Composition and method for removing residues after ashing of semiconductor substrate

Abstract

The invention discloses a composition and method for removing residues after ashing of a semiconductor substrate, and the composition comprises the following components in percentage by weight: 10-60% of a water-soluble organic solvent, 5-30% of an organic alcohol amine compound, 0.1-5% of quaternary amine hydroxide, 0.01-5% of a sugar alcohol compound and 5-40% of water, and does not contain hydroxylamine. The cleaning agent has good cleaning effect and efficiency, the aluminum corrosion rate and the copper corrosion rate are low, sugar alcohol compounds in the formula belong to environment-friendly components, harm to the environment can be remarkably reduced, and the cleaning agent can be used in the new generation semiconductor copper manufacturing process. Meanwhile, the composition provided by the embodiment of the invention also has the capability of cleaning holes with high aspect ratio.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor cleaning, and in particular relates to a composition and a method for removing residues left after ashing of a semiconductor substrate. Background Art

[0002] In the manufacture of semiconductor integrated circuits, photolithography techniques (coating, exposure, development, and etching of a photoresist layer) are required to form fine electronic circuit patterns on a substrate. For example, dry etching, during the patterning process, residues from plasma ashing remain on the surface of the semiconductor substrate. To achieve higher process yields, these etch residues must be removed or cleaned before the next step. This removal or cleaning process is commonly referred to in the industry as "post-etch residue" or "post-ash residue" removal. Because these residues can cause short circuits between wiring lines and adversely affect the electrical performance of semiconductors, thorough removal or cleaning is essential. Incomplete removal or cleaning can lead to reduced electrical performance and reliability of semiconductor devices.

[0003] Wet cleaning is commonly used in the industry to remove or clean post-ashing residues. Numerous cleaning agents or solutions are currently available for semiconductor substrate post-ashing residues, but most contain hydroxylamine. Hydroxylamine derivatives can reduce insoluble functional groups in etching residues to hydrophilic groups during the cleaning process, thus aiding in the removal of etching residues. These agents are widely used in fields such as developing technology and semiconductor cleaning. However, hydroxylamine suffers from low stability and a high explosion risk. This makes hydroxylamine-based cleaning solutions a significant safety hazard. Furthermore, to achieve high cleaning efficiency, conventional cleaning agents may contain a large number of environmentally hazardous chemicals, such as metal corrosion inhibitors, which are detrimental to environmental protection and may pose a threat to human health. Furthermore, while DuPont's commercial cleaning agents, such as EKC-270 and EKC-265, can be used to remove semiconductor substrate post-ashing residues and offer good cleaning performance, they have long cleaning times, typically requiring 20-100 minutes, resulting in low efficiency. This is the basis for the present invention. Summary of the Invention

[0004] In view of at least one of the above-mentioned technical problems, the present invention aims to provide a composition and method for removing residues left after ashing of a semiconductor substrate.

[0005] The technical solution of the present invention is:

[0006] One of the objects of the present invention is to provide a composition for removing residues after ashing of a semiconductor substrate, which comprises, by weight, 10-60% of a water-soluble organic solvent, 5-30% of an organic alcoholamine compound, 0.1-5% of a quaternary ammonium hydroxide, 0.01-5% of a sugar alcohol compound, and 5-40% of water, and does not contain hydroxylamine.

[0007] Preferably, the water-soluble organic solvent includes N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ether alcohol compounds, polyol compounds and mixtures thereof.

[0008] Preferably, the water-soluble organic solvent includes diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol propyl ether, diethylene glycol butyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol propyl ether, dipropylene glycol butyl ether and mixtures thereof.

[0009] Preferably, the organic alcoholamine compound includes N-methylethanolamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, 2-(2-aminoethoxy)ethanol, N-ethylethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, cyclohexylamine diethanol and mixtures thereof.

[0010] Preferably, the quaternary ammonium hydroxide includes tetramethylammonium hydroxide, tetraethylammonium hydroxide and mixtures thereof.

[0011] Preferably, the sugar alcohol compounds include xylitol, sorbitol, maltitol, mannitol and mixtures thereof.

[0012] Preferably, the pH value of the composition is 9-13.

[0013] One of the objects of the present invention is to provide a method for removing residues after ashing of a semiconductor substrate, wherein the surface of the semiconductor substrate where the residues after ashing are to be removed and the photoresist are in contact with any of the above-mentioned compositions.

