A cleaning agent for semiconductor chip after polishing and its preparation method and application

Abstract

The application relates to a semiconductor chip polishing post-cleaning agent and a preparation method and application thereof, wherein the semiconductor chip polishing post-cleaning agent comprises the following components according to weight parts: 1-10 parts of an additive, 1-10 parts of a chelating agent, 1-5 parts of an organic regulator, 30-40 parts of a solubilizer and 30-40 parts of ultrapure water. The additive and the chelating agent are used in cooperation, when a polar group in a molecule of the additive approaches a benzene ring in the chelating agent, a large pi bond is formed due to conjugation, the adsorption capacity of the chelating agent is enhanced, and the corrosion inhibition performance is improved.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor manufacturing processes, and particularly relates to a cleaning agent for semiconductor chip polishing, its preparation method, and its application. Background Technology

[0002] As the semiconductor industry evolves towards higher integration, smaller process sizes, and lower power consumption, copper, with its superior conductivity (resistivity of only 1.7 μΩ·cm, far lower than the 2.7 μΩ·cm of traditional aluminum interconnects) and resistance to electromigration, has replaced aluminum as the core material for metal interconnects in advanced processes at 7nm and below. Chemical mechanical polishing (CMP) technology has been effectively applied to the double damascene process for multilayer copper wiring. This process primarily achieves high material removal rate (MRR) and low surface defects on the copper surface through a combination of chemical erosion in the polishing slurry and mechanical abrasion.

[0003] Because the polishing slurry contains a large number of nanoparticles, corrosion inhibitors, and other chemicals, and the fresh copper surface after polishing has high activity, it readily adsorbs a large amount of contaminants. Organic contaminants are particularly problematic; benzotriazole (BTA), a corrosion inhibitor, is an example. It adheres to the copper surface hydrophobically, leading to severe drying and poor adhesion to multilayer stacks, significantly impacting integrated circuit performance. Therefore, effective post-CMP cleaning techniques are essential.

[0004] Currently, commonly used CMP post-cleaning methods can generally be divided into two categories: wet cleaning and dry cleaning. Wet cleaning technology has a wide range of applications, numerous usage schemes, and good selectivity for impurities and substrates, capable of reducing various impurities and contaminants to very low levels. By the early 1980s, CMP post-cleaning technology had developed to its fifth generation. Excessive contaminants on the polished surface are one of the main reasons for the decline in yield, and the cleaning of high-precision surfaces has become one of the key issues restricting the improvement of CMP technology.

[0005] Early cleaning agents were acidic, but damage defects in metal interconnect materials and low dielectric constant interlayer damage are unavoidable problems with acidic cleaning agents. Therefore, current research focuses on the design and development of alkaline cleaning agents. Tetramethylammonium hydroxide (TMAH) has high water solubility and thermal stability, making it one of the most widely used components in alkaline chemical mechanical polishing (CMP) post-cleaning agents. Electrochemical experiments have also demonstrated that TMAH-based cleaning agents have high removal efficiency for BTA residues on copper surfaces. However, TMAH is highly alkaline, corrosive to copper, and difficult to degrade, which greatly limits its further application in CMP post-cleaning. Cu-BTA cleaning agents must have a pH less than 3 or greater than 10, but acidic cleaning agents may cause equipment corrosion. Most importantly, acidic cleaning agents must be used directly and are unstable. In alkaline cleaning agents, high-pH chemicals dissolve only CuO on the surface, leaving Cu2O, thus passivating the surface, while low-pH chemicals dissolve both CuO and Cu2O. Therefore, increasing research focuses on the removal of Cu-BTA by alkaline cleaning agents.

[0006] Traditional amino-based alkaline cleaning agents, such as ammonium hydroxide, are effective at removing BTA, but ammonium hydroxide has a high corrosion rate on Cu. A non-hydroxylamine alkaline cleaning agent composed of potassium hydroxide, cesium hydroxide, ethylene glycol, glycerol, and iminodiacetic acid can effectively remove BTA; however, the mass fractions of potassium hydroxide and cesium hydroxide used are too high, and the excessive alkalinity of the cleaning agent can easily cause corrosion on the Cu surface.

