TW202124621A - Chemical mechanical polishing slurry - Google Patents

Abstract

The present invention provides a chemical mechanical polishing slurry, including abrasive particles, a catalyst, a stabilizer, a cross-linked macromolecular surface defect inhibitor, an oxidant, water and a pH regulating agent. The chemical mechanical polishing slurry of the present invention can simultaneously polish tungsten, silicon oxide and silicon nitride, it ensures high tungsten polishing speed, as well as having both of a middling silicon oxide polishing speed and a low silicon nitride polishing speed, which can greatly reduce the surface defects existing the surface of the polished silicon nitride and achieve a rapid planarization.

Description

Chemical mechanical polishing liquid

The invention relates to a chemical mechanical polishing liquid.

Modern semiconductor technology is developing rapidly in the direction of miniaturization. Semiconductor integrated circuits include a silicon substrate and millions of components on it, forming an interconnect structure through multi-layer interconnects. Layers and structures include a variety of materials, such as single crystal silicon, silicon dioxide, tungsten, silicon nitride, and various other conductive, semiconductive, and dielectric materials. The thin layer structure of these materials can be manufactured by a variety of deposition techniques, such as physical vapor deposition (PVD), chemical vapor deposition (CVD), and plasma enhanced chemical vapor deposition (PECVD), after which the excess materials need to be removed . As multiple layers of material are deposited and removed, the uppermost surface of the wafer becomes uneven. These unevenness may cause various defects of the product, so the planarization technology of the conductive layer and the insulating dielectric layer becomes particularly important. In the 1980s, the chemical mechanical polishing (CMP) technology pioneered by IBM was considered the most effective method for global planarization.

Chemical mechanical polishing (CMP) is composed of chemical action, mechanical action, and a combination of two actions. Generally, the wafer is fixed on the polishing head and its front surface is in contact with the polishing pad in the CMP equipment. Under a certain pressure, the polishing head moves linearly on the polishing pad or rotates in the same direction as the polishing table. At the same time, a polishing composition ("slurry") is injected between the wafer and the polishing pad at a certain flow rate, and the slurry is spread on the polishing pad due to centrifugal effect. Thus, under the dual action of chemical and mechanical, the surface of the wafer is polished and the entire area is planarized. CMP can be used to remove unwanted surface morphology and surface defects, such as rough surfaces, adsorbed impurities, lattice damage, scratches, etc.

In the design and manufacture of semiconductor integrated circuits, tungsten is used to form interconnects and contact plugs. Chemical mechanical polishing is the preferred method of polishing tungsten. Because tungsten has a certain degree of hardness, its polishing process is somewhat different from other metals. At the same time, in some practical applications of chemical mechanical polishing, tungsten, silicon oxide, and silicon nitride need to be polished at the same time. Due to the need to control the speed, pits, and surface defects of several different media, this poses a challenge to the design of the polishing composition. US Patent US9567491 discloses a polishing composition that can simultaneously polish tungsten, silicon oxide, and silicon nitride. It describes a method for reducing tungsten recesses on a patterned wafer, but it does not propose measures to solve silicon nitride surface defects. The removal rate of tungsten is slower than that of silicon oxide. US Patent US9771496 discloses a polishing composition containing a cyclopolysaccharide compound, which can simultaneously polish tungsten, silicon oxide and silicon nitride. This combination can greatly reduce silicon oxide defects, but it does not help reduce silicon nitride surface defects. Chinese patent CN104284960 discloses a polishing composition for highly selective polishing of silicon oxide/silicon nitride, which can control the defects of silicon nitride, but the combination cannot be used for tungsten polishing. Chinese patent CN105229110 discloses a polishing composition that can control surface defects of silicon nitride, but the combination cannot be used for polishing tungsten. However, if the surface defects of the silicon nitride after polishing are not well controlled, the dielectric layer deposited on it will be uneven, which will affect the wafer yield.

It can be seen that seeking a polishing composition that can simultaneously polish tungsten, silicon oxide, and silicon nitride, and can reduce surface defects of silicon nitride, is of great significance in this field.

In order to solve the problem that the existing tungsten chemical mechanical polishing liquid cannot polish tungsten, silicon oxide, and silicon nitride at the same time, and to control the rate and surface defects of tungsten, silicon oxide, and silicon nitride respectively, it can maintain a high tungsten polishing rate while maintaining a medium level. Silicon oxide speed and low silicon nitride speed, and can reduce the technical problems of silicon nitride surface defects. The present invention provides a chemical mechanical polishing solution, including: abrasive particles, catalysts, stabilizers, cross-linked macromolecule surface defects Inhibitors, oxidants, water and pH adjusters.