[0014] Preferably, the temperature of the composition when in contact with the surface of the semiconductor substrate is 50-80°C.

[0015] Compared with the prior art, the advantages of the present invention are:

[0016] The present invention discloses a composition and method for removing residues from semiconductor substrates after ashing. The composition exhibits superior cleaning effectiveness and efficiency, achieving lower rates of aluminum and copper corrosion compared to conventional cleaning agents employing corrosion inhibitors or metal corrosion inhibitors. Furthermore, the sugar alcohol compounds in the formulation are environmentally friendly, significantly reducing environmental hazards, making it suitable for use in next-generation semiconductor copper manufacturing processes. Furthermore, the composition of the present invention also possesses the ability to clean holes with high aspect ratios. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0018] Figure 1 This is an electron microscope photograph of a TiW / Al semiconductor structure before cleaning using the composition for removing residues after ashing of a semiconductor substrate according to Example 2 of the present invention;

[0019] Figure 2 This is an electron microscope photograph of a TiW / Al semiconductor structure after cleaning with the composition for removing residues after ashing of a semiconductor substrate according to Example 2 of the present invention;

[0020] Figure 3 This is an electron microscope photograph of a Si / SiN semiconductor structure before cleaning using the composition for removing residues after ashing of a semiconductor substrate according to Example 2 of the present invention;

[0021] Figure 4 This is an electron microscope photograph of a Si / SiN semiconductor structure after cleaning with the composition for removing residues after ashing of a semiconductor substrate according to Example 2 of the present invention;

[0022] Figure 5 This is an electron microscope photograph of a TSV semiconductor structure before cleaning using the composition for removing residues after ashing of a semiconductor substrate according to Example 2 of the present invention;

[0023] Figure 6 This is an electron microscope photograph of a TSV semiconductor structure after cleaning using the composition for removing residues after ashing of a semiconductor substrate according to Example 2 of the present invention;

[0024] Figure 7 This is an electron microscope photograph of a TSV semiconductor structure after cleaning with the composition for removing residues after ashing of a semiconductor substrate according to Comparative Example 4. DETAILED DESCRIPTION

[0025] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0026] The composition for removing residues from semiconductor substrates after ashing according to an embodiment of the present invention comprises, by weight, 10-60% of a water-soluble organic solvent (preferably 60%), 5-30% of an organic alcohol amine compound (preferably 10%), 0.1-5% of a quaternary ammonium hydroxide (preferably 2.5%), 0.01-5% of a sugar alcohol compound, and 5-40% of water, and does not contain hydroxylamine. The water-soluble organic solvent includes N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ether alcohol compounds, polyol compounds, and mixtures thereof. The specific water-soluble organic solvents mentioned above are all commercially available chemical reagents or are well known to those skilled in the art. It should be noted that when the water-soluble organic solvents are a mixture, the weight of each substance is preferably equal.

[0027] According to some preferred embodiments of the present invention, the water-soluble organic solvent is preferably selected from diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol propyl ether, diethylene glycol butyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol propyl ether, dipropylene glycol butyl ether and mixtures thereof. Further preferred is diethylene glycol butyl ether. The specific water-soluble organic solvents mentioned above are all chemical reagents that can be purchased on the market or are well known to those skilled in the art. It should be noted that when it is a mixture, it is preferred that the weight of each substance is the same.

[0028] According to some preferred embodiments of the present invention, the organic alcoholamine compound is preferably selected from N-methylethanolamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, 2-(2-aminoethoxy)ethanol, N-ethylethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, cyclohexylamine diethanol and mixtures thereof. Triethanolamine is further preferred. The specific organic alcoholamine compounds mentioned above are all chemical reagents that can be purchased on the market or are well known to those skilled in the art. It should be noted that when it is a mixture, it is preferred that the weight of each substance is the same.

[0029] According to some preferred embodiments of the present invention, the quaternary ammonium hydroxide includes tetramethylammonium hydroxide, tetraethylammonium hydroxide, and mixtures thereof. Tetramethylammonium hydroxide is further preferred. The specific quaternary ammonium hydroxides mentioned above are all chemical reagents that can be purchased on the market or are well known to those skilled in the art. It should be noted that when a mixture is formed, the weight of each substance is preferably the same.

