A rough polishing liquid and a method for preparing the same

Abstract

This invention belongs to the field of polishing technology, specifically disclosing a coarse polishing solution and its preparation method. The coarse polishing solution provided by this invention comprises the following components by mass percentage: 1%-5% mixed abrasive, 0.5%-2.5% oxidant, 8%-13% complexing agent, 0.1%-0.3% surfactant, 0.5%-0.6% dispersant, 0.1%-0.2% bactericide, and the balance being deionized water; the mixed abrasive is a mixture of silica, alumina, and cerium dioxide; the complexing agent is a mixture of citric acid, amino acids, and anhydrous ethanol. The components of the coarse polishing solution provided by this invention have a synergistic effect. The coarse polishing solution prepared using the components provided by this invention greatly improves the removal rate of copper film and significantly reduces the surface roughness of the copper film.

Description

Technical Field

[0001] This invention belongs to the field of polishing technology, and specifically relates to a coarse polishing liquid and its preparation method. Background Technology

[0002] With the development of technology, the demand for IC chips is increasing, and the feature size of semiconductors is shrinking rapidly due to Moore's Law, approaching its physical limits. To address the RC delay problem caused by high-density interconnects in 2D packaging, and to achieve more functionality on a chip of a given size, researchers have focused on Z-axis packaging—2.5D / 3D packaging. Over the past two decades, the development of 2.5D / 3D packaging technology has mainly gone through three stages: wire bonding, flip chip, and through-hole technology. The development of these technologies relies heavily on packaging stacking and IC bare-chip bonding techniques. Compared to traditional 2D packaging, 2.5D / 3D packaging offers smaller size and weight, and can integrate multiple process technologies into a single packaging system. This effectively reduces parasitic effects and power consumption, thereby significantly improving chip performance.

[0003] Copper vias serve to connect different wafers. During the fabrication of copper vias, some metal residues may be left on the wafer surface, which can cause electrical short circuits. Therefore, a necessary process step in all 2.5D / 3D packaging is copper via CMP (Chemical Mechanical Planarization). Currently, copper via processes in 2.5D / 3D packaging mainly include TSV and TGV copper vias. However, current TSV / TGV copper via CMP suffers from the problem of excessively low copper film rough polishing rate. Therefore, providing a rough polishing solution is of great significance. Summary of the Invention

[0004] In view of this, and in view of the problems of low polishing rate and high cost of existing coarse polishing solutions, the present invention provides a coarse polishing solution and its preparation method.

[0005] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0006] The first aspect of the present invention provides a coarse polishing fluid comprising the following components in weight percentage: 1%-5% mixed abrasive, 0.5%-2.5% oxidant, 8%-13% complexing agent, 0.1%-0.3% surfactant, 0.5%-0.6% dispersant, 0.1%-0.2% bactericide, and the balance being deionized water;

[0007] The mixed abrasive is a mixture of silicon dioxide, aluminum oxide, and cerium dioxide;

[0008] The complexing agent is a mixture of citric acid, amino acids, and anhydrous ethanol.

[0009] Compared to existing technologies, the coarse polishing solution provided by this invention uses a mixture of silicon dioxide, alumina, and cerium dioxide as the mixed abrasive. Silicon dioxide is softer than the other two materials, enabling fine polishing of the copper film surface with lower pressure; alumina is harder than silicon dioxide, removing larger particles and defects from the surface of the single-crystal silicon wafer; cerium dioxide removes copper from the copper film surface through a chemical reaction with copper ions. In this invention, silicon dioxide performs surface treatment on the copper film, alumina performs rough polishing of large particles or defects, and cerium dioxide promotes surface smoothing of the copper film through a chemical reaction with the copper. The interaction between these abrasives greatly improves the polishing rate of the coarse polishing solution and effectively reduces the roughness of the copper film surface. This invention selects citric acid, ... A mixture of amino acids and anhydrous ethanol is used as a complexing agent. Anhydrous ethanol acts as a co-solvent, helping citric acid and amino acids dissolve in the coarse polishing solution and ensuring their uniform dispersion. Both citric acid and amino acids can form complexes with copper compounds on the copper film surface, effectively increasing the polishing rate and reducing the surface roughness of the copper film. The synergistic effect of these three substances further reduces the surface roughness of the copper film and effectively increases the polishing rate of the coarse polishing solution. The oxidant reacts with the copper on the copper film surface to form a removable copper layer. The surfactant reduces surface damage such as scratches, pits, and corrosion on the copper film surface. The addition of dispersants and bactericides ensures that the coarse polishing solution will not agglomerate or deteriorate during long-term storage, thereby improving the polishing effect of the coarse polishing solution on the copper film.