In some embodiments, the cross-linked macromolecule surface defect inhibitor is carbomer.

In some embodiments, the model of the carbomer is one or more of 934 (that is, carbomer 934), 940 (that is, carbomer 940), and 941 (that is, carbomer 941), and carbomer 934 The difference between carbomer 940 and carbomer 941 is the difference in viscosity.

In some embodiments, the concentration range of the 940 carbomer is 0.005% to 0.1%.

In some embodiments, the concentration range of the 940 carbomer is 0.005% to 0.05%.

In some embodiments, the abrasive particles are SiO ₂ .

In some embodiments, the concentration of the abrasive particles ranges from 0.5% to 3%.

In some embodiments, the concentration of the abrasive particles ranges from 1% to 3%.

In some embodiments, the catalyst is selected from ferric nitrate nonahydrate.

In some embodiments, the concentration of the ferric nitrate nonahydrate ranges from 0.01% to 0.1%.

In some embodiments, the concentration of the ferric nitrate nonahydrate ranges from 0.01% to 0.07%.

In some embodiments, the stabilizer is a carboxylic acid that can be complexed with iron.

In some embodiments, the carboxylic acid that can be complexed with iron is selected from one or more of phthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, citric acid, and maleic acid.

In some embodiments, the carboxylic acid that can be complexed with iron is malonic acid.

In some embodiments, the concentration of malonic acid ranges from 0.05% to 0.3%.

, The concentration of the malonic acid ranges from 0.1% to 0.27%.

In some embodiments, the oxidant is H ₂ O ₂ .

In some embodiments, the concentration of the oxidant ranges from 1 to 2%.

In some embodiments, the pH adjusting agent is HNO ₃ .

In some embodiments, the pH is 2~4. When the pH is less than 2, the chemical mechanical polishing liquid is a dangerous product, and when the pH is more than 4, it will cause the instability of the abrasive particles and the precipitation of Fe.

It should be understood that the% in the concentration in the present invention all refers to the mass percentage concentration.

Compared with the prior art, the advantages of the present invention are:

The chemical mechanical polishing liquid of the present application realizes the simultaneous polishing of tungsten, silicon oxide and silicon nitride, and at the same time, it ensures a high polishing speed of tungsten while having both a medium silicon oxide speed and a low silicon nitride speed. At the same time, the present application By adding carbomer to the chemical mechanical polishing solution, the surface defects of the silicon nitride surface after polishing are greatly reduced, the silicon nitride surface defects are suppressed, and the rapid planarization is achieved.

Hereinafter, the chemical mechanical polishing composition for polishing tungsten of the present invention will be described in detail through specific examples, so as to better understand the present invention, but the following examples do not limit the scope of the present invention.

It should be understood that the% in the concentration in the present invention all refers to the percentage by mass.

Example

Preparation method: Dissolve and mix all the components uniformly according to the formula in Table 1, make up the mass percentage with water to 100%, and adjust the pH to the desired value with a pH regulator.

Table 1. The types and corresponding concentrations of each component of each example and comparative example Example Abrasive particles Oxidant catalyst stabilizer Cross-linked macromolecular surface defect inhibitor pH regulator pH type concentration type concentration type concentration type concentration type concentration Example 1 SiO ₂ 1.0% Hydrogen peroxide 1.00% Ferric Nitrate Nonahydrate 0.01% Malonate 0.10% Carbomer 940 0.005% HNO ₃ 2 Example 2 SiO ₂ 1.0% Hydrogen peroxide 1.00% Ferric Nitrate Nonahydrate 0.01% Malonate 0.10% Carbomer 941 0.005% HNO ₃ 2 Example 3 SiO ₂ 1.0% Hydrogen peroxide 1.00% Ferric Nitrate Nonahydrate 0.01% Malonate 0.10% Carbomer 934 0.005% HNO ₃ 2 Example 4 SiO ₂ 2.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.05% Malonate 0.18% Carbomer 940 0.015% HNO ₃ 2 Example 5 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% Carbomer 940 0.015% HNO ₃ 2 Example 6 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% Carbomer 940 0.050% HNO ₃ 2 Example 7 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% Carbomer 940 0.100% HNO ₃ 2 Example 8 SiO ₂ 0.5% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.10% Malonate 0.05% Carbomer 940 0.015% HNO ₃ 2 Example 9 SiO ₂ 3.0% Hydrogen peroxide 3.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.30% Carbomer 940 0.015% HNO ₃ 2 Example 10 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% Carbomer 940 0.015% HNO ₃ 3 Example 11 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% Carbomer 940 0.015% HNO ₃ 4 Comparative example 1 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% —— —— HNO ₃ 2 Comparative example 2 SiO ₂ 2.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.05% Malonate 0.18% —— —— HNO ₃ 2 Comparative example 3 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% acrylic acid 0.015% HNO ₃ 2 Comparative example 4 SiO ₂ 1.0% Hydrogen peroxide 1.0% Ferric Nitrate Nonahydrate 0.01% Malonate 0.10% —— —— HNO ₃ 2

