Copper interconnection process cleaning solution for protecting low-k material and preparation method and application thereof

Abstract

The invention relates to a copper interconnection process cleaning solution for protecting a low-k material and a preparation method and application of the copper interconnection process cleaning solution for protecting the low-k material, and the copper interconnection process cleaning solution for protecting the low-k material comprises the following components in parts by weight: 10-30 parts of a composite functional agent; 1-10 parts of a stabilizer; 1-10 parts of a corrosion inhibitor; 0.1 to 1 part of a surfactant; and 40-80 parts of a solvent. The compound functional agent is adopted, the aromatic amino acid derivative and the organic sulfonium salt derivative are combined, the compound functional agent is compounded to form a net-shaped supramolecular structure, and the cleaning agent has good material compatibility to metal and non-metal materials while efficient cleaning is achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of semiconductor manufacturing process, and particularly relates to a cleaning solution for protecting low-k material in copper interconnection process, and a preparation method and application thereof. BACKGROUND

[0002] With the further improvement of chip integration, the copper interconnection structure is increasingly fine and complex, which brings greater challenges to the subsequent cleaning process. After the dry etching (such as plasma etching) or chemical mechanical polishing (CMP) of the copper process, various pollutants will be generated on the wafer surface, which directly affects the final quality and performance of the chip. Therefore, the development of copper interconnection technology is closely related to efficient and reliable cleaning technology, and the progress of cleaning technology has become one of the key supports for promoting the application of copper interconnection technology in more advanced processes.

[0003] Copper interconnection technology has become a mature and core technology in the field of integrated circuit manufacturing, and the industry is generally committed to solving the problem of removing the residues on the wafer surface after the copper process to meet the increasing requirements of chip performance and yield.

[0004] The current development trend presents the following characteristics: first, the demand for multifunctional cleaning solution is increasing, and traditional single-function cleaning solution has been difficult to adapt to complex pollution conditions; second, material compatibility has become a focus, with the widespread use of low dielectric constant (low-k) materials and other new materials in chips, the cleaning solution needs to effectively remove pollutants while minimizing damage to these sensitive materials; third, the concept of green environmental protection is gradually integrated into the development of cleaning technology, and the development of environmentally friendly cleaning solution has become an industry consensus.

[0005] For cleaning the residues on the wafer surface after the copper process, the existing technology mainly falls into two categories: the first category is acid cleaning solution technology, which usually uses dilute hydrochloric acid, sulfuric acid or nitric acid as the main component. By utilizing the chemical properties of inorganic acids to react with copper oxides, copper oxides are dissolved, thereby achieving the removal of copper oxide pollutants, but the corrosion rate of copper is high and the compatibility is poor.

[0006] The second category is complexing agent cleaning solution technology, CN101597548A discloses a cleaning solution for plasma etching residues, which forms a stable complex with metal ions through complexing agents, thereby gently removing metal residues. Compared with acid cleaning solution, the corrosion of metal is relatively small. In addition, in order to improve the removal ability of organic residues (such as photoresist), some cleaning solutions also add surfactants or oxidizing agents to enhance the cleaning effect.

[0007] As can be seen from the above, although existing copper residue cleaning technologies can solve the problem of wafer surface contamination to a certain extent, they still have many obvious shortcomings and are difficult to meet the needs of current advanced copper interconnect processes.

[0008] This invention addresses the shortcomings of existing cleaning solutions, such as significant damage to low-k materials, reduced dielectric properties, and consequently device performance degradation. The core innovation lies in the introduction of aromatic amino acid derivatives and organic sulfonate derivatives, which are then combined through electrostatic / hydrogen bonding to form a composite functional agent. This significantly improves cleaning efficiency, enabling the simultaneous removal of copper oxides, etching byproducts, and organic residues. It overcomes the limitations of existing technologies that require single-function, step-by-step cleaning, greatly shortening process time and increasing production efficiency. Furthermore, this composite functional agent exhibits excellent material protection properties. While efficiently cleaning residues, it effectively prevents corrosion of copper wires and low-k materials, ensuring the structural integrity and performance stability of the device and enhancing material compatibility. Summary of the Invention

[0009] The technical problem solved by this invention is that existing cleaning solutions cause significant damage to low-k dielectric materials, which reduces dielectric properties and leads to device performance degradation.

