Cleaning composition

Abstract

Disclosed in the present invention is an alkaline cleaning composition comprising a complexing agent, an organic amine compound, and a pH adjusting agent. The addition of a complexing agent enables same to form a complexing bond with cerium oxide, inhibiting the combination of cerium oxide and a silicon oxide surface, and having the function of reversing the charge of the positively charged cerium oxide particles, such that the cerium oxide particles and the wafer surface form a strong repulsive effect under alkaline conditions. The addition of the organic amine compound can improve the ability of the cleaning solution to remove cerium oxide particles. The cleaning composition disclosed in the present invention can effectively remove cerium oxide particles adhered to the surface of TEOS, and after cleaning, the number of particles observed under SEM characterization is less than 3.

Description

A cleaning composition Technical Field

[0001] This invention relates to an alkaline cleaning solution, and more particularly to a cleaning solution for cleaning cerium oxide particles adhering to the surface of TEOS wafers. Background Technology

[0002] In semiconductor device manufacturing, chemical mechanical polishing (CMP) has become the most effective and mature planarization technology. Among CMP slurries based on different abrasive grains, cerium oxide particles can still provide high polishing rates at lower concentrations, while cerium oxide slurries offer higher selectivity, making them valuable in CMP applications. However, compared to silicon dioxide particles, cerium oxide particles have a higher affinity for the silicon dioxide (TEOS) wafer surface, easily forming Ce-O-Si bonds and making them difficult to remove. Adhesion of particles to the wafer surface severely impacts subsequent chip manufacturing processes and reduces yield. Therefore, developing a cleaning solution that can effectively reduce and remove cerium oxide particles from the wafer surface is a pressing issue.

[0003] Studies on the cleaning ability of cleaning solutions on wafer surfaces after CMP treatment typically employ equipment and process conditions comparable to those used in chip manufacturing. After polishing on a CMP machine (such as Reflexion LK or Ebara), the wafer is cleaned with a cleaning solution (e.g., via on-plate buff or brushing), dried, and then the total number of defects on the wafer surface is detected using a wafer defect detection system (such as SURFSCAN SP2 / SP5 / SP7). The defects are then analyzed and classified using an eDR device to evaluate the cleaning solution's ability to clean particles. However, this method requires expensive production equipment, large quantities of cleaning solution and wafers, resulting in high costs and hindering the rapid selection of cleaning solutions.

[0004] This invention employs a laboratory evaluation method, dicing wafers into small wafer samples for contamination experiments to obtain samples to be cleaned. The contaminated samples are then cleaned with a cleaning solution. The samples before and after cleaning are characterized using SEM to determine the amount of particulate contaminants. Through rapid screening of the cleaning solution, this invention provides a cleaning solution that can effectively remove cerium oxide particles adhering to the surface of TEOS wafers. Summary of the Invention

[0005] The present invention discloses a cleaning composition comprising: a complexing agent, an organic amine compound, and a pH adjuster.

[0006] Further, the complexing agent includes one or more of the following: hydroxyethylidene diphosphonic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, aminotrimethylenephosphonic acid, ethylenediaminetetraacetic acid, polyacrylic acid, and dipotassium hydrogen phosphate.

[0007] Furthermore, the organic amine compound includes: ethanolamine and diethylene glycolamine.

[0008] Furthermore, the pH adjuster includes: KOH, tetrabutylammonium hydroxide, or choline hydroxide.

[0009] Furthermore, the concentration range of the complexing agent is 0.066wt%-1wt%.

[0010] Furthermore, the concentration range of the organic amine is 0.2 wt% to 5 wt%.

[0011] Furthermore, the pH value of the cleaning composition is 9.5-13.

[0012] The cleaning composition provided by this invention is used to remove cerium oxide nanoparticles adhering to the surface of silicon oxide wafers. This cleaning composition comprises a complexing agent, an organic amine compound, and a pH adjuster, and is preferably an alkaline solution. The addition of the complexing agent allows it to form complex bonds with cerium oxide, inhibiting the binding of cerium oxide to the silicon oxide surface. It also reverses the positive charge of the cerium oxide particles, resulting in a strong repulsive effect between the cerium oxide particles and the wafer surface under alkaline conditions. The addition of the organic amine compound enhances the cleaning solution's ability to remove cerium oxide particles. This cleaning solution does not damage the silicon oxide surface. Attached Figure Description

[0013] Figure 1 shows the surface condition of an uncleaned, contaminated silicon oxide wafer under a scanning electron microscope.

