Chemical mechanical polishing solution

Abstract

This invention provides a chemical mechanical polishing slurry comprising abrasive particles, a five-membered nitrogen-containing heterocyclic compound, an organic acid, an amino acid, an oxidant, and water. The polishing slurry of this invention exhibits a high cobalt removal rate and a low titanium and silicon oxide insulating layer removal rate, thereby achieving a high cobalt-to-titanium / silicon oxide removal selectivity ratio and a low cobalt metal static corrosion rate, effectively reducing the risk of corrosion of cobalt wafers by the polishing slurry.

Description

Technical Field

[0001] This invention relates to the field of chemical mechanical polishing in semiconductors, and more particularly to a chemical mechanical polishing slurry. Background Technology

[0002] As chip sizes continue to shrink to below 7nm, traditional contact materials such as tungsten (W) and its related compounds are increasingly facing challenges in reducing contact resistance. Cobalt, with its low resistivity, can effectively reduce contact resistance, thereby reducing energy loss during signal transmission and improving chip performance and efficiency. In advanced processes at 7nm and below, chip manufacturing places even more stringent demands on materials. Cobalt is better suited to these high-precision, complex process conditions, exhibits good compatibility with other materials and process steps, and contributes to achieving smaller linewidths, higher integration, and superior performance, making it an ideal replacement for W as the center line (MOL) contact material. Furthermore, as technology nodes shrink to 10nm and below, Cu, as an interconnect material for back-to-line (BEOL) processes, faces challenges such as a sharp increase in resistivity due to electron scattering, size limitations of barrier / wiring layers, and non-conformal deposition of narrow channel widths. Co, due to its excellent conformal deposition capability in high aspect ratio trenches and good compatibility with thinner pads, has become the preferred choice for next-generation interconnects. Chemical mechanical polishing (CMP) is an essential step in the application of Co to achieve surface planarization. When Co is used as a wiring material, its CMP requires a high removal rate (greater than 100 nm / min) and a clean, smooth surface. However, for the highly reactive cobalt metal, finding a polishing slurry that meets the polishing requirements has become a new challenge.

[0003] US11264250B2 discloses a composition for polishing cobalt / cobalt alloy substrates, the composition comprising inorganic particles, anionic surfactants, amino acids, and an oxidizing agent. The composition exhibits a static etching rate (SER) of less than [value missing] for cobalt. US2020308445A1 discloses a method for chemical mechanical polishing of cobalt, using a chemical mechanical polishing composition containing aspartic acid and phosphonic acid with an alkyl group having more than ten carbon atoms, thereby achieving a high cobalt removal rate. And a low cobalt corrosion rate. In 2020, KWON et al. [Study on effect of eomplexing agents on Cooxidation / dissolution for chemical-mechanical polishing and cleaning process[J]. Microelectronic Engineering, 2020, 227: 111308.] compared the effects of three complexing agents, glycine, ethylenediaminetetraacetic acid (EDTA) and citric acid, on the Co removal rate. They found that the stability constant of the cobalt complex with citric acid was the smallest, indicating that its complexing ability was the worst. Moreover, when H2O2 was added, after soaking in a solution containing citric acid for 2 minutes, the surface of Co was completely covered by Co3O4 due to the oxidation rate being much greater than the complexation rate, resulting in over-oxidation and surface deterioration. In 2021, LEI et al. [Effect of benzotriazole and 5-methyl / 1-Hcarboxyl benzotriazole on chemical mechanical polishing of cobalt in H2O2-based slurry[J]. ECS Journal of Solid State Science and Technology, 2021, 10(7): 074002.] compared the corrosion inhibition effects of three azole corrosion inhibitors with different functional groups—benzotriazole (BTA), 5-methylbenzotriazole (TTA), and 1H-benzotriazole carboxylic acid (CBT)—on Co corrosion. The results showed that the oxygen atom in the carboxyl functional group of CBT and the nitrogen atom in the imidazole ring can form a multi-center adsorbed passivation layer with the Co(II) oxide layer, thus resulting in a stronger corrosion inhibition effect.