[0030] According to some preferred embodiments of the present invention, the sugar alcohol compounds include xylitol, sorbitol, maltitol, mannitol, and mixtures thereof. The specific sugar alcohol compounds mentioned above are all commercially available chemical reagents or are well known to those skilled in the art. It should be noted that, when a mixture is present, the weight of each substance is preferably the same.

[0031] According to some preferred embodiments of the present invention, the composition has a pH value of 9-13.

[0032] The following describes specific embodiments, and uses the metal erosion rate (aluminum erosion rate and copper erosion rate (the materials of the circuits, wires, electrodes, and electroplating materials in the semiconductor of this embodiment contain a large amount of copper) at a temperature of 65°C as the cleaning index of the compositions of Examples 1 to 8 and Comparative Examples 1 to 11, as shown in Tables 1 and 2.

[0033] Table 1: Formulations of the compositions of Examples 1 to 8 and their copper and aluminum corrosion rates at 65°C

[0034]

[0035] Table 2: Formulas of the compositions of Comparative Examples 1 to 11 and their copper and aluminum corrosion rates at 65°C

[0036]

[0037] Comparing Tables 1 and 2, it can be seen that, compared to Examples 1 to 8, the compositions in Comparative Examples 1 and 2 in Table 2 do not contain the sugar alcohol compound, a component also lacking the corrosion inhibitor catechol. The aluminum and copper corrosion rate test results indicate that the compositions in Examples 1 to 4 of the present invention, incorporating the sugar alcohol compound, significantly reduce the aluminum and copper corrosion rates. Comparative Examples 3 and 4 replace the sugar alcohol compound in the present invention's examples with the corrosion inhibitor catechol (catechol, due to its high toxicity, difficulty in degradation, and lack of effective control, poses a clear environmental pollution risk). While the aluminum corrosion rate is reduced compared to Examples 1 to 8, the copper corrosion rate does not significantly improve.

[0038] Furthermore, in order to improve the copper corrosion rate of the composition, a copper corrosion inhibitor such as an azole compound is usually added in the prior art. Since benzotriazole and methylbenzotriazole are commonly used corrosion inhibitors for cleaning semiconductor substrates in the prior art, they can especially protect Cu etching residues from corrosion. Benzotriazole (benzotriazole) has the best performance. Its corrosion protection mechanism is: in the benzotriazole solution, copper replaces the hydrogen atom in the NH functional group of a benzotriazole molecule at the solid-liquid interface, is covalently connected, and is connected to the free electron of the nitrogen atom in another benzotriazole molecule by a coordination bond to form a semi-permeable polymer complex. The two interact to form a precipitation film or an insoluble coordination film, which further polymerizes on the metal surface to form a precipitation protective film, thereby preventing the corrosion process. Therefore, the present invention also adds Comparative Examples 5 to 8. Comparative Examples 5 to 8 are based on Examples 1 or 2 of the present invention, and the addition of corrosion inhibitors (benzotriazole and methylbenzotriazole, which also pose clear environmental risks and are toxic to aquatic organisms. Untreated wastewater from the production process can pollute surrounding water bodies if directly discharged, easily remain in water bodies, and their difficulty in degradation exacerbates ecological risks). Comparative Examples 5 and 6 add benzotriazole, and the contents in the two comparative examples are different. Comparative Examples 7 and 8 add methylbenzotriazole, and the contents in the two comparative examples are different. Similarly, the applicant verified the aluminum corrosion rate and copper corrosion rate of the compositions in each comparative example. It was expected that the aluminum corrosion rate and copper corrosion rate of the compositions of Comparative Examples 5 to 8 would be significantly improved compared to the compositions of Examples 1 or 2 of the present invention. However, a comparison of the results in Table 2 with the results in Table 1 shows that there was no significant improvement in either the aluminum corrosion rate or the copper corrosion rate.

[0039] Furthermore, to enhance the cleaning ability of the composition for high-aspect-ratio holes, a common practice in the prior art is to add a surfactant component such as Triton X-100 (polyethylene glycol octylphenyl ether, environmental hazard identification (N / R51 / 53), a hazardous substance (Xn), toxic to aquatic organisms and difficult to fully degrade, requiring strict industrial emissions control to prevent direct entry into the natural environment). Therefore, the present invention includes Comparative Examples 9 to 11, each of which adds Triton X-100 to Example 1 or Example 2 of the present invention. The content of Triton X-100 in each Comparative Example varies. The compositions of each Comparative Example were also tested for aluminum and copper corrosion rates. It was expected that the aluminum and copper corrosion rates of the compositions of Comparative Examples 9 to 11 would be significantly improved compared to those of Example 1 or 2 of the present invention. However, a comparison of the results in Table 2 with the results in Table 1 shows that neither the aluminum nor the copper corrosion rates were significantly improved.

