Composition and method for removing residues after ashing of semiconductor substrate

Abstract

The present invention discloses a composition and method for removing residues after ashing of semiconductor substrates. The composition comprises, by weight, 0.05-10 wt% of an organic amine compound, 0.001-10 wt% of a wetting agent, and 80-99.5 wt% of water, wherein the wetting agent comprises at least one of a polyol compound and a surfactant. The composition is hydroxylamine-free and fluoride-free, and is primarily composed of an organic amine compound, a wetting agent (a polyol compound and / or a surfactant), and water to form a water-based cleaning agent. The composition does not contain a large amount of organic solvents, chelating agents, or silicate corrosion inhibitors, resulting in lower costs and environmental friendliness. The composition operates at low temperatures, preventing the loss of water and active ingredients in the cleaning agent. The composition exhibits good stability, a low metal erosion rate, and stable cleaning performance. The composition effectively removes residues after dry etching plasma ashing, while exhibiting minimal or no erosion of metal circuits, dielectric layers, and substrate materials on the original wafer.

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 (coating, exposure, development, and etching of a photoresist layer) is required to form fine electronic circuit patterns on a substrate. During the patterning process, residues may remain on the surface of the semiconductor substrate. After the patterning process, these etch residues must be removed or cleaned before proceeding to the next step. This removal or cleaning process is commonly referred to in the industry as "post-etch residue" or "post-ash residue" removal. These residues can cause short circuits between wirings or poor adhesion during subsequent metal or dielectric layer deposition processes, adversely affecting the electrical performance of the semiconductor. Therefore, these residues must be thoroughly removed or cleaned. Incomplete removal or cleaning can lead to reduced electrical performance and reliability of the semiconductor device.

[0003] Wet cleaning is commonly used in the industry to remove or clean ashing residues. Existing traditional cleaning agents mainly include hydroxylamine, fluorine, semi-aqueous amine (without hydroxylamine) and water-based cleaning agents.

[0004] Hydroxylamine cleaning fluids offer excellent cleaning effectiveness. Because hydroxylamine and its salts are important chemical raw materials, they are widely used in fields such as semiconductor cleaning. However, hydroxylamine is relatively unstable and prone to explosion at high operating temperatures. This poses significant safety risks during the preparation and use of hydroxylamine cleaning fluids.

[0005] Fluorine-based cleaning agents generally include fluoride + amine compounds + organic solvents + water. Fluorine-based cleaning agents can be used for cleaning at relatively low temperatures (room temperature to 50°C), but they still have some disadvantages. For example, they cannot effectively control the corrosion of the base material. Fluoride, such as ammonium fluoride or hydrofluoric acid, is extremely harmful to the human body in an acidic environment. Direct contact is toxic and can cause bone erosion without immediate treatment. Long-term inhalation can also cause osteoporosis in the human body, posing a great safety risk.

[0006] Semi-aqueous amine cleaners are mainly composed of organic amines and organic stripping solvents, water and metal corrosion inhibitors. However, these cleaners usually operate at high temperatures (50-90°C), and are less effective in removing inorganic metal residues, so they are not widely used.

[0007] Water-based cleaning solutions primarily consist of a metal-ion-free base, a silicate corrosion inhibitor, a metal oxoate, a chelating agent, and water. They operate at low temperatures and are environmentally friendly. However, existing water-based cleaning agents also have drawbacks. For example, silicate corrosion inhibitors increase the viscosity of the cleaning solution, making it difficult to clean fine lines or tiny holes on chip structures. Chemical bonding caused by silicate corrosion inhibitors during the cleaning process can cause discoloration and contamination of some substrates. Furthermore, as the pH value decreases, they hydrolyze to produce particulates that can contaminate the wafer. This is the basis for the present invention. Summary of the Invention

[0008] In response to at least one of the above-mentioned technical problems, the present invention aims to provide a composition and method for removing residues after ashing of semiconductor substrates. The composition does not contain fluoride or hydroxylamine, can effectively remove residues after dry etching plasma ashing at a relatively low temperature (below 50°C), and has no or very low corrosion to the metal circuits, dielectric layers, and wafer substrate materials on the original wafer.

[0009] The technical solution of the present invention is:

[0010] 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 percentage, 0.05-10 wt% of an organic amine compound, 0.001-10 wt% of a wetting agent, and 80-99.5 wt% of water, wherein the wetting agent comprises at least one of a polyol compound or a surfactant.

