A low metal ion residual post-cmp cleaning agent for chips, its preparation method and application

Abstract

The present application relates to a kind of low metal ion residual chip CMP post-cleaning agent and preparation method and application.The cleaning agent includes the following components according to weight part: functional agent 8-35 parts;Chelating agent 5-15 parts;pH adjusting agent 5-20 parts;Corrosion inhibitor 0.1-1 parts;Water 30-70 parts.The present application uses the symmetrical carbon skeleton structure of triphenylene with high chemical stability as functional agent, through the combination of functional agent and chelating agent, to achieve the effect of efficiently cleaning copper wafer surface residues and quickly dissolving metal oxides.The cleaning agent of the present application is environmentally friendly, non-polluting, and has low volatile loss, and is harmless to the environment and human body.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor manufacturing processes, and particularly relates to a low-metal-ion residue chip post-CMP cleaning agent, its preparation method, and its application. Background Technology

[0002] As the design and manufacturing level of very large-scale integrated circuits (GLSI) continues to improve and their feature size continues to shrink, the RC delay of metal interconnect wiring and the device reliability problems caused by metal electromigration have gradually become the main contradictions affecting circuit performance.

[0003] Copper (Cu) has replaced aluminum as the mainstream material for interconnect wiring in integrated circuits due to its superior resistance to electromigration and lower resistivity. In the back-end processes of Cu semiconductor chip manufacturing, chemical mechanical polishing (CMP) is used to remove excess copper and barrier layers. While achieving a highly planarized wafer surface, the polished copper wafer surface is highly reactive, easily adsorbing impurities from the surrounding environment to reduce energy. The polishing slurry contains a large number of nanoscale abrasives and chemicals, and the added oxidant oxidizes the surface copper, forming an oxide layer that is easily removed under chemical and mechanical action. This, in turn, easily generates more metal ions, all of which need to be thoroughly and effectively removed by a post-CMP cleaning process to obtain a defect-free, contamination-free wafer surface. After cleaning, the wafer must pass inspection before proceeding to the next process. Therefore, the quality of the cleaning has a significant impact on the smooth progress of the back-end processes and the chip's performance and yield.

[0004] The main purpose of post-CMP cleaning for copper interconnects is to remove residues from the copper surface after CMP. Residual metal ions increase the resistance of copper interconnects, leading to increased RC delay, which severely impacts device performance and can even cause device failure, ultimately reducing yield. Therefore, developing novel cleaning agents that improve the effectiveness of metal ion removal is crucial for improving product yield. Summary of the Invention

[0005] The technical problem solved by this invention is the removal of residual metal ions from the chip surface after CMP in the post-CMP cleaning process.

[0006] In view of the technical problems existing in the prior art, this invention designs a low-metal-ion residual chip CMP post-cleaning agent, its preparation method, and its application. The low-metal-ion residual chip CMP post-cleaning agent can quickly remove residual metal ions on the chip surface after CMP, reduce corrosion to the substrate, and maintain extremely excellent cleaning efficiency even under pure immersion cleaning conditions without the need for ultrasonic cleaning.

[0007] 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.

[0008] To solve the aforementioned technical problems, the present invention adopts the following solution:

[0009] A low-metal ion residue chip CMP post-cleaning agent, comprising the following components by weight:

[0010]

[0011] The functional agent is a triterpenoid compound;

[0012] The chelating agent is a glycosyl phosphate compound;

[0013] The corrosion inhibitor is a heterocyclic compound containing heteroatoms.

[0014] Furthermore, the tripterene compound is one or more of 2,6,14-triaminotripterene, 2,3,6,7,14,15-hexahydroxytripterene, and quaternized tripterene hypercrosslinked polymers.

[0015] Furthermore, the chelating agent is one or more of D-glucose-6-phosphate, xylose uridine diphosphate, and galactose-1-phosphate.

[0016] Furthermore, the mass ratio of the functional agent to the chelating agent is 8-35:5-15.

[0017] Furthermore, the preferred mass ratio of the functional agent to the chelating agent is 14-24:8-12.

[0018] Furthermore, the pH adjuster is one or more of acrylic acid-maleic acid copolymer, methyl vinyl ether-maleic anhydride copolymer, and poly(lactic acid-glycolic acid) copolymer.

[0019] Further, the corrosion inhibitor is one or more of 5-hydroxyquinoline, 2-amino-1,3,4-thiadiazole, 1H-imidazol-4-carboxylic acid, 2-hydroxymethylpyrazine, and 2,3-pyridinedicarboxylic acid.

[0020] Furthermore, the cleaning agent used after chip CMP is acidic.

[0021] Furthermore, the pH of the cleaning agent used after chip CMP is 2-6.