[0014] Figure 2 shows the surface condition of silicon oxide wafers after cleaning with the respective comparative cleaning solutions under a scanning electron microscope.

[0015] Figure 3 shows the surface condition of the silicon oxide wafers after cleaning with the cleaning solution in each embodiment under a scanning electron microscope; Detailed Implementation

[0016] The cleaning composition 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.

[0017] According to the proportions of each component in Table 1, each component was dissolved in deionized water, and the mass percentage was brought up to 100% with deionized water. The pH was adjusted to the corresponding values ​​with KOH to obtain the cleaning solutions of the comparative examples and embodiments of the present invention. All reagents of the present invention are commercially available.

[0018] The method for evaluating the cleaning efficiency of the cleaning solution in the comparative examples and embodiments of this invention:

[0019] 1) Cut the wafer into 2.5cm*3.5cm wafer samples, clean the sample surface with ethanol solution, and then blow dry.

[0020] 2) A contamination experiment was conducted on the surface of the wafer sample using 0.5 wt% cerium oxide polishing slurry with known particle size (the wafer sample was immersed in cerium oxide polishing slurry for 5 min and then taken out and rinsed with water to remove unadsorbed cerium oxide particles) to obtain the sample to be cleaned.

[0021] 3) The surface of the crystal sample to be cleaned was characterized using a scanning electron microscope (SEM) to obtain the contamination status of the wafer surface before cleaning.

[0022] 4) Immerse the wafer sample to be cleaned in the cleaning solution and sonicate for 5 minutes to conduct the cleaning experiment. After sonication, remove the wafer sample, rinse it with water, and then dry it.

[0023] 5) The surface of the cleaned crystal sample was characterized using a scanning electron microscope (SEM) to obtain information on particle removal on the surface of the wafer after cleaning.

[0024] Table 1. Components and content of cleaning solutions in comparative and example samples.

[0025] Figure 1 shows the surface condition of an uncleaned silicon oxide wafer after being contaminated with cerium oxide polishing slurry, as observed under a scanning electron microscope. It can be seen that a large number of cerium oxide particles are attached to the surface of the uncleaned silicon oxide wafer.

[0026] Comparative Example 1 cleaning solution contained only ethanolamine, while Comparative Examples 2 and 3 cleaning solutions contained only complexing agents. As shown in Figure 2, after cleaning, Comparative Examples 1-3 could remove particles adhering to the surface of silicon oxide wafers to a certain extent, but the cleaning effect was not ideal, and a large number of particles remained, with the number of particles >30 at the same magnification.

[0027] The cleaning solutions in Examples 1-11 contained different types and amounts of complexing agents, as well as organic amine compounds, and the pH was adjusted to alkaline (10.5-11) with potassium hydroxide. Examples 1, 10, and 11 used different complexing agents in combination, while Examples 2-9 used a single complexing agent. As shown in Figure 3, after cleaning with the cleaning solutions from the examples, the number of particles adhering to the silicon oxide wafer surface was significantly reduced, with the number of particles less than 3 under a scanning electron microscope. In summary, using an alkaline cleaning solution containing complexing agents and organic amine compounds can effectively remove particle adhesion on silicon oxide wafers.

[0028] Comparative Examples 4, 5, and 6 also contained complexing agents and organic amine compounds in their cleaning solutions, and the pH was adjusted to alkaline 10.5 with potassium hydroxide. Comparing Comparative Examples 4 and 5 with Examples 6 and 7, it can be seen that the cleaning effect of the cleaning solution is poor when the complexing agent content is low (0.05%). This may be because the low complexing agent content cannot effectively complex and reverse the particle charge, resulting in the particles still adhering to the wafer surface and being unable to be removed. Increasing the complexing agent content to 0.066% significantly improves the cleaning effect. However, when the complexing agent content is further increased to 1.5%, the cleaning effect also decreases significantly due to the excessive complexing agent content. Therefore, the preferred concentration of the complexing agent is 0.066%-1.0%. Comparing Comparative Example 6 with Examples 6 and 8, it can be seen that the cleaning effect of the cleaning solution is poor when the ethanolamine concentration is low (0.1%). Further increasing the ethanolamine concentration to 0.2%-5% significantly improves the cleaning effect of the cleaning solution. Meanwhile, comparing Comparative Example 1 with Example 8 further demonstrates that the cleaning solution containing both a complexing agent and an organic amine has a better cleaning effect. Increasing the ethanolamine content (5%) would further increase the cost of the cleaning solution and relatively reduce its commercial value; therefore, further increasing the ethanolamine content is not considered. In summary, the preferred concentration of the organic amine compound is 0.2%-5%.

