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US-12624252-B2 - Aqueous dispersion comprising inorganic particles

US12624252B2US 12624252 B2US12624252 B2US 12624252B2US-12624252-B2

Abstract

Inorganic particles comprised in an aqueous dispersion according to the present invention consist of agglomerates of crystalline and amorphous microparticles, and exhibit spherical and smooth surfaces. The spherical appearance, low crystallinity, and narrow particle size distribution of the inorganic particles are further advantageous in reducing scratch defects in a CMP process. In addition, since the microparticles on the inorganic particle surfaces provide more active sites and thus the removal rate is high, the inorganic particles may be advantageous as next-generation CMP polishing materials. In addition, the aqueous dispersion according to the present invention further comprises an amino acid, and the amino acid may be adsorbed on a surface of a silicon oxide wafer to strengthen electrostatic attraction between the silicon oxide wafer and the inorganic particles, resulting in an effect of further improving the removal rate.

Inventors

  • Taesung Kim
  • Donggeon KWAK
  • Junho Yun
  • Jae-Do Nam
  • Na Yeon KIM

Assignees

  • BEAD ORIGIN INC.

Dates

Publication Date
20260512
Application Date
20220512
Priority Date
20210512

Claims (17)

  1. 1 . An aqueous dispersion comprising inorganic particles formed by agglomeration of a plurality of elementary particles, wherein the elementary particle has a mixed phase of a crystalline phase and an amorphous phase and has a crystallinity of 90% or less, wherein the elementary particle has a particle diameter of 1 to 50 nm.
  2. 2 . The aqueous dispersion of claim 1 , further comprising an amino acid.
  3. 3 . The aqueous dispersion of claim 2 , wherein, based on a total weight of the aqueous dispersion, a content of the amino acid is 0.01 to 5% by weight, and a content of the inorganic particles is 0.01 to 5% by weight.
  4. 4 . The aqueous dispersion of claim 2 , wherein a weight ratio of the inorganic particles and the amino acid is 100:50 to 200.
  5. 5 . The aqueous dispersion of claim 2 , wherein the amino acid is one or more selected from the group consisting of tyrosine, phenylalanine, and tryptophan.
  6. 6 . The aqueous dispersion of claim 1 , wherein the inorganic particles have a density of 3.0 to 5.0 g/ml, an average particle diameter of 30 to 1000 nm, and a standard deviation of the particle diameter of 20 or less.
  7. 7 . The aqueous dispersion of claim 1 , wherein the inorganic particles have an isoelectric point of pH 5 to 7, and pH of the aqueous dispersion is 3 to 7.
  8. 8 . The aqueous dispersion of claim 1 , wherein the inorganic particles have a surface charge of +30 to +50 mV or −30 to −50 mV of zeta potential in an aqueous dispersion state of pH 4.
  9. 9 . The aqueous dispersion of claim 1 , wherein the inorganic particles are formed of oxides of one or more elements selected from the group consisting of Ga, Sn, As, Sb, Ce, Si, Al, Co, Fe, Li, Mn, Ba, Ti, Sr, V, Zn, La, Hf, Ni, and Zr.
  10. 10 . The aqueous dispersion of claim 1 , wherein the inorganic particles are CeO 2 particles, and a Ce 3+ /Ce 4+ ion ratio is 5 to 60.
  11. 11 . The aqueous dispersion of claim 1 , wherein the aqueous dispersion is a slurry for CMP.
  12. 12 . The aqueous dispersion of claim 1 , wherein the inorganic particles are prepared by a method comprising: (a) dissolving a self-assembling surfactant in water or a mixed solvent of water and a solvent compatible with water; (b) preparing an inorganic precursor solution by dissolving or dispersing an inorganic precursor in the solvent before, after, or simultaneously with step (a); and (c) forming elementary particles having a mixed phase of a crystalline phase and an amorphous phase in a shell formed by the surfactant through a self-assembly reaction of the inorganic precursor and the surfactant, and forming inorganic particles by aggregation of a plurality of the elementary particles.
  13. 13 . The aqueous dispersion of claim 12 , wherein the inorganic particles contained in the aqueous dispersion are inorganic particles of which surface charge is controlled by further comprising treating the inorganic particles obtained in step (c) with an acid and a base.
  14. 14 . The aqueous dispersion of claim 12 , wherein the self-assembling surfactant is one or more selected from the group consisting of cationic surfactants, anionic surfactants, and amphoteric surfactants having a charge capable of binding to the inorganic precursor, and has a functional group capable of condensation reaction or crosslinking reaction.
  15. 15 . The aqueous dispersion of claim 12 , wherein the functional group capable of condensation reaction or crosslinking reaction is one or more selected from the group consisting of an amide group, a nitro group, an aldehyde group, and a carbonyl group.
  16. 16 . The aqueous dispersion of claim 12 , wherein the self-assembling surfactant has a structure of the following Formula 1: wherein, in Formula 1, R 1 and R 3 are independently hydrogen atoms, C 1 -C 10 alkyl groups, or alkoxy groups, R 2 is a substituent of Formula 2 below, and n is a number of 2 or more: wherein, in Formula 2, R 4 and R 5 are independently hydrogen atoms, C 1 -C 10 alkyl groups, or alkoxy groups, R 6 is a C 1 -C 10 alkylene group or a single covalent bond, and * represents a connection site.
  17. 17 . An inorganic particle formed by agglomeration of a plurality of elementary particles wherein the elementary particle has a mixed phase of a crystalline phase and an amorphous phase, which satisfies one or more of (i) to (v) below: (i) the elementary particles have a crystallinity of 90% or less; (ii) an aspect ratio (minor axis/major axis) of the inorganic particle is 0.8 or more; (iii) a particle diameter of the elementary particle is 20 nm or less; (iv) a standard deviation of a particle diameter of the inorganic particle is 20 nm or less; (v) the inorganic particle is CeO 2 particle, and a Ce 3+ /Ce 4+ ion ratio is 40 or more.

