Chemical mechanical polishing solution
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ANJI MICROELECTRONICS TECH (SHANGHAI) CO LTD
- Filing Date
- 2024-12-25
- Publication Date
- 2026-06-26
AI Technical Summary
In existing technologies, oxide nanoparticles have poor dispersion stability in organic acid environments, which can easily lead to problems such as scratches on the wafer surface. In particular, during chemical mechanical polishing, the abrasive particles agglomerate severely.
A betaine-type amphoteric surfactant was used as a dispersant to modify α-alumina particles in conjunction with anionic polymers. Through steric hindrance stabilization, the dispersion stability of the abrasive in an organic acid environment was improved.
This method achieves long-term stable dispersion of abrasives in acidic polishing slurry, improves the stability and polishing efficiency of the slurry, reduces wafer surface defects, and does not affect polishing performance.
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Abstract
Description
Technical Field
[0001] This invention relates to a chemical mechanical polishing slurry, and more particularly to a chemical mechanical polishing slurry for use in semiconductor material manufacturing processes. Background Technology
[0002] The rapid development of modern chip technology has greatly promoted the miniaturization of integrated circuit components. To ensure the normal distribution and effective operation of circuit components at the nanoscale, the planarization of the wafer surface must also reach a corresponding level. Currently, the most effective method to achieve this goal is chemical mechanical polishing (CMP) technology.
[0003] Chemical mechanical polishing (CMP) involves both chemical and mechanical processes. Typically, a wafer is fixed to a polishing head, with its front side in contact with a polishing pad in a CMP apparatus. Under pressure, the polishing head moves linearly across the polishing pad or rotates in the same direction as the polishing table. Simultaneously, a polishing composition ("slurry") is injected at a controlled flow rate between the wafer and the polishing pad, and the slurry spreads evenly on the polishing pad due to centrifugal force. Thus, through the combined chemical and mechanical action, the wafer surface is polished and globally planarized. During this process, the abrasive particles in the slurry must be uniformly and stably present in the system to ensure polishing stability; otherwise, scratches and other problems can easily occur on the wafer surface.
[0004] Abrasives are typically selected from relatively inert oxide nanoparticles, such as silicon oxide, alumina, titanium oxide, and cerium oxide. For different polishing systems, the abrasive particles usually need to be modified to meet specific polishing requirements. Patent CN 103946958B proposes a polishing composition containing α-alumina nanoparticles encapsulated by anionic copolymers, which can maintain long-term stability in acidic slurries containing organic acids. Similarly, patent CN 101978019B uses poly(2-acrylamido-2-methylpropanesulfonic acid) or polystyrene sulfonic acid to modify alumina particles, which exhibits good performance in polishing aluminum-copper alloys. Patent CN 1630697A discloses a method for treating anionic abrasive particles with a positively charged polyelectrolyte, which can obtain abrasives with a significantly positive Zeta(ζ) potential, effectively improving the stability of the polishing slurry and reducing the number of surface defects on the polishing substrate. Patent WO 01 / 02134A1 proposes that ionic species can adsorb onto the surface of abrasive particles, thereby effectively improving their dispersion stability. However, it does not further specify the effective types of ionic compounds, and their dispersion stability is generally poor. The modification effect of anionic polymers on abrasive particles is widely recognized and applied. However, during the treatment of abrasive particles with ionic polymers, the attraction between the ionic functional groups of the polymer and the surface charge of the abrasive easily leads to particle agglomeration. Therefore, this method often has relatively strict requirements for the processing technology. Summary of the Invention
[0005] To overcome the above-mentioned technical defects, this invention proposes a betaine-type amphoteric surfactant to promote the modification of positively charged α-alumina particles by anionic polymers, thereby achieving a dispersion effect and realizing the stable dispersion of abrasives in an organic acid environment.
[0006] Specifically, the present invention discloses a chemical mechanical polishing fluid, comprising: nano-α-alumina abrasive particles, dispersant, dispersing aid, organic carboxylic acid, oxidant, water and pH adjuster.
[0007] Preferably, the dispersing agent is an amphoteric surfactant containing both anionic and cationic hydrophilic groups.
[0008] Preferably, the cationic portion of the dispersing agent is composed of a quaternary ammonium group.
[0009] Preferably, the anionic functional group of the dispersing agent is selected from carboxyl, sulfonyl, or phosphate group.
[0010] Preferably, the dispersing agent is 3-(N,N-dimethyldodecylammonium)propane sulfonate, dodecyl dimethyl hydroxypropyl phosphate betaine, or lauryl dimethyl glycine acetate betaine.
[0011] Preferably, the dispersant is selected from anionic polymers containing sulfonic acid groups.
[0012] Preferably, the dispersant is a copolymer of poly(2-acrylamide-2-methyl-1-propanesulfonic acid) and acrylic acid-2-acrylamide-2-methylpropanesulfonic acid.