[0022] The present invention also discloses a method for preparing a post-CMP cleaning agent for chips with low metal ion residue, comprising the following steps: weighing each component according to the weight parts, then mixing all components evenly and stirring until all materials are completely dissolved, thereby obtaining the post-CMP cleaning agent for chips with low metal ion residue.

[0023] This invention also discloses a cleaning method for chips with low metal ion residue after CMP using a cleaning agent, comprising the following steps:

[0024] Step 1: Prepare an aqueous solution with a mass percentage concentration of 10-100% using ultrapure water with the low metal ion residual chip CMP cleaning agent. Then, soak the chip in the above aqueous solution at room temperature for 1-5 minutes to obtain the soaked chip.

[0025] Step 2: Rinse the soaked chip in ultrapure water at least twice to complete the chip cleaning process.

[0026] The present invention also discloses the use of a low-metal-ion residual chip CMP cleaning agent in cleaning the metal ions remaining on the surface of copper wafers after CMP in the Cu process.

[0027] In this invention, the weight percentages of each component in the post-CMP cleaning agent for low-metal-ion residual chips can be further optimized as follows: 14-24 parts of functional agent; 8-12 parts of chelating agent; 10-15 parts of pH adjuster; 0.2-0.5 parts of corrosion inhibitor; and 40-60 parts of water. The water is one or more of deionized water, distilled water, and ultrapure water, preferably ultrapure water.

[0028] In this invention, in order to further optimize the effect of the cleaning agent, the functional agent is preferably a quaternized tripterene hypercrosslinked polymer; the chelating agent is most preferably xylose diphosphate uridine; the pH adjuster is preferably an acrylic acid-maleic acid copolymer; and the corrosion inhibitor is preferably 2,3-pyridinedicarboxylic acid.

[0029] In this invention, the pH of the cleaning agent after CMP of low metal ion residue chip can be further preferably 3.5-5.5.

[0030] The inventors have discovered that the functional agent of this invention has multiple functions, including cleaning and wetting stabilization:

[0031] Its cleaning function is to accelerate the dissolution of the oxide layer on the copper surface in the system, and to have a strong chelating effect on copper metal ions in the solution. It reacts with copper ions to form a stable and soluble complex, which is carried away from the surface by the flowing cleaning agent. It and the copper amine complex product are easily soluble in water and organic solvents, and will not introduce ion contamination.

[0032] Its dissolving and wetting properties can enhance the adsorption characteristics on solid surfaces, reduce the surface tension of the cleaning agent, and allow the cleaning agent to have more sufficient contact with the surface being cleaned. The electron-rich cavities of tripterene and the binding affinity of cations enhance its coordination with copper ions, thereby enhancing the stability of the formed complex and making the cleaning more thorough.

[0033] Furthermore, the highly chemically stable symmetrical carbon skeleton structure of the tripterene endows it with excellent stabilizer properties in this system, thereby ensuring the uniform mixing of the entire system.

[0034] The inventors have discovered that the chelating agent of this invention has a unique function:

[0035] Firstly, it has a strong complexing effect on copper metal ions, reacting with copper ions on the wafer surface to form stable and soluble complexes that are then removed from the surface by the cleaning agent.

[0036] Secondly, while accelerating the dissolution of the oxide layer, it slows down the corrosion of the substrate by the acid, inhibits the diffusion of hydrogen atoms into the substrate, and ensures that the metal surface is smooth and flat.

[0037] In this invention, the pH adjuster can also be used as an adjuvant to chelate copper metal ions in the solution and enhance the cleaning effect.

[0038] In this invention, the corrosion inhibitor can be adsorbed onto the metal surface to form a passivation film. The surface of the corrosion inhibitor is not easily wetted and has good hydrophobicity, thereby achieving the effect of inhibiting metal corrosion.

[0039] This invention provides a low-metal ion residue chip CMP post-cleaning agent, its preparation method, and its application, which have the following characteristics: Beneficial effects :

[0040] (1) The functional agent used in this invention has a quaternary ammonium modified with a highly chemically stable triterpenoid symmetrical carbon skeleton structure, which has the properties of a cleaning agent and a stabilizer. It can accelerate the dissolution of the oxide layer on the copper surface and has a strong chelating effect on copper ions in the solution. It reacts with copper ions to generate a stable and soluble complex to achieve the effect of efficiently cleaning the residues on the surface of copper wafers.

[0041] (2) The functional agent and chelating agent of the present invention are combined to achieve the synergistic effect of chelating copper metal ions, thereby rapidly dissolving metal oxides such as copper oxide and cuprous oxide, avoiding acid corrosion of the substrate, and ensuring the smoothness and flatness of the copper wafer surface after cleaning.

[0042] (3) The cleaning agent of the present invention is environmentally friendly, pollution-free, and has low volatilization loss. After cleaning, it can be rinsed with pure water only, which is harmless to the environment and human body. Attached Figure Description

[0043] Figure 1This is a 50x magnified image of the copper wafer before cleaning in this invention.

