WO2022089624A1

WO2022089624A1 - Composite catalyst for chemical mechanical planarization and preparation method therefor, and polishing solution

Info

Publication number: WO2022089624A1
Application number: PCT/CN2021/127773
Authority: WO
Inventors: 杨勍; 邹海良; 周慧慧
Original assignee: 华为技术有限公司
Priority date: 2020-10-31
Filing date: 2021-10-30
Publication date: 2022-05-05
Also published as: CN114433159A

Abstract

Embodiments of the present application provide a composite catalyst for chemical mechanical planarization, the composite catalyst comprising a carrier, catalyst nanoparticles supported on the carrier, and a porous protective layer wrapping the carrier and the catalyst nanoparticles, wherein the carrier includes an inorganic carrier or a polymer carrier, and the porous protective layer includes a porous material. The composite catalyst has a high catalytic efficiency, and neither inherently limits the pH range of a polishing solution nor has metal ion pollution, thereby facilitating post-cleaning and reduction of the device defect rate; and the presence of the porous protective layer can avoid direct friction between the catalyst nanoparticles and the surface of a device, thereby avoiding device scratching and catalyst failure. Using the polishing solution of the composite catalyst of the embodiments of the present application for a chemical mechanical planarization process can facilitate a post-cleaning process while improving the polishing rate and reducing the generation of device defects. Further provided are a method for preparing the composite catalyst and a polishing solution using the composite catalyst.

Description

[Correction 22.01.2022 according to Rule 91] A planarizing material and its preparation method and application

This application claims the priority of the Chinese patent application filed on October 31, 2020 with the application number 202011200692.6 and the application name "Composite catalyst for chemical mechanical planarization and its preparation method and polishing liquid", which The entire contents of this application are incorporated by reference.

technical field

The embodiments of the present application relate to the technical field of chemical mechanical planarization, and in particular, to a composite catalyst for chemical mechanical planarization, a preparation method thereof, and a polishing liquid.

Background technique

Chemical Mechanical Planarization (CMP) is an indispensable process in the chip manufacturing process. It uses the synergy of chemical reaction and mechanical friction to remove the material in the protruding part of the chip processing process, so as to realize the global flatness of the chip. change. For example, in the tungsten plug/tungsten interconnect structure shown in FIG. 1 , after the tungsten metal 2 is deposited on the oxide 1 , the excess tungsten metal is removed by a CMP process. The polishing quality of the chemical mechanical planarization process directly affects the yield of the chip.

In the CMP process, the polishing liquid largely determines the polishing rate, planarization effect, selectivity ratio and defect rate, etc., which affects the polishing quality. For different materials, device designs, and process requirements, the formulation of the polishing solution is highly customized. For example, a typical tungsten polishing solution generally contains abrasive particles, catalysts, oxidants, and the like. During the CMP process of tungsten, under the action of the catalyst, the oxidant decomposes a large number of hydroxyl radicals to react with the tungsten, and oxidize the tungsten into loose oxides, which are then removed by the mechanical action of abrasives. The most critical ingredient for rate.

At present, there are two main types of catalysts: ionic catalysts and solid catalysts. However, these two types of catalysts have the following problems: For ionic catalysts, the presence of soluble metal ions (such as Fe ³⁺ ) limits the pH of the polishing solution, and the residual metal ions increase the difficulty of post-cleaning (the residual metal ions will cause device damage). The defect rate has increased significantly). The solid catalyst can eliminate the problem of metal ion contamination, but its physical friction with the surface of the device is likely to cause scratches, and nano-scale catalyst particles are also easy to remain on the device. In order to solve the problems brought by traditional ionic catalysts and solid-state catalysts, it is necessary to design a new type of catalyst for CMP polishing solution.

SUMMARY OF THE INVENTION

In view of this, the embodiments of the present application provide a composite catalyst for chemical mechanical planarization, so as to solve the problems of the existing ionic catalysts, which lead to limited pH of the polishing solution, difficult removal of metal ions, and the existence of solid catalysts. It is easy to cause scratches on the surface of the device due to physical friction.

In a first aspect, embodiments of the present application provide a composite catalyst for chemical mechanical planarization, comprising a carrier, catalyst nanoparticles supported on the carrier, and a catalyst nanoparticle that wraps the carrier and the catalyst nanoparticles. A porous protective layer, the carrier includes an inorganic carrier or a polymer carrier, and the porous protective layer includes a porous material.

The composite catalyst in the examples of the present application uses solid nanoparticles as the catalyst, and the catalyst itself does not limit the pH range of the polishing solution, which can expand the selectivity of other formulation components in the polishing solution; at the same time, there are no metal ions and free nanoparticles Particle contamination facilitates post-cleaning and reduces device defectivity. In addition, the outermost layer of the composite catalyst of the embodiments of the present application is provided with a porous protective layer, and the existence of the porous protective layer can avoid direct friction between the catalyst nanoparticles and the surface of the device, and avoid device scratches and catalyst failure. The CMP process using the polishing liquid of the composite catalyst of the embodiments of the present application can improve the polishing rate and facilitate the post-cleaning process, reduce the generation of device defects, and solve the problems of the existing ionic catalysts and solid catalysts that cause the pH of the polishing liquid to be limited, Metal ions are difficult to remove, and it is easy to cause technical problems such as scratches on the surface of the device.