[0011] Preferably, the organic amine compound includes at least one of 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 quaternary ammonium hydroxide.

[0012] Preferably, the quaternary ammonium hydroxide includes at least one of tetramethylammonium hydroxide and tetraethylammonium hydroxide.

[0013] Preferably, the polyol compound includes at least one of ethylene glycol, propylene glycol, glycerol, polyethylene glycol, and polypropylene glycol.

[0014] Preferably, 0.1-10 wt% of a phenolic corrosion inhibitor is also included.

[0015] Preferably, the phenolic corrosion inhibitor includes at least one of tert-butylcatechol, catechol, resorcinol, 2,3-dihydroxybenzoic acid, and gallic acid.

[0016] Preferably, it has a pH value of 10-12.

[0017] Preferably, the operating temperature thereof is 10 to 50°C.

[0018] One of the objects of the present invention is to provide a method for removing residues from a semiconductor substrate after ashing, wherein the surface of the semiconductor substrate from which the residues are to be removed is contacted with any of the above-mentioned compositions.

[0019] Preferably, the temperature of the composition when in contact with the surface of the semiconductor substrate is 10-50°C.

[0020] Compared with the prior art, the advantages of the present invention are:

[0021] The composition and method for removing residues after ashing of semiconductor substrates of the present invention do not contain hydroxylamine, which can solve the safety hazard problem caused by the explosion of hydroxylamine; do not contain fluoride, which can solve the safety risk problem of fluoride. The water-based cleaning agent is composed of organic amine compounds as the main body, combined with a wetting agent (polyol compound and / or surfactant) and water. It does not contain a large amount of organic solvents, nor does it contain chelating agents and silicate corrosion inhibitors, and is lower in cost and environmentally friendly. Operating at low temperature (10 to 50°C), the water and effective ingredients in the cleaning agent are not easily lost, the composition has good stability, a low metal corrosion rate, stable cleaning performance, and can effectively remove residues after dry etching plasma ashing, without corroding or causing very low corrosion to the metal circuits, dielectric layers and wafer substrate materials on the original wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0023] Figure 1 Schematic diagram of the aluminum corrosion rate of the composition for removing residues after ashing of a semiconductor substrate according to Example 1 of the present invention at different temperatures;

[0024] Figure 2 This is an electron microscope photograph of an SRO / TEOS / SiN semiconductor structure before cleaning using the composition for removing residues after ashing of a semiconductor substrate according to Example 11 of the present invention;

[0025] Figure 3 This is an electron microscope photograph of a SRO / TEOS / SiN semiconductor structure after cleaning with the composition for removing residues after ashing of a semiconductor substrate according to Example 11 of the present invention;

[0026] Figure 4 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 11 of the present invention;

[0027] Figure 5This 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 11 of the present invention. DETAILED DESCRIPTION

[0028] 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.

[0029] A composition for removing residue from semiconductor substrates after ashing according to an embodiment of the present invention comprises, by weight percentage, 0.05-10 wt% of an organic amine compound, 0.001-10 wt% of a wetting agent, and 80-99.5 wt% of water, wherein the wetting agent comprises at least one of a polyol compound or a surfactant and does not contain hydroxylamine, fluoride, a large amount of organic solvent, an organic carboxylic acid chelating agent, or a silicate corrosion inhibitor. The aforementioned components and reagents are all commercially available or well-known chemical reagents to those skilled in the art.

[0030] According to some preferred embodiments of the present invention, the organic amine compound preferably includes at least one of N-methylethanolamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, 2-(2-aminoethoxy)ethanol, N-ethylethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, cyclohexylaminediethanol, and quaternary ammonium hydroxide. The specific organic amine compounds mentioned above are all chemical reagents that can be purchased on the market or are well known to those skilled in the art. Further preferably, the quaternary ammonium hydroxide includes at least one of tetramethylammonium hydroxide and tetraethylammonium hydroxide.

[0031] According to some preferred embodiments of the present invention, the polyol compound includes at least one of ethylene glycol, propylene glycol, glycerol, polyethylene glycol, and polypropylene glycol. The specific polyol compounds mentioned above are all chemical reagents that can be purchased on the market or are well known to those skilled in the art. Surfactants are compounds that contain both hydrophilic and lipophilic groups in molecules such as common soaps and shampoos on the market. For example, the surfactant Triton X-100 (polyethylene glycol octylphenyl ether) is used in some embodiments of the present invention. When the wetting agent is a compound of a polyol compound and a surfactant, the specific ratio of the two is not particularly limited and can be selected as 1:1.

