Chemical mechanical polishing solution for improving TEOS (tetraethyl orthosilicate) polishing rate and application of chemical mechanical polishing solution

Abstract

The invention provides a chemical mechanical polishing solution for improving the polishing rate of TEOS (tetraethyl orthosilicate). The chemical mechanical polishing solution comprises a nitrogen-containing heterocyclic ring conjugated compound, a nitrogen-containing heterocyclic ring conjugated compound and a nitrogen-containing heterocyclic ring conjugated compound, -30 mV) of cerium oxide particles. After the technical scheme is adopted, the chemical mechanical polishing solution can obviously improve the polishing rate of TEOS (tetraethyl orthosilicate), and in addition, the effects of simplifying the cleaning process after polishing, improving the product yield and the yield and reducing the production cost can be achieved.

Description

Technical Field

[0001] The present invention relates to the field of chemical mechanical polishing, and particularly to a chemical mechanical polishing liquid and its use. Background Art

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

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

[0004] In order to overcome the above technical defects, the purpose 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 TEOS polishing rate, comprising: a nitrogen-containing heterocyclic conjugated compound, and cerium oxide particles with a negative charge 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 200 ppm - 2000 ppm.

[0008] Preferably, the Zeta potential of the cerium oxide particles with a negative charge on the surface is less than -30 mV.

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

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

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

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

[0013] The present invention also discloses a use of the chemical mechanical polishing liquid, which is used for improving the polishing rate of TEOS as described in any one of the above.

[0014] After adopting the above technical solution, compared with the prior art, it has the following beneficial effects: simplifying the cleaning process after polishing, improving the product yield and productivity, and reducing the production cost. Detailed Embodiments

[0015] The advantages of the present invention are further elaborated below in conjunction with specific embodiments.

[0016] The method for detecting the polishing rate of the chemical mechanical polishing liquid in the comparative examples and embodiments of the present invention:

[0017] Use a Mirra polishing machine to perform polishing tests on TEOS and Si blank wafers. The corresponding polishing conditions include: an IC1010 polishing pad, the rotation speeds of the wafer and cerium oxide particles are 93 rpm and 87 rpm respectively, the pressure is 3 psi, and the flow rate of the polishing liquid is 150 mL / min. The TEOS film thickness is measured by a NanoSpec film thickness measurement system (NanoSpec6100 - 300, Shanghai Nano Technology Co., Ltd.). For the blank wafer film thickness, starting from 3 mm at the wafer edge, measure 49 points at equal intervals on the diameter line. The polishing rate is the average value of the 49 points. The removal amount of Si is obtained by the weighing method. The Si wafer is weighed using an analytical balance with an accuracy of 0.0002 g before and after polishing. Divide the total weight loss by the wafer area and the Si density to calculate the average removed thickness, and then divide it by the polishing time to calculate the polishing rate.

[0018] The method for measuring the Zeta potential on the surface of cerium oxide particles is as follows:

[0019] The surface charge of cerium oxide particles is characterized by the Zeta potential. Dilute the chemical mechanical polishing liquid to a cerium oxide content of 0.2%, and then place it in a quartz cuvette. The Zeta potential is measured using Malvern instruments.

[0020] Effect Example 1:

[0021] A series of nitrogen-containing heterocyclic compounds were tested in a polishing liquid containing 0.5 wt% cerium oxide particles (referred to as type-1). The type-1 cerium oxide particles are a negatively charged sol-type cerium oxide particle with a surface Zeta potential less than -30 mV. According to the component ratios in Table 1, each component was dissolved in deionized water, the pH was adjusted to 12 with KOH, and the mass percentage was made up to 100% with deionized water to obtain the chemical mechanical polishing liquids 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, and polishing test results in Examples 1-7 and Comparative Example 1

[0023]

[0024]

[0025] Based on the different nitrogen-containing heterocyclic compounds listed in Table 1 and the polishing data of the comparative example without nitrogen-containing heterocycles, it can be seen that compared with Comparative Example 1 without nitrogen-containing heterocyclic compounds, the polishing liquids (Examples 1-7) added with nitrogen-containing heterocyclic compounds can all improve the polishing rate of TEOS, and the improvement effect of Examples 2-7 on TEOS is more obvious.