In the embodiments of the present application, the porous material includes one or more of porous oxide, porous carbon, zeolite, and metal organic framework.

In the embodiment of the present application, the porous pore diameter of the porous protective layer is 2 nm-100 nm. Appropriate pore size setting can make the reactant enter into the composite catalyst smoothly and quickly, and contact with the catalyst nanoparticles 20, so as to ensure the smooth progress of the chemical reaction and improve the polishing efficiency.

In the embodiment of the present application, the thickness of the porous protective layer is 5 nm-100 nm. A suitable thickness of the protective layer can effectively prevent friction caused by the direct contact between the internal carrier and the catalyst nanoparticles and the surface of the device, and can also keep the overall particle size of the composite catalyst 100 at a small size.

In the embodiment of the present application, the specific surface area of the composite catalyst is in the range of 200m ² /g-1000m ² /g.

In the embodiment of the present application, the porous protective layer is formed by in-situ growth. Specifically, when the catalyst nanoparticles completely cover the surface of the carrier, the porous material of the porous protective layer grows in situ on the outer surface of the catalyst nanoparticles. When the catalyst nanoparticles do not completely cover the surface of the carrier, the porous material of the porous protective layer may be partially grown in situ on the surface of the carrier and partially grown on the outer surface of the catalyst nanoparticles.

In the embodiments of the present application, the inorganic carrier includes one or more of SiO ₂ , Al ₂ O ₃ , CeO ₂ , TiO ₂ , CaCO ₃ , ZrO, ZnO, Fe ₃ O ₄ , and activated carbon.

In the embodiments of the present application, the polymer carrier includes one or more of polystyrene and polymethyl methacrylate.

In the embodiment of the present application, the particle size of the carrier is in the range of 5 nm-5 μm.

In the embodiment of the present application, the carrier has a porous structure. Using a carrier with a porous structure can increase the specific surface area of the carrier, thereby increasing the loading of catalyst nanoparticles on the surface of the carrier, and at the same time, it is also conducive to the dispersion and arrangement of catalyst nanoparticles, and the catalytic effect is improved.

In the embodiment of the present application, the specific surface area of the carrier is in the range of 50 m ² /g-200 m ² /g. The carrier with higher specific surface area can improve the loading of catalyst nanoparticles.

In the embodiments of the present application, the catalyst nanoparticles may be any catalyst particles with catalytic activity that can be used in a chemical mechanical planarization process, and may specifically include metal elements, alloys, metal oxides, and metal sulfides with catalytic activity. one or more of.

In the embodiment of the present application, the catalyst nanoparticles include Fe ₃ O ₄ /Fe ₂ O ₃ , TiO ₂ , MnO ₂ /Mn ₃ O ₄ , CoO ₂ , Cu _2-x O, Au, FeSi, FeCo, Cu ₂ One or more of _-x S, where 0<x<2.

In the embodiment of the present application, the particle size of the catalyst nanoparticles is 5 nm-50 nm. Nano-sized catalysts have a high specific surface area, which can effectively improve the catalytic efficiency.

In a second aspect, the embodiments of the present application provide a method for preparing a composite catalyst for chemical mechanical planarization, including:

Disperse the carrier in a solvent to prepare a homogeneous solution; the carrier includes an inorganic carrier or a polymer carrier;

adding the catalyst nanoparticles into the homogeneous solution, stirring the catalyst nanoparticles to load the catalyst nanoparticles on the carrier, and separating the catalyst nanoparticles-loaded carrier;

A porous material is grown in-situ on the catalyst nanoparticle-loaded carrier to form a porous protective layer, and the porous protective layer wraps the carrier and the catalyst nanoparticle inside.

The preparation method provided in the second aspect of the embodiment of the present application has a simple process and is easy to realize industrialized production.

In a third aspect, an embodiment of the present application provides a polishing solution for chemical mechanical planarization, the polishing solution includes the composite catalyst for chemical mechanical planarization, abrasive particles, and an oxidizing agent described in the first aspect of the embodiment of the present application. and solvent.

In the embodiment of the present application, in the polishing liquid, the mass concentration of the composite catalyst is 50 ppm-2000 ppm.

In the embodiment of the present application, the polishing liquid further includes one or more of a pH adjuster, a stabilizer, and a corrosion inhibitor.

In the polishing solution provided in the third aspect of the embodiments of the present application, each component can be adjusted according to the needs of the CMP process, and various chemical mechanical planarization requirements can be achieved.

The embodiments of the present application further provide a method for chemical mechanical planarization of the surface of a device, using the polishing liquid for chemical mechanical planarization described in the third aspect of the embodiments of the present application. In the embodiments of the present application, the device includes a chip. It should be noted that, in the chip manufacturing process, chemical mechanical planarization processes are usually required at different stages. Therefore, the chip of the embodiment of the present application may be a chip structure formed at any stage in the manufacturing process. The chemical mechanical planarization method of the embodiment of the present application, because the composite catalyst with a specific structure of the embodiment of the present application is used, the polishing rate can be improved, and the post-cleaning process can be improved, the generation of device defects can be reduced, and the polishing quality can be obtained. Improve chip yield.