[0007] Therefore, to address the problem of severe corrosion of Cu by existing alkaline cleaning agents, this invention innovatively utilizes hydrogen bonds formed between additives and chelating agents to create an adsorption film on the Cu surface, thereby inhibiting Cu corrosion. Simultaneously, through the synergistic effect between the additives and chelating agents, the content of copper ions in the solution is reduced, thus reducing the formation of Cu-BTA. Summary of the Invention

[0008] The technical problem solved by this invention is the severe corrosion of Cu by existing alkaline cleaning agents.

[0009] In view of the technical problems existing in the prior art, the present invention designs a cleaning agent for semiconductor chip polishing, its preparation method and application, which can effectively clean residual BTA and its complexes, and has almost no corrosion to Cu.

[0010] 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.

[0011] To solve the aforementioned technical problems, the present invention adopts the following solution:

[0012] [The first technical solution]

[0013] A cleaning agent for semiconductor chips after polishing, characterized in that it comprises the following components by weight:

[0014] 1-10 parts of additives;

[0015] Chelating agent 1-10 parts;

[0016] 1-5 parts organic regulator;

[0017] 30-40 parts of solubilizer;

[0018] 30-40 parts ultrapure water;

[0019] The additive is an amine substance that contains both hydrophilic and hydrophobic groups.

[0020] Further, the additive is one or more of 1-oleoyl-2-(12-biotin(aminododecanoyl))-sn-glycerol-3-phosphate ethanolamine, 1-(1Z-octadecenyl)-2-oleoyl-sn-glycerol-3-phosphate ethanolamine, and 1-palmitoyl-2-oleoylphosphatidylethanolamine.

[0021] Furthermore, the chelating agent is a compound containing both hydroxyl and carboxyl groups.

[0022] Further, the chelating agent is one or more of Ganglioside GM3 (CAS: 124579-05-1), (2R,3R,4R,5R)-5-acetamido-2,-dihydroxy-6-oxo-4-(((2R,3R,4S,5R,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran (CAS: 161619-43-8), 8-hydroxyquinoline glucoside, and 4-carboxy-6-hydroxy-2,2'-bipyrimidine.

[0023] Furthermore, the organic regulator is an amine compound.

[0024] Further, the organic regulator is one or more of 2-(1,3-benzothiazol-2-yl)acetamide, p-hydroxyphenylacetamide, and 2-hydroxybenzo-1-carbonthioamide.

[0025] Furthermore, the solubilizer is a strongly polar aprotic solvent.

[0026] Furthermore, the solubilizer is one or more of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and hexamethylphosphoric triamine.

[0027] In this invention, in order to further optimize the performance of the cleaning agent after semiconductor chip polishing, the components can be optimized as follows: 3-8 parts of additives, most preferably 3-5 parts; 3-10 parts of chelating agent, most preferably 3-5 parts; 1-3 parts of organic regulator; 30-36 parts of solubilizer; and 30-36 parts of ultrapure water.

[0028] In this invention, the additive is preferably 1-oleoyl-2-(12-biotin(aminododecanoyl))-sn-glycerol-3-phosphate ethanolamine.

[0029] In this invention, the chelating agent is preferably Ganglioside GM3.

[0030] In this invention, the organic regulator is preferably 2-(1,3-benzothiazol-2-yl)acetamide.

[0031] In this invention, the solubilizer is preferably dimethyl sulfoxide.

[0032] In this invention, the additives in the cleaning agent after semiconductor chip polishing play a unique role:

[0033] This additive possesses both polar hydrophilic and nonpolar hydrophobic groups. The polar hydrophilic groups dissociate in solution, existing as negatively charged particles that form passivates with Cu ions. These passivates adhere to the Cu surface, inhibiting Cu oxidation and reducing the surface CuO content. Under the influence of electrostatics and the hydrophobic groups, the additive is adsorbed onto the CuO surface via physical adsorption, inhibiting subsequent CuO reactions to some extent. Through the synergistic effect of chemical and physical action, the additive reduces the corrosion rate of Cu.