[0040] Furthermore, the present invention also verifies the effectiveness of the compositions of Examples 1 to 8, the compositions of Comparative Examples 5 to 11, and DuPont's commercial cleaning fluid product EKC-270 (i.e., the time (in minutes) required to clean residues of various materials (for example, aluminum, silicon nitride, and titanium nitride) after plasma ashing at the same temperature (65°C), as shown in Table 3 below).

[0041] Table 3 Comparison of the efficacy of the compositions of Examples 1 to 8 of the present invention, Comparative Examples 5 to 11, and EKC-270

[0042]

[0043] Cleaning residues from plasma ashing on three semiconductor substrates, aluminum, silicon nitride, and titanium nitride, at the same temperature reveals that the cleaning times of the compositions of Examples 1 to 8 of the present invention are shorter than those of the compositions of Comparative Examples 5 to 11 and the EKC-270 cleaning solution, demonstrating that the compositions of the present invention have higher cleaning efficiency. Furthermore, Comparative Examples 5 to 8 show that the addition of the corrosion inhibitors benzotriazole and methylbenzotriazole to Example 1 not only fails to significantly improve the aluminum and copper corrosion rates, but also significantly reduces the cleaning efficiency. The same is true for Comparative Examples 9 to 11; not only do they fail to significantly improve the aluminum and copper corrosion rates compared to Example 1, but their cleaning efficiency also significantly reduces.

[0044] The aluminum and copper erosion rate results in Table 1 indicate that the composition of Example 2 exhibits superior cleaning performance. Therefore, the present invention employed the composition of Example 2 to verify its cleaning performance in various semiconductor structures (TiW / Al, Si / SiN, and TSV), with electron micrographs taken before and after cleaning demonstrating the results.

[0045] in, Figure 1 and Figure 2 This is an electron microscope photograph of residues after dry etching plasma ashing on a TiW / Al semiconductor structure chip when the composition of Example 2 of the present invention is used at a temperature of 65°C. Figure 1 This is an electron microscope photo before cleaning, showing a large amount of dry etching plasma ashing residue ( Figure 1 The red arrow indicates the area). Figure 2 This is an electron microscope photo taken 5 minutes after cleaning, showing that the residue has been completely removed.

[0046] Figure 3 and Figure 4 This is an electron microscope photograph of residues after dry etching plasma ashing on a Si / SiN semiconductor structure chip when the composition of Example 2 of the present invention is used at a temperature of 65° C. Figure 3This is an electron microscope photo before cleaning, showing the dot-shaped residues left after dry etching plasma ashing ( Figure 3 The red arrow indicates the area). Figure 4 This is an electron microscope photo taken 20 minutes after cleaning, showing that the residue has been completely removed.

[0047] Figure 5 and Figure 6 and Figure 7 These are electron microscope photos of residues after dry etching plasma ashing on a TSV semiconductor structure chip when the compositions of Example 2 and Comparative Example 4 of the present invention are used at a temperature of 75° C. Figure 5 This is an electron microscope photo before cleaning. It can be seen that the hole (high aspect ratio of the hole: diameter 65µm, depth 170µm) contains the residue after dry etching plasma ashing ( Figure 5 The red arrow indicates the area). Figure 6 This is an electron microscope photo taken 45 minutes after cleaning. The photo shows that the residue has been completely removed. Figure 7 This is an electron microscope photo of the composition of Comparative Example 4 after cleaning at 75°C for 120 minutes. The results show that there is still residue at the bottom of the hole ( Figure 7 The red circle indicates the area. This indicates that using the corrosion inhibitor catechol instead of xylitol in Example 2 of the present invention does not achieve efficient cleaning results. This demonstrates that the composition of the present invention has good cleaning capabilities for holes with a high aspect ratio (65 µm diameter, 170 µm depth).

[0048] Furthermore, the present invention also verifies the erosion rates of the compositions of Examples 1 to 8 on metals (TEOS, low-K, silicon nitride, titanium nitride, tantalum nitride, thermal oxide), as shown in Table 4.