[0010] Preferably, the particle size of the silicon dioxide is 50nm-200nm.

[0011] Preferably, the alumina has a particle size of 180nm-300nm.

[0012] Preferably, the cerium dioxide has a particle size of 150nm-180nm.

[0013] Preferably, the mass ratio of silicon dioxide, aluminum oxide and cerium dioxide in the mixed abrasive is (1-5):(1-5):1.

[0014] Preferably, further limiting the particle size and mass ratio of silica, alumina and cerium dioxide in the mixed abrasive can further improve the polishing effect of the coarse polishing fluid.

[0015] Preferably, the oxidant is at least one of hydrogen peroxide, periodate, or hypochlorite.

[0016] More preferably, the periodate is potassium periodate.

[0017] More preferably, the hypochlorite is potassium hypochlorite.

[0018] Preferably, the mass ratio of citric acid, amino acids and anhydrous ethanol in the complexing agent is (1-5):(1-3):1.

[0019] This invention further limits the mass ratio of citric acid, amino acids and anhydrous ethanol in the complexing agent, which is beneficial to maximize the synergistic effect between citric acid, amino acids and anhydrous ethanol, greatly improves the polishing rate of the coarse polishing solution during application and reduces the roughness of the copper film.

[0020] More preferably, the amino acid is at least one of glycine or sarcosine.

[0021] Preferably, the surfactant is at least one of a cationic surfactant, anionic surfactant, or nonionic surfactant.

[0022] Preferably, the cationic surfactant is at least one of benzalkonium chloride or benzalkonium bromide.

[0023] Preferably, the anionic surfactant is at least one of sodium hexadecyl sulfate or sodium octadecyl sulfate.

[0024] Preferably, the nonionic surfactant is at least one of fatty acid monoglycerides or polysorbates.

[0025] Preferably, the dispersant is at least one of polyacrylamide or glucon.

[0026] Preferably, the bactericide is chitosan.

[0027] Preferably, the pH of the coarse polishing solution is 8-10.

[0028] A second aspect of the present invention provides a method for preparing the above-mentioned coarse polishing solution, comprising the following steps:

[0029] The mixed abrasive, oxidant, complexing agent, surfactant, dispersant and bactericide are added to deionized water to obtain a coarse polishing solution.

[0030] The preparation method of the coarse polishing solution provided by this invention is simple, and all the polishing solutions use green and environmentally friendly chemical reagents, which are inexpensive and can significantly improve the removal rate of copper film and reduce the roughness of copper film. Attached Figure Description

[0031] Figure 1 This is a SEM image of the mixed abrasive in the coarse polishing fluid in Embodiment 1 of the present invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0033] Example 1

[0034] This embodiment provides a coarse polishing solution comprising the following components by mass percentage: 1% mixed abrasive, 2.5% potassium periodate, 8% complexing agent, 0.3% benzalkonium chloride, 0.5% guar gum, 0.2% chitosan, with the balance being deionized water, and a pH of 8.