Description of drawings

Fig. 1 is the schematic diagram of adopting chemical mechanical planarization to remove tungsten;

FIG. 2 is a schematic structural diagram of a composite catalyst 100 for chemical mechanical planarization according to an embodiment of the present application;

FIG. 3 is a schematic structural diagram of a composite catalyst 100 for chemical mechanical planarization provided by another embodiment of the present application;

4 is a schematic flowchart of a method for preparing a composite catalyst for chemical mechanical planarization provided in an embodiment of the present application;

FIG. 5 is a schematic diagram of the operation of chemical-mechanical planarization of the chip.

Detailed ways

The embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application.

Referring to FIG. 2 , an embodiment of the present application provides a composite catalyst 100 for chemical mechanical planarization, which includes a carrier 10 , catalyst nanoparticles 20 supported on the carrier 10 , and a catalyst nanoparticle 20 that wraps the carrier 10 and the catalyst nanoparticles 20 . For the porous protective layer 30, the carrier 10 includes an inorganic carrier or a polymer carrier, and the porous protective layer 30 includes a porous material.

In the embodiment of the present application, the carrier 10 itself does not have a catalytic effect, and is mainly used to support the catalyst nanoparticles. At the same time, the existence of the carrier 10 is conducive to nucleation and the dispersion of the catalyst nanoparticles 20 . The carrier 10 can be selected in various ways, which can be an inorganic carrier or an organic carrier. The inorganic carrier may be one or more of SiO ₂ , Al ₂ O ₃ , CeO ₂ , TiO ₂ , CaCO ₃ , ZrO, ZnO, Fe ₃ O ₄ , and activated carbon. The polymer carrier includes one or more of polystyrene and polymethyl methacrylate. Specifically, the inorganic carrier can be inorganic microspheres, and the polymer carrier can be polymer microspheres. The specific shape of the carrier 10 is not limited, and may be a spherical shape, a spherical shape, an ellipsoid shape, etc., a solid sphere, or a sphere with a hollow structure.

In the embodiment of the present application, the particle size of the carrier 10 is in the range of 5 nm-5 μm. In some embodiments, the particle size of the carrier 10 is in the range of 10 nm to 1000 nm. In other embodiments, the particle size of the carrier 10 is in the range of 20nm-500nm. When the carrier 10 is a microsphere, the particle size is the diameter of the carrier particle.

In some embodiments of the present application, the carrier 10 has a porous structure, and the use of a carrier with a porous structure can increase the specific surface area of the carrier, thereby increasing the loading of catalyst nanoparticles on the surface of the carrier, and at the same time, it is also conducive to the dispersion and arrangement of catalyst nanoparticles, Improve catalytic effect. The porous pore size of the carrier 10 may be in the range of 2nm-50nm. Specifically, for example, it is 2 nm-30 nm and 10 nm-20 nm. A suitable pore size can effectively increase the surface area of the carrier while ensuring the structural strength of the carrier. In the embodiment of the present application, the specific surface area of the carrier may be in the range of 50m ² /g-200m ² /g. Further, the specific surface area of the carrier may be in the range of 80m ² /g-150m ² /g. Further, the specific surface area of the carrier may be in the range of 100m ² /g-120m ² /g.

In the embodiment of the present application, the catalyst nanoparticles 20 may be any catalyst nanoparticles that can have actual catalytic effect in the chemical mechanical planarization process. Specifically, the catalyst nanoparticles 20 may include one or more of metal elements, alloys, metal oxides, and metal sulfides with catalytic activity. The metal element can be a noble metal element (such as Au); the alloy can be an alloy composed of different metal elements (such as FeCo alloy), or an alloy composed of a metal element and a non-metal element (such as FeSi alloy). Specifically, in some embodiments of the present application, the catalyst nanoparticles 20 include but are not limited to Fe ₃ O ₄ , Fe ₂ O ₃ , TiO ₂ , MnO ₂ , Mn ₃ O ₄ , CoO ₂ , Cu _2-x O, Au , one or more of FeSi, FeCo, Cu _2-x S, wherein 0<x<2.

In the embodiment of the present application, the particle size of the catalyst nanoparticles 20 is 5 nm-50 nm. Nano-sized catalysts have a high specific surface area, which can effectively improve the catalytic efficiency. In some specific embodiments of the present application, the particle size of the catalyst nanoparticles 20 is 5 nm, 8 nm, 10 nm, 15 nm, 20 nm, 30 nm, 40 nm, and 50 nm. Among them, selecting catalyst nanoparticles with a particle size smaller than 10 nm can obtain a higher specific surface area and better improve the catalytic efficiency.

In the embodiment of the present application, the catalyst nanoparticles 20 may partially cover the outer surface of the carrier 10 , that is, the outer surface of the carrier 10 is partially exposed; or may completely cover the outer surface of the carrier 10 . Specifically, the catalyst nanoparticles 20 may cover an area of 1% to 100% of the surface of the carrier 10 . The catalyst nanoparticles 20 may be supported on the surface of the carrier 10 by chemical or physical means, such as being fixed on the surface of the carrier 10 by physical adsorption or chemical bonding. In order to better achieve physical or chemical loading, a specific functional group can be modified on the surface of the catalyst nanoparticles 20 to change the charge state on the surface of the carrier or make the carrier reactive, so as to achieve physical adsorption or chemical adsorption with the carrier 10 through the functional group. connect. Specifically, the functional group may be, for example, an amino group, a carboxyl group, a polyethylene glycol group, or the like.

