Chemical mechanical polishing solution for improving TEOS polishing rate, and use thereof

Abstract

Provided in the present invention is a chemical mechanical polishing solution for improving the TEOS polishing rate. The chemical mechanical polishing solution comprises a nitrogen-containing heterocyclic conjugated compound, and cerium oxide particles having negative charges (Zeta ≤ 30 mV). By using the described technical solution, the chemical mechanical polishing solution can significantly improve the TEOS polishing rate, and in addition, can achieve the effects of simplifying the cleaning process after polishing, improving the product yield and productivity, and reducing the production costs.

Description

A chemical mechanical polishing liquid for improving TEOS polishing rate and its application Technical Field

[0001] The present invention relates to the field of chemical mechanical polishing, in particular to a chemical mechanical polishing liquid and application thereof. Background Art

[0002] For the iterative development of DRAM and 3D-NAND, it is necessary to remove a relatively thick layer of silicon oxide. Therefore, there is an urgent need in this field for a cerium oxide polishing solution that can greatly promote the polishing rate of silicon oxide. At the same time, the traditional chemical mechanical polishing solution using negatively charged cerium oxide often faces the technical problem of slow TEOS polishing rate. Therefore, in most cases, cerium oxide particles with positive surface charges are used to polish silicon oxide. However, there are many problems with the chemical mechanical polishing solution using positively charged cerium oxide, such as high defect rate, large amount of residual particles, and difficulty in cleaning.

[0003] Therefore, how to develop a chemical mechanical polishing solution with negatively charged cerium oxide particles on the surface to achieve a polishing rate equivalent to that of positively charged TEOS, while simplifying the cleaning process and improving the yield, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] In order to overcome the above technical defects, the object of the present invention is to provide a chemical mechanical polishing liquid for improving the TEOS polishing rate and its use.

[0005] Specifically, the present invention discloses a chemical mechanical polishing liquid for improving the polishing rate of TEOS, comprising: a nitrogen-containing heterocyclic conjugated compound and cerium oxide particles with negative charges on the surface.

[0006] Preferably, the nitrogen-containing heterocyclic conjugated compound is selected from one or more of 2-pyridinecarboxylic acid, 1,2,4-triazole, 1-methyl-5-mercapto-1H-tetrazole, 5-methyltetrazole, 4-amino-1,2,4-triazole, 3-amino-1,2,4-triazole and cyanuric acid.

[0007] Preferably, the mass percentage concentration of the nitrogen-containing heterocyclic compound is 200ppm-2000ppm.

[0008] Preferably, the Zeta potential of the negatively charged cerium oxide particles is less than -30 mV.

[0009] Preferably, the cerium oxide particles with negative surface charges comprise sol-type cerium oxide particles.

[0010] Preferably, the concentration of the cerium oxide particles with negative charges on the surface is 0.1 wt%-1.0 wt%.

[0011] Preferably, the chemical mechanical polishing solution further comprises a pH regulator, and the pH regulator is selected from KOH or HNO3.

[0012] Preferably, the pH value of the chemical mechanical polishing solution is 9-12.

[0013] The present invention also discloses a use of a chemical mechanical polishing liquid, which is to use any of the above chemical mechanical polishing liquids to improve the polishing rate of TEOS.

[0014] Compared with the prior art, the above technical solution has the following beneficial effects: simplifying the cleaning process after polishing, improving product yield and production rate, and reducing production costs. DETAILED DESCRIPTION

[0015] The advantages of the present invention are further described below with reference to specific embodiments.

[0016] Polishing rate detection method of the chemical mechanical polishing solution in the comparative examples and embodiments of the present invention:

[0017] Polishing tests were conducted on TEOS and Si blank wafers using a Mirra polisher. The polishing conditions included an IC1010 polishing pad, wafer and cerium oxide particle rotation speeds of 93 rpm and 87 rpm, respectively, a pressure of 3 psi, and a polishing fluid flow rate of 150 mL / min. TEOS film thickness was measured using a NanoSpec film thickness measurement system (NanoSpec 6100-300, Shanghai Nano-Tech Co., Ltd.). Blank film thickness was measured at 49 points equally spaced along the diameter, starting at 3 mm from the wafer edge. The polishing rate was the average of these 49 points. Si removal was determined gravimetrically. Si wafers were weighed before and after polishing using an analytical balance with an accuracy of 0.0002 g. The total weight loss was divided by the wafer area and Si density to calculate the average thickness removed. This was then divided by the polishing time to calculate the polishing rate.

[0018] The Zeta potential of the cerium oxide particle surface is measured as follows:

[0019] The surface charge of cerium oxide particles is characterized by zeta potential. The chemical mechanical polishing solution is diluted to a cerium oxide content of 0.2% and then placed in a quartz cuvette. Zeta potential is measured using a Malvern instrument.

[0020] Effect embodiment 1:

[0021] A series of nitrogen-containing heterocyclic compounds were tested in a polishing solution containing 0.5 wt% cerium oxide particles (referred to as Type-1). Type-1 cerium oxide particles are negatively charged, sol-type cerium oxide particles with a surface zeta potential of less than -30 mV. According to the component ratios listed in Table 1, each component was dissolved in deionized water, the pH was adjusted to 12 with KOH, and the weight percentage was made up to 100% with deionized water to obtain the chemical mechanical polishing solutions of Comparative Example 1 and Examples 1-7 of the present invention. The polishing data measured according to the above test method are shown in Table 1.

