A cleaning solution after chemical mechanical polishing

Abstract

This invention discloses a water-based cleaning solution comprising: an organic solvent that is poorly soluble in water, a water-soluble co-solvent, a pH adjuster, and water. The organic solvent that is poorly soluble in water is an aromatic hydrocarbon, a halogenated hydrocarbon, or an ester. This cleaning solution, rich in a highly dissolving organic solvent, can rapidly and efficiently remove organic residues and polymers after polishing, while exhibiting excellent stability. Thanks to its unique formulation and efficient cleaning capabilities, the cleaning solution of this invention shows broad application prospects in fields such as semiconductor wafer cleaning.

Description

Technical Field

[0001] This invention relates to a cleaning solution, and more particularly to a cleaning solution for chemical mechanical polishing. Background Technology

[0002] In device manufacturing, chemical mechanical polishing (CMP) is a core technology for wafer planarization. Metal CMP slurries typically consist of various components, including abrasive particles, complexing agents, metal corrosion inhibitors, oxidants, and dispersants. The abrasive particles mainly include silicon dioxide, aluminum oxide, aluminum-doped or aluminum-coated silicon dioxide, cerium dioxide, titanium dioxide, and polymeric abrasive particles. After the metal CMP process, the wafer surface is often contaminated by metal ions and abrasive particles from the polishing slurry. This contamination not only adversely affects the electrical properties of semiconductors but also reduces device reliability. Residual metal ions, abrasive particles, and organic matter all affect the flatness of the wafer surface, potentially weakening device performance and even negatively impacting subsequent processes or device operation. Therefore, after the metal CMP process, removing residual metal ions, organic matter, and abrasive particles from the wafer surface, improving the hydrophilicity of the cleaned wafer surface, and reducing surface defects are particularly important.

[0003] Currently, CMP post-cleaning solutions primarily contain water-soluble organic solvents. However, these solvents have limited dissolving power for some difficult-to-dissolve organic compounds or polymers. While some organic solvents are not readily soluble in water, they possess extremely strong dissolving power. Therefore, we need to develop a broad-spectrum cleaning solution that can effectively incorporate water-insoluble organic solvents to address the issue of organic residue after polishing. This cleaning solution will be able to more comprehensively remove contaminants from the wafer surface, ensuring device performance and reliability. Summary of the Invention

[0004] In order to overcome the above-mentioned technical defects, the present invention aims to provide a cleaning solution after chemical mechanical polishing, comprising: an organic solvent that is not easily soluble in water, a co-solvent that is soluble in water, a pH adjuster, and water.

[0005] Furthermore, the organic solvent that is not easily soluble in water is an aromatic hydrocarbon solvent, a halogenated hydrocarbon solvent, or an ester solvent.

[0006] Furthermore, the aromatic hydrocarbon solvent is a compound linked to a methyl or ester group.

[0007] Furthermore, the halogenated hydrocarbon solvent is a chlorine-containing compound.

[0008] Furthermore, the ester solvent is an acetate or propionate compound.

[0009] Furthermore, the organic solvent that is not readily soluble in water is chloroform, methyl benzoate, ethyl acetate, methyl p-methylbenzoate, toluene, 1,2-dichloroethane, or dichloromethane.

[0010] Furthermore, the concentration range of the organic solvent that is not easily soluble in water is 0.05% to 0.2wt%.

[0011] Furthermore, the water-soluble co-solvent is an ether, alcohol, ketone, nitrile, or a mixture thereof.

[0012] Furthermore, the water-soluble co-solvent is 1,4-dioxane, acetone, or acetonitrile.

[0013] Furthermore, the concentration range of the water-soluble co-solvent is 1% to 4 wt%.

[0014] Furthermore, the mass ratio of the organic solvent that is not easily soluble in water to the co-solvent that is soluble in water is 1:10 to 1:40.

[0015] Furthermore, the pH adjuster is an organic acid, inorganic acid, organic base, or inorganic base; preferably nitric acid or ammonia.

[0016] Furthermore, the pH value of the cleaning solution is 4 to 9.

[0017] The core of post-polishing cleaning solutions lies in the addition of water-soluble compounds to ensure excellent cleaning results. However, some compounds in polishing solutions have low solubility in water or common soluble compounds after polishing, often leading to residue problems. The core of this invention is the introduction of a special solvent that, while immiscible with water, has extremely high solubility for organic matter. Simultaneously, a co-solvent is added to help achieve a homogeneous state in the cleaning solution. This unique combination not only solves the problem of poor dissolution of polishing compounds but also significantly improves the cleaning effect, enabling the cleaning solution to more thoroughly remove polishing residues. In short, this invention, through the combined use of a selected solvent and co-solvent, achieves both homogeneous stability of the cleaning solution and ensures excellent cleaning results, thus effectively solving the problem of post-polishing residues. Detailed Implementation

[0018] The cleaning solution of the present invention will be described in detail below through specific embodiments to enable a better understanding of the present invention, but the following embodiments do not limit the scope of the present invention.

[0019] In the specific embodiments and comparative examples, according to the formulations given in Table 1, all components were mixed evenly, and the pH was adjusted to the desired value using a pH adjuster.