[0010] In view of the technical problems existing in the prior art, the present invention designs a cleaning solution for protecting low-k materials in copper interconnect process, as well as a preparation method and application. The cleaning solution can still maintain extremely good cleaning efficiency even under the condition of pure immersion process without ultrasonic cleaning.

[0011] It should be noted that, in this invention, unless otherwise specified, the specific meaning of "comprising" in relation to composition definition and description includes both open-ended meanings such as "comprising," "including," etc., and closed-ended meanings such as "composed of," etc., and similar meanings.

[0012] To solve the aforementioned technical problems, the present invention adopts the following solution:

[0013] [The first technical solution]

[0014] A cleaning solution for protecting low-k materials in copper interconnect processes, characterized in that it comprises the following components by weight:

[0015] 10-30 parts of compound functional agent;

[0016] Stabilizer 1-10 parts;

[0017] 1-10 parts corrosion inhibitor;

[0018] Surfactant 0.1-1 part;

[0019] Solvent 40-80 parts;

[0020] The composite functional agent is a mixture of aromatic amino acid derivatives and organic sulfonium salt derivatives.

[0021] Furthermore, the aromatic amino acid derivative is one or more of Nα-(2,4-dinitro-5-fluorophenyl)-D-leucine ammonium, Nα-(2,4-dinitro-5-fluorophenyl)-L-propanamide, N-(2,4-dinitrophenyl)-L-alanine, and L-leucine p-nitroaniline.

[0022] Furthermore, the organosulfonium salt derivative is tri-p-tolylsulfonium hexafluorophosphate and / or triphenylsulfonium hexafluorophosphate.

[0023] Furthermore, the mass ratio of the aromatic amino acid derivative to the organic sulfonium salt derivative is 1:1-10.

[0024] Furthermore, the stabilizer is a polycarboxylic acid.

[0025] Furthermore, the stabilizer is one or more of ethylenediaminetetraacetic acid, 1,2-cyclohexanediaminetetraacetic acid, iminodiacetic acid, diethylenetriaminepentaacetic acid, glycine, and citric acid.

[0026] Furthermore, the corrosion inhibitor is an azole.

[0027] Furthermore, in this invention, any azole corrosion inhibitor can be used to provide a certain corrosion inhibition effect.

[0028] Furthermore, the corrosion inhibitor is one or more of benzotriazole, 1,2,4-triazole, 1,2,3-triazole, 5-carboxybenzotriazole, tetrazolium, and 5-methyltetrazolium.

[0029] Furthermore, the surfactant is one or more of lauric acid, dodecylbenzenesulfonic acid, dodecyl sulfuric acid, and perfluorooctanoic acid.

[0030] Furthermore, in this invention, the choice of solvent is not limited, but is based on the ability to dissolve each component in the cleaning solution.

[0031] Furthermore, the solvent is one or more of acetone, ethanol, methanol, dimethylformamide, dimethyl sulfoxide, acetonitrile, dichloromethane, diethyl ether, and deionized water.

[0032] In this invention, in order to further optimize the performance of the cleaning fluid, the components can be optimized as follows: 15-25 parts of composite functional agent; 3-7 parts of stabilizer; 2-6 parts of corrosion inhibitor; 0.3-0.6 parts of surfactant; and 50-80 parts of solvent.

[0033] In this invention, the aromatic amino acid derivative is preferably Nα-(2,4-dinitro-5-fluorophenyl)-D-leucine ammonium.

[0034] In this invention, the organosulfonate derivative is preferably tri-p-tolylsulfonate hexafluorophosphate.

[0035] In this invention, the mass ratio of the aromatic amino acid derivative to the organic sulfonate derivative is preferably 1:1-5.