[0004] Chemical mechanical polishing (CMP) is the only method that can achieve both local and global planarization of Co. Currently, CMP processes for cobalt mainly consist of two steps: Step 1: Cobalt cap removal. A cobalt metal polishing slurry is used to remove a large amount of cobalt at a high material removal rate, and polishing stops at the titanium barrier layer via endpoint detection. Because this step has a very high cobalt removal rate while the titanium removal rate is almost zero, dish-shaped depressions easily form at the cobalt location at the polishing endpoint. Step 2: Barrier layer removal and dish-shaped depression repair. A cobalt barrier layer polishing slurry is used to remove the titanium barrier layer, some dielectric material, and cobalt, repairing the dish-shaped depressions and defects formed in Step 1 to achieve surface planarization. In Step 1, in addition to a high cobalt removal rate, it is also necessary to stop at the Ti barrier layer and the silicon oxide insulating layer. Furthermore, due to the high reactivity of cobalt, the polishing process is prone to pitting corrosion, galvanic corrosion, and other defects, leading to increased resistance and even device malfunction. While currently reported polishing slurries have improved the surface corrosion of Co, it is difficult to simultaneously control the corrosion of the Co surface at high Co removal rates. Therefore, there is an urgent need to develop innovative Co polishing slurries with high and adjustable Co removal rates to improve the selectivity of Co removal rates for the barrier layer Ti and the silicon oxide insulating layer Oxide, while reducing the static corrosion rate of Co and improving the surface quality of Co after polishing. Summary of the Invention

[0005] To overcome the aforementioned technical deficiencies, the present invention aims to provide a chemical mechanical polishing slurry. The proposed slurry, by adding abrasive particles, a five-membered nitrogen-containing heterocyclic compound, organic acid, amino acid, oxidant, and water, can provide a high cobalt removal rate and a low removal rate for the barrier layer Ti and the silicon oxide insulating layer Oxide. This results in a high cobalt / Ti / Oxide removal selectivity ratio, effectively reducing the static corrosion rate of cobalt metal and significantly lowering the risk of corrosion of the cobalt wafer by the polishing slurry.

[0006] This invention discloses a chemical mechanical polishing fluid, comprising abrasive particles, a five-membered nitrogen-containing heterocyclic compound, an organic acid, an amino acid, an oxidant, and water.

[0007] Optionally, the five-membered nitrogen-containing heterocyclic compound is selected from one or more of imidazole, benzotriazole, 1-hydroxy-benzotriazole, 1H-benzotriazole carboxylic acid, methylbenzotriazole, 1,2,4-triazole, 3-methyl-1,2,4-triazole, 3-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 1,2,4-triazole, 1,2,3-triazole, 1-phenyl-5-mercaptotetrazole, 1-methyl-5-mercapto-1H-tetrazole, 5-phenyltetrazole, 5-methyl-1H-tetrazole, 5-amino-1H-tetrazole, 5-mercapto-1H-tetrazole, 5-phenyl-1H-tetrazole, 5-benzyl-1H-tetrazole, and tetrazazole.

[0008] Optionally, the mass percentage concentration of the five-membered nitrogen-containing heterocyclic compound ranges from 0.1% to 1%.

[0009] Optionally, the organic acid is selected from one or more of salicylic acid, 3-methylsalicylic acid, benzoic acid, phthalic acid, p-hydroxybenzoic acid, isophthalic acid, 5-methoxysalicylic acid, 4-hydroxyphthalic acid, 2,3-dihydroxybenzoic acid, 2-pyridinecarboxylic acid, nicotinic acid, 3-methoxy-4-methylbenzoic acid, 2,3,4-trihydroxybenzoic acid, 5-fluoro-2-pyridinecarboxylic acid, 2-fluoroisonicotinic acid, 2-aminopyrimidine-5-carboxylic acid, 2,4,6-trifluorobenzoic acid, and 5-methoxyisophthalic acid.

[0010] Optionally, the mass percentage concentration of the organic acid ranges from 0.01% to 0.5%.

[0011] Optionally, the amino acid is selected from one or two of aspartic acid, glutamic acid, histidine, glycine, alanine, leucine, serine, cysteine, methionine, asparagine, and glutamine.

[0012] Optionally, the total mass percentage concentration of the amino acids is between 0.3% and 1.5%.

[0013] Optionally, the abrasive particles are silicon dioxide particles; the mass percentage concentration of the abrasive particles ranges from 0.1% to 3%; and the particle size ranges from 30 to 120 nm.

[0014] Optionally, the oxidant is hydrogen peroxide; the mass percentage concentration of the oxidant ranges from 0.1% to 1%.