[0032] According to some preferred embodiments of the present invention, the composition can also be compounded with a phenolic corrosion inhibitor instead of the silicate corrosion inhibitor of the prior art. The addition of a phenolic corrosion inhibitor can further improve the protectiveness of aluminum and copper materials, that is, further reduce the corrosion of aluminum and copper materials. Preferably, the content of the phenolic corrosion inhibitor in the formula is 0.1-10wt% by weight. The embodiments of the present invention optimize and control the content of the phenolic corrosion inhibitor, while improving the protectiveness without significantly affecting the pH value of the formula. Exemplarily, the phenolic corrosion inhibitor of the embodiments of the present invention is selected from at least one of tert-butylcatechol, catechol, resorcinol, 2,3-dihydroxybenzoic acid, and gallic acid. The specific phenolic corrosion inhibitors mentioned above are all chemical reagents that can be purchased on the market or are well known to those skilled in the art.

[0033] According to some preferred embodiments of the present invention, the composition has a pH value of 10-12. Because the formula is primarily composed of organic amine compounds, the composition is alkaline. By optimizing the formula and controlling the amounts of wetting agent and water, the pH value of the formula is maintained at 10-12. Compared to existing acidic cleaning agents, the composition exhibits less corrosion to aluminum, copper, and other conductive wires. Furthermore, by controlling the pH value, the composition exhibits no or minimal corrosion to the metal wiring, dielectric layers, and substrate materials already on the wafer.

[0034] According to some preferred embodiments of the present invention, the composition operates at a temperature of 10 to 50°C. Because the compositions of the present invention are water-based cleaning agents, which contain a significant proportion of water, operating at low temperatures can reduce the loss of water and effective ingredients in the cleaning agent, thereby improving the stability of the composition and achieving extremely high cleaning efficiency. Compared to existing cleaning agents such as DuPont EKC-270, which require an operating temperature of 60-80°C, the compositions of the present invention operate at a more moderate temperature and consume less energy.

[0035] The applicant has discovered that the compositions of the present invention are fast and highly effective (30-300 seconds) when used to remove residues after ashing of semiconductor substrates. While not suitable for operation on traditional slot-type machines, where the time required to pull all the chip racks apart can lead to variations between individual chips, they are highly suitable for single-wafer cleaning machines used in next-generation processes. These machines can precisely control process times, allowing the compositions of the present invention to maximize their effectiveness, significantly improving production efficiency and reducing both cycle time and costs.

[0036] The advantages and rationality of the composition of the present invention are explained below with reference to specific examples, as shown in Tables 1 to 4.

[0037] Table 1: Formulations of the compositions of Examples 1 to 20 and their aluminum corrosion rates at an operating temperature of 25°C

[0038]

[0039]

[0040] Note: “-” in the table means not contained or not added. The average molecular weight of polyethylene glycol-200 is 200 g / mol.

[0041] Table 1 shows examples of compositions using the present invention. The aluminum erosion rate test results for Examples 1 to 7 in Table 1 show that, when used to clean semiconductor substrates, compositions containing only monoethanolamine exhibit significantly lower aluminum erosion rates than compositions containing only tetramethylammonium hydroxide (Examples 1 and 5). In compositions using a mixture of monoethanolamine and tetramethylammonium hydroxide as the organic amine compound (Examples 2 to 4, and Examples 6 and 7), when the amount of monoethanolamine is higher than that of tetramethylammonium hydroxide, the aluminum erosion rate is significantly lower. Furthermore, as the ratio of monoethanolamine to tetramethylammonium hydroxide increases, the erosion rate decreases. After reaching a certain ratio (in Example 7, the ratio is 5:1, which is lower than that of Example 1, while in Example 6, the ratio is 2:1, which is higher than that of Example 1), it is lower than that of the composition containing only monoethanolamine. Thus, the applicant has determined, through optimization, that an organic amine compound dosage of 0.05-10 wt% can ensure extremely high cleaning efficiency while also ensuring low costs.