In the embodiment of the present application, the porous protective layer 30 is wrapped around the carrier 10 and the catalyst nanoparticles 20, which can effectively prevent the carrier and the catalyst nanoparticles from directly contacting the device surface during the polishing process, reduce friction, and reduce the defect rate of the device surface; It can effectively protect the catalyst nanoparticles, reduce the shedding of the catalyst nanoparticles, prolong the service life of the catalyst, and avoid the pollution of the free catalyst nanoparticles. The porous material of the porous protective layer 30 may include one or more of porous oxides, porous carbons, zeolites, and metal organic frameworks. Among them, the porous oxide may be, for example, porous silica or porous alumina. Metal-Organic Frameworks (MOFs) are organic-inorganic hybrid materials with intramolecular pores formed by the self-assembly of organic ligands and metal ions or clusters through coordination bonds. The porous structure of the porous protective layer 30 enables the encapsulated catalyst nanoparticles 20 to effectively exert its catalytic effect during the polishing process; that is, the device surface is protected from scratches by the catalyst nanoparticles without affecting the catalytic effect of the catalyst. Moreover, the porous structure of the porous protective layer will not affect the penetration and diffusion of reactants such as oxidants, and can ensure the catalytic efficiency.

In the embodiment of the present application, the porous pore size of the porous protective layer 30 may be adjustable in the range of 2 nm-100 nm. In some embodiments, the porous pore size of the porous protective layer 30 may be in the range of 10 nm-80 nm, or may be in the range of 20 nm-60 nm. Appropriate pore size setting can make the reactant enter into the composite catalyst smoothly and quickly, and contact with the catalyst nanoparticles 20, so as to ensure the smooth progress of the chemical reaction and improve the polishing efficiency.

In the embodiment of the present application, the thickness of the porous protective layer 30 is 5 nm-100 nm. In some embodiments, the thickness of the porous protective layer 30 may be 10 nm-80 nm; in other embodiments, the thickness of the porous protective layer 30 may be 20 nm-60 nm. A suitable thickness of the protective layer can effectively prevent friction caused by the direct contact between the internal carrier and the catalyst nanoparticles and the surface of the device, and can also keep the overall particle size of the composite catalyst 100 at a small size.

In the embodiment of the present application, the porous protective layer 30 may be prepared by in-situ growth.

In some embodiments, the porous material is grown in situ on the outer surface of the carrier supporting the catalyst nanoparticles, forming a three-layered particle structure of carrier-catalyst nanoparticles-porous protective layer from the inside to the outside (as shown in FIG. 2 ). In this embodiment, when the carrier is completely covered by the catalyst nanoparticles, the porous material grows on the surface of the catalyst nanoparticles in situ, that is, the porous protective layer and the catalyst nanoparticles are in contact with each other; and when the carrier is partially covered by the catalyst nanoparticles During coating, part of the porous material grows on the surface of the catalyst nanoparticles in situ, and part of the porous material grows on the surface of the carrier, that is, the porous protective layer is in contact with the carrier and the catalyst nanoparticles. The porous protective layer is uniformly coated on the carrier supporting the catalyst nanoparticles.

In other embodiments, after the porous material layer is prepared by in-situ growth, the porous material can be partially removed to form a composite catalyst with a core-shell structure as shown in FIG. 3 . The carriers 10 are not in direct contact, but a certain gap 40 is formed. The carrier supporting the catalyst nanoparticles can movably exist in the hollow inner cavity formed by the porous protective layer 30 .

In the embodiment of the present application, the porous protective layer 30 is wrapped to form a hollow inner cavity, and the carrier supporting the catalyst nanoparticles may completely occupy the hollow inner cavity (as shown in FIG. 2 ), or may partially occupy the hollow inner cavity (such as shown in Figure 3). Specifically, the catalyst nanoparticle-loaded carrier occupies 10%-100% of the volume of the hollow lumen.

In the embodiment of the present application, the specific surface area of the composite catalyst 100 is in the range of 200 m ² /g-1000 m ² /g. The composite catalyst 100 has a relatively high specific surface area, which is conducive to the smooth progress of the catalytic reaction.

The composite catalyst in the examples of the present application uses solid nanoparticles as the catalyst, and the catalyst itself does not limit the pH range of the polishing solution, which can expand the selectivity of other formulation components in the polishing solution; at the same time, there are no metal ions and free nanoparticles Particle contamination facilitates post-cleaning and reduces device defectivity. In addition, the outermost layer of the composite catalyst in the embodiments of the present application is provided with a porous protective layer, and the presence of the porous protective layer can avoid direct friction between the catalyst nanoparticles and the surface of the device, and avoid device scratches and catalyst failure. The CMP process using the polishing liquid of the composite catalyst of the embodiment of the present application has high catalytic efficiency, which can improve the polishing rate and facilitate the post-cleaning process, reduce the generation of device defects, and solve the problem of existing ionic catalysts and solid catalysts. There are technical problems such as limited pH, difficult removal of metal ions, and easy to cause scratches on the surface of the device.

The embodiments of the present application also provide a method for preparing a composite catalyst for chemical mechanical planarization. FIG. 4 is a schematic flowchart of the preparation method, and the preparation method includes:

S01. Disperse the carrier in a solvent to prepare a homogeneous solution A; the carrier includes an inorganic carrier or a polymer carrier;

In step S01, the carrier can be a commercially available product, or can be prepared by a known method. Taking SiO ₂ as an example, electronic-grade nano-SiO ₂ particles can be purchased from chemical reagent companies, or can be purchased through the industry's mature "

method" to synthesize,

method is a method of synthesizing monodisperse silica particles. In the embodiment of the present application, the carrier (eg, SiO ₂ particles) is of electronic grade purity, and the total metal content of the carrier may be below 5 ppm, and further, the total metal content may be below 1 ppm. The lower the content of metal impurities, the better to avoid the adverse effects of metal impurities on the CMP process.