Effect example

The chemical mechanical polishing solutions of the various examples and comparative examples in Table 1 were used to polish tungsten, silicon oxide, and silicon nitride wafers and measure the surface defects of the silicon nitride wafers according to the following experimental conditions, and the results in Table 2 were obtained.

Polishing method: The polishing machine is a 12-inch polishing machine (Reflexion LK) from Applied Materials, with a pressure of 3.0 psi, a polishing disk and head rotating speed of 93/87 rpm, a polishing pad IC1010, a polishing fluid flow rate of 150 ml/min, and a polishing time of 1 minute.

Surface defect measurement method: Use KLA-Tencor's unpatterned wafer defect inspection system (Surfscan SP2) to measure the surface of silicon nitride, and count defects with a diameter greater than 120 nm.

Table 2. Examples and comparative examples on the polishing rate of tungsten, silicon oxide, and silicon nitride, and the inhibitory effect on silicon nitride surface defects Tungsten polishing speed (Å/min) Silicon oxide polishing speed (Å/min) Silicon nitride polishing speed (Å/min) Silicon nitride surface defects (>120 nm, 1% ammonia water cleaning) Comparative example 1 3651 587 218 976 Comparative example 2 3273 503 148 824 Comparative example 3 3608 566 235 939 Comparative example 4 2399 532 131 902 Example 1 2356 544 187 303 Example 2 2318 531 162 355 Example 3 2325 539 165 378 Example 4 3107 545 182 169 Example 5 3611 625 228 162 Example 6 3552 598 219 147 Example 7 3409 585 202 101

Examples 1-7 show that the chemical mechanical polishing solution of the present invention can simultaneously polish tungsten, silicon oxide and silicon nitride, and the polishing speed: tungsten>silicon oxide>silicon nitride, while maintaining high tungsten polishing The speed has both a medium silicon oxide speed and a low silicon nitride speed. At the same time, it has the ability to suppress the surface defects of the silicon nitride after polishing. Among them, the polishing speed of tungsten is positively correlated with the concentration of the oxidant, or the concentration of abrasive particles, or the concentration of the catalyst, or the concentration of the oxidant. Specifically, the concentration of the oxidant in Examples 1-3 in Table 2 is 1.00%, and the corresponding tungsten polishing rates are 2356, 2318, and 2325 respectively; when the concentration of the oxidant increases to 2.0% (as in Example 4-7 ), the corresponding tungsten polishing rates are 3107, 3611, 3552, and 3409 respectively. Specifically, in Table 2, the concentrations of abrasive particles in Examples 1-3 are all 1.0%, and the corresponding tungsten polishing rates are 2356, 2318, and 2325 respectively; when the concentration of abrasive particles increases to 2.0% (as in Example 4) The corresponding tungsten polishing rate is 3107; when the concentration of abrasive particles increases to 3.0% (as in Examples 5-7), the corresponding tungsten polishing rates are 3611, 3552, and 3409, respectively. Specifically, in Table 2 the concentration of the catalyst in Examples 1-3 is 0.01%, and the corresponding tungsten polishing rates are 2356, 2318, and 2325 respectively; when the concentration of the catalyst increases to 0.05% (as in Example 4), the corresponding tungsten polishing rate is The tungsten polishing rate is 3107; when the concentration of the catalyst increases to 0.07% (as in Examples 5-7), the corresponding tungsten polishing rates are 3611, 3552, and 3409, respectively. Therefore, the polishing speed of tungsten can be adjusted by adjusting the amount of oxidant, abrasive particles, and catalyst.

