtering method was used to deposit a thickness of Molybdenum-niobium alloy film and Copper film; then after development and exposure to form a specific anti-corrosion coating pattern; the glass substrate is immersed in the etching solution of each embodiment and comparative example at 30°C for etching, and continuous oscillation. For the convenience of evaluation, the etching time is uniformly set to 30% OE (that is, 30% over-etching time based on the time when the metal film is just etched). After the etching is completed, it is washed with deionized water and blown dry with nitrogen. Finally, the etching results are characterized by means of a scanning electron microscope (SEM). The performance of the etching solution is evaluated by relevant parameters such as the just etching time (EPD), etching cone angle TaperAngle (TA), etching deviation (lateral etching loss CDLoss), etching residue, undercut, precipitate time, sudden boiling time, and etching life (dissolved copper content). The etching results of Examples 1-11 and Comparative Examples 1-3 are shown in Table 2.

[0057] Among them, the just etching time (EPD), in seconds, represents the time when the film layer is just etched clean, which is used to characterize the etching rate;

[0058] Etching cone angle refers to the inclination of the copper bevel. If the cone angle is too large or too small, cracks will occur during the subsequent film evaporation due to poor step coverage, and the subsequent film evaporation becomes difficult. Therefore, it is very important to maintain a suitable cone angle. The required range of the etching cone angle is 30°-70°; the TA fluctuation value of the etching cone angle = the TA value of dissolved Cu 6000ppm - the TA value of dissolved Cu 500ppm;

[0059] When the TA fluctuation value is ≤5°, the stability is considered to be good and is recorded as “√”; when the TA fluctuation value is greater than 5°, the stability is considered to be poor and is recorded as “×”.

[0060] Etching deviation is the difference between the actual size of the pattern formed after etching and the expected size, and the CD loss range is required to be less than 1μm; the fluctuation value of etching deviation CD Loss fluctuation value = CD Loss value of dissolved Cu 6000ppm - CD Loss value of dissolved Cu 500ppm;

[0061] When the CD Loss fluctuation value is ≤0.1um, it is considered that the stability is good and is recorded as "√"; when the CD Loss fluctuation value is greater than 0.1um, it is considered that the stability is poor and is recorded as "×".

[0062] Etching residue refers to the metal element and its oxide particles that remain after the original metal layer is not etched cleanly.

[0063] Table 1 Formula composition in each embodiment and comparative example

[0064]

[0065]

[0066] Table 2 Etching results of various embodiments and comparative examples

[0067]

[0068]

[0069] From the results in Table 1 and Table 2, it can be seen that in Examples 1-3, through the coordination of the three chelating agents, the etching solution of the present invention has a higher etching life at a longer etching time, such as Figure 1-2As shown, after etching by the etching solution of Example 1, there is no etching residue and no undercutting occurs. The TA fluctuation value and the CD Loss fluctuation value are both small, which ensures the uniformity and stability of the etching process. The etching solution used in the present invention reduces the fluctuation range of the characteristic parameters in the entire etching process. Comparing the results of Examples 1 and 4-5, it can be seen that the decomposition rate of hydrogen peroxide is controlled by controlling the content of the first metal ion chelating agent; when the content of the first metal ion chelating agent is too high, the just etching time of the underlying molybdenum alloy is too long, and the etching rate is too low, and the etching requirements cannot be met; when the content of the first metal ion chelating agent is too low, it is impossible to effectively chelate more metal ions, resulting in a short boiling time of hydrogen peroxide. Comparing the results of Example 1 and Examples 6-7, it can be seen that the second metal ion chelating agent begins to play a role in the later stage of the etching process. When the content of the second metal ion chelating agent is too high, the just etching time of the underlying molybdenum alloy is too long; when the content of the second metal ion chelating agent is too low, it is impossible to efficiently chelate copper ions, resulting in accelerated decomposition of hydrogen peroxide, thereby causing large parameter fluctuations. Comparing the results of Example 1 and Examples 8-9, it can be seen that since the third metal chelating agent also has strong acidity, it can well regulate the etching rate of the metal by the liquid; when the content of the third metal ion chelating agent is too high, the pH value of the etching solution is low, the etching cone angle is difficult to control, and a large amount of precipitates appear at the bottom; when the content of the third metal ion chelating agent is too low, the etching is incomplete and there is etching residue. Comparing the results of Example 1 and Examples 10-11, it can be seen that if the F content is too high, the etching rate of molybdenum will be greatly accelerated, and undercutting will occur; at the same time, F will react with the glass substrate to form too much SiF 6 2- When the F content is too low, the molybdenum etching slows down and residues appear. By comparing Example 1 with Comparative Examples 1-3, it can be seen that by controlling the S value, the stability of the etching solution is ensured, so that the TA and CD Loss fluctuation values ​​are stable, and no residues and precipitates are generated.

