A method for removing large particles from ceria polishing liquid and a ceria polishing liquid

Abstract

This invention provides a method for removing large particles from cerium oxide polishing slurry. The method includes: providing a first-stage filter element and a second-stage filter element connected sequentially end-to-end; providing a cerium oxide polishing slurry stock solution to be filtered; using the first and second filter elements, controlling the flow rate of the cerium oxide polishing slurry stock solution to a first rate, and filtering the cerium oxide polishing slurry stock solution sequentially to obtain a cerium oxide polishing slurry filtrate with large particles removed. The method for removing large particles from cerium oxide polishing slurry provided by this invention significantly reduces the content of large particles in the cerium oxide polishing slurry, avoids filter element clogging, and simultaneously maintains the high removal rate of cerium oxide during chemical mechanical polishing, significantly reducing the risk of scratches during the polishing process.

Description

Technical Field

[0001] This invention relates to the field of chemical mechanical polishing fluids, and more particularly to a method for removing large particles from cerium oxide polishing fluids and a cerium oxide polishing fluid. Background Technology

[0002] In integrated circuit manufacturing, chemical mechanical polishing (CMP) is a key technology used for surface planarization at different stages of the manufacturing process. With the continuous advancement of chip manufacturing processes, the requirements for CMP are becoming increasingly stringent. However, during the CMP process, some defects inevitably occur on the wafer surface, affecting chip performance and reliability. One of the main factors causing polishing defects is the high content of large abrasive particles in the polishing slurry. During polishing, these large abrasive particles are more likely to scratch the wafer surface, leading to a decrease in chip manufacturing yield.

[0003] Therefore, developing a method to remove large particles from cerium oxide polishing slurry, ensuring the slurry passes smoothly through the filter element, thereby efficiently reducing large particles in the cerium oxide polishing slurry and reducing the risk of scratches during the polishing process, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] To overcome the aforementioned technical challenges, the present invention aims to provide a method for removing large particles from cerium oxide polishing slurry and a cerium oxide polishing slurry itself. A two-stage filter element is used, and the flow rate of the raw cerium oxide polishing slurry is controlled to filter the raw cerium oxide polishing slurry, resulting in a cerium oxide polishing slurry filtrate. This significantly reduces the content of large particles in the cerium oxide polishing slurry, avoids filter element clogging, and simultaneously maintains the high removal rate of cerium oxide during chemical mechanical polishing, significantly reducing the risk of scratches during the polishing process.

[0005] This invention discloses a method for removing large particles from cerium oxide polishing slurry, the method comprising:

[0006] Provides the first-stage filter element and the second-stage filter element connected sequentially from end to end, and provides the original cerium oxide polishing solution to be filtered;

[0007] Using the first and second filter elements, the flow rate of the cerium oxide polishing slurry stock solution is controlled at a first rate, and the cerium oxide polishing slurry stock solution is filtered sequentially to obtain a cerium oxide polishing slurry filtrate after removing large particles.

[0008] Optionally, the first-stage filter element has a precision of 0.3 micrometers to 0.5 micrometers.

[0009] Optionally, the second-stage filter element has a precision of 0.1 micrometers to 0.2 micrometers.

[0010] Optionally, during filtration, the flow rate of the cerium oxide polishing slurry stock solution is controlled: the first rate ranges from 1 kg / min to 3 kg / min.

[0011] This invention also discloses a cerium oxide polishing slurry, prepared using any of the methods described above for removing large particles from cerium oxide polishing slurries. It should be understood that the cerium oxide polishing slurry described in this invention refers only to a cerium oxide particle polishing slurry, and not a complete polishing slurry that can be directly used in chemical mechanical polishing processes after preparing all chemical mechanical polishing slurries.

[0012] The following technical effects can be achieved by adopting the above technical solution:

[0013] 1. It significantly reduces the content of large particles in cerium oxide polishing slurry, while avoiding filter clogging that is prone to occur during the filtration process.

[0014] 2. Based on the significant reduction of large particle content in the cerium oxide polishing slurry obtained by filtration, and taking into account the high removal rate of cerium oxide during chemical mechanical polishing, while significantly reducing the risk of scratches during the polishing process, it can be applied to chemical mechanical polishing of chips in advanced manufacturing processes. Detailed Implementation

[0015] The advantages of the present invention will be further illustrated below with reference to specific embodiments.

[0016] Examples 1-5 and Comparative Examples 1-6 were conducted according to the filtration process shown in Table 1, and the average particle size of the particles in the cerium oxide polishing slurry was tested using dynamic light scattering. The average particle size of the cerium oxide polishing slurry stock solution used was 155 ± 5 nanometers, and the filtration volume was 100 kg. For the comparative examples with clogged filter cartridges, particle size testing was not performed, and the particle size results are not shown in Table 1.

[0017] Table 1. Filtration processes of Examples 1-5 and Comparative Examples 1-6

[0018]

[0019]

[0020] Based on the results of Examples 1-5 and Comparative Examples 1-2, it is evident that filter element blockage occurs when the flow rate exceeds 3 kg / min during filtration. This is due to the excessively high flow rate of the polishing fluid, resulting in a high particle content passing through the filter element simultaneously, causing blockage, rather than the filter element effectively intercepting large particles. Therefore, the filtration flow rate should be controlled to not exceed 3 kg / min during filtration. For reasons of production efficiency and economic benefits, a flow rate below 1 kg / min is also not advisable.