In order to enable the catalyst nanoparticles to be well loaded on the surface of the carrier, the carrier can be surface-modified according to actual needs, so that the carrier surface is provided with some specific functional groups. For example, the surface of SiO ₂ particles can be modified with a silane coupling agent. The silane coupling agent may be TEOS (tetraethoxysilane), TMOS (tetramethoxysilane), or the like.

The specific features of the carrier are as described above and will not be repeated here.

The solvent can be water or an organic solvent. The organic solvent can be alcohols, ethers, ketones, glycols, organic acids, and combinations thereof. After the carrier is added to the solvent, the carrier can be uniformly dispersed by stirring to form a homogeneous solution A.

In the homogeneous solution A, the amount of the carrier added can be limited according to the specific carrier type and the dispersion in the solvent. For example, in a possible example of the present application, the mass ratio of the carrier to the solvent is (1-5):200. Ensuring that the carrier is at an appropriate mass concentration can be beneficial to the subsequent loading of catalyst nanoparticles on the carrier surface.

S02, adding the catalyst nanoparticles into the above-mentioned homogeneous solution A, stirring the catalyst nanoparticles to be loaded on the carrier, and separating the catalyst nanoparticles-loaded carrier;

The catalyst nanoparticles can be any catalyst nanoparticles capable of having a practical catalytic effect in the chemical mechanical planarization process. Specifically, the catalyst nanoparticles may include one or more of catalytically active metal elements, alloys, metal oxides, and metal sulfides. The further selection of catalyst nanoparticles is as described above, and will not be repeated here.

In the embodiment of the present application, the catalyst nanoparticles may be supported on the surface of the carrier by chemical or physical means, such as being bound on the surface of the carrier by physical adsorption or chemical bonding. In order to better achieve physical or chemical loading, specific functional groups (such as amino groups, carboxyl groups, polyethylene glycol groups, etc.) can be modified on the surface of catalyst nanoparticles to change the charge state on the surface of the carrier or make the carrier reactive. Physical adsorption or chemical attachment to the carrier is achieved through this functional group. In a specific example of the present application, amino groups are modified on the surface of iron oxide nanoparticles.

In the embodiment of the present application, the catalyst nanoparticles can be determined according to the actual loading amount of the carrier, and the added amount of the catalyst nanoparticles can be greater than the amount that the carrier can actually support, that is, the catalyst nanoparticles are excessive. In some embodiments of the present application, the mass ratio of the catalyst nanoparticles to the carrier is (0.01-100):1.

The stirring may specifically be magnetic stirring. After the catalyst nanoparticles are fully loaded on the carrier, the catalyst nanoparticle-loaded carrier can be separated by centrifugation and dried. While realizing separation, the centrifugation process can also remove catalyst nanoparticles that are not stably supported on the carrier, thereby reducing the adverse effects of subsequent detachment of catalyst nanoparticles due to weak adhesion.

In the embodiment of the present application, the pH value of the homogeneous solution A is alkaline, and the specific pH value may be between 7-10.

S03, growing a porous material in-situ on the carrier supporting the catalyst nanoparticles to form a porous protective layer, and the porous protective layer wraps the carrier and the catalyst nanoparticles inside.

Specifically, in an embodiment of the present application, a porous protective layer is formed on a carrier supporting catalyst nanoparticles by means of liquid phase in-situ growth.

Exemplarily, the specific operation of in-situ growth of the porous SiO ₂ protective layer using the liquid-phase template method may be:

S301, dispersing the catalyst nanoparticle-loaded carrier into a solvent, and stirring to form a homogeneous solution B;

In this step, the mass ratio of the carrier supporting the catalyst nanoparticles to the solvent may be (1-5):200. The stirring may be magnetic stirring.

S302, adding a surfactant to the homogeneous solution B, simultaneously adding an appropriate amount of alcohols to improve the solubility of the surfactant, and stirring to form a homogeneous solution C;

The surfactant in this step acts as a templating agent, and can specifically be cetyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium bromide (DTAB), MTAB, STAB, P123, P127 one or more of. The alcohols can be, for example, one or more of methanol, ethanol, n-propanol, isopropanol, and ethylene glycol.

S303, after the pH value of the homogeneous solution C is adjusted to alkaline by an acid or alkali solution, a silicon source is added, and then placed in a hydrothermal kettle for hot water aging, and finally the surfactant is removed, and dried to obtain a chemical mechanical Planarized composite catalyst.

The acid or alkali solution in this step is generally selected from inorganic bases and acids, such as sodium hydroxide, potassium hydroxide, ammonia water, phosphoric acid, hydrochloric acid, nitric acid or sulfuric acid. The pH value of homogeneous solution C can be adjusted to between 7-9 by acid or alkali solution.

The silicon source in this step mainly includes an organic silicon source and an inorganic silicon source, specifically methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, butyl orthosilicate, sodium silicate, potassium silicate, Silica sol, etc.