Through the comparison of Comparative Examples 1-2 and Examples 1-7, it is found that on the basis of the same grinding particles, catalyst, stabilizer, oxidant and pH, carbomer (such as carbomer 934, carbomer 940, carbomer姆941) significantly improved the surface defects of silicon nitride after polishing. Specifically, through Examples 1-3 and Comparative Example 4, it can be found that on the basis of the same abrasive particles, catalyst, stabilizer, oxidant and pH, carbomer (carbomer 934, carbomer 940, carbomer姆941) The surface defects of silicon nitride after polishing have been significantly improved, and the surface defects of silicon nitride have been reduced from about 900 to about 300. In the same way, the same conclusion can be drawn through Example 4 and Comparative Example 2. The same conclusion can be drawn from Examples 5-7 and Comparative Example 1 and Comparative Example 3. In addition, it can be concluded from Examples 5-7 that, on the basis of the same abrasive particles, catalyst, stabilizer, oxidant and pH, as the amount of carbomer continues to increase, the number of defects decreases accordingly. One-ninth of the time when Kaboom. At the same time, the amount of carbomer does not have much effect on the polishing speed. Specifically, when the concentration of carbomer 940 is 0.015% (embodiment 5), the corresponding silicon nitride surface defect is 162; when the concentration of carbomer 940 is 0.050% (embodiment 5), the corresponding nitrogen The surface defect of silicon nitride is 147; when the concentration of carbomer 940 is 0.100% (Example 5), the corresponding silicon nitride surface defect is 101 (about one-ninth of the silicon nitride surface defect 976 in Comparative Example 1) one).

Through the comparison between Comparative Example 3 and Example 5, it is found that the chemical mechanical polishing liquid obtained by adding the monomer acrylic acid of carbomer has no ability to correct the defects of silicon nitride after polishing. Specifically, on the basis that the abrasive particles, catalyst, stabilizer, oxidant and pH are completely the same, and the concentration of carbomer 940 in Example 5 is consistent with the concentration of acrylic acid in Comparative Example 3, the The chemical mechanical polishing solution has the ability to suppress silicon nitride surface defects, which is reduced from 976 in Comparative Example 1 to 162 compared to Comparative Example 1, while the composition in Comparative Example 3 does not have the ability to suppress silicon nitride surface defects, because The surface defects of Comparative Example 3 were similar to those of Comparative Example 1.

The specific embodiments of the present invention are described in detail above, but they are only examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions made to the present invention are also within the scope of the present invention. Therefore, all equivalent changes and modifications made without departing from the spirit and scope of the present invention should all fall within the scope of the present invention.

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Claims (20)

A chemical mechanical polishing liquid includes abrasive particles, a catalyst, a stabilizer, a cross-linked macromolecular surface defect inhibitor, an oxidizer, water and a pH regulator. The chemical mechanical polishing liquid according to claim 1, wherein the cross-linked macromolecule surface defect inhibitor is carbomer. The chemical mechanical polishing liquid according to claim 2, wherein the model number of the carbomer is one or more of 934, 940, and 941. The chemical mechanical polishing liquid according to claim 3, wherein the concentration of the carbomer model 940 ranges from 0.005% to 0.1%. The chemical mechanical polishing liquid according to claim 4, wherein the concentration range of the carbomer model 940 is 0.005% to 0.05%. The chemical mechanical polishing liquid according to claim 1, wherein the abrasive particles are SiO2. The chemical mechanical polishing liquid according to claim 1, wherein the concentration of the abrasive particles ranges from 0.5% to 3%. The chemical mechanical polishing liquid according to claim 7, wherein the concentration of the abrasive particles ranges from 1% to 3%. The chemical mechanical polishing liquid according to claim 1, wherein the catalyst is selected from ferric nitrate nonahydrate. The chemical mechanical polishing liquid according to claim 9, wherein the concentration of the ferric nitrate nonahydrate ranges from 0.01% to 0.1%. The chemical mechanical polishing liquid according to claim 10, wherein the concentration of the ferric nitrate nonahydrate ranges from 0.01% to 0.07%. The chemical mechanical polishing liquid according to claim 1, wherein the stabilizer is a carboxylic acid that can be complexed with iron. The chemical mechanical polishing liquid according to claim 12, wherein the carboxylic acid that can be complexed with iron is selected from the group consisting of phthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, citric acid, and maleic acid. One or more of the acids. The chemical mechanical polishing liquid according to claim 13, wherein the carboxylic acid that can be complexed with iron is malonic acid. The chemical mechanical polishing liquid according to claim 14, wherein the concentration of the malonic acid ranges from 0.05% to 0.3%. The chemical mechanical polishing liquid according to claim 15, wherein the concentration of the malonic acid ranges from 0.1% to 0.27%. The chemical mechanical polishing liquid according to claim 1, wherein the oxidizing agent is H ₂ O ₂ . The chemical mechanical polishing liquid according to claim 17, wherein the concentration of the oxidant ranges from 1 to 2%. The chemical mechanical polishing liquid according to claim 1, wherein the pH adjusting agent is HNO ₃ . The chemical mechanical polishing liquid according to claim 1, wherein the pH of the chemical mechanical polishing liquid is 2~4.