[0013] Preferably, the organic carboxylic acid is selected from one or more of lactic acid, succinic acid, malonic acid, tartaric acid, gluconic acid, phthalic acid, malic acid, and glycolic acid.
[0014] Preferably, the oxidant is selected from one or more of hydrogen peroxide and ferric nitrate.
[0015] Preferably, the pH adjuster is selected from ammonium hydroxide, potassium hydroxide, sodium hydroxide, nitric acid, and hydrochloric acid.
[0016] Preferably, the concentration range of the dispersing agent is 0.005wt%-0.5wt%, more preferably 0.005wt%-0.1wt%.
[0017] Preferably, the concentration range of the dispersant is 0.002wt%-3wt%, more preferably 0.005wt%-0.5wt%.
[0018] Preferably, the concentration of the nano-α-alumina particles ranges from 0.01wt% to 3wt%, more preferably from 0.01wt% to 1wt%.
[0019] Preferably, the concentration range of the organic carboxylic acid is 0.01 wt% to 5 wt%, more preferably 0.1 wt% to 3 wt%.
[0020] Preferably, the concentration of the oxidant is ≤4 wt%.
[0021] Preferably, the pH value of the polishing solution is 2-7.
[0022] The chemical mechanical polishing slurry disclosed in this invention mainly utilizes a betaine-type amphoteric surfactant containing both cationic and anionic hydrophilic groups, in conjunction with anionic polymers, to modify α-alumina particles with positively charged surfaces. This modification improves the stability of the suspension through a steric stabilization mechanism. The resulting dispersion slurry, obtained in an organic acid environment, maintains stability for an extended period without affecting the tungsten polishing performance. This invention solves the problem of dispersion stability of oxide particles with positively charged surfaces in an organic acid environment. The betaine-type amphoteric surfactant assists the anionic surfactant in modifying the abrasive surface, promoting particle dispersion while improving the stability of the polishing slurry, without affecting the polishing of tungsten. Detailed Implementation
[0023] The chemical mechanical polishing composition of the present invention will be described in detail below through specific embodiments to provide a better understanding of the present invention, but the following embodiments do not limit the scope of the present invention.
[0024] In the specific embodiments and comparisons, according to the formulations given in Table 1, all components were dissolved and mixed evenly, and water was added to bring the mass percentage to 100%. The pH was adjusted to the desired value using a pH adjuster.
[0025] In the examples, the percentages in the concentrations refer to mass percentage concentrations.
[0026] Table 1. Components and formulations of the embodiments and comparative examples of the present invention.
[0027]
[0028]
[0029] Note: C1: Poly(2-acrylamide-2-methyl-1-propanesulfonic acid); C2: Acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer; B1: 3-(N,N-dimethyldodecylammonium)propanesulfonate; B2: Dodecyl dimethyl hydroxypropyl phosphate betaine; B3: Laurodimethyl glycine acetate betaine.
[0030] The experiment was conducted according to the formula in Table 1 and the experimental conditions described below. The specific results are shown in Table 2.
[0031] Particle size determination: The particle size variation of the dispersion was analyzed using a Malvern particle size analyzer.
[0032] Specific polishing conditions: pressure 1.5psi, polishing disc and polishing head speed 93 / 87rpm, polishing pad Fujibo, polishing machine 12” Reflexion LK, polishing time 1min.
[0033] The optical velocity of a titanium nitride wafer was measured using a four-point probe metal material resistance meter, and the polishing speed of a silicon nitride wafer was measured using a semiconductor thin film thickness meter.
[0034] Table 2 shows the stability and polishing rate of tungsten in the examples and comparative examples.
[0035]
[0036]
[0037] The particle size of abrasive particles reflects their stability; smaller particles result in better stability of the polishing slurry (less prone to agglomeration and precipitation). Comparative Example 2 shows that in an acidic polishing slurry system, untreated alumina particles easily agglomerate and quickly precipitate. Comparative Example 3 shows that after treatment with anionic polymers, the abrasive particle size decreases, allowing for dispersion in the acidic polishing slurry. To further promote system dispersion and improve dispersion stability, dispersing aids are introduced.
[0038] Comparing Comparative Example 1 with Example 1, it was found that the average particle size of the alumina solution modified with the dispersant was 172 nm. After adding 3-(N,N-dimethyldodecylammonium)propane sulfonate dispersant, the particle size of the abrasive was reduced to 159 nm and remained stable for 180 days. This shows that the additive is beneficial to the dispersion effect of the alumina suspension.
[0039] Examples 2-5 show that in an acidic polishing slurry system, the betaine-type amphoteric surfactant proposed in this invention, as a dispersant, can effectively inhibit the agglomeration of anionic polymer-modified alumina particles and improve the stability of the suspension by providing steric hindrance. With increasing additive concentration, the particle size of the alumina particles gradually decreases, promoting dispersion. When the additive concentration reaches 0.1%, the particle size can reach 140 nm, and the polishing speed of tungsten is 991 A / min. Further increasing the additive concentration does not decrease the particle size; therefore, the preferred concentration range is 0.005%-0.3%.