[0049] Table 4 Metal corrosion rates of the compositions of Examples 1 to 8 of the present invention (unit: Å / min, 25°C)

[0050]

[0051] From the results in Table 4, it can be seen that the compositions of the embodiments of the present invention have excellent compatibility with most dielectric materials.

[0052] In summary, the compositions of the present invention exhibit superior cleaning effectiveness and efficiency. Compared to conventional cleaning agents using corrosion inhibitors or metal corrosion inhibitors, they exhibit lower corrosion rates on both aluminum and copper. Furthermore, the environmentally friendly sugar alcohol compounds in the formulation significantly reduce environmental hazards, making them suitable for use in next-generation semiconductor copper manufacturing processes. Furthermore, the compositions of the present invention also demonstrate the ability to clean holes with high aspect ratios.

[0053] An embodiment of the present invention further provides a method for removing residues from a semiconductor substrate after ashing, specifically comprising: contacting the surface of the semiconductor substrate from which the residues after ashing are to be removed with the composition of any one of the above embodiments.

[0054] Since temperature has a significant impact on the cleaning time of the composition and the metal corrosion rate of the semiconductor substrate, the temperature of the composition is verified accordingly in the examples of the present invention. Taking the composition of Example 2 as an example, the specific results are shown in Table 5 below.

[0055] Table 5 Cleaning time (minutes) and metal corrosion rate of the composition of Example 2 at different temperatures

[0056]

[0057] As shown in Table 5, low temperatures, such as below 50°C, result in poor cleaning of titanium nitride and silicon nitride semiconductor substrates, while cleaning of aluminum semiconductor substrates takes a long time. This demonstrates that temperatures below 50°C are not particularly effective. High temperatures, such as above 80°C, while effective, can lead to excessive metal corrosion, potentially damaging metal circuits. Therefore, the cleaning temperature for the compositions of the present invention is preferably between 50°C and 80°C, with 65°C being a more preferred temperature.

[0058] The sources and specifications of the raw materials in Examples 1 to 8 and Comparative Examples 1 to 11 of the present invention are shown in Table 6 below.

[0059] Table 6 Raw material sources and specifications

[0060]

[0061] The specified directions in this specific embodiment are only for the purpose of facilitating the description of the positional relationship and the coordination relationship between the various components. The above is only a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions under the concept of the present invention fall within the scope of protection of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications without departing from the principle of the present invention should also be considered as the scope of protection of the present invention.

Claims

1. A composition for removing residues from a semiconductor substrate after ashing, characterized in that: The composition comprises, by weight, 10-60% of a water-soluble organic solvent, 5-30% of an organic alcohol amine compound, 0.1-5% of a quaternary ammonium hydroxide, 0.01-5% of a sugar alcohol compound and 5-40% of water, and does not contain hydroxylamine.

2. The composition for removing residues after ashing of a semiconductor substrate according to claim 1, wherein The water-soluble organic solvent includes N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ether alcohol compounds, polyol compounds and mixtures thereof.

3. The composition for removing residues after ashing of a semiconductor substrate according to claim 2, characterized in that: The water-soluble organic solvent includes diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol propyl ether, diethylene glycol butyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol propyl ether, dipropylene glycol butyl ether and a mixture thereof.

4. The composition for removing residues after ashing of a semiconductor substrate according to claim 1, wherein: The organic alcoholamine compounds include N-methylethanolamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, 2-(2-aminoethoxy)ethanol, N-ethylethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, cyclohexylamine diethanol and mixtures thereof.

5. The composition for removing residues after ashing of a semiconductor substrate according to claim 1, characterized in that The quaternary ammonium hydroxide includes tetramethylammonium hydroxide, tetraethylammonium hydroxide and a mixture thereof.

6. The composition for removing residues after ashing of a semiconductor substrate according to claim 1, characterized in that The sugar alcohol compounds include xylitol, sorbitol, maltitol, mannitol and mixtures thereof.

7. The composition for removing residues after ashing of a semiconductor substrate according to claim 1, characterized in that The pH value of the composition is 9-13.

8. A method for removing residues after ashing of a semiconductor substrate, characterized in that: The surface of the semiconductor substrate from which the ashing residue and the photoresist are to be removed is brought into contact with the composition according to any one of claims 1 to 7.

9. The method according to claim 8, characterized in that The temperature of the composition when in contact with the surface of the semiconductor substrate is 50-80°C.

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