[0036] In this invention, the stabilizer is preferably iminodiacetic acid.

[0037] In this invention, the corrosion inhibitor is preferably 5-methyltetrazole.

[0038] In this invention, the surfactant is preferably perfluorooctanoic acid (PFOA).

[0039] In this invention, the composite functional agent in the cleaning solution for protecting low-k materials in copper interconnect processes plays a unique role:

[0040] Firstly, this composite functional agent has the advantages of rapid cleaning and strong material compatibility, exhibiting excellent cleaning performance and quickly removing etching residues. Furthermore, the composite functional agent can be compounded to form a network supramolecular structure, resulting in a synergistic enhancement effect.

[0041] Secondly, the cationic moiety of tri-p-tolylsulfonium hexafluorophosphate: sulfonium center (S + The compound consists of three p-tolyl groups, possessing a positive charge and a hydrophobic aromatic ring; the aromatic ring moiety of Nα-(2,4-dinitro-5-fluorophenyl)-D-leucine ammonium: the 2,4-dinitro-5-fluorophenyl group exhibits strong electron-withdrawing properties and may participate in π-π stacking or charge transfer interactions; the amide moiety: the amino and carbonyl groups of D-leucine ammonium can provide hydrogen bond donor / acceptor sites. The combination of these two groups results in: 1) the positive charge of the sulfonium ion (S... + 1) It can undergo cation-π interactions with the electron-rich aromatic ring in D-leucine ammonium to form local dimers or chain structures; 2) Leucine ammonium's -NH 3+ (Protonated ammonium) can react with PF6 - Fluorine atoms or nitro oxygen atoms form hydrogen bonds (N—H···F / O), and the N—H or C=O of the amide group (—CONH—) can form C—H···O / N hydrogen bonds with the methyl or aromatic ring C—H of the p-tolyl group. These hydrogen bonds connect the units into layered or one-dimensional chains. PF6 -Fill the gaps and stabilize the charge;

[0042] Third, hydrophobic interactions and π-π stacking further link layers / chains, forming a porous or network supramolecular structure. This network supramolecular structure removes residues through the following mechanisms: 1) Acid + nucleophilic bifunctional cleaning: H+ generated by sulfonium salts... + 1) Softening / fracture residues: Nitroaryl derivatives are further chemically modified to make them soluble. 2) Prevention of redeposition: The chelating effect of D-leucine ammonium stabilizes metal ions, preventing their re-adsorption onto the wafer surface. 3) Selective cleaning: The introduction of fluorine atoms enhances the removal of fluoropolymer residues (such as CF32-C4 ... x Affinity to etching byproducts.

[0043] [Second Technical Solution]

[0044] A method for preparing the above-mentioned cleaning solution for protecting low-k materials in copper interconnect processes includes the following steps:

[0045] Step 1: Weigh out the respective amounts of each component;

[0046] Step 2: Add all components to a container and stir the mixture at room temperature until a clear and transparent solution is formed, which is the copper interconnect process cleaning solution for protecting low-k materials.

[0047] [The third technical solution]

[0048] A method for using the aforementioned cleaning solution for protecting low-k materials in copper interconnect processes includes the following steps:

[0049] Step 1: Prepare the copper interconnect process cleaning solution into an aqueous solution with a mass percentage concentration of 20-100% using ultrapure water. Then, use this aqueous solution to immerse the semiconductor chip at 30-50°C for 10-40 minutes to obtain the immersed semiconductor chip.

[0050] Step 2: Rinse the soaked semiconductor chip twice in ultrapure water and blow off the surface moisture with nitrogen gas to complete the cleaning process of the semiconductor chip.

[0051] Furthermore, the soaking temperature in step 1 of the method is preferably 30-40℃.

[0052] Furthermore, the soaking time in step 1 of the method is preferably 10-20 minutes.

[0053] [Fourth technical solution]

[0054] The use of the aforementioned copper interconnect process cleaning solution for protecting low-k materials in cleaning semiconductor chips.