[0042] Examples 8 to 13 are compared with Example 6. Specifically, different types of polyol compounds are added to Example 6 (Examples 8 to 11 each add a polyol compound, Example 12 adds a surfactant, and Example 13 adds both a polyol compound and a surfactant). The aluminum erosion rate test results show that the aluminum erosion rate of the composition with the addition of the polyol compound is lower than that of the examples without the addition of the polyol compound (i.e., Examples 1 to 7). Moreover, the aluminum erosion rate of the composition with the addition of the polyol compound and the surfactant is greatly reduced compared to the addition of the polyol compound alone, indicating that the addition of a wetting agent can reduce the aluminum erosion rate and the combination of the polyol compound and the surfactant can further reduce the aluminum erosion rate.

[0043] As can be seen from Examples 14 to 16, as the amount of polyol compound increases, the aluminum erosion rate gradually decreases, but the magnitude of the decrease is relatively small. Therefore, the applicant has optimized the wetting agent dosage to 0.001-10 wt % to ensure extremely high cleaning efficiency while also reducing costs.

[0044] As can be seen from Examples 17 to 20, different phenolic corrosion inhibitors were added to the composition of Example 11. The aluminum corrosion rate test results show that the addition of the phenolic corrosion inhibitor further slowed the aluminum corrosion rate without affecting the cleaning effect. Thus, the applicants have optimized the optimal phenolic corrosion inhibitor dosage to 0.1-10 wt %, ensuring extremely high cleaning efficiency at a low cost.

[0045] Table 2 Cleaning time for the compositions of Examples 1 to 20 to remove residues from various materials after plasma ashing (temperature 25°C, unit: seconds)

[0046] aluminum Silicon nitride Titanium nitride Example 1 30 120 180 Example 2 15 60 90 Example 3 <15 60 90 Example 4 <15 30 60 Example 5 <15 30 60 Example 6 15 90 120 Example 7 30 120 180 Example 8 45 180 240 Example 9 30 120 180 Example 10 60 240 300 Example 11 45 180 240 Example 12 180 360 >600 Example 13 180 300 >600 Example 14 45 180 240 Example 15 60 210 300 Example 16 90 240 360 Example 17 60 180 240 Example 18 90 240 300 Example 19 60 180 240 Example 20 90 240 300

[0047] As shown in Table 2, the composition of the embodiment of the present invention can be used to remove residues after plasma ashing of various semiconductor materials in a cleaning time of less than 600 seconds. In particular, the time for aluminum is even shorter, less than 60 seconds. The time is very short and the reaction speed is fast.

[0048] Table 3 Corrosion rate of the compositions of Examples 8 to 13 on different metals (Units) 25℃)

[0049]

[0050] To verify the reliability of the compositions of the present invention, as shown in Table 3, the applicant also tested the erosion rates of the compositions of Examples 8 to 13 on various metals. As shown in Table 3, the compositions of Examples 8 to 13 exhibited minimal erosion on metals such as aluminum, copper, silicon oxide films made from electronic-grade tetraethyl orthosilicate (TEOS), low-K insulating materials, silicon nitride, titanium nitride, and thermal oxide films made at high temperatures. This demonstrates that the compositions of the present invention can be used to clean and remove residues after ashing of semiconductor substrates.

[0051] Furthermore, in order to further verify the optimal operating temperature of the composition of the embodiment of the present invention for removing the residue after plasma ashing of the semiconductor substrate, the applicant selected Example 11 as the formula of the optimized composition and used it to remove the residue after ashing of the semiconductor substrate. In order to verify the optimal process parameters of the composition of Example 11 for removing the residue after ashing of the semiconductor substrate, the applicant conducted the following experiment: Figure 1 Verification of the aluminum corrosion rate using the composition of Example 5 at different temperatures shown. Figure 1 It can be seen that the applicant found that the aluminum corrosion rate of the composition of Example 11 was small (lower than ), however, at temperatures exceeding 50°C, such as 60°C, the aluminum erosion rate significantly increases. Furthermore, the aluminum erosion rate remains excellent at 10°C, below room temperature. Therefore, the applicant has verified that the operating temperature for the compositions of the present invention to remove residues is between 10°C and 50°C. If the operating temperature is too low, resulting in residues remaining during the removal process, it is recommended that the operating temperature be controlled at no more than 50°C.

