Preparation method for metal-ion-modified abrasive particles, and chemical mechanical polishing solution

Abstract

The present invention provides a preparation method for metal-ion-modified abrasive particles, comprising: adding abrasive particles, a modified metal salt and alkoxysilane into water to form a mixed solution; adjusting the pH value of the mixed solution; and carrying out a reaction in a temperature range of 10°C to 120°C for 1-16 h to obtain metal-ion-modified abrasive particles, wherein the molar ratio of the abrasive particles to the modified metal salt to alkoxysilane is 1:0.005-0.2:0.02-1. By means of the technical solution, the stability of the abrasive particles is effectively improved.

Description

A method for preparing abrasive particles modified by metal ions and a chemical mechanical polishing liquid Technical Field

[0001] The present invention relates to the field of chemical mechanical polishing, and in particular to a method for preparing abrasive particles modified by metal ions and a chemical mechanical polishing liquid. Background Art

[0002] Modern semiconductor technology has made highly miniaturized devices a reality. Billions of components can be integrated onto a silicon substrate for integrated circuits. These components are interconnected through conductive wires and multilayer interconnects. Techniques such as physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), and electrochemical plating (ECP) are used to deposit these thin layers of material. As layers of material are deposited and removed, the top surface of the wafer becomes uneven. These unevennesses can lead to various product defects, making planarization of the conductive and insulating dielectric layers crucial. Chemical mechanical polishing (CMP), pioneered by IBM in the 1980s, is currently considered the most effective method for global planarization. CMP utilizes chemical, mechanical, or a combination of both. Typically, a wafer is mounted on a polishing head, with its front surface in contact with a polishing pad in a CMP apparatus. Under pressure, the 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 constant flow rate between the wafer and the polishing pad, spreading the slurry evenly across the polishing pad due to centrifugal force.

[0003] Polishing compositions generally consist of abrasive particles ("abrasives"), catalysts, stabilizers, oxidants, pH adjusters, and biocides. The types and amounts of these components vary slightly depending on the polishing material. During the polishing process, the combined effects of chemical reactions induced by the chemicals and mechanical grinding by the abrasives remove a certain thickness of material while achieving global planarization. However, as semiconductor sizes shrink, the requirements for polishing fluids are becoming increasingly stringent, and their composition is correspondingly becoming increasingly complex. Maintaining the stability of abrasives in increasingly harsh chemical environments and reducing their effects such as coagulation are crucial for minimizing scratches, lattice damage, and defects on the wafer surface.

[0004] Developing surface-modified abrasive particles for use in chemical mechanical polishing solutions is one way to solve the above-mentioned problems. For example, U.S. Patent No. 6,372,648 Bl discloses the use of aliphatic hydrocarbons, amines, ethers, cyanamides, aromatic hydrocarbons, etc. to modify the surface of oxide abrasives to reduce their degradation under high pH conditions. At the same time, by utilizing their affinity for different materials, the material removal selectivity is adjusted to help produce excellent surface morphology after polishing. Nowadays, integrated circuit manufacturing is becoming increasingly complex, and higher requirements are placed on polishing solutions. Existing technologies are difficult to adapt to the various requirements of polishing solutions. Therefore, it is of great significance to develop abrasive particles and polishing solutions that are suitable for a wider pH range and have higher stability. Summary of the Invention

[0005] In order to overcome the above technical deficiencies, the present invention aims to provide a method for preparing abrasive particles modified with metal ions, comprising:

[0006] Adding the abrasive particles, modified metal salt, and alkoxysilane into water to form a mixed solution, adjusting the pH value of the mixed solution, and reacting the mixed solution at a temperature range of 10° C. to 120° C. for 1 hour to 16 hours to obtain the abrasive particles modified with metal ions;

[0007] The molar ratio of the abrasive particles, the modified metal salt and the alkoxysilane is 1:0.005-0.2:0.02-1.

[0008] Preferably, the abrasive particles are one or more of silicon dioxide, aluminum oxide, and cerium oxide;

[0009] The metal ions are selected from one or more of Cu, Cr, Mn, Mo, Mg, Fe, Co, Ni, and Cd;

[0010] The metal salt is selected from one or more of chloride, nitrate, acetate, and acetylacetonate;

[0011] The alkoxysilane is one or more selected from tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, propyltrimethoxysilane, tert-butyltrimethoxysilane, triethoxy-p-phenylmethylsilane, and p-tolyltrimethoxysilane;

[0012] The molar ratio of the abrasive particles, the modified metal salt and the alkoxysilane is 1:0.01-0.1:0.01-0.2.

[0013] Preferably, the metal ions are one or more of Mn, Co, Fe, and Ni.

[0014] Preferably, the reaction is carried out at a temperature range of 40° C. to 80° C. for 10 to 12 hours.

[0015] Preferably, the pH value of the mixed solution is 2-11.

[0016] Preferably, the pH value of the mixed solution is 8-10.