[0055] Furthermore, the copper interconnect process cleaning solution that protects low-k materials is particularly useful for cleaning residues left after Cu process etching.

[0056] This invention provides a cleaning solution for protecting low-k materials in copper interconnect processes, its preparation method, and its application, which have the following beneficial effects:

[0057] 1. This invention employs a composite functional agent that combines aromatic amino acid derivatives with organic sulfonium salt derivatives. This composite functional agent, when combined, forms a network supramolecular structure with a synergistic enhancement effect. This network supramolecular structure removes residues through the following mechanisms: 1) Acid + nucleophilic dual-function cleaning: H+ generated by the sulfonium salt... + 1) Softening / fracture residues: Nitroaryl derivatives are further chemically modified to make them soluble. 2) Prevention of redeposition: The chelating effect of D-leucine ammonium stabilizes metal ions, preventing their re-adsorption onto the wafer surface. 3) Selective cleaning: The introduction of fluorine atoms enhances the removal of fluoropolymer residues (such as CF32-C4 ... x Affinity to etching byproducts.

[0058] 2. The cleaning solution of the present invention has good material compatibility with both metal and non-metal materials while cleaning with high efficiency.

[0059] 3. After cleaning, the chip does not need to be rinsed with acetone; it can be rinsed with pure water only, which is harmless to the environment and human body.

[0060] 4. The cleaning solution of the present invention does not corrode the chip, the cleaning process has no special requirements, and no ultrasonic treatment is required to completely wash away the residues adhering to the chip. Subsequent rinsing with pure water is sufficient, and there is no dirt residue after rinsing.

[0061] Therefore, the cleaning solution of the present invention has very good application prospects and potential for large-scale industrial promotion in the field of semiconductor chip cleaning. Attached Figure Description

[0062] Figure 1 This is a scanning electron microscope image of the etched chip before cleaning, magnified 50,000 times.

[0063] Figure 2 : A scanning electron microscope image magnified 50,000 times after the etched chip was cleaned with the cleaning solution prepared in Example 1;

[0064] Figure 3 : A scanning electron microscope image of the etched chip after cleaning with the cleaning solution prepared in Comparative Example 1, magnified 50,000 times. Detailed Implementation

[0065] The present invention will be further described below with reference to specific embodiments and accompanying drawings:

[0066] In this invention, Examples 1-8 and Comparative Examples 1-4 disclose a variety of cleaning solutions, the components and mass ratios of which are shown in Tables 1 and 2.

[0067] Table 1. Components and proportions of cleaning solutions in Examples 1-8

[0068] Table 2. Components and proportions of cleaning solutions in Comparative Examples 1-4

[0069] The preparation method of the copper interconnect process cleaning solution for protecting low-k materials according to the present invention is as follows:

[0070] Step 1: Weigh out the respective amounts of each component;

[0071] Step 2: Add all components to a container and stir the mixture at room temperature until a clear and transparent solution is formed, which is the copper interconnect process cleaning solution for protecting low-k materials.

[0072] The method of using the copper interconnect process cleaning solution for protecting low-k materials according to this invention is as follows:

[0073] Step 1: Prepare the copper interconnect process cleaning solution into an aqueous solution with a mass percentage concentration of 20-100% using ultrapure water. Then, use this aqueous solution to immerse the semiconductor chip at 30-50°C for 10-40 minutes to obtain the immersed semiconductor chip.

[0074] Step 2: Rinse the soaked semiconductor chip twice in ultrapure water and blow off the surface moisture with nitrogen gas to complete the cleaning process of the semiconductor chip.

[0075] Regarding performance testing and explanation:

[0076] Performance 1 Cleaning Effect Test Method:

[0077] The chip was cleaned using the cleaning solutions from the above embodiments and comparative examples of the present invention. The cleaning method includes the following steps:

[0078] Step 1: Immerse the chip in the semiconductor chip cleaning solution at 40°C until the residue is completely removed, record the cleaning time, and obtain the cleaned chip;

[0079] Step 2: Rinse the soaked chip twice in ultrapure water and blow dry the surface moisture with nitrogen gas to complete the chip cleaning process.