[0021] According to the results of Example 1 and Comparative Example 3, if the accuracy of the secondary filter element is less than 0.1, the effective particles in the polishing fluid will also clog the filter element, making it impossible to effectively intercept large particles.

[0022] As shown in Example 1 and Comparative Example 4, filter clogging occurs when the first-stage filter element's precision is greater than 0.5 micrometers. This is because insufficient precision in the first-stage filter element results in inadequate interception efficiency for large particles in the polishing fluid. Consequently, this causes significant pressure on the second-stage filter element to intercept large particles, ultimately leading to filter clogging and the inability to continue filtration.

[0023] As can be seen from Example 1 and Comparative Example 7, using a single high-precision filter element can also cause filter element clogging.

[0024] Therefore, using a dual-filter system can effectively intercept large particles of different sizes in cerium oxide polishing slurry in stages and extend the service life of the filter cartridges.

[0025] To characterize the change in the content of large particles in the above-mentioned cerium oxide polishing slurry after filtration, a large particle counter was used to test the number of large particles in Examples 1, 2 and Comparative Example 6 with effective filtration. The solid content was 1.0%. The specific test results are as follows:

[0026] Table 1. Large particle test results of cerium oxide polishing slurry stock solution and Examples 1-2 and Comparative Example 6

[0027] Based on the results of Examples 1 and 2 and Comparative Example 6 above, it can be seen that compared with the filtration system using a single filter cartridge, the number of large particles in the cerium oxide polishing liquid filtered by the dual-filter cartridge system is significantly reduced, and the filtration process is highly efficient and stable, which also helps to extend the service life of the filter cartridge. Moreover, within the filtration rate range of 1-3 kg / min, the number of large particles is not further reduced when the filtration speed is slowed down. Therefore, in order to improve filtration efficiency, a filtration method with a high rate should be selected as much as possible.

[0028] To characterize the polishing performance of the aforementioned cerium oxide polishing slurry, its SiO2 removal rate and scratch condition were measured. Specific test conditions are as follows:

[0029] The above-mentioned cerium oxide polishing solution was prepared with a solid content of 0.25 wt% and a pH of 5.5. Its polishing removal rate (RR) on SiO2 wafers and its scratch detection were tested.

[0030] The specific polishing conditions were as follows: the polishing machine was a Mirra, the polishing pad was an IC1010, the Platten and Carrier speeds were 93 rpm and 87 rpm respectively, the pressures were 2.0, 3.0 and 4.0 psi, the polishing fluid flow rate was 150 mL / min, and the polishing time was 60 seconds. The measured polishing rates are recorded in Table 3.

[0031] Table 3 Polishing test results of cerium oxide polishing slurry stock solution and Examples 1-2 and Comparative Example 6

[0032]

[0033] The experimental results show that the cerium oxide polishing solution of the present invention does not reduce its SiO2 removal rate after removing large particles. Moreover, compared with the single-stage filter element of Comparative Example 6, the cerium oxide polishing solution after removing large particles significantly improves the scratching effect on the wafer surface.

[0034] Specifically, comparing the experimental results of Example 1 and Comparative Example 6, it can be seen that using a dual-filter system to filter cerium oxide polishing slurry can effectively reduce its large particle content, extend the service life of the filter element, and reduce the probability of causing scratches on the wafer surface during polishing.

[0035] Therefore, cerium oxide polishing slurries treated using this method can be applied to chemical mechanical polishing of chips in advanced manufacturing processes. It is important to note that when using this method, the filter cartridge precision should be adjusted according to the particle size of the abrasive in the polishing slurry.

[0036] In summary, the method for removing large particles from cerium oxide provided by this invention significantly reduces the content of large particles in the cerium oxide polishing slurry while avoiding filter clogging that is prone to occur during the filtration process. Furthermore, while significantly reducing the content of large particles in the filtered cerium oxide polishing slurry, it also maintains a high removal rate of cerium oxide during chemical mechanical polishing (CMP) and significantly reduces the risk of scratches during the polishing process. This method can be applied to CMP of chips in advanced manufacturing processes.

[0037] 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 method for removing large particles from cerium oxide polishing slurry, characterized in that, The method includes: Provides the first-stage filter element and the second-stage filter element connected sequentially from end to end, and provides the original cerium oxide polishing solution to be filtered; Using the first and second filter elements, the flow rate of the cerium oxide polishing slurry stock solution is controlled at a first rate, and the cerium oxide polishing slurry stock solution is filtered sequentially to obtain a cerium oxide polishing slurry filtrate after removing large particles.

2. The method for removing large particles from cerium oxide polishing slurry as described in claim 1, characterized in that, The first-stage filter element has a precision of 0.3 micrometers to 0.5 micrometers.

3. The method for removing large particles from cerium oxide polishing slurry as described in claim 2, characterized in that, The second-stage filter element has a precision of 0.1 micrometers to 0.2 micrometers.

4. The method for removing large particles from cerium oxide polishing slurry as described in claim 3, characterized in that, During filtration, the flow rate of the cerium oxide polishing slurry stock solution is controlled: the first rate ranges from 1 kg / min to 3 kg / min.

5. A cerium oxide polishing slurry, characterized in that, It is prepared using the method for removing large particles from cerium oxide polishing slurry as described in any one of claims 1-4.

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