Cleaning fluid
By adding metal corrosion inhibitors and chelating agents, especially nitrogen-containing heterocyclic metal corrosion inhibitors, to the cleaning solution, the problems of difficult control of aluminum oxide etching endpoint and material damage are solved, achieving efficient aluminum oxide etching and low-k material protection, which is suitable for semiconductor wafer cleaning.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-09
- Publication Date
- 2026-04-10
AI Technical Summary
In 20nm and even 10nm process nodes, controlling the etching endpoint of aluminum oxide is difficult and can easily lead to damage to metals and low-k materials. Existing cleaning solutions are unable to effectively remove thin aluminum oxide etching termination layers.
Add metal corrosion inhibitors and chelating agents, especially those containing nitrogen heterocycles, to the cleaning solution and adjust the proportions of each component to achieve a high aluminum oxide/aluminum nitride etching rate selectivity ratio, thus protecting low-k materials from damage.
It achieves effective etching of aluminum oxides at 20nm and even 10nm process nodes, while protecting aluminum nitrides and low-k materials from damage. The composition is simple and the raw materials are readily available, making it suitable for semiconductor wafer cleaning.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of semiconductor cleaning solution, in particular to a kind of cleaning solution. BACKGROUND
[0002] One of the applications of aluminum oxide in semiconductors is as an insulator. Due to its high insulating properties and thermal stability, aluminum oxide is widely used in the manufacture of insulating layers of semiconductor devices. In addition, aluminum oxide also has good high-temperature resistance and can maintain its insulating properties in high-temperature environments, so it is widely used in high-temperature semiconductor devices. At the same time, aluminum oxide is also an important substrate material in semiconductors, which can provide good mechanical support and thermal conductivity, allowing the semiconductor to operate stably in high-temperature and high-power environments.
[0003] With the continuous development of Moore's Law, the size of semiconductor structures is becoming smaller and smaller. In 20nm or even 10nm process nodes, one of the key steps in preparing metal via structures is to remove the thin aluminum oxide etch stop layer formed on the surface of the metal and low-k material (low-k dielectric material), while avoiding etching damage to the metal and low-k material. Due to the difficulty in controlling the etch end point of the thin etch stop layer below 20nm process nodes, over-etching often occurs during etching, which damages the contact hole metal and low-k material.
[0004] Therefore, it is a technical problem that needs to be solved by those skilled in the art to provide a cleaning solution for aluminum oxide. SUMMARY
[0005] In order to overcome the above technical defects, the purpose of the present application is to provide a cleaning solution. The cleaning solution of the present application has a high etching rate for aluminum oxide by adding a metal corrosion inhibitor and a chelating agent in the cleaning solution, while having a high aluminum oxide / aluminum nitride etching rate selectivity. When etching the residue containing oxide and ashing on the semiconductor substrate, the aluminum nitride and low-k material present on the substrate are less damaged.
[0006] The present application discloses a cleaning solution, comprising: a solvent, a metal corrosion inhibitor, a chelating agent, an inorganic acid or an organic acid, a buffer system and water.
[0007] Optionally, the metal corrosion inhibitor is a nitrogen-containing heterocyclic metal corrosion inhibitor.
[0008] Optionally, the nitrogen-containing heterocyclic metal corrosion inhibitor includes one or more of benzotriazole, methylbenzotriazole, 1,2,3-triazole, and PY068.
[0009] Optionally, the metal corrosion inhibitor is selected from xylitol, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, lauric acid, cinnamic acid, ammonium acetate, citric acid, ammonium citrate, tartaric acid, ammonium tartrate, allopurinol, melamine, saccharin, guanidine phosphonate, guanidine acetate, glycine, histidine, arginine, tyrosine, serine, glutamic acid, valine, lysine, tryptophan, leucine, cycloserine, L-valine, aspartic acid, polyaspartic acid, L-phenylalanine, β- One or more of the following: alanine, DL-proline, isoleucine, tert-leucine, L-cysteine, L-cysteine, L-tyrosine, glucuronic acid, 1-methylpyrazole, 1-hexyl-3-methylimidazolium bromide, 3-aminobenzoic acid, ε-polylysine, tris(hydroxymethyl)methylglycine, DL-methionine, phenylalanine, 3-amino-3-(p-tolyl)propionic acid, glutamine, N-benzoylglycine, boron nitride, and acetylpyrrole.