[0026] Effect Example Two:

[0027] To further explore the influence of nitrogen-containing heterocyclic compounds on the polishing rate of TEOS. Different concentrations of the nitrogen-containing heterocyclic compound TAZ (1,2,4-triazole) were added on the basis of Comparative Example 1 (0.5% type-1 negatively charged sol-type cerium oxide particles, pH value 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 made up to 100% with deionized water to obtain the chemical mechanical polishing liquids 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.

[0028] Table 2 Components, contents and polishing test results of Examples 8-12 and Comparative Example 1

[0029]

[0030] From the data shown in Table 2, within the range of 200 ppm to 1000 ppm of the content of TAZ (Examples 8 - 10), the TEOS polishing rate of the polishing liquid increases with the increase of the content of TAZ, and there is an obvious linear relationship between the two. When the TAZ concentration reaches 1000 ppm (Example 10), and when the content continues to increase to 1500 or 2000 ppm (Example 12), the improvement of the chemical mechanical polishing liquid on the TEOS polishing rate reaches the maximum value, and with the increase of the TAZ concentration, the promoting effect on the TEOS polishing rate is no longer obvious. At the same time, it should also be pointed out that referring to Example 8, when only 200 ppm of TAZ is added, the TEOS polishing rate of the polishing liquid can be increased by 12%. Thus, it can be seen that TAZ has an obvious promoting effect on the TEOS polishing rate of the polishing liquid.

[0031] Effect Example Three

[0032] Further determine the pH range required for TAZ to increase the TEOS polishing rate. Add 0.1% TAZ to the negatively charged cerium oxide dispersion liquid, and use potassium hydroxide or nitric acid to adjust the pH to 11, 10, 9, and 8, and make up the mass percentage to 100% with deionized water to obtain the chemical mechanical polishing liquids of each comparative example and example. If the pH continues to be lowered to below 7, the stability of the polishing colloid will be damaged, and the cerium oxide particles will agglomerate and precipitate. The corresponding polishing results are shown in Table 3.

[0033] Table 3 Components, contents and polishing test results of Example 10, 13 - 15 and Comparative Examples 1 - 2

[0034]

[0035] Based on the data in Table 3, when the pH value of the polishing liquid is 8, TAZ has no promoting effect on the TEOS polishing rate, and it is even worse than Comparative Example 2 without addition. Therefore, when the pH value of the chemical mechanical polishing liquid is in the range of 9 - 12, TAZ has an obvious promoting effect on the TEOS polishing rate.

[0036] Effect Example Four

[0037] Further verify the influence of TAZ on the TEOS rate in cerium oxide dispersion liquids with different concentrations. According to the component ratios in Table 4, dissolve each component in deionized water, adjust the pH to 12 with KOH, and make up the mass percentage to 100% with deionized water to obtain the chemical mechanical polishing liquids of Comparative Examples 1, 3 - 4 and Examples 10, 16 - 17 of the present invention. The polishing data measured according to the above test method are shown in Table 4.

[0038] Table 4 Components, contents and polishing test results of Comparative Examples 1, 3 - 4 and Examples 10, 16 - 17

[0039]

[0040] It can be seen from the results in Table 4 that adding TAZ to the polishing fluids with cerium oxide concentrations of 0.1%, 0.5%, and 1% can effectively improve the polishing rate of TEOS.

[0041] It should be noted that the embodiments of the present invention have good implementability and do not impose any form of limitation on the present invention. Any person skilled in the art may use the disclosed technical content to modify or transform it into equivalent effective embodiments. However, as long as the content does not depart from the technical solution of the present invention, any modification, equivalent change, or modification made to the above embodiments based on the technical essence of the present invention still falls 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, Comprising: A nitrogen-containing heterocyclic conjugated compound and cerium oxide particles with a negative charge on the surface.

2. The chemical mechanical polishing liquid 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 liquid according to claim 1, wherein, The Zeta potential of the cerium oxide particles with a negative charge on the surface is less than -30 mV.

4. The chemical mechanical polishing liquid according to claim 1, wherein The cerium oxide particles with a negative charge on the surface comprise sol-type cerium oxide particles.

5. The chemical mechanical polishing liquid according to claim 1, wherein The concentration of the cerium oxide particles with a negative charge on the surface is 0.1 wt% - 1.0 wt%.

6. The chemical mechanical polishing liquid according to claim 1, wherein The polishing liquid comprises a pH regulator.

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

8. The chemical mechanical polishing liquid 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, the use of the chemical mechanical polishing liquid according to any one of claims 1 - 8 for improving the TEOS polishing rate.

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