[0070] The present invention is further described above with the aid of specific embodiments. However, it should be understood that the specific description here should not be construed as limiting the essence and scope of the present invention. Various modifications made to the above embodiments by ordinary technicians in the field after reading this specification are all within the scope of protection of the present invention.

Claims

1. An etching solution composition, characterized in that: The etching solution composition comprises hydrogen peroxide, a first metal ion chelating agent, a second metal ion chelating agent, a third metal ion chelating agent, an inorganic base, an etching inhibitor, a fluoride and water; The first metal ion chelating agent is a compound containing both amino and carboxyl coordination groups in its molecular structure; The second metal ion chelating agent is a compound containing both hydroxyl and carboxyl coordination groups in its molecular structure; The third metal ion chelating agent is a compound containing a sulfonic acid coordination group in its molecular structure; The first metal ion chelating agent, the second metal ion chelating agent, the third metal ion chelating agent, and the fluoride satisfy the following relationship: Wherein, according to the total weight of the etching solution composition: A is the content of the first metal ion chelating agent, in %; a is the number of imino groups, secondary amino groups and carboxyl groups in the first metal ion chelating agent; B is the content of the second metal ion chelating agent, in %; b is the number of hydroxyl groups and carboxyl groups in the second metal ion chelating agent; C is the content of the third metal ion chelating agent, in %; c is the number of sulfonic acid groups in the third metal ion chelating agent; D is the content of the fluoride, in %.

2. The etching solution composition according to claim 1, characterized in that In the first metal ion chelating agent, the second metal ion chelating agent and the third metal ion chelating agent, 2≤a≤10, 2≤b≤6, and 1≤c≤3.

3. The etching solution composition according to claim 1, characterized in that The first metal ion chelating agent, the second metal ion chelating agent, the third metal ion chelating agent, and the fluoride satisfy the following relationship: 200≤S≤1800。 4. The etching solution composition according to claim 1, characterized in that The etching solution composition comprises, by total weight, 10% to 25% of hydrogen peroxide, 1% to 5% of a first metal ion chelating agent, 0.1% to 2% of a second metal ion chelating agent, 0.1% to 1% of a third metal ion chelating agent, 0.1% to 2% of an inorganic base, 0.005% to 0.1% of an etching inhibitor, and 0.01% to 0.10% of a fluoride, with the remainder being water.

5. The etching solution composition according to claim 1, characterized in that: The first metal ion chelating agent is at least one of iminodiacetic acid, nitrilotriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, aminotri(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid) and salts thereof; The second metal ion chelator is at least one of citric acid, malic acid, succinic acid, glycolic acid, tartaric acid and gluconic acid; The third metal ion chelating agent is at least one of hydroxyethyl sulfonic acid, methanesulfonic acid, aminosulfonic acid, phenolsulfonic acid, and methanedisulfonic acid.

6. The etching solution composition according to claim 1, characterized in that The mass ratio of the first metal ion chelating agent to the fluoride is A / D≥50.

7. The etching solution composition according to claim 1, characterized in that: The etching inhibitor is a heterocyclic compound containing one or more nitrogen atoms or sulfur atoms in its molecular structure; Preferably, the etching inhibitor is at least one of 5-aminotetrazolyl, 5-methyltriazole, 1,2,4-triazole, benzotriazole, methylbenzotriazole, carboxybenzotriazole, 2-aminothiazole, cytosine and thymine.

8. The etching solution composition according to claim 1, characterized in that: The inorganic base is at least one of sodium hydroxide and potassium hydroxide; The fluoride is at least one of ammonium bifluoride, hydrofluoric acid, fluoroboric acid, sodium fluoroborate, potassium fluoroborate and ammonium fluoroborate.

9. The etching solution composition according to claim 1, characterized in that: Based on the total weight of the etching solution composition, the etching solution composition further comprises 0.01% to 0.2% of an etching additive and 0.2% to 2% of an alcohol substance.

10. The etching solution composition according to claim 9, characterized in that: The etching additive is inorganic phosphoric acid and its salt; Preferably, the etching additive is at least one of dipotassium hydrogen phosphate, potassium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, disodium hydrogen phosphate, and sodium dihydrogen phosphate; The alcohol substance is a diol or triol having 1 to 8 carbon atoms; Preferably, the alcohol substance is at least one of ethylene glycol, diethylene glycol, propylene glycol and glycerol.

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