[0029] To investigate the effects of different pH adjusters, pH values, and different types of organic amine compounds on the cleaning effect of the cleaning solution, each component was dissolved in deionized water according to the proportions in Table 2. The mass percentage was then made up to 100% with deionized water, and the pH was adjusted to the corresponding values ​​using potassium hydroxide, tetramethylammonium hydroxide, or choline hydroxide, thus obtaining the cleaning solutions for the comparative examples and embodiments of this invention.

[0030] Table 2 Comparative examples and components and content of cleaning solutions at different pH values

[0031] Comparative Example 7 contained the complexing agent 2-phosphonobutane-1,2,4-tricarboxylic acid and the organic amine diethylene glycolamine, with a pH of 6.0. Compared to the unwashed sample, this cleaning solution could remove some of the adhered particles to a certain extent, but the cleaning effect was not ideal, and a large number of particles remained on the wafer surface (as shown in Figure 2). When the pH was adjusted to 10.5 or 13 with potassium hydroxide, the cleaning solution showed good cleaning effect (Figure 3, Examples 16 and 17), with <3 particles at the same magnification under a scanning electron microscope. This indicates that the alkaline cleaning solution has a better cleaning effect; under alkaline conditions, cerium oxide particles can form a strong repulsive effect on the wafer surface and are easily removed. Comparative Example 8 contained the complexing agent 2-phosphonobutane-1,2,4-tricarboxylic acid and the organic amine ethanolamine, with a pH of 9.0; however, a large number of particles still remained on the wafer surface after cleaning with this solution. When the pH is adjusted to 9.5 or 10.5 using choline hydroxide, potassium hydroxide, or tetramethylammonium hydroxide, the cleaning effect of the cleaning solution is significantly improved (Figure 3, Examples 12-15). In summary, the preferred pH of the cleaning solution is 9.5-13.

[0032] This invention provides a cleaning composition for removing cerium oxide nanoparticles adhering to the surface of a silicon oxide wafer. The cleaning composition comprises a complexing agent, an organic amine compound, and a pH adjuster, preferably an alkaline solution. The addition of the complexing agent allows it to form complex bonds with cerium oxide, inhibiting the binding of cerium oxide to the silicon oxide surface. It also reverses the positive charge of the cerium oxide particles, resulting in a strong repulsion between the cerium oxide particles and the wafer surface under alkaline conditions. The addition of the organic amine compound enhances the cleaning solution's ability to remove cerium oxide particles. This cleaning solution does not damage the silicon oxide surface.

[0033] 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 composition characterized in that, include: Complexing agents, organic amine compounds, and pH adjusters.

2. The cleaning composition of claim 1, wherein, The complexing agent includes one or more of the following: hydroxyethylidene diphosphonic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, aminotrimethylenephosphonic acid, ethylenediaminetetraacetic acid, polyacrylic acid, and dipotassium hydrogen phosphate.

3. The chemical mechanical polishing liquid according to claim 1, wherein The organic amine compounds include: ethanolamine and diethylene glycolamine.

4. The chemical mechanical polishing liquid according to claim 1, wherein The pH adjuster includes: KOH, tetrabutylammonium hydroxide, or choline hydroxide.

5. The chemical mechanical polishing liquid according to claim 2, wherein The concentration range of the complexing agent is 0.066wt%-1wt%.

6. The chemical mechanical polishing liquid according to claim 3, wherein The concentration range of the organic amine is 0.2 wt% to 5 wt%.

7. The chemical mechanical polishing liquid according to claim 1, wherein The pH value of the cleaning composition is 9.5-13.

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