[0017] Preferably, the loading amount of the metal ions is 0.5 to 5 wt%.

[0018] Another aspect of the present invention discloses a chemical mechanical polishing liquid comprising: abrasive particles modified with metal ions prepared by any of the above methods for preparing abrasive particles modified with metal ions, a metal cation catalyst, an organic stabilizer, an oxidant, and a pH regulator.

[0019] Preferably, the mass percentage concentration of the abrasive particles modified with metal ions is 0.1% to 23%.

[0020] Preferably, the metal cation catalyst is ferric nitrate nonahydrate.

[0021] Preferably, the mass percentage concentration of the metal cation catalyst is 0.01% to 0.1%.

[0022] Preferably, the organic stabilizer is one or more of phthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, citric acid, and maleic acid.

[0023] Preferably, the organic stabilizer is malonic acid.

[0024] Preferably, the mass percentage concentration of the organic stabilizer is 0.001% to 0.1%.

[0025] Preferably, the oxidant is H2O2, and the pH adjuster is HNO3.

[0026] Preferably, the pH value of the chemical mechanical polishing solution is 2-10.

[0027] The chemical mechanical polishing liquid containing the abrasive particles prepared by the preparation method of the abrasive particles modified by metal ions in the present invention has a good polishing rate and better abrasive particle stability, reducing the risk of sedimentation. The mechanism of enhanced stability of the abrasive particles modified by metal ions is as follows: the metal ions replace the hydroxyl groups on the surface of the abrasive particles, and their larger ionic radius and higher charge (higher charge density) effectively increase the repulsive force between the abrasive particles; at the same time, the risk of interconnection of hydroxyl groups between the abrasive particles is reduced, thereby effectively improving the stability of the chemical mechanical polishing liquid. At the same time, since the metal ions only cover a small surface, the effect on the polishing rate of the abrasive particles at a certain concentration is not obvious. The chemical mechanical polishing liquid of the present invention has abrasive particles with good stability, and its service life is also effectively extended. DETAILED DESCRIPTION

[0028] The advantages of the present invention are further described below with reference to specific embodiments.

[0029] The metal ion modified abrasive particles and the chemical mechanical polishing composition thereof of the present invention are described in detail below through specific examples to provide a better understanding of the present invention, but the following examples do not limit the scope of the present invention.

[0030] Specific Examples and Comparisons: According to the formulations given in Table 1, metal ion salts of corresponding concentrations were added to the abrasive particles and stirred. The pH was then adjusted to the target value. After stirring for 30 minutes, alkoxysilane was added to form a mixed solution. The temperature was slowly raised to the target temperature and the reaction was allowed to proceed for the appropriate time. After the reaction was completed, metal ion-modified abrasive particles were obtained.

[0031] Table 1 Preparation conditions of the method for preparing the abrasive particles modified by metal ions in Examples 1-14 and Comparative Examples 1-4

[0032] To test the stability of the abrasive particles prepared by the above preparation methods, the abrasive particles prepared by the preparation methods of Examples 1-164 and Comparative Examples 1-4 were allowed to stand for a certain period of time, and the particle size of the corresponding abrasive particles was measured. The test results are shown in Table 2.

[0033] Table 2 Stability test results of the abrasive particles obtained in Examples 1-16 and Comparative Examples 1-4

[0034] Based on the data in Table 2, it can be seen that the abrasive particles prepared in Examples 1-16 of the present invention can maintain the stability of the average particle size for a long period of time in the chemical mechanical polishing solution. Based on the data of Examples 1-4, it can be seen that there is no significant difference in the particle size of the abrasive particles as the concentration of metal ions increases. By comparing Comparative Example 1 and Example 2, it is found that the silica particles without any modification quickly grow larger until they precipitate and have poor stability. By comparing Comparative Examples 2, 5-7, it can be seen that abrasive particles of different particle sizes have the effect of improving stability after being modified with metal ions. By comparing Comparative Examples 3, 10-11, it can be seen that abrasive particles have the effect of improving stability after being modified with different metal ions. By comparing Comparative Examples 2, 8-9, it can be seen that abrasive particles have the effect of improving stability after being treated with different alkoxysilanes. By comparing Comparative Examples 1, 12-16, it can be seen that this method has the effect of improving the stability of abrasives over a wide pH range.

[0035] The chemical mechanical polishing performance of the above-mentioned abrasive particles was further tested. As shown in Table 3, the chemical mechanical polishing solutions of Examples 17-20 and Comparative Examples 5-8 of the present invention were prepared. Among them, the abrasive particles of the chemical mechanical polishing solutions of Examples 17-20 are the metal ion-modified abrasive particles obtained by the preparation method in Example 4, and the abrasive particles of the chemical mechanical polishing solutions of Comparative Examples 5-8 are the metal ion-modified abrasive particles obtained by the preparation method in Comparative Example 1. The other components of the chemical mechanical polishing solutions of Examples 17-20 and Comparative Examples 5-8 are: cerium oxide: hydrogen peroxide, concentration of 2.0%; metal cation catalyst: ferric nitrate nonahydrate, concentration of 0.01%; organic stabilizer: malonic acid, concentration of 0.03%; corrosion inhibitor: glycine, concentration of 0.05%, and water as the balance. The pH value of the chemical mechanical polishing solution was adjusted to 2.5 using a pH adjuster.