[0010] Optionally, the chelating agent is selected from one of iminodiacetic acid, ethylenediaminetetraacetic acid, ethylenediaminetetramethylenephosphonic acid, hexamethylenediaminetetramethylenephosphonic acid, hydroxyethylidene diphosphonic acid, diethyltriaminepentaacetic acid, cyclohexanediaminetetraacetic acid, and (1-hydroxyethylidene) diphosphonic acid.
[0011] Optionally, the chelating agent has a mass percentage content of 0.01% to 2%.
[0012] Optionally, the mass percentage content of the metal corrosion inhibitor is 0.01% to 3%.
[0013] Optionally, the solvent may have a mass percentage content ranging from 1% to 15%.
[0014] Optionally, the organic or inorganic acid has a mass percentage content of 0.1% to 5%.
[0015] Optionally, the mass percentage content of the buffer system is 0.1% to 5%.
[0016] Optionally, the inorganic or organic acid is selected from one or more of oxalic acid, acetic acid, succinic acid, phosphoric acid, hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, tetrafluoroboric acid, hexafluorosilicic acid, monofluorophosphate, and methanesulfonic acid.
[0017] Optionally, the buffer system is selected from one or more of ammonium fluoride, ammonium hydroxide, tetramethylammonium hydroxide, ammonium hexafluorosilicate, and urea.
[0018] Optionally, the solvent is selected from one or more of ethylene glycol, 1,3-propanediol, n-butanol, sorbitol, dipropylene glycol, sulfolane, dipropylene glycol methyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, tripropylene glycol methyl ether, dimethyl sulfoxide, triethanolamine, diethylene glycolamine, N-methylpyrrolidone, N-ethylpyrrolidone, N-hydroxyethylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and N,N-dimethylcyclohexylamine.
[0019] Optionally, at least one component of the inorganic or organic acid or buffer system contains fluorine.
[0020] Compared with existing technologies, the above technical solution has the following advantages:
[0021] 1. By adding metal corrosion inhibitors and chelating agents to the cleaning solution, a high aluminum oxide / aluminum nitride etching rate selectivity ratio is achieved, ensuring the etching rate of aluminum oxide while avoiding damage to aluminum nitride and low-K materials present on the substrate during selective etching of oxides and ashing residues on the semiconductor substrate.
[0022] 2. By using a properly proportioned chelating agent, the etching rate of aluminum oxide is simultaneously improved.
[0023] 3. A nitrogen-containing heterocyclic metal corrosion inhibitor is preferred, which, while ensuring a high etching rate for aluminum oxides, further effectively suppresses the etching rate for aluminum nitrides, thus better protecting the aluminum nitrides.
[0024] 4. By using a reasonable ratio between the components, even if fluorine is added to the system to ensure the etching rate of aluminum oxide, a lower etching rate for non-metals can still be guaranteed.
[0025] 5. Especially in 20nm or even 10nm process nodes, the etching of thin or ultrathin aluminum oxide layers can be carried out while the cleaning process is well controlled, without damaging or significantly damaging the low-k material layer.
[0026] 6. The composition of this cleaning solution is relatively simple, the raw materials are readily available, and the process operation window is large, so it has broad application prospects in the field of semiconductor wafer cleaning. Detailed Implementation
[0027] The advantages of the present invention are further illustrated below through specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.
[0028] The compositions of Examples 1-5 and Comparative Examples 1-5 were prepared according to the cleaning solution components shown in Table 1.