[0040] Comparison of Example 3 with Examples 4, 6, and 7 shows that the addition of betaine-type amphoteric surfactants reduces the average particle size of the abrasive without significantly affecting the tungsten polishing speed. Among these, the polishing composition containing 3-(N,N-dimethyldodecylammonium)propane sulfonate dispersant exhibits a smaller average particle size and longer-term stability, demonstrating better dispersion stability, especially at an addition amount of 0.1%.
[0041] Examples 8-20 demonstrate that, under varying pH, abrasive particle concentration, dispersant concentration, type and concentration of organic acid, and oxidant concentration, the 3-(N,N-dimethyldodecylammonium)propane sulfonate dispersant exhibits good dispersion and stability in acidic polishing solutions. While the particle size of the polishing solution increases with increasing abrasive particle concentration, it remains lower than that of Comparative Example 3 without the dispersant. Examples 19-20 illustrate that the absence of an oxidant or the use of a single oxidant results in a low tungsten polishing speed, where mechanical polishing becomes the primary method.
[0042] A comparison of Example 4 and Comparative Examples 4-6 revealed that, in the acidic polishing slurry system, 3-(N,N-dimethyldodecylammonium)propane sulfonate effectively promoted the modification and dispersion of alumina particles by the anionic polymer, showing better results than the nonionic surfactant polyethylene glycol, the anionic surfactant dodecylbenzenesulfonic acid, and the cationic surfactant tetrabutylammonium nitrate. In summary, the introduction of the betaine-type amphoteric surfactant in this patent can promote the dispersion of alumina particles by the anionic polymer, and 3-(N,N-dimethyldodecylammonium)propane sulfonate can further reduce the average particle size of nanoparticles in the system and maintain the long-term stability of the polishing slurry.
[0043] 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 chemical mechanical polishing slurry, characterized in that, include: Nano-alumina abrasive particles, dispersant, dispersing aid, organic carboxylic acid, oxidant, water, and pH adjuster.
2. The polishing slurry as described in claim 1, characterized in that, The dispersing agent is an amphoteric surfactant containing both anionic and cationic hydrophilic groups.
3. The polishing slurry as described in claim 2, characterized in that, The cationic portion of the dispersing agent is composed of quaternary ammonium groups.
4. The polishing slurry as described in claim 3, characterized in that, The anionic functional group of the dispersing agent is selected from carboxyl, sulfonyl, or phosphate group.
5. The polishing slurry as described in claim 4, characterized in that, The dispersing agent is 3-(N,N-dimethyldodecylammonium)propane sulfonate, dodecyl dimethyl hydroxypropyl phosphate betaine, and lauryl dimethyl glycine acetate betaine.
6. The polishing slurry as described in claim 1, characterized in that, The dispersant is selected from anionic polymers containing sulfonic acid groups.
7. The polishing slurry as described in claim 6, characterized in that, The dispersant is a copolymer of poly(2-acrylamide-2-methyl-1-propanesulfonic acid) and acrylic acid-2-acrylamide-2-methylpropanesulfonic acid.
8. The polishing slurry as described in claim 1, characterized in that, The organic carboxylic acid is selected from one or more of lactic acid, succinic acid, malonic acid, tartaric acid, gluconic acid, phthalic acid, malic acid, and glycolic acid.
9. The polishing slurry as described in claim 1, characterized in that, The oxidant is selected from one or more of hydrogen peroxide and ferric nitrate.
10. The polishing slurry as described in claim 1, characterized in that, The pH adjuster is selected from ammonium hydroxide, potassium hydroxide, sodium hydroxide, nitric acid, and hydrochloric acid.
11. The polishing slurry as described in claim 1, characterized in that, The concentration range of the dispersing agent is 0.005 wt% to 0.5 wt%.
12. The polishing slurry as described in claim 11, characterized in that, The concentration range of the dispersing agent is 0.005 wt% to 0.1 wt%.
13. The polishing slurry as described in claim 1, characterized in that, The concentration range of the dispersant is 0.002 wt% to 3 wt%.
14. The polishing slurry as described in claim 13, characterized in that, The concentration range of the dispersant is 0.005 wt% to 0.5 wt%.
15. The polishing slurry as described in claim 1, characterized in that, The concentration range of the nano-α-alumina particles is 0.01wt%-3wt%.
16. The polishing slurry as described in claim 15, characterized in that, The concentration range of the nano-α-alumina particles is 0.01wt%-1wt%.
17. The polishing slurry as described in claim 1, characterized in that, The concentration range of the organic carboxylic acid is 0.01 wt% to 5 wt%.
18. The polishing slurry as described in claim 17, characterized in that, The concentration range of the organic carboxylic acid is 0.1 wt% to 3 wt%.
19. The polishing slurry as described in claim 1, characterized in that, The concentration range of the oxidant is ≤4 wt%.
20. The polishing slurry as described in claim 1, characterized in that, pH value is 2-7.