Description

CROSS REFERENCE TO RELATED APPLICATIONS The present application is a National Stage filing of PCT Application No. PCT/KR2022/006798 filed May 12, 2022, entitled “Aqueous Dispersion Comprising Inorganic Particles”, which claims the benefit of priority based on Korean Patent Application No. 10-2021-0061195 filed on May 12, 2021. TECHNICAL FIELD The present disclosure relates to an aqueous dispersion of ceria-based particles suitable as a polishing slurry used in semiconductor device manufacturing, and the like, and more particularly, to an aqueous dispersion of ceria-based fine particles suitable for flattening a polished film formed on a substrate by chemical mechanical polishing (CMP). BACKGROUND ART High performance is being realized by increasing the density and miniaturization of semiconductor devices such as semiconductor substrates and wiring boards. In this semiconductor manufacturing process, so-called chemical mechanical polishing (CMP) is applied, and specifically, it is an essential technology for shallow trench element separation, planarization of interlayer insulating films, and formation of contact plugs and Cu damascene wiring. In general, polishing slurry for CMP includes polishing particles and chemical components, and the chemical components play a role in promoting polishing by oxidizing or corroding a target film. On the other hand, the polishing particles have the role of polishing by a mechanical action, and colloidal silica, fumed silica, and ceria (CeO2) particles are used as polishing particles. In particular, the ceria particles are applied to polishing in a process for shallow trench device separation because they exhibit a particularly high polishing speed for silicon oxide films. In the process for shallow trench device separation, polishing of a silicon nitride film is performed as well as polishing of the silicon oxide film. In order to facilitate device separation, it is desirable for the silicon oxide film to have a high polishing speed and the silicon nitride film to have a low polishing speed, so the polishing speed ratio (selectivity ratio) is also important. In addition, inorganic particles are used as raw materials or final products in various fields, and are especially utilized in a wide range of fields such as chemical catalysts, biotechnology, semiconductor processing, and tempered glass processing. A process for synthesizing these inorganic particles is very diverse, and synthesis methods are divided into a method of assembling atoms (bottom up) and a method of reducing the size of a large lump (top down) depending on preparation approaches, and are divided into physical, mechanical, and chemical methods depending on synthesis principles. Among chemical methods, the liquid phase reaction method, which uses a chemical reaction in a liquid phase, is the most widely used method for synthesizing ceramic raw material powder. As types of powder preparation processes using liquid chemical reactions, a sol-gel method, pyrolysis method, polymerized complex method, precipitation method, hydrothermal method, etc. are known. In general, during the synthesis of inorganic particles, the particles grow according to the unique assembly characteristics of the atoms, and the final shape of the inorganic particle is determined accordingly. In other words, since the shape of an inorganic particle is an inherent property of the inorganic particle, it is very difficult to prepare inorganic particles of the same composition into different shapes. For example, a ceria (CeO2) crystal has the shape of a fluorite particle with an angled hexagonal structure. When ceria particles are used as polishing particles in the slurry used in a CMP process during the semiconductor manufacturing process, scratch defects occur due to the angled structure of the ceria particles. Therefore, to solve this problem, methods for preparing ceria particles in spherical shapes are being studied. However, it is very difficult to synthesize ceria particles that are uniform in size and well dispersed while changing the shape of the angled fluorite structure ceria into a spherical shape. Additionally, as the shape of the inorganic particle changes, the specific surface area of the particle tends to vary, and the degree of chemical reaction on the particle surface may also vary accordingly. For example, when using inorganic particles as a catalyst, the specific surface area of the particle is directly related to the catalytic active site, and particles with a larger specific surface area compared to the same volume have superior reactivity. Another issue with inorganic particles is dispersion stability. Nano-sized inorganic particles (hereinafter, also referred to as ‘nanoparticles’) are generally thermodynamically unstable in aqueous solutions and have difficulty of not dispersing stably due to their high specific surface area. Therefore, there is a problem in that the particles may agglomerate during a storage process,