[0029] Table 1. Cleaning solution composition of Examples 1-5 and Comparative Examples 1-5 of the present invention.
[0030]
[0031]
[0032] To investigate the compatibility of the composition with various materials, the etching rates of aluminum oxide, aluminum nitride, and non-metallic materials TEOS, ODC, and BDⅠ were tested. The etching rate testing methods for the five types of wafers are as follows: Blank wafers of aluminum oxide and aluminum nitride were selected, sliced to a size of 5*5cm, and placed under a single-wafer rotary washer for processing. The processing time ranged from 2 to 10 minutes, and the rotation speed was set from 200 to 700 rpm. After processing, the wafers were removed, rinsed with deionized water, and then dried with high-purity nitrogen.
[0033] The etching rate (ER) test method for blank wafers containing aluminum oxide and aluminum nitride is as follows:
[0034] The thickness (D1) of a 5*5cm blank wafer was measured using an ellipsometry (theta-SE).
[0035] The 5*5cm blank metal wafer to be tested was placed in a single-wafer rotary cleaner for processing.
[0036] Take out the 5*5cm blank metal wafer, clean it with deionized water, dry it with high-purity nitrogen, and then use an ellipsometry to measure the thickness (D2) of the blank metal wafer.
[0037] The etching rate can be calculated by substituting the changes in the thickness value and the processing time into the formula, as follows:
[0038] ER=(D1-D2) / T
[0039] Where D1 and D2 are the thicknesses of the blank wafer, with D1 > D2; T is the microcontroller processing time; and the unit of wafer etching rate is...
[0040] The etching rate test method for non-metallic materials (TEOS, ODC, BDI) is as follows:
[0041] The first thickness D1 of the non-metallic material layer (e.g., ODC) on a 5*5cm non-metallic blank wafer was measured using an ellipsometry.
[0042] The 5*5cm non-metallic blank wafer to be tested was placed in a single-wafer rotary cleaner for processing. The time was T and the rotation speed was set to 400 rpm.
[0043] Remove the blank wafer, clean it with deionized water, dry it with high-purity nitrogen, and then use an ellipsometry to measure the second thickness D2.
[0044] The corrosion rate can be calculated by substituting the changes in the thickness value and the processing time into the formula. The calculation formula is as follows:
[0045] ER=(D1-4D2) / T
[0046] D1 and D2 are the first and second thicknesses of the non-metallic blank wafer, respectively; T is the processing time.
[0047] The etching rate testing methods for the five wafers in the following other embodiments and comparative examples all use the same testing methods, which will not be repeated hereafter.
[0048] Table 2 Etching rates of blank wafers in Examples 1-5 and Comparative Examples 1-5
[0049]
[0050] In the table, negative numbers represent wafer etch rate approaching 0. Under laboratory testing conditions, data between -0.5 and 0.5 are all within the error range. Experimental data within this etch rate range indicate that the low-k material in the corresponding embodiment is completely and effectively protected, and the cleaning solution composition under this formulation has no corrosive effect on the non-metallic material.
[0051] As can be seen from Table 2, Examples 1-5 and Comparative Examples 1-3, the addition of several chelating agents can effectively reduce the etching rate of aluminum oxides and aluminum nitrides, resulting in a higher selectivity ratio. Furthermore, compared to the formulation without chelating agents, the cleaning solutions in Examples 1-5 with added chelating agents further reduced the etching rate of non-metals, indicating that the addition of chelating agents causes less damage to non-metals. Therefore, chelating agents are indispensable in this system.
[0052] However, as shown in Comparative Examples 4 and 5, when the mass percentage of the chelating agent exceeds 2%, the etching rate of aluminum oxide cannot meet the requirements, meaning the cleaning solution loses its etching ability against aluminum oxide. Even though the aluminum oxide / aluminum nitride ratio was relatively high in Comparative Example 5, this was because the cleaning rate of aluminum nitride was too low, and the purpose of removing aluminum oxide could not be achieved in this case.