[0034] In this invention, the chelating agent in the cleaning agent after semiconductor chip polishing plays a unique role:

[0035] Firstly, the polar groups of the chelating agent can be rapidly adsorbed onto the Cu surface, altering the characteristics of the electrical double layer on the metal surface, increasing the activation energy during the corrosion process, and thus inhibiting corrosion.

[0036] Secondly, the presence of carboxyl and hydroxyl functional groups in the chelating agent molecule enables it to form soluble chelates with copper ions. This stronger chelating ability disrupts the chemical adsorption equilibrium between BTA and the Cu surface, leading to the breakage of the Cu-BTA covalent bond. Unsaturated copper ions then provide new adsorption sites for the chelating agent molecules in solution, forming stable and soluble chelates. This process continuously removes the Cu-BTA adsorption film from the Cu surface.

[0037] Thirdly, the synergistic effect of additives and chelating agents: when the polar groups in the additive molecules approach the benzene ring in the chelating agent, a large π bond is formed due to the conjugation effect, which enhances the adsorption capacity of the chelating agent and thus improves the corrosion inhibition performance.

[0038] In this invention, the organic modifier in the cleaning agent after semiconductor chip polishing plays a unique role:

[0039] Organic regulators can provide an alkaline environment, under which BTA in cleaning agents containing organic regulators will be used as BTA. - In this form, CuO, generated by oxidation on the Cu surface, dissolves to form Cu(OH)2, while Cu2O remains on the Cu surface. The positively charged Cu2O readily attracts BTA. - An adsorption film is formed through a chemical reaction. Under alkaline conditions, the Cu-BTA ionization equilibrium is disrupted, and Cu... + Easily oxidized to Cu 2+ Organic regulators and Cu 2+ The reaction forms a complex, leading to the destruction of the Cu-BTA structure. Cu-BTA is removed through a synergistic effect of chemical and mechanical action.

[0040] [Second Technical Solution]

[0041] A method for preparing the above-mentioned cleaning agent for polishing semiconductor chips includes the following steps:

[0042] Step 1: Weigh out the respective amounts of each component;

[0043] Step 2: Add all components except ultrapure water to the container and stir at room temperature until all materials are completely dissolved. Finally, add ultrapure water and mix well to obtain the cleaning agent after semiconductor chip polishing.

[0044] [The third technical solution]

[0045] A method for using the above-mentioned cleaning agent after semiconductor chip polishing includes the following steps:

[0046] Step 1: Dilute the cleaning agent for polishing semiconductor chips with ultrapure water 50-100 times, then immerse the chip at room temperature for 60-90 seconds to obtain the chip after immersion.

[0047] Step 2: Rinse the soaked chip in ultrapure water at least twice to complete the cleaning process of the semiconductor chip. After cleaning, dry it with N2.

[0048] [Fourth technical solution]

[0049] The use of the above-mentioned post-polishing cleaning agent for semiconductor chips in the field of cleaning semiconductor chips.

[0050] This invention provides a cleaning agent for semiconductor chip polishing, its preparation method, and its application, which have the following beneficial effects:

[0051] 1. The additives, chelating agents, and organic regulators in this cleaning agent all contain hydroxyl groups in their structures. Substances with similar structures are more likely to dissolve in each other, increasing the solubility of each component in the system.

[0052] 2. Both additives and chelating agents can be adsorbed onto the Cu surface, and the intermolecular attraction further reduces the intermolecular distance. The additives and chelating agents promote each other synergistically through hydrogen bonding networks and coordination interactions, increasing the density of the adsorbed film on the Cu surface, enhancing corrosion inhibition, and suppressing corrosion.

[0053] 3. The phosphonic acid or amide groups in the additives of this cleaning agent can respectively connect with the carboxyl groups in the chelating agent to form a capsule-like structure, which has a strong chelating ability for copper ions. At the same time, there is a strong hydrogen bonding interaction between the additives and the chelating agent, which enhances the chelating ability for copper ions. The two work synergistically to reduce the content of copper ions in the solution, thereby reducing the formation of Cu-BTA.