[0035] The mixed abrasive is a mixture of silicon dioxide, aluminum oxide and cerium dioxide in a mass ratio of 5:5:1;

[0036] The particle size of silicon dioxide is 50 nm, the particle size of aluminum oxide is 300 nm, and the particle size of cerium dioxide is 150 nm.

[0037] The complexing agent is a mixture of citric acid, glycine, and anhydrous ethanol in a mass ratio of 5:1:1;

[0038] This embodiment also provides a method for preparing the above-mentioned coarse polishing solution, including the following steps:

[0039] Mixed abrasive, potassium periodate, complexing agent, benzalkonium chloride, guar gum and chitin are added to deionized water to obtain a rough polishing solution.

[0040] Example 2

[0041] This embodiment provides a coarse polishing solution comprising the following components by mass percentage: 5% mixed abrasive, 0.5% potassium hypochlorite, 13% complexing agent, 0.1% sodium hexadecyl sulfate, 0.6% polyacrylamide, 0.1% chitosan, with the balance being deionized water, and a pH of 10.

[0042] The mixed abrasive is a mixture of silicon dioxide, aluminum oxide and cerium dioxide in a mass ratio of 5:5:1;

[0043] The particle size of silicon dioxide is 200 nm, the particle size of aluminum oxide is 180 nm, and the particle size of cerium dioxide is 160 nm.

[0044] The complexing agent is a mixture of citric acid, sarcosine, and anhydrous ethanol in a mass ratio of 1:5:1;

[0045] This embodiment also provides a method for preparing the above-mentioned coarse polishing solution, including the following steps:

[0046] Mixed abrasive, potassium hypochlorite, complexing agent, sodium hexadecyl sulfate, polyacrylamide, and chitosan are added to deionized water to obtain a rough polishing solution.

[0047] Example 3

[0048] This embodiment provides a coarse polishing solution comprising the following components by mass percentage: 3% mixed abrasive, 2% hydrogen peroxide, 10% complexing agent, 0.2% polysorbate, 0.55% polyacrylamide, 0.15% chitosan, with the balance being deionized water, and a pH of 9.

[0049] The mixed abrasive is a mixture of silicon dioxide, aluminum oxide and cerium dioxide in a mass ratio of 3:4:1.

[0050] The particle size of silicon dioxide is 100 nm, the particle size of aluminum oxide is 200 nm, and the particle size of cerium dioxide is 180 nm.

[0051] The complexing agent is a mixture of citric acid, sarcosine, and anhydrous ethanol in a mass ratio of 4:2:1;

[0052] This embodiment also provides a method for preparing the above-mentioned coarse polishing solution, including the following steps:

[0053] Mixed abrasive, hydrogen peroxide, complexing agent, polysorbate, polyacrylamide, and chitosan are added to deionized water to obtain a coarse polishing solution.

[0054] Comparative Example 1

[0055] This comparative example provides a coarse polishing solution, which differs from Example 1 in that:

[0056] Replace silicon dioxide with an equal amount of aluminum oxide;

[0057] The other components and preparation methods are the same as in Example 1.

[0058] Comparative Example 2

[0059] This comparative example provides a coarse polishing solution, which differs from Example 1 in that:

[0060] Replace aluminum oxide with an equal amount of silicon dioxide;

[0061] The other components and preparation methods are the same as in Example 1.

[0062] Comparative Example 3

[0063] This comparative example provides a coarse polishing solution, which differs from Example 1 in that:

[0064] Replace cerium dioxide with an equal amount of silicon dioxide;

[0065] The other components and preparation methods are the same as in Example 1.

[0066] Comparative Example 4

[0067] This comparative example provides a coarse polishing solution, which differs from Example 1 in that:

[0068] Replace citric acid with an equal amount of glycine;

[0069] The other components and preparation methods are the same as in Example 1.

[0070] Comparative Example 5

[0071] This comparative example provides a coarse polishing solution, which differs from Example 1 in that:

[0072] Replace glycine with an equal amount of anhydrous ethanol;

[0073] The other components and preparation methods are the same as in Example 1.

