Rough polishing liquid and preparation method thereof

Abstract

The invention belongs to the technical field of polishing, and particularly discloses rough polishing liquid and a preparation method thereof. The rough polishing liquid provided by the invention comprises the following components in percentage by mass: 1%-5% of a mixed grinding material, 0.5%-2.5% of an oxidizing agent, 8%-13% of a complexing agent, 0.1%-0.3% of a surfactant, 0.5%-0.6% of a dispersing agent, 0.1%-0.2% of a sterilizing agent and the balance of deionized water, the mixed grinding material is a mixture of silicon dioxide, aluminum oxide and cerium dioxide; the complexing agent is a mixture of citric acid, amino acid and absolute ethyl alcohol. The components of the rough polishing liquid provided by the invention play a synergistic effect, and the rough polishing liquid prepared from the components provided by the invention has the advantages that the removal rate of the rough polishing liquid on a copper film is greatly improved, and the roughness of the surface of the copper film can be obviously reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of polishing, and particularly relates to a coarse polishing liquid and a preparation method thereof. Background Art

[0002] With the development of science and technology, the demand for IC chips is increasing. The characteristic size of semiconductors is getting smaller and smaller with Moore's Law, and is approaching the physical limit. In order to deal with the RC delay problem caused by high-density interconnection under 2D packaging, and at the same time have more functions on a chip of a certain size, researchers have focused on Z-direction packaging - 2.5D / 3D packaging. In 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 process. The development of these technologies is inseparable from the support of packaging stacking and IC bare chip welding (bonding) technology. Compared with traditional 2D packaging, 2.5D / 3D packaging has smaller size and quality, and can integrate multiple process technologies into one packaging system, which can effectively reduce parasitic effects and power consumption, thereby greatly improving chip performance.

[0003] Copper vias are used to connect different wafers. During the production process of copper vias, some metal residues may be left on the surface of the wafer, which can cause electrical short circuits. Therefore, there is a necessary process step in all 2.5D / 3D packages, namely copper via CMP (chemical mechanical planarization); currently, the copper via process in 2.5D / 3D packages mainly includes two types of copper vias, TSV / TGV. However, the current TSV / TGV copper via CMP has the problem of too low copper film rough polishing rate. Therefore, it is of great significance to provide a rough polishing liquid. Summary of the invention

[0004] In view of this, in order to solve the problem that the existing rough polishing liquid has too low polishing rate and high cost, the present invention provides a rough polishing liquid and a preparation method thereof.

[0005] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0006] The first aspect of the present invention provides a rough polishing liquid, comprising the following components in percentage by weight: 1%-5% of mixed abrasive, 0.5%-2.5% of oxidant, 8%-13% of complexing agent, 0.1%-0.3% of surfactant, 0.5%-0.6% of dispersant, 0.1%-0.2% of bactericide, and the balance is 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 acid and anhydrous ethanol.

[0009] Compared with the prior art, the rough polishing liquid provided by the present invention selects a mixture of silicon dioxide, aluminum oxide and cerium dioxide as a mixed abrasive, wherein silicon dioxide is softer than the other two materials and can finely polish the surface of the copper film with a lower pressure; aluminum oxide has a higher hardness than silicon dioxide and can remove larger particles and defects on the surface of the single crystal silicon wafer; cerium dioxide chemically reacts with copper ions on the surface of the copper film to remove copper on the surface of the copper film; in the present invention, silicon dioxide performs surface treatment on the copper film, aluminum oxide roughly polishes large particles or defects on the copper film, cerium dioxide chemically reacts with copper on the surface of the copper film to promote the smoothing of the surface of the copper film, and the interaction between the several abrasives greatly improves the polishing rate of the rough polishing liquid and effectively reduces the roughness of the surface of the copper film; the present invention selects citric acid, A mixture of amino acids and anhydrous ethanol is used as a complexing agent, wherein anhydrous ethanol as a co-solvent can help citric acid and amino acids dissolve in the rough polishing solution, ensuring that citric acid and amino acids are evenly dispersed in the rough polishing solution; both citric acid and amino acids can form complexes with copper compounds on the surface of the copper film, effectively improving the polishing rate while reducing the roughness of the copper film surface; the synergistic effect between the three substances further reduces the roughness of the copper film surface and effectively improves the polishing rate of the rough polishing solution; the oxidant can react with the copper on the surface of the copper film to form a removable copper layer; the surfactant can reduce surface damage such as scratches, corrosion pits and pitting on the surface of the copper film; the addition of dispersants and bactericides can ensure that the rough polishing solution will not agglomerate or deteriorate during long-term storage, thereby improving the polishing effect of the rough polishing solution on the copper film.

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

[0011] Preferably, the particle size of the aluminum oxide is 180nm-300nm.

[0012] Preferably, the particle size of the cerium dioxide is 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 silicon dioxide, aluminum oxide and ceria in the mixed abrasive can further improve the polishing effect of the rough polishing liquid.

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

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

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

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

[0019] The present invention further limits the mass ratio of citric acid, amino acid and anhydrous ethanol in the complexing agent, which is conducive to maximizing the synergistic effect between citric acid, amino acid and anhydrous ethanol, greatly improving the polishing rate of the rough polishing liquid during application, and reducing 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, an anionic surfactant or a 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 monoglyceride or polysorbate.

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

[0026] Preferably, the bactericide is chitosan.

[0027] Preferably, the pH of the rough polishing liquid is 8-10.