[0054] Therefore, the cleaning agent 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

[0055] Figure 1 : Scanning electron microscope image of the copper sheet surface before cleaning, magnified 20,000 times.

[0056] Figure 2 : This is a scanning electron microscope image magnified 20,000 times after cleaning with the cleaning agent of Example 1.

[0057] Figure 3 : This is a scanning electron microscope image magnified 20,000 times after cleaning with the cleaning agent used in Comparative Example 1. Detailed Implementation

[0058] The present invention will be further described below with reference to specific embodiments and accompanying drawings:

[0059] In this invention, Examples 1-6 and Comparative Examples 1-5 disclose a variety of cleaning agents, the components and their mass ratios of which are shown in Tables 1 and 2.

[0060] Table 1. Components and proportions of cleaning agents used after polishing semiconductor chips in Examples 1-6

[0061] Table 2. Components and proportions of cleaning agents in Comparative Examples 1-5

[0062] The preparation method of the cleaning agent for semiconductor chip polishing according to the present invention is as follows:

[0063] Step 1: Weigh out the respective amounts of each component;

[0064] Step 2: Add all components except ultrapure water to the container and stir at room temperature (25°C) until all materials are completely dissolved. Finally, add ultrapure water and mix well to obtain the cleaning agent after semiconductor chip polishing.

[0065] The method of using the cleaning agent after polishing the semiconductor chip according to this invention is as follows:

[0066] Step 1: Dilute the cleaning agent after polishing the semiconductor chip with ultrapure water 50-100 times, then immerse the chip at room temperature (25℃) for 60-90 seconds to obtain the chip after immersion.

[0067] Step 2: Rinse the soaked chip in ultrapure water at least twice to complete the cleaning process of the semiconductor chip. After cleaning, dry it with N2.

[0068] Regarding performance testing and explanation:

[0069] The test method for performance 1 cleaning effect is as follows:

[0070] The copper sheet after the cleaning process was tested using an electron microscope at 20,000x magnification. The test results are shown below. Figure 1-3 .

[0071] The test method for performance 2 metal corrosion is as follows:

[0072] The corrosion rate of copper in different cleaning agents was tested using an electrochemical method. The specific test method was as follows: copper (3 mm in diameter) was used as the electrochemical working electrode, platinum as the counter electrode, and a saturated Ag / AgCl electrode as the reference electrode. The cleaning agents used in the examples and comparative examples were used as electrolyte solutions. The open-circuit potential-time (OCP-t) curves and dynamic potential polarization curves (Tafel) of the working electrode were measured to obtain the corrosion current and voltage. The corrosion rate of copper was calculated using the following formula:

[0073] V=6×10 9 ×[(M×I corr ) / (n×F×ρ)]

[0074] V: Corrosion rate, in Å / min;

[0075] M: Molar mass, in g / mol;

[0076] Icorr Self-corrosion current, unit: A / cm 2 ;

[0077] n: Number of charges in the electrochemical reaction;

[0078] F: Faraday constant;

[0079] ρ: Density, unit g / cm³ 3 .

[0080] The performance test results of the cleaning agents obtained in Examples 1-6 and Comparative Examples 1-5 are shown in Table 3.

[0081] Table 3 Test Data

[0082] Analysis and explanation of the test results:

[0083] As can be seen from the test data in Table 3, there is no residue after cleaning with the cleaning agent of the present invention, and the corrosion rate is less than 1 Å / min, which is significantly lower than the corrosion rate of comparative examples 1-5.

[0084] Because Comparative Example 1 lacked additives and Comparative Example 2 lacked chelating agents, the density of the adsorption film on the Cu surface decreased and the corrosion rate was relatively high.

[0085] Comparative Example 3 used N-(9-((1R,3R,4R,7S)-1-((bis(4-methoxyphenyl)(phenyl)methoxy)methyl)-7-hydroxy-2,5-dioxabicyclo[2.2.1]heptane-3-yl)-9H-purine-6-yl)benzamide as an additive, which weakened the conjugation effect with the chelating agent molecule and reduced the corrosion inhibition performance.