[0080] Step 3: Take a picture of the cleaned chip using a scanning electron microscope (SEM).

[0081] The ultrapure water used in step 2 is deionized water with a resistance of at least 18 MΩ.

[0082] Performance 2 Cu corrosion rate test method:

[0083] Step 1: Cut the Cu sheet into 3*3cm pieces 2 The sample was tested using a four-point probe resistance meter to measure the pre-corrosion value A1, in units of... ;

[0084] Step 2: Immerse the chip in the semiconductor chip cleaning solution of the present invention at 40°C for 30 minutes;

[0085] Step 3: Rinse the sample treated in Step 2 twice in ultrapure water, dry it with N2, and use a four-point probe resistance meter to measure the value A2 after corrosion. The unit is... ;

[0086] Step 4: Corrosion rate calculation formula ER = (A1 - A2) / t; where ER is in units of t. / min, where t is the sample processing time in minutes.

[0087] Performance 3 TEOS corrosion rate test method:

[0088] Step 1: Cut the TEOS sample into 3*3cm pieces 2 The sample was tested using a non-metallic film thickness gauge to determine the pre-corrosion value A1, in units of... ;

[0089] Step 2: Immerse the chip in the semiconductor chip cleaning solution of the present invention at 40°C for 30 minutes;

[0090] Step 3: Rinse the sample processed in Step 2 twice in ultrapure water, dry it with N2, and measure the post-etching value A2 using a non-metallic film thickness gauge. (Unit: ...) ;

[0091] Step 4: Corrosion rate calculation formula ER = (A1 - A2) / t; where ER is in units of t. / min, where t is the sample processing time in minutes.

[0092] The performance test results of the cleaning solutions obtained in Examples 1-8 and Comparative Examples 1-4 are shown in Table 3.

[0093] Table 3 Test Data

[0094] Analysis and explanation of the test results:

[0095] As can be seen from the test data in Table 3, the cleaning solution of this invention uses a composite functional agent, which combines aromatic amino acid derivatives with organic sulfonate derivatives to form a network supramolecular structure, resulting in a synergistic enhancement effect. While achieving high-efficiency cleaning, it also exhibits good material compatibility with both metals and non-metals. In contrast, Comparative Example 1 does not contain aromatic amino acid derivatives and is unable to form a network supramolecular structure. This not only leads to a significant decrease in cleaning speed and an inability to effectively soften and chemically modify etching residues, but also results in severe residue redeposition due to the inability of metal ions to be stabilized and re-adsorbed onto the wafer surface. Furthermore, it exhibits poor compatibility with copper and TEOS.

[0096] Comparative Example 2 lacks an organic sulfonium salt derivative, resulting in the loss of the positively charged sulfonium center (S). + The presence of hydrophobic aromatic rings prevents the formation of a network supramolecular structure, resulting in a lack of synergistic enhancement during the cleaning process. Furthermore, the absence of hydrophobic interactions from the hydrophobic aromatic rings further weakens the ability to encapsulate and separate residues, leading to incomplete wafer cleaning and increased corrosion rates of copper and TEOS.

[0097] Comparative Example 3 used hexafluorophosphate. Due to the different substituent groups attached to the sulfonium center, the original structural compatibility was disrupted, making it impossible to form a stable porous or network structure. This resulted in a slower cleaning speed, reduced ability to encapsulate residues, and increased corrosion rates on copper and TEOS. Comparative Example 4 used tetrabutyltrifluoromethanesulfonate. Lacking an electron-rich aromatic ring structure, it could not form cation-π interactions with the sulfonium center (S+) of the organic sulfonium salt. It also lacked hydrogen bond donor / acceptor sites such as amino and carbonyl groups, preventing it from participating in the construction of supramolecular structures through hydrogen bonds. Furthermore, it lacked groups for chelating metal ions, leading to the inability to remove residues quickly. Additionally, the structural characteristics of tetrabutyltrifluoromethanesulfonate may cause compatibility issues with low-k materials or copper interconnect layers, potentially damaging the substrate material.