[0053] In summary, because this invention uses a chelating agent added to the cleaning solution composition of aluminum oxide, it effectively reduces the etching rate of aluminum oxide, aluminum nitride, and non-metals, solving the problem that aluminum nitride and non-metals are easily damaged during the cleaning process. More importantly, this invention selects a chelating agent content range of 0.01% to 2% by mass, thus ensuring the etching rate of aluminum oxide at the same time, solving the problem that the etching rate of aluminum oxide cannot be simultaneously controlled.
[0054] Table 3. Cleaning solution composition of Examples 6-10 and Comparative Examples 6-10
[0055]
[0056]
[0057] Table 4. Etching rates of blank wafers in Examples 6-10 and Comparative Examples 6-10
[0058]
[0059] As can be seen from Tables 4 (Examples 6-10 and Comparative Examples 6-10), nitrogen-containing heterocyclic metal corrosion inhibitors, such as benzotriazole, methylbenzotriazole, 1,2,3-triazole, and PY068, can effectively reduce the etching rate of aluminum nitrides and inhibit damage to aluminum nitrides. Simultaneously, they can ensure that the etching rate of aluminum oxides reaches a certain value. In contrast, other metal corrosion inhibitors such as xylitol, cinnamic acid, saccharin, histidine, and leucine increase the etching rate of aluminum nitrides and decrease the aluminum oxide / aluminum nitride etching selectivity ratio.
[0060] Therefore, in the technical solution provided by the present invention, the preferred use of a metal corrosion inhibitor containing nitrogen heterocycles can further improve the etching rate of aluminum nitrides while ensuring a high etching rate of aluminum oxides; further avoid damage to aluminum nitrides and better protect them.
[0061] The results in Table 4 also show that the cleaning fluid exhibits good compatibility with the five materials at different rotation speeds and operating times.
[0062] Table 5. Cleaning solution composition of Examples 11-15 and Comparative Examples 11-15
[0063]
[0064] Table 6. Etching rates of blank wafers in Examples 11-15 and Comparative Examples 11-15
[0065]
[0066]
[0067] As shown in Table 5, the difference between Examples 11-15 and Comparative Examples 11-15 is that the cleaning solution systems in Examples 11-15 all contain fluorine, while those in Comparative Examples 11-15 do not contain fluorine.
[0068] As can be seen from Examples 11-15 and Comparative Examples 11-15 in Table 6, the etching rate of aluminum oxide and aluminum nitride is higher when the system contains fluorine, but when it does not contain fluorine, the purpose of removing aluminum oxide cannot be achieved. At this time, even if the aluminum oxide / aluminum nitride selectivity ratio is large, it is meaningless.
[0069] The cleaning solution provided by this invention, through the rational configuration of the addition ratio of each component, can maintain a very low etching rate for non-metals even in fluorine-containing systems. This solves the problem of unavoidable loss of non-metals in fluorine-containing systems.
[0070] In summary, by adding a suitable ratio of metal corrosion inhibitors and chelating agents to the cleaning solution, a high aluminum oxide / aluminum nitride etching rate selectivity ratio is achieved. This avoids damage to aluminum nitrides and low-k materials present on the substrate during selective etching of oxides and ashing residues on the semiconductor substrate. The cleaning solution of this composition has a relatively simple composition, readily available raw materials, and a wide process operating window, making it a promising candidate for widespread application in the field of semiconductor wafer cleaning.
[0071] In particular, during specific selective etching, especially at 20nm or even 10nm process nodes, the aluminum oxide cleaning solution provided by this invention does not damage or significantly damage the low-k material layer while etching thin or ultra-thin aluminum oxide layers. This solves the problem of the difficulty in controlling the cleaning of thin or ultra-thin aluminum oxide layers and achieves unexpected technical results.
[0072] It should be noted that the embodiments of the present invention have better implementability and are not intended to limit the present invention in any way. Any person skilled in the art may use the above-disclosed technical content to change or modify it into equivalent effective embodiments. However, any modifications or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.