[0044] Figure 2 Image : A 50x magnified image of a copper wafer after being soaked in the cleaning agent prepared in Example 1 of this invention.

[0045] Figure 3 : This is a 50x magnified image under a microscope of a copper wafer after it has been soaked in the cleaning agent prepared in Comparative Example 2 of this invention. Detailed Implementation

[0046] The present invention will be further described below with reference to specific embodiments and accompanying drawings:

[0047] Table 1 Examples 1-7

[0048]

[0049] Table 2 Comparative Examples 1-3

[0050]

[0051] The preparation method of the low-metal ion residual chip CMP post-cleaning agent of the present invention includes the following steps:

[0052] The preparation method of the low metal ion residual chip CMP cleaning agent involved in Examples 1-7 and Comparative Examples 1-3 above is as follows:

[0053] Step 1: Weigh out the respective amounts of functional agent, chelating agent, pH adjuster, corrosion inhibitor, and water;

[0054] Step 2: Add all components to the container and stir until all materials are completely dissolved to obtain the low metal ion residue chip CMP post-cleaning agent.

[0055] The cleaning method for low-metal-ion-residue chips after CMP includes the following steps:

[0056] Step 1: Prepare an aqueous solution with a mass percentage concentration of 85% using ultrapure water with the low metal ion residual chip CMP cleaning agent. Then, soak the copper wafer in the above aqueous solution at room temperature for 3 minutes to obtain the soaked copper wafer.

[0057] Step 2: Rinse the soaked copper wafer in ultrapure water at least twice to complete the cleaning process of the copper wafer.

[0058] The chip involved in this application is a copper wafer.

[0059] Regarding performance testing and explanation:

[0060] Test method for surface tension of performance 1:

[0061] Platinum Plate Method

[0062] A drop of cleaning agent is placed in a petri dish and then in a surface tension meter. When the platinum plate is immersed in the liquid, surface tension acts around it, pulling the plate downwards. Once the surface tension and other related forces reach equilibrium, the platinum plate stops immersing itself. At this point, the surface tension meter's equilibrium sensor measures the immersion depth and converts it into the surface tension value. The reading is taken after the value stabilizes.

[0063] Test method for contact angle performance 2:

[0064] Deionized water is dropped onto the surface of a copper wafer, and the angle is analyzed using a contact angle meter to determine the hydrophilicity and hydrophobicity of the copper wafer surface. The degree of copper ion removal is then assessed based on the hydrophilicity and hydrophobicity of the copper wafer surface.

[0065] Fresh copper wafers have a hydrophilic surface, resulting in a small contact angle for deionized water. However, when copper contamination is present on the surface, the surface becomes hydrophobic, leading to a large contact angle for deionized water.

[0066] Test method for performance 3 cleaning effect:

[0067] After the chemical mechanical polishing process of the later-stage Cu process, copper wafers with silicon carbide as substrates have a large amount of residual metal ions, organic matter, particles, etc. The wafers are cleaned using the cleaning agents described in the above embodiments and comparative examples of this invention. The cleaning method includes the following steps:

[0068] Step 1: Place the... Low metal ion residue chip CMP post-cleaning agent An aqueous solution with a mass percentage concentration of 85% was prepared using ultrapure water. The copper wafer was then soaked in the aqueous solution at room temperature for 3 minutes to obtain the soaked wafer.

[0069] Step 2: Rinse the soaked copper wafer in ultrapure water at least twice to complete the cleaning process. Observe under a microscope to see if there are any residues after cleaning.

[0070] The ultrapure water used in steps 1 and 2 is deionized water with a resistance of at least 18 MΩ.

[0071] Table 3 Test Data

[0072]

[0073]

[0074] Analysis and explanation of the test results:

[0075] As can be seen from Table 3, the cleaning agents prepared in Examples 1-7 of this invention can efficiently clean the residues on the surface of copper wafers in a short time, reduce surface tension and decrease contact angle, proving that the cleaning agents in the examples all have good hydrophilicity on the surface of copper wafers; while the cleaning agents in the comparative examples have poorer hydrophilicity.

[0076] A comparison of Example 1 and Comparative Examples 1-3 shows that, compared with Example 1, no chelating agent was added. Due to the large amount of residual metal ions adsorbed on the wafer surface, the surface tension of the cleaning agent increased, the bonding force with the copper wafer weakened, the cleaning was not thorough, and the contact angle increased.

[0077] Compared with Example 1, the replacement of the quaternized tripterene hypercrosslinked polymer with choline hydroxide resulted in a decrease in the binding ability of copper ions, leading to an increase in the surface tension of the cleaning agent, incomplete cleaning, and a larger contact angle.

[0078] Compared with Example 1, Comparative Example 3 used acrylic acid alone as a pH adjuster. As the effect of the cleaning agent binding copper ions decreased, the surface tension of the cleaning agent increased, the cleaning effect deteriorated, and the contact angle increased.