[0052] Conventional organic amine compound cleaning agents generally contain multifunctional organic acids (such as phthalic acid, oxalic acid, and ethylenediaminetetraacetic acid-disodium (EDTA-2Na)) as chelating agents to chelate the metals in the aqueous solution of the composition, so as to chelate the metal ions precipitated / dissolved on the chip after the semiconductor cleaning. In theory, after adding multifunctional organic acids to the formulation of the composition of the embodiment of the present invention, the stability and cleaning efficiency of the composition will all increase. However, the applicant found that, as shown in Table 4 below, after adding a certain amount of multifunctional organic acid to the formulation of the composition of the present invention, the aluminum corrosion rate not only did not decrease, but increased. Therefore, the formulation of the present application does not contain multifunctional organic acids, which not only reduces costs but also has better cleaning efficiency. In other words, the composition of Example 11 of the present invention has a lower aluminum corrosion rate and better protection for the aluminum circuits on the cleaned chip.

[0053] Table 4 Formula of the composition of Example 11 of the present invention and Comparative Examples 1 to 3

[0054]

[0055] Note: “-” in the table means not contained or not added. The average molecular weight of polyethylene glycol-200 is 200 g / mol.

[0056] After cleaning a high-load wafer volume of 25 12-inch wafers per liter, the composition of Example 11 of the present invention can still achieve the cleaning effect of removing plasma ashing residues on the wafer and a lower aluminum erosion rate. At the same time, the aluminum etching rate can also be controlled within This result demonstrates that, even without the addition of a multifunctional organic acid, the composition of Example 11 maintains excellent solution stability, achieving the desired wafer cleaning results while also achieving a lower aluminum erosion rate. In summary, the composition of the present invention provides superior protection for aluminum circuits on cleaned wafers.

[0057] The present invention also provides a method for removing residue from a semiconductor substrate after ashing, wherein the surface of the semiconductor substrate from which the residue is to be removed is contacted with the composition of Examples 1 to 20. To achieve optimal removal, the temperature of the composition when in contact with the semiconductor substrate surface is 10 to 50°C.

[0058] Figures 2 to 5 Different semiconductor structures are also given (where Figure 2 and Figure 3 It is a SRO / TEOS / SiN semiconductor structure. Figure 4 and Figure 5 (a TiW / Al semiconductor structure) was cleaned at 25°C using the composition of Example 11 to remove the residue after ashing ( Figure 2 and Figure 4 Before removal, Figure 3 for peace Figure 5 After removal, Figure 3 The cleaning time is 180 seconds. Figure 5 Electron microscope photo of the cleaning time (45 seconds). Figure 2 and Figure 3 It is clear from comparison that Figure 2 The wafer before processing is covered with dot-shaped residues from dry etching plasma ashing. Figure 3 The residue on the wafer has been removed. Figure 4 The display chip is covered with residues from dry etching plasma ashing. Figure 5 The residue on the wafer has been removed.

[0059] The sources and specifications of the raw materials in Examples 1 to 20 and Comparative Examples 1 to 3 of the present invention are as follows in Table 5:

[0060] Table 5 Sources and specifications of raw materials

[0061]

[0062] 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 invention relates to a novel surfactant comprising 0.05-10 wt % of an organic amine compound, 0.001-10 wt % of a wetting agent and 80-99.5 wt % of water, wherein the organic amine compound is at least one of monoethanolamine and tetramethylammonium hydroxide, the wetting agent comprises at least one of a polyol compound or a surfactant, the polyol compound comprises at least one of ethylene glycol, propylene glycol, glycerol and polyethylene glycol, and the surfactant is Triton X-100.

2. The composition according to claim 1, characterized in that The organic amine compound also includes at least one of N-methylethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, 2-(2-aminoethoxy)ethanol, N-ethylethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, cyclohexylamine diethanol, and tetraethylammonium hydroxide.

3. The composition according to any one of claims 1 to 2, characterized in that Also included is 0.1-10 wt% of a phenolic corrosion inhibitor.

4. The composition according to claim 3, characterized in that The phenolic corrosion inhibitor includes at least one of tert-butylcatechol, catechol, resorcinol, 2,3-dihydroxybenzoic acid, and gallic acid.

5. The composition according to claim 1, characterized in that It has a pH value of 10-12.

6. The composition according to claim 1, characterized in that Its operating temperature is 10 to 50°C.

7. 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 is to be removed is brought into contact with the composition according to any one of claims 1 to 6.

8. The method according to claim 7, characterized in that The temperature of the composition when in contact with the surface of the semiconductor substrate is 10-50°C.

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