In the embodiment of the present application, the mass ratio of the silicon source to the surfactant may be in the range of 1:(0.1-0.4).

In the embodiment of the present application, the mass ratio of the silicon source to the solvent may be in the range of 1:(50-600).

In the embodiment of the present application, the aging temperature may be between 50-150° C.; and the aging time may be between 2-72 hours.

In the embodiments of the present application, the removal method of the surfactant may be cleaning and removal using an organic solvent (eg, ethanol), or may be removal by baking. The calcination temperature can be 500-650°C, and the calcination time can be 5-24 hours.

In the above preparation method of the present application, the specific manner of the stirring operation involved in each step may be magnetic stirring.

Embodiments of the present application further provide a polishing liquid for chemical mechanical planarization, the polishing liquid comprising the composite catalyst for chemical mechanical planarization, abrasive particles, oxidizing agents, and solvents described above in the embodiments of the present application. In the polishing liquid, the content of the composite catalyst can be determined according to the catalytic effect of the catalyst, the material of the device to be subjected to chemical mechanical planarization, the structure of the device, and the like. In some embodiments of the present application, the polishing liquid may be used to remove metals (eg, tungsten). Specifically, for example, in a tungsten plug/tungsten interconnect structure of an integrated circuit, the excess tungsten is removed after the tungsten metal is deposited. In the embodiment of the present application, in the polishing liquid, the mass content of the composite catalyst may be 50ppm-2000ppm (ie, equivalent to 0.05%-0.2% by mass). Specifically, in some embodiments of the present application, the mass content of the composite catalyst in the polishing liquid is 50 ppm-200 ppm. In other embodiments of the present application, the mass content of the composite catalyst in the polishing liquid is 150 ppm-500 ppm. In other embodiments of the present application, the mass content of the composite catalyst in the polishing liquid is 600ppm-1000ppm and 1200ppm-1500ppm.

The abrasive particles may be one or more of silica, alumina, titania, cerium oxide, and zirconia, or may be the above-mentioned particles that have undergone surface modification. The mass content of abrasive particles in the polishing liquid may be, but not limited to, 1%-10%. The abrasive particles are high-purity particles, and the total metal content in the abrasive particles can be less than 100 ppm, further less than 5 ppm, and further less than 1 ppm. Influence.

In the embodiments of the present application, the oxidizing agent may be one or more of hydrogen peroxide, carbamide peroxide, peroxyformic acid, peracetic acid, and peroxypropionic acid. The mass content of the oxidant in the polishing liquid can be, but not limited to, 1%-20%.

In the embodiments of the present application, the polishing liquid may further include one or more of pH adjusters, stabilizers, and corrosion inhibitors. Of course, other additives can also be added according to actual needs. The content of each component can be adjusted according to the actual needs of the CMP process. The pH adjusting agent may be a known acidic pH adjusting agent or an alkaline pH adjusting agent. Stabilizers may be, but are not limited to, malonic acid, adipic acid, phthalic acid, citric acid, malonic acid, oxalic acid, phthalic acid, phosphoric acid, nitriles, and the like. The mass content of the stabilizer can be, but not limited to, 0.01%-5%. Corrosion inhibitors can be amine functional group-containing molecules such as glycine, lysine, arginine, alanine, and imidazole.

In the embodiments of the present application, the polishing liquid can be adjusted to be acidic or alkaline according to the appropriate pH requirements of each component and the needs of the polishing process.

The embodiments of the present application further provide a method for chemical mechanical planarization of the surface of a device, using the polishing liquid for chemical mechanical planarization described in the embodiments of the present application. Specifically, it can be a chemical mechanical planarization method of the surface of the chip. At present, multiple CMP processes are usually used in the manufacturing process of chips. Taking the 28nm process node as an example, the number of CMP processes is between 10 and 15 times, while at the 7nm or more advanced process node, the number of CMP processes is at least 25 times. Therefore, the chip may be a chip structure in any process state that requires chemical mechanical planarization in the chip manufacturing process, that is, a chip structure formed at any stage in the chip manufacturing process that requires CMP processing. It is the tungsten material that usually needs to be removed by chemical mechanical planarization. For example, in the tungsten plug/tungsten interconnect structure shown in FIG. 1 , after the tungsten metal 2 is deposited on the oxide 1 , the excess tungsten metal is removed by a CMP process.

Polishing fluids, polishing pads, and conditioning disks are typically used in chemical mechanical planarization processes. As shown in FIG. 5 , during the CMP process, the polishing pad 102 is flat on the polishing table 101 , the chip 103 is hung upside down on the grinding head 104 , and then pressed on the polishing pad 102 with a certain pressure. During the CMP process, the grinding head 104 starts to rotate with the chip 103, and the polishing table 101 also rotates at a certain speed. At the same time, the polishing liquid 105 is added to the polishing pad 102 at a certain rate and spreads out with centrifugal force. The chip 103 realizes the removal of specific materials on the chip surface under the dual action of chemical and mechanical. In addition, the dressing disc 106 also rotates at a certain speed to reconstruct the uneven surface of the polishing pad 102 by cutting the outermost surface of the polishing pad 102, which is beneficial to maintain the polishing rate. After the CMP process is completed, the residual abrasives and organics on the chip surface are removed by a post-cleaning process.

The embodiments of the present application will be further described below in terms of multiple embodiments.