[0022] Table 1 Components and their contents, polishing test results in Examples 1-7 and Comparative Example 1

[0023] Based on the polishing data of different nitrogen-containing heterocyclic compounds listed in Table 1 and the comparative examples without nitrogen-containing heterocyclic compounds, it can be seen that compared with the comparative example 1 without the addition of nitrogen-containing heterocyclic compounds, the polishing liquids with the addition of nitrogen-containing heterocyclic compounds (Examples 1-7) can all increase the polishing rate of TEOS, among which Examples 2-7 have a more obvious improvement effect on TEOS.

[0024] Effect embodiment 2:

[0025] The effect of nitrogen-containing heterocyclic compounds on the polishing rate of TEOS was further investigated. Different concentrations of nitrogen-containing heterocyclic compounds, TAZ (1,2,4-triazole), were added to Comparative Example 1 (0.5% type-1 negatively charged sol-type cerium oxide particles, pH 12). According to the component ratios in Table 2, each component was dissolved in deionized water, the pH was adjusted to 12 with KOH, and the mass percentage was supplemented with deionized water to 100%, thereby obtaining the chemical mechanical polishing solutions of Comparative Example 1 and Examples 8-12 of the present invention. The polishing data measured according to the above test method are shown in Table 2.

[0026] Table 2 Components, contents and polishing test results of Examples 8-12 and Comparative Example 1

[0027] The data shown in Table 2 show that when the TAZ content is within the range of 200ppm to 1000ppm (Examples 8-10), the TEOS polishing rate of the polishing liquid increases with the increase of TAZ content, and there is a clear linear relationship between the two. When the TAZ concentration reaches 1000ppm (Example 10), and further increasing the content to 1500 or 2000ppm (Example 12), the chemical mechanical polishing liquid reaches a maximum value for improving the TEOS polishing rate, and as the TAZ concentration increases, the promoting effect on the TEOS polishing rate is no longer significant. It should also be pointed out that, referring to Example 8, when only 200ppm of TAZ is added, the TEOS polishing rate of the polishing liquid can be improved by 12%, which shows that TAZ has a significant effect on improving the TEOS polishing rate of the polishing liquid.

[0028] Effect Example 3

[0029] The pH range required for TAZ to improve the TEOS polishing rate was further determined. 0.1% TAZ was added to a negatively charged cerium oxide dispersion, and the pH was adjusted to 11, 10, 9, and 8 using potassium hydroxide or nitric acid. Deionized water was then added to the pH to 100% by weight to produce chemical mechanical polishing solutions for the comparative examples and examples. If the pH was further lowered below 7, the stability of the polishing colloid would be compromised, and the cerium oxide particles would aggregate and precipitate. The corresponding polishing results are shown in Table 3.

[0030] Table 3 Components, contents and polishing test results of Examples 10, 13-15 and Comparative Examples 1-2

[0031] Based on the data in Table 3, it can be seen that when the pH value of the polishing liquid is 8, TAZ has no effect on the polishing rate of TEOS, and is even worse than that of Comparative Example 2 without TAZ. Therefore, when the pH value of the chemical mechanical polishing liquid is between 9 and 12, TAZ has a significant effect on the polishing rate of TEOS.

[0032] Effect Example 4

[0033] The effect of TAZ on TEOS rate in cerium oxide dispersions of varying concentrations was further verified. According to the component ratios listed in Table 4, each component was dissolved in deionized water, the pH was adjusted to 12 with KOH, and the weight percentage was made up to 100% with deionized water. These chemical mechanical polishing solutions of Comparative Examples 1, 3-4, and Examples 10, 16-17 of the present invention were obtained. Polishing data measured using the above test method is shown in Table 4.

[0034] Table 4 Components, contents and polishing test results of Comparative Examples 1, 3-4 and Examples 10, 16-17

[0035] According to the results in Table 4, it can be seen that adding TAZ to the polishing solution with cerium oxide concentrations of 0.1%, 0.5%, and 1% can effectively improve the polishing rate of TEOS.

[0036] It should be noted that the embodiments of the present invention have better practicability and do not impose any form of limitation on the present invention. Any technician familiar with the field may use the technical content disclosed above to change or modify it into an equivalent effective embodiment. However, any modification 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 are still within the scope of the technical solution of the present invention.

Claims

1. A chemical mechanical polishing liquid for improving the polishing rate of TEOS, characterized in that: include: Nitrogen-containing heterocyclic conjugated compounds and cerium oxide particles with negative charges on the surface.

2. The chemical mechanical polishing solution according to claim 1, characterized in that: The nitrogen-containing heterocyclic conjugated compound is selected from one or more of 2-pyridinecarboxylic acid, 1,2,4-triazole, 1-methyl-5-mercapto-1H-tetrazole, 5-methyltetrazole, 4-amino-1,2,4-triazole, 3-amino-1,2,4-triazole and cyanuric acid.

3. The chemical mechanical polishing solution according to claim 1, characterized in that: The zeta potential of the cerium oxide particles with negative charges on the surface is less than -30 mV.

4. The chemical mechanical polishing solution according to claim 1, characterized in that: The cerium oxide particles having negative charges on the surface include sol-type cerium oxide particles.

5. The chemical mechanical polishing solution according to claim 1, characterized in that: The concentration of the cerium oxide particles with negative charges on the surface is 0.1 wt % to 1.0 wt %.

6. The chemical mechanical polishing solution according to claim 1, characterized in that: The polishing liquid includes a pH adjuster.

7. The chemical mechanical polishing composition according to claim 6, wherein The pH regulator is KOH or HNO3.

8. The chemical mechanical polishing solution according to claim 1, characterized in that: The pH value of the chemical mechanical polishing liquid is 9-12.

9. Use of a chemical mechanical polishing liquid, wherein the chemical mechanical polishing liquid according to any one of claims 1 to 8 is used to increase the polishing rate of TEOS.

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