[0098] Further comparison can be made using the accompanying diagrams in the instruction manual:

[0099] Figure 1 This is a scanning electron microscope image of the etched chip before cleaning, magnified 50,000 times. Figure 2 The image is a scanning electron microscope image magnified 50,000 times after the etched chip was cleaned with the cleaning solution prepared in Example 1. Figure 3 This is a scanning electron microscope image of the etched chip after cleaning with the cleaning solution prepared in Comparative Example 1, magnified 50,000 times.

[0100] from Figures 1-2 It can be seen that the cleaning solution of Example 1 can completely remove residues after soaking at 40°C for 10 minutes. Figure 3Using the cleaning solution from Comparative Example 1, the sample was soaked at 40°C for 20 minutes. Some residues were observed in the figure, indicating that the lack of aromatic amino acid derivatives made it difficult to form a network supramolecular structure, resulting in a significant reduction in cleaning selectivity and overall cleaning performance.

[0101] The present invention has been described above by way of example with reference to the embodiments and accompanying drawings. Obviously, the implementation of the present invention is not limited to the above-described manner. Any improvements made by adopting the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A cleaning solution for protecting low-k materials in copper interconnect processes, characterized in that, Based on parts by weight, it includes the following components: 10-30 parts of compound functional agent; Stabilizer 1-10 parts; 1-10 parts corrosion inhibitor; Surfactant 0.1-1 part; Solvent 40-80 parts; The composite functional agent is a mixture of aromatic amino acid derivatives and organic sulfonium salt derivatives.

2. The copper interconnect process cleaning solution for protecting low-k materials according to claim 1, characterized in that: The aromatic amino acid derivative is one or more of Nα-(2,4-dinitro-5-fluorophenyl)-D-leucine ammonium, Nα-(2,4-dinitro-5-fluorophenyl)-L-propanamide, N-(2,4-dinitrophenyl)-L-alanine, and L-leucine p-nitroaniline.

3. The copper interconnect process cleaning solution for protecting low-k materials according to claim 1, characterized in that: The organosulfonium salt derivative is tri-p-tolylsulfonium hexafluorophosphate and / or triphenylsulfonium hexafluorophosphate.

4. The copper interconnect process cleaning solution for protecting low-k materials according to claim 1, characterized in that: The mass ratio of the aromatic amino acid derivative to the organic sulfonium salt derivative is 1:1-10.

5. The copper interconnect process cleaning solution for protecting low-k materials according to claim 1, characterized in that: The stabilizer is a polycarboxylic acid.

6. The copper interconnect process cleaning solution for protecting low-k materials according to claim 1, characterized in that: The corrosion inhibitor is an azole.

7. The copper interconnect process cleaning solution for protecting low-k materials according to claim 1, characterized in that: The surfactant is one or more of lauric acid, dodecylbenzenesulfonic acid, dodecyl sulfuric acid, and perfluorooctanoic acid.

8. A method for preparing a copper interconnect process cleaning solution for protecting low-k materials as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Weigh out the respective amounts of each component; Step 2: Add all components to a container and stir the mixture at room temperature until a clear and transparent solution is formed, which is the copper interconnect process cleaning solution for protecting low-k materials.

9. A method of using the copper interconnect process cleaning solution for protecting low-k materials as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Prepare the copper interconnect process cleaning solution into an aqueous solution with a mass percentage concentration of 20-100% using ultrapure water. Then, use this aqueous solution to immerse the semiconductor chip at 30-50°C for 10-40 minutes to obtain the immersed semiconductor chip. Step 2: Rinse the soaked semiconductor chip twice in ultrapure water and blow off the surface moisture with nitrogen gas to complete the cleaning process of the semiconductor chip.

10. The use of a copper interconnect process cleaning solution for protecting low-k materials as described in any one of claims 1-7 in cleaning semiconductor chips.

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