[0074] Comparative Example 6

[0075] This comparative example provides a coarse polishing solution, which differs from Example 1 in that:

[0076] Replace anhydrous ethanol with an equal amount of glycine;

[0077] The other components and preparation methods are the same as in Example 1.

[0078] The copper film on the surface of the silicon wafer was polished using the coarse polishing solutions provided in Examples 1-3 and Comparative Examples 1-6. The polishing conditions were as follows: the polishing machine was Beijing Jingyi Jingwei Horizon-200, the polishing pad was Wanhua Chemical WH6000, the polishing pressure was 5 psi, the polishing disc / polishing head speed was 103 rpm / 97 rpm, the polishing solution flow rate was 300 mL / min, the polishing time was 5 min, and the polishing temperature was below 60℃.

[0079] The surface roughness of the silicon wafer was detected after polishing using a Park atomic ion microscope.

[0080] Polishing rate: The copper film thickness before and after polishing is measured using a KLA RS200+ measuring machine. The difference is the total amount removed in 5 minutes. The total amount removed divided by 5 is the polishing rate.

[0081] The specific test results are shown in Table 1:

[0082] Table 1

[0083]

[0084]

[0085] The rough polishing solution provided in the embodiments of the present invention can achieve a high removal rate while also obtaining a good surface roughness, thereby ensuring that subsequent processes can proceed smoothly. Under the condition of high removal rate of rough polishing solution, not only can consumable costs be saved, but the time required for the entire chip manufacturing process can also be reduced.

[0086] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A rough polishing liquid characterized by comprising: It includes the following components by mass percentage: 1%-5% mixed abrasive, 0.5%-2.5% oxidant, 8%-13% complexing agent, 0.1%-0.3% surfactant, 0.5%-0.6% dispersant, 0.1%-0.2% bactericide, and the balance being deionized water; The mixed abrasive is a mixture of silicon dioxide, aluminum oxide, and cerium dioxide; The complexing agent is a mixture of citric acid, amino acids and anhydrous ethanol; The surfactant is at least one of cationic surfactant, anionic surfactant, or nonionic surfactant; the dispersant is at least one of polyacrylamide or glucon. The cationic surfactant is at least one of benzalkonium chloride or benzalkonium bromide; the anionic surfactant is at least one of sodium hexadecyl sulfate or sodium octadecyl sulfate; and the nonionic surfactant is at least one of fatty acid monoglycerides or polysorbates.

2. The roughening liquid according to claim 1, wherein The silica has a particle size of 50nm-200nm; and / or The alumina has a particle size of 180nm-300nm; and / or The cerium dioxide has a particle size of 150nm-180nm.

3. The roughening liquid according to claim 1, wherein The mass ratio of silicon dioxide, aluminum oxide and cerium dioxide in the mixed abrasive is (1-5):(1-5):

1.

4. The roughening liquid according to claim 1, wherein The oxidant is at least one of hydrogen peroxide, periodate, or hypochlorite.

5. The roughening liquid according to claim 4, wherein The periodate is potassium periodate; and / or The hypochlorite is potassium hypochlorite.

6. The roughening liquid of claim 1, wherein The mass ratio of citric acid, amino acids and anhydrous ethanol in the complexing agent is (1-5):(1-3):

1.

7. The roughening liquid according to claim 1 or 6, wherein The amino acid is at least one of glycine or sarcosine.

8. The roughening liquid of claim 1, wherein The bactericide is chitosan.

9. The roughening liquid of claim 1, wherein The pH of the coarse polishing solution is 8-10.

10. A method of preparing a rough polishing liquid as claimed in any one of claims 1 to 9, characterized in that, Includes the following steps: The mixed abrasive, oxidant, complexing agent, surfactant, dispersant and bactericide are added to deionized water to obtain a coarse polishing solution.

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