Example 1

A preparation method of a composite catalyst for chemical mechanical planarization, comprising the following steps.

(1) Disperse electronic-grade colloidal silica microspheres evenly in ultrapure water, prepare 100 mL of an aqueous solution with a mass concentration of 3%, and add ammonia water to adjust the pH of the aqueous solution to alkaline (pH=8.5). The average size of the colloidal silica is 150 nm.

(2) Under the condition of pH=8.5, 100 mL of an aqueous solution containing 1 wt % of amino-modified Fe ₃ O ₄ nanoparticles was added dropwise to the aqueous solution obtained in step (1) to prepare an aqueous solution containing 1.5 wt % of colloidal silica microspheres. The aqueous solution was stirred for 30 minutes, so that the Fe ₃ O ₄ nanoparticles could be fully adsorbed on the surface of the colloidal silica microspheres. Then, the colloidal silica microspheres loaded with Fe ₃ O ₄ nanoparticles were separated by centrifugation at a speed of 2000 r/min for 5 min, and then washed with deionized water. After centrifugal washing 3 times or more, drying is performed to obtain colloidal silica microspheres loaded with Fe ₃ O ₄ nanoparticles.

(3) 1 g of Fe ₃ O ₄ nanoparticles-loaded colloidal silica microspheres obtained in step (2) was added to 200 mL of deionized water, and a homogeneous solution B was formed by magnetic stirring. To the homogeneous solution B, 1 g of the surfactant cetyltrimethylammonium bromide (CTAB) and ethanol for promoting the dissolution of the surfactant CTBA were added, and the homogeneous solution C was formed by magnetic stirring.

(4) Ammonia water was added to the homogeneous solution C to adjust the pH of the solution to 8.5, and then a silicon source ethyl orthosilicate was added to obtain a mixed solution. The mass ratio among silicon source, surfactant CTBA and water is 1:0.2:200. The above-mentioned mixed solution was added to the hydrothermal kettle for hot water ageing, and the ageing temperature was 98° C. and the time was 5 hours.

(5) filter, wash, dry (drying temperature is 120 ℃), roasting after pouring out the mixed liquid after aging; roasting temperature is 600 ℃, time is 8 hours, obtains for chemical mechanical flattening Composite catalyst microspheres.

Example 2

A polishing liquid for chemical mechanical planarization, comprising silica abrasive particles (2.5% by mass), the composite catalyst prepared in Example 1 (0.04% by mass), and a hydrogen peroxide (mass content of 0.04%) 2%), the stabilizer malonic acid (mass content is 0.05%), and the solvent is water.

Example 3

A polishing liquid for chemical mechanical planarization, comprising silicon dioxide abrasive particles (mass content of 5%), the composite catalyst prepared in Example 1 (mass content of 0.04%), and hydrogen peroxide (mass content of 0.04%) 2%), the stabilizer malonic acid (mass content is 0.05%), and the solvent is water.

In order to test the polishing effect of the polishing liquids of the embodiments of the present application in the chemical mechanical planarization process, the present application sets the polishing liquids of Comparative Examples 1-4, and the composition and formula of the polishing liquids of Comparative Examples 1-4 are shown in Table 1.

Table 1 The composition of the polishing liquid of the embodiment of the present application and the comparative example

抛光液polishing liquid	磨料及质量含量Abrasive and mass content	催化剂及质量含量Catalyst and mass content	氧化剂及质量含量Oxidant and mass content	稳定剂及质量含量Stabilizer and mass content
实施例2Example 2	SiO ₂：2.5％ SiO ₂ : 2.5%	复合催化剂：0.04％Composite catalyst: 0.04%	过氧化氢：2％Hydrogen peroxide: 2%	丙二酸：0.05％Malonic acid: 0.05%
实施例3Example 3	SiO ₂：5％ SiO ₂ : 5%	复合催化剂：0.04％Composite catalyst: 0.04%	过氧化氢：2％Hydrogen peroxide: 2%	丙二酸：0.05％Malonic acid: 0.05%
对比例1Comparative Example 1	SiO ₂：2.5％ SiO ₂ : 2.5%	无none	过氧化氢：2％Hydrogen peroxide: 2%	丙二酸：0.05％Malonic acid: 0.05%
对比例2Comparative Example 2	SiO ₂：2.5％ SiO ₂ : 2.5%	无none	过氧化氢：4％Hydrogen peroxide: 4%	丙二酸：0.05％Malonic acid: 0.05%
对比例3Comparative Example 3	SiO ₂：5％ SiO ₂ : 5%	无none	过氧化氢：2％Hydrogen peroxide: 2%	丙二酸：0.05％Malonic acid: 0.05%
对比例4Comparative Example 4	SiO ₂：2.5％ SiO ₂ : 2.5%	硝酸铁：0.04％Ferric nitrate: 0.04%	过氧化氢：4％Hydrogen peroxide: 4%	丙二酸：0.05％Malonic acid: 0.05%

In order to verify the effect of the composite catalyst microspheres of the examples of the present application in CMP, the removal rate of tungsten was tested under the following chemical mechanical planarization conditions. Testing machine: Huahai Qingke Universal-300D; grinding pressure: 3psi, grinding table speed: 80RPM; grinding head speed: 150RPM; polishing fluid flow rate: 100mL/min; polishing sample: 12-inch tungsten silicon wafer.