[0015] Optionally, the pH value of the chemical mechanical polishing fluid is 6.0 to 8.0.

[0016] The chemical mechanical polishing slurry of the present invention may also contain additives commonly used in the art, such as pH adjusters and bactericides. The polishing slurry of the present invention can be concentrated and prepared; it can be diluted with deionized water to the concentration range of the present invention and an oxidant can be added before use.

[0017] Compared with existing technologies, the above technical solution has the following advantages:

[0018] 1. It has a high cobalt removal rate and a low Ti and Oxide removal rate, thus having a high cobalt removal rate selectivity relative to Ti / Oxide removal rate.

[0019] 2. It can effectively reduce the static corrosion rate of cobalt metal and effectively reduce the risk of polishing slurry corroding cobalt wafers. Attached Figure Description

[0020] Figure 1 and Figure 2 The images are microscopic images of the ECP Co wafer surface before and after immersion in Comparative Example 1.

[0021] Figure 3 and Figure 4 These are microscope images of the ECP Co wafer surface before and after immersion in Example 1. Detailed Implementation

[0022] The advantages of the present invention are further illustrated below with reference to specific embodiments, but the scope of protection of the invention is not limited to the following embodiments.

[0023] Table 1 shows Examples 1-15 and Comparative Examples 1-3 of the chemical mechanical polishing slurry of the present invention. According to the formulations given in the table, all components except the oxidant are mixed thoroughly in sequence. The pH value is adjusted to the required value using a pH adjuster (such as KOH or HNO3). The oxidant is added and mixed thoroughly before use. The polishing slurry of the present invention can also be pre-prepared as a concentrated sample, diluted with deionized water at a certain ratio, and then the oxidant is added before use. All reagents and raw materials used in the present invention are commercially available. All contents refer to mass percentages.

[0024] Table 1. Examples 1-15 and Comparative Examples 1-3 of Chemical Mechanical Polishing Fluids

[0025]

[0026]

[0027] Using the polishing solutions of Examples 1-15 and Comparative Examples 1-3 of the present invention, electrochemically plated cobalt (ECP Co, with a thickness of [missing information]) was performed under the following conditions. ), titanium (Ti, thickness is ), silicon dioxide (Oxide, thickness is Polishing was performed under the following conditions: a 12” Reflexion LK polishing machine, an IC1000 (or VP9280) polishing pad, a polishing pressure of 2.0 psi, a polishing disc and polishing head rotation speed of 63 / 57 rpm, a polishing slurry flow rate of 300 mL / min, a cobalt polishing time of 30 s, and all other conditions of 1 min. The polishing results are shown in Table 2.

[0028] Polishing solutions 1-15 from Examples 1-15 and 1-3 from Comparative Examples 1-3 were placed in a constant temperature water bath at 50°C. ECP Co wafers were then immersed in the different polishing solutions. After 5 minutes, the wafers were removed and cleaned with DIW (Digital Etching Washer). The subsequent values ​​were measured. Static etching rate = (thickness before immersion - thickness after immersion) / 5. The results are shown in Table 2.

[0029] Meanwhile, optical microscopy was used to study the changes on the wafer surface before and after ECP Co immersion. Figure 1 and Figure 2 Optical microscope images of the ECP-Co wafer before and after immersion in Comparative Example 1 are shown. Figure 3 and Figure 4 Optical microscope images of the ECP Co wafer before and after immersion in Example 1 are shown.

[0030] Table 2. Experimental results of chemical mechanical polishing slurries in Examples 1-15 and Comparative Examples 1-3.

[0031]

[0032] Comparative Examples 1-3 used only one of the five-membered nitrogen-containing heterocyclic compounds and organic acids, resulting in a lower cobalt removal rate and a higher static corrosion rate. Compared to Comparative Examples 2 and 3, Example 14, with the addition of less of the five-membered nitrogen-containing heterocyclic compound and organic acid, significantly improved the cobalt removal rate, reduced the static corrosion rate of Co by the polishing solution, and provided better protection for the Co surface.

[0033] Compared with Comparative Examples 1-3, Examples 1-15 of the present invention, by simultaneously adding a five-membered nitrogen-containing heterocyclic compound and an organic acid inhibitor, as well as a suitable amino acid, can not only obtain a higher cobalt removal rate, but also significantly reduce the static corrosion rate of cobalt and protect the surface of the polished cobalt.