[0086] Comparative Example 4 uses p-hydroxyphenylacetamide as an organic modifier. Due to the lack of an S atom in the molecule, it reacts with Cu... 2+ The coordination ability of Cu is weakened, and the remaining Cu in the solution 2+ Increased levels lead to increased Cu-BTA production.

[0087] Comparative Example 5 used 2-hydroxybenzo-1-carbonthioamide as an organic regulator, which weakened the conjugation effect and led to an increase in the corrosion rate.

[0088] Further comparison can be made using the accompanying diagrams in the instruction manual:

[0089] Figure 1 Scanning electron microscope image of the copper sheet surface before cleaning, magnified 20,000 times. Figure 2 These are scanning electron microscope images magnified 20,000 times after cleaning with the cleaning agent of Example 1. Figure 3This is a scanning electron microscope image magnified 20,000 times after cleaning with the cleaning agent used in Comparative Example 1.

[0090] from Figure 1 It can be seen that there was obvious Cu-BTA residue on the surface of the Cu sheet before cleaning, and the corrosion was also quite severe; from Figure 2 It can be seen that after cleaning with the cleaning agent prepared in Example 1, the copper sheet surface is smooth and without residue, demonstrating a good cleaning effect. Figure 3 It can be seen that although the surface of the copper sheet was improved after cleaning with the cleaning agent prepared in Comparative Example 1 compared with the uncleaned surface, there was still obvious Cu-BTA residue and corrosion.

[0091] 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 agent for semiconductor chip polishing, characterized in that, Based on parts by weight, it includes the following components: 1-10 parts of additives; Chelating agent 1-10 parts; 1-5 parts organic regulator; 30-40 parts of solubilizer; 30-40 parts ultrapure water; The additive is an amine substance that contains both hydrophilic and hydrophobic groups.

2. The semiconductor chip polishing cleaning agent according to claim 1, characterized in that: The additive is one or more of 1-oleoyl-2-(12-biotin(aminododecanoyl))-sn-glycerol-3-phosphate ethanolamine, 1-(1Z-octadecenyl)-2-oleoyl-sn-glycerol-3-phosphate ethanolamine, and 1-palmitoyl-2-oleoylphosphatidylethanolamine.

3. The semiconductor chip polishing cleaning agent according to claim 1, characterized in that: The chelating agent is a compound containing both hydroxyl and carboxyl groups.

4. The semiconductor chip polishing cleaning agent according to claim 1 or 3, characterized in that: The chelating agent is Ganglioside GM3, (2R,3R,4R,5R)-5-acetamido-2,3-dihydroxy-6-oxo-4-(((2R,3R,4S,5R,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran, 8-hydroxyquinoline glucoside, 4-carboxy-6-hydroxy-2,2'-bipyrimidine are one or more of these.

5. The cleaning agent for semiconductor chip polishing according to claim 1, characterized in that: The organic regulator is an amine compound.

6. The semiconductor chip polishing cleaning agent according to claim 1 or 5, characterized in that: The organic regulator is one or more of 2-(1,3-benzothiazol-2-yl)acetamide, p-hydroxyphenylacetamide, and 2-hydroxybenzo-1-carbonthioamide.

7. The semiconductor chip polishing cleaning agent according to claim 1, characterized in that: The solubilizer is a strongly polar aprotic solvent.

8. A method for preparing a cleaning agent for semiconductor chip polishing according to 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 except ultrapure water to the container and stir at room temperature until all materials are completely dissolved. Finally, add ultrapure water and mix well to obtain the cleaning agent after semiconductor chip polishing.

9. A method of using the cleaning agent for semiconductor chip polishing according to any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Dilute the cleaning agent after polishing the semiconductor chip with ultrapure water, and then soak the chip at room temperature to obtain the soaked chip; Step 2: Rinse the soaked chip in ultrapure water at least twice to complete the cleaning process of the semiconductor chip. After cleaning, dry it with N2.

10. The use of the semiconductor chip polishing cleaning agent according to any one of claims 1-7 in cleaning semiconductor chips.

Images