[0028] The second aspect of the present invention provides a method for preparing the above-mentioned rough polishing liquid, comprising the following steps:

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

[0030] The preparation method of the rough polishing liquid provided by the invention is simple, and green and environmentally friendly chemical reagents are used in the polishing liquid, and the cost is low, and the removal rate of the copper film can be significantly improved, and the roughness of the copper film can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a SEM image of the mixed abrasive of the rough polishing liquid in Example 1 of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0033] Example 1

[0034] This embodiment provides a rough polishing liquid, comprising the following components in percentage by weight: 1% mixed abrasive, 2.5% potassium periodate, 8% complexing agent, 0.3% benzalkonium chloride, 0.5% guar gum, 0.2% chitosan, and the balance is deionized water, with 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 rough polishing liquid, comprising the following steps:

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

[0040] Example 2

[0041] This embodiment provides a rough polishing liquid, comprising the following components in percentage by weight: 5% mixed abrasive, 0.5% potassium hypochlorite, 13% complexing agent, 0.1% sodium hexadecyl sulfate, 0.6% polyacrylamide, 0.1% chitosan, and the balance is deionized water, with 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 ceria 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 rough polishing liquid, comprising the following steps:

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

[0047] Example 3

[0048] This embodiment provides a rough polishing liquid, comprising the following components in percentage by weight: 3% mixed abrasive, 2% hydrogen peroxide, 10% complexing agent, 0.2% polysorbate, 0.55% polyacrylamide, 0.15% chitosan, and the balance is deionized water, with 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 ceria 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 rough polishing liquid, comprising the following steps:

[0053] The mixed abrasive, hydrogen peroxide, complexing agent, polysorbate, polyacrylamide and chitosan are added into deionized water to obtain a rough polishing solution.

[0054] Comparative Example 1

[0055] This comparative example provides a rough polishing liquid, which is different from Example 1 in that:

[0056] Replace silica with an equal amount of alumina;

[0057] The other ingredients and preparation method are the same as those in Example 1.

[0058] Comparative Example 2

[0059] This comparative example provides a rough polishing liquid, which is different from Example 1 in that:

[0060] Replace the alumina with an equal amount of silica;

[0061] The other ingredients and preparation method are the same as those in Example 1.

[0062] Comparative Example 3

[0063] This comparative example provides a rough polishing liquid, which is different from Example 1 in that:

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

[0065] The other ingredients and preparation method are the same as those in Example 1.

[0066] Comparative Example 4

[0067] This comparative example provides a rough polishing liquid, which is different from Example 1 in that:

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

[0069] The other ingredients and preparation method are the same as those in Example 1.

[0070] Comparative Example 5

[0071] This comparative example provides a rough polishing liquid, which is different from Example 1 in that:

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

[0073] The other ingredients and preparation method are the same as those in Example 1.

[0074] Comparative Example 6

[0075] This comparative example provides a rough polishing liquid, which is different from Example 1 in that:

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

[0077] The other ingredients and preparation method are the same as those in Example 1.

[0078] The copper film on the surface of the silicon wafer was polished using the coarse polishing liquid provided in Examples 1-3 and Comparative Examples 1-6. The polishing conditions were as follows: the polishing machine was Beijing Jingyi Precision 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 liquid flow rate was 300 mL / min, the polishing time was 5 min, and the polishing temperature was below 60°C.

[0079] The surface roughness of silicon wafers was tested after polishing using Park ion microscope.

[0080] Polishing rate: The copper film thickness before and after polishing is measured by the KLA RS200+ measuring machine. The difference is the total amount of removal in 5 minutes. The total amount of removal 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 liquid provided in the embodiment of the present invention can obtain a high removal rate while also obtaining good surface roughness, thereby ensuring that subsequent processes can proceed smoothly. Under the condition of a high removal rate of the rough polishing liquid, it can not only save consumables costs but also increase the time required for the entire chip manufacturing process.

[0086] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A rough polishing liquid, characterized in that: The invention comprises the following components in percentage by weight: 1%-5% of mixed abrasive, 0.5%-2.5% of oxidant, 8%-13% of complexing agent, 0.1%-0.3% of surfactant, 0.5%-0.6% of dispersant, 0.1%-0.2% of bactericide, and the balance is 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 acid and anhydrous ethanol.

2. The rough polishing liquid as claimed in claim 1, characterized in that The particle size of the silicon dioxide is 50nm-200nm; and / or The particle size of the aluminum oxide is 180nm-300nm; and / or The particle size of the cerium dioxide is 150nm-180nm.

3. The rough polishing liquid as claimed in claim 1, characterized in that The mass ratio of silicon dioxide, aluminum oxide and cerium dioxide in the mixed abrasive is (1-5):(1-5):

1.

4. The rough polishing liquid according to claim 1, characterized in that The oxidant is at least one of hydrogen peroxide, periodate or hypochlorite.

5. The rough polishing liquid as claimed in claim 4, characterized in that The periodate is potassium periodate; and / or The hypochlorite is potassium hypochlorite.

6. The rough polishing liquid according to claim 1, characterized in that The mass ratio of citric acid, amino acid and anhydrous ethanol in the complexing agent is (1-5):(1-3):

1.

7. The rough polishing liquid according to claim 1 or 6, characterized in that The amino acid is at least one of glycine and sarcosine.

8. The rough polishing liquid according to claim 1, characterized in that The surfactant is at least one of a cationic surfactant, an anionic surfactant or a nonionic surfactant; and / or The dispersant is at least one of polyacrylamide and guar gum; and / or The bactericide is chitosan.

9. The rough polishing liquid according to any one of claims 1 to 8, characterized in that The pH of the coarse polishing liquid is 8-10.

10. A method for preparing a rough polishing liquid according to any one of claims 1 to 9, characterized in that: The steps include: The mixed abrasive, oxidant, complexing agent, surfactant, dispersant and bactericide are added into deionized water to obtain a rough polishing solution.

Images