[0034] Figure 1 and Figure 2 The optical microscope images shown depict the surface of the ECP Co wafer before and after immersion in the polishing solution of Comparative Example 1. (Comparison attached) Figure 1 and Figure 2It can be seen that the surface morphology of the ECP Co wafer before and after immersion in the polishing solution of Comparative Example 1 is completely different. After immersion, obvious corrosion marks appear on the surface of the wafer. Comparative Examples 2 and 3 show similar corrosion results.

[0035] Figure 3 and Figure 4 The optical microscope images shown depict the ECP Co wafer surface before and after immersion in the polishing solution of Example 1. Clearly, the surface of the ECP Co wafer is almost identical before and after immersion in the polishing solution of Example 1, and no obvious corrosion was observed on the wafer surface. Examples 2-15 all showed similar corrosion results. These static corrosion results demonstrate that the polishing solution of the present invention can effectively control the risk of corrosion to cobalt wafers.

[0036] Furthermore, as can be seen from the polishing rates and removal selectivity of Comparative Examples 1-3 and Examples 1-15, the polishing slurry of the present invention exhibits a low removal rate for both Ti and Oxide, resulting in a high removal rate selectivity of cobalt relative to Ti / Oxide, which helps to control the polishing endpoint.

[0037] It should be noted that the embodiments of the present invention have better implementability and are not intended to limit the present invention in any way. Any person skilled in the art may use the above-disclosed technical content to change or modify it into equivalent effective embodiments. However, any modifications 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 shall still fall within the scope of the technical solution of the present invention.

Claims

1. A chemical mechanical polishing slurry, characterized in that, It includes abrasive particles, five-membered nitrogen-containing heterocyclic compounds, organic acids, amino acids, oxidants, and water.

2. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The five-membered nitrogen-containing heterocyclic compound is selected from one or more of imidazole, benzotriazole, 1-hydroxy-benzotriazole, 1H-benzotriazole carboxylic acid, methylbenzotriazole, 1,2,4-triazole, 3-methyl-1,2,4-triazole, 3-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 1,2,4-triazole, 1,2,3-triazole, 1-phenyl-5-mercaptotetrazole, 1-methyl-5-mercapto-1H-tetrazole, 5-phenyltetrazole, 5-methyl-1H-tetrazole, 5-amino-1H-tetrazole, 5-mercapto-1H-tetrazole, 5-phenyl-1H-tetrazole, 5-benzyl-1H-tetrazole, and tetrazazole.

3. The chemical mechanical polishing slurry as described in claim 2, characterized in that, The mass percentage concentration of the five-membered nitrogen-containing heterocyclic compound ranges from 0.1% to 1%.

4. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The organic acid is selected from one or more of the following: salicylic acid, 3-methylsalicylic acid, benzoic acid, phthalic acid, p-hydroxybenzoic acid, isophthalic acid, 5-methoxysalicylic acid, 4-hydroxyphthalic acid, 2,3-dihydroxybenzoic acid, 2-pyridinecarboxylic acid, nicotinic acid, 3-methoxy-4-methylbenzoic acid, 2,3,4-trihydroxybenzoic acid, 5-fluoro-2-pyridinecarboxylic acid, 2-fluoroisonicotinic acid, 2-aminopyrimidine-5-carboxylic acid, 2,4,6-trifluorobenzoic acid, and 5-methoxyisophthalic acid.

5. The chemical mechanical polishing slurry as described in claim 4, characterized in that, The organic acid has a mass percentage concentration range of 0.01% to 0.5%.

6. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The amino acid is selected from one or two of the following: aspartic acid, glutamic acid, histidine, glycine, alanine, leucine, serine, cysteine, methionine, asparagine, and glutamine.

7. The chemical mechanical polishing slurry as described in claim 6, characterized in that, The total mass percentage concentration of the amino acids is between 0.3% and 1.5%.

8. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The abrasive particles are silica nanoparticles; the mass percentage concentration of the abrasive particles ranges from 0.1% to 3%; and the particle size ranges from 30 to 120 nm.

9. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The oxidant is hydrogen peroxide; the mass percentage concentration of the oxidant ranges from 0.1% to 1%.

10. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The pH value of the chemical mechanical polishing slurry is 6.0 to 8.0.

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