[0036] Specific polishing conditions:

[0037] The pressure was 4.0 psi, the polishing disc and polishing head speeds were 93 / 87 rpm, the polishing pad was IC1010, the polishing fluid flow rate was 100 ml / min, and the polishing machine was a 12” Reflexion LK.

[0038] The test results are shown in Table 3.

[0039] The test results of Examples 17-20 show that the polishing rates of the polishing solution for tungsten and silicon oxide remain relatively stable after different exposure times using the metal ion-modified abrasive particles. However, the polishing rates for tungsten and silicon oxide in the system without metal ion modification are significantly reduced. This demonstrates that the stability of the abrasive particles significantly influences the polishing performance of the polishing solution.

[0040] It should be understood that the % mentioned in the present invention refers to the mass percentage.

[0041] While the specific embodiments of the present invention have been described in detail above, these are merely exemplary and the present invention is not limited thereto. For those skilled in the art, any equivalent modifications and substitutions to the present invention are also within the scope of the present invention. Therefore, any equivalent changes and modifications made without departing from the spirit and scope of the present invention are intended to be encompassed within the scope of the present invention.

Claims

1. A method for preparing a grinding particle modified by a metal ion, characterized in that, Comprising: Adding the abrasive particles, modified metal salt, and alkoxysilane into water to form a mixed solution, adjusting the pH value of the mixed solution, and reacting within the temperature range of 10°C to 120°C for 1 h to 16 h to obtain the abrasive particles modified by metal ions; The molar ratio of the abrasive particles, modified metal salt, and alkoxysilane is 1:0.005 - 0.2:0.02 - 1.

2. The preparation method of the abrasive particles modified by metal ions according to claim 1, characterized in that, The abrasive particles are one or more of silica, alumina, and cerium oxide; The metal ions are selected from one or more of Cu, Cr, Mn, Mo, Mg, Fe, Co, Ni, and Cd; The metal salt is selected from one or more of chloride salts, nitrate salts, acetate salts, and acetylacetonate salts; The alkoxysilane is selected from one or more of tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, propyltrimethoxysilane, tert-butyltrimethoxysilane, triethoxybenzylsilane, and p-tolyltrimethoxysilane; The molar ratio of the abrasive particles, modified metal salt, and alkoxysilane is 1∶0.01 - 0.1:0.01 - 0.

2.

3. The preparation method of the abrasive particles modified by metal ions according to claim 2, characterized in that, The metal ions are one or more of Mn, Co, Fe, and Ni.

4. The preparation method of the abrasive particles modified by metal ions according to claim 1, characterized in that, Reacting within the temperature range of 40°C to 80°C for 10 h to 12 h.

5. The preparation method of the abrasive particles modified by metal ions according to claim 1, characterized in that, The pH value of the mixed solution is 2 - 11.

6. The preparation method of the abrasive particles modified by metal ions according to claim 5, characterized in that, The pH value of the mixed solution is 8 - 10.

7. The preparation method of the abrasive particles modified by metal ions according to any one of claims 1 - 6, characterized in that, The loading amount of the metal ions is 0.5 - 5 wt%.

8. A chemical mechanical polishing liquid, characterized in that, Comprising: The abrasive particles modified by metal ions prepared by the preparation method of the abrasive particles modified by metal ions according to any one of claims 1 - 7, a metal cation catalyst, an organic stabilizer, an oxidant, and a pH regulator.

9. The chemical mechanical polishing liquid according to claim 8, characterized in that, The mass percentage concentration of the abrasive particles modified by metal ions is 0.1% - 23%.

10. The chemical mechanical polishing liquid according to claim 8, characterized in that, The metal cation catalyst is ferric nitrate nonahydrate.

11. The chemical mechanical polishing liquid according to claim 8, characterized in that, The mass percentage concentration of the metal cation catalyst is 0.01% - 0.1%.

12. The chemical mechanical polishing liquid according to claim 8, characterized in that, The organic stabilizer is one or more of phthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, citric acid, and maleic acid.

13. The chemical mechanical polishing liquid according to claim 12, characterized in that, The organic stabilizer is malonic acid.

14. The chemical mechanical polishing liquid according to claim 8, characterized in that the mass percentage concentration of the organic stabilizer is 0.001% to 0.1%.

15. The chemical mechanical polishing liquid according to claim 8, characterized in that the oxidant is H2O2, and the pH regulator is HNO3.

16. The chemical mechanical polishing liquid according to any one of claims 8-15, characterized in that the pH value of the chemical mechanical polishing liquid is 2-10.

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