[0020] Table 1. Composition and content of the examples and comparative examples

[0021]

[0022]

[0023] Note: Cleaning solution A consists of 5% citric acid and 0.5% ethylenediaminetetraacetic acid; cleaning solution B consists of 5% monoethanolamine and 0.5% ethylenediaminetetraacetic acid.

[0024] The experiment was conducted according to the formula in Table 1 and the experimental conditions described below. The results are shown in Table 2.

[0025] Specific polishing conditions: pressure 2.0 psi, polishing disc and head speed 110 / 85 rpm, polishing pad Fujibo, polishing fluid flow rate 200 mL / min, polishing machine 12” Reflexion LK, polishing time 1 min. After polishing, clean with appropriate cleaning solution, and measure defects using SP2.

[0026] Table 2. Number of defects in the examples and comparative examples.

[0027] Polishing liquid Number of defects Example 1 3587 Example 2 3844 Example 3 3198 Example 4 4059 Example 5 2805 Example 6 524 Example 7 468 Example 8 310 Example 9 258 Example 10 190 Example 11 756 Example 12 472 Example 13 610 Example 14 480 Example 15 511 Example 16 386 Example 17 459 Example 18 412 Example 19 562 Example 20 557 Example 21 620 Example 22 480 Example 23 2955 Example 24 542 Example 25 608 Example 26 362 Example 27 426 Comparative Example 1 9566 Comparative Example 2 4315 Comparative Example 3 5260

[0028] Examples 1-21 demonstrate that the cleaning solution of the present invention performs excellently when cleaning polished wafers, significantly reducing the number of defects. By adjusting the content and ratio of organic solvent and co-solvent, even better cleaning performance can be achieved. Depending on the specific product and process requirements, a lower defect count is generally better. In practice, a count below 1000 is generally preferable, but for some products, a higher count is also acceptable.

[0029] By comparing Comparative Example 1 and Examples 1-4, it was found that when organic solvents and co-solvents were introduced into the water-based conventional cleaning solution, not only was the cleaning efficiency greatly improved, but the number of residual defects also decreased as the proportion of organic solvents increased.

[0030] A comparison with Comparative Example 2 and Examples 6-8 demonstrates that applying organic solvents at different concentrations in practice confirms that increasing the proportion of organic solvents helps improve cleanliness and reduce the number of defects.

[0031] Examples 8-10 show that increasing the proportion of co-solvent can effectively promote better dispersion of organic components in water, thereby achieving better cleaning results.

[0032] Examples 10-12 show that whether aromatic hydrocarbons, halogenated hydrocarbons, or ester compounds are used as the main active ingredients, they all exhibit excellent cleaning performance.

[0033] Examples 11-17 show that different types of organic solvents and co-solvents all have good cleaning effects.

[0034] The comparison with Comparative Example 3 and Example 18 shows that the number of defects in the alkaline cleaning solution was significantly reduced after the addition of organic solvents and co-solvents.

[0035] The cleaning solution of this invention successfully combines a co-solvent with a solvent that is not readily soluble in water, thus effectively adding a solvent that is originally not soluble in water to the cleaning solution. The key to this innovation lies in the fact that the newly added solvent has excellent solubility for organic matter, which greatly enhances the overall cleaning ability of the cleaning solution, thereby achieving a more thorough cleaning effect.

[0036] It should be noted that the embodiments of the present invention have better implementability and are not intended to limit the present invention in any way. Any person skilled in the art may use the above-disclosed technical content to change or modify it into equivalent effective embodiments. However, any modifications or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A cleaning solution after chemical mechanical polishing, characterized by, include: An organic solvent that is not readily soluble in water, a cosolvent that is soluble in water, a pH adjuster, and water.

2. The cleaning solution of claim 1, wherein The organic solvents that are not easily soluble in water are aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, and ester solvents.

3. The cleaning solution of claim 2, wherein The aromatic hydrocarbon solvent is a compound linked to a methyl or ester group.

4. The cleaning solution as described in claim 2, characterized in that, The halogenated hydrocarbon solvent is a chlorine-containing compound.

5. The cleaning solution of claim 2, wherein The ester solvent is an acetate or propionate compound.

6. The cleaning solution of claim 2, wherein The organic solvents that are not easily soluble in water are chloroform, methyl benzoate, ethyl acetate, methyl p-methylbenzoate, toluene, 1,2-dichloroethane, and dichloromethane.

7. The cleaning solution as described in claim 1, characterized in that, The concentration range of the organic solvent that is not easily soluble in water is 0.05% to 0.2 wt%.

8. The cleaning solution of claim 1, wherein The water-soluble cosolvents are ethers, alcohols, ketones, nitriles, and mixtures thereof.

9. The cleaning solution of claim 8, wherein The water-soluble co-solvents are 1,4-dioxane, acetone, and acetonitrile.

10. The cleaning solution of claim 1, wherein The concentration range of the water-soluble co-solvent is 1% to 4 wt%.

11. The cleaning solution of claim 1, wherein The mass ratio of the organic solvent that is not easily soluble in water to the co-solvent that is soluble in water is 1:10 to 1:

40.

12. The cleaning solution of claim 1, wherein The pH adjuster is an organic acid, an inorganic acid, an organic base, or an inorganic base.

13. The cleaning solution as described in claim 1, characterized in that, The pH adjuster is nitric acid or ammonia.

14. The cleaning solution of claim 1, wherein The pH value of the cleaning solution is 4 to 9.

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