Claims
1. A cleaning solution, characterized in that, include: Solvents, metal corrosion inhibitors, chelating agents, inorganic or organic acids, buffer systems, and water.
2. The cleaning solution as described in claim 1, characterized in that, The metal corrosion inhibitor is a nitrogen-containing heterocyclic metal corrosion inhibitor.
3. The cleaning solution as described in claim 2, characterized in that, The nitrogen-containing heterocyclic metal corrosion inhibitors include one or more of benzotriazole, methylbenzotriazole, 1,2,3-triazole, and PY068.
4. The cleaning solution as described in claim 1, characterized in that, The metal corrosion inhibitor is selected from xylitol, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, lauric acid, cinnamic acid, ammonium acetate, citric acid, ammonium citrate, tartaric acid, ammonium tartrate, allopurinol, melamine, saccharin, guanidine phosphonate, guanidine acetate, glycine, histidine, arginine, tyrosine, serine, glutamic acid, valine, lysine, tryptophan, leucine, cycloserine, L-valine, aspartic acid, polyaspartic acid, L-phenylalanine, and β-alanine. One or more of the following: acid, DL-proline, isoleucine, tert-leucine, L-cysteine, L-cysteine, L-tyrosine, glucuronic acid, 1-methylpyrazole, 1-hexyl-3-methylimidazolium bromide, 3-aminobenzoic acid, ε-polylysine, tris(hydroxymethyl)methylglycine, DL-methionine, phenylalanine, 3-amino-3-(p-tolyl)propionic acid, glutamine, N-benzoylglycine, boron nitride, and acetylpyrrole.
5. The cleaning solution as described in claim 1, characterized in that, The chelating agent is selected from one of iminodiacetic acid, ethylenediaminetetraacetic acid, ethylenediaminetetramethylenephosphonic acid, hexamethylenediaminetetramethylenephosphonic acid, hydroxyethylidene diphosphonic acid, diethyltriaminepentaacetic acid, cyclohexanediaminetetraacetic acid, and (1-hydroxyethylidene) diphosphonic acid.
6. The cleaning solution as described in claim 1, characterized in that, The chelating agent has a mass percentage content of 0.01% to 2%.
7. The cleaning solution as described in claim 1, characterized in that, The mass percentage content of the metal corrosion inhibitor is 0.01% to 3%.
8. The cleaning solution as described in claim 1, characterized in that, The solvent has a mass percentage content ranging from 1% to 15%.
9. The cleaning solution as described in claim 1, characterized in that, The organic or inorganic acid has a mass percentage content of 0.1% to 5%.
10. The cleaning solution as described in claim 1, characterized in that, The buffer system has a mass percentage content of 0.1% to 5%.
11. The cleaning solution as described in claim 1, characterized in that, The inorganic or organic acid is selected from one or more of oxalic acid, acetic acid, succinic acid, phosphoric acid, hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, tetrafluoroboric acid, hexafluorosilicic acid, monofluorophosphate, and methanesulfonic acid.
12. The cleaning solution as described in claim 1, characterized in that, The buffer system is selected from one or more of ammonium fluoride, ammonium hydroxide, tetramethylammonium hydroxide, ammonium hexafluorosilicate, and urea.
13. The cleaning solution as described in claim 1, characterized in that, The solvent is selected from one or more of ethylene glycol, 1,3-propanediol, n-butanol, sorbitol, dipropylene glycol, sulfolane, dipropylene glycol methyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, tripropylene glycol methyl ether, dimethyl sulfoxide, triethanolamine, diethylene glycolamine, N-methylpyrrolidone, N-ethylpyrrolidone, N-hydroxyethylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and N,N-dimethylcyclohexylamine.
14. The cleaning solution according to any one of claims 1-13, characterized in that, At least one component of an inorganic or organic acid or a buffer system contains fluorine.