In the CMP process of the above-mentioned conditions, the effect of the tungsten removal rate is as shown in Table 2:

Table 2 Tungsten removal rate effect

	钨去除速率(RR)Tungsten Removal Rate (RR)
实施例2Example 2	快quick
对比例1Comparative Example 1	慢slow
对比例2Comparative Example 2	慢slow
对比例3Comparative Example 3	慢slow

From the results in Table 2, it can be known that the removal rate of tungsten is very slow in the case of only abrasives and oxidants in the polishing liquids of Comparative Examples 1-3. Neither increasing the abrasive solids nor the oxidant content could increase the tungsten removal rate. However, in the polishing liquid of Example 2 of the present application, by adding a composite catalyst, the removal rate of tungsten is greatly improved, and the removal rate is relatively fast.

In order to verify that the composite catalyst microspheres are free from metal ion contamination, the polishing liquids of Example 3, Comparative Example 1, and Comparative Example 4 were subjected to chemical mechanical planarization under the above conditions, and then ICP-MS was used to detect the residual iron ions on the wafer surface. , the results are shown in Table 3.

Table 3 Tungsten removal rate and residual effect of metal ions

	钨去除速率(RR)Tungsten Removal Rate (RR)	金属离子残留metal ion residue
实施例3Example 3	快quick	无none
对比例1Comparative Example 1	慢slow	无none
对比例4Comparative Example 4	快quick	高，ppm级别High, ppm level

From the results in Table 3, it can be seen that the removal rate of tungsten is greatly improved in the presence of the catalyst. Comparative Example 4 The ionic catalyst (iron nitrate) and the composite catalyst microspheres of Example 3 of the present application can achieve the same effect, but the ionic catalyst will cause iron ions to remain on the surface of the silicon wafer, while the composite catalyst microspheres will not cause Metal ions remain. Even squeezing or heating during CMP does not cause cracking or ionization of the catalyst.

Claims

[Correction 22.01.2022 under Rule 91]
A flattening material, characterized in that it comprises a carrier, catalyst nanoparticles supported on the carrier, and a porous protective layer that wraps the carrier and the catalyst nanoparticles, and the carrier comprises an inorganic carrier or a polymer carrier, the porous protective layer includes a porous material.
The planarization material of claim 1, wherein the porous material comprises one or more of porous oxides, porous carbons, zeolites, and metal organic frameworks.
The planarizing material according to claim 1 or 2, wherein the porous pore diameter of the porous protective layer is 2 nm-100 nm.
The planarizing material according to any one of claims 1-3, wherein the thickness of the porous protective layer is 5 nm-100 nm.
The planarizing material according to any one of claims 1-4, wherein the specific surface area of the planarizing material is in the range of 200 m 2 /g-1000 m 2 /g.
The planarization material according to any one of claims 1-5, wherein the porous protective layer is formed by in-situ growth.
The planarizing material according to any one of claims 1-6, wherein the inorganic carrier comprises SiO 2 , Al 2 O 3 , CeO 2 , TiO 2 , CaCO 3 , ZrO, ZnO, Fe 3 O 4. One or more of activated carbons.
The planarizing material according to any one of claims 1-7, wherein the polymer carrier comprises one or more of polystyrene and polymethyl methacrylate.
The planarizing material according to any one of claims 1-8, wherein the particle size of the carrier is in the range of 5 nm-5 μm.
The planarizing material according to any one of claims 1-9, wherein the carrier has a porous structure.
The planarizing material according to any one of claims 1-10, wherein the carrier has a specific surface area in the range of 50m 2 /g-200m 2 /g.
The planarizing material according to any one of claims 1 to 11, wherein the catalyst nanoparticles comprise one or more of a metal element, an alloy, a metal oxide, and a metal sulfide with catalytic activity.
The planarizing material according to any one of claims 1-12, wherein the catalyst nanoparticles comprise Fe 3 O 4 , Fe 2 O 3 , TiO 2 , MnO 2 , Mn 3 O 4 , CoO 2 , One or more of Cu 2-x O, Au, FeSi, FeCo, and Cu 2-x S, wherein 0<x<2.
The planarizing material according to any one of claims 1-13, wherein the catalyst nanoparticles have a particle size of 5 nm to 50 nm.
A method for preparing a flattening material, comprising:

Disperse the carrier in a solvent to prepare a homogeneous solution; the carrier includes an inorganic carrier or a polymer carrier;

adding the catalyst nanoparticles into the homogeneous solution, stirring the catalyst nanoparticles to load the catalyst nanoparticles on the carrier, and separating the catalyst nanoparticles-loaded carrier;

A porous material is grown in-situ on the catalyst nanoparticle-loaded carrier to form a porous protective layer, and the porous protective layer wraps the carrier and the catalyst nanoparticle inside.
A polishing liquid, characterized in that, the polishing liquid comprises the flattening material according to any one of claims 1-14, abrasive particles, an oxidizing agent and a solvent.
The polishing liquid according to claim 16, wherein, in the polishing liquid, the mass concentration of the planarizing material is 50 ppm-2000 ppm.
The polishing liquid according to claim 16 or 17, characterized in that, the polishing liquid further comprises one or more of a pH adjuster, a stabilizer, and a corrosion inhibitor.
A method for planarizing the surface of a device, characterized in that the polishing liquid according to any one of claims 16-18 is used.
20. The planarization method of claim 19, wherein the device comprises a chip.