[0079] Further comparison can be made using the accompanying drawings in the instruction manual. :

[0080] Figure 1 This is a 50x magnified image of the copper wafer before cleaning in this invention.

[0081] Figure 2 This is a 50x magnified image under a microscope of a copper wafer after it has been soaked in the cleaning agent prepared in Example 1 of this invention.

[0082] Figure 3 This is a 50x magnified image under a microscope of a copper wafer after it has been soaked in the cleaning agent prepared in Comparative Example 2 of this invention.

[0083] Combination Figure 1 and Figure 2 , Figure 3 It can be seen that, Figure 1 The copper wafer surface is covered with a large number of black spots of Cu contamination residue. The adsorption on the surface of the copper wafer makes it highly hydrophobic, which proves that there are copper ion residues on the surface of the copper wafer. Figure 2 The clean surface of the copper wafer indicates that no copper contamination residue remained after cleaning with the cleaning agent prepared in Example 1. Figure 3 Although compared to Figure 1 The number of black spots has decreased, but compared to Figure 2 The presence of residual contaminants indicates that the copper wafers were not properly cleaned using the cleaning agent prepared in Comparative Example 2.

[0084] This invention utilizes a highly chemically stable tripterene symmetrical carbon skeleton structure modified with quaternary ammonium ions as a functional agent. The combination of tripterene compounds as functional agents and glycosyl phosphate compounds as chelating agents accelerates the dissolution of the oxide layer on copper surfaces and exhibits a strong chelating effect on copper ions in solution. It reacts with copper ions to form stable and soluble complexes, achieving highly efficient cleaning of residues on copper wafer surfaces. The synergistic effect of chelating copper metal ions rapidly dissolves metal oxides, providing both cleaning agent and stabilizer properties. The cleaning agent of this invention is environmentally friendly, pollution-free, and has low volatilization loss, posing no harm to the environment or human health.

[0085] 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 low-metal ion residue chip CMP post-cleaning agent, characterized in that, Based on parts by weight, it includes the following components: Functional agent 8-35 parts; Chelating agent 5-15 parts; 5-20 parts of pH adjuster; Corrosion inhibitor 0.1-1 part; 30-70 parts water; The functional agent is a triterpenoid compound; The chelating agent is a glycosyl phosphate compound; The corrosion inhibitor is a heterocyclic compound containing heteroatoms; The pH adjuster is one or more of acrylic acid-maleic acid copolymer, methyl vinyl ether-maleic anhydride copolymer, and poly(lactic acid-glycolic acid) copolymer.

2. The low-metal-ion-residue chip CMP post-cleaning agent according to claim 1, characterized in that: The tripterene compound is one or more of 2,6,14-triaminotripterene, 2,3,6,7,14,15-hexahydroxytripterene, and quaternized tripterene hypercrosslinked polymers.

3. The low-metal-ion-residue chip CMP post-cleaning agent according to claim 1, characterized in that: The chelating agent is one or more of uridine diphosphate xylose, D-glucose-6-phosphate, and galactose-1-phosphate.

4. The low-metal-ion-residue chip CMP post-cleaning agent according to claim 1, characterized in that: The corrosion inhibitor is one or more of 5-hydroxyquinoline, 2-amino-1,3,4-thiadiazole, 1H-imidazol-4-carboxylic acid, 2-hydroxymethylpyrazine, and 2,3-pyridinedicarboxylic acid.

5. The low-metal-ion-residue chip CMP post-cleaning agent according to claim 1, characterized in that: The cleaning agent used after CMP for the low metal ion residue chip is acidic.

6. The low-metal-ion-residue chip CMP post-cleaning agent according to claim 5, characterized in that: The pH of the cleaning agent used after CMP of the chip is 2-6.

7. A method for preparing a post-CMP cleaning agent for low-metal ion residue chips according to any one of claims 1-6, characterized in that... The process includes the following steps: weighing each component according to the specified weight, mixing all components evenly, and stirring until all components are completely dissolved to obtain the low metal ion residue chip CMP post-cleaning agent.

8. A cleaning method for a chip CMP cleaning agent with low metal ion residue as described in any one of claims 1-6, characterized in that... Includes the following steps: Step 1: Prepare an aqueous solution with a mass percentage concentration of 10-100% using ultrapure water with the low metal ion residual chip CMP cleaning agent. Then, soak the chip in the above aqueous solution at room temperature for 1-5 minutes to obtain the soaked chip. Step 2: Rinse the soaked chip in ultrapure water at least twice to complete the chip cleaning process.

9. The use of the low metal ion residue chip CMP cleaning agent according to any one of claims 1-6 in cleaning the metal ions remaining on the surface of copper wafers after CMP in the Cu process.

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